Immunomodulatory Potential of Human Mesenchymal Stem Cells and their Exosomes on Multiple Sclerosis

Promising advances have been made in mesenchymal stem cell transplantation to reinducethe immune tolerance in neuroinflammatory animal models and multiple sclerosis (MS)patients. The available evidence demonstrated that immunomodulatory effects of mesenchymalstem cell are particularly exerted through releasing exosomes to their environment. Wetherefore, aimed to comparatively assess the potential effect of mesenchymal stem cells andmesenchymal stem cells-derived exosomes on proliferation and function of the CD4⁺CD25^- conventional T cells, isolated from relapsing-remitting MS patients. Mesenchymal stem cells were isolated from human umbilical cord tissues and usedfor exosome isolation via ultracentrifugation. Both mesenchymal stem cells and mesenchymalstem cells-derived exosomes were evaluated for their anti-inflammatory effects againstthe proliferation of T cells isolated from two groups of individuals in vitro, MS patients andhealthy subjects. Cytokine production of conventional T cells (interferon-γ, interleukin-10, andinterleukin-17) was also assessed, using flow cytometry for the patients and healthy individuals. Here, evidence shows that MSCs and MSC-derived exosomes dampen proliferationand percentage of conventional T cells that produce IFN-γ (healthy control: P < 0.001) andinterleukin-17 (healthy control: P <0.001, MS patients: P < 0.001), with a significant increaseof IL-10 producing cells in the patients and healthy individuals. Surprisingly, MSC-derivedexosomes demonstrated higher immune-modulating properties on conventional T cellsresponses, compared to mesenchymal stem cells (MSCs). The current study, provides a novel approach of exocytosis on autoimmune therapy.In particular, Mesenchymal stem cell -derived exosomes, which are cell-derived biologics,could be considered as an alternative for Mesenchymal stem cells in treating MS.