Joost Peerbooms

19 Concentrations of blood components in PRP separation systems INTRODUCTION Platelet-rich plasma (PRP) is a small volume of autologous blood plasma that has been enriched with blood-derived platelets. 21 PRP is considered to have beneficial effects on many healing processes as a result of the growth factors contained in the platelet alpha-granules. 43 The use of PRP for clinical applications in periodontal and oral surgery, maxillofacial surgery, plastic surgery, and the treatment of chronic skin and soft tissue ulcers has been extensively investigated. 22,33,47,53 PRP has proven to be a very safe therapeutic option; complications are rarely reported, as PRP is derived from autologous blood. 42 In orthopaedic surgery and sports medicine, the use of PRP has been of increasing interest over the last decade. PRP has shown to have a beneficial effect on the healing of tendon, muscle, bone, and cartilage injuries. 15,58 Clinical studies on the efficacy of PRP in the treatment of symptomatic knee osteoarthritis 31,39,52 and chronic tendinopathy such as patellar tendinopathy 14,17 and lateral epicondylitis 19,23,40,41 have shown beneficial effects of PRP injections. Currently, several commercial separation systems are available for the preparation of PRP. 15 The concentrations of blood components in PRP (platelets, leukocytes, and growth factors) among these separation systems vary substantially. 15 Studies comparing the differences in blood components in PRP from these separation systems report varying outcomes in terms of the concentrations of blood components and growth factors. 7,36,50 To gain more insight into the differences between the concentrations of blood components and growth factors in PRP produced by the different separation systems, we conducted a systematic review of the literature on studies investigating the blood components and growth factors in PRP. METHODS Inclusion Criteria The literature search performed for this review was limited to studies that compared the concentrations of blood components and growth factors in PRP between different PRP separation systems and studies that reported on the concentrations of blood components and growth factors of single PRP separation systems. We only included studies investigating human blood taken from healthy adult (age > 18 years) volunteers. The literature search was limited to articles in the English, German, French, and Dutch languages. Only studies reporting on PRP separation systems that are currently commercially available were included. 2