Interactions between steroid-producing cells and capillary endothelial cells in the adrenal gland.

Adrenocortical capillary endothelial (ACE) cells showed a two- to three-fol d increase in number when they were cocultured with bovine adrenocortical ( BPIC) cells from the zona fasciculata-reticularis. This effect was detectab le within 48 h, persisted throughout the seven-day coculture period and occ urred in the absence of addition of exogenous growth factors. It was simila r to that obtained by addition of 1 ng/ml of FGF-2. Adrenal cortex tumor ce lls from humans (NCI) and mice (YI) also stimulated ACE cell growth, wherea s NIH 3T3 cells did not, suggesting an effect specific of steroid-producing cells. Addition of an FGF-2-neutralizing antibody failed to inhibit the BA C cell-induced ACE cell growth stimulation, indicating that FGF-2 was not i nvolved. BAC cell-conditioned medium stimulated ACE cell growth, indicating a role for a diffusible factor. When BAC cells were cocultured with ACE ce lls in a 3D collagen gel, capillary-like tubes developed, consistent with s ecretion by BAC cells of angiogenic factors. Studies are under way to ident ify these factors.