Vellus Hair Follicle-Derived Keratinocyte Culture: A New Experimental Model in Human Hair Research

Abstract

Biological and biochemical mechanisms of hair growth are difficult to study in vivo; therefore the development of in vitro models is of great interest. Today, we have of our disposal reliable techniques to cultivate cell populations and entire components of terminal hair follicles; however, in vitro culture models for cells derived from vellus hair follicles have not yet been established. In this study, we present a technique for cultivating vellus hair follicle-derived keratinocytes (VHK) and we present first findings on their characterization. Primary cultures of VHK were obtained as outgrowths of cultured intact vellus hair follicles prepared by microsurgical means after incubation of full-thickness human skin with dispase. (1) VHK cultures reached confluency after 16-20 days and 3-4 subcultures were possible. (2) VHK were characterized as epithelial cells by light and electron microscopy. (3) A multi-layered stratified epithelium with 8-10 cell layers was observed by electron microscopy presenting abundant keratinosomes in individual cells in contrast to outer root sheath keratinocytes. (4) Synthesis studies of two glycoproteins characteristic for undifferentiated (gp 38) and for differentiated (gp 80) keratinocytes revealed higher synthesis levels for gp 80 and lower levels for gp 38 in VHK as compared to normal epidermal keratinocytes in vitro. These findings suggest a distinct morphologic and differentiation pattern of VHK in culture. This experimental model provides a new tool to study mechanisms of hair growth regulation in vellus hair follicles and to compare them to those of terminal hair follicles.