Summary of the biochemical interactions in wound healing

• bleeding and clotting lays down a matrix of fibrin

• clot is crosslinked by factor XIII, which also links fibronectin (which is an extracellular molecule made by macrophages) to fibrin. fibroblasts are stimulated to divide by PDGF, which is produced by platelets and macrophages

• more fibronectin is synthesized. as it is crosslinked to fibrin, it makes a chemotactic pathway for fibroblasts to crawl along to drag wound edges together. this causes wound contraction

• fibroblasts synthesize type III collagen, which condenses on fibronectin and is ultimately digested by macrophages. this leads to type I collagen, the ultimate form of collagen remaining after the clot has been dissolved

Category: Pathology Notes