Abstract
Advanced maternal age (AMA) is known to reduce fertility, increases aneuploidy in oocytes and early embryos and leads to adverse developmental consequences which may associate with offspring lifetime health risks. However, investigating underlying effects of AMA on embryo developmental potential is confounded by the inherent senescence present in maternal body systems further affecting reproductive success. Here, we describe a new model for the analysis of early developmental mechanisms underlying AMA by the derivation and characterisation of mouse embryonic stem cell (mESC-like) lines from naturally conceived embryos. Young (7-8 weeks) and Old (7-8 months) C57BL/6 female mice were mated with young males. Preimplantation embryos from Old dams displayed developmental retardation in blastocyst morphogenesis. mESC lines established from these blastocysts using conventional techniques revealed differences in genetic, cellular and molecular criteria conserved over several passages in the standardised medium. mESCs from embryos from AMA dams displayed increased incidence of aneuploidy following Giemsa karyotyping compared with those from Young dams. Moreover, AMA caused an altered pattern of expression of pluripotency markers (Sox2, OCT4) in mESCs. AMA further diminished mESC survival and proliferation and reduced the expression of cell proliferation marker, Ki-67. These changes coincided with altered expression of the epigenetic marker, Dnmt3a and other developmental regulators in a sex-dependent manner. Collectively, our data demonstrate the feasibility to utilise mESCs to reveal developmental mechanisms underlying AMA in the absence of maternal senescence and with reduced animal use.
Highlights
Mouse ESC lines were derived from E3.5 blastocysts of Young and Old dams and cultured on MMC-mouse embryonic fibroblasts (MEFs) in an mouse embryonic stem cell (mESC) medium
inner cell mass (ICM) outgrowths were cultured individually, and each mESC line was generated from an individual blastocyst
We have investigated the effects of Advanced maternal age (AMA) on mouse blastocyst development and the phenotype of undifferentiated mESCs derived from the ICM
Summary
Whilst there is a global trend for women to delay bearing children, several studies indicate that advanced maternal age (AMA) leads to reduced ovarian reserve and infertility[1] and increased risk of pregnancy complications including gestational diabetes,[2] preterm birth, hypertension and pre-eclampsia.[3,4,5] AMA has been shown to adversely affect human offspring cardiometabolic and mental health.[6,7]The loss of ovarian reserve with AMA is common in mammals and may coincide with increased aneuploidy due to a range of segregation errors during meiosis affecting spindle dynamics.[8,9,10] maternal senescence affects physiological conditions across cell types and organs; for example, uterine decidualisation is diminished by AMA in human and mouse, affecting placental activity and increasing pregnancy loss.[11,12] senescence from AMA may promote a chronic maternal immune response affecting diverse foetal organ function and health.[13]Given the confounding influence of maternal systemic senescence on AMA pregnancy success, models are required to understand the developmental potential of AMA oocytes and embryos and whether influenced or not by the extent and character of meiotic aneuploidy. Whilst there is a global trend for women to delay bearing children, several studies indicate that advanced maternal age (AMA) leads to reduced ovarian reserve and infertility[1] and increased risk of pregnancy complications including gestational diabetes,[2] preterm birth, hypertension and pre-eclampsia.[3,4,5] AMA has been shown to adversely affect human offspring cardiometabolic and mental health.[6,7]. The loss of ovarian reserve with AMA is common in mammals and may coincide with increased aneuploidy due to a range of segregation errors during meiosis affecting spindle dynamics.[8,9,10] maternal senescence affects physiological conditions across cell types and organs; for example, uterine decidualisation is diminished by AMA in human and mouse, affecting placental activity and increasing pregnancy loss.[11,12] senescence from AMA may promote a chronic maternal immune response affecting diverse foetal organ function and health.[13]. Human and mouse embryos show retarded development in AMA.[14,15] where
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