Chrysin and Bone Marrow-derived Mesenchymal Stem Cells Restrain Complete Freund's Adjuvant-induced Arthritis in Wistar Rats via Subsiding Inflammation and Oxidative Stress.

Introduction: Rheumatoid arthritis (RA) is an inflammatory disease that causes significant disability and persistent inflammation. Currently, there are no appropriate treatments for RA other than systemic immunosuppressants, which have a variety of undesirable effects after long-term use. Thus, this study aims to determine the anti-arthritis effect of chrysin (5,7-dihydroxyflavone) and/or bone marrow-derived mesenchymal stem cells (BM-MSCs), separately and combined, on CFA (complete Freund's adjuvant)-induced arthritis in rats as an animal model of RA.

Methods: Male Wistar rats were injected with 100 μL of CFA/rat/day in the paw of the right hind limb for two consecutive days to induce RA. Arthritic rats received chrysin in an oral dose of 100 mg/kg bw each day, BM-MSCs at 1 × 106 cells/rat once per week in complete culture medium into the lateral tail vein, and a combination for 21 days.

Results: The oral administration of chrysin and intravenous injection of BM-MSCs significantly reduced the increased anteroposterior thickness, volume, and circumference of the right hind paw, as well as serum levels of RF, IL-1β, TNF-α, and IL-17, as well as serum MDA level, besides augmenting serum levels of GPx, GST, GSH, and SOD. The arthritic rats treated with chrysin and/or BMMSCs exhibited a significant improvement in the elevated expression levels of IκBα, NF-κB p50, and NF-κB p65 proteins in ankle joint articular tissue. Similarly, the histopathological score and histological sections provided additional evidence of the improvement in arthritic lesions.

Discussion: The treatment with chrysin and BM-MSCs has potential anti-arthritic effects, which may be attributed to their abilities to suppress the inflammation and oxidative stress and enhance the antioxidant defense system. The combinatory effect of chrysin and BM-MSCs was found to be the most effective. However, further clinical studies are required to assess their safety and efficacy in patients with arthritis.

Conclusion: Due to their strong antioxidant and anti-inflammatory properties, the combined administration of chrysin and BM-MSCs was found to be more effective in treating arthritis than either treatment alone in Wistar rats.