ANDROGEN ACTION IN CULTURED DERMAL PAPILLA CELLS FROM HUMAN HAIR-FOLLICLES

Androgens are major regulators of human hair growth with paradoxically different effects on hair follicles depending on their body site. The y stimulate terminal growth in many regions including the face, have n o effect on eyelashes, but may cause inhibition and balding on the sca lp in genetically disposed individuals. How this occurs is unknown. Ho wever, androgens may act on the hair follicle via the cells of the der mal papilla; these would then influence the other cells of the hair fo llicle by altering the production of regulatory substances such as gro wth factors and/or extracellular matrix components. Therefore, primary lines of dermal papilla cells have been established from androgen-sen sitive hair follicles, such as beard, and control, relatively androgen -independent, non-balding scalp cells and their mechanism of androgen action has been compared. Isolated beard dermal papillae were larger t han those from scalp follicles. Although dermal papilla cells did not respond to in vitro androgens by alterations in growth, androgen-depen dent dermal papilla cells contained higher levels of specific, low cap acity, high affinity androgen receptors than non-balding scalp cells. The ability of the cells to metabolise testosterone to 5a-dihydrotesto sterone in culture also varied in parallel to that predicted from stud ies of hair growth in the 5alpha-reductase deficiency syndrome. These results support the hypothesis that androgens act via the dermal papil la. They also show that dermal papilla cells retain differences in gen e expression in culture which appear to correspond with their androgen ic response in vivo. Further studies of such cells should help elucida te why bald men can grow beards!