The safety and efficacy of mesenchymal stem cells in the treatment of COVID-19-associated pneumonia: a systematic review and meta-analysis

Mesenchymal stem cells (MSCs) therapy is considered one of the most promising treatments in the context of the coronavirus disease 2019 (COVID-19) pandemic. However, the safety and effectiveness of MSCs in the treatment of COVID-19-associated pneumonia patients need to be systematically reviewed and analyzed. Two independent researchers searched for the relevant studies published between October 2019 and April 2021 in PubMed, Embase, Cochrane Library, WAN FANG, and CNKI databases. A total of 22 studies involving 371 patients were included in the present study. MSCs were administered in 247 participants, and MSCs were allogeneic from umbilical cord, adipose tissue, menstrual blood, placenta, Whartons jelly, or unreported sources. Combined results found that MSCs group significantly reduced the incidence of adverse events (OR = 0.43, 95%CI. = 0.22[~]0.84, P = 0.01) and mortality (OR = 0.17, 95%CI. = 0.06[~]0.49, P < 0.01), and the difference compared with control group was statistically significant. No MSCs treat-related serious adverse events were reported. The lung function and radiographic outcomes, and biomarker levels of inflammation and immunity all showed improvement trends. Therefore, MSCs therapy is an effective and safe method in the treatment of COVID-19-associated pneumonia and shows advantages in less adverse events and mortality. However, a standard and effective MSCs treatment program needs to be developed.