Joost Peerbooms

18 Chapter 2 ABSTRACT Background: Platelet-rich plasma (PRP) has proven to be a very safe therapeutic option in the treatment of tendon, muscle, bone, and cartilage injuries. Currently, several commercial separation systems are available for the preparation of PRP. The concentrations of blood components in PRP among these separation systems vary substantially. Purpose: To systematically review and evaluate the differences between the concentrations of blood components in PRP produced by various PRP separation systems. Study Design: Systematic review. Methods: MEDLINE/PubMed, the Cochrane Central Register of Controlled Trials (CENTRAL), and EMBASE were searched for studies that compared the concentrations of blood components and growth factors in PRP between various separation systems and studies that reported on the concentrations of blood components and growth factors of single separation systems. The primary outcomes were platelet count, leukocyte count, and concentration of growth factors (e.g., platelet-derived growth factor-AB [PDGF-AB], transforming growth factor-ß1 [TGF-ß1], and vascular endothelial growth factor [VEGF]). Furthermore, the preparation protocols and prices of the systems were compared. Results: There were 1079 studies found, of which 19 studies were selected for inclusion in this review. The concentrations of platelets and leukocytes in PRP differed largely between, and to a lesser extent within, the studied PRP separation systems. Additionally, large differences both between and within the studied PRP separation systems were found for all the growth factors. Furthermore, preparation protocols and prices varied widely between systems. Conclusion: There is a large heterogeneity between PRP separation systems regarding concentrations of platelets, leukocytes, and growth factors in PRP. The choice for the most appropriate type of PRP should be based on the specific clinical field of application. As the ideal concentrations of blood components and growth factors for the specific fields of application are yet to be determined for most of the fields, future research should focus on which type of PRP is most suitable for the specific field. Keywords: platelet-rich plasma; systematic review; concentration; platelets; leukocytes; growth factors