In vitro and in vivo viability of human blastocysts collapsed by laser pulse or osmotic shock prior to vitrification

Abstract

Purpose: This study was designed to investigate whether artificial shrinkage, induced by a laser pulse or hyperosmotic sucrose solutions, improves in vitro survival and/or implantation of vitrified-warmed human expanded blastocysts.

Methods: Before Cryotop vitrification, the blastocoelic cavity was collapsed either by a laser pulse or sucrose solutions. Non-treated blastocysts were used as control. Post-warm blastocyst survival and implantation after transfer were examined. Implantation rate outcome was retrospectively analyzed by morphological grading and developmental kinetics of post-warm blastocysts.

Results: Survival rates in the three groups were high. Implantation rates in the laser-pulse group (59.7%) were comparable with those in the sucrose group (49.3%), and were significantly higher than those in the control group (34.2%). The proportion of blastocysts showing fast development tended to be higher when the blastocysts underwent artificial shrinkage treatment before vitrification. There was no clear correlation between morphology of post-warm blastocysts and implantation rate.

Conclusion: Artificial shrinkage treatment before vitrification is associated with an increased probability of fast-developing embryos, resulting in higher implantation rates.

Fig. 1

Artificial shrinkage of blastocoelic cavity in human expanded blastocysts. a Treatment by a laser pulse or b treatment with hyperosmotic sucrose solutions (1) before and (2) after the treatment. Scale bar = 50 μm

Fig. 2

Effect of artificial shrinkage treatments prior to vitrification of human blastocysts on in vitro survival and implantation rates after blastocysts transfer. a-b Different letters on the columns indicate significant difference (P < 0.017: Bonferroni correction)