Mesenchymal stem cells and JIA

Background Mesenchymal stem cells (MSC) are adult stem cells present in bone marrow (BM), fat and in many other tissues. MSC have strong immunosuppressive qualities in vitro. The immunosuppression seems to work both by paracrine action and cell-cell contact. MSC inhibit NKcells, B-cells, dendritic cells, Th1-cells and activate regulatory T-cells. The presence of floating single MSC in human synovial fluid (SF) is a normal phenomenon and the number of MSC in SF is much lower in RA than in osteoarthritis (OA). SF in RA might be impaired in recruiting MSC to the joint and the proliferation potential of MSC in RA patients could be suppressed by the synovitis or be exhausted as suggested by the decreased telomere length. Administration of additional MSC might therefore have great potential in the treatment of inflammatory arthritis as we and others have shown in different experimental arthritis models.