title: l-carnitine supplementation during vitrification of mouse germinal vesicle stage-oocytes and their subsequent in vitro maturation improves meiotic spindle configuration and mitochondrial distribution in metaphase II oocytes.
abstract: OBJECTIVE
  How does l-carnitine (LC) supplementation during vitrification and in vitro maturation (IVM) of germinal vesicle stage (GV)-oocytes improve the developmental competence of the resultant metaphase II (MII) oocytes?
  
  
  CONCLUSIONS
  LC supplementation during both vitrification of GV-oocytes and their subsequent IVM improved nuclear maturation as well as meiotic spindle assembly and mitochondrial distribution in MII oocytes.
  
  
  BACKGROUND
  Vitrification of GV-oocytes results in a lower success rate of blastocyst development compared with non-vitrified oocytes. LC supplementation during both vitrification and IVM of mouse GV-oocytes significantly improves embryonic development after IVF.
  
  
  METHODS
  GV-oocytes were collected from (B6.DBA)F1 and B6 mouse strains and subjected to vitrification and warming with or without 3.72 mM LC supplementation. After IVM with or without LC supplementation, the rate of nuclear maturation and the quality of MII oocytes were evaluated. At least 20 oocytes/group were examined, and each experiment was repeated at least three times. All experiments were conducted during 2013-2014.
  
  
  METHODS
  Extrusion of the first polar body in IVM oocytes was observed as an indication of nuclear maturation. Spindle assembly and chromosomal alignment were examined by immunostaining of α-tubulin and nuclear staining with 4,6-diamidino-2-phenylindole (DAPI). Mitochondrial distribution and oxidative activity were measured by staining with Mitotracker Green Fluorescence Mitochondria (Mitotracker Green FM) and chloromethyltetramethylrosamine (Mitotracker Orange CMTMRos), respectively. ATP levels were determined by using the Bioluminescent Somatic Cell Assay Kit.
  
  
  RESULTS
  LC supplementation during both vitrification and IVM of GV-oocytes significantly increased the proportions of oocytes with normal MII spindles to the levels comparable with those of non-vitrified oocytes in both mouse strains. While vitrification of GV-oocytes lowered the proportions of MII oocytes with peripherally concentrated mitochondrial distribution compared with non-vitrified oocytes, LC supplementation significantly increased the proportion of such oocytes in the (B6.DBA)F1 strain. LC supplementation decreased the proportion of oocytes with mitochondrial aggregates in both vitrified and non-vitrified oocytes in the B6 strain. The oxidative activity of mitochondria was mildly decreased by vitrification and drastically increased by LC supplementation irrespective of vitrification in both mouse strains. No change was found in ATP levels irrespective of vitrification or LC supplementation. Results were considered to be statistically significant at P < 0.05 by either χ(2)- or t-test.
  
  
  CONCLUSIONS
  It remains to be tested whether beneficial effect of LC supplementation during vitrification and IVM of GV-oocytes leads to fetal development and birth of healthy offspring after embryo transfer to surrogate females.
  
  
  CONCLUSIONS
  This protocol has the potential to improve the quality of vitrified human oocytes and embryos during assisted reproduction treatment.
  
  
  BACKGROUND
  Partially supported by the Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery Grant and Mitacs Elevate Postdoctoral Fellowship, Canada.
authors.affiliation: Department of Obstetrics and Gynecology, McGill University, Montreal, Quebec, Canada Department of Surgery, McGill University, Montreal, Quebec, Canada OriginElle Fertility Clinic and Women's Health Centre, Montreal, Quebec, Canada Department of Theriogenology, Faculty of Veterinary Medicine, Cairo University, Giza, Egypt.
authors.forename: Adel R
authors.initials: AR
authors.lastname: Moawad
authors.affiliation: Department of Surgery, McGill University, Montreal, Quebec, Canada OriginElle Fertility Clinic and Women's Health Centre, Montreal, Quebec, Canada.
authors.forename: Baozeng
authors.initials: B
authors.lastname: Xu
authors.affiliation: Department of Obstetrics and Gynecology, McGill University, Montreal, Quebec, Canada OriginElle Fertility Clinic and Women's Health Centre, Montreal, Quebec, Canada.
authors.forename: Seang Lin
authors.initials: SL
authors.lastname: Tan
authors.affiliation: Department of Obstetrics and Gynecology, McGill University, Montreal, Quebec, Canada Department of Surgery, McGill University, Montreal, Quebec, Canada OriginElle Fertility Clinic and Women's Health Centre, Montreal, Quebec, Canada Department of Biology, McGill University, Montreal, Quebec, Canada teruko.taketo@mcgill.ca.
authors.forename: Teruko
authors.initials: T
authors.lastname: Taketo
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002331:Carnitine / Q000494:pharmacology*; D018929:Cell Culture Techniques; D005260:Female; D059471:In Vitro Oocyte Maturation Techniques; D008297:Male; D008677:Metaphase / Q000187:drug effects*; D051379:Mice; D008811:Mice, Inbred DBA; D008928:Mitochondria / Q000187:drug effects* / Q000648:ultrastructure; D009865:Oocytes / Q000254:growth & development; D008941:Spindle Apparatus / Q000187:drug effects* / Q000648:ultrastructure; D058989:Vitrification
chemical_list: D000255:Adenosine Triphosphate; D002331:Carnitine
keywords: IVM; l-carnitine; mitochondria; oocyte; vitrification