Rescue of vitrified-warmed bovine mature oocytes by short-term recovery culture with resveratrol

Abstract

Resveratrol, a well-known antioxidant, has been reported to protect mouse metaphase-II (M − II) stage oocytes from vitrification injuries when used as a treatment during a series of vitrification processes. The present study was conducted to investigate whether short-term treatment of post-warm bovine mature oocytes with resveratrol can increase blastocyst formation rate following in vitro fertilization and culture. Bovine denuded M − II oocytes were vitrified-warmed using Cryotop® or nylon mesh (pore size = 37 μm) as a cryodevice. The post-warm oocytes were treated for 2 h with 1 μM resveratrol in recovery culture medium. The resveratrol treatment had no harmful influence on morphological survival and cleavage rate of the oocytes vitrified-warmed with Cryotop® or nylon mesh. In the Cryotop® vitrification series, blastocyst formation rate of resveratrol-treated post-warm oocytes (39.0%) was not significantly different from that of non-treated post-warm oocytes (31.7%). However in the nylon mesh vitrification series, there was a significant increase in the blastocyst yield (42.4% vs. 31.3%, P < 0.05) when post-warm oocytes were treated with resveratrol. Blastocyst yield from fresh control oocytes was 49%. Levels of reactive oxygen species were comparable between post-warm and fresh control M − II oocytes, and decreased in oocytes after recovery culture with resveratrol. Mitochondrial activity of post-warm oocytes was restored to the pre-vitrification level during the recovery culture regardless of resveratrol supplementation. Thus, short-term recovery culture with resveratrol can rescue bovine M − II oocytes vitrified-warmed on a nylon mesh cryodevice.