Injectable small intestinal submucosa: Preliminary evaluation for use in endoscopic urological surgery

Purpose: We evaluated the possible use of small intestinal submucosa in endoscopic urological surgery by assessing the smooth muscle regenerative capabilities and physical response of various forms of injectable small intestinal submucosa in the canine model. Materials and Methods: In blinded fashion we injected small intestinal submucosa in 12 dogs submucosally under direct vision using a 20 gauge endoscopic needle. The 4 small intestinal submucosa formulations varied in harvesting method and sterilization technique. Animals were divided into groups of 3 and sacrificed 2 weeks, 6 weeks, 3 months and 6 months after surgery. Each injection site was analyzed grossly and histologically. Smooth muscle regeneration was identified by α-smooth muscle actin immunohistochemical staining. Results: We identified 2 injectable small intestinal submucosa formulations that induced progressive smooth muscle regeneration at the site of submucosal injection compared with controls. De novo smooth muscle cells appeared in single cell aggregates as early as 6 weeks and in globular aggregates at 3 months. By 6 months early muscle bundle formation was noted. These 2 injectable small intestinal submucosa formulations also had the best submucosal volume preservation of about 25% of injected material during the study period. Conclusions: Injectable small intestinal submucosa promotes progressive submucosal smooth muscle regeneration in the canine bladder. The combined regenerative and bulking abilities of injectable small intestinal submucosa make this compound unique and novel. The clinical usefulness of injectable small intestinal submucosa for endoscopic correction of reflux and incontinence deserves further investigation.