Treatment with human umbilical cord-derived mesenchymal stem cells for COVID-19 patients with lung damage: a randomised, double-blind, placebo controlled phase 2 trial

Objective To assess the safety and efficacy of human umbilical cord-derived MSCs (UC-MSCs) for severe COVID-19 patients with lung damage. Design, Multicentre , randomised, double-blind, placebo-controlled trial. Setting Two hospitals in Wuhan, China, 5 March 2020 to 28 March 2020. Participants 101 severe COVID-19 patients with lung damage aged between 18-74 years. Intervention Patients were randomly assigned at a 2:1 ratio to receive either UC-MSCs (40 million cells per infusion) or placebo on days 0, 3, and 6. Main outcome measures The primary endpoints were safety and an altered proportion of whole lung lesion size from baseline to day 28, measured by chest computed tomography. Secondary outcomes were reduction of consolidation lesion sizeand lung function improvement (6-minute walk test, maximum vital capacity, diffusing capacity). Primary analysis was done in the modified intention-to-treat (mITT) population and safety analysis was done in all patients who started their assigned treatment. Results 100 patients were finally recruited to receive either UC-MSCs (n = 65) or placebo (n = 35). The patients receiving UC-MSCs exhibited a trend of numerical improvement in whole lung lesion size from baseline to day 28 compared with the placebo cases (the median difference was -13.31%, 95%CI -29.14%, 2.13%, P=0.080). UC-MSCs administration significantly reduced the proportions of consolidation lesion size from baseline to day 28 compared with the placebo (median difference: -15.45%, 95% CI -30.82%, -0.39%, P=0.043). The 6-minute walk test showed an increased distance in patients treated with UC-MSCs (difference: 27.00 m, 95% CI 0.00, 57.00, P=0.057). The incidence of adverse events was similar, and no serious adverse events were observed in the two groups. Conclusions UC-MSCs treatment is a safe and potentially effective therapeutic approach for COVID-19 patients with lung damage. A phase 3 trial is required to evaluate effects on reducing mortality and preventing long-term pulmonary disability.