Expression analysis of an α-1, 3-galactosyltransferase, an enzyme that creates xenotransplantation-related α-Gal epitope, in pig preimplantation embryos.

α-1,3-Galactosyltransferase (α-GalT), an enzyme creating Galα1-3Gal (α-Gal) epitope on the cell surface in some mammalian species such as pigs, is known to be a key factor that causes hyperacute rejection upon transplantation from pigs to humans. To establish the RNA interference-based suppression of endogenous α-GalT messenger RNA (mRNA) synthesis in porcine preimplantation embryos, we determined the suitable embryonic stage at which stage such approach is possible by using the semi-quantitative RT-PCR (qRT-PCR) and the cytochemical method using a fluorescence-labeled Bandeiraea simplicifolia Isolectin B(4) (BS-I-B(4) ). Staining with BS-I-B(4) demonstrated that α-Gal epitope expression was first recognized at the 8-cell stage, and increased up to the hatched blastocyst stage. Single embryo-based qRT-PCR also confirmed this pattern. These results indicate that creation of α-Gal epitope is proceeded by de novo synthesis of α-GalT mRNA in porcine preimplantation embryos with peaking at the blastocyst stage.