Transcriptional profiling reveals upregulation of p53 signaling in porcine embryos produced in vitro

Although advances in the porcine embryo culture system have been achieved, the artificial environment continues to be stressful for the embryos, which hinders development. To identify areas of improvement, transcriptional profiling was performed on in vivo-derived, in vivo-matured and in vitro-cultured, and in vitro-matured and cultured porcine blastocyst-stage embryos. Numerous differentially expressed genes were detected between in vitro-cultured vs in vivo-derived (489 downregulated, 701 upregulated), in vitro-matured and cultured vs in vivo-derived (435 downregulated, 1124 upregulated), and in vitro-matured and cultured vs in vitro-cultured (32 downregulated, 168 upregulated). Moreover, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed upregulation of the p53 signaling pathway in vitro-matured and cultured embryos compared to in vivo-derived embryos. Therefore, in vitro-matured and cultured embryos were cultured with different p53 inhibitors, pifithrin-alpha, pifithrin-beta, or pifithrin-mu, to determine if the stress response could be suppressed to improve development to the blastocyst stage. Culture with 50 μM pifithrin-alpha improved development to the blastocyst stage (P < 0.05), but total cell number and transcript abundance of p53 target genes remained unaltered. No difference in development was observed after culturing embryos with pifithrin-beta, and embryos cultured with pifithrin-mu demonstrated decreased development. Lastly, two embryo transfers of embryos cultured with pifithrin-alpha demonstrated that the inhibitor did not disrupt developmental competence. Overall, the addition of pifithrin-alpha in the porcine embryo culture medium was shown to have beneficial effects on development and is suitable for generating live pigs with this system.