The impact of melatonin-enriched media on epigenetic and perinatal changes induced by embryo culture in a mouse model

To determine if melatonin-enriched culture media could offset loss of imprinting in mouse concepti.

Zygotes were cultured to blastocyst stage under optimized conditions in melatonin-supplemented media at either 10^-9 M (MT 10^-9) or 10^-6 M (MT 10^-6), or without supplementation (Culture + embryo transfer, or ET, positive control). Blastocysts were also developed in vivo (ET negative control). All blastocysts were transferred to surrogate recipients. Concepti were assessed just prior to term. DNA methylation analysis for placenta, fetal brain, heart, and liver was performed with amplicon next generation sequencing for four imprinting control regions (ICRs): H19/Igf2, Kcnq1ot1, Peg3 and Snrpn.

Placental methylation was significantly different in the Culture + ET, MT 10^-9, and MT 10^-6 groups from ET at both Peg3 and H19/Igf2. At Snrpn and Kcnq1ot1 ICRs, the Culture + ET group was significantly differently methylated than ET, but MT groups were not significantly different from either control. Additionally, fetal hearts from both MT 10^-9 and Culture + ET groups were significantly hypomethylated compared to ET at the H19/Igf2 ICR, while MT 10^-6 was not significantly different. Methylation differences in experimental culture groups were also observed in fetal liver, but no differences were detected in fetal brain.

This is the first study to identify ICR DNA hypomethylation in fetal heart tissue with embryo culture, which is of interest due to increased cardiac anomalies in human IVF offspring. Although not completely restorative, both melatonin concentrations partially offset some methylation changes at ICRs in fetal placenta and heart.