Leukocyte-Reduced Platelet-Rich Plasma Normalizes Matrix Metabolism in Torn Human Rotator Cuff Tendons

Background: The optimal platelet-rich plasma (PRP) for treatment of supraspinatus tendinopathy has not been determined. Purpose: To evaluate the effect of low- versus high-leukocyte concentrated PRP products on catabolic and anabolic mediators of matrix metabolism in diseased rotator cuff tendons. Study Design: Controlled laboratory study. Methods: Diseased supraspinatus tendons were treated with PRP made by use of 2 commercial systems: Arthrex Autologous Conditioned Plasma Double Syringe System (L-lo PRP) and Biomet GPS III Mini Platelet Concentrate System (L-hi PRP). Tendon explants were placed in 6-well plates and cultured in L-lo PRP, L-hi PRP, or control media (Dulbecco's Modified Eagle Medium + 10% fetal bovine serum) for 96 hours. Tendons were processed for hematoxylin-eosin histologic results and were scored with the modified Bonar scale. Group 1 tendons were defined as moderate tendinopathy (Bonar score <3); group 2 tendons were assessed as severely affected (Bonar score = 3). Transforming growth factor -1 (TGF-1), interleukin-1 (IL-1), interleukin-1 receptor antagonist (IL-1Ra), interleukin-6 (IL-6), interleukin-8 (IL-8), and matrix metalloproteinase-9 (MMP-9) concentrations in PRP media were measured by use of enzyme-linked immunosorbent assay after 96 hours of culture with diseased tendon. Tendon messenger RNA expression of collagen type I (COL1A1), collagen type III (COL3A1), cartilage oligomeric matrix protein (COMP), MMP-9, MMP-13, and IL-1 was measured with real-time quantitative polymerase chain reaction. Results: Leukocytes and platelets were significantly more concentrated in L-hi PRP compared with L-lo PRP. Increased IL-1 was present in L-hi PRP after culture with group 1 tendons. IL-6 was increased in L-hi PRP after culture with group 2 tendons. Both TGF-1 and MMP-9 were increased in L-hi PRP after culture with either tendon group. In L-lo PRP cultures, IL-1Ra:IL-1 in PRP used as media and COL1A1:COL3A1 gene expression were increased for group 1 tendon cultures. Gene expression of MMP-9 and IL-1 was increased in group 2 tendons cultured in L-lo PRP. There was no significant difference in the expression of MMP-13 or COMP in either group of tendons cultured in L-lo PRP or L-hi PRP. Conclusion: L-lo PRP promotes normal collagen matrix synthesis and decreases cytokines associated with matrix degradation and inflammation to a greater extent than does L-hi PRP in moderately degenerative tendons. In severely degenerative tendons, neither PRP preparation enhanced matrix synthesis. Clinical Relevance: L-lo PRP may promote healing in moderately degenerative rotator cuff tendons.