Permissive effect of the extracellular matrix on cell proliferation in vitro

Corneal endothelial cells maintained in tissue culture retain the ability to synthesize and secrete an extracellular matrix (ECM) along their basal cell surface. Treatment of confluent cultures with 0.5% Triton X-100 results in the removal of the cell monolayer, thereby exposing the ECM, which adheres strongly to the tissue culture dish. Dishes coated with ECM were used to study the permissive effect of such a substrate on cell proliferation. The proliferation of bovine granulosa and adrenal cortex cells maintained on plastic tissue culture dishes was compared to that on dishes coated with ECM. Neither cell type, even when exposed to optimal serum concentration, replicated when seeded at low cell density on plastic. In contrast, when seeded on ECM they proliferated actively. None of the cultures maintained on ECM required fibroblast growth factor in order to reach confluence, although when maintained on plastic they were totally dependent on fibroblast growth factor for proliferation. Because cells maintained on plastic do not respond to factors present in serum or plasma, although they do so respond when maintained on ECM, it is likely that the close contact of the cells with the ECM restores their sensitivity to agents present in serum and plasma.