Changes in DNA methylation and imprinting disorders in E9.5 mouse fetuses and placentas derived from vitrified 8-cell embryos.

Vitrification is increasingly used in assisted reproductive technology (ART) laboratories worldwide, and potential vitrification-induced risks require further exploration. The effect of vitrification on changes in DNA methylation and imprinting disorders was investigated in E9.5 mouse fetuses and placentas. Fetus and placental tissues were collected from the natural mating (NC) group, in vitro culture (IVC) group and vitrified embryo transfer (VET) group. The fetal crown-rump length at E9.5 in both the IVC (0.210 ± 0.059 mm) and VET (0.205 ± 0.048 mm) groups was significantly reduced compared with NC group (0.288 ± 0.083 mm). The global methylation levels of fetuses were decreased in IVC group compared to NC group. And it was increased after vitrification compared to in vitro culture (P<0.05), similar to what was observed in the NC group (P>0.05).The changes could be attributed to disorders of DNMTs and TETs. In the IVC and VET fetuses, a majority of maternally expressed genes were upregulated, which repressed fetal growth. Furthermore, vitrification led to a change in the methylation level of KvDMR1, which resulted in the disturbance of gene imprinting. According to our results, vitrification could contribute to increased methylation compared to in vitro culture and contributes to a gene imprinting disorder rather than recovery. Despite the routine use of embryo vitrification in clinical settings, the effect that this procedure may have on genomic imprinting deserves much greater attention. This article is protected by copyright. All rights reserved.