title: Vitrification of in vitro matured oocytes diminishes embryo development potential before but not after embryo genomic activation.
abstract: OBJECTIVE
  The aim of this study is to evaluate the impact of oocyte vitrification on embryo development potential and to assess the chromosome abnormalities of blastocysts derived from fresh/vitrified-warmed oocytes to assure the safety of the oocyte cryopreservation technique.
  
  
  METHODS
  In vitro matured oocytes derived from immature oocytes were retrieved from small follicles during IVF/intracytoplasmic sperm injection (ICSI) cycles were randomly divided into a fresh and vitrified-warmed groups. After intracytoplasmic sperm injection, the fertilization rate, embryo quality, and developmental status were compared between the two groups. Blastocysts derived from both groups were analyzed using the copy number variation (CNV)-seq technique to evaluate DNA abnormalities.
  
  
  RESULTS
  The fertilization rate with ICSI and the cleavage rate were similar between the two groups. Among the vitrified-warmed group, there was a lower incidence of usable embryos on day 3 (16.42 vs. 28.57 %; P < 0.05) and a lower incidence of blastocysts (7.46 vs. 17.86 %; P < 0.05). However, the proportions of embryos that developed to blastocysts from the day 3 available embryos were similar between the two groups (62.5 vs. 45.45 %; P > 0.05). In the day 3 embryos, the proportion of >5 cell embryos in the fresh group was markedly higher than in the vitrified-warmed group (41.67 vs. 21.64 %; P < 0.05), and the proportion of embryos with ≧50 % fragments was not significantly different between the two groups (39.29 vs. 43.28 %; P > 0.05). The result of CNV-seq demonstrated that there was no difference in chromosomal abnormalities between the two groups (20 vs. 20 %).
  
  
  CONCLUSIONS
  Oocyte vitrification and the warming procedure diminished the embryo development potential before day 3, when embryo genomic activation started. The day 3 usable embryos derived from vitrified-warmed oocytes had the same potential for developing into blastocysts. Vitrification and the warming procedure did not increase the chromosome abnormalities of the blastocysts. Oocyte vitrification is a safe technique for those patients who have no other options, although the oocyte efficiency may be diminished after the vitrified-warmed procedure.
authors.affiliation: Reproductive Medical Center, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.|Shanghai Ji Ai Genetics & IVF Institute, Obstetrics & Gynecology Hospital, Fudan University, Shanghai, China.
authors.forename: Yijuan
authors.initials: Y
authors.lastname: Sun
authors.affiliation: Shanghai Ji Ai Genetics & IVF Institute, Obstetrics & Gynecology Hospital, Fudan University, Shanghai, China.
authors.forename: Ruihuan
authors.initials: R
authors.lastname: Gu
authors.affiliation: Reproductive Medical Center, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Lu
authors.affiliation: Reproductive Medical Center, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
authors.forename: Shen
authors.initials: S
authors.lastname: Zhao
authors.affiliation: Reproductive Medical Center, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China. Yunfeng_artruijin@163.com.
authors.forename: Yun
authors.identifier: http://orcid.org/0000-0001-7524-3718
authors.initials: Y
authors.lastname: Feng
mesh_terms: D000328:Adult; D001755:Blastocyst / Q000378:metabolism; D002869:Chromosome Aberrations; D056915:DNA Copy Number Variations / Q000235:genetics*; D004624:Embryo Transfer; D047108:Embryonic Development / Q000235:genetics*; D005260:Female; D005307:Fertilization in Vitro; D006801:Humans; D059471:In Vitro Oocyte Maturation Techniques; D008297:Male; D009865:Oocytes / Q000254:growth & development / Q000378:metabolism; D011247:Pregnancy; D018873:Pregnancy Rate; D020554:Sperm Injections, Intracytoplasmic; D058989:Vitrification
keywords: Blastocyst; CNV-seq; ICSI; Oocyte vitrification