Dai W, Leng X, Wang J, et al. - In this study, the efficacy and safety of intra-articular mesenchymal stromal cells (MSCs) injections were investigated for knee osteoarthritis (OA) treatment. Researchers conducted a systematic literature search in PubMed, Embase, Scopus, and the Cochrane Library through April 2020 to distinguish level I randomized controlled trials (RCTs) that assessed the clinical effectiveness of MSCs vs control treatments for knee OA. Results were examined on an intention-to-treat basis with random-effects models. The meta-analysis included a sum of 13 RCTs. For patients with symptomatic knee OA, intra-articular MSC injection was not found to be superior to placebo in pain relief and functional improvement. Nevertheless, for people with symptomatic knee OA, additional direct testing and combination trials of different types of cells, doses, and the number of injections of MSCs are needed to future enhance clinical decision-making.