Clinical efficacy and safety of mesenchymal stem cells in viral lung injury treatment

Background High morbidity and mortality have been recorded recently for virus-induced lung injury, which is a serious threat to human health and has become the focus of global attention. Cell-based biotherapy has increasingly garnered attention as a promising avenue for treating such injuries. This study assessed the therapeutic effectiveness of mesenchymal stem cell (MSC) treatment in viral lung injury to provide a scientific foundation for its clinical use. Methods A comprehensive literature search of PubMed, ScienceDirect, Embase, and the Cochrane Library was conducted from inception through to December 2025 to screen eligible randomized controlled trials. The inclusion and exclusion criteria were developed according to PICOS (participants, intervention, comparison, outcomes, study design) principles. The risk of bias was assessed using a literature quality assessment tool. The primary outcome was mortality. Secondary outcomes included adverse events (AEs), serious adverse events (SAEs), hospital stay duration, and inflammatory biomarkers (CRP, IL-6, and IL-8). Results This study included a total of 24 randomized controlled trials. The results of the included studies demonstrated that the MSC-treated patients with viral lung injury had a lower mortality rate than viral lung injury patients who received conventional treatment, (relative risk [RR]: 0.64; 95% confidence interval [95% CI]: 0.53 to 0.77; p < 0.00001). Regarding immune biomarkers, MSC treatment inhibited the patients’ inflammatory response, as indicated by a significant decrease in C-reactive protein (CRP) levels on day 5 (WMD − 18.18, p = 0.03), whereas the reductions on days 3 and 7 were not statistically significant, along with reductions in interleukin (IL)-6 and IL-8 levels. Importantly, AEs incidence (RR: 0.84; 95% CI: 0.74 to 0.95; p = 0.007) and hospital stay duration (WMD: -2.58; 95% CI: -4.54 to -0.63; p = 0.01) were significantly different after MSC treatment, and serious AEs (SAEs) were significantly reduced after MSC treatment (RR: 0.68; 95% CI: 0.48 to 0.97; p = 0.03). Conclusions Mesenchymal stem cells (MSCs) appeared to reduce the inflammatory response, promoted lung tissue repair, and reduced mortality and SAEs in the included studies. MSC treatment of viral lung injury may have therapeutic advantages and warrants further exploration in future clinical applications. Clinical trial number Not applicable.