EXTENDED EXPOSURE TIME TO EMBRYOGLUE™ Results IN IMPROVED MOUSE FETAL DEVELOPMENT

Abstract

Human data point towards positive effects of extended incubation times in EmbryoGlue. In the mouse, Gardner and collaborators demonstrated a beneficial effect on implantation after 5 minutes incubation in medium with high levels of hyaluronan. Clinical practice using EmbryoGlue has confirmed its beneficial effect (Heymann et al., 2020). The aim of this study was to evaluate the effect of extended incubation times of mouse embryos in EmbryoGlue on implantation and fetal development. Mouse embryos from hybrid B6CBAF1 females were cultured from the one-cell stage up to day-4 in G-TL before incubation in the transfer medium (Control: G-TL or Test: EmbryoGlue). Transfer dishes with 0.5 mL of medium under oil were prepared and equilibrated overnight. Day-4 blastocysts were randomly allocated to the control and test group. Embryos were incubated for 10 minutes, 1 hour or 4 hours prior to transfer. Transfer procedures were performed using synchronized CD1 pseudopregnant females. For each transfer, the uterine horns were randomized and 4-5 embryos from the control and test group were replaced in each recipient. In total, 90 to 95 blastocysts were transferred from each group in 18 to 19 embryo transfer procedures. Outcome was assessed 10 days after embryo transfer. Implantation sites and fetal development were determined and crown-rump length, fetal and placental weight measured. Results of implantation, loss rate and fetal development are summarized in the table. No significant differences in implantation rates between the control and the test were observed at the different incubation times. A significantly lower (p<0.05) rate of implantation loss after 4 h exposure to EmbryoGlue resulted in increased fetal development in this group (p<0.05) compared to the corresponding control. No statistical differences were found in the mean values of crown-rump length, fetal and placental weight between the different groups. Compared to a medium with low levels of hyaluronan, exposure of mouse embryos to a medium containing high levels of hyaluronan for 4 h before transfer reduces loss rates after implantation and increases fetal development with no effect on fetal outcome parameters on day 14 of gestation.