Developmental Potential of Human Oocytes After Slow Freezing or Vitrification: A Randomized In Vitro Study Based on Parthenogenesis

Abstract

The aim of the this study was to compare the in vitro developmental competence of parthenogenetically activated oocytes cryopreserved with slow-freezing or vitrification. Supernumerary metaphase II oocytes obtained during in vitro fertilization procedures were randomized to slow freezing or vitrification procedure. After thawing or devitrification, oocytes were parthenogenetically activated and cultured. Survival, activation, development rate, and cell number during culture were compared. The 2 groups showed no significant differences between the rates of parthenogenetic activation, development, good quality parthenotes and blastomere number on day 2 of culture. However, parthenotes from the devitrified oocytes continued cleaving till day 3 in a significantly low proportion (27% vs. 42%). On day 3, the mean number of blastomeres was also lower in vitrification group compared to slow-freezing (4.8 + 1.9 vs. 5.8 + 1.7). In conclusion, parthenogenesis highlights a reduced potential of vitrified oocytes to cleave on day 3 compared with oocytes from slow-freezing.

Parthenogenic activation of surplus in vitro–matured human oocytes: a tool for validation of oocyte cryopreservation

“…The activation and cleavage rates demonstrated in this study are comparable to reports using fresh, unfertilized oocytes and indicate that oocytes that are immature at time of ICSI but mature overnight provide a suitable model for validating cryopreservation (14). Our study used in vitro-matured oocytes that were never inseminated.…”

“…Artificial activation of human oocytes to yield parthenotes has been studied extensively (12) and provides a means to measure developmental competence (13). Because parthenogenesis provides an alternative to natural fertilization for the study of developmental competence, it has been used to study oocyte cryopreservation (14,15).…”

Oocyte, embryo and blastocyst cryopreservation in ART: systematic review and meta-analysis comparing slow-freezing versus vitrification to produce evidence for the development of global guidance

“…(2005) Taiwan Randomization of embryos Vitrification 20% EG + 20% DMSO and 0.5 M sucrose – open system Blastocyst vitrification 81 embryos Blastocyst slow-freezing 72 embryos cryosurvial rate Serious risk of bias due to randomization method, concealment of allocation, blinding Human Reproduction: 4.621 Slow-freezing: 5% glycerol + 9% glycerol 0.2 M sucrose Kim et al . (2000) USA Randomization of embryos Vitrification 5.5 M EG + 1 M sucrose Blastocyst vitrification 42 cycles Blastocyst slow-freezing 216 cycles CPR, cryosurvival rate Unclear risk of bias related to random sequence generation, allocation of concealment acceptable, and blinding Fertility and Sterility: 4.426 Slow freezing: 5% glycerol and 9% glycerol + 0.2 M sucrose 141 embryos 790 embryos Paffoni et al . (2008) Italy Randomization of sibling oocytes Vitrification 15% DMSO, 15% EG, and 0.5 M sucrose – closed system Oocyte vitrification 90 oocytes Oocyte slow-freezing 90 oocytes Cryosurvival rate Serious risk of bias due to randomization method, concealment of allocation, blinding Reproductive Sciences: 2.429 Slow freezing: 1.5 mol/L PROH and 0.3 mol/L sucrose …”

The Gametotoxic Effects of the Endometrioma Content: Insights From a Parthenogenetic Human Model

“…Given the difficulties in obtaining clear embryological data in the clinical settings and the debatable reliability of animal models, we designed a randomized, controlled, in vitro study with the objective of evaluating the effect of exposure of human cryopreserved oocytes to endometriotic fluid. To this aim, we used a validated experimental model of human parthenogenesis [21][22][23][24][25][26] .…”