Effects of polyethylene glycol and a synthetic ice blocker during vitrification of immature porcine oocytes on survival and subsequent embryo development

Abstract

We evaluated the effects of polyethylene glycol (PEG) and Supercool X-1000 (SC) as supplements during the vitrification of immature cumulus-enclosed porcine oocytes in a solution based on 17.5% ethylene glycol + 17.5% propylene glycol. After warming, the oocytes were subjected to in vitro maturation, fertilization and embryo culture. In Experiment 1, equilibration and vitrification solutions were supplemented with or without 2% (w/v) PEG (PEG+ and PEG-, respectively). The survival rate, cleavage and blastocyst development were similar between PEG+ and PEG- groups; however, all values were lower than those in the non-vitrified control. In Experiment 2, vitrification solution was supplemented with or without 1% (v/v) SC (SC+ and SC-, respectively). The percentages of survival and blastocyst development were similar between SC+ and SC- groups but lower than those in the non-vitrified control. The percentage of cleavage in the SC- group was significantly lower than the control and the SC+ groups, which were in turn similar to one another. In both experiments, the cell numbers in blastocysts were not significantly different among the non-vitrified and vitrified groups. In conclusion, PEG did not improve oocyte survival and embryo development, whereas SC improved the ability of surviving oocytes to cleave but not to develop into blastocysts.

Supplementing Maturation Medium With Insulin Growth Factor I and Vitrification-Warming Solutions With Reduced Glutathione Enhances Survival Rates and Development Ability of in vitro Matured Vitrified-Warmed Pig Oocytes

“…Furthermore, vitrified pig oocytes have higher levels of reactive oxygen species (ROS) than their fresh counterparts (Gupta et al, 2010). As a result, developmental competence of pig oocytes is seriously affected by vitrification (Wu et al, 2013; Santos et al, 2017). Therefore, oxidative stress during pig oocyte vitrification and warming results in DNA damage and impairs fertilization and embryonic development (Galeati et al, 2011; Wu et al, 2013; Spricigo et al, 2017).…”

Cryopreservation of equine oocytes: looking into the crystal ball

“…Similarly, synthetic ice blockers are copied from naturally occurring glycoproteins or proteins and are believed to mitigate heterogeneous nucleation by recognition of ice nucleators or perhaps ice itself (Wowk et al 2000). Their use resulted in improved survival rates in vitrified murine embryos (Fahy et al 2004;Badrzadeh et al 2010) and survival and cleavage rates in porcine oocytes (Macedo et al 2006;Santos et al 2017). In equine oocytes, the addition of synthetic ice blockers in the vitrification media has also been tried, such as Supercool X-1000, a copolymer of polyvinyl alcohol, which improved maturation rates of vitrified-warmed oocytes (Curcio et al 2014b).…”

Low-Molecular-Weight PEGs for Cryopreservation of Stem Cell Spheroids

“…Polyethylene glycol (PEG) is a safe substance for human use and has been found to be effective in cryopreserving bacteriophages, microorganisms, and individual cells [ 26 – 29 ]. When added with DMSO during cryopreservation, PEG has also been found to improve the survival of mouse and porcine oocytes [ 30 , 31 ]. Recently, PEG coacervate was reported as a very effective cryoprotectant for stem cells [ 21 ].…”