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Differential effects of caffeine on hair shaft elongation, matrix and outer root sheath keratinocyte proliferation, and transforming growth factor‐β2/insulin‐like growth factor‐1‐mediated regulation of the hair cycle in male and female human hair follicles in vitro
Author(s) -
Fischer T.W.,
HerczegLisztes E.,
Funk W.,
Zillikens D.,
Bíró T.,
Paus R.
Publication year - 2014
Publication title -
british journal of dermatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.304
H-Index - 179
eISSN - 1365-2133
pISSN - 0007-0963
DOI - 10.1111/bjd.13114
Subject(s) - medicine
Summary Background Caffeine reportedly counteracts the suppression of hair shaft production by testosterone in organ‐cultured male human hair follicles ( HF s). Objectives We aimed to investigate the impact of caffeine (i) on additional key hair growth parameters, (ii) on major hair growth regulatory factors and (iii) on male vs. female HF s in the presence of testosterone. Methods Microdissected male and female human scalp HF s were treated in serum‐free organ culture for 120 h with testosterone alone (0·5 μg mL −1 ) or in combination with caffeine (0·005–0·0005%). The following effects on hair shaft elongation were evaluated by quantitative (immuno)histomorphometry: HF cycling (anagen–catagen transition); hair matrix keratinocyte proliferation; expression of a key catagen inducer, transforming growth factor ( TGF )‐β2; and expression of the anagen‐prolonging insulin‐like growth factor ( IGF )‐1. Caffeine effects were further investigated in human outer root sheath keratinocytes ( ORSK s). Results Caffeine enhanced hair shaft elongation, prolonged anagen duration and stimulated hair matrix keratinocyte proliferation. Female HF s showed higher sensitivity to caffeine than male HF s. Caffeine counteracted testosterone‐enhanced TGF ‐β2 protein expression in male HF s. In female HF s, testosterone failed to induce TGF ‐β2 expression, while caffeine reduced it. In male and female HF s, caffeine enhanced IGF ‐1 protein expression. In ORSK s, caffeine stimulated cell proliferation, inhibited apoptosis/necrosis, and upregulated IGF ‐1 gene expression and protein secretion, while TGF ‐β2 protein secretion was downregulated. Conclusions This study reveals new growth‐promoting effects of caffeine on human hair follicles in subjects of both sexes at different levels (molecular, cellular and organ).