Effects of laser-assisted hatching and exposure time to vitrification solution on mouse embryo development

Abstract

ObjectiveThis study was conducted to investigate the efficacy of laser-assisted hatching (LAH) and various vitrification times for embryonic development and blastocyst cell numbers.MethodsFirst, 2-cell and 8-cell embryos were collected by flushing out the oviducts. In the control groups, they were vitrified for 8 or 10 minutes without LAH. The LAH groups underwent quarter laser zona thinning-assisted hatching before vitrification (4, 6, and 8 minutes or 4, 7, and 10 minutes, respectively). After incubation, double-immunofluorescence staining was performed.ResultsThe hatched blastocyst rate 72 hours after the 2-cell embryos were thawed was significantly higher in the 2LAH-ES8 group (33.3%) than in the other groups (p<0.05). In the control-8 group (22.1±4.6), the cell number of the inner cell mass was higher than in the LAH groups (p<0.05). The number of trophectoderm cells was higher in the 2LAH-ES6 group (92.8±8.9) than in the others (p<0.05). The hatched blastocyst rate 48 hours after the 8-cell embryos were thawed was higher in the 8LAH-ES4 group (45.5%) than in the other groups, but not significantly. The inner cell mass cell number was highest in the 8LAH-ES7 group (19.5±5.1, p<0.05). The number of trophectoderm cells was higher in the 8LAH-ES10 group (73.2±12.1) than in the other groups, but without statistical significance.ConclusionWhen LAH was performed, 2-cell embryos with large blastomeres had a lower hatched blastocyst rate when the exposure to vitrification solution was shorter. Conversely, 8-cell embryos with small blastomere had a higher hatched blastocyst rate when the exposure to vitrification solution was shorter.

Murine embryos exposed to human endometrial MSCs-derived extracellular vesicles exhibit higher VEGF/PDGF AA release, increased blastomere count and hatching rates

“…Once the oocyte is fertilized, the embryo undergoes symmetric and asymmetric divisions during morula to blastocyst transition. When it reaches the expanded blastocyst stage, it will escape from the zona pellucida (embryo hatching), being this a mandatory step for successful implantation [ 18 , 19 ]. Even when endometrial MSCs exosomes are presumed to vehicle many soluble factors including cytokines and growth factors, the effect that these vesicles may exert as coadjutants during embryo culture still remains unexplored.…”