Platelet-rich plasma (PRP) is blood plasma that has been enriched with platelets. As a concentrated source of autologous platelets, PRP contains several different growth factors and other cytokines that can stimulate healing of bone and soft tissue. As of 2016, no large-scale randomized controlled trials have confirmed the promise of PRP in basic science and preclinical trials to treat musculoskeletal injuries (including tendinitis, nerve injuries), help in bone grafting or androgenic hair loss.
The efficacy of certain growth factors in healing various injuries and the concentrations of these growth factors found within PRP are the theoretical basis for the use of PRP in tissue repair. The platelets collected in PRP are activated by the addition of thrombin and calcium chloride, which induces the release of the mentioned factors from alpha granules. The growth factors and other cytokines present in PRP include: