title: Chromosomal meiotic segregation, embryonic developmental kinetics and DNA (hydroxy)methylation analysis consolidate the safety of human oocyte vitrification.
abstract: Oocyte vitrification has been introduced into clinical settings without extensive pre-clinical safety testing. In this study, we analysed major safety aspects of human oocyte vitrification in a high security closed system: (i) chromosomal meiotic segregation, (ii) embryonic developmental kinetics and (iii) DNA (hydroxy)methylation status. Fresh and vitrified sibling oocytes from young donors after intracytoplasmic sperm injection (ICSI) were compared in three different assays. Firstly, the chromosomal constitution of the fertilized zygotes was deduced from array comparative genomic hybridization results obtained from both polar bodies biopsied at Day 1. Secondly, embryo development up to Day 3 was analysed by time-lapse imaging. Ten specific time points, six morphokinetic time intervals and the average cell number on Day 3 were recorded. Thirdly, global DNA methylation and hydroxymethylation patterns were analysed by immunostaining on Day 3 embryos. The nuclear fluorescence intensity was measured by Volocity imaging software. Comprehensive chromosomal screening of the polar bodies demonstrated that at least half of the zygotes obtained after ICSI of fresh and vitrified oocytes were euploid. Time-lapse analysis showed that there was no significant difference in cleavage timings, the predictive morphokinetic time intervals nor the average cell number between embryos developed from fresh and vitrified oocytes. Finally, global DNA (hydroxy)methylation patterns were not significantly different between Day 3 embryos obtained from fresh and from vitrified oocytes. Our data further consolidate the safety of the oocyte vitrification technique. Nevertheless, additional testing in young and older sub-fertile/infertile patients and sound follow-up studies of children born after oocyte cryopreservation remain mandatory.
authors.affiliation: Reproduction and Genetics, Vrije Universiteit Brussel (VUB), Laarbeeklaan 101, Brussels, Belgium Centre for Reproductive Medicine, UZ Brussel, Laarbeeklaan 101, Brussels, Belgium neelke.demunck@uzbrussel.be.
authors.forename: N
authors.initials: N
authors.lastname: De Munck
authors.affiliation: Reproduction and Genetics, Vrije Universiteit Brussel (VUB), Laarbeeklaan 101, Brussels, Belgium.
authors.forename: L
authors.initials: L
authors.lastname: Petrussa
authors.affiliation: Centre for Reproductive Medicine, UZ Brussel, Laarbeeklaan 101, Brussels, Belgium.
authors.forename: G
authors.initials: G
authors.lastname: Verheyen
authors.affiliation: Centre for Medical Genetics, UZ Brussel, Laarbeeklaan 101, Brussels, Belgium.
authors.forename: C
authors.initials: C
authors.lastname: Staessen
authors.affiliation: Centre for Medical Genetics, UZ Brussel, Laarbeeklaan 101, Brussels, Belgium.
authors.forename: Y
authors.initials: Y
authors.lastname: Vandeskelde
authors.affiliation: Centre for Reproductive Medicine, UZ Brussel, Laarbeeklaan 101, Brussels, Belgium.
authors.forename: J
authors.initials: J
authors.lastname: Sterckx
authors.affiliation: Centre for Reproductive Medicine, UZ Brussel, Laarbeeklaan 101, Brussels, Belgium.
authors.forename: G
authors.initials: G
authors.lastname: Bocken
authors.affiliation: Reproduction and Genetics, Vrije Universiteit Brussel (VUB), Laarbeeklaan 101, Brussels, Belgium.
authors.forename: K
authors.initials: K
authors.lastname: Jacobs
authors.affiliation: Centre for Reproductive Medicine, UZ Brussel, Laarbeeklaan 101, Brussels, Belgium.
authors.forename: D
authors.initials: D
authors.lastname: Stoop
authors.affiliation: Reproduction and Genetics, Vrije Universiteit Brussel (VUB), Laarbeeklaan 101, Brussels, Belgium Centre for Medical Genetics, UZ Brussel, Laarbeeklaan 101, Brussels, Belgium.
authors.forename: M
authors.initials: M
authors.lastname: De Rycke
authors.affiliation: Reproduction and Genetics, Vrije Universiteit Brussel (VUB), Laarbeeklaan 101, Brussels, Belgium Centre for Reproductive Medicine, UZ Brussel, Laarbeeklaan 101, Brussels, Belgium.
authors.forename: H
authors.initials: H
authors.lastname: Van de Velde
mesh_terms: D020090:Chromosome Segregation; D002875:Chromosomes; D019175:DNA Methylation; D046149:Embryo Culture Techniques; D004622:Embryo, Mammalian / Q000166:cytology; D047108:Embryonic Development; D006801:Humans; D007700:Kinetics; D008540:Meiosis; D009865:Oocytes / Q000166:cytology*; D020554:Sperm Injections, Intracytoplasmic; D059008:Time-Lapse Imaging; D014021:Tissue Preservation / Q000379:methods; D058989:Vitrification
keywords: DNA methylation; PB biopsy; morphokinetics; oocyte; vitrification