Use of porcine small intestinal submucosa in bladder augmentation in rabbit: long-term histological outcome.

Aim:  To investigate long-term histological features of bladder augmentation using porcine small intestine submucosa (SIS) in a rabbit model. Materials and method:  Sixteen New Zealand rabbits were used. Porcine SIS was provided by a manufactured formation derived from the pig. After partial cystectomy was carried out on the bladder, a single layer of SIS (Cook®-SIS Technology, Cook Biotech Incorporated, West Lafayette, IN, USA) (2 × 5 cm) was sewn to bladder with continuous 5/0 vicryl suture material in a watertight manner. Urinary diversion was not used. The rabbits were killed 12 months later and perivesical fat was removed together with bladder. The 5-μm preparations taken from the samples were stained with haematoxylin–eosin and Mason’s trichrome dye. S-100 and F8 stains were also used for immunohistochemical investigations. Results:  The macroscopic view of bladder was normal. SIS was indistinguishable from normal bladder wall, but the region of the graft had a slight white coloration. Microscopic observations showed the continuity of transitional epithelium of host bladder tissue on SIS material. Detrusor and serosal layers were formed and these layers were indistinguishable from host bladder. Fibroblasts were scattered among the collagen fibrils. New vessel formations were present without lymphatic proliferation. Nerve regeneration was excellent. No inflammation was observed in normal and regenerated bladder wall. Conclusion:  At the end of 12 months, the long-term histological features of bladder augmentation with porcine SIS in a rabbit model, such as presence of new vessel formations, nerve regeneration, collagen and smooth muscle regenerations, which were indistinguishable from original bladder, and the absence of inflammation, showed that SIS seems to be a viable alternative to the use of intestine in bladder augmentation.