Cholesterol added prior to vitrification on the cryotolerance of immature and in vitro matured bovine oocytes

PLoS One. 2017 Sep 14;12(9):e0184714. doi: 10.1371/journal.pone.0184714. eCollection 2017.

Abstract

This study examines whether incorporating cholesterol-loaded methyl-β-cyclodextrin (CLC) in the bovine oocyte plasma membrane improves oocyte tolerance to vitrification. In vitro matured oocytes were incubated with 2 mg/ml BODIPY-labeled CLC for different time intervals in FCS or PVA supplemented medium or exposed to different CLC concentrations to examine the subcellular localization of cholesterol by confocal microscopy live-cell imaging. Subsequently, the effects of optimized CLC concentrations and incubation times prior to vitrification on early embryo development were assessed. Then, we evaluated the effects of pretreatment with 2 mg/ml CLC for 30 min before the vitrification of immature (GV) and in vitro matured (MII) oocytes on developmental competence and gene expression. Our results indicate a high plasma membrane labeling intensity after 30 min of incubation with 2 mg/ml CLC for 30 min, regardless of the holding medium used. When oocytes were incubated with 1 mg/ml, 2 mg/ml and 3 mg/ml of CLC, intense labeling was observed at the plasma membrane after 40, 30 and 20 min, respectively. CLC pre-treatment before the vitrification of bovine oocytes did not affect subsequent cleavage and embryo development rates irrespective of CLC concentrations, incubation times or meiotic stage. However, pretreatment seems to improve the quality of embryos derived from vitrified oocytes, mainly when oocytes were vitrified at the GV stage.

MeSH terms

  • Animals
  • Cattle
  • Cell Survival
  • Cholesterol / pharmacology*
  • Cryopreservation / methods*
  • Embryo Culture Techniques
  • Female
  • Gene Expression Regulation / drug effects
  • In Vitro Oocyte Maturation Techniques / methods*
  • Oocytes / drug effects*
  • Oocytes / physiology
  • Vitrification
  • beta-Cyclodextrins / pharmacology*

Substances

  • beta-Cyclodextrins
  • methyl-beta-cyclodextrin
  • Cholesterol

Grants and funding

This study was supported by: the Spanish Ministry of Science and Innovation (Project AGL2013–46769), http://www.idi.mineco.gob.es/portal/site/MICINN/menuitem.7eeac5cd345b4f34f09dfd1001432ea0/?vgnextoid=83b192b9036c2210VgnVCM1000001d04140aRCRD, to TM and MLB; The Generalitat de Catalunya (Project No. 2014 SGR 547), http://agaur.gencat.cat/en/inici/index.html, to TM and MLB; and NA was supported by FPU scholarship (FPU12-01419), http://www.mecd.gob.es/servicios-al-ciudadano-mecd/en/catalogo/general/educacion/998758/ficha.html. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.