Background:
Assisted reproductive technologies (ARTs), including in vitro culture and vitrification, are known to elicit changes in embryo and fetal gene expression. Previous studies have shown combined antioxidants (acetyl-L-carnitine/N-acetyl-L-cysteine/α-lipoic acid (A3)) in culture and vitrification media reduced the detrimental effects on embryo and fetal development. However, the mechanisms remain unclear therefore the effect of antioxidants on gene expression in mouse fetal tissues was examined.
Design:
Embryo transfers were conducted on in vivo flushed blastocysts, or blastocysts cultured or vitrified with and without A3. Transcriptional profiles of E14 fetal liver and placental tissue in all groups were quantified using RNAseq and functional analyses (KEGG).
Results:
Compared to in vivo derived embryos, in vitro culture altered the expression of 3601 fetal liver and 408 placental genes. Functional analysis showed upregulation/enrichment of oxidative phosphorylation and mitochondrial function and activity. Similarly, vitrification led to 2018 liver and 216 placental differentially expressed genes (DEGs). Upregulated KEGG pathways were enriched for cell and tissue development and cell cycle regulation. Down regulated pathways were associated with metabolism and immune response. Interestingly, A3 in culture media significantly reduced the number of DEGs (1855 liver and 4 placentae) with no KEGG pathways identified. Correspondingly, A3 in vitrification media reduced the number of DEGs to 1017 in liver and 206 in placentae. Functional pathway enrichment was similar to embryos vitrified without A3, although with decreased expression.
Conclusion:
Both in vitro culture under 20% oxygen and vitrification of blastocysts significantly perturbed fetal liver and placental gene expression, with the number of DEGs greater following vitrification. Antioxidants reduced the number of DEGs and biological processes altered, establishing a more in vivo like gene expression profile, particularly in the placenta. Notably, antioxidants significantly reduced gene expression associated with preeclampsia and intrauterine growth restriction which may help maintain the viability of vitrified human embryos.