CHARACTERIZATION OF CULTURED NAIL MATRIX CELLS

Background: Cultures of epidermal cells are commonly used to study ski n biology and differentiation. Recently a method to culture nail matri x cells has been established. Objective: We report the biologic charac teristics of nail matrix cells in vitro compared with those of epiderm al keratinocytes. Methods: Human nail matrix cells were isolated and c ultured in defined medium. Electronmicroscopic examination, growth rat e, integrin expression and keratin synthesis pattern were evaluated. I n addition, the cells were cultured in serum-containing medium. Result s: Nail matrix cells appear to be larger than human epidermal keratino cytes and, at the ultrastructural level, they contain a higher euchrom atin/heterochromatin ratio and a lower nucleus/cytoplasm ratio and hav e a higher growth rate. The synthesis of ''hard'' keratins was detecte d at all calcium concentrations. Immunofluorescence analyses showed th e expression of alpha 2, alpha 3, and alpha 6 integrin subunits. When cultured in serum-containing medium, nail matrix cells produced an out growth of epithelium and a spontaneous migration phenomenon associated with a tendency to stratify in a semilunar area that resembles the ar chitecture of the nail matrix. The pluristratified epithelium showed c haracteristic markers of nail differentiation. Conclusion: Culture of nail matrix cells may represent a useful model to study the biologic p roperties of nail structure, alterations in some nail diseases and the effects of drugs.