Expression of vascular endothelial growth factor (VEGF) in various compartments of the human hair follicle

Hair follicle vascularization appears to be closely related to the processe s involved in hair cycle regulation, in which growth factors, cytokines and other bioactive molecules are involved. In particular, vascular endothelia l growth factor (VEGF), essential for angiogenesis and vascular permeabilit y, may be responsible for maintaining proper vasculature around the hair fo llicle during the anagen growth phase. The aim of our study was to compare the in vitro angiogenic capacity, i.e. the steady-state expression of the V EGF gene, of different cultured cell types derived from normal human hair f ollicles, corresponding to different follicular compartments. Human dermal papilla cells (DPC), fibrous sheath fibroblasts, dermal fibroblasts, and fo llicular and interfollicular keratinocytes were cultured and studied in vit ro for VEGF expression at the mRNA level using RT-PCR, and for VEGF protein synthesis by radioimmunoprecipitation and immunocytochemistry. In vivo exa mination for VEGF expression in human terminal hair follicles was performed using immunohistochemical methods. In the present report the expression of four different VEGF molecular isoforms, differing in their angiogenic capa city, are described in different cultured follicular cell types for the fir st time. Cultured follicular cells strongly expressed mRNA of four VEGF mol ecular species identified as the 121-, 145-, 165- and 189-amino acid splice variants, the most prominent being the 121-amino acid molecule. DPC, and a lso other mesenchymal cells such as fibrous sheath fibroblasts and dermal f ibroblasts, in vivo and in vitro strongly expressed VEGF mRNA and synthesiz ed a 46-kDa VEGF protein, whereas follicular and interfollicular keratinocy tes in vitro expressed lower levels of VEGF mRNA and proteins than mesenchy mal cells. As the highest expression of VEGF was found in DPC, we suggest t hat DPC are mainly responsible for angiogenic processes possibly related to the human hair cycle.