title: Comparison of 2, 5, and 20 % O2 on the development of post-thaw human embryos.
abstract: OBJECTIVE
  The objective of this study is to investigate the effect of 2, 5, and 20 % O2 on post-thaw day 3 human embryo culture until blastocyst stage.
  
  
  METHODS
  One hundred fifty-five day 3 human embryos were used. One hundred twenty out of 155 embryos were recovered after thawing. Surviving embryos were distributed into 2, 5, or 20 % O2 groups and cultured for 2.5 days. At the end of culture, blastocyst formation was assessed, and then, embryos were collected for RT-qPCR or immunofluorescence analysis.
  
  
  RESULTS
  Using visible blastocoel to define blastocyst formation, 58.7 % (27/46) of surviving day 3 embryos formed blastocyst at 2 % O2, 63.6 % (28/44) at 5 % O2, and 66.7 % (20/30) at 20 % O2. The difference in blastocyst formation rates was not significant. Average blastocyst cell number was 119.44 ± 11.64 at 2 % O2, 142.55 ± 22.47 at 5 % O2, and 97.29 ± 14.87 at 20 % O2. Average apoptotic rate was 4.7 % ± 0.4 % for blastocyst formed at 2 % O2, 3.5 % ± 0.7 % at 5 % O2, and 5.8 % ± 1.1 % at 20 % O2. Apoptosis rate was significantly lower for blastocysts formed at 5 % O2 (p < 0.05). Compared with gene expression levels at 5 % O2, which were arbitrarily set as "1," 20 % O2 is associated with significantly higher expression of BAX (2.14 ± 0.47), G6PD (2.92 ± 1.06), MnSOD (2.87 ± 0.88), and HSP70.1 (8.68 ± 4.19). For all genes tested, no significant differences were found between 2 and 5 % O2.
  
  
  CONCLUSIONS
  The result suggests that development of cryopreserved human embryos from day 3 to blastocyst stage benefits from culture at 5 % O2.
authors.affiliation: Center for Reproductive Medicine, First Affiliated Hospital of Sun Yat-sen University, Guangzhou, 510080, China.|Ob/Gyn, Wayne State University Medical School, 275 East Hancock Street, Detroit, MI, 48201, USA.|Reproductive Sciences/Physiology, Wayne State University Medical School, 540 East Canfield, Detroit, MI, 48201, USA.
authors.forename: Yu
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Center for Reproductive Medicine, First Affiliated Hospital of Sun Yat-sen University, Guangzhou, 510080, China.|Key Laboratory of Reproductive Medicine of Guangdong Province, Guangzhou, China.
authors.forename: Yanwen
authors.initials: Y
authors.lastname: Xu
authors.affiliation: Center for Reproductive Medicine, First Affiliated Hospital of Sun Yat-sen University, Guangzhou, 510080, China.|Key Laboratory of Reproductive Medicine of Guangdong Province, Guangzhou, China.
authors.forename: Chenhui
authors.initials: C
authors.lastname: Ding
authors.affiliation: Center for Reproductive Medicine, First Affiliated Hospital of Sun Yat-sen University, Guangzhou, 510080, China.|Key Laboratory of Reproductive Medicine of Guangdong Province, Guangzhou, China.
authors.forename: Rabea Youcef
authors.initials: RY
authors.lastname: Khoudja
authors.affiliation: Center for Reproductive Medicine, First Affiliated Hospital of Sun Yat-sen University, Guangzhou, 510080, China.|Key Laboratory of Reproductive Medicine of Guangdong Province, Guangzhou, China.|Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, 100191, China.
authors.forename: Mingmei
authors.initials: M
authors.lastname: Lin
authors.affiliation: Ob/Gyn, Wayne State University Medical School, 275 East Hancock Street, Detroit, MI, 48201, USA.
authors.forename: Awoniyi O
authors.initials: AO
authors.lastname: Awonuga
authors.affiliation: Ob/Gyn, Wayne State University Medical School, 275 East Hancock Street, Detroit, MI, 48201, USA.
authors.forename: Jing
authors.initials: J
authors.lastname: Dai
authors.affiliation: Ob/Gyn, Wayne State University Medical School, 275 East Hancock Street, Detroit, MI, 48201, USA.
authors.forename: Elizabeth E
authors.initials: EE
authors.lastname: Puscheck
authors.affiliation: Ob/Gyn, Wayne State University Medical School, 275 East Hancock Street, Detroit, MI, 48201, USA.|Reproductive Sciences/Physiology, Wayne State University Medical School, 540 East Canfield, Detroit, MI, 48201, USA.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Rappolee
authors.affiliation: Center for Reproductive Medicine, First Affiliated Hospital of Sun Yat-sen University, Guangzhou, 510080, China. zhoucanquan@hotmail.com.|Key Laboratory of Reproductive Medicine of Guangdong Province, Guangzhou, China. zhoucanquan@hotmail.com.
authors.forename: Canquan
authors.initials: C
authors.lastname: Zhou
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D001755:Blastocyst / Q000166:cytology* / Q000187:drug effects; D018031:Connexin 43 / Q000235:genetics; D015925:Cryopreservation; D004268:DNA-Binding Proteins / Q000235:genetics; D046149:Embryo Culture Techniques / Q000379:methods*; D004624:Embryo Transfer / Q000379:methods*; D047108:Embryonic Development / Q000187:drug effects*; D005260:Female; D051272:Glucose Transporter Type 1 / Q000235:genetics; D005954:Glucosephosphate Dehydrogenase / Q000235:genetics; D006801:Humans; D007247:Infertility, Female; D007248:Infertility, Male; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics; D008297:Male; D009687:Nuclear Proteins / Q000235:genetics; D010100:Oxygen / Q000494:pharmacology*; D012333:RNA, Messenger / Q000096:biosynthesis; D013482:Superoxide Dismutase / Q000235:genetics; D051028:bcl-2-Associated X Protein / Q000235:genetics
chemical_list: C490117:AKAP8L protein, human; D018031:Connexin 43; D004268:DNA-Binding Proteins; D051272:Glucose Transporter Type 1; D047908:Intracellular Signaling Peptides and Proteins; D009687:Nuclear Proteins; D012333:RNA, Messenger; C495677:SLC2A1 protein, human; D051028:bcl-2-Associated X Protein; D005954:Glucosephosphate Dehydrogenase; D013482:Superoxide Dismutase; D010100:Oxygen
keywords: Apoptosis; Human embryo; Oxygen; PCR; Stress