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World J Rheumatol. Dec 31, 2011; 1(1): 4-11
Published online Dec 31, 2011. doi: 10.5499/wjr.v1.i1.4
Synovial mesenchymal stem cells in vivo: Potential key players for joint regeneration
Elena Jones, Dennis McGonagle
Elena Jones, Dennis McGonagle, Academic Unit of Musculoskeletal Disease, Leeds Institute of Molecular Medicine, Leeds LS9 7TF, United Kingdom
Author contributions: Jones E and McGonagle D concepted and designed the article, and prepared the mansuccript; Jones E collected, analyzed and interpreted the data.
Supported by Funding from Wellcome Trust/EPSRC through WELMEC, a Centre of Excellence in Medical Engineering, No. WT 088908/Z/09/Z and No. EU FP7; the National Institute of Health Research and an AR UK endowment (to McGonagle D, in part)
Correspondence to: Elena Jones, PhD, Academic Unit of Musculoskeletal Disease, Leeds Institute of Molecular Medicine, Room 5.24 Clinical Sciences Building, St James's University Hospital, Leeds LS9 7TF, United Kingdom.
Telephone: +44-113-2065647 Fax: +44-113-3438502
Received: June 10, 2011
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.

Keywords: Mesenchymal stem cells, Synovium, Fibroblasts, Synovial fluid, Arthritis