Comprehensive transcriptomic analysis reveals stress physiology behind differential gene expression in vitrified–warmed and fresh mouse blastocysts

Blastocyst vitrification has improved embryo transfer methods, leading to higher implantation success rates and better pregnancy outcomes in subsequent frozen embryo transfer cycles. In this study, we used mouse blastocysts as a model to simulate the transcriptional changes caused by vitrifying human blastocysts and to further investigate their effects. Utilizing a human vitrification protocol, we implanted both vitrified and fresh embryos into mice and observed a higher implantation success rate for the vitrified embryos. Transcriptomic analysis revealed that vitrified-warmed blastocysts exhibited differential gene expression primarily associated with thermogenesis, chemical carcinogenesis-reactive oxygen species, oxidative phosphorylation, immune response, and MAPK-related signaling pathways. To validate the next-generation sequencing results, we performed reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR), which confirmed increased expression of genes such as Cdk6 and Nfat2, and decreased expression of genes such as Dkk3 and Mapk10. Among these pathways, immune responses and MAPK-related signaling pathways indicate that embryos need to communicate with the external environment, likely through microRNAs. We used gene-microRNA interaction predictions to anticipate potential embryonic microRNA expressions and conducted an analysis of embryonic microRNA expression. Twelve microRNAs exhibited expression patterns consistent with the predicted results, potentially affecting uterine epithelial cell adhesion, trophectoderm development, invasive capacity, or immune responses. Our findings suggest that vitrification induces transcriptomic changes in mouse blastocysts, and even small changes in gene expression can increase implantation success. Overall design: Embryos from B6CBF1 mice were cultured in human tubal fluidfor 3days. Embryo transfer was performed 2.5 days following mating. Six vitrified–warmed blastocysts were transferred to the right uterine horn in the same recipient. The same number of fresh blastocystswere transferred to the left uterine horn of pseudopregnant recipients. The mice were euthanized4days after embryo transfer.