Inhibition of Galectin-3 Expression Could Preserve the Immunoregulatory Function of Mesenchymal Stem Cells During Cell Passaging.

Background: Mesenchymal stem cells (MSCs) are one of the effective treatments for acute graft-versus-host disease (aGVHD) following allogeneic hematopoietic stem cell transplantation (allo-HSCT) due to their potent immunoregulatory function. Given the limited quantity and high heterogeneity of freshly isolated MSCs, extensive in vitro expansion is essential for clinical application. Prolonged passaging of MSCs leads to a decline in therapeutic efficacy, with the underlying mechanisms remaining unclear. This study aimed to explore the mechanism and intervention strategies of immunoregulatory dysfunction of MSCs during passaging.

Methods: We compared the therapeutic effects of MSCs at early passages (passage 6, P6-MSCs) and later passages (passage 12, P12-MSCs) in a mouse GVHD model. We also analyzed the expression of Gal-3 in MSCs at different passages and its role in macrophage polarization. Additionally, the selective Gal-3 inhibitor TD139 was evaluated for its effects on Gal-3 expression and the immunoregulatory function of MSCs.

Results: Our data showed an inverse correlation between passage number and therapeutic efficacy in MSCs. Late-passage MSCs (P12) exhibited significantly reduced efficacy in alleviating GVHD compared to early-passage MSCs (P6). The expression of Gal-3 was markedly upregulated in late-passage MSCs (P12), and it was found to directly inhibit anti-inflammatory M2-like macrophage polarization. Our research demonstrated that TD139 dose-dependently suppresses Gal-3 expression in MSCs and restores their immunoregulatory function.

Conclusion: Gal-3 contributes to the decline in the immunomodulatory capabilities of MSCs. TD139, a Gal-3 inhibitor, has a potentially positive effect on rescuing the immunoregulation dysfunction of MSCs in late-passage and may represent a novel strategy to enhance the therapeutic potential of late-passage MSCs for GVHD treatment.