Ureteral segment replacement using a circumferential small-intestinal submucosa xenogenic graft

We wished to determine whether small-intestinal submucosa (SIS) will epithe lialize when used as a ureteral replacement material. An 11-mm segment of n ative ureter was excised from eight New Zealand White rabbits and replaced with an 11-mm porcine SIS graft, which was circumferentially wrapped around a ureteral stent. The SIS ureteral grafts were harvested at 11 days or 35 days postimplantation and examined grossly and by standard light microscopy techniques. Partial epithelialization with the ingrowth of urothelium, smo oth muscle cells, and blood vessels was observed in the grafts harvested at 11 days postimplantation. The SIS ureteral grafts examined at 35 days post implantation showed additional restructuring of the smooth muscle cell laye r and more organized epithelialization in comparison to the SIS graft exami ned at 11 days. After 35 days of regenerative healing, elements of all thre e layers of the native ureter were observed within the collagen matrix of t he SIS graft. No significant complications were observed, but all subjects (8/8) demonstrated mild intra-abdominal adhesions. Mild collecting system d ilatations were observed in 4/4 (100%) of the animals harvested at 35 days and in 0/4 (0%) of the animals harvested at 11 days. We have this demonstra ted in this preliminary study that SIS xenografts will epithelialize when u sed as a ureteral replacement material. The repair mechanism of these urete ral grafts occurred through a regenerative healing process rather than by s car formation. With further studies, this material may prove to be a useful treatment option in patients with ureteral injuries.