Engineering of multilayered urinary tissue in vitro

Regeneration of the urinary conduit, using engineered autologous material, could have many clinical implications. The urinary system is composed of a three-layered wall consisting of different cell types. In this study we investigated the possibility to coculture these components in vitro into a continuous sheet for total autologous regeneration. To address this issue, human urothelial cells, fibroblasts, and smooth muscle cells were isolated separately and expanded in vitro. Cells were then cocultured by seeding them in layers in a "sandwich model." After coculturing the material was investigated histologically and with immunoassays. The different cells could be cocultured after being isolated and expanded separately in vitro. The cells formed a continuous sheet that could be enzymatically detached and that sustained mechanical handling. The morphology of different cell layers and the reaction to immunostaining indicated their preserved individual phenotype. In conclusion, we showed that human urothelial cells, fibroblasts, and smooth muscle cells can be expanded in vitro and cocultured to form a continuous cellular sheet consisting of three distinct layers of different types of cells. This could provide the surgeon with autologous tissue for urogenital reconstructive purposes.