Tinkering with Blood: Optimizing the Coagulation System for Therapeutic Purposes

Blood is a multitask, fluid tissue that is considered as an endless goldmine for regenerative therapies. This connective tissue carries myriad multidomain proteins as the workhorse of biological functions integrated in complex molecular networks. Among them, the coagulation system stands out, with platelets and plasma coagulation proteins playing multiple roles in clotting, defense and tissue repair, the latter of which is the final byproduct process stemming from the hemostatic-inflammatory, cell-reprogramming and inflammation resolution after a tissue injury. By mimicking coagulation and hemostasis but lacking inflammatory properties, platelet-rich plasma (PRP) is emerging as an innovative autologous therapy operating as a local delivery system of growth factors. Processing of the patient blood to manufacture PRP encompasses blood anticoagulation; blood deconstruction through centrifugation and fractionation; and activation of plasma, endowing the applied product with anti-inflammatory, trophic, antifibrotic and antialgic properties in a context-dependent manner. However, the field of PRPs faces controversies due to the heterogeneity of their biological compositions and modalities of application. Moreover, there are some drawbacks derived from patient age and some other conditions, all impinging negatively on PRP clinical outcomes. Standardization of the manufacturing process, elaboration of guidelines of application and use of allogenic PRPs are emerging as possible solutions to surmount these pitfalls.