Transplantation of immortalized bladder epithelial cell lines in denuded mouse bladder.

The temporal and spatial regeneration of denuded mouse bladders was characterized using antibody markers to mucosal and submucosal elements in bladder tissue. Mechanical stripping of bladder mucosa resulted in a plane of cleavage in the submucosa leaving the muscle layers intact. Fully regenerated bladders were observed after 14 to 21 days although submucosal elements showed abnormal vacuolation. Implantation of immortalized epithelial cell line BBN3 into denuded bladders resulted in solid tumor formation while, in contrast, transplantation of MB331 showed cystic structures with no indication of invasion. Confirmation of the epithelial and implanted origin of cells lining the lumina of implanted bladders were shown using different keratin antibodies. The benign behavior of MB331 in vivo is suggestive of a cell line representing a preneoplastic stage in carcinogenesis and demonstrates an approach to assess the in vivo phenotype of cell parameters established in vitro.