The Blue Ribbon Committee II Report and Recommendations on Surgical Education and Training in the United States: 2024.

OBJECTIVE: An expert panel made recommendations to optimize surgical education and training based on the effects of contemporary challenges. BACKGROUND: The inaugural Blue Ribbon Committee (BRC I) proposed sweeping recommendations for surgical education and training in 2004. In light of those findings, a second BRC (BRC II) was convened to make recommendations to optimize surgical training considering the current landscape in medical education. METHODS: BRC II was a panel of 67 experts selected on the basis of experience and leadership in surgical education and training. It was organized into subcommittees which met virtually over the course of a year. They developed recommendations, along with the Steering Committee, based on areas of focus and then presented them to the entire BRC II. The Delphi Method was chosen to obtain consensus, defined as>80% agreement amongst the panel. Cronbach alpha was computed to assess the internal consistency of three Delphi rounds. RESULTS: Of 50 recommendations, 31 obtained consensus in the following aspects of surgical training (# consensus recommendation /# proposed): Workforce (1/5), Medical Student Education (3/8), Work Life Integration (4/6), Resident Education (5/7), Goals, Structure and Financing of Training (5/8), Education Support and Faculty Development (5/6), Research Training (7/9), and Educational Technology and Assessment (1/1). The internal consistency was good in Rounds 1 and 2 and acceptable in Round 3. CONCLUSIONS: BRC II used the Delphi approach to identify and recommend 31 priorities for surgical education in 2024. We advise establishing a multidisciplinary surgical educational group to oversee, monitor and facilitate implementation of these recommendations.

Transforming the Future of Surgeon-Scientists.

OBJECTIVE: To create a blueprint for surgical department leaders, academic institutions, and funding agencies to optimally support surgeon-scientists. BACKGROUND: Scientific contributions by surgeons have been transformative across many medical disciplines. Surgeon-scientists provide a distinct approach and mindset toward key scientific questions. However, lack of institutional support, pressure for increased clinical productivity, and growing administrative burden are major challenges for the surgeon-scientist, as is the time-consuming nature of surgical training and practice. METHODS: An American Surgical Association Research Sustainability Task Force was created to outline a blueprint for sustainable science in surgery. Leaders from top NIH-sponsored departments of surgery engaged in video and in-person meetings between January and April 2023. A strength, weakness, opportunities, threats analysis was performed, and workgroups focused on the roles of surgeons, the department and institutions, and funding agencies. RESULTS: Taskforce recommendations: (1) SURGEONS: Growth mindset : identifying research focus, long-term planning, patience/tenacity, team science, collaborations with disparate experts; Skill set : align skills and research, fill critical skill gaps, develop team leadership skills; DEPARTMENT OF SURGERY (DOS): (2) MENTORSHIP: Chair : mentor-mentee matching/regular meetings/accountability, review of junior faculty progress, mentorship training requirement, recognition of mentorship (eg, relative value unit equivalent, awards; Mentor: dedicated time, relevant scientific expertise, extramural funding, experience and/or trained as mentor, trusted advisor; Mentee : enthusiastic/eager, proactive, open to feedback, clear about goals; (3) FINANCIAL SUSTAINABILITY: diversification of research portfolio, identification of matching funding sources, departmental resource awards (eg, T-/P-grants), leveraging of institutional resources, negotiation of formalized/formulaic funds flow investment from academic medical center toward science, philanthropy; (4) STRUCTURAL/STRATEGIC SUPPORT: Structural: grants administrative support, biostats/bioinformatics support, clinical trial and research support, regulatory support, shared departmental laboratory space/equipment; Strategic: hiring diverse surgeon-scientist/scientists faculty across DOS, strategic faculty retention/ recruitment, philanthropy, career development support, progress tracking, grant writing support, DOS-wide research meetings, regular DOS strategic research planning; (5) COMMUNITY AND CULTURE: Community: right mix of faculty, connection surgeon with broad scientific community; Culture: building research infrastructure, financial support for research, projecting importance of research (awards, grand rounds, shoutouts); (6) THE ROLE OF INSTITUTIONS: Foundation: research space co-location, flexible start-up packages, courses/mock study section, awards, diverse institutional mentorship teams; Nurture: institutional infrastructure, funding (eg, endowed chairs), promotion friendly toward surgeon-scientists, surgeon-scientists in institutional leadership positions; Expectations: RVU target relief, salary gap funding, competitive starting salaries, longitudinal salary strategy; (7) THE ROLE OF FUNDING AGENCIES: change surgeon research training paradigm, offer alternate awards to K-awards, increasing salary cap to reflect market reality, time extension for surgeon early-stage investigator status, surgeon representation on study section, focused award strategies for professional societies/foundations. CONCLUSIONS: Authentic recommitment from surgeon leaders with intentional and ambitious actions from institutions, corporations, funders, and society is essential in order to reap the essential benefits of surgeon-scientists toward advancements of science.

Surgical Education.

This paper summarizes the proceedings of the joint European Surgical Association ESA/American Surgical Association symposium on Surgical Education that took place in Bordeaux, France, as part of the celebrations for 30 years of ESA scientific meetings. Three presentations on the use of quantitative metrics to understand technical decisions, coaching during training and beyond, and entrustable professional activities were presented by American Surgical Association members and discussed by ESA members in a symposium attended by members of both associations.

Experience of a single academic institution with the National Accreditation Program for Rectal Cancer and the resulting improvement in care.

AIM: The American College of Surgeons Committee on Cancer developed the National Accreditation Program for Rectal Cancer (NAPRC) to reduce variations in rectal cancer care, standardize clinical practice and encourage multidisciplinary approaches. The aim of this study was to analyse if accreditation achieved a higher quality of care at one hospital. METHOD: The University of California Davis Medical Center was accredited in 2019. A retrospective review of rectal adenocarcinoma patients was performed between the years 2013 and 2018. Patients presenting from 2013 to 2015 were discussed at a gastrointestinal tumour board while patients in 2018 had an accredited rectal cancer tumour board. Patients from 2016 to 2017 were excluded as the programme was still developing. Compliance to the NAPRC standards was compared between the cohorts. RESULTS: One hundred and thirty patients were evaluated, 88 (68%) in the prerectal tumour board cohort and 42 (32%) in the rectal tumour board cohort. The prerectal tumour board cohort often failed to meet attendance standards. All patients in the rectal tumour board cohort met all criteria. Similarly, clinical service compliance improved in the rectal tumour board cohort for 13 metrics, 10 of which were statistically significant. Although a high proportion of patients in both groups experienced quality surgery, i.e. complete total mesorectal excision and negative margins, the lack of complete pathological reporting in the prerectal tumour board cohort limited analysis. CONCLUSION: Multidisciplinary rectal cancer tumour boards are associated with improved compliance with recommended care by the NAPRC. Patients discussed at a rectal cancer tumour board were more likely to receive appropriate staging, coordinated care and have better clinical documentation.

Gender Disparity in Pediatric Surgery: An Evaluation of Pediatric Surgery Conference Participation.

BACKGROUND: Leadership in academic conferences is an important factor for academic advancement. Underrepresentation of women in academic surgical conferences has been demonstrated in other subspecialties, but it has not been well-studied in pediatric surgery. METHODS: This retrospective descriptive study analyzes conference participation at 2 national pediatric surgery annual conference programs from 2003 to 2022. Moderator, speakers, and research presenter sex was collected. The primary outcome was the proportion of female participants in each of these roles. Mann-Kendall trend test was conducted to assess for significance. RESULTS: Across 29 meetings, a total of 523 sessions were examined. Overall, female participation in all roles increased from 2003 to 2022. There were statistically positive trends of female participation in leadership roles as moderator (p = 0.003) and speaker (p = 0.01), with moderator role demonstrating the largest proportional female increase over time - with a 7-fold increase from 7.1% in 2003 to 50.0% in 2022. There was also a significant increasing trend in female participation as research presenters (p < 0.01) from 25.4% to 46.4%. CONCLUSION: Gender representation in pediatric surgery conferences has improved over the last two decades. Women now represent approximately half of all participatory roles, and efforts to continue providing equal opportunities for women at pediatric surgery academic conferences should continue. LEVEL OF EVIDENCE: N/A. TYPE OF STUDY: Retrospective Descriptive.

Evaluation of a biodegradable polyurethane patch for repair of diaphragmatic hernia in a rat model: A pilot study.

INTRODUCTION: Congenital diaphragmatic hernia (CDH) repair is an area of active research. Large defects requiring patches have a hernia recurrence rate of up to 50%. We designed a biodegradable polyurethane (PU)-based elastic patch that matches the mechanical properties of native diaphragm muscle. We compared the PU patch to a non-biodegradable Gore-Tex™ (polytetrafluoroethylene) patch. METHODS: The biodegradable polyurethane was synthesized from polycaprolactone, hexadiisocyanate and putrescine, and then processed into fibrous PU patches by electrospinning. Rats underwent 4 mm diaphragmatic hernia (DH) creation via laparotomy followed by immediate repair with Gore-Tex™ (n = 6) or PU (n = 6) patches. Six rats underwent sham laparotomy without DH creation/repair. Diaphragm function was evaluated by fluoroscopy at 1 and 4 weeks. At 4 weeks, animals underwent gross inspection for recurrence and histologic evaluation for inflammatory reaction to the patch materials. RESULTS: There were no hernia recurrences in either cohort. Gore-Tex™ had limited diaphragm rise compared to sham at 4 weeks (1.3 mm vs 2.9 mm, p = 0.003), but no difference was found between PU and sham (1.7 mm vs 2.9 mm, p = 0.09). There were no differences between PU and Gore-Tex™ at any time point. Both patches formed an inflammatory capsule, with similar thicknesses between cohorts on the abdominal (Gore-Tex™ 0.07 mm vs. PU 0.13 mm, p = 0.39) and thoracic (Gore-Tex™ 0.3 mm vs. PU 0.6 mm, p = 0.09) sides. CONCLUSION: The biodegradable PU patch allowed for similar diaphragmatic excursion compared to control animals. There were similar inflammatory responses to both patches. Further work is needed to evaluate long-term functional outcomes and further optimize the properties of the novel PU patch in vitro and in vivo. LEVEL OF EVIDENCE: Level II, Prospective Comparative Study.

Does the American College of Surgeons New Level I Children's Surgery Center Verification Affect Treatment Efficiency and Narcotic Administration in Treating Pediatric Trauma Patients with Femur Fracture?

BACKGROUND: In 2015, the American College of Surgeons (ACS) created a new hospital improvement program to enhance the performance of pediatric care in US hospitals. The Children's Surgery Verification (CSV) Quality Improvement Program is predicated on the idea that pediatric surgical patients have improved outcomes when treated at children's hospitals with optimal resources. Achieving ACS level I CSV designation at pediatric trauma centers may lead to greater benefits for pediatric trauma patients; however, the specific benefits have yet to be identified. We hypothesize that achieving the additional designation of ACS level I CSV is associated with decreased narcotic use perioperatively and improved efficiency when managing pediatric patients with femur fractures. STUDY DESIGN: This study is a retrospective analysis of traumatic pediatric orthopaedic femur fractures treated at a verified level I pediatric trauma center before and after CSV designation (2010 to 2014 vs 2015 to 2019). Efficiency parameters, defined as time from admission to surgery, duration of surgery, and duration of hospital stay, and narcotic administration in oral morphine equivalents (OMEs) were compared. RESULTS: Of 185 traumatic femur fractures analyzed, 80 occurred before meeting ACS level I CSV criteria, and 105 occurred after. Post-CSV, there was a significant decrease in mean wait time from admission to surgery (16.64 hours pre-CSV, 12.52 hours post-CSV [p < 0.01]) and duration of hospital stay (103.49 hours pre-CSV, 71.61 hours post-CSV [p < 0.01]). Narcotic usage was significantly decreased in both the preoperative period (40.61 OMEs pre-CSV, 23.77 OMEs post-CSV [p < 0.01]) and postoperative period (126.67 OMEs pre-CSV, 45.72 OMEs post-CSV [p < 0.01]). CONCLUSIONS: Achieving ACS level I CSV designation is associated with increased efficiency and decreased preoperative and postoperative narcotic use when treating pediatric trauma patients.

Surgery Clerkship Directors' Perceptions of the COVID-19 Pandemic's Impact on Medical Student Education.

BACKGROUND: This study assessed the national impact of the COVID-19 pandemic on the education of medical students assigned to surgery clerkship rotations, as reported by surgery clerkship directors(CDs). STUDY DESIGN: In the spring of 2020 and 2021, the authors surveyed 164 CDs from 144 LCME-accredited US medical schools regarding their views of the pandemic's impact on the surgery clerkship curriculum, students' experiences, outcomes, and institutional responses. RESULTS: Overall survey response rates, calculated as no. respondents/no. surveyed were 44.5%(73/164) and 50.6%(83/164) for the spring 2020 and 2021 surveys, respectively. Nearly all CDs(>95%) pivoted to virtual platforms and solutions. Most returned to some form of in-person learning by winter 2020, and pre-pandemic status by spring 2021(46%, 38/83). Students' progression to the next year was delayed by 12%(9/73), and preparation was negatively impacted by 45%(37/83). Despite these data, CDs perceived students' interest in surgical careers was not significantly affected(89% vs. 77.0%, p=0.09). Over the one-year study, the proportion of CDs reporting a severe negative impact on the curriculum dropped significantly(p<0.0001) for most parameters assessed except summative evaluations(40.3% vs. 45.7%,p=0.53). CDs(n=83) also noted the pandemic's positive impact with respect to virtual patient encounters(21.7%), didactics(16.9%), student test performance(16.9%), continuous personal learning(14.5%), engagement in the clerkship(9.6%) and student interest in surgery as a career(7.2%). CONCLUSION: During the pandemic, the severe negative impact on student educational programs lessened and novel virtual curricular solutions emerged. Student interest in surgery as a career was sustained. Measures of student competency and effectiveness of new curriculum, including telehealth, remain areas for future investigation.

Engineered extracellular vesicles with high collagen-binding affinity present superior in situ retention and therapeutic efficacy in tissue repair.

Although stem cell-derived extracellular vesicles (EVs) have remarkable therapeutic potential for various diseases, the therapeutic efficacy of EVs is limited due to their degradation and rapid diffusion after administration, hindering their translational applications. Here, we developed a new generation of collagen-binding EVs, by chemically conjugating a collagen-binding peptide SILY to EVs (SILY-EVs), which were designed to bind to collagen in the extracellular matrix (ECM) and form an EV-ECM complex to improve EVs' in situ retention and therapeutic efficacy after transplantation. Methods: SILY was conjugated to the surface of mesenchymal stem/stromal cell (MSC)-derived EVs by using click chemistry to construct SILY-EVs. Nanoparticle tracking analysis (NTA), ExoView analysis, cryogenic electron microscopy (cryo-EM) and western-blot analysis were used to characterize the SILY-EVs. Fluorescence imaging (FLI), MTS assay, ELISA and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) were used to evaluate the collagen binding and biological functions of SILY-EVs in vitro. In a mouse hind limb ischemia model, the in vivo imaging system (IVIS), laser doppler perfusion imaging (LDPI), micro-CT, FLI and RT-qPCR were used to determine the SILY-EV retention, inflammatory response, blood perfusion, gene expression, and tissue regeneration. Results:In vitro, the SILY conjugation significantly enhanced EV adhesion to the collagen surface and did not alter the EVs' biological functions. In the mouse hind limb ischemia model, SILY-EVs presented longer in situ retention, suppressed inflammatory responses, and significantly augmented muscle regeneration and vascularization, compared to the unmodified EVs. Conclusion: With the broad distribution of collagen in various tissues and organs, SILY-EVs hold promise to improve the therapeutic efficacy of EV-mediated treatment in a wide range of diseases and disorders. Moreover, SILY-EVs possess the potential to functionalize collagen-based biomaterials and deliver therapeutic agents for regenerative medicine applications.

One-Year Follow-Up of COVID-19 Impact on Surgical Education: Clinical Training Restored but Surgical Trainee Emotional Well-Being Still at Risk.

BACKGROUND: A previous survey documented the severe disruption of the coronavirus disease 2019 pandemic on surgical education and trainee well-being during the initial surge and systemic lockdowns. Herein, we report the results of a follow-up survey inclusive of the 2020 to 2021 academic year. STUDY DESIGN: A survey was distributed to education leaders across all surgical specialties in summer 2021. We compared the proportion of participants reporting severe disruption in key areas with those of the spring 2020 survey. Aggregated differences by year were assessed using chi-square analysis. RESULTS: In 2021, severe disruption of education programs was reported by 14% compared with 32% in 2020 (p < 0.0001). Severe reductions in nonemergency surgery were reported by 38% compared with 87% of respondents in 2020. Severe disruption of expected progression of surgical trainee autonomy by rank also significantly decreased to 5% to 8% in 2021 from 15% to 23% in 2020 among respondent programs (p < 0.001). In 2021 clinical remediation was reported for postgraduate year 1 to 2 and postgraduate year 3 to 4, typically through revised rotations (19% and 26%) and additional use of simulation (20% and 19%) maintaining trainee promotion and job placement. In 2021, surgical trainees' physical safety and health were reported as less severely impacted compared with 2020; however, negative effects of isolation (77%), burnout (75%), and the severe impact on emotional well-being (17%) were prevalent. CONCLUSIONS: One year after the initial coronavirus disease 2019 outbreak, clinical training and surgical trainee health were less negatively impacted. Disruption of emotional well-being remained high. Future needs include better objective measures of clinical competence beyond case numbers and the implementation of novel programs to promote surgical trainee health and well-being.

The hidden mortality of pediatric firearm violence.

INTRODUCTION: Firearms and motor vehicle collisions (MVC) are leading causes of mortality in children. We hypothesized that firearm injuries would have a higher mortality than MVCs in children and a higher level of resource utilization METHODS: Trauma patients <18 years old at a Level 1 pediatric trauma center sustaining gunshot wounds (GSW) or MVCs 2009-2019 were included. The primary outcome was mortality. The secondary outcome was immediate surgery. The California Department of Public Health's Overall Injury Surveillance tool was queried for patients <18 with GSW or MVC 2006-2015 to compare statewide case fatality rates (CFRs), and analyze proportions of GSWs by intent: assault, self-inflicted, and unintentional. RESULTS: Of 13,840 pediatric trauma patients at our institution, 295 GSWs (2.1%) and 4467 MVCs (32.3%) were included. Mortality was higher for GSWs (7.5% vs. 0.8%, p<0.0001). GSW patients were more likely to require immediate surgery (34.4% vs. 11.2%, p<0.0001). On multivariable analysis, GSW patients were 7.8-times more likely to die than MVC patients (OR 7.83, 95% CI 3.68-16.66, p<0.0001), adjusted for age, sex, and injury severity. Statewide, there were 10,790 pediatric GSWs with 1586 deaths (CFR 14.7%) vs. 710 deaths in 261,363 children in MVCs (CFR 0.3%, p<0.0001). The GSW CFR rose (13.4% to 16.5%, p = 0.05) while the MVC CFR decreased (0.5% to 0.2%, p<0.0001) in 2015 vs. 2006. CONCLUSION: Firearm violence in pediatric patients is significantly more lethal than MVCs and is resource intensive. The case fatality rate for pediatric firearm violence is rising. Resources must be directed at preventing pediatric firearm injuries. LEVEL OF EVIDENCE: Prognosis study, Level II.

Early investigations into improving bowel and bladder function in fetal ovine myelomeningocele repair.

INTRODUCTION: Fetal myelomeningocele (MMC) repair improves lower extremity motor function. We have previously demonstrated that augmentation of fetal MMC repair with placental mesenchymal stromal cells (PMSCs) seeded on extracellular matrix (PMSC-ECM) further improves motor function in the ovine model. However, little progress has been made in improving bowel and bladder function, with many patients suffering from neurogenic bowel and bladder. We hypothesized that fetal MMC repair with PMSC-ECM would also improve bowel and bladder function. METHODS: MMC defects were surgically created in twelve ovine fetuses at median gestational age (GA) 73 days, followed by defect repair at GA101 with PMSC-ECM. Fetuses were delivered at GA141. Primary bladder function outcomes were voiding posture and void volumes. Primary bowel function outcome was anorectal manometry findings including resting anal pressure and presence of rectoanal inhibitory reflex (RAIR). Secondary outcomes were anorectal and bladder detrusor muscle thickness. PMSC-ECM lambs were compared to normal lambs (n = 3). RESULTS: Eighty percent of PMSC-ECM lambs displayed normal voiding posture compared to 100% of normal lambs (p = 1). Void volumes were similar (PMSC-ECM 6.1 ml/kg vs. normal 8.8 ml/kg, p = 0.4). Resting mean anal pressures were similar between cohorts (27.0 mmHg PMSC-ECM vs. normal 23.5 mmHg, p = 0.57). RAIR was present in 3/5 PMSC-ECM lambs that underwent anorectal manometry and all normal lambs (p = 0.46). Thicknesses of anal sphincter complex, rectal wall muscles, and bladder detrusor muscles were similar between cohorts. CONCLUSION: Ovine fetal MMC repair augmented with PMSC-ECM results in near-normal bowel and bladder function. Further work is needed to evaluate these outcomes in human patients.

Impact of Gestational Age on Neuroprotective Function of Placenta-Derived Mesenchymal Stromal Cells.

INTRODUCTION: The Management of Myelomeningocele Study demonstrated that in utero repair of myelomeningocele improved motor outcomes compared with postnatal repair. However, even after in utero repair, many children were still unable to walk. We have previously demonstrated that augmentation of in utero repair with early-gestation placental mesenchymal stromal cells (PMSCs) improves motor outcomes in lambs compared with standard in utero repair. The neuroprotective potential of PMSCs of all gestational ages has not been evaluated previously. METHODS: PMSCs were isolated from discarded first trimester (n = 3), second trimester (n = 3), and term (n = 3) placentas by explant culture. Cytokine array analysis was performed. Secretion of two neurotrophic factors, brain-derived neurotrophic factor and hepatocyte growth factor, was evaluated by enzyme-linked immunosorbent assay. An in vitro neuroprotective assay demonstrated to be associated with in vivo function was performed. RESULTS: All cell lines secreted immunomodulatory and neuroprotective cytokines and secreted the neurotrophic factors evaluated. Increased neuroprotective capabilities relative to no PMSCs were demonstrated in two of the three first trimester cell lines (5.61, 4.96-6.85, P < 0.0001 and 2.67, 1.67-4.12, P = 0.0046), two of the three second trimester cell lines (2.82, 2.45-3.43, P = 0.0004 and 3.25, 2.62-3.93, P < 0.0001), and two of the three term cell lines (2.72, 2.32-2.92, P = 0.0033 and 2.57, 1.41-4.42, P = 0.0055). CONCLUSIONS: We demonstrated variation in neuroprotective function between cell lines and found that some cell lines from each trimester had neuroprotective properties. This potentially expands the donor pool of PMSCs for clinical use. Further in-depth studies are needed to understand potential subtle differences in cell function at different gestational ages.

Impact of the COVID-19 pandemic on surgical trainee education and well-being spring 2020-winter 2020: A path forward.

BACKGROUND: The time course and longitudinal impact of the COVID -19 pandemic on surgical education(SE) and learner well-being (LWB)is unknown. MATERIAL AND METHODS: Check-in surveys were distributed to Surgery Program Directors and Department Chairs, including general surgery and surgical specialties, in the summer and winter of 2020 and compared to a survey from spring 2020. Statistical associations for items with self-reported ACGME Stage and the survey period were assessed using categorical analysis. RESULTS: Stage 3 institutions were reported in spring (30%), summer (4%) [p < 0.0001] and increased in the winter (18%). Severe disruption (SD) was stage dependent (Stage 3; 45% (83/184) vs. Stages 1 and 2; 26% (206/801)[p < 0.0001]). This lessened in the winter (23%) vs. spring (32%) p = 0.02. LWB severe disruption was similar in spring 27%, summer 22%, winter 25% and was associated with Stage 3. CONCLUSIONS: Steps taken during the pandemic reduced SD but did not improve LWB. Systemic efforts are needed to protect learners and combat isolation pervasive in a pandemic.

Long-term safety evaluation of placental mesenchymal stromal cells for in utero repair of myelomeningocele in a novel ovine model.

PURPOSE: Augmentation of in utero myelomeningocele repair with human placental mesenchymal stromal cells seeded onto extracellular matrix (PMSC-ECM) improves motor outcomes in an ovine myelomeningocele model. This study evaluated the safety of PMSC-ECM application directly onto the fetal spinal cord in preparation for a clinical trial. METHODS: Laminectomy of L5-L6 with PMSC-ECM placement directly onto the spinal cord was performed in five fetal lambs at gestational age (GA) 100-106 days. Lambs and ewes were monitored for three months following delivery. Lambs underwent magnetic resonance imaging (MRI) of the brain and spine at birth and at three months. All organs from lambs and uteri from ewes underwent histologic evaluation. Lamb spinal cords and brains and ewe placentas were evaluated for persistence of PMSCs by polymerase chain reaction for presence of human DNA. RESULTS: MRIs demonstrated no evidence of abnormal tissue growth or spinal cord tethering. Histological analysis demonstrated no evidence of abnormal tissue growth or treatment related adverse effects. No human DNA was identified in evaluated tissues. CONCLUSION: There was no evidence of abnormal tissue growth or PMSC persistence at three months following in utero application of PMSC-ECM to the spinal cord. This supports proceeding with clinical trials of PMSC-ECM for in utero myelomeningocele repair. LEVEL OF EVIDENCE: N/A TYPE OF STUDY: Basic science.

Efficacy of clinical-grade human placental mesenchymal stromal cells in fetal ovine myelomeningocele repair.

BACKGROUND: While fetal repair of myelomeningocele (MMC) revolutionized management, many children are still unable to walk independently. Preclinical studies demonstrated that research-grade placental mesenchymal stromal cells (PMSCs) prevent paralysis in fetal ovine MMC, however this had not been replicated with clinical-grade cells that could be used in an upcoming human clinical trial. We tested clinical-grade PMSCs seeded on an extracellular matrix (PMSC-ECM) in the gold standard fetal ovine model of MMC. METHODS: Thirty-five ovine fetuses underwent MMC defect creation at a median of 76 days gestational age, and defect repair at 101 days gestational age with application of clinical-grade PMSC-ECM (3 × 105 cells/cm2, n = 12 fetuses), research-grade PMSC-ECM (3 × 105 cells/cm2, three cell lines with n = 6 (Group 1), n = 6 (Group 2), and n = 3 (Group 3) fetuses, respectively) or ECM without PMSCs (n = 8 fetuses). Three normal lambs underwent no surgical interventions. The primary outcome was motor function measured by the Sheep Locomotor Rating scale (SLR, range 0: complete paralysis to 15: normal ambulation) at 24 h of life. Correlation of lumbar spine large neuron density with SLR was evaluated. RESULTS: Clinical-grade PMSC-ECM lambs had significantly better motor function than ECM-only lambs (SLR 14.5 vs. 6.5, p = 0.04) and were similar to normal lambs (14.5 vs. 15, p = 0.2) and research-grade PMSC-ECM lambs (Group 1: 14.5 vs. 15, p = 0.63; Group 2: 14.5 vs. 14.5, p = 0.86; Group 3: 14.5 vs. 15, p = 0.50). Lumbar spine large neuron density was strongly correlated with motor function (r = 0.753, p<0.001). CONCLUSIONS: Clinical-grade placental mesenchymal stromal cells seeded on an extracellular matrix rescued ambulation in a fetal ovine myelomeningocele model. Lumbar spine large neuron density correlated with motor function, suggesting a neuroprotective effect of the PMSC-ECM in prevention of paralysis. A first-in-human clinical trial of PMSCs in human fetal myelomeningocele repair is underway.