Mesenchymal stem cells for the treatment of articular cartilage defects of the knee: an overview of systematic reviews.

There is no consensus on the ideal type, dose, expansion, and differentiation of MSCs for treating knee cartilage defects. Our goal was to perform an overview of systematic reviews regarding the use of MSCs for the treatment of articular cartilage lesions of the knee. The overview of systematic reviews followed the Population (patients aged between 18 and 50 years with traumatic knee articular cartilage lesions), Intervention (MSCs treatment), Comparison (autologous chondrocyte implantation or microfracture), and Outcomes (magnetic resonance imaging or second-look knee arthroscopy) matrix. No language restrictions were applied. We assessed methodological quality, reporting standards, and evidence levels. A total of 529 records were retrieved from six databases. After duplicate removal and eligibility screening, nine systematic reviews were included, and three were updated with recent data. Most reviews suggested a positive effect of MSCs on cartilage regeneration; however, considerable heterogeneity was observed regarding MSC source, preparation methods, and outcome measures. MSCs show promise in the treatment of knee cartilage defects. Nonetheless, due to methodological differences and limited high-quality evidence, no standardized clinical protocol can yet be recommended. Further research is needed to establish consensus and guide clinical applications.