Rheumatoid arthritis is an autoimmune, inflammatory, systemic and chronic disease characterized by peripheral synovitis and several extra-articular manifestations. The typical clinical manifestations of rheumatoid arthritis include pain and swelling of the joints (191). Regarding the inflammatory process that typically occurs in rheumatoid arthritis, blood cells and inflammatory mediators migrate into the joints, resulting in synovial hyperplasia. As a result of this process, both the synovial membrane of the diarthrodial joints and other joint structures, cartilage and bone are damaged (191). In addition to the invasion of the entire joint, these pro-inflammatory cells also invade other tissues, such as ligaments, tendons and bone, causing similar lesions (191). The invasion of the cartilage by pro-inflammatory cells leads to degradation of type II collagen by matrix metalloproteinases, and by other enzymes produced by synovial cells and chondrocytes when stimulated by inflammatory cytokines such as TNF-α, IL-1, IL-6, and IL-17, secreted by cells from the inflammatory infiltrate (192). hMSCs were used for the treatment of rheumatoid arthritis in 17 studies (72, 86–97, 152, 153, 157, 158). Among them, 14 (72, 86, 87, 89–94, 96, 152, 153, 157, 158) used mice as the experimental model, three (88, 95, 97) used rats and no study was conducted in humans. Regarding the source of the hMSCs used, the adipose tissue was chosen as the source of hMSCs by the majority of studies analyzed. In a total of seven studies (86, 87, 94, 96, 152, 153, 158) hMSCs were isolated from the adipose tissue while the umbilical cord was used as the source of hMSCs in six studies (89, 91, 93, 95, 97, 158) and in only four studies hMSCs were obtained from the bone marrow (72, 92, 95, 158). Furthermore, hMSC were isolated from the placenta (88), gingival (90) and menstrual blood (72) in one study each. Finally, in one study (157), hMSCs were obtained from the directed differentiation of embryonic stem cells.