N. Huynh1, J. D. Rouch1, G. Dubrovsky1, A. Scott1, M. Stelzner2, S. Shekherdimian1, J. Dunn1 1University Of California – Los Angeles,Division Of Pediatric Surgery, Department Of Surgery, David Geffen School Of Medicine,Los Angeles, CA, USA 2University Of California – Los Angeles,Division Of General Surgery, Department Of Surgery,Los Angeles, CA, USA
Introduction:
Distraction enterogenesis has been investigated as a novel treatment for patients with short bowel syndrome (SBS). Given the variability of intestinal sizes, it is critical to determine safe, translatable spring characteristics in different sized animal models prior to clinical use. Self-expanding nitinol springs have been shown to lengthen intestines in rats and pigs. Here we show spring-mediated intestinal lengthening is scalable and feasible in a murine model.
Methods:
A 10 mm nitinol spring was compressed to 3 mm and placed in a 5 mm intestinal segment isolated from continuity in mice. A non-compressed nitinol spring placed in a 5 mm isolated intestinal segment served as a control. Spring parameters were proportionally extrapolated from previous rodent and porcine spring parameters to accommodate the smaller size of murine intestines. After 1 to 2 weeks, the intestinal segments were examined for size and retrieved for histological analysis.
Results:
Intestinal segments with compressed spring constants between 0.2 to 1.4 N/m lengthened from 5 to 9.3 ± 1.0 mm (Figure), whereas control segments lengthened from 5 to 6.0 ± 0.5 mm (p<0.01). Diameter of both groups increased similarly, 1.5 to 3.1 ± 0.1 mm and 1.5 to 3.1 ± 0.8 mm. Perforation of the isolated intestinal segment was noted in two animals when the spring constant was greater than 2 N/m. Histologically, lengthened segments had increased smooth muscle thickness and crypt depth in comparison to normal small intestine.
Conclusion:
Self-expanding nitinol springs, which exert up to 1.4 N/m, can safely yield 2-fold distraction enterogenesis in length and diameter in a scalable mouse model. Not only does this study derive the safe ranges and translatable spring characteristics in a scalable murine model for patients with SBS, it also demonstrates the feasibility of spring-mediated intestinal lengthening in a mouse, which can be used to study this technique in transgenic mice in the future.
