Distribution of fibronectin during wound healing in vivo

The distribution of fibronectin during wound healing has been studied. Full thickness wounds were made in the skin on the sides of guinea pigs' trunks. Biopsy specimens were taken from the normal skin, from the 5-hr-old wound, and on days 1-18 after wounding. Unfixed frozen sections were analyzed for fibronectin distribution by indirect immunofluorescence analysis with a specific antiserum prepared in rabbits against guinea pig plasma fibronectin. Tissue samples were also embedded in methacrylate and sections cut and stained with hematoxylin and eosin for general histology or with a silver stain for reticulin. Fibronectin was prominent in the basement membranes of normal skin epidermis. It was also present in the papillary dermis and to a lesser extent in the reticular dermis. After wounding, fibronectin was part of the fibrin clot and distributed along fibrin strands. Fibronectin was also deposited along newly synthesized collagen in the granulation tissue, which was at least in part collagen type III based upon staining for reticulin. Eventually, the entire granulation tissue was transformed into aligned collagen fibrils coated with fibronectin. Throughout the period of wound healing, the level of fibronectin associated with what appeared to be type I collagen in the reticular dermis adjacent to the wound area stayed about the same. When fibrils with the histological characteristics of type I collagen were within the granulation tissue, however, they were coated with fibronectin. The results indicate that fibronectin is a major component present during wound healing.