Transient Fever: The Sole Treatment-Related Adverse Event Associated with Mesenchymal Stromal Cells and Solid Clues from the Real World.

Background: The number of trials investigating mesenchymal stromal cells (MSCs) soars within 3 years which urges a study analysing emerging MSC treatment-related adverse events.

Aim: To assess the safety of MSC therapy and provide solid evidence for clinical translation of MSC.

Methods: A meta-analysis of randomized clinical trials (RCTs) published up to April 20th, 2023 was performed. Odds ratio (OR) and 95% confidential intervals (CIs) were used to display pooled results.

Results: 152 randomized clinical trials (RCTs) that incorporated 9228 individuals treated with MSCs from autologous or allogenic adipose tissue, bone marrow, Wharton's Jelly, and placenta tissue were included in the analysis. We discovered appropriate 21 MSC treatment-related adverse events (TRAEs), of which fever [OR, 1.61, 95% CI: 1.22-2.11, p<0.01] was the sole event that was closely associated with MSC therapy. MSCs also trended to lower the incidence rate of tachycardia [OR, 0.83, 95% CI: 0.64-1.09, p=0.14] and fatigue [OR, 0.18, 95% CI: 0.61-1.07, p=0.18]. A separate analysis of studies with long-term follow-up (more than 1 year) demonstrated the close relationship between MSCs and fever [OR, 1.75, 95% CI: 1.26-2.24, p<0.01]. The rest TRAEs did not associate themselves with MSC therapy. Dose-response was also conducted for fever, linearity was discovered between MSCs from allogeneic tissue and Wharton's Jelly and fever.

Conclusion: To date, our results suggest that fever is the only AE closely associated with MSCs.