Leukocyte poor PRP
In-vitro research has indicated that leukocytes in a PRP preparation had a negative correlation with matrix synthesis and a positive correlation with matrix catabolism in tendons. A higher concentration of leukocytes, therefore, is likely undesirable for musculoskeletal applications associated with tendon healing but could be more relevant for other uses, such as healing of large, infected dermal lesions.
There has been very little in-vivo research on leukocyte content in PRP as a key parameter. PRP with leukocytes produce elevated levels of TGF (improves collagen synthesis), PDGF (increase cell activity in early healing) and VEGF (promotes angiogenesis). Leukocytes also produce cytokines, which can increase pain and reduce healing times. All studies have been completed in-vitro and optimal leukocyte balance remains inconclusive.
Significant research efforts are being directed to the ideal 'PRP recipe' and this includes assessment of Red Blood Cell (RBC) and Leukocyte effect on PRP outcomes. Current research findings are favouring a leukocyte-poor, RBC-free formulation of PRP for intra-articular injections and chronic tendon pathologies.