ANDROGEN-DEPENDENT BEARD DERMAL PAPILLA CELLS SECRETE AUTOCRINE GROWTH FACTOR(S) IN RESPONSE TO TESTOSTERONE UNLIKE SCALP CELLS

Androgens stimulate many hair follicles, e.g., beard, but may cause re gression on the scalp; occipital areas are considered androgen indepen dent. The mesenchyme-derived dermal papilla that regulates the hair fo llicle is considered the site of androgen action. Because hair size ha s been clearly related to dermal papilla size, one of the key function s androgens must regulate is the size of the dermal papilla. This impl ies that androgens stimulate dermal papilla cells to divide or to secr ete autocrine mitogenic factors. As physiologic levels of androgens do not stimulate mitogenesis in cultured dermal papilla cells, this stud y was designed to determine whether dermal papilla cells cultured from human hair follicles with different responses to androgens in vivo, i .e., androgen-dependent beard and androgen-independent nonbalding scal p, produce soluble autocrine mitogenic factors and, if so, whether eit her cell type altered their secretion in response to testosterone in v itro. Conditioned medium was prepared by incubating individual primary lines of cells for 24 h with, and without, testosterone (10(-10)-10(- 5) M), All conditioned media significantly increased [H-3]thymidine in corporation by other dermal papilla cells; trypsin treatment significa ntly reduced the effect. Although both beard and scalp cell conditione d media had a similar stimulatory potential, beard cells incorporated approximately double the [H-3]thymidine of scalp cells, in both types of media. Physiologic levels of testosterone increased mitogenic facto r production by beard, but not scalp cells; only beard cells responded to these factor(s), Testosterone added after conditioning had no effe ct, indicating stimulation was not a synergistic effect of testosteron e and conditioned medium. Thus, both beard and scalp cells release sim ilar autocrine growth factor(s), but their response to these factor(s) is determined by their in vivo origin. Testosterone in vitro stimulat es secretion of an autocrine growth factor(s) by beard, but not scalp cells, to which only beard cells are able to respond, reflecting the r esponses to androgens in vivo, These factors may be involved in the ke y increase of dermal papilla size necessary for androgen-induced chang es in hair size.