Basal layer of epithelium expresses tenascin mRNA during healing of incisional skin wounds

Tenascin is a large oligomeric glycoprotein of the extracellular matrix that is expressed prominently during embryonic development and wound healing. Previous studies on tenascin expression in wounds have used immunohistochemistry to describe the expression of tenascin in wounds. The present study used in situ hybridization to identify the cells expressing tenascin mRNA in healing wounds. The results demonstrate that the cells of the basal layer of epidermis, migrating over the healing wound, are expressing the mRNA for tenascin. Intense expression was seen during the first three days after wounding, but after seven days, after the epithelium had grown to cover the wound, no tenascin transcripts were seen in epithelial cells. The epithelial cells elsewhere in the skin were devoid of tenascin transcripts at all stages examined. Previously, prominent immunohistological staining for tenascin has been located in wounds below the migrating epithelial cells and it has been thought to be synthesized by stromal cells upon epithelial induction. Our findings in the present study indicate that tenascin is produced by epithelial cells, which apparently are induced to produce tenascin as they migrate after wounding. (C) Munksgaard, 1996