Impaired Oocyte Quality Research Articles

Optimal aspiration pressure of suction pump for oocyte retrieval in infertile patients undergoing in vitro fertilization.

The oocyte retrieval is a critical step in assisted reproductive technologies, including in vitro fertilization and fertility preservation. Despite evolving techniques, the optimal aspiration pressure during retrieval remains debatable, with limited in vivo human studies. Existing studies, primarily in vitro and on animals, suggest that inappropriate aspiration pressures can impair oocyte quality. This study aims to compares the effects of two different aspiration pressures, 120mmHg and 150mmHg, on oocyte recovery, damage, and subsequent embryo development and pregnancy outcomes in infertile women undergoing transvaginal ultrasound-guided oocyte retrieval. This retrospective study analyzed data from 891 women at Seoul National University Hospital between May 2018 and August 2023. A total of 400 cycles were included, with 202 at 120 mmHg and 198 at 150 mmHg aspiration pressures. The primary outcomes were the number of retrieved, matured, fractured oocytes, embryos, and good-grade embryos. Pregnancy outcomes were evaluated by comparing the clinical pregnancy rates and live birth rates. Univariate and multivariate logistic regression analyses were conducted to evaluate the relationship between aspiration pressure, clinical pregnancy, and live birth rates. There was statistically significant difference in the number of retrieved oocytes and mature oocytes between the 120 mmHg group and the 150 mmHg group (6.3±5.2 vs. 7.7±6.7, p = 0.018; 4.4±3.7 vs. 5.6±5.3, p = 0.011). The number of embryos and good grade embryos also differed significantly (3.3±3.1 vs. 4.2±3.9, p = 0.011; 1.0±1.6 vs. 1.5±2.6, p = 0.031). However, there were no significant differences in clinical pregnancy and live birth rates between the two groups in multivariate logistic regression analysis (adjusted OR = 0.725, p = 0.519; adjusted OR = 0.370, p = 0.170). Increasing the aspiration pressure to 150mmHg led to a higher yield of oocytes and embryos than 120mmHg, without any negative impact on oocyte quality or live birth rates. These findings provide valuable insights for clinical decision-making in infertility treatments, suggesting that 150mmHg may be a more effective pressure for oocyte retrieval in in vitro fertilization and embryo transfer.

Ustiloxin A impairs oocyte quality by disrupting organelles function.

Oocyte quality is pivotal for fertilization and early embryonic development. Ustiloxin A (UA), is an emerging mycotoxin that has been frequently detected in rice and paddy. Because UA has been reported to be phytotoxic and cytotoxic, it poses a potential hazard to human and animal health. However, the effects of UA on oocyte maturation remain unknown. Here, we investigated the effects of acute UA exposure on mouse oocyte maturation. First, UA exposure inhibited oocyte maturation in a concentration-dependent manner and induced meiotic arrest by disrupting spindle assembly and reducing actin density. Moreover, mitochondrial function was substantially disrupted in oocytes upon UA exposure. Aberrant mitochondrial distribution, substantial downregulation of mitochondrial dynamics-associated genes Mfn1, Mfn2 and Fis1, decreased membrane potential and TOM20 expression were observed in UA-exposed oocytes; these effects further led to oxidative stress and DNA damage. Furthermore, UA induced ER and Golgi dysfunction and triggered ER stress by increasing GRP78 expression, which ultimately resulted in autophagy and early apoptosis in oocytes. Therefore, these results demonstrate that UA impairs oocyte quality by disrupting organelles function, providing new insight into the influence of UA on female reproduction in mammals.

Aging oocytes: exploring apoptosis and its impact on embryonic development in common carp (Cyprinus carpio).

Ovulation, fertilization, and embryo development are orchestrated and synchronized processes essential for the optimal health of offspring. Postovulatory aging disrupts this synchronization and impairs oocyte quality. In addition, oocyte aging causes fertilization loss and poor embryo development. This investigation aimed to unravel the endpoint of in vitro oocyte aging in common carp (Cyprinus carpio) to understand the involvement of apoptosis in postovulatory oocyte death. It was observed that the fertilization ability significantly declined (P < 0.001) at 8-h poststripping (HPS), subsequently triggering apoptosis in the advanced stage of oocyte aging, i.e., 48 HPS. This process included an increase in proapoptotic transcripts (fas, bax, cathepsin D, caspase 8, caspase 9, and caspase 3a) (P < 0.05), elevated levels of caspase 3 protein (P < 0.05), and activation of caspase 3 enzyme (P < 0.001), a key player in apoptosis, in aging oocytes. Furthermore, the effects of oocyte aging on the embryonic apoptosis machinery were examined in embryos at 5-h postfertilization (HPF) and 24 HPF derived from fresh and aged oocytes. Expression of apoptotic genes and caspase enzyme activity remained at the basal level in 5 HPF (early blastula embryos) from both fresh and aged oocytes. In contrast, the zymogenic and active forms of caspase 3 increased in 24 HPF embryos from 8-h-aged oocytes (P < 0.01) compared with those from fresh oocytes. Thus, apoptosis intensified in 24 HPF embryos from aged oocytes without affecting the apoptotic machinery of early blastula embryos. Our findings demonstrate that apoptosis initiated by the Fas/FasL system is an important physiological process accompanying oocyte aging in common carp.

Gestational exposure to arsenic reduces female offspring fertility by impairing the repair of DNA double-strand breaks and synapsis formation in oocytes

Arsenic is a pollutant that can cross the placenta; however, research on the effects of arsenic exposure during pregnancy on the fertility of female offspring is limited. To address this gap, we developed a mouse model to investigate the relationship between arsenic exposure during pregnancy and fertility in female offspring. Our fertility assessment revealed that gestational exposure to 1mg/kg arsenic or higher (10mg/kg) resulted in reduction in litter size, ovarian volume, and multistage-follicle number in female offspring. By assessing the in vitro developmental capacity of oocytes and zygotes, we confirmed that the reduced fertility was due not to impaired oocyte quality but rather to a reduction in oocyte quantity. Arsenic exposure impedes synapsis formation in MPI and compromises homologous recombination-mediated repair of double-strand breaks, resulting in fewer crossovers. This disruption activates the pachytene-checkpoint, hindering the progression of the MPI and resulting in the elimination of defective oocytes through p-Chk2 activation. Our study reveals for the first time the detrimental effects of arsenic exposure during pregnancy on the fertility of female offspring, underscoring the urgent need to prevent such exposure to safeguard reproductive health.

Polyethylene microplastic exposure adversely affects oocyte quality in human and mouse.

Microplastics (MPs) are pervasive environmental contaminants, resulting in unavoidable human exposure. This study identified MPs in follicular fluid and investigated the specific MPs and mechanisms that adversely affect oocytes. MPs in the follicular fluid of 44 infertile women undergoing assisted reproductive technology were measured using Raman microspectroscopy. Differential metabolites in follicular fluid were analyzed via untargeted metabolomics. Female mice were exposed to polyethylene (PE) to validate human findings. MPs, particularly PE, exhibited the highest detection rate (86.4%) in human follicular fluid and showed a negative correlation with fertilization rates (r=-0.407, P=0.007). Elevated PE levels altered metabolites primarily involved in metabolic pathways, ferroptosis, and ovarian steroidogenesis. In mice, PE exposure significantly reduced the number of retrieved oocytes (31.5 vs. 36.3, P < 0.05) and fertilization rate (70.8% vs. 85.2%, P < 0.001), while increasing the proportion of poor-quality oocytes (28.2% vs. 16.5%, P < 0.001) and reactive oxygen species (ROS) production compared to controls. RNA sequencing indicated significant upregulation of inflammation-related genes (Il10ra, Il1a, Il33, Tnfaip8l2, and Tnfrsf1b) in the PE-exposed group. In conclusion, PE exposure impairs oocyte quality possibly by disrupting follicular fluid metabolism, elevating inflammation-related gene expression, and increasing ROS production in oocytes.

Bisphenol S impairs oocyte quality by inducing gut microbiota dysbiosis.

Oocyte development is vulnerable to stimulation by intrinsic and extrinsic factors, particularly many environmental pollutants and chemicals in daily life. The reproductive toxicity of bisphenol S has been of great concern, although it is widely used as a safe substitute for its analog bisphenol A. However, it is not known how bisphenol S impairs oocyte quality. This work presents the exciting finding that bisphenol S induces gut microbiota dysbiosis, which further leads to increased intestinal permeability and inflammation and ultimately damages oocytes. More importantly, we show that alginate oligosaccharide improves gut homeostasis by reshaping the gut microbiota, therefore preventing the bisphenol S-induced gut microbiota dysbiosis and gut and oocyte damage. These findings present a major advance in the understanding of bisphenol S toxicity to oocytes and also provide a preventive strategy.

Damage mechanisms of bisphenols on the quality of mammalian oocytes.

The extensive use of bisphenols in the plastics industry globally is a major growing concern for human health. Bisphenol compounds are easily leached out from plastic containers to food, beverages, and drinking water and contaminate the natural environment. Daily exposure of bisphenol compounds increases their load and impairs various organs, including the reproductive system. Bisphenol compounds directly or indirectly affect ovarian functions, such as folliculogenesis, steroidogenesis, oogenesis, and thereby oocyte quality. Bisphenol A (BPA) and its structural analogues act as endocrine disruptors and induce generation of reactive oxygen species (ROS) within the ovary. Excess levels of ROS induce death pathways in follicular steroidogenic cells and affect ovarian steroidogenesis. The reduced level of estradiol-17β impairs follicular growth and development that reduces the number and quality of oocytes. In addition, excess levels of ROS in follicular fluid trigger meiotic instability, which further deteriorates oocyte quality. The high level of ROS generates oxidative stress that triggers various death pathways in germ cells as well as in oocytes, induces follicular atresia, and depletes ovarian reserve. Although growing evidence indicates the destructive effects of bisphenol compounds at the level of ovary, potential effects and underlying mechanisms that deteriorate oocyte quality remain poorly understood. Therefore, this review summarizes the mechanisms by which bisphenols cause damage to the ovary, impair oocyte quality, and affect women's fertility.

Age-associated accumulation of RAB9 disrupts oocyte meiosis.

The critical role of some RAB family members in oocyte meiosis has been extensively studied, but their role in oocyte aging remains poorly understood. Here, we report that the vesicle trafficking regulator, RAB9 GTPase, is essential for oocyte meiosis and aging in humans and mice. RAB9 was mainly located at the meiotic spindle periphery and cortex during oocyte meiosis. In humans and mice, we found that the RAB9 protein level were significantly increased in old oocytes. Age-related accumulation of RAB9 inhibits first polar body extrusion and reduces the developmental potential of oocytes. Further studies showed that increased Rab9 disrupts spindle formation and chromosome alignment. In addition, Rab9 overexpression disrupts the actin cap formation and reduces the cortical actin levels. Mechanically, Rab9-OE increases ROS levels, decreases mitochondrial membrane potential, ATP content and the mtDNA/nDNA ratio. Further studies showed that Rab9-OE activates the PINK1-PARKIN mitophagy pathway. Importantly, we found that reducing RAB9 protein expression in old oocytes could partially improve the rate of old oocyte maturation, ameliorate the accumulation of age-related ROS levels and spindle abnormalities, and partially rescue ATP levels, mtDNA/nDNA ratio, and PINK1 and PARKIN expression. In conclusion, our results suggest that RAB9 is required to maintain the balance between mitochondrial function and meiosis, and that reducing RAB9 expression is a potential strategy to ameliorate age-related deterioration of oocyte quality.

Excess Weight Impairs Oocyte Quality, as Reflected by mtDNA and BMP-15.

This prospective, case-control study evaluated the impact of obesity on oocyte quality based on mtDNA expression in cumulus cells (CC), and on bone morphogenetic protein 15 (BMP-15) and heparan sulfate proteoglycan 2 (HSPG2) in follicular fluid (FF). It included women 18 to <40 years of age, divided according to BMI < 24.9 (Group 1, n = 28) and BMI > 25 (Group 2, n = 22). Demographics, treatment, and pregnancy outcomes were compared. The mtDNA in CC, BMP-15, HSPG2, the lipid profile, the hormonal profile, and C-reactive protein were evaluated in FF and in blood samples. The BMP-15 levels in FF and the mitochondrial DNA in CC were higher in Group 1 (38.8 ± 32.5 vs. 14.3 ± 10.8 ng/mL; p = 0.001 and 1.10 ± 0.3 vs. 0.87 ± 0.18-fold change; p = 0.016, respectively) than in Group 2. High-density lipoprotein levels in blood and FF were higher in Group 1 (62 ± 18 vs. 50 ± 12 mg/dL; p = 0.015 and 34 ± 26 vs. 20.9 ± 7.2 mg/dL; p = 0.05, respectively). Group 2 had higher blood C-reactive protein (7.1 ± 5.4 vs. 3.4 ± 4.3 mg/L; p = 0.015), FF (5.2 ± 3.8 vs. 1.5 ± 1.6 mg/L; p = 0.002) and low-density lipoprotein levels (91 ± 27 vs. 71 ± 22 mg/dL; p = 0.008) vs. Group 1. Group 1 demonstrated a trend toward a better clinical pregnancy rate (47.8% vs. 28.6%: p = 0.31) and frozen embryo transfer rate (69.2% vs. 53.8; p = 0.69). Higher BMI resulted in lower BMP-15 levels and reduced mtDNA expression, which reflect decreased oocyte quality in overweight women.

Genetic Landscape of a Cohort of 120 Patients with Diminished Ovarian Reserve: Correlation with Infertility.

Diminished ovarian reserve (DOR) and primary ovarian insufficiency (POI) are major causes of female infertility. We recently found a monogenic etiology in 29.3% of POI, leading to personalized medicine. The genetic landscape of DOR is unknown. A prospective study (2018-2023) of an international cohort of 120 patients with unexplained DOR was performed using a large custom targeted next-generation sequencing panel including all known POI-causing genes. The diagnostic yield, based on the American College of Medical Genetics, was 24, 2%. Genes belong to different pathways: metabolism and mitochondria (29.7%), follicular growth (24.3%), DNA repair/meiosis (18.9%), aging (16.2%), ovarian development (8.1%), and autophagy (2.7%). Five genes were recurrently found: LMNA, ERCC6, SOX8, POLG, and BMPR1B. Six genes identified in single families with POI were involved in DOR, GNAS, TGFBR3, XPNPEP2, EXO1, BNC1, ATG, highlighting their role in maintaining ovarian reserve. In our cohort, 26 pregnancies were recorded, but no pregnancy was observed when meiosis/DNA repair genes were involved, suggesting severely impaired oocyte quality. Additional studies should confirm these preliminary results. This study with a large NGS panel defines the genetic landscape of a large cohort of DOR. It supports routine genetic diagnosis. Genetics could be a biomarker predicting infertility and progression to POI.

Advanced maternal age affects their frozen-thawed embryo susceptibility to high oxygen environment

Preimplantation embryos can experience stress from laboratory interventions and a sub-optimal culture environment. Though research has demonstrated advanced maternal age impairs oocyte quality, the response of embryos derived from such oocytes to vitrification-thawing and culture in a high oxygen (O2) environment in the assisted reproductive technology laboratory is unknown. Therefore, in this study, embryos produced by in vitro fertilization (IVF) using oocytes from two- and eight-month-old Swiss albino mice were vitrified and thawed during their 6–8 cell stage. and cultured at low oxygen (5%) tension (LOT) and high oxygen (20%) tension (HOT). Embryo development, apoptosis, inner cell mass (ICM) outgrowth proliferation ability in vitro and pluripotency were assessed. Embryos from advanced maternal age cultured at HOT showed reduced fertilizing ability (p < 0.05), poor survival post-thawing (p < 0.05), and increased apoptosis (p < 0.01) in comparison to sibling embryos cultured at LOT. Importantly, the extended culture of vitrified-thawed embryos from advanced maternal age led to a significant (p < 0.001) reduction in complete ICM outgrowth formation at HOT in comparison to the LOT environment. The findings of this study suggest that HOT is detrimental to embryos from advanced maternal age, and importantly, vitrified-thawed embryos are more susceptible to stress, which could have negative implications, especially during the peri-implantation developmental period.

Melatonin partially rescues defects induced by tranexamic acid exposure during oocyte maturation in mice.

Tranexamic acid (TXA) is widely used among young women because of its ability to whiten skin and treat menorrhagia. Nevertheless, its potential effects on oocyte maturation and quality have not yet been clearly clarified. Melatonin (MT) is an endogenous hormone released by the pineal gland and believed to protect cells from oxidative stress injury. In the present study, we used an in vitro maturation model to investigate the toxicity of TXA and the protective role of MT in mouse oocytes. Compared with the control group, the TXA-exposed group had significantly lower nuclear maturation (57.72% vs. 94.08%, P < 0.001) and early embryo cleavage rates (38.18% vs. 87.66%, P < 0.001). Further study showed that spindle organization (52.56% vs. 18.77%, P < 0.01) and chromosome alignment (33.23% vs. 16.66%, P < 0.01) were also disrupted after TXA treatment. Mechanistically, we have demonstrated that TXA induced early apoptosis of oocytes (P < 0.001) by raising the level of reactive oxygen species (P < 0.001), which was consistent with an increase in mitochondrial damage (P < 0.01). Fortunately, all these effects except the spindle defect were successfully rescued by an appropriate level of MT. Collectively, our findings indicate that MT could partially reverse TXA-induced oocyte quality deterioration in mice by effectively improving mitochondrial function and reducing oxidative stress-mediated apoptosis.NEW & NOTEWORTHY Tranexamic acid is increasingly used to whiten skin, reverse dermal damages, and treat heavy menstrual bleeding in young women. However, its potential toxicity in mammalian oocytes is still unclear. Our study revealed that tranexamic acid exposure impaired the mouse oocyte quality and subsequent embryo development. Meanwhile, melatonin has been found to exert beneficial effects in reducing tranexamic acid-induced mitochondrial dysfunction and oxidative stress.

Polystyrene nanoplastics induce apoptosis, autophagy, and steroidogenesis disruption in granulosa cells to reduce oocyte quality and fertility by inhibiting the PI3K/AKT pathway in female mice

BackgroundNanoplastics (NPs) are emerging pollutants that pose risks to living organisms. Recent findings have unveiled the reproductive harm caused by polystyrene nanoparticles (PS-NPs) in female animals, yet the intricate mechanism remains incompletely understood. Under this research, we investigated whether sustained exposure to PS-NPs at certain concentrations in vivo can enter oocytes through the zona pellucida or through other routes that affect female reproduction.ResultsWe show that PS-NPs disrupted ovarian functions and decreased oocyte quality, which may be a contributing factor to lower female fertility in mice. RNA sequencing of mouse ovaries illustrated that the PI3K-AKT signaling pathway emerged as the predominant environmental information processing pathway responding to PS-NPs. Western blotting results of ovaries in vivo and cells in vitro showed that PS-NPs deactivated PI3K-AKT signaling pathway by down-regulating the expression of PI3K and reducing AKT phosphorylation at the protein level, PI3K-AKT signaling pathway which was accompanied by the activation of autophagy and apoptosis and the disruption of steroidogenesis in granulosa cells. Since PS-NPs penetrate granulosa cells but not oocytes, we examined whether PS-NPs indirectly affect oocyte quality through granulosa cells using a granulosa cell–oocyte coculture system. Preincubation of granulosa cells with PS-NPs causes granulosa cell dysfunction, resulting in a decrease in the quality of the cocultured oocytes that can be reversed by the addition of 17β-estradiol.ConclusionsThis study provides findings on how PS-NPs impact ovarian function and include transcriptome sequencing analysis of ovarian tissue. The study demonstrates that PS-NPs impair oocyte quality by altering the functioning of ovarian granulosa cells. Therefore, it is necessary to focus on the research on the effects of PS-NPs on female reproduction and the related methods that may mitigate their toxicity.

Improved low-invasive mRNA electroporation method into immature mouse oocytes visualizes protein dynamics during development†.

One of the major causes of oocyte quality deterioration, chromosome segregation abnormalities manifest mainly during meiosis I, which occurs before and during ovulation. However, currently, there is a technical limitation in the introduction of mRNA into premature oocytes without impairing embryonic developmental ability. In this study, we established a low-invasive electroporation (EP) method to introduce mRNA into pre-ovulatory, germinal vesicle (GV) mouse oocytes in an easier manner than the traditional microinjection method. The EP method with an optimized impedance value resulted in the efficient introduction of mRNAs encoding enhanced green fluorescent protein (EGFP) into the GV oocytes surrounded by cumulus cells at a survival rate of 95.0%. Furthermore, the introduction of histone H2B-EGFP mRNA into the GV oocytes labeled most of the oocytes without affecting the blastocyst development rate, indicating the feasibility of the visualization of oocyte chromosomal dynamics that enable us to assay chromosomal integrity in oocyte maturation and cell count in embryonic development. The establishment of this EP method offers extensive assays to select pre-implantation embryos and enables the surveying of essential factors for mammalian oocyte quality determination.

Bisphenol M inhibits mouse oocyte maturation in vitro by disrupting cytoskeleton architecture and cell cycle processes

Bisphenol M (BPM), an alternative to bisphenol A (BPA), is commonly utilized in various industrial applications. However, BPM does not represent a safe substitute for BPA due to its detrimental effects on living beings. This research aimed to assess the influence of BPM exposure on the in vitro maturation of mouse oocytes. The findings revealed that BPM exposure had a notable impact on the germinal vesicle breakdown (GVBD) rate and polar body extrusion (PBE) rate throughout the meiotic progression of mouse oocytes, ultimately resulting in meiotic arrest. Investigations demonstrated that oocytes exposure to BPM led to continued activation of spindle assembly checkpoint. Further studies revealed that securin and cyclin B1 could not be degraded in BPM-exposed oocytes, and meiosis could not realize the transition from the MI to the AI stage. Mechanistically, BPM exposure resulted in abnormal spindle assembly and disrupted chromosome alignment of oocytes. Additionally, abnormal positioning of microtubule organizing center-associated proteins implied that MTOC may be dysfunctional. Furthermore, an elevation in the acetylation level of α-tubulin in oocytes was observed after BPM treatment, leading to decreased microtubule stability. In addition to its impact on microtubules, BPM exposure led to a reduction in the expression of the actin, signifying the disruption of actin assembly. Further research indicated a heightened incidence of DNA damage in oocytes following BPM exposure. Besides, BPM exposure induced alterations in histone modifications. The outcomes of this experiment demonstrate that BPM exposure impairs oocyte quality and inhibits meiotic maturation of mouse oocytes.

Glucose metabolism disorder related to follicular fluid exosomal miR-122-5p in cumulus cells of endometriosis patients.

Elevated expression of miR-122-5p in exosomes in the follicular fluid of patients with endometriosis impairs glucose metabolism in cumulus cells and may further impair oocyte quality. Endometriosis (EMs) affects fertility in women of childbearing age in many ways. The underlying mechanisms, including the decrease in oocyte quality, require further investigation. Exosomes, small vesicles responsible for intercellular information exchange, have been found to be involved in many biological events, including follicle development and oocyte meiosis recovery. From the perspective of follicular fluid exosomes, this study aimed to elucidate the mechanisms involved in EMs-related oocyte quality decline. Follicular fluid was collected from three groups of women: the untreated EMs group (EMs_UT), the satisfactorily treated EMs group (EMs_ST), and the control group (Ctrl). Mouse cumulus-oocyte complexes (COCs) were co-cultured with exosomes extracted from follicular fluid during in vitro maturation. Oocyte quality and cumulus cell function were assessed. High-throughput sequencing of miRNA in exosomes was conducted. The function of differentially expressed miRNAs was studied by using SVOG human ovarian granulosa cells transfected with an miRNA mimic and inhibitor. It was found that the follicular fluid exosomes from patients with untreated EMs reduced both the rate of maturation and the quality of mouse oocytes. Overexpression of miR-122-5p in untreated EMs inhibited the translation of key aldolase enzymes related to glucose metabolism and partly impaired glucose metabolism in the cumulus cells of patients with endometriosis. miR-122-5p was also observed to reduce proliferation and increase apoptosis after cell transfection with an miR-122-5p mimic and inhibitor. Further experiments are needed to determine whether there are additional small molecules in the follicular fluid of patients with endometriosis that could be involved in damaging oocyte quality and to identify where harmful substances in follicular fluid exosomes are loaded.

O-217 Evaluating the impact of obesity on oocyte quality, using 2 main factors in cumulus cells (CC) and follicular fluid (FF) which reflect oocyte quality

Abstract Study question How obesity impacts oocyte quality through analysis of mtDNA expression in CC and levels of proteins BMP-15 and HSPG2 in FF? Summary answer There is correlation between increased BMI and lower levels of BMP15 and a decreased expression of mtDNA that reflect decreased oocyte quality in overweight women. What is known already Obesity impacts female health and impairs fertility. There is limited evidence suggesting that obesity impairs oocyte quality. BMP-15 (Bone morphogenetic protein 15) is a protein synthesized by oocyte, is a factor predicting quality of the oocyte and female fertility. Heparan sulfate proteoglycan 2 (HSPG2) is a protein secreted from granulosa cells and there are limited studies regarding the function of HSPG2 in reproduction including oocyte quality. BMP-15 and HSPG2 secreted to FF. Oocyte quality was demonstrated to be influenced by mtDNA (mitochondrial DNA) content in CC. Study design, size, duration Prospective observational cohort study performed between February 2022 until June 2022 in a single university-affiliated hospital. Total of 50 patients were enrolled. Participants/materials, setting, methods Women who underwent IVF or ICSI cycles were included. Exclusion criteria were patients older than 40 years, fertility preservation, unbalanced endocrine disorders and less than 4 follicles at the time of OPU (oocyte pick-up). Follicular fluid and cumulus cells were collected following OPU. mtDNA was assessed by quantitative real-time PCR. BMP-15 and HSPG2 were measured with ELISA method quantitatively. Lipid profile, hormonal profile and C-reactive protein were evaluated in blood and follicular fluid samples. Main results and the role of chance Patients were divided based on BMI, 28 patients with BMI &amp;lt; 25 (Group 1) and 22 with BMI &amp;gt; 25 (Group 2). A significant increase in BMP-15 in FF (38.8 ± 32.5 vs. 14.3 ± 10.8 ng/ml; p = 0.001) and mitochondrial DNA in CC (1.10 ± 0.3 vs. 0.87 ± 0.18 Fold change expression; p = 0.016) were found in group 1. Significantly higher CRP in blood (7.1 ± 5.4 vs. 3.4 ± 4.3; p = 0.015) and FF (5.2 ± 3.8 vs. 1.5 ± 1.6; p = 0.002) and LDL level in blood (91 ± 27 vs. 71 ± 22; p = 0.008) in group 2. HDL levels were significantly higher in group 1 in the blood (50 ± 12 vs. 62 ± 18; p = 0.015) and FF (20.9 ± 7.2 vs. 34 ± 26; p = 0.05). The fresh clinical pregnancy rate demonstrated a trend toward better results in group 1 (47.8% vs. 28.6%: p = 0.31), as well as in FET (69.2% vs. 53.8; P = 0.69). Limitations, reasons for caution Research included relatively small number of participants. We can’t report our cumulative pregnancy rate since not all frozen embryos were transferred yet. Wider implications of the findings Obesity is an increasing worldwide problem and impairs fertility outcome. Our study demonstrates decreased oocyte quality in the group of overweight women through 2 important markers BMP-15 and mtDNA. We recommend our patients to lose weight and improve their lifestyle in order to overcome those impaired quality markers. Trial registration number Not applicable

P-684 Anti-müllerian hormone predictive value for cumulative pregnancy rate in non-infertile women following four intrauterine insemination with donor sperm

Abstract Study question Are anti-Müllerian hormone (AMH) levels predictive of cumulative pregnancy rate in non-infertile women undergoing intrauterine insemination with donor sperm (ds-IUI)? Summary answer AMH has limited predictive value for clinical pregnancy after 4 cycles of ds-IUI in non-infertile women. Decreased AMH concentration does not necessarily reduce pregnancy rates. What is known already Physiologically, pregnancy rates decline due to oocyte quality deterioration upon advancing maternal age. AMH is a widely-used marker of ovarian reserve and follicular response but not an infertility test, despite being sometimes referred to as such. This misconception can lead to unnecessary complex ART treatments only based on low AMH. Indeed, the predictive value of AMH for natural conception and IUI remains uncertain and highly controversial in the literature. Study design, size, duration This multicenter prospective observational study evaluated the correlation between AMH levels and pregnancy rates in 182 non-infertile women undergoing ds-IUI. Participants were recruited from June 2020 to December 2022 from three centers: Hospital del Mar in Barcelona (Spain), Fertty Clinic in Barcelona (Spain) and Clinica de la Mujer in Viña del Mar (Chile). Participants/materials, setting, methods The study included women aged 25-39 years, normal BMI, regular periods, and without ovarian pathology or endometriosis, who were undergoing ds-IUI for severe oligoasthenoteratozoospermia, female partner, or single status. Baseline AMH and antral follicle count (AFC) by TVUS was registered. Reproductive outcomes were compared between women with AMH &amp;gt;1.1 and AMH ≤1.1 ng/mL. The main outcome was the cumulative clinical pregnancy rate after up to 4 ds-IUIs in a 3-year frame. Main results and the role of chance Kaplan Meier’s analysis did not show cumulative pregnancy rate superiority in women with AMH &amp;gt;1.1 ng/mL vs &amp;lt; 1.1 ng/mL (log rank Mentel Cox 1,502; p-value 0.46; ROC curve analysis predictor for clinical pregnancy, AUC=0.586). AMH and AFC were found to be significantly correlated (Pearson’s coefficient r = 0.632, p-value &amp;lt;0.001). Additionally, women who achieved pregnancy were found to be significantly younger (p-value &amp;lt;0.05) versus women who did not. However, no differences in AMH levels were found between them (p-value 0.33). Limitations, reasons for caution Limitations of the study include interpretation of results in extreme concentrations of AMH, potential impact of polycystic ovary syndrome (PCOS) in women with high AMH values, lower representation of patients with low AMH levels, and variability in ovulation induction regimens prior to ds-IUI (exposure to different rFSH dosages). Wider implications of the findings AMH is not a reliable predictor for pregnancy in ds-IUI. Even women with extremely low AMH levels can achieve successful outcomes, which are associated with age. The results of this multicenter study support that low AMH should not be used as an exclusion criterion for non-infertile women seeking ds-IUI. Trial registration number IRB Protocol ID 2020/9445

The role of declining ataxia-telangiectasia-mutated (ATM) function in oocyte aging

Despite the advances in the understanding of reproductive physiology, the mechanisms underlying ovarian aging are still not deciphered. Recent research found an association between impaired ATM-mediated DNA double-strand break (DSB) repair mechanisms and oocyte aging. However, direct evidence connecting ATM-mediated pathway function decline and impaired oocyte quality is lacking. The objective of this study was to determine the role of ATM-mediated DNA DSB repair in the maintenance of oocyte quality in a mouse oocyte knockdown model. Gene interference, in vitro culture, parthenogenesis coupled with genotoxicity assay approaches, as well as molecular cytogenetic analyses based upon next-generation sequencing, were used to test the hypothesis that intact ATM function is critical in the maintenance of oocyte quality. We found that ATM knockdown impaired oocyte quality, resulting in poor embryo development. ATM knockdown significantly lowered or blocked the progression of meiosis in vitro, as well as retarding and reducing embryo cleavage after parthenogenesis. After ATM knockdown, all embryos were of poor quality, and none reached the blastocyst stage. ATM knockdown was also associated with an increased aneuploidy rate compared to controls. Finally, ATM knockdown increased the sensitivity of the oocytes to a genotoxic active metabolite of cyclophosphamide, with increased formation of DNA DSBs, reduced survival, and earlier apoptotic death compared to controls. These findings suggest a key role for ATM in maintaining oocyte quality and resistance to genotoxic stress, and that the previously observed age-induced decline in oocyte ATM function may be a prime factor contributing to oocyte aging.

Surfeit locus protein 4 modulates endoplasmic reticulum function and maintains oocyte quality

ABSTRACT Surfeit locus protein 4 is a cargo receptor mediating cargo transport from the endoplasmic reticulum lumen to the Golgi apparatus. Loss of Surf4 gene led to embryonic lethality in mice. However, the role of Surf4 during oocyte development remains unknown. In this study, we generated the mouse model with oocyte-specific knockout of Surf4 gene. We found that adult mice with deletion of Surf4 showed normal folliculogenesis, ovulation and fertility. However, loss of Surf4 slightly impaired oocyte quality, thus led to partial oocyte meiotic arrest and reduced ratio of blastocyst formation. Consistent with this, the distribution of endoplasmic reticulum was disturbed in Surf4-deficient oocytes in mice. These results demonstrated that although Surf4 is dispensable for female mouse fertility, Surf4 modulates endoplasmic reticulum arrangement and participates in regulation of developmental competence of oocytes.