The most common autoimmune diseases that affect the joints are osteoarthritis (OA) and rheumatoid arthritis (RA).

The pathogeneses of both OA and RA are complex: in both diseases, initiation and progression are dependent on multiple joint structures, including cartilage, bone, and synovium.

Mesenchymal stem cell (MSC)-based therapies are the most popular new strategy in tissue repair and regeneration, due to their multipotent differentiation abilities. In addition, MSC have therapeutic potential for bone and joint diseases through the secretion of a variety of immune modulatory substances and cell-to-cell interactions that lead to the antifibrotic, anti-apoptotic, proangiogenic, and immunosuppressive properties of the treatment.

Research using MSC in various joint diseases has gained attention and impetus. A significant amount of data has shown the efficacy of MSC treatment in OA and RA, in both animal models and human trials: however, the results are often diverse and clinical benefit varies between trials. The identification of successful therapy requires further research and development, both at the basic biology and translational study levels. In this review, the authors aim to emphasise the role of MSC-based therapies in the development of treatment and to define the mechanisms involved, alongside outlining the knowledge of the therapeutic mechanisms and the applications of MSC in OA and RA.