Study of immunomodulatory function of exosomes derived from human umbilical cord mesenchymal stem cells

Objective: To investigate the immumodulation ability of exosomes secreted from human umbilical cord-derived mesenchymal stem cells (hUC-MSCs).

Methods: hUC-MSCs were isolated and cultured.Exosomes were isolated from the culture media of the third-generation hUC-MSCs. The expression of specific surface marker CD9 and CD81 were detected by Western blot, and the concentration of hUC-MSCs exosomes(hUC-MSCs-ex) was evaluated by BCA assay. CD3/CD28-stimulated peripheral blood mononuclear cells(PBMCs) from healthy donor were co-cultured with different concentration of hUC-MSCs-ex for 72 h. The percentage of Th17 and Treg cells and the proliferation of CD4⁺ and CD8⁺ T cells were detected by flow cytometry. ELISA was used to test the level of IFN-γ, IL-6, TNF-α and TGF-β1.

Results: hUC-MSCs-ex inhibited the proliferation of CD4⁺ and CD8⁺ cells obviously,and increased the proportion of CD4⁺ CD25⁺ FoxP3⁺ Treg cells, with high expression of CD81 and CD9. After CD3/CD28 monoclonal antibody stimulated, the percentage of CD45⁺ CD4⁺ Ki67⁺ and CD45⁺ CD8⁺ Ki67⁺ cells were 85.3% ± 5.6% and 72.6% ± 6.3%, respectively. Meanwhile, the level of TGF-β1 were elevated and the level of IFN-γ, IL-6 and TNF-α were decreased (P<0.05).

Conclusions: hUC-MSCs-ex has the immunomodulatory functionin vitro, which could be a new therapeutic agent for the treatment of immune disorders.