April 2004
Effect of minoxidil on proliferation and
apoptosis in dermal papilla cells of human hair follicle.
Han JH, Kwon OS, Chung JH, Cho KH, Eun HC, Kim KH.
Department of Dermatology, Clinical Research Institute, Seoul National
University College of Medicine, Seoul National University Hospital, 28 Yongon-Dong,
Chongno-Gu, Seoul 110-744, South Korea.
BACKGROUND: Minoxidil has been widely used to treat androgenetic alopecia, but
little is known about its pharmacological activity or about the identity of its
target cells in hair follicles. We hypothesized that minoxidil has direct
effects on the proliferation and apoptosis of dermal papilla cells (DPCs) of
human hair follicle.
OBJECTIVE: To elucidate the mechanism of topical minoxidil
action in terms of stimulating hair growth.
METHODS: We evaluated cell
proliferations in cultured DPCs by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl
tetrazolium bromide (MTT) and measured the expressions of extracellular
signal-regulated kinase (ERK), Akt, Bcl-2, and Bax by Western blot. We also
measured elongation of hair follicles in organ culture.
RESULTS: Minoxidil
significantly increased the proliferation of DPCs. The levels of ERK
phosphorylation and of phosphorylated Akt increased significantly 1 h
post-treatment; percentage increase of ERK phosphorylation was 287% at 0.1
microM and 351% at 1.0 microM of minoxidil, and that of Akt phosphorylation was
168% at 0.1 microM and 257% at 1.0 microM of minoxidil. 1.0 microM of minoxidil
increased Bcl-2 expression over 150%, while 1.0 microM of minoxidil decreased
Bax expression by more than 50%.
Moreover, a significant elongation of
individual hair follicles in organ culture was observed after adding minoxidil.
CONCLUSION: Minoxidil promotes the survival of human DPCs by activating both ERK
and Akt and by preventing cell death by increasing the ratio of Bcl-2/Bax.
We
suggest that minoxidil stimulates the growth of human hairs by prolonging anagen
through these proliferative and anti-apoptotic effects on DPCs.
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