Efficacy of Combination Therapy with Apigenin and Synovial Membrane-Derived Mesenchymal Stem Cells on Knee Joint Osteoarthritis in a Rat Model.

Background: Osteoarthritis (OA) is a degenerative joint disease that causes a variety of adverse health effects. Considering the need to identify additional effective therapeutic options for OA therapy, we investigated the effect of co-injection of apigenin and synovial membrane-derived mesenchymal stem cells (SMMSCs) on OA in male rats' knee joints. Methods: The study was performed in 2019 at the Department of Pharmacology, Shiraz University of Medical Sciences, Shiraz, Iran. Anterior cruciate ligament transection (ACLT) was used to induce OA. For three weeks, male Sprague-Dawley rats (eight groups, n=6 each) were treated once-weekly with intra-articular injections of apigenin alone or in combination with SMMSC (three million cells), phosphate-buffered saline, or hyaluronic acid. After three months, the interleukin 1 beta (IL-1β), tumor necrosis factor-alpha (TNF-α), superoxide dismutase (SOD), and malondialdehyde (MDA) levels were measured in the cartilage homogenate. The expression of extracellular matrix (ECM) components including collagen 2a1, aggrecan, IL-1β, TNF-α, inducible nitric oxide synthase (iNOS), transcription factor SOX-9, and matrix metalloproteinases 3 and 13 were assessed using real-time polymerase chain reaction (RT-PCR) analysis. Radiological evaluation and histopathological assessment were used to evaluate the knees. Results: Levels of TNF-α (P=0.009), MDA (P>0.001), and IL-1β (P<0.001) decreased and the level of SOD increased (P=0.004) in the apigenin 0.3 µM with SMMSCs group. RT-PCR analysis indicated that IL-1β in the apigenin 0.3 µM with SMMSCs group reduced significantly (P<0.001). This group also exhibited increased expression levels of SOX-9, collagen 2a1, and aggrecan (P<0.001). Conclusion: Apigenin may have supplementary beneficial effects on cell therapy in a rat model of OA due to its possible effect on the reduction of oxidative stress, suppression of inflammation, and promotion of production of ECM components.