Selection of blastocysts with higher implantation potential based on reactive oxygen species levels before embryo transfer in mice.

OBJECTIVE

To evaluate and select blastocysts with higher implantation potential using reactive oxygen species (ROS) levels and glutathione (GSH) regulated by arginine (Arg) with leucine (Leu).

DESIGN

Experimental study.

SUBJECTS: ICR mice.

EXPOSURE: In vitro fertilization (IVF)-derived blastocysts were treated with Arg and Leu for 24 hours. A microgrid array was used for live-cell imaging of individual blastocysts, followed by embryo transfer to recipient females.

MAIN OUTCOME MEASURES: Both ROS and GSH levels in individual blastocysts, selection of blastocysts at the ROS level, embryo transfer (ET), and implantation rates.

RESULTS

For each in vitro fertilization cycle followed by ET, approximately 20 blastocysts were provided to measure levels of ROS and GSH. The ROS levels in individual blastocysts showed substantial variation, whereas the GSH levels were low and similar in each blastocyst. Therefore, the blastocysts were ranked and divided into two groups based on their ROS levels. The top six blastocysts were classified as the high-ROS group, and the bottom six as the low-ROS group. Blastocysts from the high- and low-ROS groups were transferred to one or the other uterine horns of the same female recipient mice, respectively. The implantation rate was significantly higher in the high-ROS group than in the low-ROS group.

CONCLUSION

This study demonstrates that blastocysts with higher implantation potential can be selected on the basis of their ROS levels before ET. Increased ROS levels caused by the combination of Arg and Leu indicate a higher implantation potential in the blastocysts. This study also proposes a direct selection method for blastocysts using a live-cell imaging assay for ET.