Histologic and functional outcomes of small intestine submucosa-regenerated bladder tissue

BACKGROUND Intestinal bladder augmentation has more disadvantages. One of the most promising alternative methods is tissue engineering in combination with surgical construction. Small intestine submucosa (SIS) is commonly used materials in tissue engineer. The aim of this study is determine the histologic and functional characteristics of SIS as bladder wall replacement in a rabbit augmentation model. METHODS 18 New Zealand adult male rabbits, weight 2.5 ± 0.5Kg, were used in this study. The rabbits were divided into 3 groups of 6 based on the number of days post-operative (A, 4 weeks; B, 12 weeks; C, 24 weeks). All of the animals underwent urodynamic testing under anesthesia before cystoplasty with SIS patch. The cystometrograms were repeated 4, 12, and 24 weeks after surgery with the same method. SIS-regenerated bladder strips (10 × 3 × 3 mm) and normal bladder strips (10 × 3 × 3 mm) from the same bladder were obtained at 4, 12, and 24 weeks for in vitro detrusor strip study. The frequency and amplitude of the strip over 15 min was recorded. The regenerated tissue and normal tissue underwent histologic and immunocytochemical analysis. The results were quantified as optical density (OD) values. RESULTS Histologically, the SIS-regenerated bladders of group C (24 weeks post-operation) resembled normal bladder in that all 3 layers (mucosa with submucosa, smooth muscle, and serosa) were present. In the in vitro detrusor strip study, there were no significant differences in autorhythmicity and contractility between regenerated and normal tissues in group C (p > 0.05). Immunohistochemical analysis indicated that the quantity of A-actin grew to a normal level. Urodynamic testing showed that compliance remained stable in all groups post-operatively, and the volume increased 24 weeks post-operatively. CONCLUSION Regenerated tissue has similar histologic and functional characteristics. SIS seems to be a viable material in the reconstruction of the rabbit urinary bladder.