Effect of antifreeze protein supplementation in vitrification medium on mouse oocyte developmental competence

ObjectiveTo investigate the effect of antifreeze protein (AFP) supplementation during mouse oocyte vitrification on the survival, fertilization and embryonic development.DesignAnimal study.SettingUniversity laboratory.Animal(s)BDF-1 mice.Intervention(s)In vivo–matured metaphase II oocytes were vitrified with the use of CryoTop by two-step exposure to equilibrium and vitrification solution supplemented or not with 500 ng/mL AFP III.Main Outcome Measure(s)Postwarming survival, fertilization, embryonic development up to blastocyst in vitro, morphology of spindle and chromosome, membrane integrity, adenosine triphosphate (ATP) contents, and several gene expressions.Result(s)In the AFP-treated group, blastocyst formation rate was significantly higher and blastomere count with positive caspase was significantly lower compared with the nontreated group. Rate of intact spindle/chromosome, stable membrane, and ATP contents were significantly higher in AFP group. AFP group showed higher Mad2 and lower Eg5 gene expression. Both vitrification groups showed increased Hsf1, Zar1, and Zp1/Zp2 expression and decreased Hook1 and Zp3 expression compared with fresh control samples.Conclusion(s)Supplementation of AFP in vitrification medium has a protective effect on mouse oocytes for chilling injury; it can preserve spindle/membrane integrity and intracellular ATP contents. More stable spindle integrity in the AFP group may be associated with higher Mad2 and lower Eg5 gene expression.