Experimental Bladder Reconstruction

Abstract: Reduced urinary bladder capacity is a clinically significant problem. The surgical methods that have been available to treat this, such as urinary diversion or surgically augmenting the bladder by incorporation of intestinal segments, all have serious drawbacks. There is a need to understand how the smooth muscle of the intestine and bladder can interact when brought into close contact surgically, and also to develop methods to reconstruct the bladder without using intestinal segments. The experiments on bladder reconstruction performed in this study ? regeneration after subtotal cystectomy, replacement with bowel segments and matrix grafts ? show that the bladder has a high capacity for regenerative growth. After enterocytstoplasty, nerves from the bladder grow into the intestinal segment, in which ganglionic atrophy appears.This is a possible explanation to the shift in pharmacological properties shown to occur in such segments with time, a phenomenon also found in our experiments. The cystometric findings in animals operated with enterocystoplasty suggest that the bowel segment, at least to some degree, participates in the emptying of the bladder, i.e. the intestinal muscle is functionally integrated into the bladder wall and not merely a passive part during emptying. The findings after subtotal cystectomy show that the rat bladder can produce new, contracting muscle, although with lowered maximal shortening velocity and lowered maximal force production ability compared to controls. The nerves found in the bladder developing after subtotal cystectomy represent growth and branching of pre-existing nerves. The nerves found in the small intestinal submucosa matrix grafts are a continuation of nerve trunks from the bladder reaching the grafts at the suture line. The nerve trunks and muscle bundles in the subtotally cystectomized bladders and in the matrix grafts do not fully attain the growth pattern found in normal bladders.