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.

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.

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.

An in vitro bacterial surface migration assay underneath sterile barrier material commonly found in a hospital setting

OBJECTIVE

To determine what barrier material used in hospital neonatal intensive care units most effectively blocks bacterial migration.

STUDY DESIGN

Bacterial migration distance was compared across simple and complex solid media using Escherichia coli, an early and common neonatal gut colonizer, and Staphylococcus aureus, a common skin bacterium, across polystyrene, medical-grade silicone, hydrocolloid dressing and transparent film dressing as barrier materials on complex solid media.

RESULTS

Bacterial migration was significantly greater on complex versus simple solid media. Bacteria migrated farthest beneath hydrocolloid dressing and transparent film dressing, while migration underneath polystyrene and medical-grade silicone was generally comparable to no barrier.

CONCLUSIONS

Commonly used hydrocolloid dressing and transparent film dressing surprisingly increases bacterial migration, possibly by providing a wet capillary surface for bacteria to attach to or inducing biofilm formation. Using polystyrene or silicone to interface with the site of catheter insertion may best avoid a bacterial wicking phenomenon.

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.