In Vitro and In Vivo Immunomodulatory and Protective Effects of Leukemia Inhibitory Factor‐Engineered Mesenchymal Stromal Cells in Experimental Endotoxemia

Sepsis is a life‐threatening condition characterized by dysregulated systemic inflammation and high mortality rates. Mesenchymal stem/stromal cells (MSCs) have emerged as promising immunomodulatory agents; however, genetic engineering strategies can enhance their therapeutic efficacy. This study evaluated the immunomodulatory and protective effects of MSCs genetically engineered to express leukemia inhibitory factor (MSC‐LIF) in vitro and in a mouse model of lipopolysaccharide (LPS)‐induced endotoxemia. In vitro, peritoneal macrophages stimulated with LPS + IFN‐γ were co‐cultured with MSC‐LIF or wild‐type MSCs (MSC‐WT). MSC‐LIF significantly reduced the production of TNF‐α, IL‐12, and nitric oxide compared with stimulated controls and demonstrated enhanced inhibition of IL‐12 and nitrite levels relative to MSC‐WT. Although IL‐6 levels increased in co‐cultures, MSC‐LIF promoted a regulatory cytokine profile characterized by modulation of pro‐inflammatory mediators. In vivo, C57BL/6 mice subjected to lethal endotoxemia with LPS were treated with MSC‐LIF, MSC‐WT, dexamethasone, or vehicle. MSC‐LIF significantly improved survival in a dose‐dependent manner, achieving 100% survival at the highest dose (1 × 10 6 cells), outperforming MSC‐WT. Serum cytokine analysis revealed that MSC‐LIF markedly reduced TNF‐α, IL‐6, IL‐1β, and IL‐12 levels while significantly increasing IL‐10 production, indicating enhanced systemic immunoregulation. Collectively, these findings demonstrate that LIF expression potentiates the immunomodulatory and protective effects of MSCs in experimental endotoxemia. MSC‐LIF therapy promotes a balanced inflammatory response and significantly improves survival, supporting its potential as a novel therapeutic strategy for severe systemic inflammatory conditions such as sepsis.