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

Purpose: We evaluated the possible use of small intestinal submucosa in end oscopic urological surgery by assessing the smooth muscle regenerative capa bilities and physical response of various forms of injectable small intesti nal submucosa in the canine model. Materials and Methods: In blinded fashion we injected small intestinal subm ucosa in 12 dogs submucosally under direct vision using a 20 gauge endoscop ic needle. The 4 small intestinal submucosa formulations varied in harvesti ng method and sterilization technique. Animals were divided into groups of 3 and sacrificed 2 weeks, 6 weeks, 3 months and 6 months after surgery. Eac h injection site was analyzed grossly and histologically. Smooth muscle reg eneration was identified by alpha-smooth muscle actin immunohistochemical s taining. Results: We identified 2 injectable small intestinal submucosa formulations that induced progressive smooth muscle regeneration at the site of submuco sal 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 inj ectable small intestinal submucosa formulations also had the best submucosa l volume preservation of about 25% of injected material during the study pe riod. Conclusions: Injectable small intestinal submucosa promotes progressive sub mucosal smooth muscle regeneration in the canine bladder. The combined rege nerative and bulking abilities of injectable small intestinal submucosa mak e this compound unique and novel. The clinical usefulness of injectable sma ll intestinal submucosa for endoscopic correction of reflux and incontinenc e deserves further investigation.