Mesenchymal stem cells injections for knee osteoarthritis: a systematic overview

Numerous systematic reviews investigating the effects of mesenchymal stem cells (MSCs) in treating knee osteoarthritis (OA) have been published with controversial conclusion. The purpose of the overview was (1) to perform an overview of systematic reviews investigating MSCs for knee OA and (2) to synthesize evidence qualitatively to assess confidence in the review findings. A systematic search of systematic reviews published through Aug 2017 was conducted using the MEDLINE, EMBASE and Cochrane Library. The methodological quality and risk of bias of included systematic reviews was assessed by AMSTAR instrument and ROBIS tool, respectively. Best evidence choice procedure was conducted according to the Jadad decision algorithm. The systematic reviews with high methodological quality and low risk of bias were selected ultimately for further evidence synthesis based on the CERQual tool. Four systematic reviews were eligible for inclusion. According to the ROBIS tool, there was one systematic review with low risk of bias and three with high risk of bias. Thus, only one systematic review conducted by Pas et al. with highest AMSTAR score and low risk of bias was selected. For all outcomes after evidence synthesis via the CERQual tool, confidence for decision making was either low (self-reported measurement and MRI/histological outcome) or moderate (adverse events). The present study demonstrates that moderate confidence could be placed in safety of MSCs therapy for knee OA, but with low confidence in efficacy outcomes due to limitations of the current evidence. Further high-quality studies with high internal and external validity are still required.