Gillian Fell

All Publications

• Repeated lengthening using distraction enterogenesis: A porcine model. Surgery Emengo, P., Fell, G. L., Nepomuceno, H., Thomas, A. L., Dunn, J. C. 2026; 194: 110159

  Abstract

  Spring-mediated distraction enterogenesis aims to use mechanical stretch to generate new functional intestinal tissue in patients with short bowel syndrome. Because of the incremental nature of spring-mediated distraction enterogenesis, patients may require multiple spring insertions to produce enough tissue to wean off parenteral nutrition. We aim to demonstrate the feasibility of repeated lengthening within the same intestinal segment.Juvenile Yucatan pigs underwent a laparotomy to introduce a gelatin-encapsulated nitinol spring into the jejunum. After 14-21 days, a second laparotomy was performed to remove the initial spring and insert a new compressed spring with a greater force constant into a portion of the previously lengthened jejunum. After 7 days, the pigs were killed, and samples were collected.Spring insertion produced a significant increase in jejunal length when compared to controls. Both the initial and the subsequent stronger springs produced an equivalent amount of lengthening. Crypt depth, mucosal thickness, muscularis thickness, and the outer serosal perimeter of the repeatedly lengthened jejunal segments all increased compared with control segments.Previously lengthened segments of jejunum were successfully relengthened using spring-mediated distraction enterogenesis in a porcine model. This suggests that patients with short bowel syndrome may be offered repeat distraction procedures to achieve a greater increase in bowel length than a single spring-mediated distraction enterogenesis procedure.

  View details for DOI 10.1016/j.surg.2026.110159

  View details for PubMedID 41880743

• A national database study of adjuvant steroids following Kasai portoenterostomy for biliary atresia. Pediatric surgery international Liang, N. E., Thobani, H., Moturu, A., Suh, E., Islam, S., Fell, G. L., Hyun, J. S., Sylvester, K. G., Chao, S. D., Dunn, J. C., Khan, F. A. 2026; 42 (1)

  Abstract

  Adjuvant steroids in the treatment of BA remains controversial. We sought to characterize variations in steroid use and their effect on postoperative outcomes in a multi-institutional cohort of BA patients.PHIS was queried for all patients between 2017 and 2024 who were diagnosed with BA and underwent KPE. Patients who received ≥ 3 contiguous days of steroids within 7 days of KPE were considered to have received postoperative steroids. The primary outcome was native liver survival, calculated using Kaplan-Meier analysis.504 patients from 37 hospitals with a median age of 52 days (IQR: 35-69 days) met inclusion criteria. 139 patients (28.6%) received adjuvant steroids. The steroid-treated cohort had a significantly longer postoperative LOS (P < 0.001) and high-volume-KPE hospitals were significantly more likely to use adjuvant steroids (P < 0.001). The majority of patients were started on steroids on POD#0. 5 hospitals utilized steroids in > 50% of their patients after KPE. Kaplan-Meier analysis showed no difference in two-year native liver survival.In this large multi-institutional cohort study, steroids were used early, with significant intra-hospital variation, and were associated with increased postoperative LOS and higher KPE volume. Larger multi-institutional studies with standardized steroid dosage regimens and extended long-term follow up are needed.III.

  View details for DOI 10.1007/s00383-026-06401-x

  View details for PubMedID 41865321

  View details for PubMedCentralID 4303045

• Epithelial Ion Transport in Spring-Lengthened Jejunum in a Porcine Model. Journal of pediatric surgery Joo, N. S., Thomas, A. L., Salimi-Jazi, F., Rafeeqi, T. A., Fell, G., Emengo, P., Nguyen, J. A., Diyaolu, M., Abazari, S., Sellers, Z. M., Dunn, J. C. 2025: 162880

  Abstract

  Loss of functional small intestine in short bowel syndrome results in profound nutrient malabsorption and diarrhea. We previously developed an expandable spring device that triggers intestinal lengthening. The aim of this study was to assess the functional ion transport capabilities of spring-lengthened jejunum.Mini-Yucatan pigs underwent laparotomy and spring placement in the jejunum. After 7 days, pigs were euthanized to retrieve spring-lengthened and distal control jejunum. Tissues were mounted in Ussing chambers to measure transepithelial resistance and short-circuit current (Isc). Forskolin and carbachol were used to measure cAMP- and calcium-mediated anion secretory capacities, and glucose was used for absorptive capacity. Tissue samples were then preserved for histopathology and immunochemistry.Intestinal segments exposed to springs became longer at euthanasia. Baseline transepithelial resistance and Isc were similar between spring-lengthened and control jejunum. Forskolin, carbachol, and glucose increased Isc above baseline in both lengthened and control jejunum. While glucose-stimulated Isc was similar between lengthened and control jejunum, forskolin- and carbachol-stimulated Isc were reduced. Spring-lengthened jejunum had greater mucosal area with deeper crypts and taller villi, but similar crypt: villus ratios as control jejunum. Spring-lengthened jejunum had thicker muscularis propria compared to controls.Spring-lengthening of small bowel does not disrupt mucosal barrier function, based on histological and functional assessments. While spring-lengthened jejunum showed reduced transepithelial secretory function, its absorptive function appears intact. This change may be related to early tissue remodeling during distraction enterogenesis and further investigation into the cellular changes induced by distraction enterogenesis are ongoing.

  View details for DOI 10.1016/j.jpedsurg.2025.162880

  View details for PubMedID 41423148

• Pediatric metabolic and bariatric surgery: When is the right time to operate? Current problems in pediatric and adolescent health care Shacker, M., Chinn, J., Pratt, J. S., Fell, G. L. 2025: 101882

  Abstract

  Pediatric obesity is a growing epidemic associated with serious long-term health consequences, including diabetes, cardiovascular disease, and reduced life expectancy. Metabolic and bariatric surgery (MBS) is a safe, effective, and durable treatment for adolescents with severe or refractory obesity; however, it remains significantly underutilized. As a consequence, children with severe obesity and associated comorbidities progress to an advanced stage of disease that can be even more challenging to treat than in adults. Current evidence demonstrates that MBS in adolescents achieves comparable or even superior weight loss and comorbidity resolution compared to adults, with favorable long-term safety profiles. In select cases, GLP-1 receptor agonists (GLP-1RAs), may be used as an adjunct to MBS. Current evidence for GLP-1RA use in the preoperative period is limited, although when reinitiated early in the postoperative period, they may be associated with improved weight loss outcomes. Despite strong guideline support, <0.05 % of eligible children undergo MBS, likely due to poor access to adolescent MBS centers, limited insurance coverage, and a lack of awareness or misinformation surrounding MBS, among other causes. Multidisciplinary support including preoperative teaching, mental health services, and long-term postoperative follow-up is essential to the success of the procedure. Further research is needed to better characterize the disparities in access, improve outreach and education efforts, combat the stigma associated with adolescent MBS, and address this growing public health crisis.

  View details for DOI 10.1016/j.cppeds.2025.101882

  View details for PubMedID 41344950

• The impact of social determinants of health on adolescent metabolic and bariatric surgical outcomes. Surgery for obesity and related diseases : official journal of the American Society for Bariatric Surgery Chinn, J. O., Herdes, R. E., Shacker, M., Santos, V., Fell, G. L., Pratt, J. S. 2025

  Abstract

  Prior research has shown higher rates of complications across a broad spectrum of surgeries in pediatric patients with higher Social Vulnerability Index (SVI).This study aims to compare how SVI impacts outcomes in adolescents undergoing metabolic and bariatric surgery (MBS).Academic Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program-adolescent accredited care center METHODS: We performed a retrospective cohort study of 126 adolescents and young adults undergoing laparoscopic sleeve gastrectomy between September 2014 and April 2021. Comparative analysis was performed for demographics, percent total body weight loss (%TBWL), and complications between those with high (≥ .75) and low (<.75) SVI.There were 47 patients in the high SVI group and 79 in the low SVI group. Age at surgery, gender, primary language, and insurance type were similar between groups. Preoperative weight and body mass index (BMI) were higher in the high SVI group compared to the low SVI group (145 kg vs 136 kg, P = .033, BMI 52 vs 46, P < .001). Average distance to the hospital was similar (82 miles in high SVI group vs 100 miles in low SVI group, P = .079). The high SVI group had a trend towards a higher percentage of patients who identified as Hispanic/Latino (64% vs 47%, P = .064) and less patients who identified as white (28% vs 51%, P = .054). There was no significant difference in mean %TBWL at 3 months, 6 months, or 12 months (23% in high SVI group (N = 40) compared to 22% in low SVI group (N = 66), P = .4). Complication rates were low in both groups, with no difference between SVI groups (6.5% vs 5.1%, P = .707). While the number of patients with long-term data decreased over time, there was no difference in %TBWL at 2, 3, or 4 years after surgery.Despite a diverse patient population and significant geographic barriers, the outcomes between high and low SVI in this cohort were comparable. Continued efforts need to be made to expand access to MBS for socioeconomic disadvantaged adolescent patients with obesity.

  View details for DOI 10.1016/j.soard.2025.11.009

  View details for PubMedID 41339175

• Wound Healing and Management Considerations in the Pediatric Surgical Patient. Advances in wound care Liang, N. E., Jing, S. L., Suh, E. J., Wang, H. H., Pham, B. P., Chiu, B., Hyun, J. S., Griffin, M. F., Longaker, M. T., Fell, G. L. 2025

  Abstract

  Significance: Wound healing in pediatric patients is affected by physiology, growth, and development considerations unique from those in adults. In the following report, we review the primary literature on aging and wound healing and highlight clinical wound healing applications for the pediatric patient across age ranges from neonates and infants in the first year of life to adolescents (aged 10-19 years by World Health Organization definition). Recent Advances: We characterize the differences in wound healing biology between infants, adolescents, and adults and discuss wound care strategies for pediatric surgical patients, highlighting evidence-based guidelines for wound management. We discuss relevant animal models and review the multidisciplinary aspects of providing wound care for children. Critical Issues: Pediatric surgical patients have specialized wound care needs. Optimizing wound care outcomes for infants, children, and adolescents relies on an understanding of their wound-healing biology and unique physiological, psychological, and social considerations. Future Directions: Future directions in pediatric wound care will focus on validating and optimizing emerging technologies through pediatric-specific clinical trials, while also addressing key knowledge gaps in topical agent pharmacokinetics and advancing regenerative approaches like mesenchymal stem cell therapies tailored to the unique biology of infants and children.

  View details for DOI 10.1177/21621918251387640

  View details for PubMedID 41192826

• Submucosal Hydrogel for Spring-Mediated Intestinal Lengthening. Journal of biomedical materials research. Part A Salimi-Jazi, F., de Paiva Narciso, N., Fell, G., Thomas, A., Navarro, R. S., Rafeeqi, T., Baugh, N. J., Suhar, R. A., Nguyen, J., Lopez, N., Heilshorn, S. C., Dunn, J. C. 2025; 113 (10): e37986

  Abstract

  Spring-mediated distraction enterogenesis has shown success in intestinal lengthening, with spring confinement achieved by external plication with sutures to reduce the lumen diameter at both ends of the intestinal segment. Endoscopic spring placement would minimize the morbidity associated with device insertion. This study investigates the use of submucosal injection of engineered hydrogel to temporarily confine a compressed spring within an intestinal segment. Engineered hydrogels were composed of hyaluronic acid (HA) alone or HA with elastin-like protein (HELP). To simulate endoscopic injection in six juvenile pigs, hydrogel was injected into the submucosa in everted jejunum, followed by the placement of a gelatin-encapsulated, compressed nitinol spring. The jejunum was then unfolded over the spring, and hydrogel was injected distally into the submucosa. Sutures were placed as fiducial markers. After 7days on a liquid diet, the pigs were euthanized, and their intestinal segments were analyzed for lengthening and histological changes. The spring-containing jejunal segments expanded in all animals, lengthening to 132% in the HA group and 188% in the HELP group. HELP hydrogels exhibited slower biodegradation than HA-only hydrogels. Histological analysis showed increased crypt width and decreased crypt density in the spring-containing segments compared to controls. Hydrogel effectively provides temporary spring confinement within intestinal segments without adverse effects. The mechanical stimulation from the spring induces crypt fission, expanding the intestinal epithelium. These results support the feasibility of gel-enabled, spring-mediated distraction enterogenesis for intestinal lengthening.

  View details for DOI 10.1002/jbm.a.37986

  View details for PubMedID 40977628

• Metabolic and bariatric surgery in adolescents compared to young adults: an MBSAQIP database analysis. Surgery for obesity and related diseases : official journal of the American Society for Bariatric Surgery Shacker, M., Chao, S. D., Chinn, J. O., Fell, G. L., Mueller, C. M., Pratt, J. S. 2025

  Abstract

  Metabolic and bariatric surgery (MBS) is a highly durable, safe and effective treatment for severe obesity in adults. However, MBS remains underutilized in the pediatric and adolescent population, likely due to safety concerns of elective surgery in children.We aimed to analyze whether the benefits of MBS outweigh the risks in adolescents when compared to young adults.Multicenter, national database study.Patients aged 10-39 who underwent Roux-en-Y gastric bypass (RYGB) or sleeve gastrectomy (SG). Patients with prior foregut surgery were excluded.556,628 patients were identified; 10,883 (2.0%) were aged 10-19 (adolescents), 161,938 (29.1%) were 20-29 (young adults), and 383,807 (69.0%) were 30-39 (adults). Preoperative body mass index (BMI) was clinically similar between groups, though statistically significant due to large sample size (10-19: 46, 20-29: 45, 30-39: 45 kg/m2, P < .001). SG was more common in younger cohorts (10-19: 86%, 20-29: 77%, 30-39: 75%, P < .001). At 30 days postoperatively, adolescents demonstrated marginally greater BMI reduction (10-19: 2.91, 20-29: 2.69, 30-39: 2.53 kg/m2, P < .001). Adolescents had fewer postoperative complications, including surgical site infections, gastrointestinal bleeding, and blood transfusions (P < .001). Among adolescents, SG (aOR: .39, CI: .31-.48, P < .001) was associated with reduced postoperative complications.Adolescents undergoing MBS have BMI reductions similar to those of young adults and have lower rates of complications and readmissions. MBS should be offered as a safe treatment for adolescents to treat morbid obesity with at least similar frequency as it is offered to adults.

  View details for DOI 10.1016/j.soard.2025.08.010

  View details for PubMedID 40946077

• Pediatric Metabolic and Bariatric Surgery and Anti-Obesity Medications: Weighing Efficacy, Risks, and Future Directions. The Journal of pediatrics Chinn, J. O., Baidal, J. W., Pratt, J. S., Shepard, W. E., Fell, G. L. 2025: 114610

  View details for DOI 10.1016/j.jpeds.2025.114610

  View details for PubMedID 40252955

• BA-ECM Score: Automated Quantification of Liver Fibrosis Architecture in Biliary Atresia with Potential for Prognostic Value - A Pilot Study. Annals of surgery Liang, N. E., Guo, J. L., Griffin, M. F., Bauer-Rowe, K. E., Narang, A., Januszyk, M., Fell, G. L., Dunn, J. C., Chao, S. D., Tan, S. Y., Longaker, M. T., Hyun, J. S. 2025

  Abstract

  To quantify liver fibrosis in infants with biliary atresia (BA) through automated analysis of collagen extracellular matrix (ECM) ultrastructure in index liver biopsies and use a composite fibrosis architecture score to predict native liver survival.Despite early management with Kasai portoenterostomy , BA remains the leading indication for pediatric liver transplantation. There is no established method for quantitatively assessing liver fibrosis in patients with BA, and no factors to accurately predict which patients will ultimately require transplantation early versus late.Index liver biopsies from 12 BA patients were retrieved from our pathology archives Masson's Trichrome-stained biopsies were scanned, tiled, binarized, and quantified for 147 ECM features. These features were reduced by Uniform Manifold Approximation and Projection. Pseudotime analysis was applied to summarize global variations in architecture and assign BA-ECM scores to all biopsy images. Retrospective chart review was performed to correlate clinical characteristics with BA-ECM score.BA-ECM score, a multi-dimensional fibrosis architecture score, was significantly higher for biopsies from listed patients compared to non-listed patients (35.9 vs. 22.9, *P<0.0001). High BA-ECM score was characterized by thick, patchy, irregular ECM, while low BA-ECM score was associated with large-volume thin, porous collagen fibers. Survival analysis stratified by the third quartile BA-ECM score of all data points demonstrated a significant difference in native liver survival (*P=0.02).We present the application of an automated ECM ultrastructure analysis tool designed to capture and quantify 147 aspects of fibrotic tissue heterogeneity. These manifold features are summarized using a multi-dimensional BA-ECM score that could be used to prognosticate disease course for BA patients.

  View details for DOI 10.1097/SLA.0000000000006698

  View details for PubMedID 40109267

• Dipeptidylpeptidase 4 Is Overexpressed in the Extracellular Matrix of Biliary Atresia-Associated Liver Fibrosis Liang, N., Griffin, M., Parker, J. B. L., Guo, J. L., Bauer-Rowe, K. E., Fell, G. L., Dunn, J. C. Y., Tan, S. Y. S., Hyun, J. S., Longaker, M. T. LIPPINCOTT WILLIAMS & WILKINS. 2024: S347-S348

  View details for Web of Science ID 001348680702168

• Pediatric metabolic and bariatric surgery: indications and preoperative multidisciplinary evaluation. Surgery for obesity and related diseases : official journal of the American Society for Bariatric Surgery Mangarelli, C., Fell, G., Hobbs, E., Lowry, K. W., Williams, E., Pratt, J. S. 2024

  Abstract

  The standard of care for pediatric patients with severe obesity considering metabolic and bariatric surgery is a preoperative multidisciplinary evaluation. A multidisciplinary team allows for the efficient use of variable personnel expertise to evaluate, manage, and support a pediatric patient and family through metabolic and bariatric surgery. This review discusses the purpose, recommended team members, patient selection, content, and benefits of the multidisciplinary preoperative evaluation. This evaluation should reduce barriers to care and optimize patient safety and outcomes while taking into consideration the unique developmental needs of this age group.

  View details for DOI 10.1016/j.soard.2024.08.025

  View details for PubMedID 39304458

• beta-Endorphin mediates radiation therapy fatigue SCIENCE ADVANCES Hermann, A. L., Fell, G. L., Kemeny, L., Fung, C. Y., Held, K. D., Biggs, P. J., Rivera, P. D., Bilbo, S. D., Igras, V., Willers, H., Kung, J., Gheorghiu, L., Hideghety, K., Mao, J., Woolf, C. J., Fisher, D. E. 2022; 8 (50): eabn6025

  Abstract

  Fatigue is a common adverse effect of external beam radiation therapy in cancer patients. Mechanisms causing radiation fatigue remain unclear, although linkage to skin irradiation has been suggested. β-Endorphin, an endogenous opioid, is synthesized in skin following genotoxic ultraviolet irradiation and acts systemically, producing addiction. Exogenous opiates with the same receptor activity as β-endorphin can cause fatigue. Using rodent models of radiation therapy, exposing tails and sparing vital organs, we tested whether skin-derived β-endorphin contributes to radiation-induced fatigue. Over a 6-week radiation regimen, plasma β-endorphin increased in rats, paralleled by opiate phenotypes (elevated pain thresholds, Straub tail) and fatigue-like behavior, which was reversed in animals treated by the opiate antagonist naloxone. Mechanistically, all these phenotypes were blocked by opiate antagonist treatment and were undetected in either β-endorphin knockout mice or mice lacking keratinocyte p53 expression. These findings implicate skin-derived β-endorphin in systemic effects of radiation therapy. Opioid antagonism may warrant testing in humans as treatment or prevention of radiation-induced fatigue.

  View details for DOI 10.1126/sciadv.abn6025

  View details for Web of Science ID 000917907400012

  View details for PubMedID 36525492

  View details for PubMedCentralID PMC9757747