Intra-articular injection of mesenchymal stem cells is safe and effective to alleviate pain and improve the motor function of individuals suffering from knee osteoarthritis in a short term.

A meta-analysis and systematic review were carried to investigate the effects and safety of mesenchymal stem cells on individuals suffering from knee osteoarthritis.

Databases such as Cochrane Library, PubMed, and EMBASE were retrieved. Utilizing the Cochrane Collaborative Bias Risk Tool, an evaluation of the bias risk was done. Using plotting funnel plots and Egger tests, the publication bias was determined. The pain and functional improvements in knee osteoarthritis subjects were assessed by alterations in the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores and visual analog scale (VAS) scores at baseline and the follow-up endpoints.

For assessing MRI, the whole-organ magnetic resonance imaging score (WORMS) and in cartilage volume were used. Furthermore, the number of adverse events in the intervention and the control arm was counted to determine the safety. The study included ten randomized controlled trials involving about 335 patients.

In the pooled assessment, the VAS scores of mesenchymal stem cell groups declined considerably compared to the control groups. Remarkable improvements were noted in the WOMAC scores: the total scores, pain scores, stiffness scores, and functional scores.

Notably, two studies with non-double-blind designs were the major source of heterogeneity. Regarding cartilage repair, there was no vital difference in the WORMS score. However, a considerable rise was noted in the cartilage volume in the mesenchymal stem cell group. The percentage of subjects with adverse events in the mesenchymal stem cells therapy group was considerably greater compared to the control group.

Mesenchymal stem cells may be beneficial to treat knee osteoarthritis as they delay articular cartilage degradation and have a protective effect on cartilage.