Single-cell RNA sequencing identifies M2-like macrophage polarization associated with mesenchymal stem cell treatment...

Mesenchymal stem cells (MSCs) have demonstrated therapeutic potential in preclinical models of sepsis, primarily through their immunomodulatory functions. However, the specific mechanistic roles of MSCs in the pathophysiology of sepsis, particularly their interactions with immune cells, are not yet fully understood. In this study, we utilized a murine sepsis model induced by cecal ligation and puncture to assess the effects of adipose-derived MSCs on survival rates, systemic cytokine profiles, and immune cell dynamics. MSCs were administered via tail vein injection immediately after surgery. To investigate cell-specific transcriptional changes and associated pathway enrichment following MSC administration, we performed single-cell RNA sequencing (scRNA-seq) on CD45-positive immune cells isolated six hours postoperatively. Our results indicated that MSC administration significantly improved the survival of septic mice compared to controls. The scRNA-seq analysis revealed dynamic changes in immune cell populations, including increased proportions of both M1 and M2 macrophages. Transcriptomic analysis demonstrated that MSC treatment downregulated inflammatory genes such as Cd14, Cxcl2, Hmgb2, and Pde4b in M0 and M1 macrophages while upregulating regulatory and metabolic genes, including Hmox1, Maf, and Jun. In M2 macrophages, MSCs enhanced the expression of immunomodulatory genes such as Hmox1 and Ccr1, indicating a potential promotion of inflammation resolution. Pseudotime trajectory analysis suggested a transition towards M2-like transcriptional states. Overall, MSC treatment resulted in improved survival in sepsis, characterized by immune modulation, reduced inflammatory signatures, and increased M2-like macrophage profiles. These findings offer mechanistic insights into the therapeutic potential of MSCs and underscore the need for further research to optimize their clinical applications in sepsis.