In Situ Autologous Bladder tissue culture for Bladder Autoaugmentation in Animal Model: Bladder wall as A Bioreactor

Abstract

PURPOSE To introduce a new technique for bladder autoaugmentation using in situ autologous bladder tissue culture and expansion for augmentation cystoplasty in a rabbit model and report its preliminary surgical outcome. MATERIAL AND METHODS Twenty-four rabbits were divided into 3 groups. Group I underwent classical autoaugmentation. Group II underwent insertion of tissue expander in a 2x1 cm 2 frame of bladder wall between the mucosa and seromuscular layer for autoaugmentation marked by non-absorbable sutures. In group III all animals were allocated the same technique although the inserted tissue expander was implanted with autologous tissue fragments. In this group a 10x5 mm 2 full thickness bladder biopsy was dissected and separated smooth muscle cell (SMC) and urothelial cell (UC) tissue layers were minced into 20 fragments. The SMC fragments were coated on the separated mucosal layer beneath the tissue expander and UC fragments were seeded on the expander under the seromuscular layer. After 6 weeks the 2 recombinant bladder tissue layers were grafted to the remaining host bladder. Immediately before grafting and at 30 d intervals after grafting, bladder biopsies were obtained for determination of CD31/34, SMC α-actin, and cytokeratin AE1/AE3 following cystometric evaluations. RESULTS The bladder wall frames containing fragment-seeded tissue expanders, demonstrated organized bladder wall generation in two different expanded layers with mature urothelium and muscular layers. While number of CD34+ endothelial progenitor cells and CD31+ microvessels were significantly higher(P <0.05). Group III showed a significant bladder capacity increment as compared with groups I-II (P <0.001). CONCLUSIONS Our RESULTS demonstrate the bladder wall acted as an in situ bioreactor; preserved autologous bladder tissue culture with seeded fragments on a tissue expander provided a histologically organized bladder wall generated in vivo, adding 2 times more surfaces applicable in augmentation.