A model of superficial bladder cancer using fluorescent tumour cells in anorgan-culture system

Objective To develop a reproducible in vitro simulation of superficial blad der cancer for testing cytotoxic agents at clinically relevant concentratio ns. Materials and methods Square explants (5 mm) of rat bladder were cultured i n Petri dishes in minimal volumes of Waymouth's MB 752/1 medium supplemente d with 10% fetal calf serum, antibiotics and glutamine. Parental and resist ant MGH-U1 urothelial cancer cells were transfected with a green fluorescen t protein (GFP) vector. Transfectants were purified by flow cytometry. Cell s were seeded onto the prepared organ cultures and images obtained using co nfocal microscopy. The tumour colonies were confirmed using scanning electr on microscopy. Conventional intravesical cytotoxic agents including epirubi cin, mitomycin-C and estramustine were tested in the system. Results Colonies of GFP-MGH-U1 cells became established on the explants and were identified by confocal microscopy; the development of the colonies wa s then followed over several days. Staining the explant for viability allow ed imaging of normal urothelium on the explant surface or surrounding skirt of urothelial cells. The conventional cytotoxic agents epirubicin, mitomyc in C and estramustine showed the expected differential responses to parenta l and resistant cell types. The colonies were able to survive high concentr ations of the drug, equivalent to those in clinical use. The colonies were imaged serially over a period of several days. Conclusion This system provides a more realistic model for testing cytotoxi c agents for use in intravesical therapy, by allowing clinically relevant c oncentrations of drugs to be tested. The differential properties of the par ental and resistant cells are maintained. The model also enables the same t umour colony to be imaged over several days in culture. The model may also be adapted for use in testing the effects of drugs on normal urothelium and the study of the effects of growth factors.