Sandra K. Kabagambe

Intercostal nerve cryoablation versus thoracic epidural catheters for postoperative analgesia following pectus excavatum repair: Preliminary outcomes in twenty-six cryoablation patients ☆

BACKGROUND Multimodal pain management strategies are used for analgesia following pectus excavatum repair. However, the optimal regimen has not been identified. We describe our early experience with intercostal cryoablation for pain management in children undergoing the Nuss procedure and compare early cryoablation outcomes to our prior outcomes using thoracic epidural analgesia. METHODS A multi-institutional, retrospective review of fifty-two patients undergoing Nuss bar placement with either intercostal cryoablation (n=26) or thoracic epidural analgesia (n=26) from March 2013 to January 2016 was conducted. The primary outcome was hospital length of stay. Secondary outcomes included telemetry unit monitoring time, total intravenous narcotic use, duration of intravenous narcotic use, and postoperative complications. RESULTS Patients who underwent intercostal cryoablation had a significant reduction in the mean hospital length of stay, time in a monitored telemetry bed, total use of intravenous narcotics, and the duration of intravenous narcotic administration when compared to thoracic epidural patients. Cryoablation patients had a slightly higher rate of postoperative complications. CONCLUSION Intercostal cryoablation is a promising technique for postoperative pain management in children undergoing repair of pectus excavatum. This therapy results in reduced time to hospital discharge, decreased intravenous narcotic utilization, and has eliminated epidurals from our practice. LEVEL OF EVIDENCE Retrospective study - level III.

Fetal Surgery for Myelomeningocele: A Systematic Review and Meta-Analysis of Outcomes in Fetoscopic versus Open Repair

Background/Objectives: The Management of Myelomeningocele (MMC) Study (MOMS) showed that prenatal repair of MMC resulted in improved neurological outcomes but was associated with high rates of obstetrical complications. This study compares outcomes of open and fetoscopic MMC repair. Data Sources: PubMed and Embase studies reporting outcomes of fetal MMC repair published since the completion of the MOMS. Results: We analyzed 11 studies and found no difference in mortality or the rate of shunt placement for hydrocephalus. Percutaneous fetoscopic repair was associated with higher rates of premature rupture of membranes (91 vs. 36%, p < 0.01) and preterm birth (96 vs. 81%, p = 0.04) compared to open repair, whereas fetoscopic repair via maternal laparotomy reduced preterm birth. The rate of dehiscence and leakage from the MMC repair site was higher after both types of fetoscopic surgery (30 vs. 7%, p < 0.01), while the rate of uterine dehiscence was higher after open repair (11 vs. 0%, p < 0.01). Discussion: Fetoscopic repair is a promising alternative to open fetal MMC repair with a lower risk of uterine dehiscence; however, fetoscopic techniques should be optimized to overcome the high rate of dehiscence and leakage at the MMC repair site. A fetoscopic approach via maternal laparotomy reduces the risk of preterm birth.

Fetal surgical repair with placenta-derived mesenchymal stromal cell engineered patch in a rodent model of myelomeningocele

PURPOSE The purpose of this study is to determine the feasibility of fetal surgical repair of myelomeningocele (MMC) in a rodent model using human placental mesenchymal stromal cells (PMSCs) seeded onto extracellular matrix (ECM) and to characterize the resulting changes in spinal cord tissue. METHODS Fetal rodents with retinoic acid (RA) induced MMC underwent surgical repair of the MMC defect using an ECM patch on embryonic age (EA) 19 and were collected via caesarean section on EA 21. Various seeding densities of PMSC-ECM and ECM only controls were evaluated. Cross-sectional compression (width/height) and apoptotic cell density of the lumbosacral spinal cord were analyzed. RESULTS 67 dams treated with 40mg/kg of RA resulted in 352 pups with MMC defects. 121 pups underwent MMC repair, and 105 (86.8%) survived to term. Unrepaired MMC pups had significantly greater cord compression and apoptotic cell density compared to normal non-MMC pups. Pups treated with PMSC-ECM had significantly less cord compression and demonstrated a trend towards decreased apoptotic cell density compared to pups treated with ECM only. CONCLUSION Surgical repair of MMC with a PMSC-seeded ECM disc is feasible with a postoperative survival rate of 86.8%. Fetal rodents repaired with PMSC-ECM have significantly less cord deformity and decreased histological evidence of apoptosis compared to ECM only controls.

High density placental mesenchymal stromal cells provide neuronal preservation and improve motor function following in utero treatment of ovine myelomeningocele

PURPOSE The purpose of this study was to determine whether seeding density of placental mesenchymal stromal cells (PMSCs) on extracellular matrix (ECM) during in utero repair of myelomeningocele (MMC) affects motor function and neuronal preservation in the ovine model. METHODS MMC defects were surgically created in 33 fetuses and repaired following randomization into four treatment groups: ECM only (n = 10), PMSC-ECM (42 K cells/cm2) (n = 8), PMSC-ECM (167 K cells/cm2) (n = 7), or PMSC-ECM (250-300 K cells/cm2) (n = 8). Motor function was evaluated using the Sheep Locomotor Rating Scale (SLR). Serial sections of the lumbar spinal cord were analyzed by measuring their cross-sectional areas which were then normalized to normal lambs. Large neurons (LN, diameter 30-70 μm) were counted manually and density calculated per mm2 gray matter. RESULTS Lambs treated with PMSCs at any density had a higher median SLR score (15 [IQR 13.5-15]) than ECM alone (6.5 [IQR 4-12.75], p = 0.036). Cross-sectional areas of spinal cord and gray matter were highest in the PMSC-ECM (167 K/cm2) group (p = 0.002 and 0.006, respectively). LN density was highest in the greatest density PMSC-ECM (250-300 K/cm2) group (p = 0.045) which positively correlated with SLR score (r = 0.807, p < 0.0001). CONCLUSIONS Fetal repair of myelomeningocele with high density PMSC-ECM resulted in increased large neuron density, which strongly correlated with improved motor function. TYPE OF STUDY Basic science. LEVEL OF EVIDENCE N/A.

Lessons from the Barn to the Operating Suite: A Comprehensive Review of Animal Models for Fetal Surgery

The International Fetal Medicine and Surgery Society was created in 1982 and proposed guidelines for fetal interventions that required demonstrations of the safety and feasibility of intended interventions in animal models prior to application in humans. Because of their short gestation and low cost, small animal models are useful in early investigation of fetal strategies. However, owing to the anatomic and physiologic differences between small animals and humans, repeated studies in large animal models are usually needed to facilitate translation to humans. Ovine (sheep) models have been used the most extensively to study the pathophysiology of congenital abnormalities and to develop techniques for fetal interventions. However, nonhuman primates have uterine and placental structures that most closely resemble those of humans. Thus, the nonhuman primate is the ideal model to develop surgical and anesthetic techniques that minimize obstetrical complications.

Placental mesenchymal stromal cells seeded on clinical grade extracellular matrix improve ambulation in ovine myelomeningocele

PURPOSE The purpose of this study was to investigate the effects of placental mesenchymal stromal cells (PMSCs) seeded on a clinical grade porcine small intestinal submucosa (SIS)-derived extracellular matrix (ECM) on hindlimb motor function in an ovine fetal repair model of myelomeningocele (MMC). METHODS MMC defects were surgically created in 21 fetuses at median gestational age 78 (range 76-83) days. Fetuses were randomly assigned to repair 25days later with ECM only or PMSC-ECM. Surviving fetuses were delivered at term. Motor function was evaluated using the Sheep Locomotor Rating (SLR) scale (0-15). Histologic analysis of the spinal cord (SC) was completed. RESULTS Fetal viability was 71%. 5 of 8 (63%) lambs repaired with PMSC-ECM ambulated independently versus only 1 of 6 (17%) repaired with ECM only (p=0.04, χ2 test). SLR scores and large neuron densities were higher in the PMSC-ECM group. The cross-sectional areas of the SC and the gray matter were equally preserved. CONCLUSIONS Fetal repair of MMC with PMSCs seeded on SIS-ECM improves hindlimb motor function in lambs. Using ECM helps to preserve the architecture of the SC, but adding PMSCs improves the lambs ability to walk and increases large neuron density. Clinical studies are needed to show benefits in humans. LEVELS OF EVIDENCE/TYPE OF STUDY Basic Science.

Isolation of myogenic progenitor cell population from human placenta: A pilot study

PURPOSE The purpose of this study was to demonstrate a method of isolating myogenic progenitor cells from human placenta chorionic villi and to confirm the myogenic characteristics of the isolated cells. METHODS Cells were isolated from chorionic villi of a second trimester male placenta via a combined enzymatic digestion and explant culture. A morphologically distinct subpopulation of elongated and multinucleated cells was identified. This subpopulation was manually passaged from the explant culture, expanded, and analyzed by fluorescence in situ hybridization (FISH) assay, immunocytochemistry, and flow cytometry. Myogenic characteristics including alignment and fusion were tested by growing these cells on aligned polylactic acid microfibrous scaffold in a fusion media composed of 2% horse serum in Dulbeccos modified Eagle medium/high glucose. RESULTS The expanded subpopulation was uniformly positive for integrin α-7. Presence of Y-chromosome by FISH analysis confirmed chorionic villus origin rather than maternal cell contamination. Isolated cells grew, aligned, and fused on the microfibrous scaffold, and they expressed myogenin, desmin, and MHC confirming their myogenic identity. CONCLUSION Myogenic progenitor cells can be isolated from human chorionic villi. This opens the possibility for translational and clinical applications using autologous myogenic cells for possible engraftment in treatment of chest and abdominal wall defects.

New directions in fetal surgery for myelomeningocele

The treatment of children with myelomeningocele (MMC) has improved over time, from supportive management to early postnatal closure to prenatal repair of the defect. The Management of Myelomeningocele Study (MOMS) showed that prenatal repair of MMC resulted in improved neurological outcomes compared to postnatal closure. Follow-up studies showed that prenatal repair was, as with any other fetal intervention, associated with higher rates of obstetrical complications. There was no significant difference in urological outcomes. Long-term follow-up of ambulatory status, executive functioning, and urological outcomes is needed to determine the durable effects of fetal MMC repair on mobility, functional independence, and the prevalence of renal insufficiency in patients with MMC who survive to adulthood. The future of fetal MMC repair consists of developing strategies to reduce maternal morbidity and improve infant outcomes. Fetoscopic MMC repair has been suggested as an alternative to open repair that may reduce obstetrical complications and the need for cesarean delivery in subsequent pregnancies. Translational research using mesenchymal stromal cells to augment fetal repair of ovine MMC has shown improvement in motor function.