RESUMEN
Osteoarthritis (OA) is the most prevalent arthropathy in sport horses. The administration of a platelet lysate (PL) is an alternative method for the treatment of musculoskeletal conditions. The mechanisms by which PL exerts its beneficial effects have not been determined, and less is known about its effect on the activity of the proteolytic enzymes of the synovial fluid of equines with OA. In this work, the effect of the administration of PL to horses with OA was analyzed both clinically and molecularly by determining the levels of matrix metalloproteinase-2 (MMP-2), matrix metalloproteinase-9 (MMP-9), a disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS-5), glycosaminoglycans (GAGs), and tissue inhibitor of metalloproteinase 1 (TIMP-1) in synovial fluid. One mL of PL was administered intra-articularly followed by the extraction of synovial fluid on days 0, 10, 30, and 60. Results were evaluated by an analysis of variance for repeated measures. The levels of MMP-9 decreased significantly (P < .05) on day 10 after treatment with PL. A disintegrin and metalloproteinase with thrombospondin motifs 5 decreased significantly on days 10 (P < .05), 30 (P < .05), and 60 (P < .01) after treatment. The levels of synovial TIMP-1 increased significantly on day 30 (P < .001) after treatment. Glycosaminoglycans showed a significant increase on days 10 (P < .05) and 30 (P < .01). A significant decrease was found for MMP-2 on day 10 (P < .01), 30 (P < .01), and 60 (P < .001). In conclusion, the beneficial effects of PL in OA could be attributed to the decreased activity of MMP-2, MMP-9, and ADAMTS-5 and the increased concentration of GAGs and TIMP-1 after the administration of platelet-rich plasma.