Mesenchymal stem cells in knee osteoarthritis treatment: A systematic review and meta-analysis

Stem cells are considered to be one of the greatest potential treatments to cure degenerative diseases. Stem cells injection for knee osteoarthritis is still a relatively new treatment and has not yet gained popularity. The objective of this study is to evaluate the effectiveness, safety and potential of mesenchymal stem cells (MSCs) for knee osteoarthritis treatment. We collected clinical trials using MSCs as treatment for knee osteoarthritis (OA) (Before April 2019), including randomized controlled trials (RCTs), retrospective studies and cohort studies. To evaluate the effectiveness and safety of MSC in knee osteoarthritis treatment, we applied visual analog scale (VAS) score, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and adverse events. We searched PubMed, EMBASE, Cochrane Library, Web of Science and the ClinicalTrials.gov with keywords (Mesenchymal stem cells (MSCs), Knee osteoarthritis, Effectiveness and Safety), and then performed a systematic review and cumulative meta-analysis of all RCTs and retrospective comparative studies. We included fifteen RCTs, 2 retrospective studies and 2 cohort studies including a total of 584 knee osteoarthritis (OA) patients in this study. We demonstrated that MSC treatment could significantly decrease VAS in a 12-month follow-up study compared with controls (P < 0.001). MSC therapy also showed significant decreases in WOMAC scores after the 6-month follow-up (P < 0.001). MSC therapy showed no difference compared with controls (P > 0.05) in adverse events. Based on current evidence, our results suggest that MSCs therapy is effective in relieving pain and improving function in patients with Knee OA. MSCs therapy is also a safe treatment and has great potential as a clinical therapy for patients with knee OA. However, the safety and efficacy must be evaluated with a more rigorous, larger sample size validation in the future before MSCs therapy were large-scale applied in clinical practice. This study provided the best available evidence and a wider perspective to MSCs application in the management of knee OA. MSCs therapy will have great translational potential in the clinical treatment of various degenerative diseases once optimum formula and explicit target population are identified.