Why is PDGF important in wound healing?

Platelet-derived growth factor (PDGF) is a potent mitogen released primarily by activated platelets during the initial phase of wound healing, though it is also secreted by macrophages, endothelial cells, and smooth muscle cells. Its primary role is to stimulate the proliferation and migration of fibroblasts and smooth muscle cells into the wound site, which is essential for the proliferative and remodeling phases of healing. Fibroblasts recruited by PDGF produce collagen and extracellular matrix components that form granulation tissue and ultimately scar tissue, restoring tissue integrity. PDGF also has chemotactic properties, attracting additional repair cells to the wound. It does not prevent clotting; in fact, it is released from platelets that are actively participating in clot formation. It does not directly destroy pathogens — that role belongs to neutrophils and macrophages through phagocytosis and oxidative burst mechanisms. Breaking down clots is the function of the fibrinolytic system, specifically plasmin acting on fibrin, not PDGF. Students should remember PDGF in the context of cellular proliferation and connective tissue repair, making it a key mediator of the healing response after hemostasis is achieved.