Urine from Patients with Transitional-Cell Carcinoma Stimulates Migration of Capillary Endothelial Cells

THE growth of new capillary blood vessels toward a solid tumor is a process that requires both migration and proliferation of capillary endothelial cells.1 As part of our studies of tumor-capillary inter-actions, we have cultured endothelial cells from bovine and human capillaries.2 Using a new quantitative assay for endothelial-cell migration, we found that neoplastic cells release a substance that stimulates the in vitro migration of capillary endothelial cells.3 On the basis of this observation, we postulated that biologic fluids that bathe tumors in vivo may also contain detectable amounts of a factor that stimulates the migration of capillary endothelial cells. . . .