Exosomes secreted from IFN-γprestimulated hUC-MSCs induce regulatory T cells / 中国药理学通报

ABSTRACT

Aim To investigate whether human umbili-cal cord mesenchymal stem cells(hUC-MSCs)exposed to inflammatory conditions could release large amounts of exosomes to induce regulatory T cells(Treg).Meth-ods hUC-MSCs were isolated by enzyme digestion method.(In vitro)interferonγ(IFN-γ)was added in-to hUC-MSCs to mimic inflammatory microenviron-ments,then exosomes were extracted from the superna-tant of normal conditional medium or IFN-γpretreated hUC-MSCs.Both sources of exosomes,Nor-hUC-exo and IFN-γ-stimulated hUC-exo, were identified by Nanoparticle Trafficking Analysis (NTA )and Western blot for the exosome-enriched protein CD63 .Next,hu-man peripheral blood mononuclear cells (PBMCs ) stimulated with PHA were respectively co-cultured with hUC-MSCs,IFN-γ-pretreated-hUC-MSCs,hUC-MSCs exosomes or IFN-γ-stimulated-hUC-MSCs exosomes for 5 days to assess the exosomes-T cells communication. The proliferation rate of PBMCs and frequency of CD4 +/CD25 +/Foxp3 + Treg were measured by flow cytometry.Results The isolated cells from human um-bilical cord tissue,which were positive for CD73, CD44,CD29,CD90 and HLA-ABC,but were nega-tive for CD31 and CD34,were mesenchymal stem cells indeed.After IFN-γtreatment,hUC-MSCs secreted nu-merous exosomes(P<0.05 ).Morerover,there was a significantly higher level of CD63 ,but no difference in diameter between Nor-hUC-exo and IFN-γ-stimulated hUC-exo.IFN-γ-stimulated hUC-exo had a superior a-bility compared with Nor-hUC-exo to suppress the pro-liferation of PHA stimulated PBMCs due to their upreg-ulation of the percentage of Treg (1 1.53 ±0.88% vs 6.60 ±0.56%,P <0.01 ).Conclusion hUC-MSCs could promote the expression of Treg to modulate im-munosuppression through exosomes,especially for IFN-γ-licenced exosomes,which might carry much immu-notherapeutic potential.