Regulatory Effect of Exosomes Derived from Human Umbiilcal Cord Mesenchymal Stem Cells on Treg and TH17 Cells

OBJECTIVE: To investigate the effects of exosomes from human umbilical cord mesenchymal stem cells on the development of Treg and TH17 cells. METHODS: Exosomes from the serum-free-culture supernatants of hUC-MSC were harvested by ultracentrifugation. The electron microscopy, nanoparticle tracking analysis and western blot were used to identify the hUC-MSC-exosomes, such as the morphology, the paticle chameter, and the protein content. The PBMC stimulated with anti-CD3/CD28 were incubated with the exosomes for five days, and then the percentage changes of Treg and TH17 cells were analyzed by using flow cytometry. RESULTS: The hUC MSC-derived exosomes were saucer-like in morphology the averge diameter was approximately 142 nm. They were identified as positive for CD9 and CD63. Flow cytometry showed that the proportion of CD4+CD25+Foxp3+ Treg cells in the PBMC were significantly higher, but the proportion of CD4+IL17A+ T cells in the hUC-MSC-exosome group was obviously lower than that in the group without the hUC-MSC-exosom (control group) (P<0.05). CONCLUSION: The hUC-MSC-exosomes have an immunomodulatory effect on T cells in vitro by increasing the ratio of Treg and reducing the ratio of TH17 cells, expecting the hUC-MSC-exosom as a novel cell-free target for immunotherapy.