[Interactions between steroidogenic cells and capillary endothelial cells in the adrenal gland]

Adrenocortical capillary endothelial (ACE) cells showed a two- to three-fold increase in number when they were cocultured with bovine adrenocortical (BAC) cells from the zona fasciculata-reticularis. This effect was detectable within 48 h, persisted throughout the seven-day coculture period, and occurred in the absence of addition of exogenous growth factors. It was similar to that obtained by addition of 1 ng/ml of FGF-2. Adrenal cortex tumor cells from humans (NCI) and mice (Y1) also stimulated ACE cell growth, whereas NIH 3T3 cells did not, suggesting an effect specific of steroid-producing cells. Addition of an FGF-2-neutralizing antibody failed to inhibit the BAC cell-induced ACE cell growth stimulation, indicating that FGF-2 was not involved. BAC cell-conditioned medium stimulated ACE cell growth, indicating a role for a diffusible factor. When BAC cells were cocultured with ACE cells in a 3D collagen gel, capillary-like tubes developed, consistent with secretion by BAC cells of angiogenic factors. Studies are under way to identify these factors.