The Effects of In Vitro Maturation Technique on The Expression of Genes Involved in Embryonic Genome Activation of Human Embryos

In vitro maturation technique (IVM) is shown to have an effect on full maturation of immature oocytes and the subsequent embryo development. Embryonic genome activation (EGA) is considered as a crucial and the first process after fertilization. EGA failure leads to embryo arrest and possible implantation failure. This study aimed to determine the role of IVM in EGA-related genes expression in human embryo originated from immature oocytes and recovered from women receiving gonadotrophin treatment for assisted reproduction.
In this experimental study, germinal vesicle (GV) oocytes were cultured in vitro. After intracytoplasmic sperm injection of the oocytes, fertilization, cleavage and embryo quality score were assessed in vitro and in vivo. After 3-4 days, a single blastomere was biopsied from the embryos and then frozen. Afterwards, the expression of EGA-related genes in embryos was assayed using quantitative reverse transcriptase-polymerase chain reaction (PCR).
The in vitro study showed reduced quality of embryos. No significant difference was found between embryo quality scores for the two groups (P=0.754). The in vitro group exhibited a relatively reduced expression of the EGA- related genes, when compared to the in vivo group (all of them showed P=0.0001).
Although displaying the normal morphology, the IVM process appeared to have a negative influence on developmental gene expression levels of human preimplanted embryos. Based on our results, the embryo normal morphology cannot be considered as an ideal scale for the successful growth of embryo at implantation and downstream processes.