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.
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