STIMULATION OF ENDOTHELIAL CELL-PROLIFERATION BY PRECURSORS OF THYMIDYLATE

Bovine corneal and aortal endothelial cell cultures were established from primary explants and subcultured for at least 40 passages. With both cell lines, exogenous thymidine, folate or folinate markedly increased the proliferation of these cells and decreased their serum requirement in Medium 199. Medium 199 supplemented with thymidine enhanced cell survival at low densities; clones were readily produced when single cells were plated as low as 0.07 cells/cm2. Neither fibroblast growth factor nor epidermal growth factor were necessary for cell proliferation or survival at low densities.