HUMAN EPIDERMAL-KERATINOCYTES ARE A SOURCE OF TENASCIN-C DURING WOUND-HEALING

Tenascin-C is a large hexameric extracellular matrix glycoprotein that is expressed in a temporally and spatially restricted pattern associa ted with stromal-epithelial interactions, In adult human skin, the exp ression level of tenascin-C is low, but tenascin-C is abundantly prese nt in the dermal compartment during embryogenesis and wound healing an d in skin tumors. Herein we have investigated the cellular source of t enascin-C production in human skin, both in vivo and iii vitro, by usi ng immunohistochemistry, mRNA in situ hybridization, western blotting, and an enzyme-linked immunosorbent assay, In addition we studied the cell-matrix interaction between epidermal keratinocytes and purified t enascin-C. By using in vitro culture models, we found that keratinocyt es not only synthesize and secrete tenascin-C but can also deposit ten ascin-C in de-epidermized dermis in a pattern that is very similar to that in vivo. In vivo, during wound healing of normal human skin, we f ound tenascin-C extracellularly in the wound bed and also in a granula r pattern within the neo-epidermis. By mRNA in situ hybridization, we could identify the basal migrated keratinocytes as the main source of tenascin-C in the early phase of wound healing. In the granulation pha se, tenascin-C expression by the keratinocytes is downregulated. Cultu red keratinocytes were found to adhere poorly to tenascin-C, and those that did adhere retained a rounded morphology, We conclude that human keratinocytes are a major source of tenascin-C during the early phase of wound healing, and we hypothesize that tenascin-C is unlikely to b e an adhesive substrate for migrating keratinocytes.