title: Developmental assessment of human vitrified-warmed blastocysts based on oxygen consumption.
abstract: BACKGROUND
  In this study, we aimed to develop a model for embryo selection based on oxygen consumption following cryopreservation, the relationship between the developmental competence of blastocysts and their oxygen consumption was assessed.
  
  
  METHODS
  Oxygen consumption of vitrified-warmed human blastocysts was measured at 0, 1.5, 3, 4.5, 6, 7.5, 9 and 24 h after warming using scanning electrochemical microscopy. On the basis of their developmental stage at 24 h, blastocysts were classified into four groups (hatched, hatching, arrested and degenerated). Moreover, cytochrome c oxidase (CCO) activity in vitrified-warmed blastocysts was assessed at 0 and 24 h.
  
  
  RESULTS
  The oxygen consumption rate of blastocysts just after warming was significantly lower than that of non-vitrified blastocysts (P< 0.05). The oxygen consumption rate of blastocysts was significantly higher in the hatched group than in the arrested and the degenerated groups after 1.5 h (P< 0.05) and than in the hatching group (P< 0.05) at 7.5 and 9 h. Moreover, CCO activity was absent in vitrified-warmed blastocysts at 0 h, but was detected at 24 h.
  
  
  CONCLUSIONS
  The respiratory rate of vitrified blastocysts after warming was significantly lower than non-cryopreserved blastocysts. Oxygen consumption of blastocysts with high developmental potential was restored earlier than that of blastocysts with low developmental potential. The results of this study suggest that it is possible to select vitrified-warmed blastocysts with high developmental potential based on their respiratory activity.
authors.affiliation: IVF Namba Clinic, Osaka,  Japan.
authors.forename: Masaya
authors.initials: M
authors.lastname: Yamanaka
authors.forename: Shu
authors.initials: S
authors.lastname: Hashimoto
authors.forename: Ami
authors.initials: A
authors.lastname: Amo
authors.forename: Takahiro
authors.initials: T
authors.lastname: Ito-Sasaki
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Abe
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Morimoto
mesh_terms: D001755:Blastocyst / Q000378:metabolism*; D015925:Cryopreservation; D003576:Electron Transport Complex IV / Q000378:metabolism; D046149:Embryo Culture Techniques; D047108:Embryonic Development; D006801:Humans; D008928:Mitochondria / Q000378:metabolism / Q000648:ultrastructure; D010101:Oxygen Consumption
chemical_list: D003576:Electron Transport Complex IV