Functional evaluation of the grafted wall with porcine-derived small intestinal submucosa (SIS) to a stomach defect in rats

Background Small intestinal submucosa (SIS) represents a novel bio-scaffolding material that may be used to repair hollow-organ defects. However, it is unclear whether neurophysiologic responses return to SIS-grafted areas in the gut. We evaluated the functional recovery of a stomach defect grafted with the porcine-derived SIS. Methods Twelve rats had a full-thickness defect created in the stomach. SIS was secured to the gastric wall. After 6 months, muscle strips were harvested from within the grafted area to perform both a histologic and a functional study. Additional full-thickness muscle strips were harvested from the posterior in the same stomach as controls. A dose response curve was obtained with carbachol (CCH) or sodium nitroprusside (SNP). Activation of intrinsic nerves was achieved by electrical field stimulation (EFS). Results The response to CCH and amplitude in EFS showed tonic contraction in both controls and SIS strips in a concentration-dependent and frequency-dependent manner. The magnitude after each stimulation was significantly lower in SIS strips compared with controls ( P < .01). However, the contraction ratio of EFS to ED50 of CCH was not significantly different between the groups. Additionally, SNP produced relaxation in both strips in a concentration-dependent manner. Histologic findings revealed that an insufficient amount of smooth-muscle cells existed in the muscularis propria, whereas compensated growth was observed in the submucosa with nerve regeneration. Conclusions This study demonstrates that SIS provides a template for nerve migration to the graft in the rodent stomach. Innervations showed a similar distribution to that observed in the controls. The clinical implications of such findings warrant additional investigation.