The mechanism of human bladder tumor implantation in an in vitro model.

Implantation of tumor cells in the bladder following transurethral resection of superficial bladder tumors is believed to be one factor in the etiology of bladder tumor recurrences. Using an in vitro model system we have studied the initial interaction between bladder carcinoma cells and a naturally produced basement membrane-like substrate. Minced explants of superficial low grade human bladder tumors from 10 patients were plated into culture dishes coated with a naturally produced extracellular matrix (ECM). This ECM has been shown to resemble the human urothelial basement membrane and submucosa in its macromolecular composition and ultrastructural appearance. It was found that a firm attachment of the human bladder tumor cells occurred within one hour, reached a maximal value within 24 hours and was followed by flattening and proliferation of the plated cells. These results indicate that prevention of tumor implantation should be initiated in the first hour after transurethral resection of the bladder tumors. This assay can be used for the investigation of various treatments to prevent tumor implantation.