Fibronectin and tenascin in rat tracheal wound healing and their relation to cell proliferation

To investigate the relationship between cell proliferation and distribution of fibronectin and tenascin during wound healing, light and electron microscopy and immunohistochemistry for fibronectin, tenascin, and 5-bromodeoxyuridine (BrdU) were performed following mechanical injury of rat trachea. Tenascin staining appeared 18 h after curettage, when the percentage of BrdU-positive nuclei was maximal in the epithelium. Once tenascin appeared, the labeling index of BrdU-positive epithelial nuclei decreased rapidly. Distribution of tenascin was restricted to granulation tissue in curetted areas which were covered with regenerating epithelium, while fibronectin stained diffusely in both curetted and non-curetted areas. Analysis of the relative intensity of fibronectin and tenascin staining showed that decreases of fibronectin staining were followed by increasing tenascin staining. It is proposed that fibronectin and tenascin may contribute differently to tissue repair in the trachea by interfering with cell proliferation of epithelial cells and fibroblasts.