Immunomodulatory properties of mesenchymal stem cell in experimental arthritis in rat and mouse models: A systematic review

Background Despite recent advances in the treatment of arthritis with the development of disease-modifying antirheumatic drugs, 30% of patients still fail to respond to treatment. Given the potent anti-inflammatory and immunomodulatory properties of mesenchymal stem cells (MSC) and their ability to repair damaged cartilage, bone, and tendons, it has been proposed that MSC could be ideal for cell-based treatment of arthritis. Objective This systematic review investigates evidence from studies on the therapeutic efficacy of MSC in rodent models of arthritis. Methods PubMed, Embase, MEDLINE, and Wed of Science were searched to June 2015 for quantitative studies examining the outcome of treating animal models of arthritis with MSC. Inclusion criteria were as follows: administration of mesenchymal stem as a treatment approach for arthritis; animal models only; and published in English. We followed the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. Results The literature search identified 30 studies which met the inclusion criteria. A range of MSC populations were assessed in various rodent models of arthritis. Of these, 19 demonstrated positive outcomes while 11 studies failed to demonstrate positive effects. Owing to the extensive variation in the experimental design, cells investigated and the outcome measures described in the manuscripts, no meta-analysis was possible. Furthermore, the numerical values for the primary outcome measure of clinical paw score were frequently not published in the manuscripts analyzed, as they were only illustrated in graphical form. Conclusions Numerous studies have investigated the utility of a range of MSC populations in the treatment of experimental arthritis. The results obtained from these studies have been highly inconsistent, with multiple studies identifying a statistically significant improvement in arthritis scores after treatment with MSC, while other studies identified a statistically significant deterioration in arthritis scores and thirdly some studies showed no effect. Further studies using standardized protocols and outcome measures are needed to determine fully the potential of MSC populations in the treatment of experimental arthritis.