Molecular and cellular regulators of embryo implantation and their application in improving the implantation potential of IVF-derived blastocysts.

Background: In vitro fertilization (IVF) and embryo transfer (ET) are widely used in reproductive biology. Despite the transfer of high-quality blastocysts, the implantation rate of IVF-derived blastocysts remains low after ET.

Methods: This article provides a comprehensive review of current research on embryo implantation regulators and their application to improve the implantation potential of IVF-derived blastocysts.

Main findings: The in vivo mouse model revealed selective proteolysis immediately after expression in activated blastocysts, that is, degradation of ERα expression in activated blastocysts regulated by the ubiquitin-proteasome pathway, followed by completion of blastocyst implantation. Treatment of blastocysts to induce appropriate protein expression during in vitro culture prior to ET is a useful approach for improving implantation rates. This approach showed that combined treatment with PRL, EGF, and 4-OH-E₂ (PEC) improved the blastocyst implantation rates. Furthermore, arginine and leucine drive reactive oxygen species (ROS)-mediated integrin α5β1 expression and promote blastocyst implantation.

Conclusion: Findings based on analysis of molecular and cellular regulators are useful for improving the implantation potential of IVF-derived blastocysts. These approaches may help to elucidate the mechanisms underlying the completion of the blastocyst implantation, although further investigation is required to improve the success of implantation and pregnancy.