Gene expression profiles of vitrified in vitro- and in vivo-derived bovine blastocysts

Vitrification is becoming a preferred method for pre-implantation embryo cryopreservation. The objective of this study was to determine the differentially expressed genes of in vivo- and in vitro-produced bovine embryos after vitrification. In vitro- (IVF) and in vivo-derived (IVV) bovine blastocysts were identified as follows: in vitro-produced fresh (IVF-F), in vitro-produced vitrified (IVF-V), in vivo-derived fresh (IVV-F), in vivo-derived vitrified (IVV-V). The microarray results showed that 53 genes were differentially regulated between IVF and IVV, and 121 genes were differentially regulated between fresh and vitrified blastocysts (P < 0.05). There were 6, 268, 962, and 17 differentially regulated genes between IVF-F × IVV-F, IVF-V × IVV-V, IVF-F × IVF-V, and IVV-F × IVV-V, respectively (P < 0.05). While gene expression was significantly different between fresh and vitrified IVF blastocysts (P < 0.05), it was similar between fresh and vitrified IVV blastocysts. Significantly up-regulated KEGG pathways included ribosome, oxidative phosphorylation, spliceosome, and oocyte meiosis in the fresh IVF blastocyst samples, while sphingolipid and purine metabolisms were up-regulated in the vitrified IVF blastocyst. The results showed that in vitro bovine blastocyst production protocols used in this study caused no major gene expression differences compared to those of in vivo-produced blastocysts. After vitrification, however, in vitro-produced blastocysts showed major gene expression differences compared to in vivo blastocysts. This study suggests that in vitro-produced embryos are of comparable quality to their in vivo counterparts. Vitrification of in vitro blastocysts, on the other hand, causes significant up-regulation of genes that are involved in stress responses.