Effect of mesenchymal stromal cells for articular cartilage degeneration treatment: a meta-analysis

Background aims. Articular cartilage is an avascular tissue that has limited capacity for self-repair. Mesenchymal stromal cells have been considered as potential candidates for cartilage regeneration. However, clinical results of cartilage formation with the use of these cells need evaluation. We aimed to assess the effect of mesenchymal stromal cell treatment on articular cartilage defects. Methods. We searched PubMed, Embase and the Cochrane Central Register of Controlled Trials with key words including "cartilage," "clinical trial," "mesenchymal," "stromal" and "stem cell" up to December 3, 2014. We selected the controlled trial that used treatment with mesenchymal stromal cells on cartilage injury compared with other treatment. We assessed the results of the meta-analysis by means of the error matrix approach. The outcome measures were ranked as comprehensive evaluation index, highest relevance; unilateral evaluation index, medial relevance; and single evaluation index, lowest relevance. Results. Eleven trials assessing 558 patients were included in the meta-analysis. Stem cell treatment significantly improved the American Orthopedic Foot and Ankle Society Scale (Standard Mean Difference, SMD, 0.91; 95% confidence interval [CI], 0.52 to 1.29). The Osteo-Arthritis Outcome Score was also significantly improved in stem cell treatment (SMD, 2.81; 95% CI, 2.02 to 3.60). Other comprehensive evaluation indexes, such as the American Knee Society Knee Score System (SMD -0.12, 95% CI, -1.02 to 0.78), the Hospital for Special Surgery Knee Rating Scale (SMD, 0.24, 95% CI, -0.56 to 1.05) and the International Knee Documentation Committee (SMD, -0.21; 95% CI, -0.77 to 0.34), appeared to have no significant differences by use of stem cell and other treatments. Overall, there was no obvious advantage regarding the application of stem cells to treat cartilage injury, compared with other treatments. Conclusions. In conclusion, assessment of the comprehensive evaluation index indicated that there were no significant differences after stem cell treatment. However, assessment of clinical symptoms and cartilage morphology showed significant improvement after stem cell treatment.