Joost Peerbooms

20 Chapter 2 Figure 1. Flow diagram of the search process. Outcome Measures This review primarily focused on the platelet count, leukocyte count, platelet enrichment factor ([platelet concentration in PRP]/[platelet concentration in whole blood]), and growth factors (platelet-derived growth factor-AB [PDGF-AB], platelet-derived growth factor-BB [PDGF-BB], transforming growth factor-ß1 [TGF-ß1], vascular endothelial growth factor [VEGF], epidermal growth factor [EGF], fibroblast growth factor-2 [FGF-2], hepatocyte growth factor [HGF], and insulin-like growth factor [IGF]). Furthermore, the preparation protocols (amount of whole blood needed, number of centrifugations, time of centrifugation) and prices of the different PRP separation systems were compared. Search Strategy We searched MEDLINE/PubMed, the Cochrane Central Register of Controlled Trials (CENTRAL), and EMBASE up until March 2017 to identify relevant studies concerning the concentrations of blood components in PRP. There were no constraints based on the publication status. In MEDLINE, the following search strategy was used and modified for other databases: