Trained human bone marrow mesenchymal stem cells restore tissue immuno-microenvironment in fulminant hepatic failure mice.

Background: Trained immunity with human bone marrow mesenchymal stem cells (hBMSC) is a promising approach to liver regeneration. This study aimed to clarify the trained-hBMSC (T-hBMSC) in restoring tissue immuno-microenvironment in fulminant hepatic failure (FHF) mice.

Methods: hBMSC trained with tumor necrosis factor-α and interferon-γ were phenotypically characterized in vitro. FHF mouse models were established in male Balb/c mice via tail vein injection of concanavalin A. The therapeutic potential of T-hBMSC was evaluated through transplantation into FHF mice. Transcriptomic analysis was performed to elucidate the mechanism of liver regeneration post-transplantation of T-hBMSC.

Results: T-hBMSC with the characteristics of trilineage differentiation potential showed that pro-inflammatory (IL1β, IL8, both p < 0.0001) and immunoregulatory genes (PDL1, IDO1, both p < 0.0001) were significantly upregulated compared to untrained-hBMSC (UT-hBMSC). Time-trajectory analysis revealed downregulation of pro-inflammatory genes (IL6, IL8, and IL1α) and upregulation of immunomodulatory genes (IDO1) in T-hBMSC upon mimic-stimulation, characterized by distinct transcriptional programs. The liver function (ALT, AST) and inflammatory cytokines (IL6, MCP1, both p < 0.01) levels were significantly improved in the T-hBMSC-treated mice. The survival status of the T-hBMSC group was superior to the UT-hBMSC group, although there was no statistical significance. Histological analysis confirmed reduced necrosis and fewer infiltrating CD45 immune cells in the T-hBMSC-treated mice. Significant downregulation of immune response (TNF & IL-17 signaling pathways and neutrophil chemotaxis) and upregulation of metabolic pathways were observed in the T-hBMSC group, associated with enhanced liver regeneration. The proportion of anti-inflammatory F4/80CD163 macrophages was increased in the liver of T-hBMSC group.

Conclusion: T-hBMSC exhibited enhanced immunomodulation, effectively rescuing liver failure and reducing inflammation via restoring the immune-microenvironment. These findings highlighted the potential of trained immunity as a novel strategy for the treatment of liver failure.