Deirdre Zander-Fox

Women with reduced ovarian reserve or advanced maternal age have an altered follicular environment

OBJECTIVE To determine whether altered follicular environment is associated with ovarian reserve or maternal age. DESIGN Prospective study examining follicular fluid (FF) composition and follicular cell metabolism. SETTING University research department and private IVF clinic. PATIENT(S) Women (n = 54) undergoing routine IVF treatment were allocated to one of three groups based on ovarian reserve and maternal age. INTERVENTION(S) Surplus FF, granulosa cells (GC), and cumulus cells (CC) were collected. MAIN OUTCOME MEASURE(S) Follicular fluid concentrations of carbohydrates, hormones, and selected ions. Metabolic analysis and gene expression of GCs and CCs. RESULT(S) Compared to women <35 years with normal ovarian reserve, FF glucose levels were significantly decreased and lactate and progesterone (P4) concentrations significantly increased in women with reduced ovarian reserve or advanced maternal age, whereas GC and CC glucose uptake, lactate production, and phosphofructokinase platelet gene expression were significantly increased. Granulosa cell P4 production from women with reduced ovarian reserve or advanced maternal age was decreased; however, in CCs the reverse was observed with increased gene expression in P4 receptor, prostaglandin E receptor-2, cytosolic phospholipase A2, and tumor protein 53. CONCLUSION(S) Women with either reduced ovarian reserve or advanced maternal age have altered follicular cell metabolism, FF metabolites, and P4 production. This perturbed environment may be responsible for impaired oocyte developmental competence and subsequent embryo development.

Peri-conception parental obesity, reproductive health, and transgenerational impacts

Maternal over-nutrition during pregnancy is a risk factor for pregnancy complications and is increasingly associated with adverse childhood outcomes such as increased propensity for obesity and metabolic disease. However, there is emerging evidence that parental lifestyle factors prior to and at conception have a powerful impact on the health of the offspring for more than one generation. Maternal and paternal obesity prior to conception alters the molecular composition of both oocytes and sperm, which can partly escape epigenetic reprogramming at fertilization, altering the developmental trajectory of the resultant embryo, ultimately increasing the incidence of obesity and metabolic disorders in offspring. Understanding the molecular underpinning of these changes may help create interventions to reduce the risk of disease in future generations.

Oxidative Stress in Mouse Sperm Impairs Embryo Development, Fetal Growth and Alters Adiposity and Glucose Regulation in Female Offspring

Paternal health cues are able to program the health of the next generation however the mechanism for this transmission is unknown. Reactive oxygen species (ROS) are increased in many paternal pathologies, some of which program offspring health, and are known to induce DNA damage and alter the methylation pattern of chromatin. We therefore investigated whether a chemically induced increase of ROS in sperm impairs embryo, pregnancy and offspring health. Mouse sperm was exposed to 1500 µM of hydrogen peroxide (H2O2), which induced oxidative damage, however did not affect sperm motility or the ability to bind and fertilize an oocyte. Sperm treated with H2O2 delayed on-time development of subsequent embryos, decreased the ratio of inner cell mass cells (ICM) in the resulting blastocyst and reduced implantation rates. Crown-rump length at day 18 of gestation was also reduced in offspring produced by H2O2 treated sperm. Female offspring from H2O2 treated sperm were smaller, became glucose intolerant and accumulated increased levels of adipose tissue compared to control female offspring. Interestingly male offspring phenotype was less severe with increases in fat depots only seen at 4 weeks of age, which was restored to that of control offspring later in life, demonstrating sex-specific impacts on offspring. This study implicates elevated sperm ROS concentrations, which are common to many paternal health pathologies, as a mediator of programming offspring for metabolic syndrome and obesity.

Does obesity really matter? The impact of BMI on embryo quality and pregnancy outcomes after IVF in women aged ≤38 years

The increasing prevalence of obesity in women of child‐bearing age is of growing concern in the health community. Obesity is associated with sub‐optimal reproductive performance; therefore, it is understandable that the number of young women with elevated body mass index (BMI) accessing assisted reproductive treatment (ART) is on the rise. Consequently, this study not only assessed the impact of BMI on fertilisation rates, embryo development and freezing during ART in women aged ≤38 years but also determined their subsequent pregnancy and delivery rates.

Single blastocyst embryo transfer maintains comparable pregnancy rates to double cleavage-stage embryo transfer but results in healthier pregnancy outcomes

Background:  The optimal outcome after IVF is a live, healthy, singleton term baby. This can be achieved by transferring a single embryo, but at the possible expense of reducing pregnancy rates. Recent studies suggest that delaying transfer of embryos to the blastocyst stage (day 4/5), rather than the more traditional cleavage stage (day 2–3), allows for better selection of the best embryo, maximising pregnancy rates from a single embryo transfer (SET). The aim of this study was to assess pregnancy outcomes in relation to changing embryo transfer practices.

Stimulation of mitochondrial embryo metabolism by dichloroacetic acid in an aged mouse model improves embryo development and viability

OBJECTIVE To determine whether supplementation of embryo culture media with a substrate to stimulate mitochondrial activity improves embryo viability and pregnancy establishment in aged mice. DESIGN Female mice were superovulated and mated. Zygotes were collected and cultured in either G1/G2 or G1/G2 with 1.0 mM dichloroacetic acid (DCA), a stimulator of pyruvate dehydrogenase complex. Embryos were cultured to the blastocyst stage and transferred into pseudopregnant female mice. SETTING University research facility. ANIMAL(S) Swiss female mice 26- to 28-week-old. INTERVENTION(S) The addition of DCA to the embryo culture media. MAIN OUTCOME MEASURE(S) Embryo development, total, trophectoderm, inner cell mass (ICM) and epiblast cell number, mitochondrial membrane potential, reactive oxygen species, pyruvate oxidation, adenosine triphosphate (ATP) output, implantation rates, and fetal and placental size and weights. RESULT(S) Supplementation of the embryo culture medium with DCA significantly increased blastocyst development rates in vitro, significantly improved total, trophectoderm, and ICM cell numbers and pluripotency of the ICM, significantly increased pyruvate oxidation and ATP output, and significantly increased fetal weights and size comparable to in vivo conditions. CONCLUSION(S) This study demonstrates that the addition of DCA to embryo culture media improves mitochondrial output in embryos produced from aged mice. Although DCA itself may be of limited therapeutic value in a clinical setting due to its low threshold of dosage and high toxicity, this proof of concept study does suggest that the addition of a physiological-based mitochondrial stimulator to embryo culture media for aged women may potentially improve IVF outcomes.

Mitochondrial SIRT5 is present in follicular cells and is altered by reduced ovarian reserve and advanced maternal age.

Women with reduced ovarian reserve or advanced maternal age have an altered metabolic follicular microenvironment. As sirtuin 5 (SIRT5) senses cellular metabolic state and post-translationally alters protein function, its activity may directly impact on oocyte viability and pregnancy outcome. Therefore, we investigated the role of SIRT5 in relation to ovarian reserve and maternal age. Women (n=47) undergoing routine IVF treatment were recruited and allocated to one of three cohorts based on ovarian reserve and maternal age. Surplus follicular fluid, granulosa and cumulus cells were collected. SIRT5 mRNA, protein and protein activity was confirmed in granulosa and cumulus cells via qPCR, immunohistochemistry, western blotting and desuccinylation activity. The presence of carbamoyl phosphate synthase I (CPS1), a target of SIRT5, was investigated by immunohistochemistry and follicular-fluid ammonium concentrations determined via microfluorometry. Women with reduced ovarian reserve or advanced maternal age had decreased SIRT5 mRNA, protein and desuccinylation activity in granulosa and cumulus cells resulting in an accumulation of follicular-fluid ammonium, presumably via alterations in activity of a SIRT5 target, CPS1, which was present in granulosa and cumulus cells. This suggests a role for SIRT5 in influencing oocyte quality and IVF outcomes.

Reduction of Mitochondrial Function by FCCP During Mouse Cleavage Stage Embryo Culture Reduces Birth Weight and Impairs the Metabolic Health of Offspring

ABSTRACT The periconceptual environment represents a critical window for programming fetal growth trajectories and susceptibility to disease; however, the underlying mechanism responsible for programming remains elusive. This study demonstrates a causal link between reduction of precompaction embryonic mitochondrial function and perturbed offspring growth trajectories and subsequent metabolic dysfunction. Incubation of embryos with carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone (FCCP), which uncouples mitochondrial oxidative phosphorylation, significantly reduced mitochondrial membrane potential and ATP production in 8-cell embryos and the number of inner cell mass cells within blastocysts; however, blastocyst development was unchanged. This perturbed embryonic mitochondrial function was concomitant with reduced birth weight in female offspring following embryo transfer, which persisted until weaning. FCCP-treated females also exhibited increased adiposity at 4 wk, increased adiposity gain between 4 and 14 wk, glucose intolerance at 8 wk, and insulin resistance at 14 wk. Although FCCP-treated males also exhibited reduced glucose tolerance, but their insulin sensitivity and adiposity gain between 4 and 14 wk was unchanged. To our knowledge, this is one of the first studies to demonstrate that reducing mitochondrial function and, thus, decreasing ATP output in the precompacting embryo can influence offspring phenotype. This is of great significance as a large proportion of patients requiring assisted reproductive technologies are of advanced maternal age or have a high body mass index, both of which have been independently linked with perturbed early embryonic mitochondrial function.

The most common vices of men can damage fertility and the health of the next generation

Animal and human studies demonstrate that acquired paternal traits can impair both a males fertility and the health of his offspring, including advanced age, smoking, stress, trauma, under-nutrition, infection, toxin exposure, and obesity. Many of these factors lead to similar changes to neurological, behavioural, and/or metabolic functioning in offspring. The molecular mechanisms that both respond to the paternal environment and act to transmit traits to offspring are beginning to emerge. This review focuses on three vices of men (alcohol consumption, overweight/obesity, and tobacco smoking) that damage fertility and pose risks to offspring health. These vices are not only the three most prevalent but are also leading risk factors for death and disability adjusted life years (DALYs) worldwide. Moreover, given that these vices are predominantly self-inflicted, interventions aimed at mitigating their consequences are readily identified.

The Future of Human Embryo Culture Media – Or Have We Reached the Ceiling?

Within the embryology laboratory one of the central components is embryo culture media. The fundamental goal/role of the laboratory and therefore the culture media has been to maintain the inherent viability of the gametes/embryos before replacement to the mother. Over the last 10-15 years there have been major advancements in this area, with culture media developing from simple salt solutions into highly complex defined media, specifically designed to reduce stress to the embryo and maintain high pregnancy rates. As a direct result of these advancements in culture media formulation and increased awareness of the contribution of QA/QC, single embryo transfer is now a realistic outcome for a majority of patients. Although the role of culture media in stress reduction and viability maintenance may have reached its ceiling, with likely only incremental increases in pregnancy rates to be made in the future, there may be a new role for culture media as a therapeutic device evolving from the goal of maintaining the inherent viability to improving the viability of the gametes and embryos.