Assessments of Therapeutic Effects of Platelet-rich Plasma in Knee Osteoarthritis: Possible Role of Inflammatory Cytokines

Abstract Background: Osteoarthritis (OA) is a multifactorial disease that commonly affects the knee. Tumor necrosis factor-α (TNF-α) is able to regulate inflammation in OA. Macrophage migration inhibitory factor (MIF) may be involved in the pathophysiology of arthritis. Platelet-rich plasma (PRP) may reduce pain associated with OA. The current study aimed to assess the possible therapeutic effects of PRP in patients with knee OA of various severities. Methods: A prospective study was performed on 90 patients were included and categorized into mild (30 cases, moderate (30 cases) and severe (30 cases) knee OA. Three intra-articular (I.A) injections of PRP, 2 weeks a part, were received. Pain score and MRI Osteoarthritis Knee Score (MOAKS) were assessed. Serial synovial fluid cytokines assays in the form of Tumor necrosis factor-α (TNF-α) and Macrophage migration inhibitory factor (MIF), were performed using commercially available ELISA assay kits. The assays were performed pre-injection (S1), two weeks from the 1st I.A injection and two weeks from the 2nd I.A injection (S3) for all included patients. Results: The mean values of pain score and synovial TNF-α and MIF levels were significantly higher levels (S1, pre-injection) among severe OA when compared with both mild and moderate cases, p˂0.05 for all. There were significantly lower pain score and synovial TNF-α and MIF levels at S3 in mild, moderate and severe knee OA when compared with S1 values, p˂0.05 for all. There was significant improvement in synovitis in both mild and moderate cases (p˂0.05 for both). Conclusion: I.A injection of PRP significantly reduces the synovial fluid TNF-α and MIF levels with great therapeutic effects on both synovitis via reducing inflammatory cytokines, and bone marrow lesions mainly for mild knee OA and to a lesser extent for moderate cases.