Follicle pool, ovarian surgery and the risk for a subsequent trisomic pregnancy

Novel insights into reproductive ageing and menopause from genomics

The post-reproductive phase or menopause in females is triggered by a physiological timer that depends on a threshold of follicle number in the ovary. Curiously, reproductive senescence appears to be decoupled from chronological age and is instead thought to be a function of physiological ageing. Ovarian ageing is associated with a decrease in oocyte developmental competence, attributed to a concomitant increase in meiotic errors. Although many biological hallmarks of general ageing are well characterized, the precise mechanisms underlying the programmed ageing of the female reproductive system remain elusive. In particular, the molecular pathways linking the external menopause trigger to the internal oocyte chromosome segregation machinery that controls fertility outcomes is unclear. However, recent large scale genomics studies have begun to provide insights into this process. Next-generation sequencing integrated with systems biology offers the advantage of sampling large datasets to uncover molecular pathways associated with a phenotype such as ageing. In this mini-review, we discuss findings from these studies that are crucial for advancing female reproductive senescence research. Targets identified in these studies can inform future animal models for menopause. We present three potential hypotheses for how external pathways governing ovarian ageing can influence meiotic chromosome segregation, with evidence from both animal models and molecular targets revealed from genomics studies. Although still in incipient stages, we discuss the potential of genomics studies combined with epigenetic age acceleration models for providing a predictive toolkit of biomarkers controlling menopause onset in women. We also speculate on future research directions to investigate extending female reproductive lifespan, such as comparative genomics in model systems that lack menopause. Novel genomics insights from such organisms are predicted to provide clues to preserving female fertility.

An Oxidative Stress-Related Gene Signature in Granulosa Cells Is Associated with Ovarian Aging

Ovarian aging is associated with a decrease in fecundity. Increased oxidative stress of granulosa cells (GCs) is an important contributor. We thus asked whether there is an oxidative stress-related gene signature in GCs associated with ovarian aging. Public nonhuman primate (NHP) single-cell transcriptome was processed to identify GC cluster. Then, a GC signature for ovarian aging was established based on six oxidative stress-related differentially expressed genes (MAPK1, STK24, AREG, ATG7, ANXA1, and PON2). Receiver operating characteristic (ROC) analysis confirmed good discriminating capacity in both NHP single-cell and human bulk transcriptome datasets. Gene expression levels were investigated using qPCR in the human ovarian granulosa-like tumor cell line (KGN) and mouse GCs. In an oxidative stress model, KGN cells were treated with menadione (7.5 μM, 24 h) to induce oxidative stress, after which upregulation of MAPK1, STK24, ATG7, ANXA1, and PON2 and downregulation of AREG were observed (p < 0.05). In an aging model, KGN cells were continuously cultured for 3 months, leading to increased expressions of all genes (p < 0.05). In GCs of reproductively aged (8-month-old) Kunming mice, upregulated expression of Mapk1, Stk24, Atg7, and Pon2 and downregulated expression of Anxa1 and Areg were observed (p < 0.01). We therefore here identify a six-gene GC signature associated with oxidative stress and ovarian aging.

Correlation between aneuploidy pregnancy and the concentration of various hormones and vascular endothelial factor in follicular fluid as well as the number of acquired oocytes

Objective To investigate the correlation between aneuploidy pregnancy and the concentration of various hormones and vascular endothelial factor in follicular fluid as well as the number of acquired oocytes and to provide a scientific basis for improving ovulation induction programs. Methods In total, we collected 277 follicular fluid specimens from patients undergoing in vitro fertilization (IVF) treatment in our hospital. Eighteen cases of aneuploidy embryos were identified. The follicular fluid of these aneuploidy embryos was used for the study. According to the case and control 1:5 paired design, we selected five age-matched controls with healthy births following IVF for each aneuploidy case. Concentrations of anti-Müllerian hormone (AMH), follicle-stimulating hormone (FSH), luteinizing hormone (LH), estrogen (E2) and vascular endothelial growth factor (VEGF) in the follicular fluid were measured. Conditional logistic regression was used to analyze the relationship between aneuploidy pregnancy and the concentrations of various hormones and VEGF in the follicular fluid as well as the number of acquired oocytes. Results Multivariate conditional logistic regression showed that of all the factors analyzed, only FSH [odds ratio (OR) = 1.300, 95% confidence interval (CI), 1.091-1.548, P = 0.003] level in the follicular fluid and the number of acquired oocytes (OR = 1.179, 95% CI, 1.070-1.299, P = 0.001) were closely related to aneuploidy pregnancy. No other factors were found to be associated with aneuploidy pregnancy. Conclusion FSH concentrations in the follicular fluid are risk factors for aneuploidy pregnancies. The higher the number of eggs, the higher the risk of aneuploidy. These findings may help improve ovulation induction programs.