Stem cell activation during distraction enterogenesis in the murine colon.

PURPOSE: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Long-term safety of intraluminal spring-mediated bowel lengthening.

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.

The effect of spring diameter on porcine ileal distraction enterogenesis.

PURPOSE: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Generation of Porcine Ileum Through Spring-Mediated Mechanical Distraction.

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 ± 66.4 g/d. Spring segments lengthened 1.5 ± 0.7 cm 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 ± 1.1 cells/mm versus 3.2 ± 1.2 cells/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.

Gastrointestinal Myoelectric Measurements via Simultaneous External and Internal Electrodes in Pigs.

INTRODUCTION: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Ten-year experience with laparoscopic pedicled omental flap for cerebral revascularization in patients with Moyamoya disease.

BACKGROUND: The omental flap has numerous extraperitoneal applications in reconstruction and revascularization given its favorable immunologic and angiogenic properties. In patients with Moyamoya disease, cerebral revascularization using a pedicled omental flap has proven to be a viable option following direct revascularization procedures. Historically, harvesting omentum involved laparotomy with the associated risk of complications; herein we describe outcomes from a 10-year experience of laparoscopic harvesting of pedicled omental flap for cerebral revascularization in Moyamoya patients. METHODS: A retrospective chart review was performed of all patients with Moyamoya disease who underwent laparoscopic omental cerebral transposition between 2011 and 2021. Intraoperative and postoperative complications, length of stay (LOS), and outcomes at follow-up were analyzed. RESULTS: Twenty-one patients underwent the procedure during the study period. Three intraoperative complications occurred (one segmental transverse colectomy for mesenteric injury, one converted to omental free flap, and one requiring micro anastomosis). Average overall LOS was 6 ± 6 days, with 3 ± 3.5 days in the ICU (mean±SD). Following discharge, complications included epigastric incisional hernia at the graft fascial exit site, recurrent neck pain at subcutaneous tunneling site, and partial scalp necrosis. One patient required subsequent direct bypass seven months after the initial procedure owing to the progression of the disease. All other patients had partial or complete resolution of symptoms. CONCLUSION: Our retrospective observational study indicates that laparoscopic pedicled omental flap mobilization and transposition is a safe and effective method of indirect cerebral revascularization in patients with Moyamoya disease. LEVEL OF EVIDENCE: N/A.

Distraction enterogenesis in the murine colon.

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.

Sutureless closure for the management of gastroschisis.

Gastroschisis is a common congenital anomaly in which the midgut fails to return to the abdominal cavity resulting in exposed intestines, which are not covered by a membrane in a neonate. The incidence of gastroschisis has been increasing worldwide resulting in an evolving medical and surgical management. Gastroschisis can be either simple or complicated. Complicated gastroschisis occurs when gastroschisis is associated with gastrointestinal conditions such as intestinal atresia, volvulus, stenosis or perforation. In this instance, the mortality and morbidity of patients significantly increases. Initial management of gastroschisis requires a multi-modal, interdisciplinary approach in order to successfully care for a neonate. Patients should be managed in a neonatal intensive care unit under the care of intensivists, respiratory therapists and pediatric surgeons. Temperature regulation, hydration and protection of the bowel are of the utmost priorities. Surgical management of gastroschisis focuses on reduction of the bowel and closure of the abdominal wall defect. Initially, the defect was closed primarily with suture, however, more recently, a sutureless closure has become prevalent. This, in conjunction with use of a silo, has led to a shift from the operating room and general anesthesia to the bedside. This article aims to discuss the presentation, diagnosis and management of gastroschisis.

Novel Neonatal Umbilical Catheter Protection and Stabilization Device in In vitro Model of Catheterized Human Umbilical Cords: Effect of Material and Venting on Bacterial Colonization.

OBJECTIVE: Umbilical central lines deliver life-saving medications and nutrition for neonates; however, complications associated with umbilical catheters (UCs) occur more frequently than in adults with central lines (i.e., line migration, systemic infection). We have developed a device for neonatal UC protection and stabilization to reduce catheter exposure to bacteria compared with the standard of care: "goal post" tape configuration. This study analyzes the effect of device venting and material on bacterial load of human umbilical cords in vitro. STUDY DESIGN: Catheters were inserted into human umbilical cord segments in vitro, secured with plastic or silicone vented prototype versus tape, and levels of bacterial colonization were compared between groups after 7 days of incubation. RESULTS: Nonvented plastic prototype showed increased bacterial load compared with goal post (p = 0.04). Colonization was comparable between the goal post and all vented plastic prototypes (p ≥ 0.30) and when compared with the vented silicone device (p = 1). CONCLUSION: A novel silicone device does not increase external bacterial colonization compared with the current standard of care for line securement, and may provide a safe, convenient alternative to standard adhesive tape for UC stabilization. Future studies are anticipated to establish safety in vivo, alongside benefits such as migration and infection reduction.

Irreversible Electroporation for De-epithelialization of Murine Small Intestine.

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 1.5 cm 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 3 d 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.

Biomechanics of small intestine during distraction enterogenesis with an intraluminal spring.

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.

Biomechanical signaling and collagen fiber reorientation during distraction enterogenesis.

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.

Methotrexate Chemotherapy Induces Persistent Tri-glial Dysregulation that Underlies Chemotherapy-Related Cognitive Impairment.

Chemotherapy results in a frequent yet poorly understood syndrome of long-term neurological deficits. Neural precursor cell dysfunction and white matter dysfunction are thought to contribute to this debilitating syndrome. Here, we demonstrate persistent depletion of oligodendrocyte lineage cells in humans who received chemotherapy. Developing a mouse model of methotrexate chemotherapy-induced neurological dysfunction, we find a similar depletion of white matter OPCs, increased but incomplete OPC differentiation, and a persistent deficit in myelination. OPCs from chemotherapy-naive mice similarly exhibit increased differentiation when transplanted into the microenvironment of previously methotrexate-exposed brains, indicating an underlying microenvironmental perturbation. Methotrexate results in persistent activation of microglia and subsequent astrocyte activation that is dependent on inflammatory microglia. Microglial depletion normalizes oligodendroglial lineage dynamics, myelin microstructure, and cognitive behavior after methotrexate chemotherapy. These findings indicate that methotrexate chemotherapy exposure is associated with persistent tri-glial dysregulation and identify inflammatory microglia as a therapeutic target to abrogate chemotherapy-related cognitive impairment. VIDEO ABSTRACT.

Endoscopic Division of Duodenal Web Causing Near Obstruction in 2-Year-Old with Trisomy 21.

INTRODUCTION: Surgical intervention for duodenal atresia most commonly entails duodenoduodenostomy in the neonatal period. Occasionally, type I duodenal atresia with incomplete obstruction may go undiagnosed until later in life. Endoscopic approach to dividing intestinal webs has been reported as successful in patients as young as 7 days of age, and can be a useful modality particularly in patients with comorbidities who may not tolerate open or laparoscopic surgery. METHODS: A 2-year-old female with a history of trisomy 21 and tetralogy of Fallot underwent laparoscopic and endoscopic exploration of intestinal obstruction as seen on upper gastrointestinal series for symptoms of recurrent emesis and weight loss. After laparoscopy confirmed a duodenal web as the cause of intestinal obstruction, endoscopic division of the membrane was carried out with a triangle tip electrocautery knife and 15 mm radially dilating balloon. RESULTS: The patient tolerated the procedure well, and also tolerated full age-appropriate diet by time of discharge on postoperative day 2. She remains asymptomatic as of 6 months postoperatively. CONCLUSIONS: This report describes a successful endoscopic approach for definitive treatment of a duodenal web in a 2-year-old girl with trisomy 21, and laparoscopy confirmed no intraabdominal obstructive process or complication from endoscopy. Endoscopy enables minimal recovery time and suggests an improved method of duodenal web division over pure surgical intervention.

Neuronal activity promotes oligodendrogenesis and adaptive myelination in the mammalian brain.

Myelination of the central nervous system requires the generation of functionally mature oligodendrocytes from oligodendrocyte precursor cells (OPCs). Electrically active neurons may influence OPC function and selectively instruct myelination of an active neural circuit. In this work, we use optogenetic stimulation of the premotor cortex in awake, behaving mice to demonstrate that neuronal activity elicits a mitogenic response of neural progenitor cells and OPCs, promotes oligodendrogenesis, and increases myelination within the deep layers of the premotor cortex and subcortical white matter. We further show that this neuronal activity-regulated oligodendrogenesis and myelination is associated with improved motor function of the corresponding limb. Oligodendrogenesis and myelination appear necessary for the observed functional improvement, as epigenetic blockade of oligodendrocyte differentiation and myelin changes prevents the activity-regulated behavioral improvement.

Effects of stress and motivation on performing a spatial task.

Learning is ubiquitous in the animal kingdom but has been studied extensively in only a handful of species. Moreover, learning studied under laboratory conditions is typically unrelated to the animal's natural environment or life history. Here, we designed a task relevant to the natural behavior of male African cichlid fish (Astatotilapia burtoni), to determine if they could be trained on a spatial task to gain access to females and shelter. We measured both how successfully animals completed this task over time and whether and how immediate early gene and hormone expression profiles were related to success. While training fish in a maze, we measured time to task completion, circulating levels of three key hormones (cortisol, 11-ketotestosterone, and testosterone) and mRNA abundance of seven target genes including three immediate early genes (that served proxies for brain activity) in nine brain regions. Data from our subjects fell naturally into three phenotypes: fish that could be trained (learners), fish that could not be trained (non-learners) and fish that never attempted the task (non-attempters). Learners and non-learners had lower levels of circulating cortisol compared to fish that never attempted the task. Learners had the highest immediate early gene mRNA levels in the homologue of the hippocampus (dorsolateral telencephalon; Dl), lower cortisol (stress) levels and were more motivated to accomplish the task as measured by behavioral observations. Fish that never attempted the task showed the lowest activity within the Dl, high stress levels and little to no apparent motivation. Data from non-learners fell between these two extremes in behavior, stress, and motivation.