Cell kinetics of anagen scalp hairs under physiological and pathological conditions

The cell kinetics of anagen scalp hair bulbs taken by punch biopsies from healthy male volunteers (n = 50) were determined at defined bulbar hair segments using microdissection and DNA flow cytometry. The highest proliferative activity (S phase) was measured within the lower most bulbar segment (14.0%) but decreased to the Auber's segment (7.6%) and to the isthmus segment (5.9%). The results support histoautoradiographic data demonstrating most of the proliferative activity in the hair bulb below the Auber's level [1]. Furthermore, cell kinetic data of dissected anagen hair bulbs segmented at Auber's level from an androgen-sensitive scalp area were studied in male pattern baldness (n = 15, Hamilton IV) and hirsutism (n = 13). The results revealed a significant increase of S phase cells in male pattern baldness (8.9%) compared to healthy males (n = 10, 7.9%) as well as in hirsutism (10.2%) compared to healthy females (n = 10, 7.5%). In hirsutism the percentages of S phase cells ran parallel to the plasma levels of dehydroepiandrosterone sulfate whereas no correlation to testosterone could be proved. Similar, 6 hypothyroid and 6 hyperthyroid patients were studied. In hyperthyroidism an increase of S phase values (10.3%) was found, while it decreased in hypothyroidism (6.1%). A correlation between the height of S phase and plasma triiodothyronine level was noted. Our studies demonstrate that DNA flow cytometry is a suitable method for the evaluation of physiological or hormonal influences on cell cycle kinetics of human anagen hair bulbs in vivo.