Molecular fingerprint of female bovine embryos produced in vitro with high competence to establish and maintain pregnancy

Abstract

The objective was to identify the transcriptomic profile of in vitro-derived embryos with highcompetence to establish and maintain gestation. Embryos produced with X-sorted sperm werecultured from day 5 to day 7 in serum-free medium containing 10 ng/ml recombinant bovinecolony-stimulating factor 2 (CSF2) or vehicle. The CSF2 was administered because this moleculecan increase blastocyst competence for survival after embryo transfer. Blastocysts were harvestedon day 7 of culture and manually bisected. One demi-embryo from a single blastocyst wastransferred into a synchronized recipient and the other half was used for RNA-seq analysis. UsingP < 0.01 and a fold change >2-fold or <0.5 fold as cutoffs, there were 617 differentially expressedgenes (DEG) between embryos that survived to day 30 of gestation vs those that did not, 470DEG between embryos that survived to day 60 and those that did not, 432 DEG between embryosthat maintained pregnancy from day 30 to day 60 vs those where pregnancy failed after day 30,and 635 DEG regulated by CSF2. Pathways and ontologies in which DEG were overrepresentedincluded many related to cellular responses to stress and cell survival. It was concluded that geneexpression in the blastocyst is different between embryos that are competent to establish andmaintain pregnancy vs those that are not. The relationship between expression of genes relatedto cell stress and subsequent embryonic survival probably reflects cellular perturbations causedby embryonic development taking place in the artificial environment associated with cell culture.