Effect of Human Mesenchymal Stem Cells on Freund’s adjuvant-induced Rheumatoid Arthritis in Sprague Dawley Rats

Introduction Mesenchymal stem cells (MSC) therapy is a new approach to treat RA. Studies evaluating anti-inflammatory effects of MSCs per RA severity are scarce. Our primary objective was to evaluate anti-inflammatory effects, change in cytokine levels and cartilage regeneration of two different MSC preparations delivered through two different routes of administration in three RA stages: mild, moderate and severe.

Methods Human-derived umbilical cord tissue MSCs (hUCT-MSCs) and human bone marrow-derived MSCs (hBM-MSCs) delivered via intra-plantar and intravenous routes were tested in Freund’s adjuvant-induced arthritis in rats. Arthritis severity was based on the arthritis score (<3=mild, 3=moderate and 4=severe). Assessments included changes in arthritis scoring, paw swelling, haematology parameters, biomarkers (TNFα and IL-10) and histopathology analysis.

Results MSC treatment significantly reduced arthritis scores in all treatment groups. IL-10 levels increased 30 days after treatment with (IP)hUCT-MSCs (P=0.0241), (IV)hUCT-MSCs (P=0.0095) and (IP)hBM-MSCs (P=0.0002). TNF-α levels reduced compared to positive control at 30 days: (IP)hUCT-MSCs (P=0.0060), (IV)hUCT-MSCs (P=0.0003), (IP)hBM-MSCs (P=0.0005), (IV)hBM-MSCs (P<0.0001) and continued through 30-60 days. Microscopic examination showed regenerative changes in animal joints treated with both intra-plantar or intravenous MSCs. Arthritis scores reduced in all RA severity groups while benefits (changes in IL-10 and TNF-alpha) were more pronounced in moderate and severe RA. Haematology parameters remained similar among all animal groups at baseline, 30 days and 60 days indicating safety of MSCs.

Conclusion Treatment with hUCT MSCs and hBM MSCs were safe, well-tolerated and effectively reduced joint inflammation, synovial cellularity and pro-inflammatory cytokine levels in CFA-induced RA rat model.