Published online Dec 31, 2011. doi: 10.5499/wjr.v1.i1.4
Revised: December 13, 2011
Accepted: December 26, 2011
Published online: December 31, 2011
Unlike bone marrow (BM) mesenchymal stem cells (MSCs), whose in vivo identity has been actively explored in recent years, the biology of MSCs in the synovium remains poorly understood. Synovial MSCs may be of great importance to rheumatology and orthopedics because of the direct proximity and accessibility of the synovium to cartilage, ligament, and meniscus. Their excellent chondrogenic capabilities and suggested transit through the synovial fluid, giving unhindered access to the joint surface, further support a pivotal role for synovial MSCs in homeostatic joint repair. This review highlights several unresolved issues pertaining to synovial MSC isolation, topography, and their relationship with pericytes, synovial fibroblasts, and synovial fluid MSCs. Critically reviewing published data on synovial MSCs, we also draw from our experience of exploring the in vivo biology of MSCs in the BM to highlight key differences. Extending our knowledge of synovial MSCs in vivo could lead to novel therapeutic strategies for arthritic diseases.