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Fig. 1. KGF is cytoprotective for keratinocytes in vitro and for hair follicle keratinocytes in organ culture. (A,B) Quiescent keratinocytes were pre-treated with KGF or vehicle for 16 hours and 1 hour before the addition of menadione. Results of representative experiments of MTT assays with HaCaT keratinocytes (A) or primary human foreskin keratinocytes (B) are shown. All measurements were performed in quadruplicate and the means ± s.d. are shown. The values obtained with the non-treated cells and the KGF-treated cells without application of the cytotoxic agent were arbitrarily set as 1. This was necessary because KGF affects the survival of starved cells, i.e. although the cell number is the same in the non-treated and the KGF-treated population, the mitochondrial activity is higher in the KGF-treated cell population. (C-F) Human anagen VI follicles were isolated from scalp skin, pre-treated with 20 ng/ml KGF for 12 hours and for one additional hour with fresh KGF, and subsequently incubated with 50 µM menadione. Frozen sections from the treated hair follicles [(C) vehicle treatment; (D) 50 µM menadione; (E) 20 ng/ml KGF; (F) 20 ng/ml KGF and 50 µM menadione], were analyzed by TUNEL staining for the presence of apoptotic cells. DP, dermal papilla; MK, matrix keratinocytes; PM, precortical matrix. (G) TUNEL-positive cells and all cells (excluding the cells in the dermal papilla) were counted and the ratio between both numbers was determined (ctrl, n=10; menadione, n=9; KGF, n=11; KGF+menadione, n=12; n, number of hair follicles). Means ± s.e.m. are shown. Statistical analysis was performed using the Mann-Whitney U test. *P<0.05; **P<0.01.
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