Interaction between dermal papilla cells and follicular epithelial cells in vitro: effect of androgen

To investigate the mode of action of testosterone on human hair follicles, we studied the localization of androgen receptors in hair follicles and cultured dermal papilla cells from different body sites, using immunohistochemistry with a polyclonal antibody. Androgen receptors were detected in the dermal papilla cells of beard and axillary hair follicles, but not in those of occipital scalp hair follicles. Epithelial cells of the hair follicles were not stained by the antibody. Androgen receptors were also detected in the nuclei of cultured beard and axillary dermal papilla cells, but the dermal papilla cells from occipital scalp hair follicles showed little staining with this antibody. We also examined the effects of testosterone on the DNA synthesis and proliferation of cultured outer root sheath cells and dermal papilla cells. Testosterone did not have a proliferative effect on either type of cell when cultured alone. In contrast, testosterone significantly stimulated the proliferation of outer root sheath cells which were co-cultured with beard or axillary dermal papilla cells, without cell contact. No such effect was observed when dermal papilla cells from occipital scalp hair follicles were used in the cultures. This proliferative effect of testosterone was concentration-dependent, and was antagonized by cyproterone acetate. Our findings suggest that dermal papilla cells from the beard and axillary hair follicles produce androgen-dependent diffusible growth factors which stimulate follicular epithelial cells.