In vitro fertilisation and vitrification disrupt embryo mitochondrial function and redox balance that persists into adulthood in mice

Abstract

Background and aimsAssisted reproductive technologies (ART), including in vitro fertilisation (IVF), account for over 10 million births worldwide. ART-conceived young offspring show altered cardiovascular phenotypes, including cardiac remodelling and raised blood pressure, but the mechanisms remain unclear. Mitochondrial disturbance during preimplantation development may link early ART exposure to later cardiac dysfunction. However, to our knowledge, no one has assessed mitochondrial function in adult offspring from IVF pregnancies. In this study, investigated the effects of IVF and embryo vitrification on blastocyst mitochondrial redox balance and metabolism, and determined whether these effects persisted into the adult heart. Methods and ResultsIGS-CD1 mouse blastocysts from naturally mated donors or IVF were transferred fresh or after vitrification-warming. IVF reduced blastocyst total, trophectoderm and inner cell mass cell number, while vitrification lowered the inner cell mass proportion and increased apoptosis. Both exposures depolarised mitochondrial membrane potential and depleted glutathione; reactive oxygen species rose with an interaction, being highest in vitrified IVF embryos. IVF reduced live birth rate and litter size. In the adult offspring, high-resolution respirometry of isolated mitochondria from left ventricle revealed reduced oxidative phosphorylation capacity with an increased H2O2 production, altered OXPHOS subunit abundance and reduced complex I, III and IV activities. ConclusionsIVF and vitrification impose distinct disturbance on preimplantation embryo redox states and bioenergetics, and this early disturbance is followed into adulthood with a reduced mitochondrial aerobic capacity and increased basal ROS production. These results have important implications for IVF practices and suggest that mitochondria may be permanently programmed by this procedure. Graphical Summary O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=105 SRC="FIGDIR/small/744765v1_ufig1.gif" ALT="Figure 1"> View larger version (47K): org.highwire.dtl.DTLVardef@1cd1bd7org.highwire.dtl.DTLVardef@ded6b8org.highwire.dtl.DTLVardef@1e2ddf7org.highwire.dtl.DTLVardef@15abc84_HPS_FORMAT_FIGEXP M_FIG C_FIG IVF and vitrification impose distinct and partly independent effects on the preimplantation embryo that persist into the adult offspring heart. At the blastocyst stage, IVF reduced cell number and vitrification altered lineage allocation, while both exposures lowered mitochondrial membrane potential ({Delta}{Psi}m) and glutathione (GSH) and raised reactive oxygen species (ROS); vitrification additionally increased apoptosis. After embryo transfer, IVF reduced live birth rate and litter size, whereas vitrification altered postnatal growth trajectory. In adult offspring, ventricular mitochondria, vitrification reduced OXPHOS capacity and IVF reduced LEAK respiration, while both exposures increased H2O2/ O2 flux, reduced respiratory chain enzyme activities and altered OXPHOS subunit abundance.