Platelet rich plasma therapies: a great potential to be harnessed

Platelet rich plasma (PRP) therapies are a sensitive and controversial topic in Orthopaedics and Sports Medicine. Since the pioneer work by Sanchez et al. This rapid expansion has been possible given their safety profile, i.e. autologous source, and minimal manipulation. This issue of Muscles Ligaments and Tendons Journal gathers the work of basic and clinical researchers with multidirectional inputs, and highlights the relevance of translational research in producing the essential scientific knowledge to design successful therapies. The use of PRP therapies started in the clinics rather than in the laboratories, and the rapidly evolving basic PRP knowledge questions the accuracy of PRP description introduced as MeSH (Medical Subject Headings) in 2007: "a preparation consisting of PLATELETS concentrated in a limited volume of PLASMA. This is used in various surgical tissue regeneration procedures where the GROWTH FAC-TORS in the platelets enhance wound healing and regeneration". Indeed, new proteomic analyses of platelet secretome list several hundreds of proteins, and includes not only GROWTH FACTORS, but also a vast array of molecules including cytokines and chemokines, adhesive proteins, and enzymes: GROWTH FACTOR are in reality just a small subset 2 . PRP science is now so complex that devising an appropriate formulation requires further attention to the host tissue context. To tell the truth, PRP therapies are not always successful. Why some patients respond to PRP therapies while others do not; why the same athlete may heal his tendon in one occasion, and fails to heal another tendon in another occasion, without inter-procedural variations, remains an enigma. It is possible that one PRP formulation is appropriate for certain conditions and not as suitable for others. And it is not only the formulation: the volume and protocol for application may be more important than the formulation per se. Inter-individual differences in PRP quality as well as