Efficacy of mesenchymal stem cells injection for the management of knee osteoarthritis: a systematic review and meta-analysis

Objective The purpose of this study was to access the efficacy of mesenchymal stem cells (MSCs) injection in the treatment of knee osteoarthritis (OA). Methods Studies were identified from databases (Pubmed, Embase, Cochrane Library, Biosis Previews, ClincalTrials.gov, CBMdisc) searched to December 2014 using a battery of keywords. We included randomized controlled and controlled clinical trials of people with knee OA comparing the outcomes of pain and function for those receiving MSCs injection with those receiving no MSCs injection. Two reviewers independently selected studies, extracted relevant data and assessed study quality. Data were pooled and meta-analyses were performed. Results Seven randomized controlled and controlled clinical trials, studying a total of 314 participants with a diagnosis of knee OA were included. Overall, MSCs injection has no significant effect on pain [weighted mean difference (WMD) (95 % confidence interval (CI)) [-1.33(-3.08, 0.41), P = 0.13], and tends to improve self-reported physical function [standardized mean difference (SMD) (CI) = 2.35(0.92, 3.77), P = 0.001] at the last follow-up. But results from two high quality trials (94 patients) show a positive effect of MSCs injection on pain [WMD(CI) = -0.49 (-0.79, -0.19), P = 0.001]. Heterogeneity observed between studies regarding the effect of MSCs injection on pain and function was explained by the difference of follow-up time, outcome measures, control group, the source and dose of MSCs. The quality of evidence supporting these effect estimates was rated as low. Conclusion MSCs injection could be potentially efficacious for decreasing pain and may improve physical function in patients with knee OA. The findings of this review should be confirmed using methodologically rigorous and adequately powered clinical trials.