Background and objectives: Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic progressive joint inflammation with subsequent cartilage destruction. This study was conducted to evaluate and compare the effect of bone marrow mesenchymal stem cells (BM-MSCs) versus Methotrexate (MTX) on knee joint in a rat model of RA.
Materials and Methods: Thirty-five adult male albino rats were divided into two groups. Group I: control group (15 rats). Group II (20 rats) in which RA was induced, and then the rats were subdivided into four subgroups. Subgroups IIa and IIb were sacrificed two and four weeks after induction of RA respectively. Subgroups IIc and IId were treated by MTX and BM-MSCs respectively after two weeks of induction of RA and were sacrificed after further two weeks. The knee joints were collected, decalcified and processed for histological, histochemical, immunehistochemical and morphometric studies.
Results: Histological examination of the knee joints revealed that RA resulted in thickening of the intimal lining of the synovial membrane, infiltration, congestion and increased collagen content of the subintima. The articular cartilage showed erosions, thinning, cell and ground substance loss and increased expression of inducible nitric oxide synthase (iNOS). Injection of BM-MSCs resulted in improvement of the structure of the synovial membrane and the articular cartilage of the knee joint whereas, injection of MTX was relatively less effective.
Conclusion: Intra- articular injection of BM-MSCs resulted in a significant improvement in the histological structure of the knee joint in comparison to MTX in a rat model of RA.