Nanoparticles graphene effects, as a new cryoprotectant, on the quality of vitrified-warmed mouse blastocyst

Background and ObjectiveSince the first vitrification of mouse embryos in 1985, considerable efforts have been made to develop and improve cryopreservation techniques. Optimization of vitrification method requires dealing with several damaging factors including osmotic shock, cytotoxicity, detrimental effect of ice crystallization and heat shock. Vitrification under specific conditions of high concentration of cryoprotective agents and ultra-rapid cooling is used to preserve embryos derived from ARTs. Due to specific importance of ultra-rapid transition of temperature in minimizarion of ice crystal formation, a variety of cryodevices have been prospered for reduction of cryosolution volume to overcome the thermal resistance, however no study has yet considered thermal conductivity (TC) of vitrification solusions. Effects of supporting materials during vitrification procedure for decreasing heat shock caused the first time used graphene due to the high TC, high molecular weight and non-penetrating into the cell, as a cryoprotectant material instead of sucrose.We have developed a new vitrification solution that has clear advantages over others. While the vitrification solution with sucrose is hyperosmolar and there is probability a risk of osmotic shock, graphene-based media due to low viscosity and approximately isotonic conditions can significantly minimize the risk of osmotic shock. Therefore, it seems that application of graphene as an alternative to sucrose has more scientific justification.Materials and Methods:For this purpose, the first part of the experiment was conducted to determine the optimum concentration of graphene in vitrification and warming solutions. The second part was designed to compare the effect of graphene-based selected solutions and sucrose-based one in terms of survival, hatching and implantation rate.Findings:Among different concentrations of graphene, optimum concentrations of 1.5 and 4 M were chosen for vitrification and thawing mediums, respectively. Results of the second part demonstrated that not only the survival rate can be equal with sucrose by using graphene, but it also brings about as good results as the sucrose-based group regarding the hatching rate and more importantly the implantation rate.Conclusion: Due to the proximity of the blastocyst embryo survival rates between the two groups, after the warming process it can be introduced as an appropriate non-permeating cryoprotectant in order to optimize the process of freezing.

Keywords:

vitrification , non-permeating cryoprotectant , heat shock , thermal conductivity , mouse blastocyst