Synchronous appearance of fibronectin, integrin alpha 5 beta 1, vinculin and actin in epithelial cells and fibroblasts during rat tracheal wound healing.

The distribution of integrin alpha 5 beta 1 (alpha 5 beta 1) and associated components during wound healing was investigated in the rat trachea following mechanical injury. Under anesthesia, the ventral surface of the trachea was scratched, and tissue specimens were obtained from 6 h to 3 weeks after injury and studied using light and electron microscopy and immunohistochemistry. alpha 5 beta 1, vinculin and actin in regenerating epithelial cells and extracellular fibronectin appear virtually simultaneously after injury (from 12 h to 7 days) as do alpha 5 beta 1, vinculin and alpha-smooth muscle actin in fibroblasts and cellular fibronectin in granulation tissue (from 3 to 10 days). Immunoelectron microscopy 2 days after injury showed that alpha 5 beta 1 and vinculin were localized on the basal and lateral surfaces of regenerating epithelial cells and fibroblast surfaces, and fibronectin was localized just under the regenerating epithelial cells, around collagen fibrils and sporadically around fibroblasts. Bromodeoxyuridine labeling showed that the appearance of these components was associated with the period of cell proliferation. The appearances of fibronectin, alpha 5 beta 1, vinculin and actin in regenerating epithelial cells and fibroblasts during tracheal wound healing are well coordinated. During the initial cell migration phase, plasma fibronectin may stimulate cell migration before cellular fibronectin is produced in situ, and regenerating epithelial cells appear to begin to migrate into the wound before cell proliferation starts.