By definition platelet rich plasma is a serum which contains platelets at a higher concentration than whole blood. Successful PRP therapy harnesses the healing capacity of platelets by reintroducing these non nucleated cell fragments into damaged or aging tissues. Platelets are activated in the presence of calcium. The activation process occurs naturally when platelets are exposed to collagen, though certain situations benefit from preemptive activation with calcium chloride. Once activated, platelets degranulate and start to release tiny bioactive molecules known as growth factors. Growth factors signal surrounding cells to increase migration and proliferation. Platelet derived growth factor, vascular endothelial growth factor, insulin growth factor-1 & 2, epidermal growth factor, and transforming growth factor-β act in complex ways to regulate angiogenesis, mesenchymal stem cell mitosis, protein synthesis, osteoblast formation, collagen synthesis, and cartilage regeneration.