In general, growth factors increase chemotaxis and cell mitosis, though each growth factor acts in a distinct way. For example, platelet derived growth factor (PDGF) stimulates collagen synthesis, increases chemotaxis in fibroblasts, macrophages, and neutrophils while increasing mitosis in mesenchymal stem cells. Transforming growth factor beta (TGF-β) stimulates angiogenesis, collagenase secretion, mesenchymal stem cell proliferation, and mitogenesis in osteoblasts, fibroblasts and endothelial cells. Vascular endothelial growth factor (VEGF) increases vessel permeability and angiogenesis, by stimulating mitogenesis in endothelial cells.³ Growth factor release initiates a healing cascade which has downstream effects up to 7 days after administration. Delivering a higher concentration of platelets increases tissue repair leading to better patient outcomes.