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

Purpose: Promising advances have been made in mesenchymal stern cell transplantation to reinduce the immune tolerance in neuroinflammatory animal models and multiple sclerosis (MS) patients. The available evidence demonstrated that immunomodulatory effects of mesenchymal stem cell are particularly exerted through releasing exosomes to their environment. We therefore, aimed to comparatively assess the potential effect of mesenchymal stem cells and mesenchymal stem cells-derived exosomes on proliferation and function of the CD4(+)CD25(-) conventional T cells, isolated from relapsing-remitting MS patients. Methods: Mesenchymal stem cells were isolated from human umbilical cord tissues and used for exosome isolation via ultracentrifugation. Both mescnchymal stem cells and mesenchymal stem cells-derived exosomes were evaluated for their anti-inflammatory effects against the proliferation of T cells isolated from two groups of individuals in vitro, MS patients and healthy subjects. Cytokine production of conventional T cells (interferon-gamma, interleukin-10, and interleuldn-17) was also assessed, using flow cytometry for the patients and healthy individuals. Results: Here, evidence shows that MSCs and MSC-derived exosomes dampen proliferation and percentage of conventional T cells that produce IFN-gamma (healthy control: P<0.001) and interleukin-17 (healthy control: P <0.001, MS patients: P <0.001), with a significant increase of IL-10 producing cells in the patients and healthy individuals. Surprisingly, MSC-derived exosomes demonstrated higher immune-modulating properties on conventional T cells responses, compared to mesenchymal stem cells (MSCs). Conclusion: 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.