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Table 2 Impact of oocyte vitrification on DNA methylation and histone modifications in animals

From: What impact does oocyte vitrification have on epigenetics and gene expression?

References Animal model Materials Number of oocytes Number of embryos Technology of assessment Studied sequences Conclusions
Chen et al. [112] Bovine Fresh MII, vitrified MII or embryos (D2-D8) from fresh or vitrified MII after IVM 10–15 oocytes or embryos per group   Immunofluorescence 5mC, H3K9ac, H3K9me3 Decrease in the global DNA methylation and H3K9me3 levels and increase in H3K9ac for vitrified MII oocytes. No difference observed specifically in the ICM. Decrease in the level of DNA methylation and H3K9ac in trophectoderm after oocyte vitrification.
Cheng et al. [113] Murine Blastocysts (D4) from fresh or vitrified MII   30–45 blastocysts per condition Bisulfite treatment + sequencing H19, Peg3, Snrpn No significant differences in oocytes. Decrease in DNA methylation levels for H19, Peg3, and Snrpn in blastocysts after oocyte vitrification.
Zhao et al. [114] Murine Fresh MII, vitrified MII 100 oocytes per group   Bisulfite treatment + sequencing Dnmt1o, Hat1, promoteur de Hdac1 No significant differences.
Hu et al. [115] Bovine Fresh MII after IVM, vitrified MII after IVM 150 oocytes per group   Immunofluorescence Global analysis Decrease in methylation levels after oocytes slow freezing or after use of DMSO.
Increase in methylation levels after using PROH.
Spinaci et al. [116] Porcine Fresh MII after IVM, vitrified MII after IVM H4K5ac 282 fresh oocytes, 192 vitrified oocytes; H3K9me 98 fresh oocytes, 121 vitrified oocytes   Immunofluorescence H3K9 methylation and H4K5 acetylation Increase in H4ac level and significant modifications of H3K9me2 levels (decrease or increase) after oocyte vitrification.
Milroy et al. [117] Murine Fresh MII, fresh MII after IVM, MII after IVM from vitrified GV 200 oocytes per group   Bisulfite treatment + sequencing Pluripotency promotors Oct4, Nanog, Foxd3, Sox2 Increase in the methylation levels of Oct4 (25%) and Sox2 (4.5%) promoters after vitrification of in vitro matured oocytes compared to in vivo matured and fresh MII.
Yan et al. [118] Murine Fresh MII, vitrified MII 66 fresh, 70 vitrified   Immunofluorescence H3K9me, H4K5ac Increase in the H3K9me and H4K5ac levels after oocyte vitrification.
Suo et al. [119] Murine Fresh MII, vitrified MII At least 78 oocytes per group   Immunofluorescence H4K12ac Increase in the H4K12ac levels after oocyte vitrification.
Zygotes from vitrified MII have disturbed levels before and after appearance of pronuclei.
  1. D day of embryo culture, GV oocyte at germinal vesicle stage, ICM inner cell mass, IVM in vitro maturation, 5mC 5-methylCytosine, MII oocyte at metaphase II stage