| Background:Mesenchymal stem cells (MSC), isolated from many tissues, are multipotent stem cells with the capacity for self-renewal and multilineage differentiation. They can be easily isolated and expanded in large quantities. They as important microenvironmental cells support hematopoiesis. Their low immunogenicity and immunoregulation properties make them promising stem cell candidate for tissue engineering and regenerative medicine. Increasing evidence confirms that MSC derived from human fetal umbilical cord matrix (hUC-MSC) have the incomparable advantages:(1) Take full advantage of discarded materials from the new born baby, which are easily accessible and less troublesome in ethical controversy.(2) hUC-MSC are readily long-time preparation and can be scaled up in large numbers because of short doubling time.(3) hUC-MSC contain both human embryonic stem cells and human mesenchymal stem cells markers.(4) hUC-MSC maintain "sternness" for several serial passages. Above all, hUC-MSC offer tremendous promise in cellular therapeutics, while the key to the success is the immunological properties of hUC-MSC. hUC-MSC can suppress T lymphocyte、B lymphocyte and dendritic cell proliferatation and the production of inflammatory cytokines, also successfully treat ongoing graft versus host disease (GVHD). Nowadays, it is indefinite about the immunomodulatory mechanism of hUC-MSC. The studies indicated that mesenchymal stem cells do not have intense ability of immunological suppression unless they are activated by the activated lymphocyte or their products, inflammatory factors. Interferon y, an important kind of proinflammatory cytokine, is secreted by activated T lymphocyte and NK cell. It is used for resisting the virus infection, treating tumors and regulating immune response, etc. So, it is important for us to understand the influence of Interferon y on hUC-MSC. The aim of this study was to investigate the effects of interferon y on biological properties of hUC-MSC.This will provide theoretic foundation and experimental evidence for hUC-MSC used to treat diseases associated with Immune system or hUC-MSC combining with interferon y utilized therapeutically.Objective: The aim of this study was to investigate the effects of interferon y on biological properties of hUC-MSC. This will provide theoretic foundation and experimental evidence for hUC-MSC used to treat diseases associated with immune system or hUC-MSC combining with interferon y utilized therapeutically.Methods:(1) To compare hUC-MSC after IFN-y stimulating phenotypic markers with hUC-MSC without IFN-y stimulating, specific cell-surface and intracellular marker were examined by flow cytometry.(2) hUC-MSC were induced for adipocytes and osteoblasts in the specific-induction medium. Oil red O staining and Von Kossa staining were performed to examine lipid droplet and mineralization.(3) The proliferations tatus of hUC-MSC with IFN-y stimulating or not was detected by CCK-8assay.(4) hUC-MSC and human peripheral blood mononuclear cells (hPBMC) were cocultured in vitro. hPBMC proliferation was assessed by Brdu ELISA kits (Brdu incorporation assay).(5) PGE-2secretion by hUC-MSC with IFN-y stimulating or not was detected by ELISA kits.(6) The hUC-MSC mRNA expression level of COX-2, IDO-1and IDO-2, IFN-y pretreatment or not, were detected by real-time quantitative PCR.Result:(1) hUC-MSC expressed the embryonic stem cell specific markers. After IFN-γ stimulation, the expression of SSEA-4on hUC-MSC decreased significantly (8.15+2.94%vs16.42+8.5%, p<0.05), and the expression of CD54increased (96.64±3.29%vs84.12+10.73%, p=0.051).(2) hUC-MSC effectively differentiate toward adipogenic and osteogenic in lineage-specific inductive condition, indicating that hUC-MSC possess multilineage differentiation potential. After IFN-y stimulation, the lipid droplet formation ability of hUC-MSC had abated when hUC-MSC was induced for adipocytes, but mineralization did not have much difference between the two groups under the microscope.(3) The multiplication capacity of hUC-MSC did not have statistic difference between the two groups.(4) hUC-MSC exhibited inhibition on the cell proliferation of human peripheral blood mononuclear cells (hPBMC) when hUC-MSC and hPBMC were cocultured in vitro. After IFN-γ stimulation, hUC-MSC had stronger inhibition capacity (p<0.05). The influence of IFN-γ on hUC-MSC exhibited a dose-dependent and when the concentration was10ng/ml, IFN-γ could activate the immunologic suppression property of hUC-MSC.(5) After IFN-γ10ng/ml stimulated for48hours, PGE-2production of hUC-MSC increased significantly (p<0.01).(6) After IFN-γ10ng/ml stimulated for24hours, The mRNA expression level of COX-2decreased though the difference did not reach up to statistical significance, the mRNA expression level of IDO-1in IFN-γ group increased significantly (p<0.01), and the mRNA expression level of IDO-2remained unchanged.Conclusion:The study demonstrated that IFN-γ can influence the the expression of SSEA-4and CD54on hUC-MSC and enhance the immunomodulatory activity of hUC-MSC through increasing IDO-1expression. |
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