Safety of DW-MSC infusion in patients with low clinical risk COVID-19 infection: a randomized, double-blind, placebo-controlled trial

Background: Due to their immunomodulatory properties, mesenchymal stem cells (MSCs) have been proposed to have therapeutic potential to improve clinical outcomes in COVID-19. However, the safety and efficacy profile of MSC infusion therapy in patients with non-severe COVID-19 infection has not been completely established; there is, in particular, a substantial void in the literature on dose-dependent studies of MSC infusion in patients with low clinical risk COVID-19 infection. Methods: This phase 1 double-blind, placebo-controlled, randomized clinical trial examines the safety, feasibility, and tolerability of 2 doses (high and low) of DW-MSC in patients with low clinical risk COVID-19. A total of 9 patients were enrolled in this study and randomized into low-dose (TL), high-dose (TH), and placebo (C) groups. Subjects in the TL and TH groups received single intravenous infusions of 5.0 x 10(7) cells and 1.0 x 10(8) cells, respectively. The main outcome was the occurrence of treatment-emergent adverse events (TEAE) during the 28-day study period. Vital signs and various inflammatory markers were also monitored weekly during the observation period. Results: There were no apparent differences in clinical characteristics between study groups (TL,TH, and C) at baseline. All patients did not show the progression of severity during the study period. During the course of the study, 6 episodes of TEAE were observed in 5 subjects; however, none of the TEAEs were severe. During the follow-up period, 8 subjects recovered and were discharged from the hospital without complications. A subject exhibited abnormal liver function biomarkers at the end of the study period. Changes in inflammatory markers throughout the clinical course were not vastly different across study groups. Conclusions: Our clinical trial has provided reliable results regarding the safety of MSCs in low clinical risk COVID-19 subjects treated with MSCs. However, further confirmation of the therapeutic efficacy aspects of MSC will require large-scale randomized controlled trials in subjects with varying severity profiles for COVID-19.