FUNCTIONAL-RAT BLADDER REGENERATION THROUGH XENOTRANSPLANTATION OF THE BLADDER ACELLULAR MATRIX GRAFT

Objective To determine the decreased antigenicity of the bladder acell ular matrix graft (BAMG) through xenotransplantation and to assess the in vivo and in vitro functional properties of the rat urinary bladder thus regenerated. Materials and methods After partial cystectomy (>50 %), BAMGs prepared from hamster, rabbit and dog urinary bladders were grafted to male and female Sprague-Dawley rats: 10 control rats underw ent partial cystectomy only. Urinary storage and voiding function were monitored in 15 animals using a specially designed 'micturition cage' and cystometry. After 4 months, organ-bath studies and histological t echniques were used to evaluate bladder regeneration in vitro in the g rafted animals. Results Clinically relevant antigenicity was not evide nt; no animal died from rejection and all bladder wall components rege nerated in all BAMG xenografts. However, the degree and quality of reg eneration varied, Muscularization, peak pressure, and bladder capacity were higher in the hamster BAMG-grafted animals, whereas in vitro con tractility and compliance were best in the dog BAMG-regenerated bladde rs, AU grafted bladders had significantly better capacity and complian ce than the autoregenerated bladders after partial cystectomy alone, C onclusions The present in vivo and in vitro studies show that BAMG-aug mentation cystoplasty can lead to morphological and functional regener ation of the rat bladder, preserving its low-pressure reservoir functi on. Because BAMG-regenerated bladders show functional innervation that is similar to normal bladders, they can work in coordination with the host bladder components, thus generating adequate intravesical pressu re to produce sustained voiding, The decreased antigenicity makes hete rologous BAMG transplants feasible without immunosuppression.