Androgens are the main regulators of human hair growth. Paradoxically, androgens can convert small vellus hair follicles to long terminal ones as seen during growth of beard and in hirsutism, however they also can stimulate the gradual transformation of large terminal scalp follicles to tiny vellus ones causing androgenetic alopecia in individuals with a genetic predisposition. Hair disorders are poorly controlled and may cause psychological distress and reduction in the quality of life. The molecular mechanisms of androgen action in human hair follicles are not fully understood. However it is believed that androgens exert their effects on hair follicles via the dermal papilla cells by altering the regulatory paracrine factors produced by the dermal papilla itself and affect the other follicular components. The study aimed to identify key paracrine factors which involved in androgen-regulated alopecia. Balding and non-balding scalp hair follicles isolated and analyzed by molecular biological methods, DNA microarray and quantitative real-time PCR. Comparing balding and non-balding follicles from the same individuals revealed the expected reduction in several keratin and keratin-related protein genes supporting this approach’s validity. There were also significant differences in paracrine factors previously implicated in androgen action by in vitro studies. Several factors believed to increase during androgen stimulation of larger, darker follicles, e.g. IGF-I and SCF, and VEGV were lowered in balding follicles, while putative inhibitory factors, e.g. TGFß-1, IL-1β, IL-1α, and IL-6 were increased. These findings increase our understanding of androgen action in human hair follicles; this could lead to better treatments for hair disorders.

hair follicles, androgen, androgenetic alopecia, PCR, microarray