Moderate maternal folic acid supplementation ameliorates adverse embryonic and epigenetic outcomes associated with assisted reproduction in a mouse model

Abstract

Could clinically-relevant moderate and/or high dose maternal folic acid supplementation prevent aberrant developmental and epigenetic outcomes associated with assisted reproductive technologies (ART)?SUMMARY ANSWER: Our results demonstrate dose-dependent and sex-specific effects of folic acid supplementation in ART and provide evidence that moderate dose supplements may be optimal for both sexes.WHAT IS KNOWN ALREADY: Children conceived using ART are at an increased risk for growth and genomic imprinting disorders, often associated with DNA methylation defects. Folic acid supplementation is recommended during pregnancy to prevent adverse offspring outcomes; however, the effects of folic acid supplementation in ART remain unclear.STUDY DESIGN, SIZE, DURATION: Outbred female mice were fed three folic acid-supplemented diets, control (rodent daily recommended intake or DRI; CD), moderate (4-fold DRI; 4FASD) or high (10-fold DRI; 10FASD) dose, for six weeks prior to ART and throughout gestation. Mouse ART involved a combination of superovulation, in vitro fertilisation, embryo culture and embryo transfer.PARTICIPANTS/MATERIALS, SETTING, METHODS: Midgestation embryos and placentas (n = 74-99/group) were collected; embryos were assessed for developmental delay and gross morphological abnormalities and embryos and placentas were examined for epigenetic defects. We assessed methylation at four imprinted genes (Snrpn, Kcnq1ot1, Peg1 and H19) in matched midgestation embryos and placentas (n = 31-32/group) using bisulfite pyrosequencing. In addition, we examined genome-wide DNA methylation patterns in placentas (n = 6 normal placentas per sex/group) and embryos (n = 6 normal female embryos/group; n = 3 delayed female embryos/group) using reduced representation bisulfite sequencing (RRBS).MAIN RESULTS AND THE ROLE OF CHANCE: Moderate, but not high dose supplementation, was associated with a decrease in the proportion of developmentally delayed embryos. Although moderate dose folic acid supplementation reduced DNA methylation variance at certain imprinted genes in embryonic and placental tissues, high dose supplementation exacerbated the negative effects of ART at imprinted loci. Furthermore, folic acid supplements resolved female-biased aberrant imprinted gene methylation. Supplementation was more effective at correcting ART-induced genome-wide methylation defects in male versus female placentas; however, folic acid supplementation also led to additional methylation perturbations which were more pronounced in males.

Assisted reproductive technologies induce temporally specific placental defects and the preeclampsia risk marker sFLT1 in mouse

“…In addition to placenta overgrowth, IVF placentas exhibit biallelic expression of imprinted genes, which are normally monoallelically expressed, concomitant with loss of allele-specific DNA methylation of their regulatory imprinting control regions (ICRs) (de Waal et al, 2014;de Waal et al, 2015;Rahimi et al, 2019;Whidden et al, 2016). To ascertain whether an association exists between these DNA methylation changes and the morphological phenotypes over the span of placenta development, we measured DNA methylation of the paternally methylated ICR H19/Igf2 and three maternally methylated ICRs -Kcnq1ot1, Peg3 and Snrpnby bisulfite pyrosequencing.…”

Global DNA Methylation as a Potential Underlying Mechanism of Congenital Disease Development

“…Recent study examined the genome-wide DNA methylation patterns in placentas and embryos in correlation with maternal FA supplementation in the prevention of CAs associated with assisted reproductive technologies (ART). Results demonstrate dose-dependent and sex-specific effects of FA intake; moderate dose of FA supplements may be optimal in ART for both sexes [139]. Even more, recent data suggest that genome-wide DNA methylation in the placentas from preterm infants could be associated with maternal socioeconomic status [140].…”

The Effect of Dietary Folic Acid Supplementation on Female Germ Cell Aneuploidy

“…In our study, we showed that FA supplementation (8 mg/kg) has reduced the effect of aging on oocyte aneuploidy by significantly increasing the proportion of normal oocytes in old female mice fed the supplemented FA diet for 24-week. Also, a similar level of FA supplementation (8 mg/kg) was shown to be beneficial for mice undergoing ART by reducing embryonic developmental delay and loss (Rahimi et al, 2019). It should be noted that the 8 mg FA/day supplementation is comparable to the combined FA intake from both fortified foods and over-the-counter prenatal supplements.…”

“…In mice, it has been reported recently that ART use was associated with increased embryonic loss and developmental delay (Rahimi et al, 2019). A high incidence of aneuploidy has been reported in the abortuses of infertile patients who conceived pregnancy using ART (Lathi & Milki, 2004;Nayak et al, 2011) and this high incidence of aneuploidy was associated with advance maternal age (Kushnir & Frattarelli, 2009;Spandorfer et al, 2004).…”

“…Similarly, in women undergoing ART treatment, FA supplementation was associated with better quality and maturation of oocytes, better embryo quality, and higher fertilization (Berker et al, 2009;Czeizel et al, 2010;Gaskins et al, 2014a;Szymanski & Kazdepka-Zieminska, 2003;Westphal et al, 2006). Also, FA supplement intake was associated with reduced embryonic developmental delay and loss in mice undergoing ART (Rahimi et al, 2019). Since the proportion of women who delay pregnancy until increasingly older ages has increased and subsequently more couples are having infertility issues and pursuing ART interventions, there is concern that the incidence of oocyte aneuploidy and consequent disorders in the offspring will also increase.…”