Down-regulation of HLA-G attenuates cleavage rate in human triploid embryos

ABSTRACT

HLA-G is a major histocompatibility complex [MHC], class Ib molecule that is selectively expressed at the fetal maternal interface. It is thought to play a role in protecting the fetus from the maternal immune response. Interestingly, the preimplantation embryo development [Ped] gene product Qa-2 is also a mouse MHC class Ib protein that affects cleavage and division of preimplantation mouse embryos and subsequent embryonic survival. Data from many human in vitro fertilization [IVF] clinics suggest that the mouse Ped phenomenon also exists in human because embryos fertilized at the same time have different cleavage rates and consequently different IVF outcomes. As HLA-G is expressed in human early embryos, it is highly regarded as the functional homologue of Qa-2. Whether HLA-G expression is correlated with the cleavage rate of human embryos has great potential clinical value. In this study, 45 human early abnormal fertilized embryos [3 PN] from patients undergoing in vitro fertilization were used to test the effects of HLA-G knock-down via infection with adenovirus carrying its specific siRNA on the cleavage rate in a 2-day culture period. One-way ANOVA, Post hoc and Chi-square were used to compare groups. A p-value smaller than 0.05 was considered statistically significant. Knocking-down HLA-G in human pre-implantation stage embryos resulted in a higher cell arrest rate and a slower cleavage rate. The results from the present study suggested that HLA-G might play an important role in early human embryo development