MHC Expression in Human Embryonic Stem Cells and Embryoid Bodies / 대한이식학회지

PURPOSE: Human embryonic stem (ES) cell is pluripotent cell derived from a group of cells called the inner cell mass and has the ability to reproduce itself for long periods and give rise to types of cells that develop from the three germ layers. Due to its pluripotency, ES cell holds the promise of being able to replace cells that are damaged or destroyed by many devastating diseases. However, the potential for the recipient of an ES cell transplant to reject this cell as foreign is very high. Thus, it is essential to determine whether human ES cells express MHC antigens. The purpose of this study is to characterize the stem cell properties of our cell line (SNUhES1) and the expression profile of MHC antigens on the surface of these cells and their differentiated derivatives, embryoid bodies (EBs). METHODS: The ES cells were grown on STO fibroblast in DMEM-F12. The EBs were grown in the same medium with exception that it lacked LIF and bFGF. The expression of self-renewal-associated genes and three germ layer cell-specific genes in ES cells and EBs were measured by RT-PCR at varying time point of incubation (1, 7, 14 and 28 day). The expression of MHC molecules were measured by RT-PCR and FACS analysis. RESULTS: The SNUhES1 cells expressed all self-renewal- associated genes (Fgf4, FoxD3, Oct4, Sox2 and TERT) we tested. During the differentiation three germ layer cell-specific genes in EBs were expressed as following order: ecto-, meso- and endodermal cell-specific genes. MHC class I proteins (HLA-ABC and beta2m) on the surfaces of ES cells and EBs were expressed in very low levels. MHC class II proteins (HLA-DP, -DQ and -DR) and HLA-G were not expressed on the surface of these cells. However, the expression of MHC class II proteins were detected in 1% more or less cells of 28-day-old EBs which were hardly detected in the population of 1-day-old EBs. CONCLUSION: These data imply that SNUhES1 cells and EBs have stem cell properties. Although they express very low MHC antigens, further investigation determining whether the MHC expression in the ES cells and EBs may alter under inflammatory condition which can be occurred in damaged tissue or through surgical process.

MHC Antigen Expressions in Human Embryonic Neural Stem Cells and Adult Breast Epithelial Stem Cells / 대한이식학회지

PURPOSE: Due to their unique capacity to self-renew and for multiple differentiation, stem cells are considered potent candidates for cell replacement therapy in many devastating diseases. However, studies on immune rejection, which is a major problem facing successful stem cell therapy, are rare. Thus, we examined MHC expression of human stem cells and effects of IFN-gamma on the MHC class I expression of the cells in order to determine whether human stem cells might be rejected after transplantation. METHODS: The MHC antigen expressions of human embryonic neural stem cell line (HB1.F3) and human breast epithelial stem cell line (M13SV1) were examined by RT-PCR and FACS. The effects of varying concentrations of IFN-gamma and of varying incubation times with IFN-gamma on the expression of MHC class I antigens in these stem cell lines were also examined by FACS. RESULTS: The results show low expression levels of MHC class I antigens on surfaces of these cells. A dramatic induction of MHC class I expression was observed when the cells were treated with IFN-gamma. Maximal induction of MHC class I antigen expression in HB1.F3 and M13SV1 cells was observed at above the concentrations of 20 ng/mL and 5 ng/mL of IFN-gamma 48 h after treatment, respectively. Elevated MHC class I levels in HB1.F3 and M13SV1 cells were sustained for 48 h and 72 h after withdrawing IFN-gamma, respectively. CONCLUSION: These results suggest that human stem cells express high levels of MHC class I antigens, and thus may be rejected on transplantation unless they are modified. Therefore, in addition to studies on stem cell differentiation, studies on overcoming the immunological barriers to stem cell transplantation are prerequisite for successful clinical application of stem cell therapy.

Down-regulation of MHC Expression in Human Stem Cells by Introduction of hCMV US Genes / 대한이식학회지

PURPOSE: Stem cells are considered promising candidates for cell replacement therapy in many devastating diseases. However, it is assumed that stem cells may be rejected on transplantation. Therefore, we introduced human cytomegalovirus (hCMV) US genes, which are known to be able to reduce MHC class I expression on the cell surface after infection, into two known stem cell lines in order to test the feasibility of modifying these cells to reduced MHC class I antigens by the introduction of hCMV US genes. METHODS: The MHC class I expressions of mock-transfected or hCMV US gene-transfected human embryonic neural stem cell line (HB1.F3) and human breast epithelial stem cell line (M13SV1) were examined by FACS. RESULTS: MHC class I expressions in HB1.F3 and M13SV1 cells were dramatically induced by IFN-gamma treatment. In FACS analysis, cells transfected with the hCMV US2, 3, 6 or 11 genes exhibited a dramatic reduction (40~60%) of MHC class I expression compared with mock-transfected cells. CONCLUSION: Our results suggest that human stem cells express high levels of MHC class I antigens, and thus may be rejected on transplantation unless they are odified. In addition introduction of hCMV US genes can be exploited for stemcell transplantation.

Class Ii MHC and Viral Expression by Hematopoietic Progenitor Cells Infected with Friend Virus / 대한면역학회지

No abstract available.