Characterization of cultured nail matrix cells.

Abstract

Cultures of epidermal cells are commonly used to study skin biology and differentiation. Recently a method to culture nail matrix cells has been established. We report the biologic characteristics of nail matrix cells in vitro compared with those of epidermal keratinocytes. Human nail matrix cells were isolated and cultured in defined medium. Electron-microscopic examination, growth rate, integrin expression and keratin synthesis pattern were evaluated. In addition, the cells were cultured in serum-containing medium. Nail matrix cells appear to be larger than human epidermal keratinocytes and, at the ultrastructural level, they contain a higher euchromatin/heterochromatin ratio and a lower nucleus/cytoplasm ratio and have a higher growth rate. The synthesis of "hard" keratins was detected at all calcium concentrations. Immunofluorescence analyses showed the expression of alpha 2, alpha 3, and alpha 6 integrin subunits. When cultured in serum-containing medium, nail matrix cells produced an outgrowth of epithelium and a spontaneous migration phenomenon associated with a tendency to stratify in a semilunar area that resembles the architecture of the nail matrix. The pluristratified epithelium showed characteristic markers of nail differentiation. Culture of nail matrix cells may represent a useful model to study the biologic properties of nail structure, alterations in some nail diseases and the effects of drugs.