Control of proliferation of human fetal adrenal cells in vitro.

The influence of fibroblast growth factor (FGF) and epidermal growth factor (EGF) on the proliferation of cultured human fetal adrenal cells has been examined. Separated human definitive zone and fetal zone adrenal cells plated at low density in the presence of 10% serum and maintained on plastic culture dishes proliferated slowly. If the cultures were exposed to either FGF or EGF, the growth rate of the cells from each zone increased significantly. Half-maximal stimulation of cell proliferation for both zones occurred at a concentration of 3 X 10(-11) M for EGF and 8 X 10(-9) M for FGF. In addition, 125I-labeled EGF binding to both definitive and fetal zone cells demonstrated high affinity (Kd = 10(-9) M). To investigate the influence of an extracellular matrix (ECM) on cell proliferation, separated fetal adrenal cells maintained on plastic culture dishes were compared with cells maintained on a recently described ECM prepared from bovine corneal endothelial cells. Fetal adrenal cells maintained on the ECM had a significantly higher growth rate than cells maintained on plastic alone. These results demonstrate 1) the mitogenic role of EGF and FGF for human fetal adrenal cells, and 2) that the type of substrate upon which fetal adrenal cells are maintained has a profound influence on their proliferation.