Bladder reconstruction using scaffold-less autologous smooth muscle cell sheet engineering: early histological outcomes for autoaugmentation cystoplasty.

OBJECTIVE: To investigate the feasibility of a new approach for cystoplasty using autologous smooth muscle cell (SMC) sheet and scaffold-less bladder tissue engineering with the main focus on histological outcomes in a rabbit model.

MATERIALS AND METHODS: In all, 24 rabbits were randomly divided into two groups. In the experimental group, SMCs were obtained from the bladder muscular layer, labelled with PKH-26, and seeded on temperature-responsive culture dishes. Contiguous cell sheets were noninvasively harvested by reducing the temperature and triple-layer cell-dense tissues were constructed. After partial detrusorectomy, the engineered tissue was transplanted onto the urothelial diverticulum. The control group underwent partial detrusorectomy followed by peritoneal fat coverage. At 2, 4, and 12 weeks the rabbits were humanely killed and haematoxylin and eosin, Masson's trichrome, cluster of differentiation 34 (CD34), CD31, CD3, CD68, α-smooth muscle actin (α-SMA), picrosirius red, and pentachrome staining were used to evaluate bladder reconstruction.

RESULTS: At 2 weeks after SMC-sheet grafting, PKH-26 labelled SMCs were evident in the muscular layer. At 4 weeks, 79.1% of the cells in the muscular layer were PKH-positive cells. The portion of the muscular layer increased in the experimental group during the follow-up and was similar to normal bladder tissue after 12 weeks. α-SMA staining showed well organised muscle at 4 and 12 weeks. CD34+ endothelial progenitor cells and CD31+ microvessels increased continuously and peaked 4 and 12 weeks after grafting, respectively.

CONCLUSION: In the present study, we show that autologous SMC-sheet grafting has the potential for reliable bladder reconstruction and is technically feasible with a favourable evolution over the 12 weeks following implantation. Our findings could pave the way toward future bladder tissue engineering using the SMC-sheet technique.