The growth of WI-38 cells in a serum-free, growth factor-free, medium with elevated calcium concentrations.

The growth of WI-38 cells in serum-free growth medium with and without hormone supplementation in the presence of elevated Ca2+ concentrations was investigated. At 5 mM CaCl2, WI-38 cells seeded at low density without serum or hormone supplementation showed up to a 12-fold increase in cell number at saturation density over that obtained at day 1. Saturation densities were comparable when either 5 mM CaCl2 or epidermal growth factor (1 mM CaCl2) was used in the presence of insulin, dexamethasone and transferrin. Combining suboptimal doses of epidermal growth factor and CaCl2 resulted in an additive effect on saturation density. Thus, normal human diploid cells are capable of substantial growth in serum-free, hormone-free growth medium. In contrast, confluent cultures refed with the same medium are not responsive to elevated Ca2+ concentrations. In fact, elevated Ca2+ concentrations inhibited the proliferative response of confluent cultures to epidermal growth factor, but enhanced their response to the combined treatment of insulin, transferrin and dexamethasone.