Effectiveness and safety of normoxic allogenic umbilical cord mesenchymal stem cells administered as adjunctive treatment in patients with severe COVID-19

Inflammatory response in COVID-19 contributes greatly to disease severity. Mesenchymal Stem Cells (MSCs) have the potential to alleviate inflammation and reduce mortality and length of stay in COVID-19 patients. We investigated the safety and effectiveness of normoxic-allogenic umbilical cord (NA-UC)-MSCs as an adjunctive treatment in severe COVID-19 patients. A double-blind, multicentric, randomized, placebo-controlled trial involving severe COVID-19 patients was performed from January to June 2021 in three major hospitals across Java, Indonesia. Eligible participants (n = 42) were randomly assigned to two groups (1:1), namely the intervention (n = 21) and control (n = 21) groups. UC-MSCs dose was 1 × 10 6 /kg body weight on day D0, D3, and D6. The primary outcome was the duration of hospitalization. Meanwhile, the secondary outcomes were radiographical progression (Brixia score), respiratory and oxygenation parameters, and inflammatory markers, in addition to the safety profile of NA-UC-MSCs. NA-UC-MSCs administration did not affect the length of hospital stay of severe COVID-19 patients, nor did it improve the Brixia score or mMRC dyspnoea scale better than placebo. Nevertheless, NA-UC-MSCs led to a better recuperation in oxygenation index (120.80 ± 72.70 baseline vs. 309.63 ± 319.30 D + 22, p = 0.038) and oxygen saturation (97.24 ± 4.10% vs. 96.19 ± 3.75% in placebo, p = 0.028). Additionally, compared to the placebo group, the treatment group had a significantly smaller increase in PCT level at D + 22 (1.43 vs. 12.76, p = 0.011). No adverse effects, including serious ones, were recorded until D + 91. NA-UC-MSCs therapy is a very safe adjunct for COVID-19 patients. It improves the oxygenation profile and carries potential to suppress inflammation.