PGE2 supplementation of oocyte culture media improves the developmental and cryotolerance performance of bovine blastocysts derived from a serum-free in vitro production system, mirroring the inner cell mass transcriptome

We focused our investigation of an embryo's response to different in vitro environments on changes to the transcriptomic profile of the inner cell mass (ICM), i.e. that part of the blastocyst giving rise to the epiblast and then to all future intraembryonic tissues. We used RNA-sequencing analysis to examine the gene expression of ICM derived under the different IVP conditions. The study evaluated the effects of a serum-free (SF) IVP system including defined oocyte culture media supplemented or not with PGE2, on gene expression of the ICM when compared with standard serum-containing (SC) IVP. Overall design: Cumulus-oocyte-complexes (COC) were randomly assigned to three in-vitro-produced (IVP) treatment groups : standard serum-containing conditions including the serum supplementation (“SC”), experimental serum-free IVP conditions (“SF”), and experimental serum-free IVP conditions associated with PGE2 supplementation (“SF + PGE2”). After a 22h maturation period, COC were transfered to embryo culture medium and incubated for 7 days to reach blastocyst stage. Four independent sessions of in vitro embryo production, each including the three IVP conditions were performed in order to produce pools (3, 4 and 4 for the “SC”, “SF” and “SF + PGE2” treatment groups, respectively) of 8 to 11 fresh dissected ICM. Their transcriptomic profiles were established by RNA sequencing.