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Long‐term passages of human clonal mesenchymal stromal cells can alleviate the disease in the rat model of collagen‐induced arthritis resembling early passages of different heterogeneous cells

Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease of unknown cause. The interaction of immune system cells and the secretion of inflammatory cytokines with synovial cells leads to severe inflammation in the affected joints. Currently, medications, including non‐steroidal anti‐inflammatory drugs, glucocorticoids, and more recently, disease‐modifying anti‐rheumatic drugs, are used to reduce inflammation. However, long‐term use of these drugs causes adverse effects or resistance in a considerable number of RA patients. Recent findings revealed the safety and efficacy of mesenchymal stromal cells (MSCs)‐based therapies both in RA animal models and clinical trials. Here, the beneficial effects of bone marrow‐derived heterogeneous MSCs (BM‐hMSCs) and Wharton jelly‐derived MSCs (WJ‐MSCs) at early passages were compared to BM‐derived clonal MSCs (BM‐cMSCs) at high passage number on a rat model of collagen‐induced arthritis. Results showed that systemic delivery of MSCs significantly reversed adverse changes in body weight, paw swelling, and arthritis score in all MSC‐treated groups. Radiological images and histological evaluation demonstrated the therapeutic effects of MSCs. There was a decrease in serum level of anti‐collagen type II immunoglobulin G and the inflammatory cytokines interleukin (IL)‐1β, IL‐6, IL‐17, and tumor necrosis factor‐α in all MSC‐treated groups. In contrast, an increase in inhibitory cytokines transforming growth factor‐β and IL‐10 was seen. Notably, the long‐term passages of BM‐cMSCs could alleviate RA symptoms similar to the early passages of WJ‐MSCs and BM‐hMSCs. The importance of BM‐cMSCs is the potential to establish cell banks with billions of cells derived from a single donor that could be a competitive cell‐based therapy to treat RA.