Dr. Dunn obtained his B.S. degree in Biology and Chemical Engineering from the California Institute of Technology and his M.D. and Ph.D. degrees from Harvard and Massachusetts Institute of Technology. He trained in General Surgery at the UCLA School of Medicine and in Pediatric Surgery at the Riley Hospital for Children in Indianapolis. He was the Professor and Chief of Pediatric Surgery at UCLA, with a joint appointment in the Department of Bioengineering until 2016. Dr. Dunn served as the Susan B. Ford Surgeon-in-Chief at the Lucile Packard Children's Hospital from 2016 to 2022. He is the John A. and Cynthia Fry Gunn Director of Pediatric Surgery, and Professor of Surgery and Bioengineering at the Stanford School of Medicine.

Clinical Focus

  • Pediatric Surgery
  • Short Bowel Syndrome
  • Intestinal Motility Disorders

Academic Appointments

Administrative Appointments

  • Chief of Pediatric Surgery, Department of Surgery, Stanford (2016 - Present)
  • Surgeon-in-Chief, Lucile Packard Children's Hospital (2016 - 2022)

Boards, Advisory Committees, Professional Organizations

  • Member, Child Health Research Institute Executive Committee (2016 - 2022)

Professional Education

  • B.S., California Institute of Technology, Biology and Chemical Engineering (1985)
  • M.D., Harvard Medical School, Medicine (1992)
  • Ph.D., Massachusetts Institute of Technology, Medical Engineering (1992)
  • Residency: UCLA Health Sciences (1999) CA
  • Board Certification: American Board of Surgery, General Surgery (2000)
  • Fellowship: Riley Hospital for Children at Indiana University Health (2001) IN
  • Board Certification: American Board of Surgery, Pediatric Surgery (2002)


  • James Dunn. "United States Patent 9,138,336 Expandable distension device for hollow organ growth", Sep 22, 2015

Current Research and Scholarly Interests

Intestinal lengthening for short bowel syndrome
Intestinal stem cell therapy for intestinal failure
Skin derived precursor cell therapy for enteric neuromuscular dysfunction
Intestinal tissue engineering

2023-24 Courses

Stanford Advisees

Graduate and Fellowship Programs

All Publications

  • Effect of air-liquid interface on cultured human intestinal epithelial cells. FASEB bioAdvances Sabapaty, A., Lin, P. Y., Dunn, J. C. 2024; 6 (2): 41-52


    The intestinal epithelium is a dynamic barrier that allows the selective exchange of ions, hormones, proteins, and nutrients. To accomplish this, the intestinal epithelium adopts a highly columnar morphology which is partially lost in submerged culturing systems. To achieve this, small intestinal tissue samples were utilized to obtain human intestinal crypts to form enteroids. The Transwell system was subsequently employed to form a monolayer of cells that was cultured in either the submerged condition or the air-liquid Interface (ALI) condition. We found that the human intestinal monolayer under the ALI condition exhibited morphology more similar to the normal intestinal epithelium. F-actin localization and brush border formation were observed apically, and the integrity of the tight junctions was preserved in the ALI condition. Fewer apoptotic cells were observed in the ALI conditions as compared to the submerged conditions. The monolayer of cells expressed a higher level of secretory cell lineage genes in the ALI condition. The ALI condition positively contributes toward a more differentiated phenotype of epithelial cells. It serves as an amplifier that enhances the existing differentiation cue. The ALI system provides a more differentiated platform to study intestinal function compared to submerged conditions.

    View details for DOI 10.1096/fba.2023-00132

    View details for PubMedID 38344411

    View details for PubMedCentralID PMC10853644

  • Mechanosensitivity and Adaptive Capacity of the Intestinal Wall in a Partial Obstruction Murine Model Shariatzadeh, S., Thomas, A. A., Lopez, N. D., Martin, M. G., Dunn, J. C. LIPPINCOTT WILLIAMS & WILKINS. 2023: S356
  • Non-Canonical Ciliary-Mediated Hedgehog Signaling Underlying Cecal Lengthening Shariatzadeh, S., Thomas, A. A., Portelli, K., Wood, L., Park, J., Dunn, J. C. LIPPINCOTT WILLIAMS & WILKINS. 2023: S373
  • Spiral NeuroString: High-Density Soft Bioelectronic Fibers for Multimodal Sensing and Stimulation. bioRxiv : the preprint server for biology Khatib, M., Zhao, E. T., Wei, S., Abramson, A., Bishop, E. S., Chen, C., Thomas, A., Xu, C., Park, J., Lee, Y., Hamnett, R., Yu, W., Root, S. E., Yuan, L., Chakhtoura, D., Kim, K. K., Zhong, D., Nishio, Y., Zhao, C., Wu, C., Jiang, Y., Zhang, A., Li, J., Wang, W., Salimi-Jazi, F., Rafeeqi, T. A., Hemed, N. M., Tok, J. B., Chen, X., Kaltschmidt, J. A., Dunn, J. C., Bao, Z. 2023


    Bioelectronic fibers hold promise for both research and clinical applications due to their compactness, ease of implantation, and ability to incorporate various functionalities such as sensing and stimulation. However, existing devices suffer from bulkiness, rigidity, limited functionality, and low density of active components. These limitations stem from the difficulty to incorporate many components on one-dimensional (1D) fiber devices due to the incompatibility of conventional microfabrication methods (e.g., photolithography) with curved, thin and long fiber structures. Herein, we introduce a fabrication approach, ‶spiral transformation, to convert two-dimensional (2D) films containing microfabricated devices into 1D soft fibers. This approach allows for the creation of high density multimodal soft bioelectronic fibers, termed Spiral NeuroString (S-NeuroString), while enabling precise control over the longitudinal, angular, and radial positioning and distribution of the functional components. We show the utility of S-NeuroString for motility mapping, serotonin sensing, and tissue stimulation within the dynamic and soft gastrointestinal (GI) system, as well as for single-unit recordings in the brain. The described bioelectronic fibers hold great promises for next-generation multifunctional implantable electronics.

    View details for DOI 10.1101/2023.10.02.560482

    View details for PubMedID 37873341

  • Allometrically scaling tissue forces drive pathological foreign-body responses to implants via Rac2-activated myeloid cells. Nature biomedical engineering Padmanabhan, J., Chen, K., Sivaraj, D., Henn, D., Kuehlmann, B. A., Kussie, H. C., Zhao, E. T., Kahn, A., Bonham, C. A., Dohi, T., Beck, T. C., Trotsyuk, A. A., Stern-Buchbinder, Z. A., Than, P. A., Hosseini, H. S., Barrera, J. A., Magbual, N. J., Leeolou, M. C., Fischer, K. S., Tigchelaar, S. S., Lin, J. Q., Perrault, D. P., Borrelli, M. R., Kwon, S. H., Maan, Z. N., Dunn, J. C., Nazerali, R., Januszyk, M., Prantl, L., Gurtner, G. C. 2023


    Small animals do not replicate the severity of the human foreign-body response (FBR) to implants. Here we show that the FBR can be driven by forces generated at the implant surface that, owing to allometric scaling, increase exponentially with body size. We found that the human FBR is mediated by immune-cell-specific RAC2 mechanotransduction signalling, independently of the chemistry and mechanical properties of the implant, and that a pathological FBR that is human-like at the molecular, cellular and tissue levels can be induced in mice via the application of human-tissue-scale forces through a vibrating silicone implant. FBRs to such elevated extrinsic forces in the mice were also mediated by the activation of Rac2 signalling in a subpopulation of mechanoresponsive myeloid cells, which could be substantially reduced via the pharmacological or genetic inhibition of Rac2. Our findings provide an explanation for the stark differences in FBRs observed in small animals and humans, and have implications for the design and safety of implantable devices.

    View details for DOI 10.1038/s41551-023-01091-5

    View details for PubMedID 37749310

    View details for PubMedCentralID 2966551

  • Organoid modeling of lung-resident immune responses to SARS-CoV-2 infection. Research square Choi, S. S., van Unen, V., Zhang, H., Rustagi, A., Alwahabi, S. A., Santos, A. J., Chan, J. E., Lam, B., Solis, D., Mah, J., Röltgen, K., Trope, W., Guh-Siesel, A., Lin, Z., Beck, A., Edwards, C., Mallajosyula, V., Martin, B. A., Dunn, J. C., Shrager, J., Baric, R. A., Pinsky, B., Boyd, S. D., Blish, C. A., Davis, M. M., Kuo, C. J. 2023


    Tissue-resident immunity underlies essential host defenses against pathogens, but analysis in humans has lacked in vitro model systems where epithelial infection and accompanying resident immune cell responses can be observed en bloc. Indeed, human primary epithelial organoid cultures typically omit immune cells, and human tissue resident-memory lymphocytes are conventionally assayed without an epithelial infection component, for instance from peripheral blood, or after extraction from organs. Further, the study of resident immunity in animals can be complicated by interchange between tissue and peripheral immune compartments. To study human tissue-resident infectious immune responses in isolation from secondary lymphoid organs, we generated adult human lung three-dimensional air-liquid interface (ALI) lung organoids from intact tissue fragments that co-preserve epithelial and stromal architecture alongside endogenous lung-resident immune subsets. These included T, B, NK and myeloid cells, with CD69+CD103+ tissue-resident and CCR7- and/or CD45RA- TRM and conservation of T cell receptor repertoires, all corresponding to matched fresh tissue. SARS-CoV-2 vigorously infected organoid lung epithelium, alongside secondary induction of innate cytokine production that was inhibited by antiviral agents. Notably, SARS-CoV-2-infected organoids manifested adaptive virus-specific T cell activation that was specific for seropositive and/or previously infected donor individuals. This holistic non-reconstitutive organoid system demonstrates the sufficiency of lung to autonomously mount adaptive T cell memory responses without a peripheral lymphoid component, and represents an enabling method for the study of human tissue-resident immunity.

    View details for DOI 10.21203/

    View details for PubMedID 37205380

    View details for PubMedCentralID PMC10187413

  • Stem cell activation during distraction enterogenesis in the murine colon. Pediatric surgery international Salimi-Jazi, F., Thomas, A. L., Rafeeqi, T. A., Wood, L. S., Portelli, K., Dunn, J. C. 2023; 39 (1): 172


    Short bowel syndrome (SBS) is a devastating disease. We have proposed spring-mediated distraction enterogenesis for intestinal lengthening. Colonic lengthening is a potential treatment option for SBS to enhance fluid absorption capacity. We hypothesized that intraluminal spring-mediated colonic lengthening is associated with stem cell proliferation.C57BL/6 mice underwent placement of a gelatin-encapsulated compressed or uncompressed nitinol spring in a cecal segment. Animals were given clear liquid diet until postoperative day (POD) 7, followed by regular diet until POD 14. Cecal lengths were measured at euthanasia, and tissue was formalin fixed for histological processing. For Lgr5-GFP mice, immunohistochemistry against GFP was performed to localize Lgr5+ cells within crypts.Significant cecal lengthening with compressed springs and shortening with uncompressed springs were observed on POD 7 and 14. Mucosa of the compressed spring group was significantly thicker on POD 14. The density of Lgr5+ cells within the crypts in the compressed spring groups was higher than that in the uncompressed spring groups on both POD 7 and 14.Expandable springs can be used to lengthen the colon in the mouse model. Colonic lengthening was associated with gradual mucosal thickening and correlated with an increased density of stem cells within the crypts.

    View details for DOI 10.1007/s00383-023-05455-5

    View details for PubMedID 37031428

    View details for PubMedCentralID 5011360

  • Intestinal lengthening via mechanical enterogenesis in an infant with short gut syndrome JOURNAL OF PEDIATRIC SURGERY CASE REPORTS Anderson, T. N., Mueller, C., Dunn, J. Y. 2023; 91
  • Importance of Ileum and Colon in Children with Short Bowel Syndrome. Journal of pediatric surgery Smith, A., Namjoshi, S., Kerner, J. A., Dunn, J. C. 2023


    BACKGROUND: It is well known that small bowel length is a dominant prognostic indicator in patients with short bowel syndrome (SBS). The relative importance of jejunum, ileum, and colon is less well defined in children with SBS. Here we review the outcome of children with SBS with respect to the type of remnant intestine.METHODS: A retrospective review of 51 children with SBS was conducted at a single institution. The duration of parenteral nutrition use was the main outcome variable. The length of the remaining intestine as well as the type of intestine were recorded for each patient. Kaplan-Meier analyses were conducted to compare the subgroups.RESULTS: Children with greater than 10% expected small bowel length or more than 30cm of small bowel achieved enteral autonomy faster than those with less. The presence of ileocecal valve enhanced the ability to wean from parenteral nutrition. The presence of ileum significantly enhanced the ability to wean from parenteral nutrition. Patients with the entire colon also achieved enteral autonomy sooner than those with partial colon.CONCLUSIONS: The preservation of ileum and colon is important in patients with SBS. Approaches to preserve or lengthen ileum and colon may be beneficial for these patients.LEVEL OF EVIDENCE: IV.

    View details for DOI 10.1016/j.jpedsurg.2023.01.053

    View details for PubMedID 36894441

  • Engineered Living Intestinal Muscle Patch Produces Macroscopic Contractions that can Mix and Break down Artificial Intestinal Contents. Advanced materials (Deerfield Beach, Fla.) Wang, Q., Wang, J., Tokhtaeva, E., Li, Z., Martín, M. G., Ling, X. B., Dunn, J. C. 2023: e2207255


    The intestinal muscle layers execute various gut wall movements to achieve controlled propulsion and mixing of intestinal content. Engineering intestinal muscle layers with complex contractile function is critical for developing bioartificial intestinal tissue to treat patients with short bowel syndrome. Here we report the first demonstration of a living intestinal muscle patch capable of generating three distinct motility patterns and displaying multiple digesta manipulations. Assessment of cell contractility, cellular morphology, and transcriptome profile reveals that successful generation of the contracting intestinal muscle patch relies on both biological factors in a serum-free medium and environmental cues from an elastic electrospun gelatin scaffold. By comparing gene-expression patterns among samples, we show that biological factors from the medium strongly affect ion transport activities, while the scaffold unexpectedly regulates cell-cell communication. Analysis of the ligand-receptor interactome identifies the scaffold-driven changes in intercellular communication, and 78% of the upregulated ligand-receptor interactions are involved in the development and function of enteric neurons. Our discoveries highlight the importance of combining biomolecular and biomaterial approaches for tissue engineering. The living intestinal muscle patch represents a pivotal advancement for building functional replacement intestinal tissue. It offers a more physiological model for studying GI motility and for preclinical drug discovery. This article is protected by copyright. All rights reserved.

    View details for DOI 10.1002/adma.202207255

    View details for PubMedID 36779454

  • The effect of spring diameter on porcine ileal distraction enterogenesis. Pediatric surgery international Salimi-Jazi, F., Thomas, A. L., Rafeeqi, T., Diyaolu, M., Wood, L. S., Dunn, J. C. 2022; 39 (1): 19


    Spring-mediated distraction enterogenesis has proven to be successful for intestinal lengthening. We aimed to evaluate the effect of spring diameter mismatch on intestinal adaptation.Juvenile mini-Yucatan pigs underwent placement of compressed nitinol springs with diameter of 10, 11, or 12 mm into the ileal lumen. Pigs were euthanized on postoperative day 7. The lengths, histology, total area of blood vessels, and enteric ganglia were evaluated.All spring groups exhibited significant ileal lengthening. Across the different diameters, spring-expanded segments were similar in terms of ileal lengthening, crypt height, muscular thickness, blood vessels, and enteric ganglia area.Spring-mediated distraction enterogenesis is successful in the porcine ileum. A smaller diameter spring is as effective as a larger diameter spring in lengthening the ileum. Springs of varying diameters result in comparable structural changes in the ileum.

    View details for DOI 10.1007/s00383-022-05300-1

    View details for PubMedID 36449179

    View details for PubMedCentralID 6042758

  • A Novel Role for Biomechanical Forces in the Pathogenesis of Idiopathic Constipation Olutoye, O. O., Lafreniere, A., Short, W. D., Padon, B. W., Li, H., Hsu, B., Dunn, J. Y., Goldstein, A. M., Keswani, S. G., Cheng, L. LIPPINCOTT WILLIAMS & WILKINS. 2022: S172
  • Mechanical Distraction Enterogenesis Using Springs Has Equal Effectiveness in Adult and Juvenile Pigs Rafeeqi, T., Thomas, A., Jazi, F., Diyaolu, M., Dunn, J. Y. LIPPINCOTT WILLIAMS & WILKINS. 2022: S182
  • Stem Cell Activation During Distraction Enterogenesis in Murine Colon Jazi, F., Thomas, A. A., Wood, L., Rafeeqi, T., Portelli, K., Dunn, J. Y. LIPPINCOTT WILLIAMS & WILKINS. 2022: S191
  • Butyrate induces development-dependent necrotizing enterocolitis-like intestinal epithelial injury via necroptosis. Pediatric research Wang, K., Tao, G., Salimi-Jazi, F., Lin, P., Sun, Z., Liu, B., Sinclair, T., Mostaghimi, M., Dunn, J., Sylvester, K. G. 2022


    BACKGROUND: The accumulation of short-chain fatty acids (SCFAs) from bacterial fermentation may adversely affect the under-developed gut as observed in premature newborns at risk for necrotizing enterocolitis (NEC). This study explores the mechanism by which specific SCFA fermentation products may injure the premature newborn intestine mucosa leading to NEC-like intestinal cell injury.METHODS: Intraluminal injections of sodium butyrate were administered to 14- and 28-day-old mice, whose small intestine and stool were harvested for analysis. Human intestinal epithelial stem cells (hIESCs) and differentiated enterocytes from preterm and term infants were treated with sodium butyrate at varying concentrations. Necrosulfonamide (NSA) and necrostatin-1 (Nec-1) were used to determine the protective effects of necroptosis inhibitors on butyrate-induced cell injury.RESULTS: The more severe intestinal epithelial injury was observed in younger mice upon exposure to butyrate (p=0.02). Enterocytes from preterm newborns demonstrated a significant increase in sensitivity to butyrate-induced cell injury compared to term newborn enterocytes (p=0.068, hIESCs; p=0.038, differentiated cells). NSA and Nec-1 significantly inhibited the cell death induced by butyrate.CONCLUSIONS: Butyrate induces developmental stage-dependent intestinal injury that resembles NEC. A primary mechanism of cell injury in NEC is necroptosis. Necroptosis inhibition may represent a potential preventive or therapeutic strategy for NEC.IMPACT: Butyrate induces developmental stage-dependent intestinal injury that resembles NEC. A primary mechanism of cell injury caused by butyrate in NEC is necroptosis. Necroptosis inhibitors proved effective at significantly ameliorating the enteral toxicity of butyrate and thereby suggest a novel mechanism and approach to the prevention and treatment of NEC in premature newborns.

    View details for DOI 10.1038/s41390-022-02333-z

    View details for PubMedID 36202969

  • Long-term safety of intraluminal spring-mediated bowel lengthening. Journal of pediatric surgery Rafeeqi, T., Sullins, V. F., Thomas, A., Wagner, J. P., Wood, L. S., Salimi-Jazi, F., Bessette, A., Dunn, J. C. 2022


    PURPOSE: The purpose of the study is to examine the long-term safety of an endoluminal bowel lengthening device prior to its use in the first human trial. In addition, device performance and natural passage will be evaluated.METHODS: Endoluminal lengthening springs were surgically placed into the jejunum of Yucatan minipigs using the Eclipse XL1 device. A matching internal control segment of jejunum was marked at the time of operation. Weekly weights and fluoroscopic studies were obtained to evaluate spring deployment and position until devices passed. Animals were euthanized at 28, 60, 90, and 180 days. At necropsy, length measurements were recorded, and histopathologic analysis was performed.RESULTS: There were no bowel obstructions or overt perforations attributable to the device. All surviving animals gained weight and were clinically thriving. All devices passed out of the rectum by 180 days. Bowel lengthening was seen in all experimental segments, and minimal fibrosis was observed by 180 days.CONCLUSION: Jejunal lengthening persisted after device had passed through the intestinal tract after 180 days. Early histopathologic changes of the jejunum during distraction enterogenesis normalized over time.

    View details for DOI 10.1016/j.jpedsurg.2022.09.034

    View details for PubMedID 36280466

  • Soluble Protein Hydrolysate Ameliorates Gastrointestinal Inflammation and Injury in 2,4,6-Trinitrobenzene Sulfonic Acid-Induced Colitis in Mice. Biomolecules Wei, J., Tao, G., Xu, B., Wang, K., Liu, J., Chen, C., Dunn, J. C., Currie, C., Framroze, B., Sylvester, K. G. 2022; 12 (9)


    Inflammatory bowel diseases (IBD) are chronic, recurring gastrointestinal diseases that severely impair health and quality of life. Although therapeutic options have significantly expanded in recent years, there is no effective therapy for a complete and permanent cure for IBD. Well tolerated dietary interventions to improve gastrointestinal health in IBD would be a welcome advance especially with anticipated favorable tolerability and affordability. Soluble protein hydrolysate (SPH) is produced by the enzymatic hydrolysis of commercial food industry salmon offcuts (consisting of the head, backbone and skin) and contains a multitude of bioactive peptides including those with anti-oxidant properties. This study aimed to investigate whether SPH ameliorates gastrointestinal injury in 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced mouse colitis model. Mice were randomly assigned to four groups: Control (no colitis), Colitis, Colitis/CP (with control peptide treatment), and Colitis/SPH (with SPH treatment). Colitis was induced by cutaneous sensitization with 1% TNBS on day -8 followed by 2.5% TNBS enema challenge on day 0. Control peptides and SPH were provided to the mice in the Colitis/CP or Colitis/SPH group respectively by drinking water at the final concentration of 2% w/v daily from day -10 to day 4. Then, the colon was harvested on day 4 and examined macro- and microscopically. Relevant measures included disease activity index (DAI), colon histology injury, immune cells infiltration, pro- and anti-inflammatory cytokines and anti-oxidative gene expression. It was found that SPH treatment decreased the DAI score and colon tissue injury when compared to the colitis-only and CP groups. The protective mechanisms of SPH were associated with reduced infiltration of CD4+ T, CD8+ T and B220+ B lymphocytes but not macrophages, downregulated pro-inflammatory cytokines (tumor necrosis factor-alpha and interleukin-6), and upregulated anti-inflammatory cytokines (transforming growth factor-beta1 and interleukin-10) in the colon tissue. Moreover, the upregulation of anti-oxidative genes, including ferritin heavy chain 1, heme oxygenase 1, NAD(P)H quinone oxidoreductase 1, and superoxide dismutase 1, in the colons of colitis/SPH group was observed compared with the control peptide treatment group. In conclusion, the protective mechanism of SPH is associated with anti-inflammatory and anti-oxidative effects as demonstrated herein in an established mice model of colitis. Clinical studies with SPH as a potential functional food for the prevention or as an adjuvant therapy in IBD may add an effective and targeted diet-based approach to IBD management in the future.

    View details for DOI 10.3390/biom12091287

    View details for PubMedID 36139127

  • Generation of Porcine Ileum Through Spring-Mediated Mechanical Distraction. The Journal of surgical research Rafeeqi, T. A., Diyaolu, M., Thomas, A., Salimi-Jazi, F., Wood, L. S., Dunn, J. C. 2022; 280: 371-378


    INTRODUCTION: Short bowel syndrome is a devastating gastrointestinal disorder in which decreased bowel length results in inadequate absorption causing nutritional deficiencies. Current treatment options are accompanied by significant morbidity. We have proposed spring-mediated distraction enterogenesis as a method to lengthen bowel with success seen in porcine jejunum. We hypothesize that spring-mediated distraction enterogenesis can be demonstrated in porcine ileum with preservation of ileal structure and function.MATERIALS AND METHODS: Laparotomy was performed on juvenile female mini-Yucatan pigs and a gelatin-encapsulated compressed nitinol spring was inserted into the ileal lumen and affixed proximally and distally. A control segment distal to the spring segment was marked with sutures. Postoperatively, pigs were placed on a liquid diet and euthanized on postoperative day 7. Spring and control segments were measured and processed for immunohistochemistry to evaluate for the presence of vitamin B12-intrinsic factor cotransporter, chromogranin A-producing cells, and 5-HT producing cells.RESULTS: All seven pigs survived to postoperative day 7 with no adverse effects. On average, pigs gained 84.3±66.4g/d. Spring segments lengthened 1.5±0.7cm with a relative lengthening by 128%±56%, which was statistically significant when compared to control (P<0.01). The average density of chromogranin-A cells in control compared to spring segments was not significantly changed (2.9±1.1cells/mm versus 3.2±1.2cells/mm, P=0.17). Both vitamin B12-intrinsic factor cotransporter and 5-HT producing cells were present in both control and lengthened ileum.CONCLUSIONS: Intraluminal nitinol springs significantly lengthened porcine ileum. The increase in density of enteroendocrine cells may indicate enhanced endocrine function of the lengthened ileum.

    View details for DOI 10.1016/j.jss.2022.07.043

    View details for PubMedID 36037614

  • Surgical Treatment of Short Bowel Syndrome-The Past, the Present and the Future, a Descriptive Review of the Literature. Children (Basel, Switzerland) Muff, J. L., Sokolovski, F., Walsh-Korb, Z., Choudhury, R. A., Dunn, J. C., Holland-Cunz, S. G., Vuille-Dit-Bille, R. N. 2022; 9 (7)


    Short bowel syndrome (SBS) is a devastating disorder with both short- and long-term implications for patients. Unfortunately, the prevalence of SBS has doubled over the past 40 years. Broadly speaking, the etiology of SBS can be categorized as congenital or secondary, the latter typically due to extensive small bowel resection following diseases of the small intestine, e.g., necrotizing enterocolitis, Hirschsprung's disease or intestinal atresia. As of yet, no cure exists, thus, conservative treatment, primarily parenteral nutrition (PN), is the first-line therapy. In some cases, weaning from PN is not possible and operative therapy is required. The invention of the longitudinal intestinal lengthening and tailoring (LILT or Bianchi) procedure in 1980 was a major step forward in patient care and spawned further techniques that continue to improve lives for patients with severe SBS (e.g., double barrel enteroplasty, serial transverse enteroplasty, etc.). With this review, we aim to provide an overview of the clinical implications of SBS, common conservative therapies and the development of operative techniques over the past six decades. We also provide a short outlook on the future of operative techniques, specifically with respect to regenerative medicine.

    View details for DOI 10.3390/children9071024

    View details for PubMedID 35884008

  • Gastrointestinal Myoelectric Measurements via Simultaneous External and Internal Electrodes in Pigs. The Journal of surgical research Salimi-Jazi, F., Thomas, A. L., Rafeeqi, T., Diyaolu, M., Wood, L. S., Axelrod, S., Navalgund, A., Axelrod, L., Dunn, J. C. 2022; 279: 119-126


    Currently, there is no accurate noninvasive measurement system to diagnose gastrointestinal (GI) motility disorders. Wireless skin patches have been introduced to provide an accurate noninvasive measurement of GI myoelectric activity which is essential for developing neuro-stimulation devices to treat GI motility disorders. The aim of this study is to compare the external and internal electrical signal measurements in ambulatory pigs.Yucatan pigs underwent placement of internal electrodes on the stomach, small intestine, and colon. Wires were brought through the abdominal wall. Signals were collected by a wireless receptor. Four external patches were placed on the abdominal skin to record the signals simultaneously. Pigs were kept for 6 d while the sensors were continuously recording the data from both systems.Internal sensors detected rich signals from each organ. The stomach had a dominant frequency that ranged from 4 to 4.5 cpm, with occasional higher frequencies at 2, 3 and 4 times that. Small intestine signals had their primary energy in the 12-15 cpm range. Colon signals primarily displayed a dominant broad peak in the 4-6 cpm region. External skin patches detected a substantial fraction of the activities measured by the internal electrodes. A clear congruence in the frequency spectrum was observed between the internal and external readings.Internally measured myoelectrical signals confirmed different patterns of rhythmic activity of the stomach, small intestine, and colon. Skin patches provided GI myoelectric measurement with a range of frequencies that could be useful in the diagnosis and treatment of motility disorders.

    View details for DOI 10.1016/j.jss.2022.05.012

    View details for PubMedID 35759929

  • A tissue-like neurotransmitter sensor for the brain and gut. Nature Li, J., Liu, Y., Yuan, L., Zhang, B., Bishop, E. S., Wang, K., Tang, J., Zheng, Y., Xu, W., Niu, S., Beker, L., Li, T. L., Chen, G., Diyaolu, M., Thomas, A., Mottini, V., Tok, J. B., Dunn, J. C., Cui, B., Pașca, S. P., Cui, Y., Habtezion, A., Chen, X., Bao, Z. 2022; 606 (7912): 94-101


    Neurotransmitters play essential roles in regulating neural circuit dynamics both in the central nervous system as well as at the peripheral, including the gastrointestinal tract1-3. Their real-time monitoring will offer critical information for understanding neural function and diagnosing disease1-3. However, bioelectronic tools to monitor the dynamics of neurotransmitters in vivo, especially in the enteric nervous systems, are underdeveloped. This is mainly owing to the limited availability of biosensing tools that are capable of examining soft, complex and actively moving organs. Here we introduce a tissue-mimicking, stretchable, neurochemical biological interface termed NeuroString, which is prepared by laser patterning of a metal-complexed polyimide into an interconnected graphene/nanoparticle network embedded in an elastomer. NeuroString sensors allow chronic in vivo real-time, multichannel and multiplexed monoamine sensing in the brain of behaving mouse, as well as measuring serotonin dynamics in the gut without undesired stimulations and perturbing peristaltic movements. The described elastic and conformable biosensing interface has broad potential for studying the impact of neurotransmitters on gut microbes, brain-gut communication and may ultimately be extended to biomolecular sensing in other soft organs across the body.

    View details for DOI 10.1038/s41586-022-04615-2

    View details for PubMedID 35650358

  • The novel application of an emerging device for salvage of primary repair in high-risk complex esophageal atresia. Journal of pediatric surgery Evans, L. L., Chen, C. S., Muensterer, O. J., Sahlabadi, M., Lovvorn, H. N., Novotny, N. M., Upperman, J. S., Martinez, J. A., Bruzoni, M., Dunn, J. C., Harrison, M. R., Fuchs, J. R., Zamora, I. J. 2022


    Preservation of native esophagus is a tenet of esophageal atresia (EA) repair. However, techniques for delayed primary anastomosis are severely limited for surgically and medically complex patients at high-risk for operative repair. We report our initial experience with the novel application of the Connect-EA, an esophageal magnetic compression anastomosis device, for salvage of primary repair in 2 high-risk complex EA patients. Compassionate use was approved by the FDA and treating institutions.Two approaches using the Connect-EA are described - a totally endoscopic approach and a novel hybrid operative approach. To our knowledge, this is the first successful use of a hybrid operative approach with an esophageal magnetic compression device.Salvage of delayed primary anastomosis was successful in both patients. The totally endoscopic approach significantly reduced operative time and avoided repeat high-risk operation. The hybrid operative approach salvaged delayed primary anastomosis and avoided cervical esophagostomy.The Connect-EA is a novel intervention to achieve delayed primary esophageal repair in complex EA patients with high-risk tissue characteristics and multi-system comorbidities that limit operative repair. We propose a clinical algorithm for use of the totally endoscopic approach and hybrid operative approach for use of the Connect-EA in high-risk complex EA patients.

    View details for DOI 10.1016/j.jpedsurg.2022.05.018

    View details for PubMedID 35760639

  • Allometric Tissue-Scale Forces Activate Mechanoresponsive Immune Cells To Drive Pathological Foreign Body Response To Biomedical Implants Padmanabhan, J., Chen, K., Sivaraj, D., Kuehlmann, B., Bonham, C., Dohi, T., Henn, D., Stern-Buchbinder, Z., Than, P., Hosseini, H., Barrera, J., Kussie, H., Magbual, N., Borrelli, M., Trotsyuk, A. A., Kwon, S., Dunn, J., Maan, Z., Januszyk, M., Prantl, L., Gurtner, G. C. WILEY. 2022: A19-A20
  • Metabolic model of necrotizing enterocolitis in the premature newborn gut resulting from enteric dysbiosis. Frontiers in pediatrics Casaburi, G., Wei, J., Kazi, S., Liu, J., Wang, K., Tao, G., Lin, P., Dunn, J. C., Henrick, B. M., Frese, S. A., Sylvester, K. G. 2022; 10: 893059


    Necrotizing enterocolitis (NEC) is a leading cause of premature newborn morbidity and mortality. The clinical features of NEC consistently include prematurity, gut dysbiosis and enteral inflammation, yet the pathogenesis remains obscure. Herein we combine metagenomics and targeted metabolomics, with functional in vivo and in vitro assessment, to define a novel molecular mechanism of NEC. One thousand six hundred and forty seven publicly available metagenomics datasets were analyzed (NEC = 245; healthy = 1,402) using artificial intelligence methodologies. Targeted metabolomic profiling was used to quantify the concentration of specified fecal metabolites at NEC onset (n = 8), during recovery (n = 6), and in age matched controls (n = 10). Toxicity assays of discovered metabolites were performed in vivo in mice and in vitro using human intestinal epithelial cells. Metagenomic and targeted metabolomic analyses revealed significant differences in pyruvate fermentation pathways and associated intermediates. Notably, the short chain fatty acid formate was elevated in the stool of NEC patients at disease onset (P = 0.005) dissipated during recovery (P = 0.02) and positively correlated with degree of intestinal injury (r 2 = 0.86). In vitro, formate caused enterocyte cytotoxicity in human cells through necroptosis (P < 0.01). In vivo, luminal formate caused significant dose and development dependent NEC-like injury in newborn mice. Enterobacter cloacae and Klebsiella pneumoniae were the most discriminatory taxa related to NEC dysbiosis and increased formate production. Together, these data suggest a novel biochemical mechanism of NEC through the microbial production of formate. Clinical efforts to prevent NEC should focus on reducing the functional consequences of newborn gut dysbiosis associated metabolic pathways.

    View details for DOI 10.3389/fped.2022.893059

    View details for PubMedID 36081629

  • Internal plication for spring confinement to lengthen intestine in a porcine model. PloS one Rafeeqi, T. A., Thomas, A., Salimi-Jazi, F., Diyaolu, M., Dunn, J. C. 2022; 17 (9): e0274612


    BACKGROUND: Short bowel syndrome and its resultant nutritional deficiencies are the most common cause of intestinal failure. Significant intestinal lengthening using intraluminal springs is feasible in porcine models using an external plication technique. We hypothesize that an internal plication technique will yield significant intestinal lengthening, which may lead to future endoscopic spring placement.METHODS: Uncompressed springs measuring 7.5 cm with a diameter of 1.0 cm were compressed to 2.0 cm. A gelatin-encapsulated compressed nitinol spring was inserted into the jejunal lumen of juvenile pigs and held in place with endoluminal sutures just proximal and distal to the spring-containing segment. A control segment distal to the spring was marked. Pigs were euthanized on postoperative day 7. Spring and control segments were collected for analyses.RESULTS: There was an average lengthening by 72% of the spring segment compared to the control segment. Two out of 7 springs stayed within both sets of plications and doubled in length. Histology showed normal mucosal integrity of the spring segment and plicated areas with similar muscular thickness but increased crypt depth and villus length compared to the control segment.CONCLUSION: Internal plication resulted in significant bowel lengthening. Five springs had slipped through proximal, distal or both sets of plications, resulting in less lengthening than those that remained fixed. A more consistent methodology for endoluminal suturing is needed to produce more lengthening.

    View details for DOI 10.1371/journal.pone.0274612

    View details for PubMedID 36107915

  • Distraction enterogenesis in the murine colon. Journal of pediatric surgery Portelli, K. I., Thomas, A., Wood, L. S., Diyaolu, M., Taylor, J. S., Dunn, J. C. 2021


    BACKGROUND/PURPOSE: Distraction enterogenesis with intraluminal spring technology has been successfully used to lengthen segments of murine small intestine. We hypothesized that biocompatible springs could also be used to lengthen murine large intestine.METHODS: Age and weight matched C57BL/6 mice underwent surgical insertion of nitinol spring-loaded capsules into the cecum. Segment lengths were measured at initial spring placement and at euthanasia after 7 and 14 days. Histologic adaptations were evaluated at scarification.RESULTS: Cecal segments loaded with compressed springs lengthened an average of 150%, which was significantly longer than control segments loaded with either empty capsules or uncompressed springs. Muscularis layers tended to be thicker in the compressed spring groups compared to control groups.CONCLUSIONS: Insertion of a compressed nitinol spring into the cecum results in significant colonic lengthening in a mouse model. The ability to increase cecum length serves as proof of concept that distraction enterogenesis technology may be feasibly applied to large intestinal models. The use of distraction enterogenesis technology shows promise for application to clinical models in the treatment of pediatric intestinal disease.

    View details for DOI 10.1016/j.jpedsurg.2021.10.005

    View details for PubMedID 34740442

  • Initial Laparotomy Versus Peritoneal Drainage in Extremely Low Birthweight Infants With Surgical Necrotizing Enterocolitis or Isolated Intestinal Perforation: A Multicenter Randomized Clinical Trial. Annals of surgery Blakely, M. L., Tyson, J. E., Lally, K. P., Hintz, S. R., Eggleston, B., Stevenson, D. K., Besner, G. E., Das, A., Ohls, R. K., Truog, W. E., Nelin, L. D., Poindexter, B. B., Pedroza, C., Walsh, M. C., Stoll, B. J., Geller, R., Kennedy, K. A., Dimmitt, R. A., Carlo, W. A., Cotten, C. M., Laptook, A. R., Van Meurs, K. P., Calkins, K. L., Sokol, G. M., Sanchez, P. J., Wyckoff, M. H., Patel, R. M., Frantz, I. D., Shankaran, S., D'Angio, C. T., Yoder, B. A., Bell, E. F., Watterberg, K. L., Martin, C. A., Harmon, C. M., Rice, H., Kurkchubasche, A. G., Sylvester, K., Dunn, J. C., Markel, T. A., Diesen, D. L., Bhatia, A. M., Flake, A., Chwals, W. J., Brown, R., Bass, K. D., St Peter, S. D., Shanti, C. M., Pegoli, W. J., Skarda, D., Shilyansky, J., Lemon, D. G., Mosquera, R. A., Peralta-Carcelen, M., Goldstein, R. F., Vohr, B. R., Purdy, I. B., Hines, A. C., Maitre, N. L., Heyne, R. J., DeMauro, S. B., McGowan, E. C., Yolton, K., Kilbride, H. W., Natarajan, G., Yost, K., Winter, S., Colaizy, T. T., Laughon, M. M., Lakshminrusimha, S., Higgins, R. D., Eunice Kennedy Shriver National Institute of Child Health, H. D. 2021; 274 (4): e370-e380


    OBJECTIVE: The aim of this study was to determine which initial surgical treatment results in the lowest rate of death or neurodevelopmental impairment (NDI) in premature infants with necrotizing enterocolitis (NEC) or isolated intestinal perforation (IP).SUMMARY BACKGROUND DATA: The impact of initial laparotomy versus peritoneal drainage for NEC or IP on the rate of death or NDI in extremely low birth weight infants is unknown.METHODS: We conducted the largest feasible randomized trial in 20 US centers, comparing initial laparotomy versus peritoneal drainage. The primary outcome was a composite of death or NDI at 18 to 22 months corrected age, analyzed using prespecified frequentist and Bayesian approaches.RESULTS: Of 992 eligible infants, 310 were randomized and 96% had primary outcome assessed. Death or NDI occurred in 69% of infants in the laparotomy group versus 70% with drainage [adjusted relative risk (aRR) 1.0; 95% confidence interval (CI): 0.87-1.14]. A preplanned analysis identified an interaction between preoperative diagnosis and treatment group (P = 0.03). With a preoperative diagnosis of NEC, death or NDI occurred in 69% after laparotomy versus 85% with drainage (aRR 0.81; 95% CI: 0.64-1.04). The Bayesian posterior probability that laparotomy was beneficial (risk difference <0) for a preoperative diagnosis of NEC was 97%. For preoperative diagnosis of IP, death or NDI occurred in 69% after laparotomy versus 63% with drainage (aRR, 1.11; 95% CI: 0.95-1.31); Bayesian probability of benefit with laparotomy = 18%.CONCLUSIONS: There was no overall difference in death or NDI rates at 18 to 22 months corrected age between initial laparotomy versus drainage. However, the preoperative diagnosis of NEC or IP modified the impact of initial treatment.

    View details for DOI 10.1097/SLA.0000000000005099

    View details for PubMedID 34506326

  • Mechanical lengthening of porcine small intestine with decreased forces. Journal of pediatric surgery Wood, L. S., Hosseini, H. S., Diyaolu, M., Thomas, A., Taylor, J. S., Dunn, J. C. 2021


    INTRODUCTION: short bowel syndrome is marked by inadequate intestinal surface area to absorb nutrients. Current treatments are focused on medical management and surgical reconfiguration of the dilated intestine. We propose the use of spring-mediated distraction enterogenesis as a novel intervention to increase intestinal length. Given our previous success lengthening intestinal segments using springs with spring constant ~7N/m that exerts 0.46N or higher, we sought to determine the minimal force needed to lengthen porcine small intestinal segments, and to explore effects on intestine over time.METHODS: Juvenile Yucatan pigs underwent laparotomy with enterotomy to introduce nitinol springs intraluminally (n=21 springs). Bowel segments (control, spring-distracted) were retrieved on post-operative day (POD) 7 and 14, and lengths measured. Thickness of cross-sectional intestinal layers were measured using H&E, and submucosal collagen fiber orientation measured using trichrome stained sections.RESULTS: all pigs survived to POD7 and 14. Spring constants of at least 2N/m exerting a minimum force of 0.10N significantly lengthened intestinal segments (p<0.0001). The stronger the spring force, the greater the induced thickness of various intestinal layers at POD7 and 14. Collagen fiber orientation was also more disordered because of stronger springs.CONCLUSION: a spring constant of approximately 2N/m exerting 0.10N and greater significantly lengthens intestinal segments and stimulates intestinal structural changes at POD7 and 14. This suggests a decreased force is capable of inducing spring-mediated distraction enterogenesis.

    View details for DOI 10.1016/j.jpedsurg.2021.03.036

    View details for PubMedID 33836847

  • Biomechanical Force Prediction for Lengthening of Small Intestine during Distraction Enterogenesis. Bioengineering (Basel, Switzerland) Hosseini, H. S., Dunn, J. C. 2020; 7 (4)


    Distraction enterogenesis has been extensively studied as a potential treatment for short bowel syndrome, which is the most common form of intestinal failure. Different strategies including parenteral nutrition and surgical lengthening to manage patients with short bowel syndrome are associated with high complication rates. More recently, self-expanding springs have been used to lengthen the small intestine using an intraluminal axial mechanical force, where this biomechanical force stimulates the growth and elongation of the small intestine. Differences in physical characteristics of patients with short bowel syndrome would require a different mechanical force-this is crucial in order to achieve an efficient and safe lengthening outcome. In this study, we aimed to predict the required mechanical force for each potential intestinal size. Based on our previous experimental observations and computational findings, we integrated our experimental measurements of patient biometrics along with mechanical characterization of the soft tissue into our numerical simulations to develop a series of computational models. These computational models can predict the required mechanical force for any potential patient where this can be advantageous in predicting an individual's tissue response to spring-mediated distraction enterogenesis and can be used toward a safe delivery of the mechanical force.

    View details for DOI 10.3390/bioengineering7040140

    View details for PubMedID 33171760

  • Irreversible Electroporation for De-epithelialization of Murine Small Intestine. The Journal of surgical research Wood, L. S., Dunn, J. C. 2020; 256: 602–10


    BACKGROUND: Nonthermal irreversible electroporation (NTIRE) has been shown to ablate the small intestinal epithelium while maintaining submucosal and muscularis propriae integrity. NTIRE is used here in a first-in-mouse study to eliminate the native intestinal stem cell population to understand optimal parameters and timeline of mucosal regeneration.METHODS: Adult C57 background mice underwent laparotomy and electroporation of 1.5cm of jejunum using a BTX 830 ECM electroporator and electrode calipers. Parameters were varied by voltage, pulse number, interval, and duration to determine optimal de-epithelialization. Electroporated segments were extracted 1 to 3d after intervention with same-animal control segment. Cross sections were preserved, and measurements were taken to compare effects of parameters on villi height, crypt depth, crypt obliteration, and serosal thickness.RESULTS: Morbidity was limited at a standard set of electroporation parameters (14%), and increased with higher voltage, longer interval, and shorter or longer pulses. Serosa/muscularis thickness was unaffected by varying interventions. Crypt depth and obliterated crypts were most affected by modulating pulse number, intervals, and duration. Villi height was most significantly shortened by altering pulse duration, with limited recovery by day 3, otherwise mucosal regeneration was observed in most cases by this point.CONCLUSIONS: NTIRE is an effective method of denuding small intestinal epithelium in mice and temporarily ablating crypts while sparing the support scaffold for native regeneration. This first-in-mouse study of electroporation suggests it is a practical tool that can be utilized in a small mammalian system.

    View details for DOI 10.1016/j.jss.2020.07.034

    View details for PubMedID 32810659

  • Intestinal adaptation following spring insertion into a roux limb in mice. Journal of pediatric surgery Portelli, K. I., Park, J., Taylor, J. S., Thomas, A., Stelzner, M., Martin, M. G., Dunn, J. C. 2020


    BACKGROUND/PURPOSE: Intraluminal springs have recently been shown to lengthen segments of intestine in a process known as distraction enterogenesis. We hypothesized that biocompatible springs could be used to lengthen defunctionalized murine small intestine and would lead to identifiable intestinal adaptations at the molecular level.METHODS: Age and weight matched C57BL/6 mice underwent surgical insertion of nitinol spring-loaded capsules into a Roux limb of jejunum. Segment lengths were measured at initial spring placement and at euthanasia after 14 and 21 days. Histology and gene expression of the Roux limb were evaluated at scarification and compared to untreated control segments.RESULTS: Intestinal segments loaded with compressed springs lengthened an average of 240%, which was significantly longer than control segments loaded with either empty capsules or uncompressed springs. Muscularis thickening was greater in spring-treated mice compared to controls without springs. Crypt depth and Lgr5+ expression was greater in mice that received compressed spring treatments when compared to control groups.CONCLUSIONS: Insertion of a compressed nitinol spring into a Roux limb results in significant intestinal lengthening, smooth muscle thickening, and Lgr5+ expression in a mouse model. The ability to increase small bowel length in a defunctionalized murine model may be used to understand the mechanism of distraction enterogenesis.

    View details for DOI 10.1016/j.jpedsurg.2020.06.033

    View details for PubMedID 32709529

  • Regional Colonic Motility Response to Colon Tissue, Celiac vagus and Sacral Nerve Electrical Stimulation Larauche, M., Wang, Y., Wang, P., Dubrovsky, G., Chen, Y., Dunn, J., Tache, Y., Liu, W., Mulugeta, M. WILEY. 2020
  • Tumescent Injections in Subcutaneous Pig Tissue Disperse Fluids Volumetrically and Maintain Elevated Local Concentrations of Additives for Several Hours, Suggesting a Treatment for Drug Resistant Wounds. Pharmaceutical research Koulakis, J. P., Rouch, J., Huynh, N., Wu, H. H., Dunn, J. C., Putterman, S. 2020; 37 (3): 51


    PURPOSE: Bolus injection of fluid into subcutaneous tissue results in accumulation of fluid at the injection site. The fluid does not form a pool. Rather, the injection pressure forces the interstitial matrix to expand to accommodate the excess fluid in its volume, and the fluid becomes bound similar to that in a hydrogel. We seek to understand the properties and dynamics of externally tumesced (swollen) subcutaneous tissue as a first step in assessing whether tumescent antibiotic injections into wounds may provide a novel method of treatment.METHODS: Subcutaneous injections of saline are performed in live and dead pigs and the physical properties (volume, expansion ratio, residence time, apparent diffusion constant) of the resulting fluid deposits are observed with diffusion-weighted magnetic resonance imaging, computed tomography, and 3D scanning.RESULTS: Subcutaneous tissue can expand to a few times its initial volume to accommodate the injected fluid, which is dispersed thoroughly throughout the tumescent volume. The fluid spreads to peripheral unexpanded regions over the course of a few minutes, after which it remains in place for several hours. Eventually the circulation absorbs the excess fluid and the tissue returns to its original state.CONCLUSIONS: Given the evidence for dense fluid dispersal and several-hour residence time, a procedure is proposed whereby tumescent antibiotic injections are used to treat drug-resistant skin infections and chronic wounds that extend into the subcutaneous tissue. The procedure has the potential to effectively treat otherwise untreatable wounds by keeping drug concentrations above minimum inhibitory levels for extended lengths of time.

    View details for DOI 10.1007/s11095-020-2769-2

    View details for PubMedID 32043171

  • Electroacupuncture to Increase Neuronal Stem Cell Growth MEDICAL ACUPUNCTURE Dubrovsky, G., Ha, D., Thomas, A., Zhu, M., Hubacher, J., Itoh, T., Dunn, J. Y. 2020; 32 (1): 16–23
  • Mesenteric neovascularization during spring-mediated intestinal lengthening. Journal of pediatric surgery Diyaolu, M. n., Thomas, A. L., Wood, L. S., Taylor, J. n., Dunn, J. C. 2020


    Short gut syndrome, a condition characterized by inadequate absorption of nutrients owing to decreased bowel length, has minimal avenues for treatment. We have proposed spring-mediated distraction enterogenesis to lengthen bowel in porcine jejunum as a treatment for short gut. We aim to evaluate the extent of mesenteric neovascularization in segments of lengthened bowel via spring-mediated enterogenesis.Female juvenile Yucatan pigs underwent laparotomy and insertion of gelatin-encapsulated compressed nitinol springs, held in place with plication sutures, into the jejunum. At surgery and sacrifice, macroscopic mesenteric blood vessels were counted between the plication sites. Histologic samples of the mesentery were obtained to evaluate microscopic vasculature.A statistically significant increase in macroscopic mesenteric blood vessels was seen after intestinal lengthening (before: 1.9 ± 0.7 vessels, after: 4.7 ± 1.2 vessels, p = 0.001). A statistical significance is also seen in the density of arterioles (control: 3.0 ± 3.0 vessels/mm, spring: 7.0 ± 9.0 vessels/mm, p = 0.01) and venules (control: 4.0 ± 3.0 vessels/mm, spring: 8.0 ± 8.0 vessels/mm, p = 0.003).Intestinal segments lengthened by intraluminal springs demonstrated total greater number of macroscopic vessels and microscopic blood vessels per length of mesentery as compared to control. This suggests local changes within the mesentery to recruit blood supply to growing intestine.N/A TYPE OF STUDY: Treatment study.

    View details for DOI 10.1016/j.jpedsurg.2020.09.042

    View details for PubMedID 33143878

  • Human skin-derived precursor cells xenografted in aganglionic bowel. Journal of pediatric surgery Thomas, A. L., Taylor, J. S., Dunn, J. C. 2020


    One in 5000 newborns is diagnosed with Hirschsprung disease each year in the United States. The potential of employing neural crest stem cells to restore the enteric nervous system has been investigated. Skin-derived precursor cells (SKPs) are multipotent progenitor cells that can differentiate into neurons and gliocytes in vitro and generate enteric ganglion-like structures in rodents. Here we examined the behavior of human SKPs (hSKPs) after their transplantation into a large animal model of colonic aganglionosis.Juvenile minipigs underwent a chemical denervation of the colon to establish an aganglionosis model. The hSKPs were generated from human foreskin and were cultured in neuroglial-selective medium. Cells were labeled with a fluorescent dye and were injected into the porcine aganglionic colon. After one week, transplanted hSKPs were assessed by immunofluorescence for markers of multipotency and neuroglial differentiation.In culture, hSKPs expressed nestin and S100b indicative of neuroglial precursors. After xenografting in pigs, hSKPs were identified in the myenteric and submucosal plexuses of the colons. The hSKPs expressed nestin and early neuroglial differentiation markers.Human SKPs transplanted into aganglionic colon demonstrated immunophenotypes of neuroglial progenitors, suggesting their potential use for Hirschsprung disease.

    View details for DOI 10.1016/j.jpedsurg.2020.03.006

    View details for PubMedID 32253016

  • The effect of colonic tissue electrical stimulation and celiac branch of the abdominal vagus nerve neuromodulation on colonic motility in anesthetized pigs. Neurogastroenterology and motility : the official journal of the European Gastrointestinal Motility Society Larauche, M. n., Wang, Y. n., Wang, P. M., Dubrovsky, G. n., Lo, Y. K., Hsiang, E. L., Dunn, J. C., Taché, Y. n., Liu, W. n., Million, M. n. 2020: e13925


    Knowledge on optimal electrical stimulation (ES) modalities and region-specific functional effects of colonic neuromodulation is lacking. We aimed to map the regional colonic motility in response to ES of (a) the colonic tissue and (b) celiac branch of the abdominal vagus nerve (CBVN) in an anesthetized porcine model.In male Yucatan pigs, direct ES (10 Hz, 2 ms, 15 mA) of proximal (pC), transverse (tC), or distal (dC) colon was done using planar flexible multi-electrode array panels and CBVN ES (2 Hz, 0.3-4 ms, 5 mA) using pulse train (PT), continuous (10 min), or square-wave (SW) modalities, with or without afferent nerve block (200 Hz, 0.1 ms, 2 mA). The regional luminal manometric changes were quantified as area under the curve of contractions (AUC) and luminal pressure maps generated. Contractions frequency power spectral analysis was performed. Contraction propagation was assessed using video animation of motility changes.Direct colon ES caused visible local circular (pC, tC) or longitudinal (dC) muscle contractions and increased luminal pressure AUC in pC, tC, and dC (143.0 ± 40.7%, 135.8 ± 59.7%, and 142.0 ± 62%, respectively). The colon displayed prominent phasic pressure frequencies ranging from 1 to 12 cpm. Direct pC and tC ES increased the dominant contraction frequency band (1-6 cpm) power locally. Pulse train CBVN ES (2 Hz, 4 ms, 5 mA) triggered pancolonic contractions, reduced by concurrent afferent block. Colon contractions propagated both orally and aborally in short distances.In anesthetized pigs, the dominant contraction frequency band is 1-6 cpm. Direct colonic ES causes primarily local contractions. The CBVN ES-induced pancolonic contractions involve central neural network.

    View details for DOI 10.1111/nmo.13925

    View details for PubMedID 32578346

  • Comparison of Surgical and Cadaveric Intestine as a Source of Crypt Culture in Humans. Cell transplantation Scott, A., Olack, B., Rouch, J. D., Khalil, H. A., Kokubun, B. A., Lei, N. Y., Wang, J., Solorzano, S., Lewis, M., Dunn, J. C., Stelzner, M. G., Niland, J. C., Martin, M. G. 2020; 29: 963689720903709


    Human small intestinal crypts are the source of intestinal stem cells (ISCs) that are capable of undergoing self-renewal and differentiation to an epithelial layer. The development of methods to expand the ISCs has provided opportunities to model human intestinal epithelial disorders. Human crypt samples are usually obtained from either endoscopic or discarded surgical samples, and are thereby exposed to warm ischemia, which may impair their in vitro growth as three-dimensional culture as spheroids or enteroids. In this study we compared duodenal samples obtained from discarded surgical samples to those isolated from whole-body preserved cadaveric donors to generate in vitro cultures. We also examined the effect of storage solution (phosphate-buffered saline or University of Wisconsin [UW] solution) as well as multiple storage times on crypt isolation and growth in culture. We found that intestinal crypts were successfully isolated from cadaveric tissue stored for up to 144 h post-procurement and also were able to generate enteroids and spheroids in certain media conditions. Surgical samples stored in UW after procurement were sufficiently viable up to 24 h and also allowed the generation of enteroids and spheroids. We conclude that surgical samples stored for up to 24 h post-procurement in UW solution allowed for delayed crypt isolation and viable in vitro cultures. Furthermore, in situ, hypothermic preservation in cadaveric duodenal samples permitted crypt/ISC isolation, and successful culture of spheroids and enteroids from tissues held for up to 6 days post-procurement.

    View details for DOI 10.1177/0963689720903709

    View details for PubMedID 32907378

  • Cutaneous Patches to Monitor Myoelectric Activity of the Gastrointestinal Tract in Postoperative Pediatric Patients PEDIATRIC GASTROENTEROLOGY HEPATOLOGY & NUTRITION Taylor, J. S., de Ruijter, V., Brewster, R., Navalgund, A., Axelrod, L., Axelrod, S., Dunn, J. Y., Wall, J. K. 2019; 22 (6): 518–26
  • Cutaneous Patches to Monitor Myoelectric Activity of the Gastrointestinal Tract in Postoperative Pediatric Patients. Pediatric gastroenterology, hepatology & nutrition Taylor, J. S., de Ruijter, V., Brewster, R., Navalgund, A., Axelrod, L., Axelrod, S., Dunn, J. C., Wall, J. K. 2019; 22 (6): 518-526


    Limited means exist to assess gastrointestinal activity in pediatric patients postoperatively. Recently, myoelectric gastrointestinal activity recorded by cutaneous patches has been shown in adult patients to be predictive of clinical return of gastrointestinal function postoperatively. The aim of this case series is to demonstrate the feasibility of this system in pediatric patients and to correlate myoelectric signals with return of bowel function clinically.Pediatric patients undergoing abdominal surgery were recruited to have wireless patches placed on the abdomen within two hours postoperatively. Myoelectric data were transmitted wirelessly to a mobile device with a user-interface and forwarded to a cloud server where processing algorithms identified episodes of motor activity, quantified their parameters and nominally assigned them to specific gastrointestinal organs based on their frequencies.Three patients (ages 5 months, 4 year, 16 year) were recruited for this study. Multiple patches were placed on the older subjects, while the youngest had a single patch due to space limitations. Rhythmic signals of the stomach, small intestine, and colon could be identified in all three subjects. Patients showed gradual increase in myoelectric intestinal and colonic activity leading up to the first recorded bowel movement.Measuring myoelectric intestinal activity continuously using a wireless patch system is feasible in a wide age range of pediatric patients. The increase in activity over time correlated well with the patients' return of bowel function. More studies are planned to determine if this technology can predict return of bowel function or differentiate between physiologic ileus and pathologic conditions.

    View details for DOI 10.5223/pghn.2019.22.6.518

    View details for PubMedID 31777717

    View details for PubMedCentralID PMC6856497

  • Optimization of In-Continuity Spring-Mediated Intestinal Lengthening. Journal of pediatric surgery Dubrovsky, G., Taylor, J. S., Thomas, A., Shekherdimian, S., Dunn, J. C. 2019


    BACKGROUND: Spring-mediated intestinal lengthening has been studied in numerous animal models to effectively achieve up to a 3-fold increase in length. In this study we are interested in optimizing this method of spring lengthening.METHODS: Juvenile mini-Yucatan pigs underwent laparotomy for spring implantation. Springs were secured by plicating the intestine around the springs. In one set of experiments, varying degrees of plication were compared to determine the necessary narrowing needed to confine the spring. In another set of experiments, dissolvable sutures were used for the plication to allow for spontaneous spring passage postoperatively. Intestinal segments were retrieved and evaluated for lengthening and histological changes.RESULTS: Pigs tolerated their diet advancement to a regular diet postoperatively. 10% plication resulted in a 1.3-fold increase in length, while 50% plication resulted in a 2.7-fold increase in length (p<0.05). At two months postoperatively, the majority of springs had safely passed out of the intestine. All lengthened intestine showed significant growth histologically.CONCLUSIONS: A 50% reduction in lumen diameter achieves optimal spring-mediated intestinal lengthening. Springs can safely pass out of the intestine, thus avoiding a second operation for spring removal. These results may be important in developing future therapies for short bowel syndrome.LEVEL OF EVIDENCE: Level I experimental study.

    View details for DOI 10.1016/j.jpedsurg.2019.09.072

    View details for PubMedID 31676077

  • Autologous Transplantation of Skin-Derived Precursor Cells in a Porcine Model. Journal of pediatric surgery Thomas, A., Taylor, J. S., Huynh, N., Dubrovsky, G., Chadarevian, J., Chen, A., Baker, S., Dunn, J. C. 2019


    BACKGROUND: Hirschprung's disease is characterized by aganglionic bowel and often requires surgical resection. Cell-based therapies have been investigated as potential alternatives to restore functioning neurons. Skin-derived precursor cells (SKPs) differentiate into neural and glial cells in vitro and generate ganglion-like structures in rodents. In this report, we aimed to translate this approach into a large animal model of aganglionosis using autologous transplantation of SKPs.METHODS: Juvenile pigs underwent skin procurement from the shoulder and simultaneous chemical denervation of an isolated colonic segment. Skin cells were cultured in neuroglial-selective medium and labeled with fluorescent dye for later identification. The cultured SKPs were then injected into the aganglionic segments of colon, and the specimens were retrieved within seven days after transplantation. SKPs in vitro and in vivo were assessed with histologic samples for various immunofluorescent markers of multipotency and differentiation. SKPs from the time of harvest were compared to those at the time of injection using PCR.RESULTS: Prior to transplantation, 72% of SKPs stained positive for nestin and S100b, markers of neural and glial precursor cells of neural crest origin, respectively. Markers of differentiated neurons and gliocytes, TUJ1 and GFAP, were detected in 47% of cultured SKPs. After transplantation, SKPs were identified in both myenteric and submucosal plexuses of the treated colon. Nestin co-expression was detected in the SKPs within the aganglionic colon in vivo. Injected SKPs appeared to migrate and express early neuroglial differentiation markers.CONCLUSIONS: Autologous SKPs implanted into aganglionic bowel demonstrated immunophenotypes of neuroglial progenitors. Our results suggest that autologous SKPs may be potentially useful for cell-based therapy for patients with enteric nervous system disorders.TYPE OF STUDY: Basic science.

    View details for DOI 10.1016/j.jpedsurg.2019.09.075

    View details for PubMedID 31704043

  • Biomechanical signaling and collagen fiber reorientation during distraction enterogenesis. Journal of the mechanical behavior of biomedical materials Hosseini, H. S., Wood, L. S., Taylor, J. S., Dubrovsky, G., Portelli, K. I., Thomas, A., Dunn, J. C. 2019; 101: 103425


    Distraction enterogenesis has been extensively studied as a potential treatment for short bowel syndrome, which is the most common subset of intestinal failure. Spring distraction uses an intraluminal axial mechanical force to stimulate the growth and elongation of the small intestine. The tissue close to the distracted intestinal segment may also experience signaling to grow. In this study we examined the effects of distraction enterogenesis at different post-operative days on the thickness of small intestinal layers in the intestine proximal and distal to the distracted segment, as well as how the submucosal collagen fibers were reoriented. It was observed that not only different layers of intestine wall in distracted segment showed thickening due to the applied mechanical force but also adjacent tissues in both distal and proximal directions were impacted significantly where they showed thickening as well. The orientation of collagen fibers in submucosa layer was also significantly impacted due to the mechanical force in both distracted and adjacent tissue. The effect of the applied mechanical force on the main distracted tissue and the radial growth of the adjacent tissue strongly suggest actions of paracrine signaling.

    View details for DOI 10.1016/j.jmbbm.2019.103425

    View details for PubMedID 31541857

  • Biomechanics of small intestine during distraction enterogenesis with an intraluminal spring. Journal of the mechanical behavior of biomedical materials Hosseini, H. S., Taylor, J. S., Wood, L. S., Dunn, J. C. 2019; 101: 103413


    During recent years, distraction enterogenesis has been extensively studied as a treatment for short bowel syndrome, which is the most common cause of intestinal failure. Although different strategies such as parenteral nutrition and surgical lengthening have been used to manage the difficulties that patients with SBS deal with, these treatments are associated with high complication rates. Distraction enterogenesis uses mechanical force to increase the length and stimulate growth of the small intestine. In this study we combine in vivo experiments with computational modeling to explore the biomechanics of spring dependent distraction enterogenesis. We hypothesize that the self-expanding spring provides mechanical force for elastic tissue lengthening and triggers cellular proliferation. The additional growth of the intestine suggests signaling between mechanical stress and tissue response. We developed a computational modeling platform to test the correlation of applied mechanical force and tissue growth. We further validated our computational models with experimental measurements using spring-mediated distraction enterogenesis in a porcine model. This modeling platform can incorporate patient biometrics to estimate an individual's tissue response to spring mediated distraction enterogenesis.

    View details for DOI 10.1016/j.jmbbm.2019.103413

    View details for PubMedID 31518947

  • A Wireless Implantable System for Facilitating Gastrointestinal Motility. Micromachines Wang, P., Dubrovsky, G., Dunn, J. C., Lo, Y., Liu, W. 2019; 10 (8)


    Gastrointestinal (GI) electrical stimulation has been shown in several studies to be a potential treatment option for GI motility disorders. Despite the promising preliminary research progress, however, its clinical applicability and usability are still unknown and limited due to the lack of a miniaturized versatile implantable stimulator supporting the investigation of effective stimulation patterns for facilitating GI dysmotility. In this paper, we present a wireless implantable GI modulation system to fill this technology gap. The system consists of a wireless extraluminal gastrointestinal modulation device (EGMD) performing GI electrical stimulation, and a rendezvous device (RD) and a custom-made graphical user interface (GUI) outside the body to wirelessly power and configure the EGMD to provide the desired stimuli for modulating GI smooth muscle activities. The system prototype was validated in bench-top and in vivo tests. The GI modulation system demonstrated its potential for facilitating intestinal transit in the preliminary in vivo chronic study using porcine models.

    View details for DOI 10.3390/mi10080525

    View details for PubMedID 31395845

  • Intravenous Fish Oil and Serum Fatty Acid Profiles in Pediatric Patients With Intestinal Failure-Associated Liver Disease JOURNAL OF PARENTERAL AND ENTERAL NUTRITION Ong, M. L., Venick, R. S., Shew, S. B., Dunn, J. Y., Reyen, L., Grogan, T., Calkins, K. L. 2019; 43 (6): 717–25

    View details for DOI 10.1002/jpen.1532

    View details for Web of Science ID 000479319600003

  • Long-Term Outcomes in Children With Intestinal Failure-Associated Liver Disease Treated With 6 Months of Intravenous Fish Oil Followed by Resumption of Intravenous Soybean Oil JOURNAL OF PARENTERAL AND ENTERAL NUTRITION Wang, C., Venick, R. S., Shew, S. B., Dunn, J. Y., Reyen, L., Gou, R., Calkins, K. L. 2019; 43 (6): 708–16

    View details for DOI 10.1002/jpen.1463

    View details for Web of Science ID 000479319600002

  • The cellular regulators PTEN and BMI1 help mediate NEUROGENIN-3-induced cell cycle arrest. The Journal of biological chemistry Solorzano-Vargas, R. S., Bjerknes, M., Wu, S. V., Wang, J., Stelzner, M., Dunn, J. C., Dhawan, S., Cheng, H., Georgia, S., Martin, M. G. 2019


    Neurogenin-3 (NEUROG3) is a helix-loop-helix (HLH) transcription factor involved in the production of endocrine cells in the intestine and pancreas of humans and mice. However, the human NEUROG3 loss-of-function phenotype differs subtly from that in mice, but the reason for this difference remains poorly understood. Because NEUROG3 expression precedes exit of the cell cycle and the expression of endocrine cell markers during differentiation, we investigated the effect of lentivirus-mediated overexpression of the human NEUROG3 gene on the cell cycle of BON4 cells and various human non-endocrine cell lines. NEUROG3 overexpression induced a reversible cell cycle exit, whereas expression of a neuronal lineage homolog, NEUROG1, had no such effect. In endocrine lineage cells, the cellular quiescence induced by short-term NEUROG3 expression required cyclin-dependent kinase inhibitor 1A (CDKN1A)/p21 CIP1 expression. Expression of endocrine differentiation markers required sustained NEUROG3 expression in the quiescent, but not in the senescent, state. Inhibition of the phosphatase and tensin homolog (PTEN) pathway reversed quiescence by inducing cyclin-dependent kinase 2 (CDK2) and reducing p21CIP1 and NEUROG3 protein levels in BON4 cells and human enteroids. We discovered that NEUROG3 expression stimulates expression of CDKN2a/p16 INK4aand BMI1 proto-oncogene polycomb ring finger (BMI1), with the latter limiting expression of the former, delaying the onset of CDKN2a/p16 INK4a-driven cellular senescence. Furthermore, NEUROG3 bound to the promoters of both CDKN1a/p21 CIP1 and BMI1 genes, and BMI1 attenuated NEUROG3 binding to the CDKN1a/p21 CIP1 promoter. Our findings reveal how human NEUROG3 integrates inputs from multiple signaling pathways and thereby mediates cell cycle exit at the onset of differentiation.

    View details for DOI 10.1074/jbc.RA119.008926

    View details for PubMedID 31341016

  • Delayed appearance of mature ganglia in an infant with an atypical presentation of total colonic and small bowel aganglionosis: a case report. BMC pediatrics Salimi Jazi, F., Chandler, J. M., Thorson, C. M., Sinclair, T. J., Hazard, F. K., Kerner, J. A., Dutta, S., Dunn, J. C., Chao, S. D. 2019; 19 (1): 93


    BACKGROUND: Total colonic and small bowel aganglionosis (TCSA) occurs in less than 1% of all Hirschsprung's disease patients. Currently, the mainstay of treatment is surgery. However, in patients with TCSA, functional outcomes are often poor. A characteristic transition zone in TCSA can be difficult to identify which may complicate surgery and may often require multiple operations.CASE PRESENTATION: We present the case of a male infant who was diagnosed with biopsy-proven total colonic aganglionosis with extensive small bowel involvement as a neonate. The patient was diverted at one month of age based on leveling biopsies at 10cm from the Ligament of Treitz. At 7months of age, during stoma revision for a prolapsed stoma, intra-operative peristalsis was observed in nearly the entire length of the previously aganglionic bowel, and subsequent biopsies demonstrated the appearance of mature ganglion cells in a previously aganglionic segment.CONCLUSIONS: TCSA remains a major challenge for pediatric surgeons. Our case introduces new controversy to our understanding of aganglionosis. Our observations warrant further research into the possibility of post-natal ganglion maturation and encourage surgeons to consider a more conservative surgical approach.

    View details for PubMedID 30953480

  • Intestinal Electrical Stimulation to Increase the Rate of Peristalsis JOURNAL OF SURGICAL RESEARCH Dubrovsky, G., Lo, Y., Wang, P., Wu, M., Nhan Huynh, Liu, W., Dunn, J. Y. 2019; 236: 153–58
  • Intravenous Fish Oil and Serum Fatty Acid Profiles in Pediatric Patients With Intestinal Failure-Associated Liver Disease. JPEN. Journal of parenteral and enteral nutrition Ong, M. L., Venick, R. S., Shew, S. B., Dunn, J. C., Reyen, L., Grogan, T., Calkins, K. L. 2019


    BACKGROUND: Intravenous fish oil (FO) treats pediatric intestinal failure-associated liver disease (IFALD). There are concerns that a lipid emulsion composed of omega-3 fatty acids will cause an essential fatty acid deficiency (EFAD). This study's objective was to quantify the risk for abnormal fatty acid concentrations in children treated with FO.METHODS: Inclusion criteria for this prospective study were children with intestinal failure. Intravenous soybean oil (SO) was replaced with FO for no longer than 6 months. Serum fatty acids were analyzed using linear and logistic models, and compared with age-based norms to determine the percentage of subjects with low and high concentrations.RESULTS: Subjects (n=17) started receiving FO at a median of 3.6 months (interquartile range 2.4-9.6 months). Over time, alpha-linolenic, linoleic, arachidonic, and Mead acid decreased, whereas docosahexaenoic and eicosapentaenoic acid increased (P<0.001 for all). Triene-tetraene ratios remained unchanged (P=1). Although subjects were 1.8 times more likely to develop a low linoleic acid while receiving FO vs SO (95% CI: 1.4-2.3, P<0.01), there was not a significant risk for low arachidonic acid. Subjects were 1.6 times more likely to develop high docosahexaenoic acid while receiving FO vs SO; however, this was not significant (95% CI: 0.9-2.6, P=0.08).CONCLUSION: In this cohort of parenteral nutrition-dependent children, switching from SO to FO led to a decrease in essential fatty acid concentrations, but an EFAD was not evident. Low and high levels of fatty acids developed. Further investigation is needed to clarify if this is clinically significant.

    View details for PubMedID 30900274

  • Intestinal epithelial replacement by transplantation of cultured murine and human cells into the small intestine. PloS one Khalil, H. A., Hong, S. N., Rouch, J. D., Scott, A. n., Cho, Y. n., Wang, J. n., Lewis, M. S., Martin, M. G., Dunn, J. C., Stelzner, M. G. 2019; 14 (5): e0216326


    Adult intestinal epithelial stem cells are a promising resource for treatment of intestinal epithelial disorders that cause intestinal failure and for intestinal tissue engineering. We developed two different animal models to study the implantation of cultured murine and human intestinal epithelial cells in the less differentiated "spheroid" state and the more differentiated "enteroid" state into the denuded small intestine of mice. Engraftment of donor cells could not be achieved while the recipient intestine remained in continuity. However, we were able to demonstrate successful implantation of murine and human epithelial cells when the graft segment was in a bypassed loop of jejunum. Implantation of donor cells occurred in a random fashion in villus and crypt areas. Engraftment was observed in 75% of recipients for murine and 36% of recipients for human cells. Engrafted spheroid cells differentiated into the full complement of intestinal epithelial cells. These findings demonstrate for the first time successful engraftment into the small bowel which is optimized in a bypassed loop surgical model.

    View details for DOI 10.1371/journal.pone.0216326

    View details for PubMedID 31150401

  • Long-Term Outcomes in Children With Intestinal Failure-Associated Liver Disease Treated With 6 Months of Intravenous Fish Oil Followed by Resumption of Intravenous Soybean Oil. JPEN. Journal of parenteral and enteral nutrition Wang, C., Venick, R. S., Shew, S. B., Dunn, J. C., Reyen, L., Gou, R., Calkins, K. L. 2018


    BACKGROUND: Intravenous soybean oil (SO) is a commonly used lipid emulsion for children with intestinal failure (IF); however, it is associated with IF-associated liver disease (IFALD). Studies have demonstrated that intravenous fish oil (FO) is an effective treatment for IFALD. However, there is a lack of long-term data on children who stop FO and resume SO. This study's objective was to investigate our institution's outcomes for children with IFALD treated with 6months of FO and who then restarted SO.METHODS: Inclusion criteria for FO included children with IFALD. Parenteral nutrition (PN)-dependent children resumed SO after FO and were prospectively followed for 4.5 years or until death, transplant, or PN discontinuation. The primary outcome was the cumulative incidence rate (CIR) for cholestasis after FO.RESULTS: Forty-eight subjects received FO, and conjugated bilirubin decreased over time (-0.22mg/dL/week; 95% confidence interval [CI]: -0.25, -0.19; P< .001). The CIR for cholestasis resolution after 6months of FO was 71% (95% CI: 54%, 82%). Twenty-seven subjects resumed SO and were followed for a median of 16months (range 3-51months). While the CIR for enteral autonomy after 3 years of follow-up was 40% (95% CI: 17%, 26%), the CIR for cholestasis and transplant was 26% (95% CI: 8%, 47%) and 6% (95% CI: 0.3%, 25%), respectively.CONCLUSION: In this study, FO effectively treated cholestasis, and SO resumption was associated with cholestasis redevelopment in nearly one-fourth of subjects. Long-term FO may be warranted to prevent end-stage liver disease.

    View details for PubMedID 30411372

  • Intestinal lengthening via multiple in-continuity springs. Journal of pediatric surgery Dubrovsky, G., Huynh, N., Thomas, A., Shekherdimian, S., Dunn, J. C. 2018


    BACKGROUND: Short bowel syndrome is a debilitating condition with few effective treatments. Spring-mediated distraction enterogenesis can be used to lengthen intestine. The purpose of this study is to determine whether multiple springs in series can safely increase the total amount of lengthening.METHODS: Juvenile mini-Yucatan pigs each received three nitinol springs placed within their jejunum. Plication was used to narrow the intestine around each spring to secure them. Compressed springs were used in the experimental group, while uncompressed springs were used in the control group. The intestine was examined 3 weeks later for lengthening and histologic changes.RESULTS: All pigs tolerated diets postoperatively with continued weight gain, and no dilation or obstruction of the intestine was observed. Segments of intestine that contained compressed springs had a significant increase in length from 2.5 cm to 3.9 ± 0.2 cm per spring, compared to segments containing control springs that showed no change (p < 0.001).CONCLUSIONS: Intestinal plication can be safely used to secure multiple springs in series to achieve intestinal lengthening without compromising intestinal function. Using several springs at once allows for a greater amount of total lengthening. This is a promising model that has potential in the treatment of short bowel syndrome.

    View details for PubMedID 30361072

  • Disrupting the LINC complex in smooth muscle cells reduces aortic disease in a mouse model of Hutchinson-Gilford progeria syndrome SCIENCE TRANSLATIONAL MEDICINE Kim, P. H., Luu, J., Heizer, P., Tu, Y., Weston, T. A., Chen, N., Lim, C., Li, R. L., Lin, P., Dunn, J. Y., Hodzic, D., Young, S. G., Fong, L. G. 2018; 10 (460)


    Hutchinson-Gilford progeria syndrome is a disorder of premature aging in children caused by de novo mutations in LMNA that lead to the synthesis of an internally truncated form of prelamin A (commonly called progerin). The production of progerin causes multiple disease phenotypes, including an unusual vascular phenotype characterized by the loss of smooth muscle cells in the arterial media and fibrosis of the adventitia. We show that progerin expression, combined with mechanical stress, promotes smooth muscle cell death. Disrupting the linker of the nucleoskeleton and cytoskeleton (LINC) complex in smooth muscle cells ameliorates the toxic effects of progerin on smooth muscle cells and limits the accompanying adventitial fibrosis.

    View details for PubMedID 30257952

    View details for PubMedCentralID PMC6166472

  • Bioengineering functional smooth muscle with spontaneous rhythmic contraction in vitro SCIENTIFIC REPORTS Kobayashi, M., Khalil, H. A., Lei, N., Wang, Q., Wang, K., Wu, B. M., Dunn, J. Y. 2018; 8: 13544


    Oriented smooth muscle layers in the intestine contract rhythmically due to the action of interstitial cells of Cajal (ICC) that serve as pacemakers of the intestine. Disruption of ICC networks has been reported in various intestinal motility disorders, which limit the quality and expectancy of life. A significant challenge in intestinal smooth muscle engineering is the rapid loss of function in cultured ICC and smooth muscle cells (SMC). Here we demonstrate a novel approach to maintain the function of both ICC and SMC in vitro. Primary intestinal SMC mixtures cultured on feeder cells seeded electrospun poly(3-caprolactone) scaffolds exhibited rhythmic contractions with directionality for over 10 weeks in vitro. The simplicity of this system should allow for wide usage in research on intestinal motility disorders and tissue engineering, and may prove to be a versatile platform for generating other types of functional SMC in vitro.

    View details for PubMedID 30202095

  • Double plication for spring-mediated intestinal lengthening of a defunctionalized Roux limb JOURNAL OF PEDIATRIC SURGERY Dubrovsky, G., Nhan Huynh, Thomas, A., Shekherdimian, S., Dunn, J. Y. 2018; 53 (9): 1806–10


    Spring-mediated distraction enterogenesis has been shown to increase the length of an intestinal segment. The goal of this study is to use suture plication to confine a spring within an intestinal segment while maintaining luminal patency to the rest of the intestine.Juvenile mini-Yucatan pigs underwent placement of nitinol springs within a defunctionalized Roux limb of jejunum. A 20 French catheter was passed temporarily, and sutures were used to plicate the intestinal wall around the catheter at both ends of the encapsulated spring. Uncompressed springs placed in plicated segments and springs placed in nonplicated segments served as controls. The intestine was examined approximately 3 weeks after spring placement.In the absence of plication, springs passed through the intestine within a week. Double plication allowed the spring to stay within the Roux limb for 3 weeks. Compared to uncompressed springs that showed no change in the length of plicated segments, compressed springs caused a significant 1.7-fold increase in the length of plicated segments.Intestinal plication is an effective method to confine endoluminal springs. The confined springs could lengthen intestine that maintains luminal patency. This approach may be useful to lengthen intestine in patients with short bowel syndrome.Level I Experimental Study.

    View details for PubMedID 29352575

  • Fluid flow in tumescent subcutaneous tissue observed with 3D scanning: massage accelerates injection dispersal BIOMEDICAL PHYSICS & ENGINEERING EXPRESS Koulakis, J. P., Dubrovsky, G., Huynh, N., Rouch, J., Dunn, J., Putterman, S. 2018; 4 (4)
  • Mechanisms for intestinal regeneration CURRENT OPINION IN PEDIATRICS Dubrovsky, G., Dunn, J. Y. 2018; 30 (3): 424–29


    The purpose of this review is to briefly summarize the notable structures and pathways in intestinal epithelial growth before presenting the current main areas of active research in intestinal regeneration. As a rapidly advancing field, a number of breakthroughs have recently been made related to the culture of intestinal stem cells (ISCs) and to the engineering of intestinal tissue.ISCs can be derived from fibroblasts and can be cultured in hydrogels under xenogeneic-free conditions. Intestinal organoids can be cultured with neural crest cells to form small intestinal tissues with neuromuscular networks. Endoluminal devices can be placed inside the native intestine to exert mechanical force to induce novel tissue growth.A number of recent advances in the field of intestinal regeneration are encouraging and suggest that novel therapies for a wide range of intestinal disorders may be developed in the near future. There are still a number of obstacles before such stem cell therapies can be safely used in humans.

    View details for PubMedID 29538044

  • Mechanically induced development and maturation of human intestinal organoids in vivo. Nature biomedical engineering Poling, H. M., Wu, D., Brown, N., Baker, M., Hausfeld, T. A., Huynh, N., Chaffron, S., Dunn, J. C., Hogan, S. P., Wells, J. M., Helmrath, M. A., Mahe, M. M. 2018; 2 (6): 429-442


    The natural ability of stem cells to self-organize into functional tissue has been harnessed for the production of functional human intestinal organoids. Although dynamic mechanical forces play a central role in intestinal development and morphogenesis, conventional methods for the generation of intestinal organoids have relied solely on biological factors. Here, we show that the incorporation of uniaxial strain, by using compressed nitinol springs, in human intestinal organoids transplanted into the mesentery of mice induces growth and maturation of the organoids. Assessment of morphometric parameters, transcriptome profiling, and functional assays of the strain-exposed tissue revealed higher similarities to native human intestine, with regards to tissue size and complexity, and muscle tone. Our findings suggest that the incorporation of physiologically relevant mechanical cues during the development of human intestinal tissue enhances its maturation and enterogenesis.

    View details for DOI 10.1038/s41551-018-0243-9

    View details for PubMedID 30151330

    View details for PubMedCentralID PMC6108544

  • Mechanically induced development and maturation of human intestinal organoids in vivo NATURE BIOMEDICAL ENGINEERING Poling, H. M., Wu, D., Brown, N., Baker, M., Hausfeld, T. A., Huynh, N., Chaffron, S., Dunn, J. Y., Hogan, S. P., Wells, J. M., Helmrath, M. A., Mahe, M. M. 2018; 2 (6): 429–42
  • Bioengineered intestinal muscularis complexes with long-term spontaneous and periodic contractions PLOS ONE Wang, Q., Wang, K., Solorzano-Vargas, R., Lin, P., Walthers, C. M., Thomas, A., Martin, M. G., Dunn, J. Y. 2018; 13 (5): e0195315


    Although critical for studies of gut motility and intestinal regeneration, the in vitro culture of intestinal muscularis with peristaltic function remains a significant challenge. Periodic contractions of intestinal muscularis result from the coordinated activity of smooth muscle cells (SMC), the enteric nervous system (ENS), and interstitial cells of Cajal (ICC). Reproducing this activity requires the preservation of all these cells in one system. Here we report the first serum-free culture methodology that consistently maintains spontaneous and periodic contractions of murine and human intestinal muscularis cells for months. In this system, SMC expressed the mature marker myosin heavy chain, and multipolar/dipolar ICC, uniaxonal/multipolar neurons and glial cells were present. Furthermore, drugs affecting neural signals, ICC or SMC altered the contractions. Combining this method with scaffolds, contracting cell sheets were formed with organized architecture. With the addition of intestinal epithelial cells, this platform enabled up to 11 types of cells from mucosa, muscularis and serosa to coexist and epithelial cells were stretched by the contracting muscularis cells. The method constitutes a powerful tool for mechanistic studies of gut motility disorders and the functional regeneration of the engineered intestine.

    View details for PubMedID 29718926

  • Subcutaneous cefazolin to reduce surgical site infections in a porcine model JOURNAL OF SURGICAL RESEARCH Dubrovsky, G., Huynh, N., Rouch, J. D., Koulakis, J. P., Nicolau, D. P., Sutherland, C. A., Putterman, S., Dunn, J. Y. 2018; 224: 156–59


    Surgical site infections (SSIs) pose a significant health and financial burden. A key aspect of appropriate prophylaxis is the administration of antibiotics intravenously (IV). However, subcutaneous administration of antibiotics is not well described in the literature. During surgery, we hypothesize that subcutaneous injection may provide better protection against SSIs. To better understand the kinetics after subcutaneous injection, we describe the serum concentrations of cefazolin in a porcine model.Juvenile mini-Yucatan pigs were administered 20 mL of 25 mg/kg cefazolin subcutaneously, and serial blood samples were taken for 3 h. Blood samples were analyzed for cefazolin concentration using chromatography. Pharmacokinetic data were calculated based on the blood serum concentrations.Maximum serum concentrations of cefazolin were achieved 42.6 ± 2.0 min after the time of injection and were found to be 18.8 ± 7.4 μg/mL. The elimination rate constant was 0.0033 ± 0.0016 min-1 and the half-life was 266 ± 149 min. The area under the curve was 4940 ± 1030 μg × min/mL. The relative bioavailability of subcutaneous injection was 95% +5%/-20%.Subcutaneous administration of cefazolin achieves a significantly lower maximum serum concentration than IV injection. As a result, higher doses of antibiotic can be injected locally without incurring systemic toxicity. Subcutaneous administration will therefore result in higher concentrations of antibiotic for a longer time at the incision site compared with standard IV administration. This strategy of antibiotic delivery may be more effective in preventing SSIs. Further studies are needed to detail the exact effect of subcutaneous antibiotic injection on SSI rates.

    View details for PubMedID 29506833

  • A Wireless Implant for Gastrointestinal Motility Disorders. Micromachines Lo, Y. K., Wang, P. M., Dubrovsky, G., Wu, M. D., Chan, M., Dunn, J. C., Liu, W. 2018; 9 (1)


    Implantable functional electrical stimulation (IFES) has demonstrated its effectiveness as an alternative treatment option for diseases incurable pharmaceutically (e.g., retinal prosthesis, cochlear implant, spinal cord implant for pain relief). However, the development of IFES for gastrointestinal (GI) tract modulation is still limited due to the poorly understood GI neural network (gut⁻brain axis) and the fundamental difference among activating/monitoring smooth muscles, skeletal muscles and neurons. This inevitably imposes different design specifications for GI implants. This paper thus addresses the design requirements for an implant to treat GI dysmotility and presents a miniaturized wireless implant capable of modulating and recording GI motility. This implant incorporates a custom-made system-on-a-chip (SoC) and a heterogeneous system-in-a-package (SiP) for device miniaturization and integration. An in vivo experiment using both rodent and porcine models is further conducted to validate the effectiveness of the implant.

    View details for DOI 10.3390/mi9010017

    View details for PubMedID 30393295

    View details for PubMedCentralID PMC6187657

  • Three-dimensionally printed surface features to anchor endoluminal spring for distraction enterogenesis. PloS one Huynh, N. n., Dubrovsky, G. n., Rouch, J. D., Scott, A. n., Chiang, E. n., Nguyen, T. n., Wu, B. M., Shekherdimian, S. n., Krummel, T. M., Dunn, J. C. 2018; 13 (7): e0200529


    Spring-mediated distraction enterogenesis has been studied as a novel treatment for short bowel syndrome (SBS). Previous approaches are limited by multiple surgeries to restore intestinal continuity. Purely endoluminal devices require a period of intestinal attachment for enterogenesis. The purpose of this study is to modify the device to prevent premature spring migration in a porcine model. Two models were created in juvenile mini-Yucatan pigs for the placement of three-dimensionally printed springs. (1) Two Roux-en-y jejunojenostomies with two Roux limbs were made. A spring with bidirectional hooked surface features was placed in one Roux limb and a spring with smooth surface was placed in the other Roux limb. (2) The in-continuity model had both hooked and smooth surface springs placed directly in intestinal continuity. Spring location was evaluated by weekly radiographs, and the intestine was retrieved after 2 to 4 weeks. Springs with smooth surfaces migrated between 1 to 3 weeks after placement in both porcine models. Springs with bidirectional hooked surface features were anchored to the intestine for up to 4 weeks without migration. Histologically, the jejunal architecture showed significantly increased crypt depth and muscularis thickness compared to normal jejunum. Bidirectional features printed on springs prevented the premature migration of endoluminal springs. These novel spring anchors allowed for their endoluminal placement without any sutures. This approach may lead to the endoscopic placement of the device for patients with SBS.

    View details for PubMedID 30001433

  • A Wireless Implant for Gastrointestinal Motility Disorders MICROMACHINES Lo, Y., Wang, P., Dubrovsky, G., Wu, M., Chan, M., Dunn, J. Y., Liu, W. 2018; 9 (1)

    View details for DOI 10.3390/mi9010017

    View details for Web of Science ID 000424126600017

  • Lgr5 Stem Cell Proliferation from Spring-Mediated Distraction Enterogenesis in a Mouse Model Huynh, N., Dubrovsky, G., Rouch, J. D., Martin, M. G., Dunn, J. C. ELSEVIER SCIENCE INC. 2017: S152–S153
  • Feasibility and scalability of spring parameters in distraction enterogenesis in a murine model JOURNAL OF SURGICAL RESEARCH Nhan Huynh, Dubrovsky, G., Rouch, J. D., Scott, A., Stelzner, M., Shekherdimian, S., Dunn, J. Y. 2017; 215: 219–24


    Distraction enterogenesis has been investigated as a novel treatment for short bowel syndrome (SBS). With variable intestinal sizes, it is critical to determine safe, translatable spring characteristics in differently sized animal models before clinical use. Nitinol springs have been shown to lengthen intestines in rats and pigs. Here, we show spring-mediated intestinal lengthening is scalable and feasible in a murine model.A 10-mm nitinol spring was compressed to 3 mm and placed in a 5-mm intestinal segment isolated from continuity in mice. A noncompressed spring placed in a similar fashion served as a control. Spring parameters were proportionally extrapolated from previous spring parameters to accommodate the smaller size of murine intestines. After 2-3 wk, the intestinal segments were examined for size and histology.Experimental group with spring constants, k = 0.2-1.4 N/m, showed intestinal lengthening from 5.0 ± 0.6 mm to 9.5 ± 0.8 mm (P < 0.0001), whereas control segments lengthened from 5.3 ± 0.5 mm to 6.4 ± 1.0 mm (P < 0.02). Diameter increased similarly in both groups. Isolated segment perforation was noted when k ≥ 0.8 N/m. Histologically, lengthened segments had increased muscularis thickness and crypt depth in comparison to normal intestine.Nitinol springs with k ≤ 0.4 N/m can safely yield nearly 2-fold distraction enterogenesis in length and diameter in a scalable mouse model. Not only does this study derive the safe ranges and translatable spring characteristics in a scalable murine model for patients with short bowel syndrome, it also demonstrates the feasibility of spring-mediated intestinal lengthening in a mouse, which can be used to study underlying mechanisms in the future.

    View details for PubMedID 28688651

  • Spring-Mediated Intestinal Lengthening in a Porcine Model Dubrovsky, G., Nhan Huynh, Rouch, J. D., Scott, A., Thomas, A., Dunn, J. Y., Shekherdimian, S. LIPPINCOTT WILLIAMS & WILKINS. 2017: S29–S30
  • Feasibility and Scalability of Spring Parameters in Distraction Enterogenesis in a Murine Model Nhan Huynh, Dubrovsky, G., Rouch, J. D., Scott, A., Stelzner, M., Shekherdimian, S., Dunn, J. Y. LIPPINCOTT WILLIAMS & WILKINS. 2017: S30
  • New insights and interventions for short bowel syndrome. Current pediatrics reports Rouch, J. D., Dunn, J. C. 2017; 5 (1): 1-5


    This review summarizes recent innovations in the treatment of patients with short bowel syndrome.The use of surgical procedures, growth factor stimulation, and bioengineering approaches to increase absorptive surface area of the intestine is examined. While the morphology of the intestine is clearly altered by these interventions, it is less clear that the overall function of the intestine is improved.Continued innovations will likely bring about new therapeutic options for patients with short bowel syndrome. Careful evaluations of the impact of these interventions await controlled clinical trials.

    View details for DOI 10.1007/s40124-017-0119-6

    View details for PubMedID 28367359

  • Spring-mediated distraction enterogenesis in-continuity. Journal of pediatric surgery Huynh, N., Rouch, J. D., Scott, A., Chiang, E., Wu, B. M., Shekherdimian, S., Dunn, J. C. 2016; 51 (12): 1983-1987


    Distraction enterogenesis has been investigated as a novel treatment for patients with short bowel syndrome (SBS) but has been limited by loss of intestinal length during restoration and need for multiple bowel surgeries. The feasibility of in-continuity, spring-mediated intestinal lengthening has yet to be demonstrated.Juvenile mini-Yucatan pigs underwent in-continuity placement of polycaprolactone (PCL) degradable springs within jejunum. Methods used to anchor the spring ends to the intestine included full-thickness sutures and a high-friction surface spring. Spring constant (k) was 6-15N/m. Bowel was examined for length and presence of spring at 1 to 4weeks.Animals tolerated in-continuity lengthening without bowel obstruction for up to 29days. In-continuity jejunum with springs demonstrated intestinal lengthening by 1.47-fold ±0.11. Five springs had detached prematurely, and lengthening could not be assessed. Histologically, in-continuity jejunum showed significantly increased crypt depth and muscularis thickness in comparison to normal jejunum.Self-expanding endoluminal springs placed in continuity could lengthen intestine without obstruction in a porcine model. This is the first study showing safety and efficacy of a self-expanding endoluminal device for distraction enterogenesis. This is proof-of-concept that in-continuity spring lengthening is feasible and demonstrates its therapeutic potential in SBS.Level 3.

    View details for DOI 10.1016/j.jpedsurg.2016.09.024

    View details for PubMedID 27692863

  • Scalability of an endoluminal spring for distraction enterogenesis. Journal of pediatric surgery Rouch, J. D., Huynh, N., Scott, A., Chiang, E., Wu, B. M., Shekherdimian, S., Dunn, J. C. 2016; 51 (12): 1988-1992


    Techniques of distraction enterogenesis have been explored to provide increased intestinal length to treat short bowel syndrome (SBS). Self-expanding, polycaprolactone (PCL) springs have been shown to lengthen bowel in small animal models. Their feasibility in larger animal models is a critical step before clinical use.Juvenile mini-Yucatan pigs underwent jejunal isolation or blind ending Roux-en-y jejunojejunostomy with insertion of either a PCL spring or a sham PCL tube. Extrapolated from our spring characteristics in rodents, proportional increases in spring constant and size were made for porcine intestine.Jejunal segments with 7mm springs with k between 9 and 15N/m demonstrated significantly increased lengthening in isolated segment and Roux-en-y models. Complications were noted in only two animals, both using high spring constant k>17N/m. Histologically, lengthened segments in the isolated and Roux models demonstrated significantly increased muscularis thickness and crypt depth. Restoration of lengthened, isolated segments back into continuity was technically feasible after 6weeks.Self-expanding, endoluminal PCL springs, which exert up to 0.6N force, safely achieve significant intestinal lengthening in a translatable, large-animal model. These spring characteristics may provide a scalable model for the treatment of SBS in children.

    View details for DOI 10.1016/j.jpedsurg.2016.09.023

    View details for PubMedID 27665493

  • Concise Review: The Potential Use of Intestinal Stem Cells to Treat Patients With Intestinal Failure. Stem cells translational medicine Hong, S. N., Dunn, J. C., Stelzner, M., Martín, M. G. 2016


    : Intestinal failure is a rare life-threatening condition that results in the inability to maintain normal growth and hydration status by enteral nutrition alone. Although parenteral nutrition and whole organ allogeneic transplantation have improved the survival of these patients, current therapies are associated with a high risk for morbidity and mortality. Development of methods to propagate adult human intestinal stem cells (ISCs) and pluripotent stem cells raises the possibility of using stem cell-based therapy for patients with monogenic and polygenic forms of intestinal failure. Organoids have demonstrated the capacity to proliferate indefinitely and differentiate into the various cellular lineages of the gut. Genome-editing techniques, including the overexpression of the corrected form of the defective gene, or the use of CRISPR (clustered regularly interspaced short palindromic repeats)/Cas9 to selectively correct the monogenic disease-causing variant within the stem cell, make autologous ISC transplantation a feasible approach. However, numerous techniques still need to be further optimized, including more robust ex vivo ISC expansion, native ISC ablation, and engraftment protocols. Large-animal models can to be used to develop such techniques and protocols and to establish the safety of autologous ISC transplantation because outcomes in such models can be extrapolated more readily to humans.The field of intestinal stem cell biology has exploded over the past 5 years with discoveries related to in vivo and in vitro stem cell identity and function. The goal of this review article is to highlight the potential use of these cells to treat various epithelial disorders of the gut and discuss the various roadblocks that will be encountered in the coming years.

    View details for DOI 10.5966/sctm.2016-0153

    View details for PubMedID 27638919

  • A novel culture system for adult porcine intestinal crypts CELL AND TISSUE RESEARCH Khalil, H. A., Lei, N. Y., Brinkley, G., Scott, A., Wang, J., Kar, U. K., Jabaji, Z. B., Lewis, M., Martin, M. G., Dunn, J. C., Stelzner, M. G. 2016; 365 (1): 123-134


    Porcine models are useful for investigating therapeutic approaches to short bowel syndrome and potentially to intestinal stem cell (ISC) transplantation. Whereas techniques for the culture and genetic manipulation of ISCs from mice and humans are well established, similar methods for porcine stem cells have not been reported. Jejunal crypts were isolated from murine, human, and juvenile and adult porcine small intestine, suspended in Matrigel, and co-cultured with syngeneic intestinal subepithelial myofibroblasts (ISEMFs) or cultured without feeder cells in various culture media. Media containing epidermal growth factor, noggin, and R-spondin 1 (ENR medium) were supplemented with various combinations of Wnt3a- or ISEMF-conditioned medium (CM) and with glycogen synthase kinase 3 inhibitor (GSK3i), and their effects were studied on cultured crypts. Cell lineage differentiation was assessed by immunohistochemistry and quantitative polymerase chain reaction. Cultured porcine cells were serially passaged and transduced with a lentiviral vector. Whereas ENR medium supported murine enteroid growth, it did not sustain porcine crypts beyond 5 days. Supplementation of Wnt3a-CM and GSK3i resulted in the formation of complex porcine enteroids with budding extensions. These enteroids contained a mixture of stem and differentiated cells and were successfully passaged in the presence of GSK3i. Crypts grown in media supplemented with porcine ISEMF-CM formed spheroids that were less well differentiated than enteroids. Enteroids and spheroids were transfected with a lentivirus with high efficiency. Thus, our method maintains juvenile and adult porcine crypt cells long-term in culture. Porcine enteroids and spheroids can be successfully passaged and transduced by using lentiviral vectors.

    View details for DOI 10.1007/s00441-016-2367-0

    View details for Web of Science ID 000378877600011

    View details for PubMedID 26928041

    View details for PubMedCentralID PMC4919165

  • Basic fibroblast growth factor eluting microspheres enhance distraction enterogenesis JOURNAL OF PEDIATRIC SURGERY Rouch, J. D., Scott, A., Jabaji, Z. B., Chiang, E., Wu, B. M., Lee, S. L., Shekherdimian, S., Dunn, J. C. 2016; 51 (6): 960-965


    The purpose of this study was to determine if distraction enterogenesis using self-expanding polycaprolactone (PCL) springs is a potential therapy for short bowel syndrome. Sustained release basic fibroblast growth factor (bFGF) microspheres have been shown to induce angiogenesis and intestinal regeneration in tissue engineered scaffolds. We hypothesized that the provision of bFGF-loaded microspheres would increase angiogenesis and thereby enhance the process of enterogenesis.A 10-mm segment of rodent jejunum was isolated and an encapsulated PCL spring inserted. Blank or bFGF-loaded microspheres were delivered to the segment. After 4weeks, jejunal segments were assessed for lengthening, morphology, quantification of blood vessels, and ganglia.Lengthened intestinal segments receiving bFGF microspheres demonstrated significantly increased microvascular density compared to those with blank microspheres. There were also significantly more submucosal and myenteric ganglia in the segments that received bFGF microspheres. Segments achieved similar lengthening and final muscular thickness in both blank and bFGF groups, but the bFGF microsphere caused a significant increase in luminal diameter of the jejunal segment.Sustained release bFGF microspheres enhanced distraction enterogenesis through improved vascularity. The synergy of growth factors such as bFGF with distraction enterogenesis may yield improved results for the future treatment of patients with short bowel syndrome.

    View details for DOI 10.1016/j.jpedsurg.2016.02.065

    View details for Web of Science ID 000378908600018

    View details for PubMedID 26995517

  • Long-term renewable human intestinal epithelial stem cells as monolayers: A potential for clinical use JOURNAL OF PEDIATRIC SURGERY Scott, A., Rouch, J. D., Jabaji, Z., Khalil, H. A., Solorzano, S., Lewis, M., Martin, M. G., Stelzner, M. G., Dunn, J. C. 2016; 51 (6): 995-1000


    Current culture schema for human intestinal stem cells (hISCs) frequently rely on a 3D culture system using Matrigel™, a laminin-rich matrix derived from murine sarcoma that is not suitable for clinical use. We have developed a novel 2D culture system for the in vitro expansion of hISCs as an intestinal epithelial monolayer without the use of Matrigel.Cadaveric duodenal samples were processed to isolate intestinal crypts from the mucosa. Crypts were cultured on a thin coat of type I collagen or laminin. Intestinal epithelial monolayers were supported with growth factors to promote self-renewal or differentiation of the hISCs. Proliferating monolayers were sub-cultured every 4-5days.Intestinal epithelial monolayers were capable of long-term cell renewal. Less differentiated monolayers expressed high levels of gene marker LGR5, while more differentiated monolayers had higher expressions of CDX2, MUC2, LYZ, DEF5, and CHGA. Furthermore, monolayers were capable of passaging into a 3D culture system to generate spheroids and enteroids.This 2D system is an important step to expand hISCs for further experimental studies and for clinical cell transplantation.1 Experimental.

    View details for DOI 10.1016/j.jpedsurg.2016.02.074

    View details for Web of Science ID 000378908600025

    View details for PubMedID 26995514

    View details for PubMedCentralID PMC4921284

  • Mechanical lengthening in multiple intestinal segments in-series JOURNAL OF PEDIATRIC SURGERY Scott, A., Rouch, J. D., Huynh, N., Chiang, E., Shekherdimian, S., Lee, S. L., Wu, B. M., Dunn, J. C. 2016; 51 (6): 957-959


    Current models of mechanical intestinal lengthening employ a single device in an isolated segment. Here we demonstrate that polycaprolactone (PCL) springs can be deployed in-series to lengthen multiple intestinal segments simultaneously to further increase overall intestinal length.A Roux-en-y jejunojejunostomy with a blind Roux limb was created in the proximal jejunum of rats. Two encapsulated 10-mm PCL springs were placed in-series into the Roux limb and were secured with clips. After 4weeks, the lengthened segments were retrieved for histological analyses.Lengthening two intestinal segments simultaneously was achieved by placing two PCL springs in-series. The total combined length of the lengthened segments in-series was 45±4mm. The two jejunal segments with PCL springs (25±2 and 20±2mm) were significantly longer than control segments without the spring (14±1mm, p<0.05).Spring-mediated lengthening can be achieved using multiple springs placed sequentially. The use of the Roux-en-y surgical model allowed easy insertion of springs in a blind Roux limb and arrange them in-series. Combined with relengthening techniques, we can use these methods to increase the length of small intestine to reach clinical significance.1 Experimental.

    View details for DOI 10.1016/j.jpedsurg.2016.02.058

    View details for Web of Science ID 000378908600017

    View details for PubMedID 27013424

  • Development of Functional Microfold (M) Cells from Intestinal Stem Cells in Primary Human Enteroids PLOS ONE Rouch, J. D., Scott, A., Lei, N. Y., Solorzano-Vargas, R. S., Wang, J., Hanson, E. M., Kobayashi, M., Lewis, M., Stelzner, M. G., Dunn, J. C., Eckmann, L., Martin, M. G. 2016; 11 (1)


    Intestinal microfold (M) cells are specialized epithelial cells that act as gatekeepers of luminal antigens in the intestinal tract. They play a critical role in the intestinal mucosal immune response through transport of viruses, bacteria and other particles and antigens across the epithelium to immune cells within Peyer's patch regions and other mucosal sites. Recent studies in mice have demonstrated that M cells are generated from Lgr5+ intestinal stem cells (ISCs), and that infection with Salmonella enterica serovar Typhimurium increases M cell formation. However, it is not known whether and how these findings apply to primary human small intestinal epithelium propagated in an in vitro setting.Human intestinal crypts were grown as monolayers with growth factors and treated with recombinant RANKL, and assessed for mRNA transcripts, immunofluorescence and uptake of microparticles and S. Typhimurium.Functional M cells were generated by short-term culture of freshly isolated human intestinal crypts in a dose- and time-dependent fashion. RANKL stimulation of the monolayer cultures caused dramatic induction of the M cell-specific markers, SPIB, and Glycoprotein-2 (GP2) in a process primed by canonical WNT signaling. Confocal microscopy demonstrated a pseudopod phenotype of GP2-positive M cells that preferentially take up microparticles. Furthermore, infection of the M cell-enriched cultures with the M cell-tropic enteric pathogen, S. Typhimurium, led to preferential association of the bacteria with M cells, particularly at lower inoculum sizes. Larger inocula caused rapid induction of M cells.Human intestinal crypts containing ISCs can be cultured and differentiate into an epithelial layer with functional M cells with characteristic morphological and functional properties. This study is the first to demonstrate that M cells can be induced to form from primary human intestinal epithelium, and that S. Typhimurium preferentially infect these cells in an in vitro setting. We anticipate that this model can be used to generate large numbers of M cells for further functional studies of these key cells of intestinal immune induction and their impact on controlling enteric pathogens and the intestinal microbiome.

    View details for DOI 10.1371/journal.pone.0148216

    View details for Web of Science ID 000369528400076

    View details for PubMedID 26820624

    View details for PubMedCentralID PMC4731053

  • Mouse model of endoscopically ablated enteric nervous system JOURNAL OF SURGICAL RESEARCH Khalil, H. A., Kobayashi, M., Rana, P., Wagner, J. P., Scott, A., Yoo, J., Dunn, J. C. 2016; 200 (1): 117-121


    Current transgenic animal models of Hirschsprung disease are restricted by limited survival and need for special dietary care. We used small animal colonoscopy to produce chemically ablated enteric nervous system in the distal colon and rectum of normal mice.Adult C57BL/6 mice underwent colonoscopy with submucosal injection of 75-100 μL of saline (n = 2) or 0.002% (n = 2), 0.02% (n = 15), or 0.2% (n = 2) benzalkonium chloride (BAC). Each mouse received 1-3 injections in the distal colon and rectum. Mice were sacrificed on postprocedure day 7 or 28. Injection sites were analyzed histologically and with immunostaining for β-tubulin III.Submucosal injection of 0.02% BAC resulted in megacolon and obliteration of 82 ± 8.8% of myenteric ganglia at the injection site on postprocedure day 7 compared with normal colon. This effect was sustained until day 28. Injection of 0.002% BAC had little effect on the myenteric neuronal network at these time points. Multiple injections of 0.002% or 0.02% BAC (up to three injections per mouse) were well tolerated. Injection of 0.2% BAC caused acute toxicity or death.A novel model of chemically ablated enteric nervous system in the mouse colon and rectum is introduced. This model can be valuable in evaluating targeted cell delivery therapies for Hirschsprung disease.

    View details for DOI 10.1016/j.jss.2015.07.034

    View details for Web of Science ID 000366840700018

    View details for PubMedID 26299595

  • Intestinal Bioengineering. Clinical transplants Dunn, J. C. 2016; 32: 1-4


    This review summarizes bioengineering innovations in the treatment of patients with short bowel syndrome. Bioengineering approaches aim to increase the overall intestinal tissue mass. While the morphology of the intestine is clearly altered by these interventions, it remains to be shown that the overall function of the intestine is improved. Continued innovations will likely bring about new therapeutic options for patients with short bowel syndrome. Careful evaluations of the impact of these interventions await controlled clinical trials.

    View details for PubMedID 28564517

  • A multicenter study to standardize reporting and analyses of fluorescence-activated cell-sorted murine intestinal epithelial cells AMERICAN JOURNAL OF PHYSIOLOGY-GASTROINTESTINAL AND LIVER PHYSIOLOGY Magness, S. T., Puthoff, B. J., Crissey, M. A., Dunn, J., Henning, S. J., Houchen, C., Kaddis, J. S., Kuo, C. J., Li, L., Lynch, J., Martin, M. G., May, R., Niland, J. C., Olack, B., Qian, D., Stelzner, M., Swain, J. R., Wang, F., Wang, J., Wang, X., Yan, K., Yu, J., Wong, M. H. 2013; 305 (8): G542-G551


    Fluorescence-activated cell sorting (FACS) is an essential tool for studies requiring isolation of distinct intestinal epithelial cell populations. Inconsistent or lack of reporting of the critical parameters associated with FACS methodologies has complicated interpretation, comparison, and reproduction of important findings. To address this problem a comprehensive multicenter study was designed to develop guidelines that limit experimental and data reporting variability and provide a foundation for accurate comparison of data between studies. Common methodologies and data reporting protocols for tissue dissociation, cell yield, cell viability, FACS, and postsort purity were established. Seven centers tested the standardized methods by FACS-isolating a specific crypt-based epithelial population (EpCAM+/CD44+) from murine small intestine. Genetic biomarkers for stem/progenitor (Lgr5 and Atoh 1) and differentiated cell lineages (lysozyme, mucin2, chromogranin A, and sucrase isomaltase) were interrogated in target and control populations to assess intra- and intercenter variability. Wilcoxon's rank sum test on gene expression levels showed limited intracenter variability between biological replicates. Principal component analysis demonstrated significant intercenter reproducibility among four centers. Analysis of data collected by standardized cell isolation methods and data reporting requirements readily identified methodological problems, indicating that standard reporting parameters facilitate post hoc error identification. These results indicate that the complexity of FACS isolation of target intestinal epithelial populations can be highly reproducible between biological replicates and different institutions by adherence to common cell isolation methods and FACS gating strategies. This study can be considered a foundation for continued method development and a starting point for investigators that are developing cell isolation expertise to study physiology and pathophysiology of the intestinal epithelium.

    View details for DOI 10.1152/ajpgi.00481.2012

    View details for PubMedID 23928185

  • A nomenclature for intestinal in vitro cultures AMERICAN JOURNAL OF PHYSIOLOGY-GASTROINTESTINAL AND LIVER PHYSIOLOGY Stelzner, M., Helmrath, M., Dunn, J. C., Henning, S. J., Houchen, C. W., Kuo, C., Lynch, J., Li, L., Magness, S. T., Martin, M. G., Wong, M. H., Yu, J. 2012; 302 (12): G1359-G1363


    Many advances have been reported in the long-term culture of intestinal mucosal cells in recent years. A significant number of publications have described new culture media, cell formations, and growth patterns. Furthermore, it is now possible to study, e.g., the capabilities of isolated stem cells or the interactions between stem cells and mesenchyme. However, at the moment there is significant variation in the way these structures are described and named. A standardized nomenclature would benefit the ability to communicate and compare findings from different laboratories using the different culture systems. To address this issue, members of the NIH Intestinal Stem Cell Consortium herein propose a systematic nomenclature for in vitro cultures of the small and large intestine. We begin by describing the structures that are generated by preparative steps. We then define and describe structures produced in vitro, specifically: enterosphere, enteroid, reconstituted intestinal organoid, induced intestinal organoid, colonosphere, colonoid, and colonic organoid.

    View details for DOI 10.1152/ajpgi.00493.2011

    View details for Web of Science ID 000305398600001

    View details for PubMedID 22461030

    View details for PubMedCentralID PMC3378093

  • Risk Factors for Parenteral Nutrition-associated Liver Disease Following Surgical Therapy for Necrotizing Enterocolitis JOURNAL OF PEDIATRIC GASTROENTEROLOGY AND NUTRITION Duro, D., Mitchell, P. D., Kalish, L. A., Martin, C., Mccarthy, M., Jaksic, T., Dunn, J., Brandt, M. L., Nobuhara, K. K., Sylvester, K. G., Moss, R. L., Duggan, C. 2011; 52 (5): 595-600


    The aim of the study was to prospectively determine risk factors for the development of parenteral nutrition-associated liver disease (PNALD) in infants who underwent surgery for necrotizing enterocolitis (NEC), the most common cause of intestinal failure in children.: From February 2004 to February 2007, we diagnosed 464 infants with NEC, of whom 180 had surgery. One hundred twenty-seven patients were available for full analysis. PNALD was defined as serum direct bilirubin ≥ 2 mg/dL or ALT ≥ 2 × the upper limit of normal in the absence of sepsis after ≥ 14 days of exposure to PN.Median gestational age was 26 weeks and 68% were boys. Seventy percent of the cohort developed PNALD and the incidence of PNALD varied significantly across the 6 study sites, ranging from 56% to 85% (P = 0.05). Multivariable logistic regression analysis identified small-bowel resection or creation of jejunostomy (odds ratio [OR] 4.96, 95% confidence interval [CI] 1.97-12.51, P = 0.0007) and duration of PN in weeks (OR 2.37, 95% CI 1.56-3.60, P < 0.0001) as independent risk factors for PNALD. Preoperative exposure to PN was also associated with the development of PNALD; the risk of PNALD was 2.6 (95% CI 1.5-4.7; P = 0.001) times greater in patients with ≥ 4 weeks of preoperative PN compared with those with less preoperative PN use. Breast milk feedings, episodes of infection, and gestational age were not related to the development of PNALD.The incidence of PNALD is high in infants with NEC undergoing surgical treatment. Risk factors for PNALD are related to signs of NEC severity, including the need for small-bowel resection or proximal jejunostomy, as well as longer exposure to PN. Identification of these and other risk factors can help in the design of clinical trials for the prevention and treatment of PNALD and for clinical assessment of patients with NEC and prolonged PN dependence.

    View details for DOI 10.1097/MPG.0b013e31820e8396

    View details for Web of Science ID 000289671900018

    View details for PubMedID 21464752

    View details for PubMedCentralID PMC3444282

  • Risk Factors for Intestinal Failure in Infants with Necrotizing Enterocolitis: A Glaser Pediatric Research Network Study JOURNAL OF PEDIATRICS Duro, D., Kalish, L. A., Johnston, P., Jaksic, T., Mccarthy, M., Martin, C., Dunn, J. C., Brandt, M., Nobuhara, K. K., Sylvester, K. G., Moss, R. L., Duggan, C. 2010; 157 (2): 203-U50


    To determine risk factors for intestinal failure (IF) in infants undergoing surgery for necrotizing enterocolitis (NEC).Infants were enrolled in a multicenter prospective cohort study. IF was defined as the requirement for parenteral nutrition for >or= 90 days. Logistic regression was used to identify predictors of IF.Among 473 patients enrolled, 129 had surgery and had adequate follow-up data, and of these patients, 54 (42%) developed IF. Of the 265 patients who did not require surgery, 6 (2%) developed IF (OR 31.1, 95% CI, 12.9 - 75.1, P < .001). Multivariate analysis identified the following risk factors for IF: use of parenteral antibiotics on the day of NEC diagnosis (OR = 16.61, P = .022); birth weight < 750 grams, (OR = 9.09, P < .001); requirement for mechanical ventilation on the day of NEC diagnosis (OR = 6.16, P = .009); exposure to enteral feeding before NEC diagnosis (OR=4.05, P = .048); and percentage of small bowel resected (OR = 1.85 per 10 percentage point greater resection, P = .031).The incidence of IF among infants undergoing surgical treatment for NEC is high. Variables characteristic of severe NEC (low birth weight, antibiotic use, ventilator use, and greater extent of bowel resection) were associated with the development of IF.

    View details for DOI 10.1016/j.jpeds.2010.02.023

    View details for Web of Science ID 000279871700011

    View details for PubMedID 20447649

    View details for PubMedCentralID PMC3217834