Therapeutic potential of mesenchymal stromal cells in COVID-19: a meta-analysis of clinical trials conducted since the pandemic onset

• MSC therapy significantly reduced all-cause mortality in severe/critical COVID-19 patients (OR=0.74, 95% CI 0.55–0.99) with low heterogeneity and no publication bias. • Subgroup analysis showed a survival benefit specifically in severe/critical cases, but not in studies including moderate cases, suggesting severity-dependent efficacy. • MSC therapy was well tolerated with no significant differences in adverse events or serious adverse events compared to control. • Secondary outcomes indicated improvements in clinical recovery, pulmonary function, and cytokine balance, with potential long-term benefits for Long-COVID symptoms.