Effect of TGF-β1 and IL-10 on the Immunoregulatory Function of Extracellular Vesicles Derived from Mesenchymal Stem Cells

Abstract

To investigate the effect of immune regulatory molecules TGF-β1 and IL-10 on the immunoregulatory activities of extracellular vesicles(EV) secreted from mesenchymal stem cells (MSCs). MSC were isolated from human umbilical cord and expanded, then were treated with TGF-β1 and IL-10 for 72h, and MSC-EVs in supernatants were isolated. The total protein content of all samples was determined by BCA methed. The morphological structure was observed by transmission electron microscopy. The surface markers of MSC-EV were analyzed by flow cytometry. The apoptosis of peripheral blood mononuclear cells(PBMNC) stimulated by ConA and the proportion of CD4+CD25+/CD127- (Treg) cells were detected by flow cytometry after incubation with MSC-EV for 72 h. The CBA and ELISA kit were used to detect the contents of IL2, IL4, IL6, IL10, IFN-γ, TNF-α, Th17A and TGF-β1 in PBMC supernatants and MSC-EV. All the samples showed that the typical cup-shaped membrane-like structure was observed by transmission electron microscopy, and CD9, CD44, CD63 and CD81 expressed. After TGF-β1 treatment, the MSC-EV displayed the strongest ability to promote PBMNC apoptosis（P<0.01）, and in all the samples the proportion of Treg cells increased. MSC-EV could increase the content of IL-10 in the supernatants of PBMNC culture, the content of TGF-β1 in PBMNC supernatants after MSC treatment with TGF-β1 was lower than that in untreated group(P<0.05). The content of IL-6 in MSC-EV increased significantly after treatment with TGF-β1, and the content of TGF-β1 decreased. TGF-β1 alters the immnomodulatory function of MSC-EV and its underlying mechanisms need to be clarified in further investigations.