Vitrification preserves chromatin integrity, bioenergy potential and oxidative parameters in mouse embryos
1 Veterinary Clinics and Animal Productions Unit, Department of Emergency and Organ Trasplantation (DETO), University of Bari Aldo Moro, Valenzano, Bari, Italy
2 Department of Bioscience, Biotechnology and Biopharmaceutics, University of Bari, Aldo Moro, Bari, Italy
3 Department and Clinic of Obstetrics and Reproduction, Szent Istvan University, Budapest, Hungary
Reproductive Biology and Endocrinology 2013, 11:27 doi:10.1186/1477-7827-11-27Published: 3 April 2013
The aim of this study was to evaluate the effects of vitrification on morpho-functional parameters (blastomere/chromatin integrity and bioenergy/oxidative potential) of mouse preimplantation embryos.
In vivo produced mouse (4/16-cell, morulae and blastocyst-stage) embryos were randomly divided into vitrification and control groups. For vitrification, embryos were exposed to a 2-step loading of ethylene glycol and propylene glycol, before being placed in a small nylon loop and submerged into liquid nitrogen. After warming, the cryoprotectants were diluted by a 3-step procedure. Embryo morphology, chromatin integrity and energy/oxidative status were compared between groups.
Vitrification induced low grade blastomere cytofragmentation (P < 0.05) and low chromatin damage only in embryos at the morula stage (P < 0.001). Mitochondrial (mt) distribution pattern was affected by vitrification only in early embryos (P < 0.001). Mitochondrial activity did not change upon vitrification in morula-stage embryos but it was reduced in blastocyst-stage embryos (P < 0.05). Intracellular ROS levels significantly increased in embryos at the morula and blastocyst stages (P < 0.001). Colocalization of active mitochondria and ROS increased only in vitrified blastocysts.
In conclusion, this study elucidates the developmentally-related and mild effects of vitrification on morphology, nuclear and bioenergy/oxidative parameters of mouse embryos and demonstrates that vitrification is a suitable method for preserving predictive parameters of embryo ability to induce a full-term pregnancy.