Clinical Focus

  • Plastic Surgery, Pediatric
  • Plastic Surgery
  • Cleft lip and palate surgery
  • Facial surgery
  • Plastic and Reconstructive Surgery
  • facial fracture surgery
  • Body contouring surgery
  • abdominal wall surgery
  • ventral hernia surgery
  • incisional hernia surgery

Academic Appointments

Administrative Appointments

  • Vice Chair, Professional Development, Department of Surgery (2023 - Present)
  • Craniofacial Fellowship Program Director, Division of Plastic Surgery (2006 - Present)
  • Service Chief, Plastic Surgery, Lucile Packard Children's Hospital (2006 - Present)

Honors & Awards

  • Leslie Hovey Teaching Award, Stanford Plastic Surgery (2005)

Professional Education

  • Fellowship: Stanford University Dept of Plastic Surgery (1998) CA
  • Residency: UCLA Dept of Plastic Surgery (1997) CA
  • Residency: UCSF General Surgery Residency (1995) CA
  • Internship: UCSF General Surgery Residency (1988) CA
  • Board Certification: American Board of Plastic Surgery, Plastic Surgery (2000)
  • Medical Education: University of Michigan School of Medicine (1987) MI
  • -, Stanford University, Craniofacial Surgery (1998)
  • -, UCLA, Plastic Surgery (1997)
  • -, UCSF, Surgery (1995)
  • MD, University of Michigan, Medicine (1987)
  • BS, UCLA, Biology (1983)

Current Research and Scholarly Interests

Dr. Lorenz graduated from the University of Michigan School of Medicine. He then completed the General Surgery Residency Program at UCSF. This program included five clinical years in surgery and three years in a research fellowship in the UCSF Fetal Treatment Center with Drs. Michael Harrison and N. Scott Adzick. The research fellowship emphasized both development of novel fetal surgical techniques and understanding the biology of scarless fetal wound healing. Next, he completed the residency program in Plastic and Reconstructive Surgery at UCLA, with an emphasis on reconstructive, cosmetic, and microsurgery. Lastly, he completed the Craniofacial Surgery Fellowship at the Lucile Packard Children’s Hospital and the Stanford University Hospital.
Dr. Lorenz then joined the full-time academic faculty at UCLA as Assistant Professor in the Department of Surgery, Division of Plastic and Reconstructive Surgery. He initiated and developed a research program that investigated the molecular regulation of scarless skin wound healing. His research also focused on the biology of fat-derived stem cells and their use for tissue engineering. He was the first UCLA Plastic Surgery faculty member to be awarded a research grant from the NIH, which he received in the field of scarless wound healing. He was Director of the Gonda Wound Treatment Center, which treated patients with refractory wounds. He was promoted to Associate Professor shortly before leaving UCLA in 2001.
Dr. Lorenz is a Professor in the Division of Plastic and Reconstructive Surgery. His clinical interests are in craniofacial surgery, pediatric plastic surgery, reconstructive surgery, and cosmetic surgery. He is certified by the American Board of Surgery and by the American Board of Plastic Surgery. He is a member of the California Society of Plastic Surgeons, the American Society of Plastic Surgeons, and the Plastic Surgery Research Council.
Dr. Lorenz directs the Scarless Skin Repair Laboratory in the Hagey Laboratory for Pediatric Regenerative Medicine. His group is studying mechanisms underlying scarless skin healing, including the interactions of fetal and adult keratinocytes and fibroblasts in the TGF-ß system. His group is also investigating the function of progenitor cells during repair, and the translational use of fat-derived stem cells in chronic wound therapy and tissue engineering.

Clinical Trials

  • Gene Transfer for Recessive Dystrophic Epidermolysis Bullosa Not Recruiting

    This trial will create a skin graft, which the investigators call "LEAES," using the patient's own skin cells that have been genetically engineered in the lab to express a missing protein called type VII collagen. The corrected cells will be transplanted back to the patient.

    Stanford is currently not accepting patients for this trial. For more information, please contact Yana Dutt-Singkh, 650-721-7166.

    View full details

2023-24 Courses

Stanford Advisees

All Publications

  • Nonsurgical Orthodontic Airway Plate Treatment for Newborns With Robin Sequence. The Cleft palate-craniofacial journal : official publication of the American Cleft Palate-Craniofacial Association Choo, H., Khosla, R. K., Meister, K. D., Wan, D. C., Lin, H. C., Feczko, R., Bruckman, K., Hopkins, E., Truong, M. T., Lorenz, H. P. 2021: 10556656211007689


    Despite promising outcomes for >50 years, nonsurgical orthodontic airway plates (OAP) are only infrequently offered for babies with Robin sequence in a few parts of the world. This article demonstrates possibility of providing functional improvement using an OAP to help these babies overcome their functional and structural difficulties on their own. Two consecutively treated cases are presented exemplifying that OAP treatment that had originated from Europe is reproducible and effective in an institution in the United States.

    View details for DOI 10.1177/10556656211007689

    View details for PubMedID 33845627

  • Adult Cranioplasty and Perioperative Patient Safety: Does Plastic Surgery Facility Volume Matter? The Journal of craniofacial surgery Rochlin, D. H., Sheckter, C. C., Khosla, R. K., Lorenz, H. P. 2020


    Cranioplasty lies at the intersection of neurosurgery and plastic surgery, though little is known about the impact of plastic surgery involvement. The authors hypothesized that adult cranioplasty patients at higher volume plastic surgery facilities would have improved inpatient outcomes. Adult cranioplasty encounters were extracted from the National Inpatient Sample from 2012 to 2014 based on International Classification of Diseases, Ninth Revision (ICD-9) codes. Regression models included the following variables: age, gender, race/ethnicity, Elixhauser Comorbidity Index, payer, hospital size, region, and urban/teaching status. Outcomes included odds of receiving a flap, perioperative patient safety indicators, and mortality. The weighted sample included 49,305 encounters with diagnoses of neoplasm (31.2%), trauma (56.4%), infection (5.2%), a combination of these diagnoses (3.9%), or other diagnoses (3.2%). There were 1375 inpatient mortalities, of which 10 (0.7%) underwent a flap procedure. On multivariable regression, higher volume plastic surgery facilities and all diagnoses except uncertain neoplasm were associated with an increased likelihood of a flap procedure during the admission for cranioplasty, using benign neoplasm as a reference (P < 0.001). Plastic surgery facility volume was not significantly associated with likelihood of a patient safety indicator event. The highest volume plastic surgery quartile was associated with lower likelihood of inpatient mortality (P = 0.008). These findings support plastic surgery involvement in adult cranioplasty and suggest that these patients are best served at high volume plastic surgery facilities.

    View details for DOI 10.1097/SCS.0000000000007177

    View details for PubMedID 33055559

  • Virtual Surgical Planning Decreases Operative Time for Isolated Single Suture and Multi-suture Craniosynostosis Repair PLASTIC AND RECONSTRUCTIVE SURGERY-GLOBAL OPEN Andrew, T. W., Baylan, J., Mittermiller, P. A., Cheng, H., Johns, D. N., Edwards, M. B., Cheshier, S. H., Grant, G. A., Lorenz, H. 2018; 6 (12): e2038


    Cranial vault reconstruction is a complex procedure due to the need for precise 3-dimensional outcomes. Traditionally, the process involves manual bending of calvarial bone and plates. With the advent of virtual surgical planning (VSP), this procedure can be streamlined. Despite the advantages documented in the literature, there have been no case-control studies comparing VSP to traditional open cranial vault reconstruction.Data were retrospectively collected on patients who underwent craniosynostosis repair during a 7-year period. Information was collected on patient demographics, intraoperative and postoperative factors, and intraoperative surgical time. High-resolution computed tomography scans were used for preoperative planning with engineers when designing osteotomies, bone flaps, and final positioning guides.A total of 66 patients underwent open craniosynostosis reconstruction between 2010 and 2017. There were 35 control (non-VSP) and 28 VSP cases. No difference in age, gender ratios, or number of prior operations was found. Blood loss was similar between the 2 groups. The VSP group had more screws and an increased length of postoperative hospital stay. The length of the operation was shorter in the VSP group for single suture and for multiple suture operations. Operative time decreased as the attending surgeon increased familiarity with the technique.VSP is a valuable tool for craniosynostosis repair. We found VSP decreases surgical time and allows for improved preoperative planning. Although there have been studies on VSP, this is the first large case-control study to be performed on its use in cranial vault remodeling.

    View details for PubMedID 30656118

  • Endoscopic Excision of Benign Facial Masses in Children: A Review of Outcomes. Journal of laparoendoscopic & advanced surgical techniques. Part A Foster, D. n., Sinclair, T. J., Taylor, J. S., Dutta, S. n., Lorenz, H. P., Bruzoni, M. n. 2018


    Benign masses of the eyebrow and forehead are common in pediatric patients and can result in facial asymmetry, discomfort, or super-infection. Excision is classically conducted via an incision directly over the mass, which can produce sub-optimal cosmesis. Recently, an endoscopic approach using pediatric brow-lift equipment has been adopted. We reviewed our center's experience with endoscopic removal of benign facial lesions and compared these cases with an equivalent series of open cases.A retrospective chart review was conducted to identify pediatric cases of endoscopic and open removal of benign eyebrow or forehead lesions at our institution from 2009 to 2016. Clinical and cosmetic outcomes were reviewed.A total of 40 endoscopic and 25 open cases of excision of benign facial lesions in children were identified. For the patients who underwent endoscopic excision, the majority (85%) presented with a cyst located at the eyebrow. Histologic examination revealed 36 dermoid cysts (90%), 2 epidermal cysts, and 2 pilomatrixomas. Of the 36 cases with post-operative follow-up, 32 patients (89%) had an uncomplicated recovery with good cosmesis. Two patients had an eyebrow droop that resolved without intervention. One patient had localized numbness overlying the site, but no motor deficits. One patient presented with a recurrent dermoid cyst that required open resection. For the patients who underwent open excision, the majority (52%) had dermoid cysts located at the eyebrow. Of the 22 cases with follow-up, 20 of the patients had an uncomplicated recovery (90%). Comparing the rate of complications, there was no statistically significant difference between the two groups (P = 1.0).Endoscopic excision of benign forehead and eyebrow lesions in pediatric patients is feasible and yields excellent cosmetic results. When compared with open excision, complication rates are similar between both approaches and a facial scar can be avoided with an endoscopic approach.

    View details for PubMedID 29446701

  • Safety and Wound Outcomes Following Genetically Corrected Autologous Epidermal Grafts in Patients With Recessive Dystrophic Epidermolysis Bullosa. JAMA Siprashvili, Z., Nguyen, N. T., Gorell, E. S., Loutit, K., Khuu, P., Furukawa, L. K., Lorenz, H. P., Leung, T. H., Keene, D. R., Rieger, K. E., Khavari, P., Lane, A. T., Tang, J. Y., Marinkovich, M. P. 2016; 316 (17): 1808-1817


    Recessive dystrophic epidermolysis bullosa (RDEB) is a devastating, often fatal, inherited blistering disorder caused by mutations in the COL7A1 gene encoding type VII collagen. Support and palliation are the only current therapies.To evaluate the safety and wound outcomes following genetically corrected autologous epidermal grafts in patients with RDEB.Single-center phase 1 clinical trial conducted in the United States of 4 patients with severe RDEB with a measured area of wounds suitable for grafting of at least 100 cm2. Patients with undetectable type VII collagen keratinocyte expression were excluded.Autologous keratinocytes isolated from biopsy samples collected from 4 patients with RDEB were transduced with good manufacturing practice-grade retrovirus carrying full-length human COL7A1 and assembled into epidermal sheet grafts. Type VII collagen gene-corrected grafts (approximately 35 cm2) were transplanted onto 6 wounds in each of the patients (n = 24 grafts).The primary safety outcomes were recombination competent retrovirus, cancer, and autoimmune reaction. Molecular correction was assessed as type VII collagen expression measured by immunofluorescence and immunoelectron microscopy. Wound healing was assessed using serial photographs taken at 3, 6, and 12 months after grafting.The 4 patients (mean age, 23 years [range, 18-32 years]) were all male with an estimated body surface area affected with RDEB of 4% to 30%. All 24 grafts were well tolerated without serious adverse events. Type VII collagen expression at the dermal-epidermal junction was demonstrated on the graft sites by immunofluorescence microscopy in 9 of 10 biopsy samples (90%) at 3 months, in 8 of 12 samples (66%) at 6 months, and in 5 of 12 samples (42%) at 12 months, including correct type VII collagen localization to anchoring fibrils. Wounds with recombinant type VII collagen graft sites displayed 75% or greater healing at 3 months (21 intact graft sites of 24 wound sites; 87%), 6 months (16/24; 67%), and 12 months (12/24; 50%) compared with baseline wound sites.In this preliminary study of 4 patients with RDEB, there was wound healing in some type VII collagen gene-corrected grafts, but the response was variable among patients and among grafted sites and generally declined over 1 year. Long-term follow-up is necessary for these patients, and controlled trials are needed with a broader range of patients to better understand the potential long-term efficacy of genetically corrected autologous epidermal Identifier: NCT01263379.

    View details for DOI 10.1001/jama.2016.15588

    View details for PubMedID 27802546

  • Expansion and Hepatic Differentiation of Adult Blood-Derived CD34(+) Progenitor Cells and Promotion of Liver Regeneration After Acute Injury STEM CELLS TRANSLATIONAL MEDICINE Hu, M., Li, S., Menon, S., Liu, B., Hu, M. S., Longaker, M. T., Lorenz, H. P. 2016; 5 (6): 723-732


    The low availability of functional hepatocytes has been an unmet demand for basic scientific research, new drug development, and cell-based clinical applications for decades. Because of the inability to expand hepatocytes in vitro, alternative sources of hepatocytes are a focus of liver regenerative medicine. We report a new group of blood-derived CD34(+) progenitor cells (BDPCs) that have the ability to expand and differentiate into functional hepatocyte-like cells and promote liver regeneration. BDPCs were obtained from the peripheral blood of an adult mouse with expression of surface markers CD34, CD45, Sca-1, c-kit, and Thy1.1. BDPCs can proliferate in vitro and differentiate into hepatocyte-like cells expressing hepatocyte markers, including CK8, CK18, CK19, α-fetoprotein, integrin-β1, and A6. The differentiated BDPCs (dBDPCs) also display liver-specific functional activities, such as glycogen storage, urea production, and albumin secretion. dBDPCs have cytochrome P450 activity and express specific hepatic transcription factors, such as hepatic nuclear factor 1α. To demonstrate liver regenerative activity, dBDPCs were injected into mice with severe acute liver damage caused by a high-dose injection of carbon tetrachloride (CCl4). dBDPC treatment rescued the mice from severe acute liver injury, increased survival, and induced liver regeneration. Because of their ease of access and application through peripheral blood and their capability of rapid expansion and hepatic differentiation, BDPCs have great potential as a cell-based therapy for liver disease.Hematopoietic stem/progenitor cell expansion and tissue-specific differentiation in vitro are challenges in regenerative medicine, although stem cell therapy has raised hope for the treatment of liver diseases by overcoming the scarcity of hepatocytes. This study identified and characterized a group of blood-derived progenitor cells (BDPCs) from the peripheral blood of an adult mouse. The CD34(+) progenitor-dominant BDPCs were rapidly expanded and hepatically differentiated into functional hepatocyte-like cells with our established coculture system. BDPC treatment increased animal survival and produced full regeneration in a severe liver injury mouse model caused by CCl4. BDPCs could have potential for liver cell therapies.

    View details for DOI 10.5966/sctm.2015-0268

    View details for PubMedID 27075766

    View details for PubMedCentralID PMC4878335

  • Skin fibrosis. Identification and isolation of a dermal lineage with intrinsic fibrogenic potential. Science Rinkevich, Y., Walmsley, G. G., Hu, M. S., Maan, Z. N., Newman, A. M., Drukker, M., Januszyk, M., Krampitz, G. W., Gurtner, G. C., Lorenz, H. P., Weissman, I. L., Longaker, M. T. 2015; 348 (6232)


    Dermal fibroblasts represent a heterogeneous population of cells with diverse features that remain largely undefined. We reveal the presence of at least two fibroblast lineages in murine dorsal skin. Lineage tracing and transplantation assays demonstrate that a single fibroblast lineage is responsible for the bulk of connective tissue deposition during embryonic development, cutaneous wound healing, radiation fibrosis, and cancer stroma formation. Lineage-specific cell ablation leads to diminished connective tissue deposition in wounds and reduces melanoma growth. Using flow cytometry, we identify CD26/DPP4 as a surface marker that allows isolation of this lineage. Small molecule-based inhibition of CD26/DPP4 enzymatic activity during wound healing results in diminished cutaneous scarring. Identification and isolation of these lineages hold promise for translational medicine aimed at in vivo modulation of fibrogenic behavior.

    View details for DOI 10.1126/science.aaa2151

    View details for PubMedID 25883361

    View details for PubMedCentralID PMC5088503

  • Peripheral blood-derived mesenchymal stem cells: candidate cells responsible for healing critical-sized calvarial bone defects. Stem cells translational medicine Li, S., Huang, K., Wu, J., Hu, M. S., Sanyal, M., Hu, M., Longaker, M. T., Lorenz, H. P. 2015; 4 (4): 359-368


    Postnatal tissue-specific stem/progenitor cells hold great promise to enhance repair of damaged tissues. Many of these cells are retrieved from bone marrow or adipose tissue via invasive procedures. Peripheral blood is an ideal alternative source for the stem/progenitor cells because of its ease of retrieval. We present a coculture system that routinely produces a group of cells from adult peripheral blood. Treatment with these cells enhanced healing of critical-size bone defects in the mouse calvarium, a proof of principle that peripheral blood-derived cells can be used to heal bone defects. From these cells, we isolated a subset of CD45(-) cells with a fibroblastic morphology. The CD45(-) cells were responsible for most of the differentiation-induced calcification activity and were most likely responsible for the enhanced healing process. These CD45(-) fibroblastic cells are plastic-adherent and exhibit a surface marker profile negative for CD34, CD19, CD11b, lineage, and c-kit and positive for stem cell antigen 1, CD73, CD44, CD90.1, CD29, CD105, CD106, and CD140α. Furthermore, these cells exhibited osteogenesis, chondrogenesis, and adipogenesis capabilities. The CD45(-) fibroblastic cells are the first peripheral blood-derived cells that fulfill the criteria of mesenchymal stem cells as defined by the International Society for Cellular Therapy. We have named these cells "blood-derived mesenchymal stem cells."

    View details for DOI 10.5966/sctm.2014-0150

    View details for PubMedID 25742693

    View details for PubMedCentralID PMC4367504

  • Scarless wound healing: chasing the holy grail. Plastic and reconstructive surgery Walmsley, G. G., Maan, Z. N., Wong, V. W., Duscher, D., Hu, M. S., Zielins, E. R., Wearda, T., Muhonen, E., McArdle, A., Tevlin, R., Atashroo, D. A., Senarath-Yapa, K., Lorenz, H. P., Gurtner, G. C., Longaker, M. T. 2015; 135 (3): 907-917


    Over 100 million patients acquire scars in the industrialized world each year, primarily as a result of elective operations. Although undefined, the global incidence of scarring is even larger, extending to significant numbers of burn and other trauma-related wounds. Scars have the potential to exert a profound psychological and physical impact on the individual. Beyond aesthetic considerations and potential disfigurement, scarring can result in restriction of movement and reduced quality of life. The formation of a scar following skin injury is a consequence of wound healing occurring through reparative rather than regenerative mechanisms. In this article, the authors review the basic stages of wound healing; differences between adult and fetal wound healing; various mechanical, genetic, and pharmacologic strategies to reduce scarring; and the biology of skin stem/progenitor cells that may hold the key to scarless regeneration.

    View details for DOI 10.1097/PRS.0000000000000972

    View details for PubMedID 25719706

  • Fetal Mouse Skin Heals Scarlessly in a Chick Chorioallantoic Membrane Model System ANNALS OF PLASTIC SURGERY Carre, A. L., Larson, B. J., Knowles, J. A., Kawai, K., Longaker, M. T., Lorenz, H. P. 2012; 69 (1): 85-90


    In mammals, the early-gestation fetus has the regenerative ability to heal skin wounds without scar formation. This observation was first reported more than 3 decades ago, and has been confirmed in a number of in vivo animal models. Although an intensive research effort has focused on unraveling the mechanisms underlying scarless fetal wound repair, no suitable model of in vitro fetal skin healing has been developed. In this article, we report a novel model for the study of fetal wound healing. Fetal skin from gestational day 16.5 Balb/c mice (total gestation, 20 days) was grafted onto the chorioallantoic membrane of 12-day-old chicken embryos and cultured for up to 7 days. At 48 hours postengraftment, circular wounds (diameter = 1 mm) were made in the fetal skin using a rotating titanium sapphire laser (N = 45). The tissue was examined daily by visual inspection to look for signs of infection and ischemia. The grafts and the surrounding host tissue were examined histologically. In all fetal skin grafts, the wounds completely reepithelialized by postinjury day 7, with regeneration of the dermis. Fetal mouse skin xenografts transplanted onto the chorioallantoic membrane of fertilized chicken eggs provides a useful model for the study of fetal wound healing. This model can be used as an adjunct to traditional in vivo mammalian models of fetal repair.

    View details for DOI 10.1097/SAP.0b013e31822128a9

    View details for Web of Science ID 000305485200020

    View details for PubMedID 21712703

  • Outcomes of Complex Abdominal Herniorrhaphy Experience With 106 Cases ANNALS OF PLASTIC SURGERY Satterwhite, T. S., Miri, S., Chung, C., Spain, D., Lorenz, H. P., Lee, G. K. 2012; 68 (4): 382-388


    Reconstruction of abdominal wall defects is a challenging problem. Often, the surgeon is presented with a patient having multiple comorbidities, who has already endured numerous unsuccessful operations, leaving skin and fascia that are attenuated and unreliable. Our study investigated preoperative, intraoperative, and postoperative factors and techniques during abdominal wall reconstruction to determine which variables were associated with poor outcomes.Data were collected on all patients who underwent ventral abdominal hernia repair by 3 senior-level surgeons at our institution during an 8-year period. In all cases, placement of either a synthetic or a biologic mesh was used to provide additional reinforcement of the repair.A total of 106 patients were included. Seventy-nine patients (75%) had preoperative comorbid conditions. Sixty-seven patients developed a postoperative complication (63%). Skin necrosis was the most common complication (n = 21, 19.8%). Other complications included seroma (n = 19, 17.9%), cellulitis (n = 19, 17.9%), abscess (n = 14 13.2%), pulmonary embolus/deep vein thrombosis (n = 3, 2.8%), small bowel obstruction (n = 2, 1.9%), and fistula (n = 8, 7.5%). Factors that significantly contributed to postoperative complications (P < 0.05) included obesity, diabetes, hypertension, fistula at the time of the operation, a history of >2 prior hernia repairs, a history of >3 prior abdominal operations, hospital stay for >14 days, defect size > 300 square cm, and the use of human-derived mesh allograft. Factors that significantly increased the likelihood of a hernia recurrence (P < 0.05) included a history of >2 prior hernia repairs, the use of human-derived allograft, using an overlay-only mesh placement, and the presence of a postoperative complication, particularly infection. Hernia recurrences were significantly reduced (P < 0.05) by using a "sandwich" repair with both a mesh overlay and underlay and by using component separation.A history of multiple abdominal operations is a major predictor of complications and recurrences. If needed, component separation should be used to achieve primary tension-free closure, which helps to reduce the likelihood of hernia recurrences. Our data suggest that mesh reinforcement used concomitantly in a "sandwich" repair with component separation release may lead to reduced recurrence rates and may provide the optimal repair in complex hernia defects.

    View details for DOI 10.1097/SAP.0b013e31823b68b1

    View details for Web of Science ID 000301800600013

    View details for PubMedID 22421484

  • Calcium-Based Nanoparticles Accelerate Skin Wound Healing PLOS ONE Kawai, K., Larson, B. J., Ishise, H., Carre, A. L., Nishimoto, S., Longaker, M., Lorenz, H. P. 2011; 6 (11)


    Nanoparticles (NPs) are small entities that consist of a hydroxyapatite core, which can bind ions, proteins, and other organic molecules from the surrounding environment. These small conglomerations can influence environmental calcium levels and have the potential to modulate calcium homeostasis in vivo. Nanoparticles have been associated with various calcium-mediated disease processes, such as atherosclerosis and kidney stone formation. We hypothesized that nanoparticles could have an effect on other calcium-regulated processes, such as wound healing. In the present study, we synthesized pH-sensitive calcium-based nanoparticles and investigated their ability to enhance cutaneous wound repair.Different populations of nanoparticles were synthesized on collagen-coated plates under various growth conditions. Bilateral dorsal cutaneous wounds were made on 8-week-old female Balb/c mice. Nanoparticles were then either administered intravenously or applied topically to the wound bed. The rate of wound closure was quantified. Intravenously injected nanoparticles were tracked using a FLAG detection system. The effect of nanoparticles on fibroblast contraction and proliferation was assessed.A population of pH-sensitive calcium-based nanoparticles was identified. When intravenously administered, these nanoparticles acutely increased the rate of wound healing. Intravenously administered nanoparticles were localized to the wound site, as evidenced by FLAG staining. Nanoparticles increased fibroblast calcium uptake in vitro and caused contracture of a fibroblast populated collagen lattice in a dose-dependent manner. Nanoparticles also increased the rate of fibroblast proliferation.Intravenously administered, calcium-based nanoparticles can acutely decrease open wound size via contracture. We hypothesize that their contraction effect is mediated by the release of ionized calcium into the wound bed, which occurs when the pH-sensitive nanoparticles disintegrate in the acidic wound microenvironment. This is the first study to demonstrate that calcium-based nanoparticles can have a therapeutic benefit, which has important implications for the treatment of wounds.

    View details for DOI 10.1371/journal.pone.0027106

    View details for Web of Science ID 000297154900079

    View details for PubMedID 22073267

    View details for PubMedCentralID PMC3206933

  • Scarless Fetal Wound Healing: A Basic Science Review PLASTIC AND RECONSTRUCTIVE SURGERY Larson, B. J., Longaker, M. T., Lorenz, H. P. 2010; 126 (4): 1172-1180


    Scar formation is a major medical problem that can have devastating consequences for patients. The adverse physiological and psychological effects of scars are broad, and there are currently no reliable treatments to prevent scarring. In contrast to adult wounds, early gestation fetal skin wounds repair rapidly and in the absence of scar formation. Despite extensive investigation, the exact mechanisms of scarless fetal wound healing remain largely unknown. For some time, it has been known that significant differences exist among the extracellular matrix, inflammatory response, cellular mediators, and gene expression profiles of fetal and postnatal wounds. These differences may have important implications in scarless wound repair.

    View details for DOI 10.1097/PRS.0b013e3181eae781

    View details for Web of Science ID 000282559100004

    View details for PubMedID 20885241

  • Airway Analysis: With Bilateral Distraction of the Infant Mandible JOURNAL OF CRANIOFACIAL SURGERY Looby, J. F., Schendel, S. A., Lorenz, H. P., Hopkins, E. M., Aizenbud, D. 2009; 20 (5): 1341-1346


    Mandibular distraction was proven to be a valuable tool for lengthening the hypoplastic mandible and relieving airway obstruction in infants. However, analysis of presurgical and postsurgical three-dimensional computed tomography and polysomnogram studies is lacking. The aim of this study was to describe the effect of distraction on the airway by evaluating the clinical, three-dimensional radiographic and polysomnogram studies before and after distraction.Seventeen infants with micrognathia who underwent internal curvilinear mandibular distraction from April 2005 through April 2008 at Lucile Packard Children's Hospital were included. Preoperative and postoperative computed tomography, polysomnograms, and feeding evaluations were obtained and compared after distraction.The mean patient age before surgery was 105 days. All patients tolerated the distraction process with a mean mandibular advancement of 18.1 mm. One patient experienced a temporary marginal mandibular nerve palsy that resolved, and 1 postoperative wound infection was encountered. Preoperatively, the mean retroglossal oropharyngeal cross-sectional area was 41.53 mm. This was associated with a mean preoperative apnea-hypopnea index (AHI) of 10.57 and a minimum oxygen desaturation of 83%. After distraction, the mean airway increased to 127.77 mm. All patients had clinical improvement of their respiratory status; the mean postoperative AHI was 2.21, and the minimum oxygen desaturation was 90%. The result was a 209% cross-sectional airway increase. All patients progressed to oral feeds by 3.5 months postoperatively.Mandibular distraction is effective at relieving anatomic airway obstruction in infants with micrognathia and obstructive sleep apnea while avoiding some previously reported associated complications.

    View details for DOI 10.1097/SCS.0b013e3181ae4139

    View details for Web of Science ID 000270369000008

    View details for PubMedID 19816252

  • Current Applications and Safety of Autologous Fat Grafts: A Report of the ASPS Fat Graft Task Force PLASTIC AND RECONSTRUCTIVE SURGERY Gutowski, K. A. 2009; 124 (1): 272-280


    TASK FORCE STATEMENT: In 2007, the American Society of Plastic Surgeons formed a task force to conduct an assessment regarding the safety and efficacy of autologous fat grafting, specifically to the breast, and to make recommendations for future research. The task force formulated specific issues regarding fat grafting and then compiled them to focus on five broad-based questions: 1. What are the current and potential applications of fat grafting (specifically breast indications, and if data are available, other cosmetic and reconstructive applications)? 2. What risks and complications are associated with fat grafting? 3. How does technique affect outcomes, including safety and efficacy, of fat grafting? 4. What risk factors need to be considered for patient selection at this level of invasiveness? 5. What advancements in bench research/molecular biology potentially impact current or future methods of fat grafting? To answer these questions, the task force reviewed the scientific literature, critically appraised the information available, and developed evidence-based practice recommendations. Although the primary issue of interest was fat grafting to the breast, other aspects of fat grafting were evaluated.

    View details for DOI 10.1097/PRS.0b013e3181a09506

    View details for Web of Science ID 000267895000035

    View details for PubMedID 19346997

  • Identification of differentially regulated genes in fetal wounds during regenerative repair WOUND REPAIR AND REGENERATION Colwell, A. S., Longaker, M. T., Lorenz, H. P. 2008; 16 (3): 450-459


    During mammalian skin development, wounds heal with regeneration rather than scar. Genomic microarray analysis of fetal (scarless) and postnatal (scarring) cutaneous wounds was performed to identify genes with differential expression and possible proregenerative function. Differentially expressed genes between the scarless and scarring wound transcriptomes were identified with significance analysis of microarrays. At early time points, the fraction of genes with increased expression was greater in the fetal wounds. Conversely, as time after injury increased, the fraction of genes with increased expression in postnatal wounds increased from 0% at 1 hour to 67% at 24 hours. The fetal 1- and 12-hour wound transcriptomes identified genes important in DNA transcription and repair, cell cycle regulation, protein homeostasis, and intracellular signaling. The predominant expression patterns of these genes from 1 to 24 hours predominantly revealed rapid up-regulation, followed by declining expression at 24 hours. Fewer genes with differential expression between the fetal scarless and postnatal scarring wound transcriptomes were identified at 24 hours, most of which had greater expression in the postnatal wound. Our data suggest that multiple gene products may be necessary for the coordination of skin regeneration during wound repair in the fetus.

    View details for DOI 10.1111/j.1524-475X.2008.00383.x

    View details for Web of Science ID 000255666500016

    View details for PubMedID 18471263

  • Current treatment of craniosynostosis and future therapeutic directions. Frontiers of oral biology Wan, D. C., Kwan, M. D., Lorenz, H. P., Longaker, M. T. 2008; 12: 209-230


    Normal craniofacial development is contingent upon coordinated growth between the brain and overlying calvaria. Craniosynostosis, the premature fusion of one or more cranial sutures, perturbs this natural framework, resulting in dramatic dysmorphology of the skull and face along with a multitude of associated functional abnormalities. Traditional approaches to the treatment of craniosynostosis have employed complex surgical remodeling of the skull vault and facial deformities all aimed at increasing the amount of intracranial volume and restoring a more normal craniofacial appearance. Significant morbidity and mortality, however, have plagued these procedures, driving dramatic evolution in our approach towards the treatment of pathologically fused sutures. Recent clinical and genetic studies have identified multiple forms of human craniosynostosis, each associated with mutations within various cytokine signaling pathways. Knowledge garnered from these investigations bear promise for the future development of alternative strategies to enhance or perhaps even replace contemporary approaches for the treatment of craniosynostosis.

    View details for DOI 10.1159/0000115043

    View details for PubMedID 18391503

  • Enhanced Recovery After Cleft Palate Repair: A Quality Improvement Project. Paediatric anaesthesia Esfahanian, M., Marcott, S. C., Hopkins, E., Burkart, B., Khosla, R., Lorenz, H. P., Wang, E., De Souza, E., Algaze-Yojay, C., Caruso, T. J. 2022


    BACKGROUND: Children undergoing cleft palate repair present challenges to postoperative management due to several factors that can complicate recovery. Utilization of multimodal analgesic protocols can improve outcomes in this population. We report experience designing and implementing an enhanced recovery after surgery (ERAS) pathway for cleft palate repair to optimize postoperative recovery.AIMS: The primary aim was to implement an ERAS pathway with >70% bundle adherence to achieve a 30% reduction in postoperative opioid consumption within 12 months. Our secondary aims assessed intraoperative opioid consumption, length of stay (LOS), timeliness of oral intake, and respiratory recovery.METHODS: A multidisciplinary team of perioperative providers developed an ERAS pathway for cleft palate patients. Key drivers included patient and provider education, formal pathway creation and implementation, multimodal pain therapy, and target-based care. Interventions included maxillary nerve blockade and enhanced intra- and postoperative medication regimens. Outcomes were displayed as statistical process control charts.RESULTS: Pathway compliance was 77.0%. Patients during the intervention period (n=39) experienced a 49% reduction in postoperative opioid consumption (p<0.0001) relative to our historical cohort (n=63), with a mean difference of -0.33 ±0.11 mg/kg (95% CI -0.55 to -0.12 mg/kg). Intraoperative opioid consumption was reduced by 36% (p=0.002), with a mean difference of -0.27 ±0.09 mg/kg (95% CI -0.45 to -0.09 mg/kg). Additionally, patients in the intervention group had a 45% reduction in time to first oral intake (p=0.02) relative to our historical cohort, with a mean difference of -3.81 ±1.56 hours (95% CI -6.9 to -0.70). There was no difference in PACU or hospital LOS, but there was a significant reduction in variance of all secondary outcomes.CONCLUSION: Opioid reduction and improved timeliness of oral intake is possible with an ERAS protocol for cleft palate repair, but our protocol did not alter PACU or hospital LOS.

    View details for DOI 10.1111/pan.14541

    View details for PubMedID 35929340

  • A Novel Xenograft Model Demonstrates Human Fibroblast Behavior During Skin Wound Repair and Fibrosis. Advances in wound care Borrelli, M., Shen, A. H., Griffin, M., Mascharak, S., Adem, S., Diaz Deleon, N. M., Ngaage, L. M., Longaker, M. T., Wan, D. C., Lorenz, H. P. 2021


    OBJECTIVE: Xenografts of human skin on immunodeficient mice provide a means of assessing human skin physiology and its response to wounding.APPROACH: We describe a novel xenograft model using full-thickness human neonatal foreskin to examine human skin wound repair and fibroblast heterogeneity. Full-thickness 8-mm human neonatal foreskin biopsies were sutured into the dorsum of NSG (NOD.Cg-Prkdc scidIl2rgtm1Wjl/SzJ) pups as subcutaneous grafts and exposed to cutaneous grafts at the time of weaning (postnatal day 21). To model fibrosis, xenografts were wounded with 5-mm linear incisions and monitored until post-wound day (PWD) 14. To explore whether our model can be used to test the efficacy of topical therapies, wounded xenografts were injected with fibroblast growth factor-2 (FGF2) for the first four consecutive PWDs. Xenografts were harvested for analysis by histology and fluorescence-activated cell sorting (FACS).RESULTS: Xenografts successfully engrafted with evidence of mouse-human anastomoses and resembled native neonatal foreskin at the gross and microscopic level. Wounded xenografted skin scarred with human collagen and an expansion of CD26-positive human fibroblasts. Collagen scar was quantitated by neural network analysis, which revealed distinct clustering of collagen fiber networks from unwounded skin and wounded skin at PWD7 and PWD14. Collagen fiber networks within FGF2-treated wounds at PWD14 resembled those in untreated wounded xenografts at PWD7, suggesting that FGF2 treatment at time of wounding can reduce fibrosis. Innovation and Conclusion: This novel xenograft model can be used to investigate acute fibrosis, fibroblast heterogeneity, and the efficacy of antifibrotic agents during wound repair in human skin.

    View details for DOI 10.1089/wound.2020.1392

    View details for PubMedID 34521222

  • Standardizing dimensionless cutometer parameters to determine in-vivo elasticity of human skin. Advances in wound care Abbas, D. B., Lavin, C., Fahy, E., Griffin, M., Guardino, N., King, M., Chen, K., Lorenz, H. P., Gurtner, G. C., Longaker, M. T., Momeni, A., Wan, D. C. 2021


    OBJECTIVE: Skin fibrosis places an enormous burden on patients and society, but disagreement exists over methods to quantify severity of skin scarring. A suction cutometer measures skin elasticity in-vivo, but it has not been widely adopted due to inconsistency in data produced. We investigated variability of several dimensionless parameters generated by the cutometer to improve their precision and accuracy.APPROACH: Twenty adult human subjects underwent suction cutometer measurement of normal skin and fibrotic scars. Using Mode 1, each subject underwent 5 trials with each trial containing 4 curves. R0/2/5/6/7 and Q1/2/3 data were collected. Analyses were performed on these calculated parameters.RESULTS: R0/2/5/6/7 and Q1/2 parameters from curves 1-4 demonstrated significant differences, while these same parameters were not significantly different when only using curves 2-4. Individual analysis of all parameters between curve 1 and every subsequent curve was statistically significant for R0, R2, R5, R6, R7, Q1, and Q2. No differences were appreciated for parameter Q3. Comparison between normal skin and fibrotic scars were significantly different for parameters R5, Q1, and Q3.INNOVATION: Our study is the first demonstration of accurate comparison between normal skin and fibrotic scars using the dimensionless parameters of a suction cutometer.CONCLUSION: Measured parameters from the first curve of each trial were significantly different from subsequent curves for both normal skin and fibrotic scars. Precision and reproducibility of data from dimensionless parameters can therefore be improved by removing the first curve. R5, Q1, and Q3 parameters differentiated normal skin as more elastic than fibrotic scars.

    View details for DOI 10.1089/wound.2021.0082

    View details for PubMedID 34470542

  • JUN promotes hypertrophic skin scarring via CD36 in preclinical in vitro and in vivo models. Science translational medicine Griffin, M. F., Borrelli, M. R., Garcia, J. T., Januszyk, M., King, M., Lerbs, T., Cui, L., Moore, A. L., Shen, A. H., Mascharak, S., Diaz Deleon, N. M., Adem, S., Taylor, W. L., desJardins-Park, H. E., Gastou, M., Patel, R. A., Duoto, B. A., Sokol, J., Wei, Y., Foster, D., Chen, K., Wan, D. C., Gurtner, G. C., Lorenz, H. P., Chang, H. Y., Wernig, G., Longaker, M. T. 2021; 13 (609): eabb3312


    [Figure: see text].

    View details for DOI 10.1126/scitranslmed.abb3312

    View details for PubMedID 34516825

  • Readability of Online Patient Information Relating to Cleft Palate Surgery. The Cleft palate-craniofacial journal : official publication of the American Cleft Palate-Craniofacial Association Lavin, C. V., Fahy, E. J., Abbas, D. B., Griffin, M., Deleon, N. M., Lee, D. K., Khosla, R. K., Bruckman, K., Lorenz, H. P., Wan, D. C. 2021: 10556656211013177


    OBJECTIVE: It is important for health care education materials to be easily understood by caretakers of children requiring craniofacial surgery. This study aimed to analyze the readability of Google search results as they pertain to "Cleft Palate Surgery" and "Palatoplasty." Additionally, the study included a search from several locations globally to identify possible geographic differences.DESIGN: Google searches of the terms "Cleft Palate Surgery" and "Palatoplasty" were performed. Additionally, searches of only "Cleft Palate Surgery" were run from several internet protocol addresses globally.MAIN OUTCOME MEASURES: Flesch-Kincaid Grade Level and Readability Ease, Gunning Fog Index, Simple Measure of Gobbledygook (SMOG) index, and Coleman-Liau Index.RESULTS: Search results for "Cleft Palate Surgery" were easier to read and comprehend compared to search results for "Palatoplasty." Mean Flesch-Kincaid Grade Level scores were 7.0 and 10.11, respectively (P = .0018). Mean Flesch-Kincaid Reading Ease scores were 61.29 and 40.71, respectively (P = .0003). Mean Gunning Fog Index scores were 8.370 and 10.34, respectively (P = .0458). Mean SMOG Index scores were 6.84 and 8.47, respectively (P = .0260). Mean Coleman-Liau Index scores were 12.95 and 15.33, respectively (P = .0281). No significant differences were found in any of the readability measures based on global location.CONCLUSIONS: Although some improvement can be made, craniofacial surgeons can be confident in the online information pertaining to cleft palate repair, regardless of where the search is performed from. The average readability of the top search results for "Cleft Palate Surgery" is around the seventh-grade reading level (US educational system) and compares favorably to other health care readability analyses.

    View details for DOI 10.1177/10556656211013177

    View details for PubMedID 33960204

  • Preventing Engrailed-1 activation in fibroblasts yields wound regeneration without scarring. Science (New York, N.Y.) Mascharak, S., desJardins-Park, H. E., Davitt, M. F., Griffin, M., Borrelli, M. R., Moore, A. L., Chen, K., Duoto, B., Chinta, M., Foster, D. S., Shen, A. H., Januszyk, M., Kwon, S. H., Wernig, G., Wan, D. C., Lorenz, H. P., Gurtner, G. C., Longaker, M. T. 2021; 372 (6540)


    Skin scarring, the end result of adult wound healing, is detrimental to tissue form and function. Engrailed-1 lineage-positive fibroblasts (EPFs) are known to function in scarring, but Engrailed-1 lineage-negative fibroblasts (ENFs) remain poorly characterized. Using cell transplantation and transgenic mouse models, we identified a dermal ENF subpopulation that gives rise to postnatally derived EPFs by activating Engrailed-1 expression during adult wound healing. By studying ENF responses to substrate mechanics, we found that mechanical tension drives Engrailed-1 activation via canonical mechanotransduction signaling. Finally, we showed that blocking mechanotransduction signaling with either verteporfin, an inhibitor of Yes-associated protein (YAP), or fibroblast-specific transgenic YAP knockout prevents Engrailed-1 activation and promotes wound regeneration by ENFs, with recovery of skin appendages, ultrastructure, and mechanical strength. This finding suggests that there are two possible outcomes to postnatal wound healing: a fibrotic response (EPF-mediated) and a regenerative response (ENF-mediated).

    View details for DOI 10.1126/science.aba2374

    View details for PubMedID 33888614

  • Prrx1 Fibroblasts Represent a Pro-fibrotic Lineage in the Mouse Ventral Dermis. Cell reports Leavitt, T., Hu, M. S., Borrelli, M. R., Januszyk, M., Garcia, J. T., Ransom, R. C., Mascharak, S., desJardins-Park, H. E., Litzenburger, U. M., Walmsley, G. G., Marshall, C. D., Moore, A. L., Duoto, B., Adem, S., Foster, D. S., Salhotra, A., Shen, A. H., Griffin, M., Shen, E. Z., Barnes, L. A., Zielins, E. R., Maan, Z. N., Wei, Y., Chan, C. K., Wan, D. C., Lorenz, H. P., Chang, H. Y., Gurtner, G. C., Longaker, M. T. 2020; 33 (6): 108356


    Fibroblast heterogeneity has been shown within the unwounded mouse dorsal dermis, with fibroblast subpopulations being identified according to anatomical location and embryonic lineage. Using lineage tracing, we demonstrate that paired related homeobox 1 (Prrx1)-expressing fibroblasts are responsible for acute and chronic fibroses in the ventral dermis. Single-cell transcriptomics further corroborated the inherent fibrotic characteristics of Prrx1 fibroblasts during wound repair. In summary, we identify and characterize a fibroblast subpopulation in the mouse ventral dermis with intrinsic scar-forming potential.

    View details for DOI 10.1016/j.celrep.2020.108356

    View details for PubMedID 33176144

  • Nationwide Perioperative Analysis of Endoscopic Versus Open Surgery for Craniosynostosis: Equal Access, Unequal Outcomes. The Journal of craniofacial surgery Rochlin, D. H., Sheckter, C. C., Lorenz, H. P., Khosla, R. K. 2020


    The purpose of this study is to evaluate national differences in inpatient outcomes and predictors of treatment type for endoscopic versus open surgery for craniosynostosis, with particular consideration of racial, socioeconomic, and geographic factors. The 2016 Kids' Inpatient Database was queried to identify patients aged 3 years or younger who underwent craniectomy for craniosynostosis. Multivariable regression modeled treatment type based on patient-level (gender, race, income, comorbidities, payer) and facility-level (bed size, region, teaching status) variables, and was used to assess outcomes. The weighted sample included 474 patients, of whom 81.9% (N = 388) of patients underwent open repair and 18.1% (N = 86) underwent endoscopic repair. A total of 81.1% of patients were under 1 year of age and 12.0% were syndromic. Patients were more likely to be treated open if they were older (odds ratio [OR] 3.07, P = 0.005) or syndromic (OR 8.56, P = 0.029). Patients who underwent open repair were more likely to receive transfusions (OR 2.86, P = 0.021), and have longer lengths of stay (OR 1.02, P < 0.001) and more costly hospitalizations (OR 5228.78, P = 0.018). Complications did not significantly vary between procedure type. The authors conclude that United States national data confirm benefits of endoscopic surgery, including a lower risk of transfusion, shorter hospital stay, and lower hospital costs, without a significant change in the rate of inpatient complications. Racial, socioeconomic, and geographic factors were not significantly associated with treatment type or perioperative surgical outcomes. Future studies are needed to further investigate the influence of such variables on access to craniofacial care.

    View details for DOI 10.1097/SCS.0000000000007178

    View details for PubMedID 33055558

  • Stretch marks are abundant in CD26-positive human dermal fibroblasts and exhibit increased profibrotic mechanosensitive signaling Borrelli, M. R., Griffin, M., Ngaage, L. M., Mascharak, S., Lewis, N., Januszyk, M., Wan, D. C., Longaker, M. T., Lorenz, H. P. WILEY. 2020: S32
  • Macrophage Transplantation Fails to Improve Repair of Critical-Sized Calvarial Defects. The Journal of craniofacial surgery Borrelli, M. R., Hu, M. S., Hong, W. X., Oliver, J. D., Duscher, D., Longaker, M. T., Lorenz, H. P. 2019


    INTRODUCTION: Over 500,000 bone grafting procedures are performed every year in the United States for neoplastic and traumatic lesions of the craniofacial skeleton, costing $585 million in medical care. Current bone grafting procedures are limited, and full-thickness critical-sized defects (CSDs) of the adult human skull thus pose a substantial reconstructive challenge for the craniofacial surgeon. Cell-based strategies have been shown to safely and efficaciously accelerate the rate of bone formation in CSDs in animals. The authors recently demonstrated that supraphysiological transplantation of macrophages seeded in pullalan-collagen composite hydrogels significantly accelerated wound healing in wild type and diabetic mice, an effect mediated in part by enhancing angiogenesis. In this study, the authors investigated the bone healing effects of macrophage transplantation into CSDs of mice.METHODS: CD1 athymic nude mice (60 days of age) were anesthetized, and unilateral full-thickness critical-sized (4 mm in diameter) cranial defects were created in the right parietal bone, avoiding cranial sutures. Macrophages were isolated from FVB-L2G mice and seeded onto hydroxyapatite-poly (lactic-co-glycolic acid) (HA-PLGA) scaffolds (1.0 * 10 cells per CSD). Scaffolds were incubated for 24 hours before they were placed into the CSDs. Macrophage survival was assessed using three-dimensional in vivo imaging system (3D IVIS)/micro-CT. Micro-CT at 0, 2, 4, 6, and 8 weeks was performed to evaluate gross bone formation, which was quantified using Adobe Photoshop. Microscopic evidence of bone regeneration was assessed at 8 weeks by histology. Bone formation and macrophage survival were compared at each time point using independent samples t tests.RESULTS: Transplantation of macrophages at supraphysiological concentration had no effect on the formation of bones in CSDs as assessed by either micro-CT data at any time point analyzed (all P > 0.05). These results were corroborated by histology. 3D IVIS/micro-CT demonstrated survival of macrophages through 8 weeks.CONCLUSION: Supraphysiologic delivery of macrophages to CSDs of mice had no effect on bone formation despite survival of transplanted macrophages through to 8 weeks posttransplantation. Further research into the physiological effects of macrophages on bone regeneration is needed to assess whether recapitulation of these conditions in macrophage-based therapy can promote the healing of large cranial defects.

    View details for DOI 10.1097/SCS.0000000000005797

    View details for PubMedID 31609958

  • Intrinsic Chromatin State and Extrinsic Wound-Related Cues Can Coordinate to Activate Fibroblasts for Scarring desJardins-Park, H. E., Moore, A. L., Litzenburger, U., Mascharak, S., Chinta, M., Ransom, R. C., Hu, M. S., Lorenz, H. P., Chang, H. Y., Longaker, M. T. ELSEVIER SCIENCE INC. 2019: S223–S224
  • Tissue Engineering and Regenerative Medicine in Craniofacial Reconstruction and Facial Aesthetics. The Journal of craniofacial surgery Borrelli, M. R., Hu, M. S., Longaker, M. T., Lorenz, H. P. 2019


    The craniofacial region is anatomically complex and is of critical functional and cosmetic importance, making reconstruction challenging. The limitations of current surgical options highlight the importance of developing new strategies to restore the form, function, and esthetics of missing or damaged soft tissue and skeletal tissue in the face and cranium. Regenerative medicine (RM) is an expanding field which combines the principles of tissue engineering (TE) and self-healing in the regeneration of cells, tissues, and organs, to restore their impaired function. RM offers many advantages over current treatments as tissue can be engineered for specific defects, using an unlimited supply of bioengineered resources, and does not require immunosuppression. In the craniofacial region, TE and RM are being increasingly used in preclinical and clinical studies to reconstruct bone, cartilage, soft tissue, nerves, and blood vessels. This review outlines the current progress that has been made toward the engineering of these tissues for craniofacial reconstruction and facial esthetics.

    View details for DOI 10.1097/SCS.0000000000005840

    View details for PubMedID 31369496

  • An Improved Humanized Mouse Model for Excisional Wound Healing Using Double Transgenic Mice ADVANCES IN WOUND CARE Hu, M. S., Cheng, J., Borrelli, M. R., Leavitt, T., Walmsley, G. G., Zielins, E. R., Hong, W., Cheung, A. M., Duscher, D., Maan, Z. N., Irizarry, D. M., Stephan, B., Parsa, F., Wan, D. C., Gurtner, G. C., Lorenz, H., Longaker, M. T. 2018; 7 (1): 11–17


    Objective: Splinting full-thickness cutaneous wounds in mice has allowed for a humanized model of wound healing. Delineating the epithelial edge and assessing time to closure of these healing wounds via macroscopic visualization have remained a challenge. Approach: Double transgenic mice were created by crossbreeding K14-Cre and ROSAmT/mG reporter mice. Full-thickness excisional wounds were created in K14-Cre/ROSAmT/mG mice (n = 5) and imaged using both normal and fluorescent light on the day of surgery, and every other postoperative day (POD) until wound healing was complete. Ten blinded observers analyzed a series of images from a single representative healing wound, taken using normal or fluorescent light, to decide the POD when healing was complete. K14-Cre/ROSAmT/mG mice (n = 4) were subsequently sacrificed at the four potential days of rated wound closure to accurately determine the histological point of wound closure using microscopic fluorescence imaging. Results: Average time to wound closure was rated significantly longer in the wound series images taken using normal light, compared with fluorescent light (mean POD 13.6 vs. 11.6, *p = 0.008). Fluorescence imaging of histological samples indicated that reepithelialization was complete at 12 days postwounding. Innovation: We describe a novel technique, using double transgenic mice K14-Cre/ROSAmT/mG and fluorescence imaging, to more accurately determine the healing time of wounds in mice upon macroscopic evaluation. Conclusion: The accuracy by which wound healing can be macroscopically determined in vivo in mouse models of wound healing is significantly enhanced using K14-Cre/ROSAmT/mG double transgenic mice and fluorescence imaging.

    View details for PubMedID 29344430

  • Pathway Analysis of Gene Expression of E14 Versus E18 Fetal Fibroblasts ADVANCES IN WOUND CARE Hu, M. S., Borrelli, M. R., Januszyk, M., Luan, A., Malhotra, S., Walmsley, G. G., Hong, W., Tevlin, R., Gurtner, G. C., Longaker, M. T., Lorenz, H. P. 2018; 7 (1): 1–10


    Objective: Fetuses early in gestation heal skin wounds without forming scars. The biological mechanisms behind this process are largely unknown. Fibroblasts, however, are cells known to be intimately involved in wound healing and scar formation. We examined fibroblasts in different stages of development to characterize differences in gene expression that may result in the switch from regenerative wound repair to repair with scarring. Approach: Fibroblasts were isolated and cultured from the back skin of BALB/c wild-type mouse fetuses at embryonic day (E)14 and E18 (n = 10). The fibroblast total RNA was extracted, and microarray analysis was conducted using chips containing 42,000 genes. Significance analysis of microarrays was performed to identify genes with greater than twofold expression difference and a false discovery rate of less than two. Identified genes subsequently underwent enrichment analysis to detect differentially expressed pathways. Results: Two hundred seventy-five genes were differentially expressed between E14 and E18 in fetal fibroblasts. Thirty genes were significantly downregulated and 245 genes were significantly upregulated at E18 compared with E14. Ingenuity pathway analysis identified the top 20 signaling pathways differentially activated in fetal fibroblasts between the E18 and E14 time points. Innovation: To our knowledge, this work represents the first instance where differentially expressed genes and signaling pathways between fetal fibroblasts at E14 and E18 have been studied. Conclusion: The genes and pathways identified here potentially underlie the mechanism behind the transition from fetal wound healing via regeneration to wound healing by repair, and may prove to be key targets for future therapeutics.

    View details for PubMedID 29344429

  • Discussion: Towards Microsurgical Correction of Cleft Lip Ex Utero via Restoration of Craniofacial Developmental Programs. Plastic and reconstructive surgery Ransom, R. C., Lorenz, H. P., Longaker, M. T. 2017

    View details for DOI 10.1097/PRS.0000000000003424

    View details for PubMedID 28338583

  • Excess Dermal Tissue Remodeling In Vivo: Does It Settle? Plastic and reconstructive surgery Leavitt, T., Hu, M. S., Zielins, E. R., Barnes, L. A., Marshall, C. D., Wan, D. C., Lorenz, H. P., Gurtner, G. C., Longaker, M. T. 2017; 139 (2): 415e-424e


    Surgical manipulation of skin may result in undesired puckering of excess tissue, which is generally assumed to settle over time. In this article, the authors address the novel question of how this excess tissue remodels.Purse-string sutures (6-0 nylon) were placed at the midline dorsum of 22 wild-type BALB/c mice in a circular pattern marked with tattoo ink. Sutures were cinched and tied under tension in the treatment group, creating an excess tissue deformity, whereas control group sutures were tied without tension. After 2 or 4 weeks, sutures were removed. The area of tattooed skin was measured up to 56 days after suture removal. Histologic analysis was performed on samples harvested 14 days after suture removal.The majority of excess tissue deformities flattened within 2 days after suture removal. However, the sutured skin in the treatment group decreased in area by an average of 18 percent from baseline (n = 9), compared to a 1 percent increase in the control group (n = 10) at 14 days after suture removal (p < 0.05). This was similarly observed at 28 days (treatment, -11.7 percent; control, 4.5 percent; n = 5; p = 0.0243). Despite flattening, deformation with purse-string suture correlated with increased collagen content of skin, in addition to increased numbers of myofibroblasts. Change in area did not correlate with duration of suture placement.Excess dermal tissue deformities demonstrate the ability to remodel with gross flattening of the skin, increased collagen deposition, and incomplete reexpansion to baseline area. Further studies will reveal whether our findings in this mouse model translate to humans.

    View details for DOI 10.1097/PRS.0000000000003026

    View details for PubMedID 28121870

  • Rapid Isolation of BMPR-IB plus Adipose-Derived Stromal Cells for Use in a Calvarial Defect Healing Model JOVE-JOURNAL OF VISUALIZED EXPERIMENTS Marshall, C. D., Zielins, E. R., Brett, E. A., Blackshear, C. P., Hu, M. S., Leavitt, T., Barnes, L. A., Lorenz, H. P., Longaker, M. T., Wan, D. C. 2017


    Invasive cancers, major injuries, and infection can cause bone defects that are too large to be reconstructed with preexisting bone from the patient's own body. The ability to grow bone de novo using a patient's own cells would allow bony defects to be filled with adequate tissue without the morbidity of harvesting native bone. There is interest in the use of adipose-derived stromal cells (ASCs) as a source for tissue engineering because these are obtained from an abundant source: the patient's own adipose tissue. However, ASCs are a heterogeneous population and some subpopulations may be more effective in this application than others. Isolation of the most osteogenic population of ASCs could improve the efficiency and effectiveness of a bone engineering process. In this protocol, ASCs are obtained from subcutaneous fat tissue from a human donor. The subpopulation of ASCs expressing the marker BMPR-IB is isolated using FACS. These cells are then applied to an in vivo calvarial defect healing assay and are found to have improved osteogenic regenerative potential compared with unsorted cells.

    View details for DOI 10.3791/55120

    View details for Web of Science ID 000397847700048

    View details for PubMedID 28287559

  • Sanativo Wound Healing Product Does Not Accelerate Reepithelialization in a Mouse Cutaneous Wound Healing Model. Plastic and reconstructive surgery Marshall, C. D., Hu, M. S., Leavitt, T., Barnes, L. A., Cheung, A. T., Malhotra, S., Lorenz, H. P., Delp, S. L., Quake, S. R., Longaker, M. T. 2017; 139 (2): 343-352


    Sanativo is an over-the-counter Brazilian product derived from Amazon rainforest plant extract that is purported to improve the healing of skin wounds. Two experimental studies have shown accelerated closure of nonsplinted excisional wounds in rat models. However, these models allow for significant contraction of the wound and do not approximate healing in the tight skin of humans.Full-thickness excisional wounds were created on the dorsal skin of mice and were splinted with silicone rings, a model that forces the wound to heal by granulation and reepithelialization. Sanativo or a control solution was applied either daily or every other day to the wounds. Photographs were taken every other day, and the degree of reepithelialization of the wounds was determined.With both daily and every-other-day applications, Sanativo delayed reepithelialization of the wounds. Average time to complete healing was faster with control solution versus Sanativo in the daily application group (9.4 versus 15.2 days; p < 0.0001) and the every-other-day application group (11 versus 13 days; p = 0.017). The size of visible scar at the last time point of the study was not significantly different between the groups, and no differences were found on histologic examination.Sanativo wound healing compound delayed wound reepithelialization in a mouse splinted excisional wound model that approximates human wound healing. The size of visible scar after complete healing was not improved with the application of Sanativo. These results should cast doubt on claims that this product can improve wound healing in humans.

    View details for DOI 10.1097/PRS.0000000000003013

    View details for PubMedID 28121865

  • Scarless wound healing: finding the right cells and signals. Cell and tissue research Leavitt, T., Hu, M. S., Marshall, C. D., Barnes, L. A., Lorenz, H. P., Longaker, M. T. 2016; 365 (3): 483-493


    From the moment we are born, every injury to the skin has the potential to form a scar, many of which can impair form and/or function. As such, scar management constitutes a billion-dollar industry. However, effectively promoting scarless wound healing remains an elusive goal. The complex interactions of wound healing contribute to our inability to recapitulate scarless wound repair as it occurs in nature, such as in fetal skin and the oral mucosa. However, many new advances have occurred in recent years, some of which have translated scientific findings from bench to bedside. In vivo lineage tracing has helped establish a variety of novel cellular culprits that may act as key drivers of the fibrotic response. These newly characterized cell populations present further targets for therapeutic intervention, some of which have previously demonstrated promising results in animal models. Here, we discuss several recent studies that identify exciting approaches for diminishing scar formation. Particular attention will also be paid to the canonical Wnt/β-catenin signaling pathway, which plays an important role in both embryogenesis and tissue repair. New insights into the differential effects of Wnt signaling on heterogeneous fibroblast and keratinocyte populations within the skin further demonstrate methods by which wound healing can be re-directed to a more fetal scarless phenotype. Graphical abstract Recent approaches to reducing scar formation. Representation showing novel scientific approaches for decreasing scar formation, including the targeting of pro-fibrotic cell populations based on surface molecule expression (e.g. DPP4(+) fibroblasts, ADAM12(+) pericytes). Modulation of cellular mechanotransduction pathways are another means to reduce scar formation, both at the molecular level or, macroscopically with dressings designed to offload tension, at cutaneous wound sites (ADAM12 a disintegrin and metalloprotease 12, DPP4 dipeptidyl peptidase-4, FAK focal adhesion kinase).

    View details for DOI 10.1007/s00441-016-2424-8

    View details for PubMedID 27256396

    View details for PubMedCentralID PMC5010960

  • Creation of Abdominal Adhesions in Mice JOVE-JOURNAL OF VISUALIZED EXPERIMENTS Marshall, C. D., Hu, M. S., Leavitt, T., Barnes, L. A., Cheung, A. T., Malhotra, S., Lorenz, H. P., Longaker, M. T. 2016


    Abdominal adhesions consist of fibrotic tissue that forms in the peritoneal space in response to an inflammatory insult, typically surgery or intraabdominal infection. The precise mechanisms underlying adhesion formation are poorly understood. Many compounds and physical barriers have been tested for their ability to prevent adhesions after surgery with varying levels of success. The mouse and rat are important models for the study of abdominal adhesions. Several different techniques for the creation of adhesions in the mouse and rat exist in the literature. Here we describe a protocol utilizing abrasion of the cecum with sandpaper and sutures placed in the right abdominal sidewall. The mouse is anesthetized and the abdomen is prepped. A midline laparotomy is created and the cecum is identified. Sandpaper is used to gently abrade the surface of the cecum. Next, several figure-of-eight sutures are placed into the peritoneum of the right abdominal sidewall. The abdominal cavity is irrigated, a small amount of starch is applied, and the incision is closed. We have found that this technique produces the most consistent adhesions with the lowest mortality rate.

    View details for DOI 10.3791/54450

    View details for Web of Science ID 000391742700091

    View details for PubMedID 27685681

  • Murine Dermal Fibroblast Isolation by FACS JOVE-JOURNAL OF VISUALIZED EXPERIMENTS Walmsley, G. G., Maan, Z. N., Hu, M. S., Atashroo, D. A., Whittam, A. J., Duscher, D., Tevlin, R., Marecic, O., Lorenz, H. P., Gurtner, G. C., Longaker, M. T. 2016


    Fibroblasts are the principle cell type responsible for secreting extracellular matrix and are a critical component of many organs and tissues. Fibroblast physiology and pathology underlie a spectrum of clinical entities, including fibroses in multiple organs, hypertrophic scarring following burns, loss of cardiac function following ischemia, and the formation of cancer stroma. However, fibroblasts remain a poorly characterized type of cell, largely due to their inherent heterogeneity. Existing methods for the isolation of fibroblasts require time in cell culture that profoundly influences cell phenotype and behavior. Consequently, many studies investigating fibroblast biology rely upon in vitro manipulation and do not accurately capture fibroblast behavior in vivo. To overcome this problem, we developed a FACS-based protocol for the isolation of fibroblasts from the dorsal skin of adult mice that does not require cell culture, thereby preserving the physiologic transcriptional and proteomic profile of each cell. Our strategy allows for exclusion of non-mesenchymal lineages via a lineage negative gate (Lin(-)) rather than a positive selection strategy to avoid pre-selection or enrichment of a subpopulation of fibroblasts expressing specific surface markers and be as inclusive as possible across this heterogeneous cell type.

    View details for DOI 10.3791/53430

    View details for Web of Science ID 000368577400023

    View details for PubMedCentralID PMC4781205

  • Mesenchymal Stromal Cells as Cell-Based Therapeutics for Wound Healing STEM CELLS INTERNATIONAL Malhotra, S., Hu, M. S., Marshall, C. D., Leavitt, T., Cheung, A. T., Gonzalez, J. G., Kaur, H., Lorenz, H. P., Longaker, M. T. 2016


    Chronic wounds are a source of substantial morbidity for patients and are a major financial burden for the healthcare system. There are no current therapies that reliably improve nonhealing wounds or reverse pathological scarring. Mesenchymal stromal cells (MSCs) are a promising source of novel cell-based therapies due to the ease of their harvest and their integral role in the native wound repair process. Recent work has addressed the problems of loss of plasticity and off-target delivery through use of modern bioengineering techniques. Here we describe the applications of MSCs harvested from different sources to the wound healing process and recent advances in delivery of MSCs to targeted sites of injury.

    View details for DOI 10.1155/2016/4157934

    View details for Web of Science ID 000373501200001

    View details for PubMedID 26966438

    View details for PubMedCentralID PMC4757746

  • Surveillance of Stem Cell Fate and Function: A System for Assessing Cell Survival and Collagen Expression In Situ TISSUE ENGINEERING PART A Walmsley, G. G., Senarath-Yapa, K., Wearda, T. L., Menon, S., Hu, M. S., Duscher, D., Maan, Z. N., Tsai, J. M., Zielins, E. R., Weissman, I. L., Gurtner, G. C., Lorenz, H. P., Longaker, M. T. 2016; 22 (1-2): 31-40


    Cell-based therapy is an emerging paradigm in skeletal regenerative medicine. However, the primary means by which transplanted cells contribute to bone repair and regeneration remain controversial. To gain an insight into the mechanisms of how both transplanted and endogenous cells mediate skeletal healing, we used a transgenic mouse strain expressing both the topaz variant of green fluorescent protein under the control of the collagen, type I, alpha 1 promoter/enhancer sequence (Col1a1(GFP)) and membrane-bound tomato red fluorescent protein constitutively in all cell types (R26(mTmG)). A comparison of healing in parietal versus frontal calvarial defects in these mice revealed that frontal osteoblasts express Col1a1 to a greater degree than parietal osteoblasts. Furthermore, the scaffold-based application of adipose-derived stromal cells (ASCs), bone marrow-derived mesenchymal stem cells (BM-MSCs), and osteoblasts derived from these mice to critical-sized calvarial defects allowed for investigation of cell survival and function following transplantation. We found that ASCs led to significantly faster rates of bone healing in comparison to BM-MSCs and osteoblasts. ASCs displayed both increased survival and increased Col1a1 expression compared to BM-MSCs and osteoblasts following calvarial defect transplantation, which may explain their superior regenerative capacity in the context of bone healing. Using this novel reporter system, we were able to elucidate how cell-based therapies impact bone healing and identify ASCs as an attractive candidate for cell-based skeletal regenerative therapy. These insights potentially influence stem cell selection in translational clinical trials evaluating cell-based therapeutics for osseous repair and regeneration.

    View details for DOI 10.1089/ten.tea.2015.0221

    View details for Web of Science ID 000368520300005

    View details for PubMedCentralID PMC4741228

  • Emerging drugs for the treatment of wound healing EXPERT OPINION ON EMERGING DRUGS Zielins, E. R., Brett, E. A., Luan, A., Hu, M. S., Walmsley, G. G., Paik, K., Senarath-Yapa, K., Atashroo, D. A., Wearda, T., Lorenz, H. P., Wan, D. C., Longaker, M. T. 2015; 20 (2): 235-246


    Wound healing can be characterized as underhealing, as in the setting of chronic wounds, or overhealing, occurring with hypertrophic scar formation after burn injury. Topical therapies targeting specific biochemical and molecular pathways represent a promising avenue for improving and, in some cases normalizing, the healing process.A brief overview of both normal and pathological wound healing has been provided, along with a review of the current clinical guidelines and treatment modalities for chronic wounds, burn wounds and scar formation. Next, the major avenues for wound healing drugs, along with drugs currently in development, are discussed. Finally, potential challenges to further drug development, and future research directions are discussed.The large body of research concerning wound healing pathophysiology has provided multiple targets for topical therapies. Growth factor therapies with the ability to be targeted for localized release in the wound microenvironment are most promising, particularly when they modulate processes in the proliferative phase of wound healing.

    View details for DOI 10.1517/14728214.2015.1018176

    View details for Web of Science ID 000356118400007

    View details for PubMedID 25704608

  • Chondromyxoid Fibroma of the Mandible in an Adolescent: Case Report and Microsurgical Reconstructive Option CLEFT PALATE-CRANIOFACIAL JOURNAL Khosla, R. K., Nguyen, C., Messner, A. H., Lorenz, P. 2015; 52 (2): 223-228


    Chondromyxoid fibroma is a rare bony tumor that usually presents in the lower extremities of middle-aged adults. Involvement of the craniofacial skeleton is extremely rare. We present the unique case of an adolescent boy with a chondromyxoid fibroma of the mandible. The chondromyxoid fibroma in this patient recurred after initial treatment with curettage. We treated the recurrence with resection of the involved mandible and immediate reconstruction using a vascularized musculo-osseus seventh rib flap ("Eve procedure"). Despite complex reconstruction in adolescents due to skeletal immaturity, the rib flap has successfully grown with the patient up to 3 years postoperatively. Therefore, we believe the musculo-osseus rib flap is a feasible solution for complex ramus and condyle reconstruction of the growing mandible in the adolescent patient.

    View details for DOI 10.1597/13-243

    View details for Web of Science ID 000352143500015

    View details for PubMedID 24625223

  • A mouse fetal skin model of scarless wound repair. Journal of visualized experiments : JoVE Walmsley, G. G., Hu, M. S., Hong, W. X., Maan, Z. N., Lorenz, H. P., Longaker, M. T. 2015: 52297-?


    Early in utero, but not in postnatal life, cutaneous wounds undergo regeneration and heal without formation of a scar. Scarless fetal wound healing occurs across species but is age dependent. The transition from a scarless to scarring phenotype occurs in the third trimester of pregnancy in humans and around embryonic day 18 (E18) in mice. However, this varies with the size of the wound with larger defects generating a scar at an earlier gestational age. The emergence of lineage tracing and other genetic tools in the mouse has opened promising new avenues for investigation of fetal scarless wound healing. However, given the inherently high rates of morbidity and premature uterine contraction associated with fetal surgery, investigations of fetal scarless wound healing in vivo require a precise and reproducible surgical model. Here we detail a reliable model of fetal scarless wound healing in the dorsum of E16.5 (scarless) and E18.5 (scarring) mouse embryos.

    View details for DOI 10.3791/52297

    View details for PubMedID 25650841

  • Stem Cell-Based Therapeutics to Improve Wound Healing. Plastic surgery international Hu, M. S., Leavitt, T., Malhotra, S., Duscher, D., Pollhammer, M. S., Walmsley, G. G., Maan, Z. N., Cheung, A. T., Schmidt, M., Huemer, G. M., Longaker, M. T., Lorenz, H. P. 2015; 2015: 383581-?


    Issues surrounding wound healing have garnered deep scientific interest as well as booming financial markets invested in novel wound therapies. Much progress has been made in the field, but it is unsurprising to find that recent successes reveal new challenges to be addressed. With regard to wound healing, large tissue deficits, recalcitrant wounds, and pathological scar formation remain but a few of our most pressing challenges. Stem cell-based therapies have been heralded as a promising means by which to surpass current limitations in wound management. The wide differentiation potential of stem cells allows for the possibility of restoring lost or damaged tissue, while their ability to immunomodulate the wound bed from afar suggests that their clinical applications need not be restricted to direct tissue formation. The clinical utility of stem cells has been demonstrated across dozens of clinical trials in chronic wound therapy, but there is hope that other aspects of wound care will inherit similar benefit. Scientific inquiry into stem cell-based wound therapy abounds in research labs around the world. While their clinical applications remain in their infancy, the heavy investment in their potential makes it a worthwhile subject to review for plastic surgeons, in terms of both their current and future applications.

    View details for DOI 10.1155/2015/383581

    View details for PubMedID 26649195

    View details for PubMedCentralID PMC4663003

  • A mouse fetal skin model of scarless wound repair. Journal of visualized experiments : JoVE Walmsley, G. G., Hu, M. S., Hong, W. X., Maan, Z. N., Lorenz, H. P., Longaker, M. T. 2015

    View details for DOI 10.3791/52297

    View details for PubMedID 25650841

  • Tissue engineering and regenerative repair in wound healing. Annals of biomedical engineering Hu, M. S., Maan, Z. N., Wu, J., Rennert, R. C., Hong, W. X., Lai, T. S., Cheung, A. T., Walmsley, G. G., Chung, M. T., McArdle, A., Longaker, M. T., Lorenz, H. P. 2014; 42 (7): 1494-1507


    Wound healing is a highly evolved defense mechanism against infection and further injury. It is a complex process involving multiple cell types and biological pathways. Mammalian adult cutaneous wound healing is mediated by a fibroproliferative response leading to scar formation. In contrast, early to mid-gestational fetal cutaneous wound healing is more akin to regeneration and occurs without scar formation. This early observation has led to extensive research seeking to unlock the mechanism underlying fetal scarless regenerative repair. Building upon recent advances in biomaterials and stem cell applications, tissue engineering approaches are working towards a recapitulation of this phenomenon. In this review, we describe the elements that distinguish fetal scarless and adult scarring wound healing, and discuss current trends in tissue engineering aimed at achieving scarless tissue regeneration.

    View details for DOI 10.1007/s10439-014-1010-z

    View details for PubMedID 24788648

  • Gene expression in fetal murine keratinocytes and fibroblasts JOURNAL OF SURGICAL RESEARCH Hu, M. S., Januszyk, M., Hong, W. X., Walmsley, G. G., Zielins, E. R., Atashroo, D. A., Maan, Z. N., McArdle, A., Takanishi, D. M., Gurtner, G. C., Longaker, M. T., Lorenz, H. P. 2014; 190 (1): 344-357


    Early fetuses heal wounds without the formation of a scar. Many studies have attempted to explain this remarkable phenomenon. However, the exact mechanism remains unknown. Herein, we examine the predominant cell types of the epidermis and dermis-the keratinocyte and fibroblast-during different stages of fetal development to better understand the changes that lead to scarring wound repair versus regeneration.Keratinocytes and fibroblasts were harvested and cultured from the dorsal skin of time-dated BALB/c fetuses. Total RNA was isolated and microarray analysis was performed using chips with 42,000 genes. Significance analysis of microarrays was used to select genes with >2-fold expression differences with a false discovery rate <2. Enrichment analysis was performed on significant genes to identify differentially expressed pathways.By comparing the gene expression profile of keratinocytes from E16 versus E18 fetuses, we identified 24 genes that were downregulated at E16. Analysis of E16 and E18 fibroblasts revealed 522 differentially expressed genes. Enrichment analysis showed the top 20 signaling pathways that were downregulated in E16 keratinocytes and upregulated or downregulated in E16 fibroblasts.Our data reveal 546 differentially expressed genes in keratinocytes and fibroblasts between the scarless and scarring transition. In addition, a total of 60 signaling pathways have been identified to be either upregulated or downregulated in these cell types. The genes and pathways recognized by our study may prove to be essential targets that may discriminate between fetal wound regeneration and adult wound repair.

    View details for DOI 10.1016/j.jss.2014.02.030

    View details for Web of Science ID 000338444700051

  • The Role of Hypoxia-Inducible Factor in Wound Healing. Advances in wound care Hong, W. X., Hu, M. S., Esquivel, M., Liang, G. Y., Rennert, R. C., McArdle, A., Paik, K. J., Duscher, D., Gurtner, G. C., Lorenz, H. P., Longaker, M. T. 2014; 3 (5): 390-399


    Significance: Poor wound healing remains a significant health issue for a large number of patients in the United States. The physiologic response to local wound hypoxia plays a critical role in determining the success of the normal healing process. Hypoxia-inducible factor-1 (HIF-1), as the master regulator of oxygen homeostasis, is an important determinant of healing outcomes. HIF-1 contributes to all stages of wound healing through its role in cell migration, cell survival under hypoxic conditions, cell division, growth factor release, and matrix synthesis throughout the healing process. Recent Advances: Positive regulators of HIF-1, such as prolyl-4-hydroxylase inhibitors, have been shown to be beneficial in enhancing diabetic ischemic wound closure and are currently undergoing clinical trials for treatment of several human-ischemia-based conditions. Critical Issues: HIF-1 deficiency and subsequent failure to respond to hypoxic stimuli leads to chronic hypoxia, which has been shown to contribute to the formation of nonhealing ulcers. In contrast, overexpression of HIF-1 has been implicated in fibrotic disease through its role in increasing myofibroblast differentiation leading to excessive matrix production and deposition. Both positive and negative regulators of HIF-1 therefore provide important therapeutic targets that can be used to manipulate HIF-1 expression where an excess or deficiency in HIF-1 is known to correlate with pathogenesis. Future Directions: Targeting HIF-1 during wound healing has many important clinical implications for tissue repair. Counteracting the detrimental effects of excessive or deficient HIF-1 signaling by modulating HIF-1 expression may improve future management of poorly healing wounds.

    View details for PubMedID 24804159

  • The Role of Stem Cells During Scarless Skin Wound Healing. Advances in wound care Hu, M. S., Rennert, R. C., McArdle, A., Chung, M. T., Walmsley, G. G., Longaker, M. T., Lorenz, H. P. 2014; 3 (4): 304-314


    Significance: In early gestation, fetal skin wounds undergo regeneration and healing without a scar. This phenomenon is intrinsic to early fetal skin but disappears during late gestation. Adult wounds undergo repair via a fibroproliferative response that leads to incomplete regeneration of the original tissue and a resultant scar. This outcome can have devastating effects for patients and is a significant financial burden to the healthcare system. Recent Advances: Studies have demonstrated the possible role of several stem cells in wound healing. In particular, epidermal stem cells and mesenchymal stem cells have been implicated in wound repair and regeneration. Recently, stem cells with adult epidermal stem cell markers have been found in fetal skin dermis. These cells are thought to play a role in scarless fetal wound healing. Critical Issues: Despite numerous studies on scarless fetal wound healing, the exact mechanism is still largely unknown. Although inflammation is greatly reduced, the stem cell profile of regenerating fetal skin wounds remains unknown. Without a detailed understanding of stem cell differences between fetal and adult wounds, the ability to prevent or treat both normal and pathologic excessive scarring, in the form of keloids and hypertrophic scars, is limited. Future Directions: Further studies on differences between fetal and adult skin-specific stem cells may elucidate the mechanism of scarless wound healing in the early fetus. With this knowledge, the potential to reduce scarring in adult wounds may be achieved.

    View details for PubMedID 24761362

  • Abstract 140: identification, characterization, and prospective isolation of a fibroblast lineage contributing to dermal development, cutaneous scarring, radiation fibrosis, and cancer stroma. Plastic and reconstructive surgery Walmsley, G. G., Rinkevich, Y., Hu, M. S., McArdle, A., Maan, Z. N., Lorenz, H. P., Weissman, I. L., Longaker, M. T. 2014; 133 (3): 157-?

    View details for DOI 10.1097/01.prs.0000444968.20280.4d

    View details for PubMedID 25942251

  • Abstract 135: improved engraftment of autologous skin grafts in diabetic mice with adipose-derived stem cells. Plastic and reconstructive surgery Hu, M., Hong, W. X., Senarath-Yapa, K., Zimmermann, A., Chung, M., Esquivel, M., McArdle, A., Walmsley, G., Maan, Z., Garza, R., Lorenz, H. P., Longaker, M. 2014; 133 (3): 151-?

    View details for DOI 10.1097/01.prs.0000444962.89785.8e

    View details for PubMedID 25942246

  • Gene expression in fetal murine keratinocytes and fibroblasts. The Journal of surgical research Hu, M. S., Januszyk, M., Hong, W. X., Walmsley, G. G., Zielins, E. R., Atashroo, D. A., Maan, Z. N., McArdle, A., Takanishi, D. M., Gurtner, G. C., Longaker, M. T., Lorenz, H. P. 2014


    Early fetuses heal wounds without the formation of a scar. Many studies have attempted to explain this remarkable phenomenon. However, the exact mechanism remains unknown. Herein, we examine the predominant cell types of the epidermis and dermis-the keratinocyte and fibroblast-during different stages of fetal development to better understand the changes that lead to scarring wound repair versus regeneration.Keratinocytes and fibroblasts were harvested and cultured from the dorsal skin of time-dated BALB/c fetuses. Total RNA was isolated and microarray analysis was performed using chips with 42,000 genes. Significance analysis of microarrays was used to select genes with >2-fold expression differences with a false discovery rate <2. Enrichment analysis was performed on significant genes to identify differentially expressed pathways.By comparing the gene expression profile of keratinocytes from E16 versus E18 fetuses, we identified 24 genes that were downregulated at E16. Analysis of E16 and E18 fibroblasts revealed 522 differentially expressed genes. Enrichment analysis showed the top 20 signaling pathways that were downregulated in E16 keratinocytes and upregulated or downregulated in E16 fibroblasts.Our data reveal 546 differentially expressed genes in keratinocytes and fibroblasts between the scarless and scarring transition. In addition, a total of 60 signaling pathways have been identified to be either upregulated or downregulated in these cell types. The genes and pathways recognized by our study may prove to be essential targets that may discriminate between fetal wound regeneration and adult wound repair.

    View details for DOI 10.1016/j.jss.2014.02.030

    View details for PubMedID 24726057

  • Using bioabsorbable fixation systems in the treatment of pediatric skull deformities leads to good outcomes and low morbidity CHILDS NERVOUS SYSTEM Gephart, M. G., Woodard, J. I., Arrigo, R. T., Lorenz, H. P., Schendel, S. A., Edwards, M. S., Guzman, R. 2013; 29 (2): 297-301


    Bioabsorbable fixation systems have been widely employed in pediatric patients for cranial reconstruction, obviating the complications of hardware migration and imaging artifact occurring with metallic implants. Recent concern over complications unique to bioabsorbable materials, such as inflammatory reaction and incomplete resorption, necessitates additional conclusive studies to further validate their use in pediatric neurosurgery and craniofacial surgery. Likewise, long-term follow-up in this clinical cohort has not previously been described.We included consecutive pediatric patients under the age of 2, from Lucile Packard Children's Hospital, who underwent cranial vault reconstruction with the use of a bioabsorbable fixation system between 2003 and 2010. Hospital records were queried for patient characteristics, intraoperative data, and postoperative complications.Ninety-five patients with the following preoperative pathologies were analyzed: craniosynostosis (87), cloverleaf skull (5), frontonasal dysplasia (1), and frontonasal encephalocele (2). Median age was 6 months (range 1-24 months). Average case duration was 204 minutes (range 40-392 min), with median of 154 mL blood loss (range 30-500 mL). Ninety-three percent of patients had 1-4 plates implanted with 48% receiving three plates. The median number of screws used was 59 (range 0-130). The median length of hospital stay was 4 days (range 2-127 days) with an average follow-up of 22 months (five postoperative visits). The complications related to hardware implantation included swelling (1%) and broken hardware (1%), the latter of which required reoperation.The bioabsorbable fixation systems for cranial vault reconstruction in children less than 2 years of age is safe with tolerable morbidity rates.

    View details for DOI 10.1007/s00381-012-1938-y

    View details for PubMedID 23099613

  • Scarless fetal skin wound healing update BIRTH DEFECTS RESEARCH PART C-EMBRYO TODAY-REVIEWS Lo, D. D., Zimmermann, A. S., Nauta, A., Longaker, M. T., Lorenz, H. P. 2012; 96 (3): 237-247


    Scar formation, a physiologic process in adult wound healing, can have devastating effects for patients; a multitude of pathologic outcomes, affecting all organ systems, stems from an amplification of this process. In contrast to adult wound repair, the early-gestation fetal skin wound heals without scar formation, a phenomenon that appears to be intrinsic to fetal skin. An intensive research effort has focused on unraveling the mechanisms that underlie scarless fetal wound healing in an attempt to improve the quality of healing in both children and adults. Unique properties of fetal cells, extracellular matrix, cytokine profile, and gene expression contribute to this scarless repair. Despite the great increase in knowledge gained over the past decades, the precise mechanisms regulating scarless fetal healing remain unknown. Herein, we describe the current proposed mechanisms underlying fetal scarless wound healing in an effort to recapitulate the fetal phenotype in the postnatal environment.

    View details for DOI 10.1002/bdrc.21018

    View details for Web of Science ID 000310475000003

    View details for PubMedID 23109319

  • Abdominal wall reconstruction with dual layer cross-linked porcine dermal xenograft: The "Pork Sandwich" herniorraphy JOURNAL OF PLASTIC RECONSTRUCTIVE AND AESTHETIC SURGERY Satterwhite, T. S., Miri, S., Chung, C., Spain, D. A., Lorenz, H. P., Lee, G. K. 2012; 65 (3): 333-341


    The repair of large ventral hernias is a challenging problem. This study investigated the use of decellularized, chemically cross-linked porcine dermal xenograft in conjunction with component separation (a.k.a. the "Pork Sandwich" Herniorraphy) in the repair of abdominal wall defects.We prospectively collected data over a 3-year period. Primary or near-total primary fascial closure was our goal in operative repair. A cross-linked porcine dermal xenograft mesh underlay and overlay were used to provide maximal reinforcement of the repair. Outcomes were compared with a case-controlled cohort of 84 patients who underwent ventral hernia repairs with alternative methods at our institution.Nineteen patients were included. Mean age was 55 years old, and mean body mass index (BMI) was 30 kg/m(2). Mean defect size was 321 cm(2). Post-operative complications were observed in ten out of 19 patients. Complications included seroma (n = 2), wound infection (n = 2), abscess (n = 1), skin necrosis (n = 6), and fistula formation (n = 3). Seven patients required re-operation. Statistically significant factors (p < 0.05) that contributed to increased post-operative complications or re-operation rates included smoking, presence of pre-operative enterocutaneous fistulae, extended post-operative hospital stay (>2 weeks), and a defect size greater than 300 cm(2). There were no hernia recurrences in our "Pork Sandwich" group, which contrasted favorably to the retrospective case-control group in which the hernia recurrence rate was 19% (p = 0.038).For the repair of abdominal hernias, primary closure, with component separation as needed, with an underlay and overlay of cross-liked porcine xenograft should be considered to minimize risk of recurrent herniation. Additional long-term prospective comparative studies are needed for further validation of the optimal method and material for repair.

    View details for DOI 10.1016/j.bjps.2011.09.044

    View details for Web of Science ID 000300524800016

    View details for PubMedID 22000333

  • Congenital Microcystic Adnexal Carcinoma ARCHIVES OF DERMATOLOGY Fu, T., Clark, F. L., Lorenz, H. P., Bruckner, A. L. 2011; 147 (2): 256-257

    View details for Web of Science ID 000287536500029

    View details for PubMedID 21339467

  • Initial Clinical Experience Using a Novel Ultraportable Negative Pressure Wound Therapy Device WOUNDS-A COMPENDIUM OF CLINICAL RESEARCH AND PRACTICE Fong, K. D., Hu, D., Eichstadt, S. L., Gorell, E., Munoz, C. A., Lorenz, H. P., Chang, A. L. 2010; 22 (9): 230-236


     Background. Traditional negative pressure wound therapy (NPWT) devices, such as the electrically powered V.A.C.® Therapy System (KCI, San Antonio, TX), are important tools in the treatment of both acute and chronic wounds. The following describes the first clinical experience using a novel, non-electrically powered, ultraportable NPWT device called the Smart Negative Pressure (SNaP™) Wound Care System (Spiracur, Sunnyvale, CA).Twelve consecutive adult subjects with chronic wounds ranging from neuropathic wounds to venous stasis ulcers were treated with the SNaP System at an academic outpatient dermatology clinic. Subjects were followed biweekly for complications and wound healing progression over a 4-week period.Of the 12 subjects treated, 5 achieved complete wound healing within 4 weeks. All subjects demonstrated healing after treatment with the SNaP System, and statistically significant healing was reached at 4 weeks (P < 0.01) for patients who were able to complete the treatment protocol. Use of the SNaP System promoted cleaner wound beds with robust granulation tissue formation. There were no serious adverse events directly related to the device. The most common complaint was mild or moderate wound pain in 3 of 12 subjects.These findings support the safety and potential clinical utility of a new ultraportable NPWT device for the treatment of chronic wounds.  .

    View details for Web of Science ID 000285531700007

  • The SNaP System: Biomechanical and Animal Model Testing of a Novel Ultraportable Negative-Pressure Wound Therapy System PLASTIC AND RECONSTRUCTIVE SURGERY Fong, K. D., Hu, D., Eichstadt, S., Gupta, D. M., Pinto, M., Gurtner, G. C., Longaker, M. T., Lorenz, H. P. 2010; 125 (5): 1362-1371


    Negative-pressure wound therapy is traditionally achieved by attaching an electrically powered pump to a sealed wound bed and applying subatmospheric pressure by means of gauze or foam. The Smart Negative Pressure (SNaP) System (Spiracur, Inc., Sunnyvale, Calif.) is a novel ultraportable negative-pressure wound therapy system that does not require an electrically powered pump.Negative pressure produced by the SNaP System, and a powered pump, the wound vacuum-assisted closure advanced-therapy system (Kinetic Concepts, Inc., San Antonio, Texas), were compared in vitro using bench-top pressure sensor testing and microstrain and stress testing with pressure-sensitive film and micro-computed tomographic scan analysis. In addition, to test in vivo efficacy, 10 rats underwent miniaturized SNaP (mSNaP) device placement on open wounds. Subject rats were randomized to a system activation group (approximately -125 mmHg) or a control group (atmospheric pressure). Wound measurements and histologic data were collected for analysis.Bench measurement revealed nearly identical negative-pressure delivery and mechanical strain deformation patterns between both systems. Wounds treated with the mSNaP System healed faster, with decreased wound size by postoperative day 7 (51 percent versus 12 percent reduction; p < 0.05) and had more rapid complete reepithelialization (21 days versus 32 days; p < 0.05). The mSNaP device also induced robust granulation tissue formation.The SNaP System and an existing electrically powered negative-pressure wound therapy system have similar biomechanical properties and functional wound-healing benefits. The potential clinical efficacy of the SNaP device for the treatment of wounds is supported.

    View details for DOI 10.1097/PRS.0b013e3181d62b25

    View details for Web of Science ID 000276886600008

    View details for PubMedID 20440156

  • Germ plasm-like Dot cells maintain their wound regenerative function after in vitro expansion CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY Kong, W., Li, S., Lorenz, H. P. 2010; 37 (4): e136-e144


    1. Wounds in fetal skin heal without scarring; however, the mechanism for this is unknown. We have identified a novel group of protein and nucleotides-positive particles in fetal and adult mouse blood and in human blood, and termed them 'Dot cells'. Freshly isolated Dot cells regenerate wounds with less scarring and can be cultured without feeder layers. 2. Because the morphology of Dot cells has never been described, in the present study we describe the specific characterizations of Dot cells, including their growth pattern in vitro, and their expressions of stem cell markers using fluorescent cell sorting analyses and immunofluorescent histology. Our data indicates that cultured Dot cells express stem cell surface markers and embryonic stem cell transcription markers, such as Oct4, Nanog and Sox-2. In addition, Dot cells express VASA, the germ plasm specific marker. 3. To confirm whether Dot cells maintain their wound regenerative activity after in vitro expansion, in vitro cultured Dot cells were transplanted to wounded mice. Dot cells from albino mice maintain their wound regenerative activities after intravenous transplantation to black-background diabetic mice. In addition, Dot cells regenerate both the epithelial and dermal cells in the wounds of wild-type mice. The regenerated hair follicles, smooth muscle and dermal tissues express transiently to VASA. 4. Our data demonstrate that Dot cells are newly identified organisms located in the blood and bone marrow of mammals. They express germ cell, embryonic stem cell and adult stem cell markers. Dot cells maintain their regenerative function after in vitro expansion.

    View details for DOI 10.1111/j.1440-1681.2010.05343.x

    View details for Web of Science ID 000275766900001

    View details for PubMedID 20409081

  • Cyclophilin C-Associated Protein/Mac-2 Binding Protein Colocalizes With Calnexin and Regulates the Expression of Tissue Transglutaminase JOURNAL OF CELLULAR PHYSIOLOGY Kong, W., Lin, B. W., Li, S., Longaker, M. T., Lorenz, H. P. 2010; 223 (1): 151-157


    Cyclophilin C-associated protein (CyCAP) or Mac-2 binding protein has been identified as a binding protein for cyclophilin C in mice and for Mac-2 (galectin-3) in human, suggesting its multiple binding activity to proteins. In the present study, using specific anti-rat-CyCAP antibody, we found that CyCAP colocalizes with calnexin at the location near the nuclear envelope, however CyCAP does not have colocalization with calreticulin. In senescent fibroblasts and interferon-gamma (IFNgamma) treated fibroblasts, both calnexin and CyCAP form larger polymers and are released from the endoplasmic reticulum (ER) through the cellular membrane to the extracellular area. Immunoprecipitation studies further confirm that the release of calnexin is through binding to CyCAP. Further, we found that tissue transglutaminase (tTG) protein is decreased, however not at the RNA level, in CyCAP null fibroblasts, which suggests that CyCAP is involved in tTG post-translational modification. Our data give novel evidence that CyCAP regulates the post-translational modification of tTG through its colocalization with calnexin in ER.

    View details for DOI 10.1002/jcp.22020

    View details for Web of Science ID 000275589300017

    View details for PubMedID 20049854

  • Upregulation of Neurodevelopmental Genes During Scarless Healing ANNALS OF PLASTIC SURGERY Antony, A. K., Kong, W., Lorenz, H. P. 2010; 64 (2): 247-250


    Scarless fetal skin wound healing is a paradigm for ideal skin repair and is dependent on peripheral nerve function.To further explore neurogenic mechanisms influence on the scarless skin repair, fetal rats were wounded on gestational days 16 (E16; n = 24) and 18 (E18; n = 8) and wounds were harvested at 1 and 3 days after injury. Unwounded skin at identical gestational age was used for control comparison. The scarless E16 and scarring E18 wounds underwent macroarray gene expression analysis (1172 genes).During the scarless healing period, 53 (4.5%) genes had a statistically significant upregulation post-injury with at least a 2- to 3-fold change 1 day after wounding and 14 (1.2%) genes 3 days after wounding (P < 0.05). Many neurodevelopmental genes were increased during scarless repair on post-injury days 1 and 3. Neuropeptide Y Receptor type I, cJun related Transcription Factor (junD), Synaptophysin, SNAP 25, Neuronal calcium sensor 1 (NCS1), neural visine-like calcium binding protein 1 (NVP1), nerve growth factor-induced gene A (NGFI-A/EGR1), VGF8A protein, p27kip1, and members of the GABA and serotonin family each had 2- to 3-fold expression increases (P < 0.05).We speculate that fetal skin cells express neurotrophins during skin development that regulate peripheral neuron formation. During injury these factors promote the survival and regeneration of peripheral neurons; this interaction of neuropeptides, neuropeptide receptors, and neurotrophins may modulate the fetal scarless repair mechanisms in response to injury. Identification of these neurodevelopmental candidate genes provides insight for new investigation into mechanisms regulating scarless healing.

    View details for DOI 10.1097/SAP.0b013e3181a20af8

    View details for Web of Science ID 000274001600027

    View details for PubMedID 20098115

  • Interaction of Wingless Protein (Wnt), Transforming Growth Factor-beta 1, and Hyaluronan Production in Fetal and Postnatal Fibroblasts PLASTIC AND RECONSTRUCTIVE SURGERY Carre, A. L., James, A. W., Macleod, L., Kong, W., Kawai, K., Longaker, M. T., Lorenz, H. P. 2010; 125 (1): 74-88


    Mammalian fetal skin injury heals scarlessly. The intrinsic differences between embryonic and adult fibroblasts that underlie this observation are poorly understood. Several studies have linked Wnt proteins with skin morphogenesis. The authors' study aimed to establish a correlation between beta-catenin-dependent (canonical) Wnt protein, transforming growth factor (TGF)-beta1, and the expression of hyaluronan synthesis enzymes during scarless versus scarring wound healing.Wnt signaling was quantified after 1.5-mm skin wounds were created in BAT-gal fetal (e16.5) and postnatal (p1) mice. Canonical Wnt signals were localized by X-gal staining and quantified with quantitative real-time polymerase chain reaction. Primary embryonic and postnatal mouse dermal fibroblasts were treated with recombinant Wnt3a or TGF-beta1. Proliferation was assayed by bromodeoxyuridine incorporation. Gene expression of enzymes that regulate hyaluronan production and turnover was examined by quantitative real-time polymerase chain reaction (hyaluronan synthases or HAS1-3, hyaluronadase-2), as well as other target genes for Wnt and TGF-beta (Axin2, TGF-beta1, TGF-beta3, type 1 collagen, proliferating cell nuclear antigen).Canonical Wnt signaling increased following wounding in postnatal, but not fetal, mice. In vitro, rmWnt3a increased postnatal fibroblast proliferation but not in embryonic cells. Both Wnt3a and TGF-beta1 induced HAS2 and HAS3 gene expression in embryonic fibroblasts, while HAS1 and Hyal2 were induced in postnatal fibroblasts. Finally, rmWnt3a significantly increased type I collagen expression, particularly in postnatal fibroblasts, and influenced expression of TGF-beta isoforms.Increased canonical Wnt signaling occurs during postnatal but not fetal cutaneous wound repair. Fetal and postnatal fibroblasts have a disparate response to rmWnt3a in vitro. rmWnt3a affects postnatal fibroblasts in a similar fashion to rhTGF-beta1, a known profibrotic cytokine.

    View details for DOI 10.1097/PRS.0b013e3181c495d1

    View details for Web of Science ID 000273417000011

    View details for PubMedID 20048602

  • A rare case of mistaken identity: metastatic hepatocellular carcinoma to the nose. Journal of surgical case reports Lee, G., Lorenz, H., Mohan, S. 2010; 2010 (4): 3-?


    Hepatocellular carcinoma most often metastasizes to the lungs, abdominal lymph nodes, or bone. The identification of extrahepatic metastases of hepatocellular carcinoma to the sinonasal region has rarely been reported. We report a case of a 49 year-old man with a history of stage IV hepatocellular carcinoma presenting with two adjacent pigmented lesions on the tip of his nose. Initial pathological staining identified the lesion as a primary melanoma. However, upon further examination with the chemical markers CEA, CAM 5.2, and Keratin, it was determined that the lesions were consistent with hepatocellular carcinoma. This case highlights a potentially rare situation of mistaking a liver metastasis for a malignant melanoma.

    View details for DOI 10.1093/jscr/2010.4.3

    View details for PubMedID 24946306

  • High expression of collagen XV and nonfibrillar elastic fibers in embryonic as compared with postnatal skin 95th Annual Clinical Congress of the American-College-of-Surgeons/64th Annual Sessions of the Owen H Wangensteen Forum on Fundamental Surgical Problems Carre, A. L., James, A., Macleod, L., Kawai, K., Longaker, M. T., Lorenz, H. P. ELSEVIER SCIENCE INC. 2009: S71–S71
  • FETAL SKIN WOUND HEALING ADVANCES IN CLINICAL CHEMISTRY VOL 48 Buchanan, E. P., Longaker, M. T., Lorenz, H. P. 2009; 48: 137-161


    The developing fetus has the ability to heal wounds by regenerating normal epidermis and dermis with restoration of the extracellular matrix (ECM) architecture, strength, and function. In contrast, adult wounds heal with fibrosis and scar. Scar tissue remains weaker than normal skin with an altered ECM composition. Despite extensive investigation, the mechanism of fetal wound healing remains largely unknown. We do know that early in gestation, fetal skin is developing at a rapid pace and the ECM is a loose network facilitating cellular migration. Wounding in this unique environment triggers a complex cascade of tightly controlled events culminating in a scarless wound phenotype of fine reticular collagen and abundant hyaluronic acid. Comparison between postnatal and fetal wound healing has revealed differences in inflammatory response, cellular mediators, cytokines, growth factors, and ECM modulators. Investigation into cell signaling pathways and transcription factors has demonstrated differences in secondary messenger phosphorylation patterns and homeobox gene expression. Further research may reveal novel genes essential to scarless repair that can be manipulated in the adult wound and thus ameliorate scar.

    View details for DOI 10.1016/S0065-2423(09)48006-5

    View details for Web of Science ID 000270339800006

    View details for PubMedID 19803418

  • Wingless protein (Wnt) expression in fetal wounds 94th Annual Clinical Congress of the American-College-of-Surgeons/63rd Annual Sessions of the Owen H Wangensteen Forum on Fundamental Surgical Problems Carre, A. L., Joseph, K., Chang, E., Longaker, M. T., Helms, J., Lorenz, H. P. ELSEVIER SCIENCE INC. 2008: S60–S61
  • Blood-derived small Dot cells reduce scar in wound healing EXPERIMENTAL CELL RESEARCH Kong, W., Li, S., Longaker, M. T., Lorenz, H. P. 2008; 314 (7): 1529-1539


    Wounds in fetal skin heal without scar, however the mechanism is unknown. We identified a novel group of E-cadherin positive cells in the blood of fetal and adult mice and named them "Dot cells". The percentage of Dot cells in E16.5 fetal mice blood is more than twenty times higher compared to adult blood. Dot cells also express integrin beta1, CD184, CD34, CD13low and Sca1low, but not CD45, CD44, and CD117. Dot cells have a tiny dot shape between 1 and 7 microm diameters with fast proliferation in vitro. Most of the Dot cells remain positive for E-cadherin and integrin beta1 after one month in culture. Transplantation of Dot cells to adult mice heals skin wounds with less scar due to reduced smooth muscle actin and collagen expression in the repair tissue. Tracking GFP-positive Dot cells demonstrates that Dot cells migrate to wounds and differentiate into dermal cells, which also express strongly to FGF-2, and later lose their GFP expression. Our results indicate that Dot cells are a group of previously unidentified cells that have strong wound healing effect. The mechanism of scarless wound healing in fetal skin is due to the presence of a large number of Dot cells.

    View details for DOI 10.1016/j.yexcr.2008.01.022

    View details for Web of Science ID 000254798600010

    View details for PubMedID 18295204

    View details for PubMedCentralID PMC2692606

  • Adult and fetal wound healing FRONTIERS IN BIOSCIENCE-LANDMARK Hantash, B. M., Zhao, L., Knowles, J. A., Lorenz, H. P. 2008; 13: 51-61


    Mammalian wound healing is an intricate process involving the coordinated interaction of a variety of tissue types and cellular lineages. This is governed by a complex array of physical, biological and chemical signals. In adult tissue, the successful completion of wound healing inevitably results in the formation of scar. However, animal studies of embryonic tissue have shown that early gestation fetal wounds heal with complete restoration of tissue structure and function. The exact mechanisms underlying scarless healing in the fetus remain to be elucidated.

    View details for DOI 10.2741/2559

    View details for Web of Science ID 000255775700003

    View details for PubMedID 17981527

  • Infant mandibular distraction with an internal curvilinear device JOURNAL OF CRANIOFACIAL SURGERY Miller, J. J., Kahn, D., Lorenz, H. P., Schendel, S. A. 2007; 18 (6): 1403-1407


    Mandibular distraction has proven to be a valuable tool for lengthening the hypoplastic mandible and relieving airway obstruction in infants. Numerous devices have been developed to achieve the desired mandibular lengthening. Complications including poor vector control, need to mold regenerate, facial scarring, external pin loosening, and bulky hardware have been associated with previous devices. In an attempt to circumvent some of these problems, the senior author developed an internal curvilinear device (Osteomed Corporation, Dallas, TX), which is applicable to the infant mandible. The aim of this paper is to describe the use of this distractor as well as its indications and outcomes.Twelve micrognathic infants (ages range from 9 days to 8 months) who underwent mandibular distraction between March 2005-May 2006 at Lucile Packard Children's Hospital were included in the study. Preoperative workup included an evaluation by a multidisciplinary team including a pediatric otolaryngologist, neonatal intensivist, pediatric pulmonologist, occupational therapist, and craniofacial surgeon. Pre and postoperative maxillomandibular discrepancy, sleep study, feeding evaluation, and three-dimensional computerized tomography scans were compared. All patients tolerated the distraction process well to completion without postoperative complication, except for one patient who had temporary facial nerve weakness, which resolved in 2 months. All patients with obstructive apnea had the obstructive component improved. The last six patients had pre and postoperative polysomnograms to document the improvement. Two patients with neurologic impairment had persistent central apnea. One nonsyndromic patient with inability to feed and feeding-related airway obstruction was taking complete oral feeds 2 weeks after distraction.Mandibular distraction with an internal curvilinear device is effective at relieving airway obstruction in micrognathic infants, while avoiding some previously reported complications.

    View details for Web of Science ID 000251517500026

    View details for PubMedID 17993889

  • Keratinocytes modulate fetal and postnatal fibroblast transforming growth factor-beta and Smad expression in co-culture PLASTIC AND RECONSTRUCTIVE SURGERY Colwell, A. S., Yun, R., Krummel, T. M., Longaker, M. T., Lorenz, H. P. 2007; 119 (5): 1440-1445


    The mechanism of fetal scarless wound repair is poorly understood but is thought to involve unique characteristics and behavior patterns of the fetal dermal fibroblast. The authors hypothesized that keratinocytes may differentially modulate expression of key growth factors expressed during wound healing in fetal and postnatal fibroblasts.Murine E17 fetal (n = 12 animals) and newborn (n = 8 animals) fibroblasts were grown in isolation and co-culture with newborn keratinocytes (n = 12 animals). Quantitative real-time polymerase chain reaction was performed for transforming growth factor (TGF)-beta isoform, receptor, and signaling molecule (Smad) gene expression in each group under both conditions.At baseline, fetal fibroblasts have 1.8-fold greater TGF-beta3 expression than postnatal fibroblasts (p < 0.01). Keratinocytes induce a further increase of TGF-beta3 expression (p < 0.01) but decreased TGF-beta1, TGF-beta2, TGF-beta receptor (R)-I, and TGF-betaR-II expression in fetal fibroblasts. Keratinocytes also induce an increase in TGF-beta3 (p < 0.01) and a decrease TGF-beta2, TGF-betaR-I, and TGF-betaR-II expression in postnatal fibroblasts; however, TGF-beta1 expression is unchanged. Fetal fibroblasts have lower baseline expression of Smad3 and Smad4 than postnatal fibroblasts (p < 0.05). Keratinocytes decrease Smad3 and increase Smad7 expression in both fetal and postnatal fibroblasts (p < 0.01). In contrast, keratinocytes decrease Smad2 only in fetal fibroblasts (p < 0.05).Keratinocytes have an overall antifibrotic influence on both fetal and postnatal fibroblasts in co-culture conditions. These data further characterize intrinsic differences between fetal and postnatal fibroblasts.

    View details for DOI 10.1097/01.prs.0000256049.53562.39

    View details for Web of Science ID 000245711700007

    View details for PubMedID 17415238

  • Untitled - Reply JOURNAL OF PEDIATRIC SURGERY Dutta, S., Lorenz, H. P., Albanese, C. T. 2007; 42 (4): 752-752
  • Re: Differential effects of FGFR2 mutation in ophthalniologic findings in Apert syndrome. Discussion JOURNAL OF CRANIOFACIAL SURGERY Kwan, M. D., Wan, D. C., Lorenz, H. P., Longaker, M. T. 2007; 18 (2): 459-460

    View details for Web of Science ID 000245424400039

    View details for PubMedID 17414305

  • Transforming growth factor-beta, smad, and collagen expression patterns in fetal and adult keratinocytes PLASTIC AND RECONSTRUCTIVE SURGERY Colwell, A. S., Faudoa, R., Krummel, T. M., Longaker, M. T., Lorenz, H. P. 2007; 119 (3): 852-857


    The transforming growth factor (TGF)-beta family regulates cellular proliferation, differentiation, and migration. To better define the influence of keratinocyte-derived TGF-beta during development and repair, the authors examined the TGF-beta isoform, receptor, signal messenger Smad, and collagen type I expression in fetal and postnatal keratinocytes.Sprague-Dawley rat keratinocytes were isolated in primary culture from fetal E17 (n = 6), newborn (n = 4), and 6-week-old adults (n = 4). Under serum-free conditions, quantitative polymerase chain reaction was performed for TGF-beta1, TGF-beta2, and TGF-beta3 ligands; TGF-beta receptor 1 (RI) and TGF-beta receptor 2 (RII); Smad4 and Smad7; and collagen type I expression.Total TGF-beta isoform expression increased 1.7-fold from E17 to newborn (p < 0.05) and adult (p < 0.01) ages. TGF-beta1 expression was 25-fold greater than TGF-beta2 and 10-fold greater than TGF-beta3 in fetal keratinocytes (p < 0.01 for each). The expression of TGF-beta1 was fivefold greater compared with TGF-beta2 and TGF-beta3 in newborn and adult keratinocytes (p < 0.01). TGF-beta-RI expression increased more than twofold (p < 0.01), whereas TGF-beta-RII expression increased by 25 percent (p < 0.01) from E17 to adult age. Smad4 increased more than twofold (p < 0.01), whereas Smad7 did not change appreciably. Collagen type I expression increased over 100-fold from E17 to adult (p < 0.005).The TGF-beta system and collagen type I have increased expression with increasing gestational age in keratinocytes. This suggests an increased profibrotic TGF-beta response and collagen type I production in keratinocytes during skin differentiation at ages associated with scarring.

    View details for DOI 10.1097/01.prs.0000255541.39993.66

    View details for Web of Science ID 000244438700011

    View details for PubMedID 17312487

  • Cyclophilin C-associated protein is up-regulated during wound healing JOURNAL OF CELLULAR PHYSIOLOGY Kong, W., Li, S., Longaker, M. T., Lorenz, H. P. 2007; 210 (1): 153-160


    Cyclophilin C-associated protein (CyCAP) is identified from macrophages. It locates in intracellular, membrane bound and extracellular, suggesting it has an important role, however both of its regulation and function have not been elucidated. The expression of CyCAP in skin and during wound healing is also unknown. We demonstrate that CyCAP is expressed in both dermal fibroblasts and keratinocytes. In the dermis, the majority of CyCAP protein is located intracellular in a filamentous protein form while a lesser amount is in the extracellular matrix (ECM). CyCAP gene and protein expression is increased 1 day after skin wound healing in both fetal and adult rats and remains elevated level up to 1 week in adult rats. Immunohistochemistry studies demonstrate that the increased CyCAP expression locates mainly to inflammatory cells, including macrophages, monocytes and lymphocytes during wound healing. Interferon-gamma increases CyCAP gene and protein expression in cultured rat fibroblasts. We also found that wound healing is slower and less collagen is expressed in skin of CyCAP null mice. These data are the first observations of CyCAP expression in skin and during wound repair. Our data indicates that CyCAP is regulated by IFNgamma and may function on immune defense in macrophages, lymphocytes, dermal fibroblasts and keratinocytes during wound healing.

    View details for DOI 10.1002/jcp.20830

    View details for Web of Science ID 000242568200016

    View details for PubMedID 16998803

  • Influence of the fetal keratinocyte in scarless repair 12th Biennial Meeting of the International-Society-Craniofacial-Surgery Antony, A. K., Kong, W., Longaker, M. T., Lorenz, H. P. MEDIMOND S R L. 2007: 33–36
  • Retinoic acid induces differential expression of MMP-1 and 9 in fetal and adult fibroblasts 12th Biennial Meeting of the International-Society-Craniofacial-Surgery Antony, A. K., Bari, S., Kong, W., Longaker, M. T., Lorenz, H. P. MEDIMOND S R L. 2007: 29–31
  • Upregulation of neurodevelopmental genes during scarless healing 12th Biennial Meeting of the International-Society-Craniofacial-Surgery Antony, A. K., Kong, W. Y., Longaker, M. T., Lorenz, H. P. MEDIMOND S R L. 2007: 25–27
  • Wnt signaling pathway critical for fetal wound healing 12th Biennial Meeting of the International-Society-Craniofacial-Surgery Knowles, J. A., Hantash, B. M., Longaker, M. T., Lorenz, H. P. MEDIMOND S R L. 2007: 69–72
  • Epithelial-mesenchymal transition occurs after epidermal development in mouse skin EXPERIMENTAL CELL RESEARCH Kong, W., Li, S., Liu, C., Bari, A. S., Longaker, M. T., Lorenz, H. P. 2006; 312 (19): 3959-3968


    In the present study, we studied epithelial-mesenchymal transition (EMT) with fetal and postnatal serial skin sections. E-cadherin, occludin and zonula occludens 1 (ZO-1)-expressing cells appear in the dermal area from E18.5 to postnatal day 9 (P9), with highest expression from P2 to P5. The co-expression of mesenchymal marker alpha-smooth muscle (alpha-SMA), fibronectin and vimentin with E-cadherin in these dermal cells was further examined. Almost no dermal cells express alpha-SMA before P0. From P2 to P6, cells expressing both E-cadherin and alpha-SMA appear in the dermis. In contrast, fibronectin-releasing cells were detected in the dermis as early as on E15.5, although on P5, some dermal cells was found weakly expressing both fibronectin and E-cadherin, most cells strongly expressing fibronectin did not express E-cadherin. Vimentin was mainly expressed in both endothelial and blood-derived cells and did not show co-expression with E-cadherin. Confocal microscopy studies further found that during EMT, E-cadherin appears intracellularly, while the expression of alpha-SMA starts from the membrane area and moves to the cytosol of the cells. Our data are the first in vivo evidence that EMT occurs during mouse skin development. Dermal cells are derived from EMT and other origins, including blood, during skin development.

    View details for DOI 10.1016/j.yexcr.2006.08.029

    View details for Web of Science ID 000241790000023

    View details for PubMedID 17027753

  • Endoscopic excision of benign forehead masses: a novel approach for pediatric general surgeons JOURNAL OF PEDIATRIC SURGERY Dutta, S., Lorenz, H. P., Albanese, C. T. 2006; 41 (11): 1874-1878


    Benign tumors of the brow and forehead are commonly managed by pediatric general surgeons by excision through an overlying incision. Cosmetic results in children can be suboptimal. Plastic surgeons have used endoscopic brow-lift techniques for the removal of these lesions. We review our experience after adopting this endoscopic technique in a pediatric general surgery practice.We conducted a retrospective chart review of 9 consecutive outpatient procedures (5 girls and 4 boys; age range, 5 months to 12 years) between March and October 2005. Seven patients had lesions located on the lateral brow (left, n = 4; right, n = 3), 1 patient had a lesion on the left mid forehead, and 1 patient had a nasoglabellar cyst. All procedures were performed using endoscopic brow-lift equipment through a single small scalp incision 2 cm posterior to the hairline. Outcome measures included need for conversion, operative time, cosmetic outcome, and complications.All lesions (6 dermoid cysts and 3 pilomatrixomas) were successfully excised endoscopically. The mean operative time was 56 minutes (range, 22-90 minutes). There was no intraoperative or postoperative complication. All families were pleased with the cosmetic outcomes.This case report shows that endoscopic excision of forehead masses is a safe and efficacious procedure in the hands of pediatric general surgeons.

    View details for DOI 10.1016/j.jpedsurg.2006.06.047

    View details for Web of Science ID 000242395200017

    View details for PubMedID 17101362

  • Early-gestation fetal scarless wounds have less lysyl oxidase expression PLASTIC AND RECONSTRUCTIVE SURGERY Colwell, A. S., Krummel, T. M., Longaker, M. T., Lorenz, H. P. 2006; 118 (5): 1125-1129


    Lysyl oxidase cross-links collagen and elastin. Because cross-linking likely influences collagen architecture, the authors compared lysyl oxidase expression during scarless and scarring fetal dermal wound repair.Excisional dermal wounds were made on E17 (gestational day 16.5) and E19 (gestational day 18.5) mouse fetuses. Skin and wound RNA was collected at 8, 12, and 24 hours. Quantitative real-time polymerase chain reaction was performed for lysyl oxidase. The effect of transforming growth factor (TGF)-beta1 on lysyl oxidase expression in fetal fibroblasts was tested. Confluent primary fetal and postnatal fibroblast cultures were stimulated with TGF-beta1 for 24 hours, and lysyl oxidase expression was quantitated by performing real-time polymerase chain reaction. Lysyl oxidase expression was also quantitated in unwounded fetal skin to determine its expression profile during development.E17 and E19 fetal skin had approximately 2-fold greater lysyl oxidase expression than postnatal skin (p < 0.01), and fetal fibroblasts had greater baseline lysyl oxidase expression than postnatal fibroblasts. After TGF-beta1 stimulation, fetal and postnatal fibroblasts responded with increases in lysyl oxidase expression. In E17 early-gestation scarless fetal wounds, lysyl oxidase had small increases (<1.5-fold) in expression from 1 to 12 hours. In late-gestation E19 scarring fetal wounds, lysyl oxidase increased 1.8-fold at 8 hours and 2-fold at 12 hours, which was significantly greater than the changes observed in E17 scarless wounds (p < 0.01 for each).Lysyl oxidase has greater expression in E19 late-gestation wounds that heal with scar compared with E17 early-gestation scarless wounds. This suggests a role for lysyl oxidase in scar formation.

    View details for DOI 10.1097/01.prs.0000221056.27536.db

    View details for Web of Science ID 000241327600008

    View details for PubMedID 17016177

  • Novel techniques in hernia repair. Current surgery Antony, A. K., Herrera, F. A., Easter, D. W., Longaker, M. T., Lorenz, H. P. 2006; 63 (5): 306-309

    View details for PubMedID 16971199

  • Fetal and adult fibroblasts have similar TGF-beta-mediated, Smad-dependent signaling pathways 90th Annual Clinical Congress of the American-College-of-Surgeons Colwell, A. S., Krummel, T. M., Longaker, M. T., Lorenz, H. P. LIPPINCOTT WILLIAMS & WILKINS. 2006: 2277–83


    The scarless fetal skin-healing mechanism is mediated in part by the fibroblast and involves differential expression of transforming growth factor (TGF)-beta isoforms 1 and 3. The authors hypothesized that fetal and adult fibroblasts respond differently to TGF-beta isoform-specific stimulation, which may influence whether wounds scar. Connective tissue growth factor (CTGF), Smad3, and Smad7 are TGF-beta target genes. Expression of these targets was quantitated after TGF-beta1 and -beta3 stimulation of fetal and adult fibroblasts.Primary mouse fibroblast cultures at gestational day 16.5 (E17), 18.5 (E19), and 6 weeks (adult) were stimulated with TGF-beta1 or TGF-beta3. Quantitative polymerase chain reaction was performed for CTGF, Smad3, and Smad7 expression.CTGF was reduced four-fold in E17 and E19 compared with adult fibroblasts (p < 0.005). After TGF-beta1 stimulation, CTGF expression increased more than 60-fold in both E17 and E19 (p < 0.01), which was three-fold greater than that in adult fibroblasts (p < 0.005). TGF-beta3 induced more than 70-fold, 50-fold, and 20-fold increases in CTGF expression in E17, E19, and adult fibroblasts, respectively (p < 0.01 for each). Both TGF-beta1 and -beta3 decreased Smad3 expression and increased Smad7 expression in each fibroblast type, suggesting that intact TGF-beta-mediated signaling pathways were present.Fetal (E17 and E19) fibroblasts have lower CTGF expression compared with adult fibroblasts. However, fetal fibroblasts have larger increases in CTGF expression after TGF-beta1 or -beta3 stimulation. Fetal and adult mouse fibroblasts have similar TGF-beta1 and TGF-beta3 transcriptional regulation of Smad3 and Smad7. This suggests that scarless healing is likely not mediated by different Smad-dependent transcriptional responses to TGF-beta isoforms in the fetal E17 fibroblast.

    View details for DOI 10.1097/01.prs.0000224299.16523.76

    View details for Web of Science ID 000238431500026

    View details for PubMedID 16772929

  • An in vivo mouse excisional wound model of scarless healing PLASTIC AND RECONSTRUCTIVE SURGERY Colwell, A. S., Krummel, T. M., Longaker, M. T., Lorenz, H. P. 2006; 117 (7): 2292-2296


    The purpose of this study was to develop a reproducible murine model of fetal scarless wound healing.One-millimeter excisional wounds were made in fetal skin at gestational days 16.5 (E17) and 18.5 (E19) (term = day 21.5, or E22) and marked with India ink. Fetal mortality was less than 30 percent in E17 fetuses and 0 percent in E19 fetuses. Control postnatal 2-mm open wounds were made in 3-week-old mice.At 48 hours, E17 skin wounds had healed completely. E19 skin wounds also healed but were marked by skin irregularity at the wound site. Histologically, E17 wounds had fine reticular collagen architecture by trichrome staining and hair follicle regeneration. In contrast, E19 wounds healed with collagen deposition and scar formation and no hair follicle regeneration.The authors have developed a reliable mouse model of fetal scarless repair to help elucidate the mechanism of scarless wound healing to take advantage of genetically modified animals. The knowledge gained may be used to manipulate scarring in the adult to produce a more fetal-like wound.

    View details for DOI 10.1097/01.prs.0000219340.47232.eb

    View details for Web of Science ID 000238431500028

    View details for PubMedID 16772931

  • Wnt-4 expression is increased in fibroblasts after TGF-beta 1 stimulation and during fetal and postnatal wound repair PLASTIC AND RECONSTRUCTIVE SURGERY Colwell, A. S., Krummel, T. M., Longaker, M. T., Lorenz, H. P. 2006; 117 (7): 2297-2301


    Wnt-4 is a mitogen expressed during postnatal repair and scar formation; however, its expression profile during scarless repair is unknown. Transforming growth factor (TGF)-beta1 has high expression during healing with scar formation. Whether TGF-beta1 directly influences Wnt-4 expression in fetal or postnatal fibroblasts has not been examined.Primary fetal and postnatal mouse fibroblasts were stimulated with TGF-beta1 and Wnt-4 expression quantitated by real-time polymerase chain reaction. Fetal E17 and postnatal mouse excisional wounds were also analyzed for Wnt-4 expression by real-time polymerase chain reaction.In E17 fibroblasts after TGF-beta1 stimulation, Wnt-4 expression increased 4-fold at 1 hour (p < 0.05) and peaked with an 11-fold increase at 2 hours (p < 0.05). By 24 hours, expression decreased to 2-fold baseline levels (p < 0.05). In postnatal fibroblasts, Wnt-4 expression also increased after TGF-beta stimulation, but peak expression was larger and relatively delayed, with a 17-fold increase at 12 hours (p < 0.005). Expression levels at 24 hours were still 4-fold greater than baseline (p < 0.05). In E17 fetal skin, Wnt-4 expression was 3.5-fold greater compared with 3-week-old mice (p < 0.005). Small increases in Wnt-4 expression (less than 2-fold) occurred during both fetal scarless and postnatal scarring mouse wound repair.The authors' data suggest that TGF-beta directly increases Wnt-4 expression in fetal and postnatal fibroblasts and that Wnt-4 is increased in both fetal and postnatal repair.

    View details for DOI 10.1097/01.prs.0000218708.16909.31

    View details for Web of Science ID 000238431500029

    View details for PubMedID 16772932

  • Skin wounds in the MRL/MPJ mouse heal with scar WOUND REPAIR AND REGENERATION Colwell, A. S., Krummel, T. M., Kong, W., Longaker, M. T., Lorenz, H. P. 2006; 14 (1): 81-90


    Adult MRL/MpJ mice regenerate cartilage during repair of through-and-through ear punch wounds. However, the ability of this mouse strain to heal isolated cutaneous wounds by regeneration or with scar is unknown. The purpose of this study was to characterize the rate of reepithelialization and collagen architecture in dermal wounds from MRL/MpJ mice compared with C57bl/6 and Balb/c strains. Full-thickness incisional (5 mm) and excisional (2 mm diameter) skin wounds were made on the dorsum of 7-week-old MRL/MpJ, C57bl/6, and Balb/c mice. Ear punch wounds were made simultaneously on each animal. Reepithelialization was complete by 48 hours for incisional skin wounds in each strain. All excisional wounds showed incomplete reepithelialization at 24, 48, and 72 hours. At 14 days, all skin wounds had grossly healed. In contrast to the ear wounds made in C57bl/6 and Balb/c mice, MRL/MpJ ear wounds were completely healed by day 28. Dorsal skin wound sections at 14 and 28 days revealed dense collagen deposition and similar degrees of fibrosis between the three strains of mice. In conclusion, in contrast to wound healing in the ear, MRL/MpJ mouse dorsal cutaneous wounds heal similarly to C57bl/6 and Balb/c mice with dermal collagen deposition and scar formation.

    View details for DOI 10.1111/j.1743-6109.2005.00092.x

    View details for Web of Science ID 000235220000012

    View details for PubMedID 16476076

  • Comparison of scars from total hip replacements done with a standard or a mini-incision CLINICAL ORTHOPAEDICS AND RELATED RESEARCH Mow, C. S., Woolson, S. T., Ngarmukos, S. G., Park, E. H., Lorenz, H. P. 2005: 80-85


    Scar cosmesis is one of the proposed benefits of mini-incision total hip replacement as opposed to standard-incision procedures; however, there has been no scientific proof of this clinical outcome. The cosmetic appearances of healed incisions of 34 primary total hip replacement procedures done by one surgeon using either a mini-incision (20 procedures) or a standard-length incision (14 procedures) were compared at an average of 2 years postoperatively. Each scar's appearance was graded independently by two plastic surgeons using a standardized rating system. Patients answered a questionnaire regarding their subjective assessment of their scar. The blinded observers found that more mini-scars (six of 20) were rated poor than standard scars (one of 14) and that more standard-incision patients had scars that were rated good. More mini-incision patients (two of 20 versus zero of 14) had wound-healing problems. All the patients thought that their hip scar was acceptable in appearance, but 30 of 31 patients rated the relief of pain and total hip replacement longevity as higher priorities than scar cosmesis. The cosmesis of mini-incision total hip replacement scars may be inferior to standard-incision scars because of skin and soft tissue damage produced by high retractor pressures needed for exposure using a limited skin incision. Level of Evidence: Therapeutic study, Level II-2 (prospective comparative study). See the Guidelines for Authors for a complete description of levels of evidence.

    View details for DOI 10.1097/01.blo.0000191317.85422.c3

    View details for Web of Science ID 000233794700015

    View details for PubMedID 16330988

  • Hypertrophic scar fibroblasts have increased connective tissue growth factor expression after transforming growth factor-beta stimulation 49th Annual Meeting of the Plastic-Surgery-Research-Council Colwell, A. S., Phan, T. T., Kong, W., Longaker, M. T., Lorenz, P. H. LIPPINCOTT WILLIAMS & WILKINS. 2005: 1387–90


    Hypertrophic scars and keloids respond to dermal disruption with excessive collagen deposition and increased transforming growth factor (TFG)-beta expression. Connective tissue growth factor (CTGF) is a downstream mediator of TGF-beta activity that is associated with scar and fibrosis. The authors hypothesize that there is increased expression of CTGF by hypertrophic scar and keloid fibroblasts in response to TGF-beta stimulation.Primary fibroblasts were isolated in culture from human hypertrophic scar (n = 2), keloid (n = 2), and normal skin (n = 2). After 18 hours of serum starvation, the cells were stimulated with 10 ng/ml of TGF-beta1, TGF-beta2, and TGF-beta3 for 24 hours. Quantitative real-time polymerase chain reaction was performed on extracted RNA samples to assay for CTGF mRNA expression.Baseline CTGF expression was increased 20-fold in unstimulated hypertrophic scar fibroblasts and 15-fold in keloid fibroblasts compared with normal fibroblasts. CTGF expression increased greater than 150-fold when stimulated with TGF-beta1 (p < 0.002) and greater than 100-fold when stimulated by TGF-beta2 or TGF-beta3 compared with normal fibroblasts (p < 0.02 and p < 0.002, respectively). CTGF expression was greatest after TGF-beta1 stimulation in hypertrophic scar fibroblasts compared with TGF-beta2 (p < 0.04) and TGF-beta3 (p < 0.02). Keloid fibroblast CTGF expression also increased greater than 100-fold after stimulation with TGF-beta1 (p = 0.16) and greater than 75-fold after addition of TGF-beta2 and TGF-beta3 (p = 0.06 and p = 0.22, respectively).Hypertrophic scar fibroblasts have both intrinsic up-regulation of CTGF transcription and an exaggerated capacity for CTGF transcription in response to TGF-beta stimulation. These data suggest that blockage of CTGF activity may reduce pathologic scar formation.

    View details for DOI 10.1097/01.prs.0000182343.99694.28

    View details for Web of Science ID 000232421100027

    View details for PubMedID 16217483

  • Differential gene expression between scarless and scarring excisional skin wounds is revealed by microarray analysis 91st Annual Clinical Congress of the American-College-of-Surgeons Colwell, A. S., Krummel, T. M., Longaker, M. T., Lorenz, H. P. ELSEVIER SCIENCE INC. 2005: S41–S41
  • Increased angiogenesis and expression of vascular endothelial growth factor during scarless repair PLASTIC AND RECONSTRUCTIVE SURGERY Colwell, A. S., Beanes, S. R., Soo, C., Dang, C., Ting, K., Longaker, M. T., Atkinson, J. B., Lorenz, H. P. 2005; 115 (1): 204-212


    Vascular endothelial growth factor (VEGF) is a dimeric heparin-binding glycoprotein that is a potent endothelial cell-specific mitogen with increased expression during adult cutaneous wound healing. VEGF activity is mediated by two receptors, VEGFR-1 (Flt-1) and VEGFR-2 (Flk-1/KDR), which are expressed primarily in vascular endothelial cells. Initiation of profibrotic cytokine expression likely coordinates the transition from scarless healing to scar formation in fetal wounds. Angiogenesis is an important component of the scarring repair process, but the function of VEGF and degree of angiogenesis during scarless repair has not been investigated. We hypothesize that VEGF and its receptors are differentially expressed in scarless compared with scarring fetal wounds because VEGF is implicated in angiogenesis during skin development and adult wound healing. Excisional wounds were created on fetal rats at gestational ages 16.5 days (E16) and 18.5 days (E18) (term = 21.5 days). Wounds were harvested at 24 and 72 hours (n = 12 wounds per time point). Nonwounded fetal skin (E17, E19, and E21) was used as control. Reduced-cycle, specific-primer, reverse-transcriptase polymerase chain reaction was performed to determine the expression of VEGF and its receptors, VEGFR-1 and VEGFR-2. Wounds at 72 hours and fetal skin controls were examined under high-power microscopy for blood vessel counts. Unpaired two-tailed t test was used (p < 0.05 was considered significant). VEGF expression increased 2.4-fold (p < 0.001) during normal skin development from E17 to E19. In scarless wounds (E16), VEGF expression increased 2.8-fold (p < 0.02) at 72 hours. No increased expression occurred in the scarring wounds (E18). VEGFR-1 and VEGFR-2 expression increased over 2-fold during normal skin development from E17 to E21. However, each was down-regulated 30 to 50 percent in scarless (E16) and scarring (E18) wounds. There is a 2-fold increase in mean vessel counts per high-power field in scarless (E16) wounds at 72 hours compared with age-matched control skin (p < 0.02) and a 1.7-fold increase in mean vessel count in scarring fetal wounds (E18) compared with age-matched control skin (p < 0.05). There is no difference in the total number of vessels found in scarless versus scarring wounds or between 19.5-day versus 21.5-day fetal skin. VEGF and its receptors, VEGFR-1 and VEGFR-2, increase expression during skin development and dermal differentiation. VEGF expression quickly elevates during scarless compared with scarring repair, which likely contributes to the more rapid scarless fetal repair rate. Similar numbers of new ves-sels are formed during scarless and scarring fetal repair.

    View details for DOI 10.1097/01.PRS.0000138252.51581.22

    View details for Web of Science ID 000226058400028

    View details for PubMedID 15622252

  • An in vivo mouse excisional wound model of scarless healing 11th International Congress of the International-Society-of-Craniofacial-Surgery Colwell, A., Krummel, T., Longaker, M., Lorenz, H. MEDIMOND S R L. 2005: 347–349
  • Differential gene expression between scarless and scarring excisional skin wounds is revealed by microarray analysis 11th International Congress of the International-Society-of-Craniofacial-Surgery Colwell, A., Longaker, M., Krummel, T., Lorenz, H. MEDIMOND S R L. 2005: 155–158
  • Early gestation fetal searless wounds have less lysyl oxidase expression 11th International Congress of the International-Society-of-Craniofacial-Surgery Colwell, A., Krummel, T., Longaker, M., Lorenz, H. MEDIMOND S R L. 2005: 351–352
  • WNT-4 expression is increased in fibroblasts after TGF-beta1 stimulation and during fetal and postnatal wound repair 11th International Congress of the International-Society-of-Craniofacial-Surgery Colwell, A., Krummel, T., Longaker, M., Lorenz, H. MEDIMOND S R L. 2005: 373–374
  • Mammalian fetal organ regeneration REGENERATIVE MEDICINE I: THEORIES, MODELS AND METHODS Colwell, A. S., Longaker, M. T., Lorenz, H. P. 2005; 93: 83-100


    The developing fetus has the remarkable ability to heal dermal skin wounds by regenerating normal epidermis and dermis with restoration of the extracellular matrix architecture, strength, and function. The biology responsible for scarless wound healing in skin is a paradigm for ideal tissue repair. This regenerative capacity is lost in late gestation when fetal wounds heal with fibrosis and scar. Early in gestation, fetal skin is developing at a rapid pace in a unique environment. Investigation of normal skin embryogenesis and comparison between early scarless and late scarring fetal wounds has revealed distinct differences in inflammatory response, cellular mediators, wound contraction, cytokines, growth factors, and extracellular matrix modulators. The knowledge gained from comparative observational studies has served as a base for experimental interventions in animal models to induce or ameliorate scar. Although much progress has been made over the past decade, the mechanism of fetal wound healing remains largely unknown and attempts to mimic the scarless wound phenotype have not been completely successful. Identification of more key genes involved in skin regeneration may have implications in adult skin wounds and repair in other organ systems.

    View details for DOI 10.1007/b99972

    View details for Web of Science ID 000228468300004

    View details for PubMedID 15791945

  • Cyclophilin C-associated protein is a mediator for fibronectin fragment-induced matrix metalloproteinase-13 expression JOURNAL OF BIOLOGICAL CHEMISTRY Kong, W. Y., Longaker, M. T., Lorenz, H. P. 2004; 279 (53): 55334-55340


    The function of cyclophilin C-associated protein (CyC-AP) on expression of extracellular matrix and matrix metalloproteinases (MMPs) was studied in CyC-AP-null mice. Fibronectin showed increased expression of the 53- and 29-kDa fragments in skin and wounds from CyC-AP-null mice. Type I collagen had an initial degraded pattern in the skin of CyC-AP-null mice, which did not occur in wild-type mice. MMP-3, MMP-13, MMP-14, and tumor necrosis factor-alpha (TNFalpha) had a higher expression in CyC-AP-null skin. During wound healing, MMP-13 and TNFalpha were stimulated to an even higher level, suggesting they are regulated by multiple factors. To understand the regulatory mechanisms of the up-regulated MMPs, the direct effects of TNFalpha, IL-1beta, 45-kDa fibronectin fragment (FN-45), and the 70-kDa fibronectin fragments (FN-70) on the expression of MMPs were studied. MMP-13 expression increased significantly in both CyC-AP-null and wild-type dermal fibroblasts after treatment with IL-1beta or with TNFalpha. However, MMP-13 expression did not increase in CyC-AP-null fibroblasts but did increase only in wild-type fibroblasts after FN-45 and FN-70 treatment. MMP-3 activation was induced by FN-45 and did not show a difference between CyC-AP-null and wild-type fibroblasts, suggesting different regulatory pathways for FN-45 on MMP-13 and MMP-3 expression. Our data are the first to demonstrate that deletion of CyC-AP can abolish fibronectin fragment-induced MMP-13 expression through an unknown mechanism. CyC-AP is an important factor for the regulation of MMP-13 expression.

    View details for DOI 10.1074/jbc.M410804200

    View details for Web of Science ID 000225960800045

    View details for PubMedID 15507443

  • Highlights of the proceedings from the 10th International Congress of the International Society of Craniofacial Surgery. journal of craniofacial surgery Lorenz, H. P., Longaker, M. T. 2004; 15 (3): 533-537

    View details for PubMedID 15111825

  • Chondrogenic potential of multipotential cells from human adipose tissue 86th Annual Clinical Congress of the American-College-of-Surgeons Huang, J. I., Zuk, P. A., Jones, N. F., Zhu, M., Lorenz, H. P., Hedrick, M. H., Benhaim, P. LIPPINCOTT WILLIAMS & WILKINS. 2004: 585–94


    The use of stem cells for cell-based tissue-engineering strategies represents a promising alternative for the repair of cartilaginous defects. The multilineage potential of a population of putative mesodermal stem cells obtained from human lipoaspirates, termed processed lipoaspirate cells, was previously characterized. The chondrogenic potential of those cells was confirmed with a combination of histological and molecular approaches. Processed lipoaspirate cells under high-density micromass culture conditions, supplemented with transforming growth factor-beta1, insulin, transferrin, and ascorbic acid, formed well-defined nodules within 48 hours of induction and expressed the cartilaginous markers collagen type II, chondroitin-4-sulfate, and keratan sulfate. Reverse transcription polymerase chain reaction analysis confirmed the expression of collagen type II and the cartilage-specific proteoglycan aggrecan. In summary, human adipose tissue may represent a novel plentiful source of multipotential stem cells capable of undergoing chondrogenesis in vitro.

    View details for DOI 10.1097/01.PRS.0000101063.27008.E1

    View details for Web of Science ID 000220063300017

    View details for PubMedID 14758221

  • Ontogenetic transition in fetal wound transforming growth factor-beta regulation correlates with collagen organization AMERICAN JOURNAL OF PATHOLOGY Soo, C., Beanes, S. R., Hu, F. Y., Zhang, X. L., Dang, C., Chang, G., Wang, Y., Nishimura, I., Freymiller, E., Longaker, M. T., Lorenz, H. P., Ting, K. 2003; 163 (6): 2459-2476


    Fetal rat skin transitions from scarless fetal-type repair to adult-type repair with scar between day 16 (E16) and day 18 (E18) of gestation (term = 21.5 days). Deficient transforming growth factor (TGF)-beta 1 and -beta 2 injury response has been proposed as a mechanism for scarless fetal-type repair. However, previous fetal studies have inconsistently reported the degree of TGF-beta induction after injury. To minimize developmental variables in fetal versus adult TGF-beta regulation, we narrowed our study to wounded fetal animals. We hypothesize that TGF-beta ligand and receptor expression will be differentially regulated during the transition from early gestation (E16) wounds manifesting scarless fetal-type repair to late gestation (E19) wounds manifesting adult-type repair with scar. In this study, decreased and rapidly cleared TGF-beta 1 and -beta 2 expression accompanied by increased and prolonged TGF-beta 3 levels in wounded E16 animals correlated with organized collagen deposition. In contrast, increased and prolonged TGF-beta 1 and -beta 2 expression accompanied by decreased and delayed TGF-beta 3 expression in wounded E19 animals correlated with disorganized collagen architecture. Similarly, expression of TGF-beta receptors type I and II were also increased or prolonged in E19 animals. Our results implicate increased TGF-beta 1, -beta 2, and decreased TGF-beta 3 expression, as well as increased type I and II receptor expression in late gestation fetal scar formation.

    View details for Web of Science ID 000186769800032

    View details for PubMedID 14633618

    View details for PubMedCentralID PMC1892380

  • From scarless fetal wounds to keloids: Molecular studies in wound healing WOUND REPAIR AND REGENERATION Yang, G. P., Lim, I. J., Phan, T. T., Lorenz, H. P., Longaker, M. T. 2003; 11 (6): 411-418


    Surgical researchers were among the first to describe the different phases of wound healing and the events in tissue repair and regeneration that were taking place during each phase. The understanding of these events has been significantly enhanced in recent years by modern techniques in molecular and cellular biology. In this article, we discuss new findings in scarless fetal repair, angiogenesis in wound healing, and keloid pathogenesis. This serves to highlight the advances that have been made and also how much remains to be understood.

    View details for Web of Science ID 000186779200006

    View details for PubMedID 14617279

  • Tissue engineering and regenerative medicine CLINICS IN PLASTIC SURGERY Jenkins, D. D., Yang, G. P., Lorenz, H. P., Longaker, M. T., Sylvester, K. G. 2003; 30 (4): 581-?


    Regenerative medicine is evolving toward a powerful new paradigm of functional restoration. With the ethical use of gene therapy or through the manipulation of autologous tissues, improved tissue replacements may soon be available. The promise of engineered whole organs, although fraught with technical hurdles, remains on the horizon. As these advances occur, physicians and surgeons of the twenty-first century will possess ever more powerful tools to restore form and function.

    View details for DOI 10.1016/S0094-1298(03)00076-2

    View details for Web of Science ID 000186313400011

    View details for PubMedID 14621306

  • Fetal wound healing FRONTIERS IN BIOSCIENCE-LANDMARK Colwell, A. S., Longaker, M. T., Lorenz, H. P. 2003; 8: S1240-S1248


    The developing fetus has the ability to heal wounds by regenerating normal epidermis and dermis with restoration of the extracellular matrix (ECM) architecture, strength, and function. In contrast, adult wounds heal with fibrosis and scar. Scar tissue remains weaker than normal skin with an altered ECM composition. Despite extensive investigation, the mechanism of fetal wound healing remains largely unknown. We do know that early in gestation, fetal skin is developing at a rapid pace and the ECM is a loose network facilitating cellular migration. Wounding in this unique environment triggers a complex cascade of tightly controlled events culminating in a scarless wound phenotype of fine reticular collagen and abundant hyaluronic acid. Comparison between postnatal and fetal wound healing has revealed differences in inflammatory response, cellular mediators, cytokines, growth factors, and ECM modulators. Investigation into cell signaling pathways and transcription factors has demonstrated differences in tyrosine phosphorylation patterns and homeobox gene expression. Further research may reveal novel genes essential to scarless repair that can be manipulated in the adult wound and thus ameliorate scar.

    View details for Web of Science ID 000185226700062

    View details for PubMedID 12957846

  • In utero surgery for cleft lip/palate: Minimizing the "ripple effect" of scarring JOURNAL OF CRANIOFACIAL SURGERY Lorenz, H. P., Longaker, M. T. 2003; 14 (4): 504-511


    Surgical intervention is currently performed on highly selected fetuses with anatomical deformities that have a high mortality or severe morbidity when treated postnatally. In the future, in utero surgical intervention for non-life-threatening disease may become possible as fetal surgery becomes safer for the mother and fetus. Fetal cleft repair is an attractive intervention for plastic surgeons because it affords the potential to provide a scarless repair and correct the primary deformity. Furthermore, scarless fetal lip and palate repairs may prevent the ripple effect of postnatal scarring with its resultant secondary dentoalveolar and midface growth deformities. These potential benefits can dramatically reduce the number of postnatal reconstructive procedures in children with facial clefts. The rationale for a prenatal treatment approach to the patient with cleft lip/palate and the experimental evidence to support in utero intervention are discussed in this article.

    View details for Web of Science ID 000184409100019

    View details for PubMedID 12867864

  • Molecular cloning and expression of keratinocyte proline-rich protein, a novel squamous epithelial marker isolated during skin development JOURNAL OF BIOLOGICAL CHEMISTRY Kong, W. Y., Longaker, M. T., Lorenz, H. P. 2003; 278 (25): 22781-22786


    We describe a novel rat cDNA named keratinocyte proline-rich protein (KPRP) isolated by RNA differential display during skin development. We determine that KPRP is expressed in stratified squamous epithelium, and its approximately 2.8-kb cDNA encodes a 699-amino acid protein with high proline content (19%). KPRP is an insoluble protein, similar to most epidermal terminal differentiation-associated proteins. Immunoblot of the protein lysate from keratinocytes, using strong reducing conditions, demonstrates two KPRP bands of approximately 76 and 55 kDa size. KPRP is expressed in stratified squamous epithelia of skin, tongue, and esophagus. The initiation of KPRP expression in fetal rat skin at E17, E18, E19, E20, and E21 was analyzed by reverse transcription-PCR. Fetal skin at E19 and later expresses KPRP. In situ hybridization of skin from E18, E19, and 4-day-old neonatal rats demonstrates that interfollicular and follicular keratinocytes express KPRP. Anti-KPRP antibody demonstrates KPRP protein localizes to all layers of stratified epithelia in skin, tongue, and esophagus. In cultured dermal keratinocytes, KPRP is diffusely distributed throughout the cytoplasm with denser staining adjacent to the nuclear and plasma membranes. Additionally, immunoreactive intracellular granules are observed during keratinocyte detachment from their plastic substrate. Rat KPRP has 89% homology to a mouse genomic DNA sequence and 56% homology to a human hypothetical protein. We conclude that KPRP may be a new epidermal terminal differentiation-related protein expressed in stratified squamous epithelia. KPRP is expressed by fetal dermal keratinocytes during late gestation and is a new marker of maturing epidermis during fetal skin development.

    View details for DOI 10.1074/jbc.M210488200

    View details for Web of Science ID 000183503900081

    View details for PubMedID 12668678

  • Decreased expression of fibroblast and keratinocyte growth factor isoforms and receptors during scarless repair 46th Annual Meeting of Plastic-Surgery-Research-Council Dang, C. M., Beanes, S. R., Soo, C., Ting, K., Benhaim, P., Hedrick, M. H., Lorenz, H. P. LIPPINCOTT WILLIAMS & WILKINS. 2003: 1969–79


    Fibroblast growth factors (FGFs) are a family of 21 cytokines with a broad spectrum of activities, including regulation of cell proliferation, differentiation, and migration. The various FGFs bind to one or more of four different tyrosine kinase receptor types. FGFs 1, 2, 5, 7, and 10 are up-regulated during adult cutaneous wound healing. However, the expression of FGFs during fetal skin development and scarless wound healing has not been characterized. It was hypothesized that differential expression of FGF isoforms and receptors occurs during fetal skin development and that this differential expression pattern may regulate the transition from scarless repair to healing with scar formation. Excisional wounds (2 mm) were created on fetal rats at gestational days 16.5 (scarless) (one wound per fetus, n = 36 fetuses) and 19.5 (scarring) (one wound per fetus, n = 36 fetuses). Wounds were harvested at 24, 48, and 72 hours. Survival until wound harvest ranged from 66 to 75 percent for the gestational day 16 fetuses, and from 83 to 92 percent for the gestational day 19 fetuses. Nonwounded fetal skin from littermates (n = 12 fetuses per wound harvest time point) was used as the control. Wounds/skins were pooled by harvest time point, and RNA was isolated from pooled wounds/skins. Reduced-cycle, specific-primer reverse transcriptase-polymerase chain reaction was performed to determine the expression of FGF isoforms 2, 5, 7, 9, and 10 and FGF receptors 1, 2, and 4 in wounds relative to unwounded skin.In unwounded fetal skin, FGF isoform 5 expression more than doubled at birth. FGF 10 expression doubled during the transition period. FGF 7 expression increased more than sevenfold at birth. Expression of FGF isoforms 2 and 9 did not change during late fetal skin development. The expression of FGF receptors 1, 2, and 4 increased at birth. After wounding, expression of FGF isoforms 7 and 10 was down-regulated in scarless wounds, whereas FGF receptor 2 expression decreased in both scarless and scar-forming wounds. Expression of FGF isoforms 5 and 9 did not change in scarless wounds. FGF receptor 2 expression was down-regulated in both scarless and scarring wounds, but at an earlier and more sustained level in scarless wounds. Receptor type 4 expression increased in scarring wounds, whereas type 1 expression did not change in either scarless or scarring wounds. These results demonstrate an overall down-regulation of FGF expression during scarless healing.

    View details for DOI 10.1097/01.PRS.0000054837.47432.E7

    View details for Web of Science ID 000182614200024

    View details for PubMedID 12711959

  • In vitro differentiation of human processed lipoaspirate cells into early neural progenitors 46th Annual Meeting of Plastic-Surgery-Research-Council Ashjian, P. H., Elbarbary, A. S., Edmonds, B., DeUgarte, D., Zhu, M., Zuk, P. A., Lorenz, H. P., Benhaim, P., Hedrick, M. H. LIPPINCOTT WILLIAMS & WILKINS. 2003: 1922–31


    Human processed lipoaspirate (PLA) cells are multipotent stem cells, capable of differentiating into multiple mesenchymal lineages (bone, cartilage, fat, and muscle). To date, differentiation to nonmesodermal fates has not been reported. This study demonstrates that PLA cells can be induced to differentiate into early neural progenitors, which are of an ectodermal origin. Undifferentiated cultures of human PLA cells expressed markers characteristic of neural cells such as neuron-specific enolase (NSE), vimentin, and neuron-specific nuclear protein (NeuN). After 2 weeks of treatment of PLA cells with isobutylmethylxanthine, indomethacin, and insulin, about 20 to 25 percent of the cells differentiated into cells with typical neural morphologic characteristics, accompanied by increased expression of NSE, vimentin, and the nerve-growth factor receptor trk-A. However, induced PLA cells did not express the mature neuronal marker, MAP, or the mature astrocyte marker, GFAP. It was also found that neurally induced PLA cells displayed a delayed-rectifier type K+ current (an early developmental ion channel) concomitantly with morphologic changes and increased expression of neural-specific markers. The authors concluded that human PLA cells might have the potential to differentiate in vitro into cells that represent early progenitors of neurons and/or glia.

    View details for DOI 10.1097/01.PRS.0000055043.62589.05

    View details for Web of Science ID 000182614200018

    View details for PubMedID 12711954

  • New strategies for craniofacial repair and replacement: A brief review JOURNAL OF CRANIOFACIAL SURGERY Fong, K. D., Nacamuli, R. P., Song, H. J., Warren, S. M., Lorenz, H. P., Longaker, M. T. 2003; 14 (3): 333-339


    Craniofacial anomalies can severely affect the appearance, function, and psychosocial well being of patients; thus, tissue engineers are developing new techniques to functionally and aesthetically rebuild craniofacial structures. In the past decade, there have been tremendous advances in the field of tissue engineering that will substantially alter how surgeons approach craniofacial reconstruction. In this brief review, we highlight some of the preclinical recombinant protein, gene transfer, and cell-based strategies currently being developed to augment endogenous tissue repair or create structures for replacement. In addition, we discuss the importance of studying endogenous models of tissue induction and present some of the current in vitro and in vivo approaches to growing complex tissues/organs for craniofacial reconstruction.

    View details for Web of Science ID 000183221300011

    View details for PubMedID 12826804

  • Tools and techniques for craniofacial tissue engineering TISSUE ENGINEERING Warren, S. M., Fong, K. D., Chen, C. M., Loboa, E. G., Cowan, C. M., Lorenz, H. P., Longaker, M. T. 2003; 9 (2): 187-200


    Craniofacial surgery is an important conduit for tissue-engineering applications. As interdisciplinary collaborations improve, we can expect to see remarkable progress in de novo tissue synthesis, replacement, and repair. Ultimately, we may one day find that gene-modified cell-based tissue-engineering strategies will succeed today's reconstructive strategies. In this review, we highlight the major gene- and cell-based preclinical tools and techniques that are currently being developed to solve common craniofacial problems.

    View details for Web of Science ID 000182336200001

    View details for PubMedID 12740082

  • Factors determining the ultimate fate of a plastic surgery applicant PLASTIC AND RECONSTRUCTIVE SURGERY Umansky, J., Taub, P., Lorenz, H. P., Kawamoto, H. K. 2003; 111 (3): 981-984


    Plastic surgery residency program directors are frequently interested in predictors of future career direction in their applicants. Many programs strive to train leaders in academic plastic surgery. To determine what factors may predict the ultimate fate of graduating plastic surgery residents, the authors reviewed the application files of 33 former residents from a single, major plastic surgery training program. The data from 29 residents were available for analysis. Nearly half of the residents graduating from the plastic surgery training program went into private practice. Two factors, the number of years taken off for research before entering the plastic surgery residency and the presence of children, were found to be indicative of a candidate's future career path. Of particular note, there was no difference between academic graduates and nonacademic graduates with regard to their intentions in their letters of recommendation and personal statements. This information is useful to both academic program directors and resident applicants.

    View details for DOI 10.1097/01.PRS.0000046365.50385.A8

    View details for Web of Science ID 000181323800002

    View details for PubMedID 12621167

  • Fetal wound healing - Current perspectives CLINICS IN PLASTIC SURGERY Dang, C., Ting, K., Soo, C., Longaker, M. T., Lorenz, H. P. 2003; 30 (1): 13-?


    Early in gestation, fetal wounds are capable of healing scarlessly. Scarless healing in the fetus is characterized by regeneration of an organized dermis with normal appendages and by a relative lack of inflammation. Although there is a transition period between scarless and scar-forming repair, scarless healing also depends on wound size and the organ involved. The ability to heal scarlessly, furthermore, appears to be intrinsic to fetal skin. Unique characteristics of fetal fibroblasts, inflammatory cells, extra-cellular matrix, cytokine profile, and developmental gene regulation may be responsible for the scarless phenotype of early gestation fetal wounds. With the current knowledge, only minimal success has been achieved with the topical application of neutralizing antibodies, antisense oligonucleotides, and growth factors to improve wound-healing outcomes. Thus, further investigation into the mechanisms underlying scarless repair is crucial in order to devise more effective therapies for scar reduction and the treatment of cirrhosis, scleroderma, and other diseases of excessive fibrosis.

    View details for Web of Science ID 000181361100003

    View details for PubMedID 12636212

  • Genome-avide expression analysis of fetal skin development: Implications for scarless healing 10th International Congress of the International-Society-of-Craniofacial-Surgery Yun, R., Kong, W., Faudoa, R., Xia, W., Longaker, M. T., Lorenz, H. P. MEDIMOND PUBLISHING CO. 2003: 431–433
  • Fetal wound healing: Current biology WORLD JOURNAL OF SURGERY Bullard, K. M., Longaker, M. T., Lorenz, H. P. 2003; 27 (1): 54-61


    The early-gestation fetus heals dermal wounds rapidly and scarlessly. This phenomenon appears to be intrinsic to fetal skin and independent of the intrauterine environment. Unique properties of fetal cells, extracellular matrix, cytokine profile, and gene expression contribute to scarless repair. An intensive research effort has focused on unraveling the mechanisms that underlie scarless fetal wound healing in an attempt to improve the quality of healing in both children and adults.

    View details for DOI 10.1007/s00268-002-6737-2

    View details for Web of Science ID 000180270800009

    View details for PubMedID 12557038

  • Cardiac output determination in children: equivalence of the transpulmonary thermodilution method to the direct Fick principle INTENSIVE CARE MEDICINE Pauli, C., Fakler, U., Genz, T., Hennig, M., Lorenz, H. P., Hess, J. 2002; 28 (7): 947-952


    To show the equivalence of the transpulmonary thermodilution method to the direct Fick principle in children.Prospective single-centre study.A 16-bed paediatric cardiac ICU and a cardiac catheterisation laboratory at an university affiliated centre for paediatric cardiology and congenital heart disease.We consecutively investigated 18 patients (mean age 12.1 +/- 6.4 years) during cardiac catheterisation and after corrective cardiac operation.We prospectively defined limits of equivalence for cardiac index (CI) for both methods of +/- 0.25 l/min x m(2). We measured oxygen consumption for determination of CI by Fick as the clinical "gold standard" and performed a set of three transpulmonary thermodilution measurements. The mean CI(Fick) was 2.88 +/- 1.07 l/min x m(2) (range 1.10-4.62 l/min x m(2)) and CI(TPID)was 2.85 +/- 1.03 l/min x m(2)(range 1.02-4.49 l/min x m(2)). The mean difference between CI(Fick) and CI(TPID)was 0.030 +/- 0.168 l/min x m(2), and limits of agreement -0.306 to 0.366 l/min x m(2)(90% confidence interval -0.040 to 0.099 l/min x m(2)). The regression equation was : CI(Fick)=1.0244 x CI(TPID)-0.040, r(2) = 0.976, P < 0.0001. The intraclass coefficient of reliability for three repeated measurements of CI(TPID) was 0.97, the corresponding lower limit of the 95% confidence interval was 0.94.We demonstrated the equivalence of CI measurement by transpulmonary thermodilution and the Fick principle in children. This new method may improve hemodynamic monitoring and management in seriously ill children.

    View details for DOI 10.1007/s00134-002-1334-2

    View details for Web of Science ID 000177206800021

    View details for PubMedID 12122535

  • Rat extramedullary adipose tissue as a source of osteochondrogenic progenitor cells PLASTIC AND RECONSTRUCTIVE SURGERY Huang, J. I., Beanes, S. R., Zhu, M., Lorenz, H. P., Hedrick, M. H., Benhaim, P. 2002; 109 (3): 1033-1041


    Human liposuction aspirates contain pluripotent adipose-derived mesodermal stem cells that have previously been shown to differentiate into various mesodermal cell types, including osteoblasts and chondrocytes. To develop an autologous research model of bone and cartilage tissue engineering, the authors sought to determine whether rat inguinal fat pads contain a similar population of osteochondrogenic precursor cells. It was hypothesized that the rat inguinal fat pad contains adipose-derived multipotential cells that resemble human adipose-derived mesodermal stem cells in their osteochondrogenic capacity. To test this, the authors assessed the ability of cells isolated from the rat inguinal fat pad to differentiate into osteoblasts and chondrocytes by a variety of lineage-specific histologic stains. Rat inguinal fat pads were isolated and processed from Sprague-Dawley rats into a fibroblast-like cell population. Cell cultures were placed in pro-osteogenic media containing dexamethasone, ascorbic acid, and beta-glycerol phosphate. Osteogenic differentiation was assessed at 2, 4, and 6 weeks. Alkaline phosphatase activity and von Kossa staining were performed to assess osteoblastic differentiation and the production of a calcified extracellular matrix. Cell cultures were also placed in prochondrogenic conditions and media supplemented with transforming growth factor-beta1, insulin, transferrin, and ascorbic acid. Chondrogenic differentiation was assessed at 2, 7, and 14 days by the presence of positive Alcian blue staining and type II collagen immunohistochemistry. Cells placed in osteogenic conditions changed in structure to a more cuboidal shape, formed bone nodules, stained positively for alkaline phosphatase activity, and secreted calcified extracellular matrix by 2 weeks. Cells placed in chondrogenic conditions formed cartilaginous nodules within 48 hours that stained positively for Alcian blue and type II collagen. The authors identified the rat inguinal fat pad as a source of osteochondrogenic precursors and developed a straightforward technique to isolate osteochondrogenic precursors from a small animal source. This relatively easily obtained source of osteochondrogenic cells from the rat may be useful for study of tissue engineering strategies and the basic science of stem cell biology.

    View details for Web of Science ID 000174211900037

    View details for PubMedID 11884830

  • Myogenic differentiation by human processed lipoaspirate cells 45th Annual Meeting of the Plastic-Surgery-Research-Council Mizuno, H., Zuk, P. A., Zhu, M., Lorenz, H. P., Benhaim, P., Hedrick, M. H. LIPPINCOTT WILLIAMS & WILKINS. 2002: 199–209


    The use of undifferentiated cells for cell-based tissue engineering and regeneration strategies represents a promising approach for skeletal muscle repair. For such strategies to succeed, a readily available source of myogenic precursor cells must be identified. We have previously shown that cells isolated from raw human lipoaspirates, called processed lipoaspirate cells, display multilineage mesodermal potential in vitro. Because human liposuctioned fat is available in large quantities and can be harvested with low morbidity, it may be an ideal source of stem cells for tissue-engineering applications. In this study, processed lipoaspirate cells were isolated from raw lipoaspirates harvested from eight patients who underwent cosmetic surgery. Processed lipoaspirate cells were placed in promyogenic conditions for up to 6 weeks, and the expression of the myogenic markers MyoD1 and myosin heavy chain was confirmed by using structure, histology, and reverse transcriptase-polymerase chain reaction. Histologic results were quantitated as an indicator or myogenic differentiation levels. We found that induced human processed lipoaspirate cells form multinucleated cells after 3 weeks of induction, indicative of the formation of myotubes. In addition, MyoD1 and skeletal muscle myosin heavy chain are expressed at distinct time points during differentiation with MyoD1 expression preceding expression of myosin. Finally, approximately 15 percent of human processed lipoaspirate cells can be induced toward myogenic differentiation 6 weeks after induction. In summary, our findings suggest that human processed lipoaspirate cells differentiate into myogenic cells. Furthermore, these cells may be a useful source for skeletal muscle engineering and repair.

    View details for Web of Science ID 000173102600030

    View details for PubMedID 11786812

  • Confocal microscopic analysis of scarless repair in the fetal rat: Defining the transition PLASTIC AND RECONSTRUCTIVE SURGERY Beanes, S. R., Hu, F. Y., Soo, C., Dang, C. M., Urata, M., Ting, K., Atkinson, J. B., Benhaim, P., Hedrick, M. H., Lorenz, H. P. 2002; 109 (1): 160-170


    Fetal wounds pass from scarless repair to healing with scar formation during gestation. This transition depends on both the size of the wound and the gestational age of the fetus. This study defines the transition period in the fetal rat model and provides new insight into scarless collagen wound architecture by using confocal microscopy. A total of 16 pregnant Sprague-Dawley rats were operated on. Open full-thickness wounds, 2 mm in diameter, were created on fetal rats at gestational ages 14.5 days (E14; n = 10), 16.5 days (E16; n = 42), and 18.5 days (E18; n = 42) (term = 21.5 days). Wounds were harvested at 24 (n = 18 per gestational age) and 72 hours (n = 24 per gestational age). Skin at identical gestational ages to wound harvest was used for controls. The wounds were fixed and stained with hematoxylin and eosin, antibody to type I collagen, and Sirius red for confocal microscopic evaluation. No E14 rat fetuses survived to wound harvest. Wounds created on E16 fetal rats healed completely and without scarring. E16 fetal rat hair follicle formation and collagen architecture was similar to that of normal, nonwounded skin. Wounds created on E18 fetal rats demonstrated slower healing; only 50 percent were completely healed at 72 hours compared with 100 percent of the E16 fetal rat wounds at 72 hours. Furthermore, the E18 wounds healed with collagen scar formation and without hair follicle formation. Confocal microscopy demonstrated that the collagen fibers were thin and arranged in a wispy pattern in E16 fetal rat wounds and in nonwounded dermis. E18 fetal rat wounds had thickened collagen fibers with large interfiber distances. Two-millimeter excisional E16 fetal rat wounds heal without scar formation and with regeneration of normal dermal and epidermal appendage architecture. E18 fetal rat wounds heal in a pattern similar to that of adult cutaneous wounds, with scar formation and absence of epidermal appendages. Confocal microscopy more clearly defined the dermal architecture in normal skin, scarless wounds, and scars. These data further define the transition period in the fetal rat wound model, which promises to be an effective system for the study of in vivo scarless wound healing.

    View details for Web of Science ID 000173102600026

    View details for PubMedID 11786808

  • Down-regulation of decorin, a transforming growth factor-beta modulator, is associated with scarless fetal wound healing 34th Annual Meeting of the Pacific-Association-of-Pediatric-Surgeons Beanes, S. R., Dang, C., Soo, C., Wang, Y., Urata, M., Ting, K., Fonkalsrud, E. W., Benhaim, P., Hedrick, M. H., Atkinson, J. B., Lorenz, H. P. W B SAUNDERS CO-ELSEVIER INC. 2001: 1666–71


    Transforming growth factor beta (TGF-beta) bioactivity has been implicated as a potential regulator of the transition from scarless healing to scar formation in fetal wounds. Decorin is an extracellular matrix proteoglycan that regulates TGF-beta bioactivity and assists in collagen fibrillogenesis. To determine its role in scarless repair, the authors examined decorin expression in fetal fibroblasts, skin, and wounds.A single, full-thickness, 2-mm open wound was created on the dorsal surface of fetal rats at 16.5 days (E16) and 18.5 days (E18) gestational age (term, 21.5 days [E21]). Wounds were harvested at 24 and 72 hours (n = 12 wounds per time-point). Nonwounded fetal skin at E17, E19, and E21 was harvested for analysis of decorin expression during skin development and as controls for wounds. In addition, fetal (E14, E18) and adult dermal fibroblasts were cultured for in vitro analysis. Reduced-cycle, specific primer, reverse transcriptase polymerase chain reaction was performed to quantitate decorin expression.Decorin expression increased rapidly with increasing gestational age in both fetal fibroblasts and skin. Expression was increased 22-fold in E18 fibroblasts (P <.002) and 300-fold in adult fibroblasts (P <.001) compared with E14 fibroblasts. In skin, expression increased 74% (P <.01) during the fetal wound healing transition period between E17 and E19. However, in E16 wounds (scarless), decorin expression decreased 59% (P <.006) at 24 hours and 45% (P <.02) at 72 hours. Decorin expression did not change in E18 (scar) wounds at 24 and 72 hours (P >.05).Early gestation fetal fibroblasts and fetal skin express decorin at lower levels than late gestation fetal and adult fibroblasts and skin. Decorin expression is down-regulated in scarless (E16) compared with scar (E18) wounds. Thus, increased decorin expression is associated with both skin development and scar formation. Conversely, decreased decorin expression is associated with scarless repair.

    View details for Web of Science ID 000171952800016

    View details for PubMedID 11685698

  • TGF-beta isoform and receptor expression during scarless wound repair. journal of craniofacial surgery Lorenz, H. P. 2001; 12 (4): 387-388

    View details for PubMedID 11482625

  • Multilineage cells from human adipose tissue: Implications for cell-based therapies TISSUE ENGINEERING Zuk, P. A., Zhu, M., Mizuno, H., Huang, J., Futrell, J. W., Katz, A. J., Benhaim, P., Lorenz, H. P., Hedrick, M. H. 2001; 7 (2): 211-228


    Future cell-based therapies such as tissue engineering will benefit from a source of autologous pluripotent stem cells. For mesodermal tissue engineering, one such source of cells is the bone marrow stroma. The bone marrow compartment contains several cell populations, including mesenchymal stem cells (MSCs) that are capable of differentiating into adipogenic, osteogenic, chondrogenic, and myogenic cells. However, autologous bone marrow procurement has potential limitations. An alternate source of autologous adult stem cells that is obtainable in large quantities, under local anesthesia, with minimal discomfort would be advantageous. In this study, we determined if a population of stem cells could be isolated from human adipose tissue. Human adipose tissue, obtained by suction-assisted lipectomy (i.e., liposuction), was processed to obtain a fibroblast-like population of cells or a processed lipoaspirate (PLA). These PLA cells can be maintained in vitro for extended periods with stable population doubling and low levels of senescence. Immunofluorescence and flow cytometry show that the majority of PLA cells are of mesodermal or mesenchymal origin with low levels of contaminating pericytes, endothelial cells, and smooth muscle cells. Finally, PLA cells differentiate in vitro into adipogenic, chondrogenic, myogenic, and osteogenic cells in the presence of lineage-specific induction factors. In conclusion, the data support the hypothesis that a human lipoaspirate contains multipotent cells and may represent an alternative stem cell source to bone marrow-derived MSCs.

    View details for Web of Science ID 000168274200010

    View details for PubMedID 11304456

  • Biomechanics of mandibular distraction osteogenesis 3rd International Congress of Craniofacial and Maxillofacial Distraction Safa, B., Kahn, D., Lorenz, H. P., Heegaard, J. H., Kosek, J., Schendel, S. A. MEDIMOND S R L. 2001: 27–32
  • Differential expression of fibromodulin, a transforming growth factor-beta modulator, in fetal skin development and scarless repair 83rd Annual Clinical Congress of the American-College-of-Surgeons Soo, C., Hu, F. Y., Zhang, X. L., Wang, Y., Beanes, S. R., Lorenz, H. P., Hedrick, M. H., Mackool, R. J., Plaas, A., Kim, S. J., Longaker, M. T., Freymiller, E., Ting, K. ELSEVIER SCIENCE INC. 2000: 423–33


    Transforming growth factor-beta (TGF-beta1, -beta2, and -beta3) has been implicated in the ontogenetic transition from scarless fetal repair to adult repair with scar. Generally, TGF-beta exerts its effects through type I and II receptors; however, TGF-beta modulators such as latent TGF-beta binding protein-1 (LTBP-1), decorin, biglycan, and fibromodulin can bind and potentially inhibit TGF-beta activity. To more fully explore the role of TGF-beta ligands, receptors, and potential modulators during skin development and wound healing, we have used a rat model that transitions from scarless fetal-type repair to adult-type repair with scar between days 16 and 18 of gestation. We showed that TGF-beta ligand and receptor mRNA levels did not increase during the transition to adult-type repair in fetal skin, whereas LTBP-1 and fibromodulin expression decreased. In addition, TGF-beta1 and -beta3; type I, II, and III receptors; as well as LTBP-1, decorin, and biglycan were up-regulated during adult wound healing. In marked contrast, fibromodulin expression was initially down-regulated in adult repair. Immunostaining demonstrated significant fibromodulin induction 36 hours after injury in gestation day 16, but not day 19, fetal wounds. This inverse relationship between fibromodulin expression and scarring in both fetal and adult rat wound repair suggests that fibromodulin may be a biologically relevant modulator of TGF-beta activity during scar formation.

    View details for Web of Science ID 000088625100011

    View details for PubMedID 10934147

  • The impact of biomolecular medicine and tissue engineering on plastic surgery in the 21st century PLASTIC AND RECONSTRUCTIVE SURGERY Lorenz, H. P., Hedrick, M. H., Chang, J., Mehrara, B. J., Longaker, M. T. 2000; 105 (7): 2467-2481

    View details for Web of Science ID 000087277300027

    View details for PubMedID 10845305

  • Excision of the submandibular gland by an intraoral approach Annual Meeting of the Southern California Chapter of the American-College-of-Surgeons Smith, A. D., Elahi, M. M., Kawamoto, H. K., Lorenz, H. P., Hedrick, M. H. LIPPINCOTT WILLIAMS & WILKINS. 2000: 2092–95


    To improve the outcome in patients with benign diseases of the submandibular gland, we have developed an entirely intraoral technique for excision of the submandibular gland. This procedure is anatomically safe and can be performed with minimal morbidity. We believe the essential surgical steps are as follows: (1) infiltration with Xylocaine plus epinephrine with an adequate waiting period for hemostasis; (2) careful identification of the submandibular duct/lingual nerve relationship; (3) anterior retraction of the mylohyoid muscle to expose the superficial lobe; (4) superiorly directed, extraoral, manipulation of the submandibular gland; and (5) close and blunt dissection to the gland laterally to avoid injury to the facial artery and vein.

    View details for Web of Science ID 000086725000027

    View details for PubMedID 10839409

  • A single surgeon's experience with the Delaire palatoplasty 48th Annual Meeting of the California-Society-of-Plastic-Surgeons Schendel, S. A., Lorenz, H. P., Dagenais, D., Hopkins, E., Chang, J. LIPPINCOTT WILLIAMS & WILKINS. 1999: 1993–97


    The purpose of this review was to evaluate the clinical outcomes regarding velopharyngeal insufficiency and fistulization in patients with cleft palate who underwent primary repair with the one-stage Delaire palatoplasty. All patients who had a primary Delaire-type palatoplasty performed by the senior surgeon over a 10-year period (1988 to 1998) were studied. During this period, each consecutive patient with an open palatal cleft underwent the same type of repair by the same surgeon. Speech quality and velopharyngeal competence as determined by a single speech pathologist were recorded. A total of 95 patients were included in this series. The average length of follow-up was 31 months (range, 1 to 118 months). Average age at time of surgery was 13.3 months (range, 6 to 180 months). Thirty-one patients (32.6 percent) had significant associated anomalies. The average length of hospital stay was 1.9 days (range, 1 to 8 days) with a trend in recent years toward discharge on postoperative day 1. There were no intraoperative complications, either surgical or anesthetic. Three patients (3.2 percent) developed palatal fistula; none of them required repair. Six patients (6.3 percent) had velopharyngeal incompetence. In patients with more than 1 year of follow-up, the incidence of velopharyngeal incompetence was 9.2 percent (6 of 65). The incidence of fistula after the Delaire palatoplasty was lower than usually reported. The incidence of velopharyngeal incompetence requiring pharyngoplasty was equal to or lower than that seen after other types of palatoplasty, suggesting superior soft-palate muscle function attributable to approximation of the musculus uvulae. The Delaire palatoplasty results in a functional palate with low risk for fistula formation and velopharyngeal incompetence.

    View details for Web of Science ID 000083854900009

    View details for PubMedID 11149761

  • Primary and secondary orbit surgery: The transconjunctival approach 7th International Congress of the International-Society-for-Craniofacial-Surgery Lorenz, H. P., Longaker, M. T., Kawamoto, H. K. LIPPINCOTT WILLIAMS & WILKINS. 1999: 1124–28


    The transconjunctival approach to the orbit is underutilized because of concern regarding inadequate exposure and higher postoperative rates of lower eyelid shortening and ectropion. All patients who had a transconjunctival incision performed for orbital surgery over the last 6 years (1990 to 1996) were studied. Patients who had a transconjunctival blepharoplasty were excluded. A total of 35 patients, average age 32 years, had 45 transconjunctival incisions performed. Lateral canthotomy or cantholysis was not done. Operations fell into three categories: fracture plating alone, 10 (22 percent); split-calvarial bone graft placement with or without plating, 26 (58 percent); and orbital decompression, 9 (20 percent). The overall incidence of ectropion was 6.7 percent (3 of 45). One patient (2 percent) had transient ectropion, and two patients (4 percent) had persistent ectropion, which required surgical correction. Ectropion occurred only in those lower eyelids that had a previous transcutaneous incision (3 of 18 = 17 percent). None occurred in those eyelids that had no prior incision or only a previous transconjunctival incision. The transconjunctival approach without a lateral canthotomy provides safe access to the orbit in eyelids that have not had a previous transconjunctival incision.

    View details for Web of Science ID 000079107900003

    View details for PubMedID 10088496

  • Transconjunctival approach to orbital surgery: Ectropion incidence increases in lids with a previous subciliary incision 7th International Congress of the International-Society-for-Craniofacial-Surgery Lorenz, H. P., Longaker, M. T., Kawamoto, H. K. MONDUZZI EDITORE. 1997: 243–245


    Human fetal skin heals without scar formation when it is transplanted to a subcutaneous location on an adult athymic mouse and subsequently wounded. In contrast, human fetal skin of identical gestational age heals with scar formation when transplanted to a cutaneous location on the athymic mouse recipient. To determine if mouse (adult) or human (fetal) fibroblasts are healing the graft wounds, we performed indirect immunohistochemistry for mouse and human collagen types I and III. Full-thickness skin grafts (n = 51) from human fetuses at 18 weeks' (n = 4) or 24 weeks' (n = 2) gestational age were placed onto athymic mice in two locations: cutaneously onto a fascial bed and subcutaneously in a pocket under the murine panniculus carnosus. Linear incisions were made in each graft 7 days after transplantation. Grafts were harvested at 7, 14, and 21 days after wounding and stained with hematoxylin and eosin or Mallory's trichrome. Immunohistochemistry for either human collagen type I or type III or for mouse collagen type I was performed. The subcutaneous grafts healed with human collagen types I and III in a scarless pattern. The wound collagen pattern was reticular and unrecognizable from the surrounding dermis. Hair follicles and sebaceous gland patterns were unchanged in the wounded dermis. Conversely, the cutaneous grafts healed with mouse collagen in a scar pattern with disorganized collagen fibers and no appendages. Mouse collagen scar was present along the base of the cutaneous grafts and as a thin capsule around the subcutaneous grafts. We conclude that (1) subcutaneous grafts heal with human fetal collagen and no scar formation, and (2) cutaneous grafts heal with mouse collagen in a scar pattern. Fetal fibroblasts can heal fetal skin wounds without scar despite being perfused by adult serum and inflammatory cells in an adult environment. These data suggest that the fetal fibroblast is the major effector cell for scarless fetal skin repair.

    View details for Web of Science ID A1995TC73600001

    View details for PubMedID 7480221



    Fetal skin wounds heal without scarring. To determine the role of TGF-beta 1 in fetal wound healing, mRNA expression of TGF-beta 1 was analyzed in human fetal and adult skin wounds.Human fetal skin transplanted to a subcutaneous location on an adult athymic mouse that was subsequently wounded heals without scar, whereas human adult skin heals with scar formation in that location. In situ hybridization for TGF-beta 1 mRNA expression and species-specific immunohistochemistry for fibroblasts, macrophages, and neutrophils were performed in human adult wounds, fetal wounds, and fetal wounds treated with a TGF-beta 1 slow release disk.Transforming growth factor-beta 1 mRNA expression was induced by wounding adult skin. No TGF-beta 1 mRNA upregulation was detected in human fetal skin after wounding. However, when exogenous TGF-beta 1 was added to human fetal skin, induction of TGF-beta 1 mRNA expression in human fetal fibroblasts occurred, an adult-like inflammatory response was detected, and the skin healed with scar formation.Transforming growth factor-beta 1 is an important modulator in scar formation. Anti-TGF-beta 1 strategies may promote scarless healing in adult wounds.

    View details for Web of Science ID A1995RM73400006

    View details for PubMedID 7639582

  • Spatial and temporal expression of transforming growth factor-beta isoforms during ovine excisional and incisional wound repair. Wound repair and regeneration McMullen, H., Longaker, M. T., Cabrera, R. C., Sung, J., Canete, J., Siebert, J. W., Lorenz, H. P., Gold, L. I. 1995; 3 (2): 141-156


    To elucidate the role for transforming growth factor-beta isoforms (beta(1), -beta(2), and -beta(3)) in wound repair, we used isoform-specific antibodies to detect the spatial and temporal expression of the latent and mature/active transforming growth factor-beta isoforms by immunohistochemical localization through 21 days after excisional and incisional wounding of ovine skin. Although incisional and excisional wounds showed similar patterns of transforming growth factor-beta immunoreactivity, we found a differential temporal and spatial expression of the latent and mature transforming growth factor-beta isoforms throughout wound repair. Specifically, 1 day after wounding, there was a marked increase in transforming growth factor-beta isoforms in the epithelium adjacent to the wound, epidermal appendages, and the cells and matrix of the granulation tissue. At this time, transforming growth factor-beta(3) isoform was the most abundant. Most notably, the epidermis adjacent to the wound was intensely immunoreactive for all transforming growth factor-beta isoforms 1 day after injury. However, the migrating epithelium, derived from both the hair follicles and the wound margins, was completely devoid of immunoreactive transforming growth factor-beta until reepithelialization was complete. Within the inflammatory exudate, there was a distinct band of leukocytes that was immunoreactive for transforming growth factor-beta(2) and -beta(3) 1 day after injury and 1 day later for transforming growth factor-beta(1). Although transforming growth factor-beta(1) and -beta(2), latent transforming growth factor-beta(2), transforming growth factor-beta(3), and latent transforming growth factor-beta(3) immunostaining was present in the numerous fibroblasts and other dermal cells, latent transforming growth factor-beta(1) was only associated with the extracellular matrix. In general, immunoreactivity remained high until day 7 after wounding and slowly subsided over time. However, by day 21, immunostaining had not returned to normal and the original wound was replete with immunoreactive fibroblasts and a dense, immunostained extracellular matrix. Thus, although the dynamic presence of transforming growth factor-beta isoforms exemplifies its positive role in the wound repair process, its persistence together with its known potent effects on matrix accumulation, supports its role in scar formation.

    View details for PubMedID 17173643

  • SCAR FORMATION IN THE FETAL ALIMENTARY-TRACT 41st Annual International Congress of the British-Association-of-Paediatric-Surgeons Meuli, M., Lorenz, H. P., Hedrick, M. H., Sullivan, K. M., Harrison, M. R., Adzick, N. S. W B SAUNDERS CO. 1995: 392–95


    The aim of this study was to determine whether the fetal alimentary tract shares the unique scarless healing properties of fetal skin. Full-thickness incisional gastric wounds were created and sutured closed in fetal lambs at 60, 75, and 120 days' gestation (full term, 145 days), and in adult control sheep. At the time of harvest, 14 days postwounding, dense fibrous adhesions were found intraperitoneally in all fetal and adult animals. Histologically, all fetal and adult gastric wounds healed with pronounced scar formation. In contrast to the adult wound, there was no significant inflammatory response in the fetal wounds. Because scar formed in the absence of inflammation in fetal gastric wounds, there is no obvious relation between scarring and the inflammatory response at this location. This study shows that not all fetal tissues exhibit scarless repair properties.

    View details for Web of Science ID A1995QM21100004

    View details for PubMedID 7760227



    This review updates the surgeon about the cellular, matrix, and growth factor components of scarless fetal wound repair.Fetal skin wound healing is characterized by the absence of scar tissue formation. This unique repair process is not dependent on the sterile, aqueous intrauterine environment. The differences between fetal and adult skin wound healing appear to reflect processes intrinsic to fetal tissue, such as the unique fetal fibroblasts, a more rapid and ordered deposition and turnover of tissue components, and, particularly, a markedly reduced inflammatory infiltrate and cytokine profile. Scarless fetal wounds are relatively deficient in the inflammatory cytokine, transforming growth factor beta (TGF-beta). In contrast, the fibrosis characteristic of adult wound repair may be associated with TGF-beta excess. Recent experimental studies suggest that specific anti-TGF-beta therapeutic strategies can ameliorate scar formation in adult wound repair and fibrotic diseases. Inhibitors of TGF-beta may be important future drugs to control scar.Based on the scarless fetal wound repair model, a number of ways in which the matrix and cellular response of the healing adult wound might be manipulated to reduce scarring are reviewed.

    View details for Web of Science ID A1994NU60400003

    View details for PubMedID 8024353

  • ADULT SKIN WOUNDS IN THE FETAL ENVIRONMENT HEAL WITH SCAR FORMATION ANNALS OF SURGERY Longaker, M. T., Whitby, D. J., Ferguson, M. W., Lorenz, H. P., Harrison, M. R., Adzick, N. S. 1994; 219 (1): 65-72


    This study investigated the influence of the fetal environment on the healing characteristics of adult skin.The remarkable ability of the fetus to heal without scarring is poorly understood. The unique qualities of fetal wound healing may be caused by the fetal environment, the fetal tissues, or a combination of both. There are numerous differences between the prenatal and postnatal environments that may play a role in the unique fetal response to injury.Full-thickness adult sheep skin was transplanted onto the backs of 60-day-gestation fetal lambs (term, 145 days of gestation). The adult skin grafts were thus perfused by fetal blood and bathed in amniotic fluid. Previous work has demonstrated that, before midgestation, fetal lambs do not reject allogenic skin grafts. Forty days later (100 days of gestation), incisional wounds were made on both the adult skin graft and the adjacent fetal skin. The wounds were harvested 14 days postwounding and analyzed by both light microscopy and immunohistochemical testing using antibodies to collagen types I, III, and VI.The wounds in the adult skin grafts healed with scar formation. This observation contrasts strongly with the scarless healing of the incisional fetal skin wounds.This study suggests that scarless fetal skin healing properties are intrinsic to fetal skin and are not primarily the result of the fetal environment.

    View details for Web of Science ID A1994MR31400011

    View details for PubMedID 8297179



    Sequential surgical procedures in cleft lip/palate (CL/P) patients result in scar formation that is believed to be associated with midface growth retardation. By use of a previously developed fetal lamb model, wound healing characteristics were investigated after in utero CL repair. It is hypothesized that scarless healing after fetal CL repair occurs without inflammation and scar formation. CL wounds were created in mid-second-trimester fetal lambs and either repaired in three layers (mucosa, muscle, and skin) or left unrepaired. Fetuses were then harvested at 7, 14, and 21 days postoperatively, and the wound site was examined microscopically. When created at 75 days' gestation (term = 145 days), fetal lamb CL wounds heal rapidly without inflammation and scar formation. By day 21 postoperatively, there was complete regeneration of skin, muscle, and mucosa, as well as epidermal appendages. With this model, it will be possible to compare the effects of scarless fetal CL repair with those of postnatal repair on midface growth.

    View details for Web of Science ID A1993MQ61100016

    View details for PubMedID 8106816



    The ability of a fetus to heal without scar formation depends on its gestational age at the time of injury and the size of the wound defect. In general, linear incisions heal without scar until late in gestation whereas excisional wounds heal with scar at an earlier gestational age. The profiles of fetal proteoglycans, collagens, and growth factors are different from those in adult wounds. The less-differentiated state of fetal skin is probably an important characteristic responsible for scarless repair. There is minimal inflammation in fetal wounds. Fetal wounds are characterized by high levels of hyaluronic acid and its stimulator(s) with more rapid, highly organized collagen deposition. The roles of peptide growth factors such as transforming growth factor-beta and basic fibroblast growth factor are less prominent in fetal than in adult wound healing. Platelet-derived growth factor has been detected in scarless fetal skin wounds, but its role is unknown. An understanding of scarless tissue repair has possible clinical application in the modulation of adult fibrotic diseases and abnormal scar-forming conditions.

    View details for Web of Science ID A1993MA37000014

    View details for PubMedID 8236977

  • FETAL WOUND-HEALING - THE ONTOGENY OF SCAR FORMATION IN THE NONHUMAN PRIMATE ANNALS OF SURGERY Lorenz, H. P., Whitby, D. J., Longaker, M. T., Adzick, N. S. 1993; 217 (4): 391-396


    This study determined how scar formation develops in a non-human primate model of fetal skin repair.A transition from healing scarlessly to healing with scar formation characterizes skin repair in rat and sheep fetuses. New knowledge of the regulatory processes occurring in the fetal wound at the initial stages of scar formation may provide insights into the early mechanisms of scar formation.Full-thickness wounds were made in fetal rhesus monkey lips from 75 through 114 days gestation (n = 6, term = 165 days). Wounds were harvested at 14 days postwounding and processed for histology (hematoxylin & eosin, Masson's trichrome) as well as immunohistochemistry (human type I or type III collagen).Wounds healed with complete restoration of normal tissue architecture in the 75-day gestation fetus. However in the 85-100 day gestation fetuses, wounds healed with an absence of hair follicles and sebaceous glands, but the dermal collagen pattern remained reticular and similar to that in unwounded dermis. At 107 days, a thin scar was present in the wound, thereby demonstrating a transition to scar formation between 100 and 107 days gestation (early 3rd trimester) in the non-human primate.In the non-human primate fetus, a transition from scarless repair to adult-type repair with scar formation occurs in the early third trimester. These data provide insight into the transition process; the ontogeny of scar formation is characterized initially by wounds healing without the presence of epidermal appendages but with a normal reticular dermal collagen pattern, which we term the "transition wound."

    View details for Web of Science ID A1993KY26600011

    View details for PubMedID 8466310

  • Open human fetal surgery. Advances in surgery Lorenz, H. P., Adzick, N. S., Harrison, M. R. 1993; 26: 259-273

    View details for PubMedID 8418566



    Diagnosis and treatment of fetal disease processes has advanced dramatically, but the ability to monitor the fetus in utero remains rudimentary. Open fetal operation provides a unique opportunity to correct life-threatening fetal abnormalities, but it also places the fetus at risk. Continuous intraoperative and post-operative fetal electrocardiographic monitoring may decrease the risk by optimizing fetal and maternal perioperative management. We tested an implantable radiotelemetry device that allowed continuous intraoperative and postoperative fetal electrocardiographic and temperature monitoring. The radiotelemetry device was placed subcutaneously in four fetal sheep at 100 to 112 days' gestation (term equals 145 days). During and after the fetal operation, the monitor reliably and continuously transmitted the analog fetal electrocardiogram and temperature. We then tested a similar device during human fetal operations on both an acute and a chronic basis. The radiotelemetry device permits continuous and reliable fetal monitoring during and after fetal operation and we now consider it essential to the operation. Its use should facilitate optimal fetal and maternal management and improve survival of the fetus.

    View details for Web of Science ID A1993KF80400010

    View details for PubMedID 8427006

  • A MODEL FOR FETAL CLEFT-LIP REPAIR IN LAMBS PLASTIC AND RECONSTRUCTIVE SURGERY Longaker, M. T., Stern, M., Lorenz, H. P., Whitby, D. J., Dodson, T. B., Harrison, M. R., Adzick, N. S., Kaban, L. B. 1992; 90 (5): 750-756


    Fetal wounds heal without inflammation and scar formation. This phenomenon may, in the future, be applicable to human cleft lip and palate repair. However, extensive experimental work must first be done to document the benefits of in utero repair. We developed a large animal model for creation and repair of a complete cleft lip and alveolus using fetal lambs. The cleft lip and alveolus deformity was created in eight 75-day-gestation fetuses (term = 145 days) and either repaired in three layers or left unrepaired. There were four sham-operated fetuses, and all animals were alive at harvest. Repaired, unrepaired, and control fetuses were harvested at 7, 14, 21, and 70 days following surgery. The unrepaired fetuses demonstrated a complete cleft lip and alveolus with an oronasal fistula. The maxilla was asymmetrical, with the greater segment deviated toward the cleft and with decreased anterior maxillary width. In contrast, repaired cleft lip and alveolus animals showed no scar, normal thickness of the lip, and a symmetrical maxilla. Histologic analysis of the repaired wounds showed evidence of tissue regeneration without scar formation. The results of this preliminary study indicate that the fetal lamb cleft lip and alveolus model is technically feasible with an excellent survival rate. Healing occurs without scar formation. In the repaired animals, the maxilla was symmetrical. This model will be used to document facial growth following in utero repair of a cleft lip and alveolus.

    View details for Web of Science ID A1992JW18000003

    View details for PubMedID 1410026

  • ENDOSCOPIC CREATION AND REPAIR OF FETAL CLEFT-LIP PLASTIC AND RECONSTRUCTIVE SURGERY Estes, J. M., Whitby, D. J., Lorenz, H. P., Longaker, M. T., Szabo, Z., Adzick, N. S., Harrison, M. R. 1992; 90 (5): 743-746


    In utero repair of several life-threatening malformations in the human fetus is now a clinical reality, yet fetal surgery still poses significant risks to both the mother and the unborn child. Preterm labor is a major problem and is directly related to the large hysterotomy required for fetal exposure. Endoscopic surgical manipulation of the fetus, through small uterine "ports," solves this problem and may eventually permit fetal intervention for non-life-threatening malformations. In this pilot study we demonstrated the feasibility of performing endoscopic surgery on the fetus in situ. A lip incision was created and repaired using endoscopic microsurgical techniques in midgestation fetal lambs. This represents the first application of this technique for in utero fetal intervention.

    View details for Web of Science ID A1992JW18000001

    View details for PubMedID 1410025



    Optimal fetal management during and after fetal surgery has been limited by an inability to reliably monitor the fetal heart rate and temperature, and by a lack of access to the fetal circulation. In order to solve these problems, we used early third trimester fetal sheep to develop: (1) an implantable radiotelemetry device that transmits the fetal electrocardiogram and temperature, and (2) an intraosseous access technique. A miniaturized radiotelemeter was implanted subcutaneously in the axilla of four fetal sheep. Safe implantation of the radiotelemeter was technically feasible and the device reliably recorded the fetal electrocardiogram and temperature both intraoperatively and postoperatively. Although many possible routes for access to the fetal circulation have been tried experimentally and clinically for both resuscitation and blood sampling, none have proven satisfactory. We assessed the use of intraosseous access in fetal sheep (n = 6) for both infusion and blood sampling. Access with an intraosseous needle was obtained in both sheep fetuses and human fetal cadavers. Blood gas values (pH, PCO2, and PO2) obtained from the medullary cavity of fetal sheep accurately reflected peripheral venous values. Resuscitation drugs reached the fetal circulation via the intraosseous route: sodium bicarbonate elevated venous bicarbonate levels from 28.4 +/- 1.7 to 31.8 +/- 2.1 mEq/dL (P < .05); injected glucose increased venous glucose levels by 520 +/- 108 mg/dL (P < .01); and injection of calcium chloride elevated venous calcium levels from 11.8 +/- 0.7 to 15.2 +/- 2.2 mEq/dL (P < .05).(ABSTRACT TRUNCATED AT 250 WORDS)

    View details for Web of Science ID A1992JR78000021

    View details for PubMedID 1403515



    Babies born with severe pulmonary hypoplasia are unsalvageable despite maximal therapy including extracorporeal membrane oxygenation (ECMO). Using ECMO as a bridge to transplantation, reduced-size lung grafts (pulmonary lobe or segment) could expand the pool of cadaver donors and may allow for HLA-matched living-related transplants. We tested this concept first in the piglet model and developed the technical maneuvers necessary to perform lobar and segmental lung transplants from adult pigs into neonatal piglets. Prior to clinical application, a systematic evaluation of anatomic considerations for reduced-size human lung transplantation was needed. A series of human adult and neonatal cadaver thoracic dissections were performed to determine the adult pulmonary lobe or segment with the proper size, orientation, and vascular and bronchial anatomy for use as a neonatal lung transplant. The adult right middle lobe (RML) is the best candidate for neonatal left lung replacement. The adult RML, once removed, can be rotated 180 degrees around its superior-inferior axis and the vessels and bronchus align well in the left chest of the neonate. The RML may require further reduction to fit into the neonatal left chest. Selective arterial perfusion of the RML showed the anterior segment to be a near-perfect match for fit and anatomy. This technique may eventually permit living-related lung transplantation.

    View details for Web of Science ID A1992JR78000007

    View details for PubMedID 1403504

  • Emergency thoracotomy: survival correlates with physiologic status. journal of trauma Lorenz, H. P., Steinmetz, B., Lieberman, J., Schecoter, W. P., Macho, J. R. 1992; 32 (6): 780-785


    Emergency thoracotomy is a standard procedure in the management of cardiac arrest in patients sustaining severe trauma. We examined the records of 463 moribund trauma patients treated at our institution from 1980 to 1990 to refine indications for emergency thoracotomy. Patients underwent thoracotomy either in the emergency department (ED) (n = 424) or in the operating room (OR) (n = 39) as a component of continuing resuscitation after hospital arrival. The survival rate was 13% (61 of 463) overall, 2% (3 of 193) for blunt, 22% (58 of 269) for all penetrating, 8% (10 of 131) for gunshot, 34% (48 of 141) for stab-wound patients, and 54% (21 of 39) for patients who underwent emergency thoracotomy in the OR. Survival correlated with the physiologic status of patients both on initial evaluation in the field by paramedics and on arrival at the ED. Patients with penetrating trauma and in profound shock (BP less than 60 mm Hg) or mild shock (BP 60-90 mm Hg) with subsequent cardiac arrest had survival rates of 64% (27 of 42) and 56% (30 of 54), respectively. None of the patients with absent signs of life, defined as full cardiopulmonary arrest with absent reflexes (n = 215), on initial assessment by paramedics in the field, survived. We conclude that (1) no emergency thoracotomy should be performed if no signs of life are present on the initial prehospital field assessment; (2) emergency thoracotomy is an indicated procedure in most patients sustaining penetrating trauma; (3) blunt traumatic cardiac arrest is a relative contraindication to emergency thoracotomy.

    View details for PubMedID 1613839