Immunomodulatory function of licensed human bone marrow mesenchymal stromal cell-derived apoptotic bodies

Background: Mesenchymal stromal cells (MSCs) show great potential for immunomodulatory and antiinflammatory treatments. Clinical trials have been performed for the treatment of Type 1 diabetes, graft-versus-host disease and organ transplantation, which offer a promise of MSCs as an immunomodulatory therapy. Nevertheless, their unstable efficacy and immunogenicity concerns present challenges to clinical translation. It has emerged that the MSC-derived secretome, which includes secreted proteins, exosomes, apoptotic bodies (ABs) and other macromolecules, may have similar therapeutic effects to parent MSCs. Among all of the components of the MSC-derived secretome, most interest thus far has been garnered by exosomes for their therapeutic potential. However, since MSCs were reported to undergo apoptosis after in vivo transplantation and release ABs, we speculated as to whether ABs have immunomodulatory effects. In this study, cytokine licensing was used to enhance the immunomodulatory potency of MSCs and ABs derived from licensed MSCs in vitro were isolated to explore their immunomodulatory effects as an effective non-viable cell therapy.Results: IFN-gamma and IFN-gamma/TGF-beta 1 licensing enhanced the immunomodulatory effect of MSCs on T cell proliferation. Further, TGF-beta 1 and IFN-gamma licensing strengthened the immunomodulatory effect of MSC on reducing the TNF-alpha and IL-1 beta expression by M1 macrophage-like THP-1 cells. Additionally, we discovered the immunomodulatory effect mediated by MSC-derived apoptotic bodies. Licensing impacted the uptake of ABs by recipient immune cells and importantly altered their phenotypes.Conclusion: ABs derived from IFN-gamma/TGF-beta 1-licensed apoptotic MSCs significantly inhibited T cell proliferation, induced more regulatory T cells, and maintained immunomodulatory T cells but reduced pro-inflammatory T cells.

Automated summary

The study found that IFN-gamma and IFN-gamma/TGF-beta 1-licensed MSCs exhibited enhanced immunomodulatory effects on T cell proliferation, while TGF-beta 1 and IFN-gamma licensing strengthened the immunomodulatory effects of MSCs on reducing TNF-alpha and IL-1 beta expression in M1 macrophage-like THP-1 cells. Additionally, the study discovered an immunomodulatory effect mediated by MSC-derived apoptotic bodies (ABs).