Ileal lengthening through internal distraction: A novel procedure for ultrashort bowel syndrome.

Purpose: Ultrashort bowel syndrome is a rare, but morbid surgical problem without effective treatment. Recent clinical analysis has demonstrated the critical influence of ileal length on ultimate enteral autonomy. Surgical techniques to increase ileal length in nondilated bowel do not exist. We describe a novel technique to lengthen ileum in children with ultrashort bowel syndrome. Methods: Beginning in May 2021 prospective candidate children were identified. Candidacy for ileal tube lengthening included diagnosis of ultrashort bowel syndrome, intact ileocecal valve with remnant ileum, and proximal intestinal stoma or draining gastrostomy. Informed consent was obtained. Following laparoscopic lysis of adhesions, a balloon catheter was inserted through a left flank stab incision and into the lumen of the remnant ileum around a purse string suture. Cecopexy was performed in the right-lower quadrant. Clips were used to mark the cecum and the proximal extent of ileum. The catheter length was fixed externally at the completion of the procedure. Serial x-rays were used to measure distraction effect while increasing tension was applied to the catheter over the subsequent weeks. Ileal tube lengthening was performed until the end of the catheter was reached or the tube was dislodged. A contrast study was performed at the completion of lengthening. Intestinal length at time of restoration of continuity and clinical outcomes were recorded. Results: Four infants were enrolled from May 2021-July 2023. Diagnoses leading to ultrashort bowel syndrome were mesenteric teratoma, necrotizing enterocolitis, and multiple intestinal atresia. At the time of restoration of intestinal continuity, a median of 1.75 cm (45 %) additional ileal length was achieved at a median of 25.5 days. There were no serious complications following ileal tube lengthening and no additional operative interventions were required. Conclusions: Ileal lengthening through internal distraction is a feasible surgical intervention to salvage ileum for infants with ultrashort bowel syndrome. Ileal tube lengthening may result in distraction enterogenesis, providing a novel intervention to increase intestinal length. Level of evidence: IV (Case series without comparison group).

Mesenteric neovascularization during spring-mediated intestinal lengthening.

BACKGROUND: Short gut syndrome, a condition characterized by inadequate absorption of nutrients owing to decreased bowel length, has minimal avenues for treatment. We have proposed spring-mediated distraction enterogenesis to lengthen bowel in porcine jejunum as a treatment for short gut. We aim to evaluate the extent of mesenteric neovascularization in segments of lengthened bowel via spring-mediated enterogenesis. METHODS: Female juvenile Yucatan pigs underwent laparotomy and insertion of gelatin-encapsulated compressed nitinol springs, held in place with plication sutures, into the jejunum. At surgery and sacrifice, macroscopic mesenteric blood vessels were counted between the plication sites. Histologic samples of the mesentery were obtained to evaluate microscopic vasculature. RESULTS: A statistically significant increase in macroscopic mesenteric blood vessels was seen after intestinal lengthening (before: 1.9 ±â€¯0.7 vessels, after: 4.7 ±â€¯1.2 vessels, p = 0.001). A statistical significance is also seen in the density of arterioles (control: 3.0 ±â€¯3.0 vessels/mm, spring: 7.0 ±â€¯9.0 vessels/mm, p = 0.01) and venules (control: 4.0 ±â€¯3.0 vessels/mm, spring: 8.0 ±â€¯8.0 vessels/mm, p = 0.003). CONCLUSION: Intestinal segments lengthened by intraluminal springs demonstrated total greater number of macroscopic vessels and microscopic blood vessels per length of mesentery as compared to control. This suggests local changes within the mesentery to recruit blood supply to growing intestine. LEVEL OF EVIDENCE: N/A TYPE OF STUDY: Treatment study.

Mechanical lengthening of porcine small intestine with decreased forces.

INTRODUCTION: short bowel syndrome is marked by inadequate intestinal surface area to absorb nutrients. Current treatments are focused on medical management and surgical reconfiguration of the dilated intestine. We propose the use of spring-mediated distraction enterogenesis as a novel intervention to increase intestinal length. Given our previous success lengthening intestinal segments using springs with spring constant ~7 N/m that exerts 0.46 N or higher, we sought to determine the minimal force needed to lengthen porcine small intestinal segments, and to explore effects on intestine over time. METHODS: Juvenile Yucatan pigs underwent laparotomy with enterotomy to introduce nitinol springs intraluminally (n = 21 springs). Bowel segments (control, spring-distracted) were retrieved on post-operative day (POD) 7 and 14, and lengths measured. Thickness of cross-sectional intestinal layers were measured using H&E, and submucosal collagen fiber orientation measured using trichrome stained sections. RESULTS: all pigs survived to POD7 and 14. Spring constants of at least 2 N/m exerting a minimum force of 0.10 N significantly lengthened intestinal segments (p <0.0001). The stronger the spring force, the greater the induced thickness of various intestinal layers at POD7 and 14. Collagen fiber orientation was also more disordered because of stronger springs. CONCLUSION: a spring constant of approximately 2 N/m exerting 0.10 N and greater significantly lengthens intestinal segments and stimulates intestinal structural changes at POD7 and 14. This suggests a decreased force is capable of inducing spring-mediated distraction enterogenesis.

Intestinal lengthening via multiple in-continuity springs.

BACKGROUND: Short bowel syndrome is a debilitating condition with few effective treatments. Spring-mediated distraction enterogenesis can be used to lengthen intestine. The purpose of this study is to determine whether multiple springs in series can safely increase the total amount of lengthening. METHODS: Juvenile mini-Yucatan pigs each received three nitinol springs placed within their jejunum. Plication was used to narrow the intestine around each spring to secure them. Compressed springs were used in the experimental group, while uncompressed springs were used in the control group. The intestine was examined 3 weeks later for lengthening and histologic changes. RESULTS: All pigs tolerated diets postoperatively with continued weight gain, and no dilation or obstruction of the intestine was observed. Segments of intestine that contained compressed springs had a significant increase in length from 2.5 cm to 3.9 ±â€¯0.2 cm per spring, compared to segments containing control springs that showed no change (p < 0.001). CONCLUSIONS: Intestinal plication can be safely used to secure multiple springs in series to achieve intestinal lengthening without compromising intestinal function. Using several springs at once allows for a greater amount of total lengthening. This is a promising model that has potential in the treatment of short bowel syndrome.

Double plication for spring-mediated in-continuity intestinal lengthening in a porcine model.

BACKGROUND: Short bowel syndrome is a condition with substantial morbidity and mortality, yet definitive therapies are lacking. Distraction enterogenesis uses mechanical force to "grow" new intestine. In this study, we examined whether intestinal plication can be used to safely achieve spring-mediated intestinal lengthening in a functioning segment of jejunum in its native position. METHODS: A total of 12 juvenile, miniature Yucatan pigs underwent laparotomy to place either compressed springs or expanded springs within a segment of jejunum (n = 6 per group). The springs were secured within the jejunum by performing intestinal plication to narrow the intestinal lumen around the spring. After 3 weeks, the jejunum was retrieved and examined for lengthening and for histologic changes. RESULTS: There were no intraoperative or postoperative complications, and the pigs tolerated their diets and gained weight. Segments of jejunum containing expanded springs showed no significant change in length over the 3 weeks. In contrast, jejunum containing compressed springs showed nearly a 3-fold increase in length (P < .001). Histology of the retrieved jejunum showed a significant increase in thickness of the muscularis propria and in crypt depth relative to normal jejunum. CONCLUSION: Intestinal plication is effective in securing endoluminal springs to lengthen the jejunum. This approach is a clinically relevant model because it allows for normal GI function and growth of animals during intestinal lengthening, which may be useful in lengthening intestine in patients with short bowel syndrome.

Analyses of cell growth in tissue-engineering scaffolds.

Cell growth is critical to the regeneration of most tissues. Current methods for analyzing cell growth in scaffolds used for tissue engineering are reviewed in the context of their limitations. A mathematical model for analyzing cell growth in scaffolds is presented to highlight the key parameters that govern cell growth. To overcome the diffusion barrier that limits the formation of thicker tissues, strategies to promote better nutrient delivery are discussed.