Impact of hypoxic condition on developmental characteristics of mouse blastocysts

Background: Atmospheric O2 concentration during in vitro embryo culture due to increasing the free O2 radical’s levels has a destructive effect on blastocyst quality. Furthermore, in vivo oxygen tension in the reproductive tract of mammalian species is approximately 2 - 8%. Therefore, it is not unexpected that in vitro development of embryos is improved under physiologic oxygen tension. Although this is demonstrated by some recent studies, there are no reports of the importance of O2 reduction in the invasion ability of blastocyst during implantation step. Therefore, in this study, effects of hypoxia condition on the expression level of invasion-related (Mmp-9 and Upa) genes in blastocysts were examined.Methods: In this regard, 2-cell embryos from NMRI mice were distributed into hypoxia (5% O2) and atmospheric (20%O2) groups and were cultured into blastocyst stage. Then, the effect of O2 concentration on the genes expression as well as blastocyst formation, hatching and implantation rate were studied.Result: According to our results, blastocyst formation, hatching and implantation rates are improved when the embryos are cultured in hypoxic condition. Furthermore, real-time RT-PCR analysis data showed an increase in the expression level of Mmp-9 in 5% O2 group. However, there was no significant differences in Upa expression between two groups.Conclusion: In conclusion, it seems that hypoxic condition through increased quality and invasion ability of blastocyst could improve the implantation rate and highlight this condition support better embryo development during in vitro culture.

کلیدواژه ها:

Blastocyst ، Embryo ، Hatching ، Implantation ، MMP9 ، Oxygen ، UPA ، Hypoxia