alternation of apoptotic and implanting genes expression of mouse embryos after re-vitrification

background: nowadays, oocytes and embryos vitrification has become a routine technique. based on clinical judgment, re-vitrification maybe required. but little is known about re-vitrification impact on genes expression. objective: the impact of re-vitrification on apoptotic and implanting genes, bax, bcl-2 and erbb4, at compaction stage embryos were evaluated in this study. materials and methods: in this experimental study, 8 cell embryos (n=240) were collected from female mature mice, 60-62 hr post hcg injection. the embryos were divided randomly to 3 groups included: fresh (n=80), vitrified at 8 cell stage (n=80), vitrified at 8 cell stage thawed and re-vitrified at compaction stage (n=80). embryos were vitrified by using cryolock, (open system) described by kuwayama. q-pcr was used to examine the expression of bax, bcl2 erbb4 genes in derived blastocysts. results: our result showed that expanded blastocyst rate was similar between vitrified and re-vitrified groups, while re-vitrified embryos showed significant decrease in expanded blastocyst rate comparing with fresh embryos (p=0.03). in addition, significant difference was observed on apoptotic gene expression when comparing re-vitrified and fresh embryos (p=0.004), however expression of bax and bcl-2 (apoptotic) genes didn't demonstrate a significant difference between re-vitrified and vitrified groups. the expression rate of erbb4, an implantation gene was decreased in re-vitrified embryos comparing with fresh embryos (p=0.003), but it was similar between re-vitrified and vitrified embryos. conclusion: re-vitrification can alter the expression of bax, bcl-2 and erbb4 genes and developmental rate of mouse embryos in compaction stage.