Bladder wall replacement by tissue engineering and autologous keratinocytes in minipigs

OBJECTIVE: To develop a tissue-engineered bladder wall replacement with autologous cells and a biodegradable scaffold, as whenever there is a lack of native urological tissue the bladder is reconstructed with different bowel segments, which has inevitable complications. MATERIAL AND METHODS: Skin biopsies were taken from six minipigs, and primary fibroblast and keratinocyte cell cultures established. A partial resection of the urinary bladder was reconstructed by a cell-seeded scaffold covered with completely differentiated epithelium and supported by a mucosa-free pedicled ileum graft. Each pig was assessed urodynamically and by cystography before operation and every month until explantation; the pigs were killed at 1, 2 and 3 months after augmentation. Control groups (of six pigs each) with bladder augmentation with complete or denuded ileum were used. The bladders were assessed histologically and by distensibility measurements RESULTS: The differentiated keratinocyte epithelium was still present on the reconstructed bladder wall after 3 months. The overall shrinkage rate was 6.5%. The engineered bladder wall had lower distensibility than the native one. The inflammatory reaction present initially had disappeared after 3 months. CONCLUSIONS: The implanted, tissue-engineered substitution of the bladder wall is not only a bridging graft, but also a complete reconstruction. With this model, extended bladder wall substitution seems feasible and should be investigated in further studies.