Mesenchymal stem cells-derived exosomes improve pregnancy outcome through inducing maternal tolerance to the allogeneic fetus in abortion-prone mating mouse.

Recurrent pregnancy loss (RPL) is three or more times of consecutive spontaneous loss of pregnancy. The underlying cause is complicated and the etiology of over 50% of RPL patients is unclear. In the present study, bone marrow mesenchymal stem cells were isolated from CBA/J female mice and exosomes were isolated from cell culture medium by ultracentrifugation. CBA/J female mice were paired with male DBA/2 to generate abortion prone mouse model, and CBA/J females paired with male BALB/c mice were used as control. Exosomes were injected through uterine horns into pregnant CBA/J mice on day 4.5 of gestation in abortion-prone matting. On day 13.5 of pregnancy, abortion rates were calculated and the level of transforming growth factor-β (TGF-β), interleukin 10 (IL-10), interferon g (IFN-γ), and tumor necrosis factor a (TNF-α) in CD4+ T cells and macrophages in deciduas were evaluated by flow cytometry. Exosomes injection improved the pregnancy outcomes in abortion prone mice. The IL-4 and IL-10 levels on CD4+ T cells were upregulated in the maternal-fetal interface; meanwhile, the TNF-α and IFN-γ levels on CD4+ T cells were reduced. The IL-10 level was increased and IL-12 was reduced on the monocytes that separated from deciduas. miR-101 level was increased in the CD4+ T cells in the deciduas. In conclusion, the treatment of ESCs-derived exosomes modulates T cells' function and macrophages activities in the maternal-fetal interface that resulted in a decreased embryo resorption rate, and provides a therapeutic potential to treat RPL.