An investigation into the relationship between the metabolic profile of follicular fluid, oocyte developmental potential, and implantation outcome

Follicular Fluid Metabolomics: Tool for Predicting IVF Outcomes of Different Infertility Causes

Infertility affects approximately 15% of couples at child-bearing ages and assisted reproductive technologies (ART), especially in vitro fertilization and embryo transfer (IVF-ET), provided infertile patients with an effective solution. The current paradox is that multiple embryo transfer that may leads to severe obstetric and perinatal complications seems to be the most valid measure to secure high success rate in the majority of clinic centers. Therefore, to avoid multiple transfer of embryos, it is urgent to explore biomarkers for IVF prognosis to select high-quality oocytes and embryos. Follicular fluid (FF), a typical biofluid constituted of the plasma effusion and granulosa-cell secretion, provides essential intracellular substances for oocytes maturation and its variation in composition reflects oocyte developmental competence and embryo viability. With the advances in metabolomics methodology, metabolomics, as an accurate and sensitive analyzing method, has been utilized to explore predictors in FF for ART success. Although FF metabolomics has provided a great possibility for screening markers with diagnostic and predictive value, its effectiveness is still doubted by some researchers. This may be resulted from the ignorance of the impact of sterility causes on the FF metabolomic profiles and thus its predictive ability might not be rightly illustrated. Therefore, in this review, we categorically demonstrate the study of FF metabolomics according to specific infertility causes, expecting to reveal the predicting value of metabolomics for IVF outcomes.

Factors defining developmental competence of bovine oocytes collected for in vitro embryo production†

Despite the currently relatively low effectiveness of producing bovine embryos in vitro, there is a growing interest in applying this laboratory method in the field of reproduction. Many aspects of the procedure need to be improved. One of the main problems is the inferior developmental competence of in vitro matured oocytes that are collected using the ovum pick-up method. The mechanisms of oocyte capacitation and maturation, as well as the in vivo conditions in which they grow and mature, should be carefully analyzed. A deliberate application of the identified mechanisms and beneficial factors affecting the in vitro procedures seems to be essential for achieving higher developmental competence of the oocytes that are subjected to fertilization. The results may be improved by developing and employing a laboratory maturation protocol that corresponds with appropriate preparation of donors before the ovum pick-up, an optimized hormonal treatment program, the appropriate size of ovarian follicles at the time of aspiration, and a fine-tuned coasting period.

Preovulatory follicular fluid secretome added to in vitro maturation medium influences the metabolism of equine cumulus-oocyte complexes

BACKGROUND

In vitro embryo production is a highly demanded reproductive technology in horses, which requires the recovery (in vivo or post-mortem) and in vitro maturation (IVM) of oocytes. Oocytes subjected to IVM exhibit poor developmental competence compared to their in vivo counterparts, being this related to a suboptimal composition of commercial maturation media. The objective of this work was to study the effect of different concentrations of secretome obtained from equine preovulatory follicular fluid (FF) on cumulus-oocyte complexes (COCs) during IVM. COCs retrieved in vivo by ovum pick up (OPU) or post-mortem from a slaughterhouse (SLA) were subjected to IVM in the presence or absence of secretome (Control: 0 µg/ml, S20: 20 µg/ml or S40: 40 µg/ml). After IVM, the metabolome of the medium used for oocyte maturation prior (Pre-IVM) and after IVM (Post-IVM), COCs mRNA expression, and oocyte meiotic competence were analysed.

RESULTS

IVM leads to lactic acid production and an acetic acid consumption in COCs obtained from OPU and SLA. However, glucose consumption after IVM was higher in COCs from OPU when S40 was added (Control Pre-IVM vs. S40 Post-IVM: 117.24 ± 7.72 vs. 82.69 ± 4.24; Mean µM ± SEM; p < 0.05), while this was not observed in COCs from SLA. Likewise, secretome enhanced uptake of threonine (Control Pre-IVM vs. S20 Post-IVM vs. S40 Post-IVM: 4.93 ± 0.33 vs. 3.04 ± 0.25 vs. 2.84 ± 0.27; Mean µM ± SEM; p < 0.05) in COCs recovered by OPU. Regarding the relative mRNA expression of candidate genes related to metabolism, Lactate dehydrogenase A (LDHA) expression was significantly downregulated when secretome was added during IVM at 20-40 µg/ml in OPU-derived COCs (Control vs. S20 vs. S40: 1.77 ± 0.14 vs. 1 ± 0.25 vs. 1.23 ± 0.14; fold change ± SEM; p < 0.05), but not in SLA COCs.

CONCLUSIONS

The addition of secretome during in vitro maturation (IVM) affects the gene expression of LDHA, glucose metabolism, and amino acid turnover in equine cumulus-oocyte complexes (COCs), with diverging outcomes observed between COCs retrieved using ovum pick up (OPU) and slaughterhouse-derived COCs (SLA).

Physiological high temperatures alter the amino acid metabolism of bovine early antral follicles

Heat stress reduces the developmental competence of bovine oocytes during the growth phase; however, the detailed mechanisms remain unclear. Amino acids play various critical roles in follicular development, including protein synthesis and as energy sources. We performed in vitro growth (IVG) culture of oocyte-cumulus-granulosa complexes (OCGCs) to assess the amino acid metabolism of small follicles at high temperatures. We isolated OCGCs from early antral follicles (0.5-1.0 mm) and subjected them to IVG culture for 12 days. OCGCs in the heat shock group were cultured under a temperature cycle of (38.5°C: 5 h, 39.5°C: 5 h, 40.5°C: 5 h, and 39.5°C: 9 h) to reproduce the body temperature of lactating cows under a hot environment. OCGCs in the control group were cultured at a constant temperature of 38.5°C for 24 h. Of the surviving OCGCs, those showing similar morphology and size between the groups were selected for amino acid analysis. We analyzed the free amino acids and their metabolites in the culture medium and calculated the depletion or appearance of molecular species. The depletion of three essential amino acids (isoleucine, leucine, and valine), two non-essential amino acids (aspartic acid and glycine), and ornithine was higher in the heat shock group (P < 0.05). Alanine depletion was lower in the heat shock group (P < 0.05). We concluded that heat exposure alters the amino acid metabolism of OCGCs isolated from early antral follicles, which might be involved with the diminished developmental potential of oocytes during summer.

Metabolic signature of follicular fluid in infertility-related diseases: a narrative review

Metabolomics offers new methods to identify biomarkers for oocyte and embryo quality, and for a better understanding of the physiopathology of infertility. This review investigated the latest findings regarding metabolome-derived biomarkers in follicular fluid of women with the most common types of infertility, and the potential impact on reproductive medicine outcomes. PubMed was searched for publications on metabolomics and human follicular fluid, and key biomarkers, kinetics and relationships with infertility diseases were identified. A reduced concentration of glucose and increased concentrations of lactate and pyruvate were found in follicular fluid of patients with endometriosis and diminished ovarian reserve, and the opposite was found in patients with polycystic ovary syndrome. These signatures may lead to the hypothesis of changed metabolite concentrations in patients with endometriosis and diminished ovarian reserve, and a metabolic pathway alteration with decreased aerobic glycolysis in patients with polycystic ovary syndrome. However, the pattern found in patients with endometriosis and low responders may also be expected in follicular fluid of fertile women. Larger studies are needed to confirm the results. An international database may help to highlight follicular fluid biomarkers in order to improve the selection of cryopreserved oocytes, and to enrich culture medium to restore normal metabolism and improve reproductive treatment outcomes.

The Role of One-Carbon Metabolism and Methyl Donors in Medically Assisted Reproduction: A Narrative Review of the Literature

One-carbon (1-C) metabolic deficiency impairs homeostasis, driving disease development, including infertility. It is of importance to summarize the current evidence regarding the clinical utility of 1-C metabolism-related biomolecules and methyl donors, namely, folate, betaine, choline, vitamin B12, homocysteine (Hcy), and zinc, as potential biomarkers, dietary supplements, and culture media supplements in the context of medically assisted reproduction (MAR). A narrative review of the literature was conducted in the PubMed/Medline database. Diet, ageing, and the endocrine milieu of individuals affect both 1-C metabolism and fertility status. In vitro fertilization (IVF) techniques, and culture conditions in particular, have a direct impact on 1-C metabolic activity in gametes and embryos. Critical analysis indicated that zinc supplementation in cryopreservation media may be a promising approach to reducing oxidative damage, while female serum homocysteine levels may be employed as a possible biomarker for predicting IVF outcomes. Nonetheless, the level of evidence is low, and future studies are needed to verify these data. One-carbon metabolism-related processes, including redox defense and epigenetic regulation, may be compromised in IVF-derived embryos. The study of 1-C metabolism may lead the way towards improving MAR efficiency and safety and ensuring the lifelong health of MAR infants.

Analysis of the potential regulatory mechanisms of female and latent genital tuberculosis affecting ovarian reserve function using untargeted metabolomics

Female and latent genital tuberculosis (FGTB and LGTB) in young women may lead to infertility by damaging ovarian reserve function, but the regulatory mechanisms remain unclear. In this study, we investigated the effects of FGTB and LGTB on ovarian reserve function and potential regulatory mechanisms by untargeted metabolomics of follicular fluid, aiming to provide insights for the clinical management and treatment approaches for afflicted women. We recruited 19 patients with FGTB, 16 patients with LGTB, and 16 healthy women as a control group. Clinical data analysis revealed that both the FGTB and LGTB groups had significantly lower ovarian reserve marker levels compared to the control group, including lower anti-Müllerian hormone levels (FGTB: 0.82 [0.6, 1.1] μg/L; LGTB: 1.57 [1.3, 1.8] μg/L vs. control: 3.29 [2.9, 3.5] μg/L), reduced antral follicular counts (FGTB: 6 [5.5, 9.5]; LGTB: 10.5 [7, 12.3] vs. control: 17 [14.5, 18]), and fewer retrieved oocytes (FGTB: 3 [2, 5]; LGTB: 8 [4, 8.3] vs. control: 14.5 [11.5, 15.3]). Conversely, these groups exhibited higher ovarian response marker levels, such as longer gonadotropin treatment days (FGTB: 12 [10.5, 12.5]; LGTB: 11 [10.8, 11.3] vs. control: 10 [8.8, 10]) and increased gonadotropin dosage requirements (FGTB: 3300 [3075, 3637.5] U; LGTB: 3037.5 [2700, 3225] U vs. control: 2531.25 [2337.5, 2943.8] U). All comparisons were statistically significant at P < 0.05. The results suggested that FGTB and LGTB have adverse effects on ovarian reserve and response. Untargeted metabolomic analysis identified 92 and 80 differential metabolites in the control vs. FGTB and control vs. LGTB groups, respectively. Pathway enrichment analysis revealed significant alterations in metabolic pathways in the FGTB and LGTB groups compared to the control group (P < 0.05), with specific changes noted in galactose metabolism, biotin metabolism, steroid hormone biosynthesis, and nicotinate and nicotinamide metabolism in the FGTB group, and caffeine metabolism, primary bile acid biosynthesis, steroid hormone biosynthesis, and glycerophospholipid metabolism in the LGTB group. The analysis of metabolic levels has revealed the potential mechanisms by which FGTB and LGTB affect ovarian reserve function, namely through alterations in metabolic pathways. The study emphasizes the importance of comprehending the metabolic alterations associated with FGTB and LGTB, which is of considerable relevance for the clinical management and therapeutic approaches in afflicted women.

Exploring the mechanism of clomiphene citrate to improve ovulation disorder in PCOS rats based on follicular fluid metabolomics

To examine the effects of clomiphene citrate (CC) on follicular fluid metabolites and related metabolic pathways in rats with polycystic ovary syndrome (PCOS) using non-targeted metabolomics and determine how CC treats ovulation disorder in PCOS. The Sprague Dawley rats were randomly divided into control, model, and CC groups. A PCOS model was established with letrozole. Body weight, ovarian weight, estrus cycles, serum hormone levels, and ovary histopathology of the rats were collected for further evaluation. Moreover, through ultra-performance liquid chromatography-mass spectrometry, the study of follicular fluid metabolites revealed the mechanism of action of CC. CC reduced ovarian weight and regulated estrous cycles and serum hormone levels in PCOS rats but did not affect their body weight. Moreover, the metabolomic results showed that CC adjusted 153 metabolites, among which 16 cross metabolites like testosterone, androstenedione, 17α-hydroxyprogesterone, and cholic acid were considered as potential biomarkers for CC to improve ovulation disorders in PCOS rats. Kyoto Encyclopedia of Genes and Genomes pathway enrichment also showed that the CC group mainly engaged in tryptophan metabolism and steroid hormone biosynthesis. CC can improve ovulation disorders in rats, and its mechanism is related to the regulation of the secretion of serum hormone and follicular fluid metabolites and the amelioration of multi-metabolic pathways.

Metabolomic profiling of exosomes reveals age-related changes in ovarian follicular fluid

BACKGROUND

Female fertility declines with increased maternal age, and this decline is even more rapid after the age of 35 years. Follicular fluid (FF) is a crucial microenvironment that plays a significant role in the development of oocytes, permits intercellular communication, and provides the oocytes with nutrition. Exosomes have emerged as being important cell communication mediators that are linked to age-related physiological and pathological conditions. However, the metabolomic profiling of FF derived exosomes from advanced age females are still lacking.

METHODS

The individuals who were involved in this study were separated into two different groups: young age with a normal ovarian reserve and advanced age. The samples were analysed by using gas chromatography-time of flight mass spectrometry (GC-TOFMS) analysis. The altered metabolites were analysed by using Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis to identify the functions and pathways that were involved.

RESULTS

Our data showed that metabolites in exosomes from FF were different between women of young age and women of advanced age. The set of 17 FF exosomal metabolites (P ≤ 0.05) may be biomarkers to differentiate between the two groups. Most of these differentially expressed metabolites in FF were closely involved in the regulation of oocyte number and hormone levels.

CONCLUSIONS

In this study, we identified differences in the metabolites of exosomes from FF between women of young age and women of advanced age. These different metabolites were tightly related to oocyte count and hormone levels. Importantly, these findings elucidate the metabolites of the FF exosomes and provide a better understanding of the nutritional profiles of the follicles with age.

Recent progress in metabolomics for analyzing common infertility conditions that affect ovarian function

Background

Numerous efforts have been undertaken to identify biomarkers associated with embryo and oocyte quality to improve the success rate of in vitro fertilization. Metabolomics has gained traction for its ability to detect dynamic biological changes in real time and provide comprehensive metabolite profiles. This review synthesizes the most recent findings on metabolomic analysis of follicular fluid (FF) in clinical conditions leading to infertility, with a focus on the dynamics of energy metabolism and oocyte quality, and discusses future research directions.

Methods

A literature search was conducted without time constraints.

Main findings

The metabolites present in FF originate from five primary pathways: glycolysis, oxidative phosphorylation, lipid metabolism and β-oxidation, nucleic acid synthesis, and ketogenesis. Metabolomic profiling can broadly categorize infertile women into two groups: those with infertility due to aging and endometriosis, and those with infertility associated with polycystic ovarian syndrome and obesity. In the former group, glycolysis and lipid metabolism are upregulated to compensate for mitochondrial dysfunction, whereas the latter group exhibits the opposite trend. Assessing the levels of glucose, pyruvate, lactate, and plasmalogens in FF may be valuable for evaluating oocyte quality.

Conclusion

Metabolomic analysis, particularly focusing on energy metabolism in FF, holds promise for predicting female reproductive outcomes.

The metabolomic profile of endometrial receptivity in recurrent miscarriage

BACKGROUND

Endometrial receptivity has been the focus of continuous research for over eight decades; however, current clinical practice lacks an accurate test of endometrial receptivity to allow the prediction of successful pregnancy. We aimed to characterize the endometrial metabolomic profiles of women who suffered recurrent miscarriage using discovery metabolomics and to set the foundation for the development of an endometrial receptivity test.

METHODS

This was a prospective multicenter cohort study led by the Tommy's National Centre for Miscarriage Research in Birmingham. Endometrial biopsies were obtained during the window of implantation from 24 women aged 18-35 years, who were not pregnant and regularly menstruating, diagnosed with unexplained recurrent miscarriage. The metabolite composition and relative concentrations of samples were analyzed applying ultra-high performance liquid chromatography-mass spectrometry to investigate water-soluble and lipid metabolites.

RESULTS

Various metabolic perturbations are associated with observation of increased numbers of miscarriages. They relate to fatty acid metabolism including increased lipolysis and decreased medium chain fatty acid beta-oxidation, poorer mitochondrial health, and redox-active co-factors which are present at higher oxidative levels. Other metabolic perturbations are associated with observation of live birth following miscarriages. They relate to perturbed cholesterol-cholesterol sulphate metabolism, fatty acid metabolism including increased diacylglyceride lipolysis and decreased medium chain fatty acid beta-oxidation, and improved mitochondrial health.

CONCLUSIONS

The present endometrial metabolomics discovery studies have implicated a small number of metabolic pathways and biological functions which are biologically important in miscarriage mechanisms.

Potential factors result in diminished ovarian reserve: a comprehensive review

The ovarian reserve is defined as the quantity of oocytes stored in the ovary or the number of oocytes that can be recruited. Ovarian reserve can be affected by many factors, including hormones, metabolites, initial ovarian reserve, environmental problems, diseases, and medications, among others. With the trend of postponing of pregnancy in modern society, diminished ovarian reserve (DOR) has become one of the most common challenges in current clinical reproductive medicine. Attributed to its unclear mechanism and complex clinical features, it is difficult for physicians to administer targeted treatment. This review focuses on the factors associated with ovarian reserve and discusses the potential influences and pathogenic factors that may explain the possible mechanisms of DOR, which can be improved or built upon by subsequent researchers to verify, replicate, and establish further study findings, as well as for scientists to find new treatments.

Dehydroepiandrosterone supplementation and the impact of follicular fluid metabolome and cytokinome profiles in poor ovarian responders

BACKGROUND

Poor ovarian responders (POR) are women undergoing in-vitro fertilization who respond poorly to ovarian stimulation, resulting in the retrieval of lower number of oocytes, and subsequently lower pregnancy rates. The follicular fluid (FF) provides a crucial microenvironment for the proper development of follicles and oocytes through tightly controlled metabolism and cell signaling. Androgens such as dehydroepiandrosterone (DHEA) have been proposed to alter the POR follicular microenvironment, but the impact DHEA imposes on the FF metabolome and cytokine profiles is unknown. Therefore, the objective of this study is to profile and identify metabolomic changes in the FF with DHEA supplementation in POR patients.

METHODS

FF samples collected from 52 POR patients who underwent IVF with DHEA supplementation (DHEA +) and without (DHEA-; controls) were analyzed using untargeted liquid chromatography-tandem mass spectrometry (LC-MS/MS) metabolomics and a large-scale multiplex suspension immunoassay covering 65 cytokines, chemokines and growth factors. Multivariate statistical modelling by partial least squares-discriminant regression (PLSR) analysis was performed for revealing metabolome-scale differences. Further, differential metabolite analysis between the two groups was performed by PLSR β-coefficient regression analysis and Student's t-test.

RESULTS

Untargeted metabolomics identified 118 FF metabolites of diverse chemistries and concentrations which spanned three orders of magnitude. They include metabolic products highly associated with ovarian function - amino acids for regulating pH and osmolarity, lipids such fatty acids and cholesterols for oocyte maturation, and glucocorticoids for ovarian steroidogenesis. Four metabolites, namely, glycerophosphocholine, linoleic acid, progesterone, and valine were significantly lower in DHEA + relative to DHEA- (p < 0.05-0.005). The area under the curves of progesterone glycerophosphocholine, linoleic acid and valine are 0.711, 0.730, 0.785 and 0.818 (p < 0.05-0.01). In DHEA + patients, progesterone positively correlated with IGF-1 (Pearson r: 0.6757, p < 0.01); glycerophosphocholine negatively correlated with AMH (Pearson r: -0.5815; p < 0.05); linoleic acid correlated with estradiol and IGF-1 (Pearson r: 0.7016 and 0.8203, respectively; p < 0.01 for both). In DHEA- patients, valine negatively correlated with serum-free testosterone (Pearson r: -0.8774; p < 0.0001). Using the large-scale immunoassay of 45 cytokines, we observed significantly lower MCP1, IFNγ, LIF and VEGF-D levels in DHEA + relative to DHEA.

CONCLUSIONS

In POR patients, DHEA supplementation altered the FF metabolome and cytokine profile. The identified four FF metabolites that significantly changed with DHEA may provide information for titrating and monitoring individual DHEA supplementation.

Nontargeted metabolomics analysis of follicular fluid in patients with endometriosis provides a new direction for the study of oocyte quality

Endometriosis is a common, estrogen-dependent chronic gynecological disease that endangers the reproductive system and systemic metabolism of patients. We aimed to investigate the differences in metabolic profiles in the follicular fluid between infertile patients with endometriosis and controls. A total of 25 infertile patients with endometriosis and 25 infertile controls who were similar in age, BMI, fertilization method and ovulation induction treatment were recruited in this study. Metabolomics analysis of follicular fluid was performed by two methods of high-performance liquid chromatography tandem mass spectrometry. There were 36 upregulated and 17 downregulated metabolites in the follicular fluid of patients in the endometriosis group. KEGG pathway analysis revealed that these metabolites were enriched in phenylalanine, tyrosine and tryptophan biosynthesis, aminoacyl-tRNA biosynthesis, phenylalanine metabolism and pyrimidine metabolism pathways. A biomarker panel consisting of 20 metabolites was constructed by random forest, with an accuracy of 0.946 and an AUC of 0.988. This study characterizes differences in follicular fluid metabolites and associated pathway profiles in infertile patients with endometriosis. These findings can provide a better comprehensive understanding of the disease and a new direction for the study of oocyte quality, as well as potential metabolic markers for the prognosis of endometriosis.

Metabolomics and its applications in assisted reproductive technology

Metabolomics, an emerging omics technology developed in the post-gene age, is an important part of systems biology. It interprets the pathophysiological state of the subject by quantitatively describing the dynamic changes of metabolites through analytical methods, mainly mass spectrometry (MS) and nuclear magnetic resonance (NMR). Assisted reproductive technology (ART) is a method used to manipulate sperm, oocytes, and embryos to achieve conception. Recently, several studies have reported that metabolomics methods can be used to measure metabolites in ART samples; these metabolites can be used to evaluate the quality of gametes and embryos. This article reviews the progress of research on metabolomics and the application of this technology in the field of ART, thus providing a reference for research and development directions in the future.

A Pilot Study on Biochemical Profile of Follicular Fluid in Breast Cancer Patients

Breast cancer (BC) is the most common type of cancer among women in almost all countries worldwide and is one of the oncological pathologies for which is indicated fertility preservation, a type of procedure used to help keep a person's ability to have children. Follicular fluid (FF) is a major component of oocyte microenvironment, which is involved in oocyte growth, follicular maturation, and in communication between germ and somatic cells; furthermore, it accumulates all metabolites during oocytes growth. To obtain information about changes on fertility due to cancer, we aimed at investigating potential biomarkers to discriminate between FF samples obtained from 16 BC patients and 10 healthy women undergoing in vitro fertilization treatments. An NMR-based metabolomics approach was performed to investigate the FF metabolic profiles; ELISA and western blotting assays were used to investigate protein markers of oxidative and inflammatory stress, which are processes closely related to cancer. Our results seem to suggest that FFs of BC women display some significant metabolic alterations in comparison to healthy controls, and these variations are also related with tumor staging.

Microbiological composition of follicular fluid in patients undergoing IVF and its association with infertility

PROBLEM

In recent years, the incidence of female infertility has risen sharply, which is affected by many factors. It was recognized that female reproductive tract microbes play a role in the process of female conception. If the reproductive tract microbes could solve a certain proportion of infertility, it would certainly reduce the pain and economic burden of many patients. The objective of this study was to investigate the microbial community composition of follicular fluid in infertile patients and its potential impact on infertility.

METHOD OF STUDY

Follicular fluid from 49 primary infertility and 52 secondary infertility patients was collected by a negative pressure needle, and the microbiota was analyzed by 16S rDNA sequencing.

RESULTS

It was found that Lactobacillus, especially L. crispatus, might have a positive effect on female pregnancy. Considering the presence or absence of male factors and different body mass indices, L. iners might inhibit female pregnancy. However, L. iners seemed to play a positive role in egg maturation, while Gardnerella and Cutibacterium acnes might have a negative effect on female pregnancy.

CONCLUSIONS

This study suggested the potential role of Lactobacillus in follicular fluid in improving female infertility and provided a theoretical basis for the future microbiological treatment of female infertility.

The effect of growth hormone on the metabolome of follicular fluid in patients with diminished ovarian reserve

BACKGROUND

Increasing evidence supports that the co-treatment with growth hormone (GH) enhances ovarian response and oocyte quality during controlled ovarian stimulation (COS) in patients with diminished ovarian reserve (DOR). The composition of follicular fluid (FF) plays an essential role in oocyte development and mirrors the communication occurring between the oocyte and follicular microenvironment. However, the effect of GH on the FF metabolome remains unclear.

METHODS

This prospective observational study recruited DOR patients undergoing in vitro fertilization (IVF) cycles with minimal stimulation protocol for COS. Each patient receiving GH co-treatment was matched to a patient without GH co-treatment by propensity score matching. The FF was collected after isolating oocytes and assayed by gas chromatograph-mass spectrometry (GC-MS) metabolomics. The Pearson correlation was performed to evaluate the relationship between the number of oocytes retrieved and the levels of differential metabolites. The KEGG database was used to map differential metabolites onto various metabolic pathways.

RESULTS

One hundred thirty-four FF metabolites were identified by GC-MS metabolomics. Twenty-four metabolites, including glutathione, itaconic acid and S-adenosylmethionin (SAM) showed significant differences between the GH and control groups (p-value < 0.05 and q-value < 0.1). In addition, the number of oocytes retrieved was significantly higher in the GH group compared to the control group (3 vs 2, p = 0.04) and correlated with the levels of five differential metabolites. Among them, the levels of antioxidant metabolite itaconic acid were upregulated by GH administration, while SAM levels were downregulated.

CONCLUSIONS

The co-treatment with GH during COS may improve oocyte development by altering FF metabolite profiles in DOR patients. However, given the downregulation of SAM, a regulator of genomic imprinting, the potential risk of imprinting disturbances should not be neglected.

Seasonal variations in the metabolomic profile of the ovarian follicle components in Italian Mediterranean Buffaloes

The aim of this work was to evaluate the seasonal effect on the metabolomic profile of the ovarian follicle in Italian Mediterranean buffalo to unravel the causes of the reduced competence during the non-breeding season (NBS). Samples of follicular fluid, follicular cells, cumulus cells and oocytes were collected from abattoir-derived ovaries during breeding season (BS) and NBS and analyzed by 1H Nuclear Magnetic Resonance. The Orthogonal Projections to Latent Structures of the Discriminant Analysis showed clear separation into seasonal classes and Variable Importance in Projection method identified differentially abundant metabolites between seasons. Seasonal differences were recorded in metabolite content in all analyzed components suggesting that the decreased oocyte competence during NBS may be linked to alteration of several metabolic pathways. The pathway enrichment analysis revealed that differences in the metabolites between the seasons were linked to glutathione, energy generating and amino acid metabolism and phospholipid biosynthesis. The current work allows the identification of potential positive competence markers in the follicular fluid as glutathione, glutamate, lactate and choline, and negative markers like leucine, isoleucine and β-hydroxybutyrate. These results form a major basis to develop potential strategies to optimize the follicular environment and the IVM medium to improve the competence of oocytes during the NBS.

Follicular fluid biomarkers for prediction of human IVF outcome in women with poor ovarian response

Background

The aim of controlled ovarian stimulation is to achieve an optimal number of mature oocytes to obtain good-quality embryos. High follicular fluid (FF) concentrations of FSH, hCG, and LH promote oocyte maturation and are associated with a higher probability of fertilization. LH concentrations in FF are consistently higher in follicles that will lead to a successful IVF outcome. The levels of some of these FF biomarkers may vary among different ovarian stimulation schemes; however, the effects of corifollitropin alfa, recombinant FSH (rFSH), LH (rLH), and highly purified urinary menotropins uhMG on these biomarkers are still unknown. The objective of this study was to characterize the profile of FF biomarkers (leptin, vascular endothelial growth factor (VEGF), metalloproteinases (MMPs), and NO2−/NO3−) according to three different protocols of controlled ovarian stimulation (COS) in poor ovarian responders (POR) and to evaluate the association between these profiles and clinical outcomes. Three groups of POR patients were examined according to the protocols used.

Results

Group C showed significant higher levels in all biomarkers (p < 0001). FF samples from Group B had the lowest levels of VEGF and Pro-MMP-9. Group A showed the lowest concentration of pro-MMP-2. The VEGF level and number of captured oocytes were positively correlated in Group C (r = 0.534, p = 0.01). MMP-9 and fertilization rate were negatively correlated in Group C (r = −0.476, p = 0.02). We found negative correlations between proMMP-2 and serum estradiol levels on the day of rhCG administration.

Conclusion

We found significant variations in the biomarker concentrations between the different controlled ovarian stimulation schemes used in POR patients. These differences can be potentially explained by the nature and composition of the gonadotropins. Our results support the hypothesis that some of these molecules should be thoroughly investigated as noninvasive predictors of egg quality.

Cell-Free DNA as a New Biomarker of IVF Success, Independent of Any Infertility Factor, Including Endometriosis

Cell-free DNA fragments detected in blood and in other biological fluids are released from apoptotic/necrotic cells. In this study, we analyzed cfDNA levels in follicular fluid (FF) samples from patients with infertility. Samples were collected from 178 infertile women and cfDNA was extracted and quantified by qPCR, using ALU115 and ALU247 primers, and statistical correlations were performed. We found that cfDNA concentration was significantly higher in FF pools from women aged 35 and over than in women under 35 years of age (p = 0.017). We also found that q247 cfDNA levels were significantly higher in women with an associated female factor, such as endometriosis, PCOS and POF, compared with women with no specific cause of infertility (p = 0.033). The concentration of cfDNA did not vary significantly in each group of women with an associated female factor. The concentration of cfDNA was significantly higher in the FF of women that obtained embryos with a high fragmentation rate, compared to embryos with a low fragmentation rate (p = 0.007). Finally, we found that women who did not become pregnant during IVF treatments had higher q247 cfDNA levels (p = 0.043). The quantification of cfDNA could be an important biomarker of follicular micro-environment quality to predict embryo quality and the success of IVF, making them more specific and effective.

Implications of High-Density Cholesterol Metabolism for Oocyte Biology and Female Fertility

Cholesterol is an essential component of animal cells. Different regulatory mechanisms converge to maintain adequate levels of this lipid because both its deficiency and excess are unfavorable. Low cell cholesterol content promotes its synthesis and uptake from circulating lipoproteins. In contrast, its excess induces the efflux to high-density lipoproteins (HDL) and their transport to the liver for excretion, a process known as reverse cholesterol transport. Different studies suggest that an abnormal HDL metabolism hinders female fertility. HDL are the only lipoproteins detected in substantial amounts in follicular fluid (FF), and their size and composition correlate with embryo quality. Oocytes obtain cholesterol from cumulus cells via gap junctions because they cannot synthesize cholesterol de novo and lack HDL receptors. Recent evidence has supported the possibility that FF HDL play a major role in taking up excess unesterified cholesterol (UC) from the oocyte. Indeed, genetically modified mouse models with disruptions in reverse cholesterol transport, some of which show excessive circulating UC levels, exhibit female infertility. Cholesterol accumulation can affect the egg´s viability, as reported in other cell types, and activate the plasma membrane structure and activity of membrane proteins. Indeed, in mice deficient for the HDL receptor Scavenger Class B Type I (SR-B1), excess circulating HDL cholesterol and UC accumulation in oocytes impairs meiosis arrest and hinders the developmental capacity of the egg. In other cells, the addition of cholesterol activates calcium channels and dysregulates cell death/survival signaling pathways, suggesting that these mechanisms may link altered HDL cholesterol metabolism and infertility. Although cholesterol, and lipids in general, are usually not evaluated in infertile patients, one study reported high circulating UC levels in women showing longer time to pregnancy as an outcome of fertility. Based on the evidence described above, we propose the existence of a well-regulated and largely unexplored system of cholesterol homeostasis controlling traffic between FF HDL and oocytes, with significant implications for female fertility.

Follicular Fluid: A Powerful Tool for the Understanding and Diagnosis of Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) represents one of the leading causes of anovulatory infertility and affects 5% to 20% of women worldwide. Until today, both the subsequent etiology and pathophysiology of PCOS remain unclear, and patients with PCOS that undergo assisted reproductive techniques (ART) might present a poor to exaggerated response, low oocyte quality, ovarian hyperstimulation syndrome, as well as changes in the follicular fluid metabolites pattern. These abnormalities originate a decrease of Metaphase II (MII) oocytes and decreased rates for fertilization, cleavage, implantation, blastocyst conversion, poor egg to follicle ratio, and increased miscarriages. Focus on obtaining high-quality embryos has been taken into more consideration over the years. Nowadays, the use of metabolomic analysis in the quantification of proteins and peptides in biological matrices might predict, with more accuracy, the success in assisted reproductive technology. In this article, we review the use of human follicular fluid as the matrix in metabolomic analysis for diagnostic and ART predictor of success for PCOS patients.

Identification of the Metabolomics Signature of Human Follicular Fluid from PCOS Women with Insulin Resistance

Context. Polycystic ovary syndrome (PCOS) is a gynecological endocrine disease, and approximately 60% of patients with PCOS have different degrees of insulin resistance (IR). The regulatory role of metabolic networks in human follicular fluid (FF) related to IR in PCOS remains unclear. Aims. To explore the effect of IR on the metabolism of PCOS by analyzing the changes in FF metabolites in PCOS patients who are undergoing assisted reproductive technology based on the metabonomic platform of ultraperformance gas chromatography coupled to mass spectrometry (GC/MS). Method. Eight PCOS patients with IR (PCOS-IR) and 8 PCOS patients without IR (PCOS-NIR) were enrolled. All patients received controlled ovarian stimulation by using the gonadotropin-releasing hormone (GnRH) antagonist protocol, and the FF of a single dominant follicle was collected on the day of oocyte retrieval. The metabolite profiles of the FF were determined by GC/MS. Key Results. A total of 20 differentially expressed metabolites in FF were identified. Compared with levels in the PCOS-NIR group, stearic acid, palmitic acid, pentadecanoic acid, stigmasterol, citric acid, isocitric acid, thymine, and pyruvic acid in FF were significantly increased in the PCOS-IR group. Lithocholic acid and sinapinic acid in FF decreased significantly. The affected metabolic pathways with potential regulatory roles were identified by KEGG annotation. Conclusion. Compared with the PCOS-NIR group, the PCOS-IR group showed more significant metabolic abnormalities. Implications. These results will help us to understand the pathogenesis of PCOS combined with IR and will provide new clues for studying metabolic disorders associated with PCOS, e.g., IR.

Are the Follicular Fluid Characteristics of Recovered Coronavirus Disease 2019 Patients Different From Those of Vaccinated Women Approaching in vitro Fertilization?

The aim of this pilot study is to evaluate if SARS-CoV-2 infection or vaccination against SARS-CoV-2 infection induce observable metabolic effects in follicular fluid of women who are following in vitro fertilization (IVF) treatments. The possible impact of coronavirus disease 2019 (COVID-19) on fertility and IVF outcome is considered. We have selected for this study: six women vaccinated against SARS-CoV-2 infection, five recovered COVID-19 patients, and we used nine healthy women as the control group. At the time of oocytes retrieval from participants in the study, follicular fluids were collected and metabolomic analysis was performed by ¹H NMR spectroscopy in combination with multivariate analysis to interpret the spectral data. The search for antibody positivity in the follicular fluid aspirates was also carried out, together with the western blotting analysis of some inflammatory proteins, interleukin-6, tumor necrosis factor α (TNFα), and the free radical scavenger superoxide dismutase 2. Higher levels of Ala and Pro together with lower levels of lipids and trimethylamine N-oxide (TMAO) were found in follicular fluids (FFs) of vaccinated women while lower levels of many metabolites were detected in FFs of recovered COVID patients. Expression level of TNF-α was significantly lower both in recovered COVID-19 patients and vaccinated women in comparison to healthy controls.

Expression of pro-apoptotic and anti-apoptotic proteins in granulosa cells of women with diminished ovarian reserve

PURPOSE

To evaluate the expressions of caspase-3 and cytochrome c and heat shock protein 70 (Hsp70) in granulosa cells (GCs) from women with normal ovarian reserve (NOR) and diminished ovarian reserve (DOR) undergoing intracytoplasmic sperm injection (ICSI).

METHODS

GCs were collected from 117 infertile women during oocyte retrieval. Patients were classified into four groups as follows: DOR-COC score of 0, DOR-COC score of I, NOR-COC score of 0, and NOR-COC score of I. The caspase-3, cytochrome c, and Hsp70 analyses were performed immunohistochemically in GCs. The ICSI outcomes were evaluated prospectively.

RESULTS

The clinical pregnancy and live birth rates were higher in DOR-COC score of I (15, 30.6%; 14, 38.9%) and NOR-COC score of I (19, 38.77%; 19, 52.7%) groups, compared with DOR-COC score of 0 (12, 24.4%; 3, 6.1%) and NOR-COC score of 0 (3, 6.1%; 0%) groups (p = 0.0001; 0.00002), respectively. Caspase-3 and cytochrome c expression levels were higher in DOR-COC score of 0 (23, 65.7%; 25, 71.4%) and NOR-COC score of 0 groups (19, 61.3%; 20, 64.5%), compared with DOR-COC score of I (8, 32%; 9, 36%) and NOR-COC score of I groups (7, 26.9%; 8, 30.8%) (p = 0.00297; p = 0.002), respectively. Lower expression levels of Hsp70 were found in DOR-COC score of 0 (11, 31.4%) and NOR-COC score of 0 groups (10, 32.3%), compared with DOR-COC score of I (16, 64%) and NOR-COC score of I groups (20, 76.9%) (p = 0.001), respectively. Hsp70 expression levels were positively correlated with the number of day 3 good-quality embryo and negatively correlated with estradiol levels in the DOR group.

CONCLUSION

Our data suggest that COC score of 0 is associated with increased expression levels of apoptotic proteins, decreased expression levels of anti-apoptotic protein, and poor ICSI clinical outcomes in women with and without DOR.

Age-Dependent Metabolomic Profile of the Follicular Fluids From Women Undergoing Assisted Reproductive Technology Treatment

Female fertility declines with age, and this natural variation culminates in reproductive senescence. Human follicular fluids are rich in low-molecular weight metabolites which are responsible for the maturation of oocytes. The metabolomic approaches are powerful tools to study biochemical markers of oocyte quality in the follicular fluids. It is necessary to identify and quantify the reliable metabolites in follicular fluids reflecting oocyte developmental potential. The goal of this study is to conduct a metabolomic analysis of the follicular fluids in women of different ages and study the metabolomic profile of the follicular fluids in relationship with oocyte quality in assisted reproductive technology (ART) treatment. A total of 30 women seeking for ART treatment at the Women's Hospital, Zhejiang University School of Medicine from October 2014 to April 2015 were recruited for the present study. Fifteen women aged from 39 to 47 were grouped as advanced maternal age, and the other 15 women aged from 27 to 34, as young controls. Ovarian stimulation and oocyte retrieval were conducted using a regular protocol involving mid-luteal pituitary down-regulation and controlled ovarian stimulation. Follicular fluids from mature follicles were collected and centrifuged for analyses. Liquid Chromatography-Mass Spectrometry (LC-MS) and Gas Chromatography-Mass Spectroscopy (GC-MS) were used to perform the quantitative metabolomic analysis. The follicular fluid levels of 311 metabolites and the metabolic significance were assessed. 70 metabolites showed significant differences between women with young and advanced ages. Follicular fluids from women with advanced age showed significantly higher levels of creatine, histidine, methionine, trans-4-hydroxyproline, choline, mevalonate, N2,N2-dimethylguanosine and gamma-glutamylvaline, as compared to those from the young age group. 8 metabolites were found significantly correlated with maternal age positively. Moreover, 3 metabolites were correlated with the number of oocytes retrieved, and 5 metabolites were correlated with cleaved embryo numbers, both negatively. The follicular fluids from women undergoing ART treatment exhibited age-dependent metabolomic profile. Metabolites associated with oocyte quality were identified, suggesting them as potential biomarkers for oocyte maturation and ART outcomes.

Cumulus cell acetyl-CoA metabolism from acetate is associated with maternal age but only partially with oocyte maturity

Cumulus cell (CC) clumps that associate with oocytes provide the oocytes with growth and signaling factors. Thus, the metabolism of the CCs may influence oocyte function, and CC metabolism may be predictive of oocyte competence for in vitro fertilization. CCs are thought to be highly glycolytic, but data on the use of other potential carbon substrates are lacking in humans. This prospective and blinded cohort study was designed to examine the substrate utilization of CCs by age and oocyte competence. Individual sets of CC clumps from participants were removed after oocyte retrieval procedure then, incubated with stable isotope labeled substrates, and analyzed using liquid chromatography-high resolution mass spectrometry (LC-HRMS) for isotopologue enrichment of major metabolic intermediates, including acetyl-CoA. The acyl-chain of acetyl-CoA contains 2 carbons that can be derived from ¹³C-labeled substrates resulting in an M + 2 isotopologue that contains 2 ¹³C atoms. Comparing the fate of three major carbon sources, mean enrichment of M + 2 acetyl-CoA (mean, standard deviation) was for glucose (3.6, 7.7), for glutamine (9.4, 6.2), and for acetate (20.7, 13.9). Due to this unexpected high and variable labeling from acetate, we then examined acetyl-CoA mean % enrichment from acetate in 278 CCs from 21 women ≤34 (49.06, 12.73) decreased with age compared to 124 CCs from 10 women >34 (43.48, 16.20) (p = 0.0004, t-test). The CCs associated with the immature prophase I oocytes had significantly lower enrichment in M + 2 acetyl CoA compared to the CCs associated with the metaphase I and metaphase II oocytes (difference: -6.02, CI: -1.74,-13.79, p = 0.013). Acetate metabolism in individual CC clumps was positively correlated with oocyte maturity and decreased with maternal age. These findings indicate that CC metabolism of non-glucose substrates should be investigated relative to oocyte function and age-related fertility.Abbreviations: CCs: cumulus cells; COC: cumulus-oocyte complex; LC-MS: liquid chromatography-mass spectrometry; acetyl-CoA: acetyl-Coenzyme A; CoA: Coenzyme A.

Non invasive assessment of human oocytes and embryos in assisted reproduction: Review on present practices and future trends

Oocyte and embryo grading is one of the most important steps in assisted reproductive technology to identify the best among cultured embryos for transfer or vitrification. The most commonly used non-invasive method is morphological assessment of gametes and embryos using a microscope. This method despite being simple and cost-effective has interobserver and intraobserver variability and subjectivity and has little to offer about the physiological state of embryos. This review sourced research articles and reviews pertaining to other non-invasive assessment methodologies from Medline and PubMed to collate latest technologies in vogue and identify novel methodologies of the future. The review assesses the current understanding in oocyte and embryo grading and touches upon novel non-invasive techniques and potential biomarkers to identify the best embryo. The latest available literature on time-lapse imaging, hierarchical algorithms, omics (consisting of proteomics and secretomes), miRNAs, mitochondrial RNAs and artificial intelligence has been accessed to summarize the enormous information available, to identify gaps in current interpretations, to identify emerging technologies and to provide direction for future research. This review will greatly benefit anyone practicing assisted reproduction and clinical embryology.

Effects of melatonin and human follicular fluid supplementation of in vitro maturation medium on mouse vitrified germinal vesicle oocytes: A laboratory study

Background

Vitrification as the most efficient method of cryopreservation, enables successful storage of oocytes for couples who undergo specific procedures including surgery and chemotherapy. However, the efficacy of in vitro maturation (IVM) methods with vitrified germinal vesicle (GV) oocytes could be improved.

Objective

As melatonin and follicular fluid (FF) might enhance IVM conditions, we used these supplements to assess the maturation rate of vitrified GV oocytes and their artificial fertilization rate.

Materials and Methods

Four hundred mouse GV oocytes were harvested, vitrified, and assigned into control (C-Vit-GV) and treatment groups of melatonin (M-Vit-GV), human follicular fluid (HFF-Vit-GV), and a combination (M + HFF-Vit-GV). A non-vitrified group of GV oocytes (non-Vit-GV) and a group of in vivo matured metaphase II (Vivo-MII) oocytes served as control groups to evaluate the vitrification and IVM conditions, respectively. Maturation of GV oocytes to MII and further development to two-cell-stage embryos were determined in the different groups.

Results

Development to two-cell embryos was comparable between the Vivo-MII and non-Vit-GV groups. IVM and in vitro fertilization (IVF) results in the non-Vit-GV group were also comparable with the C-Vit-GV oocytes. In addition, the IVM and IVF outcomes were similar across the different treatment groups including the M-Vit-GV, HFF-Vit-GV, M + HFF-Vit-GV, and C-Vit-GV oocytes.

Conclusion

Employing an appropriate technique of vitrification followed by suitable IVM conditions can lead to reasonable IVF outcomes which may not benefit from extra supplementations. However, whether utilizing other supplementation formulas could improve the outcome requires further investigation.

The Mechanism of Traditional Chinese Medicine Based on Semi-Targeted Metabolomics to Improve IVF Outcomes in Senile Patients

Objective

To identify the biological function and metabolic pathway of differential metabolites in follicular fluid of senile patients with kidney qi deficiency undergoing in vitro fertilization-embryo transfer (IVF-ET) and observe the effect of kidney-invigorating herbs on IVF outcomes in senile patients.

Methods

A total of 95 women undergoing IVF treatment were recruited and divided into three groups, including 34 cases in the treatment group (the senile patients with kidney qi deficiency after the intervention of Chinese medicine), 31 cases in the experiment group (the senile patients with kidney qi deficiency of no intervention of Chinese medicine), and 30 cases in the control group (young women with infertility due to male factor). The three groups of women were treated with long protocol ovarian hyperstimulation; the treatment group was given Qi-Zi-Yu-Si decoction on the day of HCG downregulation. Their IVF clinical outcomes were observed. The metabolites changes of kidney qi deficiency syndrome were analyzed in follicular fluid metabolomics using liquid chromatography-mass spectrometry (UPLC-MS/MS).

Results

The syndrome score of kidney qi deficiency syndrome in the treatment group was significantly improved after treatment (P < 0.01). Compared with the experiment group, the available embryo rate and implantation rate were increased, and the difference was statistically significant (P < 0.05). Progesterone, indoleacrylic acid, 2-propenyl 1-(1-propenylsulfinyl) propyl disulfide, N-acetyltryptophan, decanoylcarnitine, 20a-dihydroprogesterone, testosterone acetate, eicosatrienoic acid, 1H-indole-3-carboxaldehyde, choline, phosphorylcholine, and tryptophan were downregulated in the treatment group. Through pathway analysis, glycerophospholipid metabolism and steroid hormone biosynthesis were regulated in senile patients with kidney qi deficiency after Qi-Zi-Yu-Si decoction intervention.

Conclusion

Qi-Zi-Yu-Si decoction can effectively improve the IVF outcome and clinical symptoms of senile patients. Follicular fluid metabolites were significantly changed in senile infertile women with kidney qi deficiency, and the mechanism by which kidney-invigorating herbs improve IVF treatment outcomes may be related to glycerophospholipid metabolism and steroid hormone biosynthesis. This study was registered in the Chinese Clinical Trials Registry Platform (ChiCTR1800014422).

Altered Follicular Fluid Metabolic Pattern Correlates with Female Infertility and Outcome Measures of In Vitro Fertilization

Nearly 40-50% of infertility problems are estimated to be of female origin. Previous studies dedicated to the analysis of metabolites in follicular fluid (FF) produced contrasting results, although some valuable indexes capable to discriminate control groups (CTRL) from infertile females (IF) and correlate with outcome measures of assisted reproduction techniques were in some instances found. In this study, we analyzed in blind FF of 35 control subjects (CTRL = patients in which inability to obtain pregnancy was exclusively due to a male factor) and 145 IF (affected by: endometriosis, n = 19; polycystic ovary syndrome, n = 14; age-related reduced ovarian reserve, n = 58; reduced ovarian reserve, n = 29; unexplained infertility, n = 14; genetic infertility, n = 11) to determine concentrations of 55 water- and fat-soluble low molecular weight compounds (antioxidants, oxidative/nitrosative stress-related compounds, purines, pyrimidines, energy-related metabolites, and amino acids). Results evidenced that 27/55 of them had significantly different values in IF with respect to those measured in CTRL. The metabolic pattern of these potential biomarkers of infertility was cumulated (in both CTRL and IF) into a Biomarker Score index (incorporating the metabolic anomalies of FF), that fully discriminated CTRL (mean Biomarker Score value = 4.00 ± 2.30) from IF (mean Biomarker Score value = 14.88 ± 3.09, p < 0.001). The Biomarker Score values were significantly higher than those of CTRL in each of the six subgroups of IF. Posterior probability curves and ROC curve indicated that values of the Biomarker Score clustered CTRL and IF into two distinct groups, based on the individual FF metabolic profile. Furthermore, Biomarker Score values correlated with outcome measures of ovarian stimulation, in vitro fertilization, number and quality of blastocysts, clinical pregnancy, and healthy offspring. These results strongly suggest that the biochemical quality of FF deeply influences not only the effectiveness of IVF procedures but also the following embryonic development up to healthy newborns. The targeted metabolomic analysis of FF (using empowered Redox Energy Test) and the subsequent calculation of the Biomarker Score evidenced a set of 27 low molecular weight infertility biomarkers potentially useful in the laboratory managing of female infertility and to predict the success of assisted reproduction techniques.

Lipid profile of extracellular vesicles and their relationship with bovine oocyte developmental competence: New players in intra follicular cell communication

Cell communication within the ovarian follicle is crucial during folliculogenesis to assure an ideal environment for the oocyte to achieve full developmental competence. Intercellular communication is facilitated by the presence of follicular fluid, which mediates the transfer of signaling molecules. Recently, extracellular vesicles (exosomes and microvesicles) containing mRNAs, miRNAs and proteins were described in mammalian follicular fluid. Besides these molecules, extracellular vesicles (EVs) can mediate the transfer of lipids that can act as signal transducers activating second messengers and modulating intracellular pathways. Our goal was to determine the lipid profile of exosomes (small extracellular vesicles) and microvesicles (large extracellular vesicles) from bovine ovarian follicles containing oocytes with different developmental capabilities to verify potential relationships to competence. Using mass spectrometry, we examined the lipid content of EVs present in the follicular fluid of follicles enclosing oocytes that were either unable to cleave (NCLEAVE), arrested at cleavage stage (CLEAVE), or developed to the blastocyst stage (BLAST) after parthenogenetic activation. Although most of the 514 lipids identified in the follicular fluid EVs were common among all groups, 10 exosome-derived lipids and 15 microvesicle-derived lipids were present exclusively in the BLAST group, suggesting a potential relationship with developmental competence. Therefore, our data indicate that the EVs present in follicular fluid of antral follicles of similar morphology contain lipids that may be used as biomarkers associated with the developmental capability of the oocyte to develop to the blastocyst stage.

Ovarian cholesterol efflux: ATP-binding cassette transporters and follicular fluid HDL regulate cholesterol content in mouse oocytes†

High density lipoproteins (HDL) take up cholesterol from peripheral tissues via ABC transporters and deliver it to the liver via scavenger receptor class B type I (SR-B1). HDL are the main lipoproteins present in follicular fluid (FF). They are thought to derive from plasma, but their origin is still controversial. SR-B1 knock-out (KO) mice have provided important evidence linking HDL metabolism and female fertility. These mice have cholesterol-rich circulating HDL and female infertility that can be restored by treating mice with the cholesterol-lowering drug probucol. Ovulated oocytes from SR-B1 KO females are dysfunctional and show excess cholesterol. The mechanisms explaining the contribution of FF HDL to oocyte cholesterol homeostasis are unknown. Here, using quantitation of filipin fluorescence we show that in SR-B1 KO ovaries, cholesterol excess is first observed in immature oocytes in antral follicles. By performing cross-transplant experiments between WT and apolipoprotein A-I deficient (ApoA-I KO) mice, which lack the main protein component of HDL, we provide evidence supporting the plasmatic origin of FF HDL. Also, we demonstrate that probucol treatment in SR-B1 KO females results in lowering of cholesterol content in their oocytes. Incubation of oocytes from SR-B1 KO mice with purified WT HDL reduces their cholesterol content, suggesting that HDL promote efflux of excess cholesterol from oocytes. In agreement with this hypothesis, we identified ABC transporters in oocytes and observed that ABCA1 KO oocytes have excess cholesterol and lower viability than WT oocytes.

Ovarian stimulation drugs alter the metabolite content of the growing follicle: in vivo spectroscopic evaluation of follicle fluid

Objective

To determine and compare metabolite content using magnetic resonance spectroscopy (MRS) of growing follicles in patients with polycystic ovary syndrome (PCOS) receiving recombinant follicle stimulating hormone (rFSH), clomiphene citrate (CC) or aromatase inhibitor (AI) for ovarian stimulation.

Material and Methods

Thirty patients diagnosed with PCOS and infertility and scheduled for ovarian stimulation were divided by therapy, rFSH/CC/AI, into three equal groups. Five fertile cases were designated as the control group. When the follicle diameters reached 16-18 mm in each group, patients underwent MRS and the metabolite content of a dominant follicle was analyzed. N-acetylaspartate, lactate (Lac), creatine (Cr), and choline (Cho) metabolite levels in parts per million were measured in the spectra.

Results

A ~three-fold decrease in dominant follicle Cho content was found in patients receiving CC compared to control subjects. Similarly, the dominant follicle Cho intensities of patients given rFSH and AI were noted to be significantly higher than those who received CC. Only dominant follicle Lac levels of the patients who received CC were found to be significantly higher than the other groups. Cr peak intensities of patients receiving CC were found to be approximately three times less than control subjects. Cr signal intensity was significantly higher in patients receiving rFSH or AI than in patients receiving CC. While two patients became pregnant in the CC group, three patients in the AI group and five patients in the rFSH group became pregnant. The main metabolites detected in patients who conceived in each group were Cho and Cr. In cases who could not conceive, while Lac and lipid signals increased, Cho and Cr signals decreased.

Conclusion

Unlike CC, ovarian stimulation with rFSH or AI does not alter dominant follicle metabolite content. The developmental capacity of a growing egg may be determined non-invasively with MRS.

Trimethylamine-N-oxide is present in human follicular fluid and is a negative predictor of embryo quality

STUDY QUESTION

Are levels of trimethylamine-N-oxide (TMAO) in human follicular fluid (FF) related to IVF outcomes?

SUMMARY ANSWER

Higher levels of TMAO are a negative predictor of oocyte fertilization and embryo quality.

WHAT IS KNOWN ALREADY

TMAO is a metabolic product of dietary choline and l-carnitine produced via subsequent enzymatic modifications by the intestinal microbiota and hepatocytes. TMAO promotes inflammatory and oxidative stress pathways and has been characterized as a causative biomarker for the development of cardiometabolic disease.

STUDY DESIGN, SIZE, DURATION

For the present cross-sectional study, samples (FF and plasma) from 431 modified natural cycle (MNC)-IVF cycles of 132 patients were collected prospectively between October 2014 and March 2018 in a single academic medical center.

PARTICIPANTS/MATERIALS, SETTING, METHODS

TMAO and its precursors (choline, l-carnitine and gamma-butyrobetaine) were measured by ultra-high-performance liquid chromatography/mass spectrometry in (i) matched FF and plasma from 63 MNC-IVF cycles, in order to compare metabolite levels in the two matrices and (ii) FF from 232 MNC-IVF cycles in which only one oocyte was retrieved at follicular puncture. The association between metabolite levels and oocyte fertilization, embryo fragmentation percentage, embryo quality and the occurrence of pregnancy was analyzed using multilevel generalized estimating equations with adjustment for patient and cycle characteristics.

MAIN RESULTS AND THE ROLE OF CHANCE

The level of choline was higher in FF as compared to matched plasma (P < 0.001). Conversely, the levels of TMAO and gamma-butyrobetaine were lower in FF as compared to plasma (P = 0.001 and P = 0.075, respectively). For all metabolites, there was a positive correlation between FF and plasma levels. Finally, levels of TMAO and its gut-derived precursor gamma-butyrobetaine were lower in FF from oocytes that underwent normal fertilization (TMAO: odds ratio [OR] 0.66 [0.49–0.90], P = 0.008 per 1.0-μmol/L increase; gamma-butyrobetaine: OR 0.77 [0.60–1.00], P = 0.047 per 0.1-μmol/L increase) and developed into top-quality embryos (TMAO: OR 0.56 [0.42–0.76], P < 0.001 per 1.0-μmol/L increase; gamma-butyrobetaine: OR 0.79 [0.62–1.00], P = 0.050 per 0.1-μmol/L increase) than in FF from oocytes of suboptimal development.

LIMITATIONS, REASONS FOR CAUTION

The individual contributions of diet, gut bacteria and liver to the metabolite pools have not been quantified in this analysis.

WIDER IMPLICATIONS OF THE FINDINGS

More research on the contribution of diet and the effect of gut bacteria on FF TMAO is warranted. Since TMAO integrates diet, microbiota and genetic setup of the person, our results indicate potential important clinical implications for its use as biomarker for lifestyle interventions to improve fertility.

STUDY FUNDING/COMPETING INTEREST(S)

No external funding was received for this project. The Department of Obstetrics and Gynecology of the University Medical Center Groningen received an unrestricted educational grant of Ferring Pharmaceutical BV, the Netherlands. The authors have no other conflicts of interest.

TRIAL REGISTRATION NUMBER

Netherlands Trial Register number NTR4409.

Omics and Artificial Intelligence to Improve In Vitro Fertilization (IVF) Success: A Proposed Protocol

The prediction of in vitro fertilization (IVF) outcome is an imperative achievement in assisted reproduction, substantially aiding infertile couples, health systems and communities. To date, the assessment of infertile couples depends on medical/reproductive history, biochemical indications and investigations of the reproductive tract, along with data obtained from previous IVF cycles, if any. Our project aims to develop a novel tool, integrating omics and artificial intelligence, to propose optimal treatment options and enhance treatment success rates. For this purpose, we will proceed with the following: (1) recording subfertile couples’ lifestyle and demographic parameters and previous IVF cycle characteristics; (2) measurement and evaluation of metabolomics, transcriptomics and biomarkers, and deep machine learning assessment of the oocyte, sperm and embryo; (3) creation of artificial neural network models to increase objectivity and accuracy in comparison to traditional techniques for the improvement of the success rates of IVF cycles following an IVF failure. Therefore, “omics” data are a valuable parameter for embryo selection optimization and promoting personalized IVF treatment. “Omics” combined with predictive models will substantially promote health management individualization; contribute to the successful treatment of infertile couples, particularly those with unexplained infertility or repeated implantation failures; and reduce multiple gestation rates.

Identifying biomarkers for predicting successful embryo implantation: applying single to multi-OMICs to improve reproductive outcomes

BACKGROUND

Successful embryo implantation is a complex process that requires the coordination of a series of events, involving both the embryo and the maternal endometrium. Key to this process is the intricate cascade of molecular mechanisms regulated by endocrine, paracrine and autocrine modulators of embryonic and maternal origin. Despite significant progress in ART, implantation failure still affects numerous infertile couples worldwide and fewer than 10% of embryos successfully implant. Improved selection of both the viable embryos and the optimal endometrial phenotype for transfer remains crucial to enhancing implantation chances. However, both classical morphological embryo selection and new strategies incorporated into clinical practice, such as embryonic genetic analysis, morphokinetics or ultrasound endometrial dating, remain insufficient to predict successful implantation. Additionally, no techniques are widely applied to analyse molecular signals involved in the embryo-uterine interaction. More reliable biological markers to predict embryo and uterine reproductive competence are needed to improve pregnancy outcomes. Recent years have seen a trend towards 'omics' methods, which enable the assessment of complete endometrial and embryonic molecular profiles during implantation. Omics have advanced our knowledge of the implantation process, identifying potential but rarely implemented biomarkers of successful implantation.

OBJECTIVE AND RATIONALE

Differences between the findings of published omics studies, and perhaps because embryonic and endometrial molecular signatures were often not investigated jointly, have prevented firm conclusions being reached. A timely review summarizing omics studies on the molecular determinants of human implantation in both the embryo and the endometrium will help facilitate integrative and reliable omics approaches to enhance ART outcomes.

SEARCH METHODS

In order to provide a comprehensive review of the literature published up to September 2019, Medline databases were searched using keywords pertaining to omics, including 'transcriptome', 'proteome', 'secretome', 'metabolome' and 'expression profiles', combined with terms related to implantation, such as 'endometrial receptivity', 'embryo viability' and 'embryo implantation'. No language restrictions were imposed. References from articles were also used for additional literature.

OUTCOMES

Here we provide a complete summary of the major achievements in human implantation research supplied by omics approaches, highlighting their potential to improve reproductive outcomes while fully elucidating the implantation mechanism. The review highlights the existence of discrepancies among the postulated biomarkers from studies on embryo viability or endometrial receptivity, even using the same omic analysis.

WIDER IMPLICATIONS

Despite the huge amount of biomarker information provided by omics, we still do not have enough evidence to link data from all omics with an implantation outcome. However, in the foreseeable future, application of minimally or non-invasive omics tools, together with a more integrative interpretation of uniformly collected data, will help to overcome the difficulties for clinical implementation of omics tools. Omics assays of the embryo and endometrium are being proposed or already being used as diagnostic tools for personalised single-embryo transfer in the most favourable endometrial environment, avoiding the risk of multiple pregnancies and ensuring better pregnancy rates.

The utility of nuclear magnetic resonance spectroscopy in assisted reproduction

Infertility affects approximately 15-20% of individuals of reproductive age worldwide. Over the last 40 years, assisted reproductive technology (ART) has helped millions of childless couples. However, ART is limited by a low success rate and risk of multiple gestations. Devising methods for selecting the best gamete or embryo that increases the ART success rate and prevention of multiple gestation has become one of the key goals in ART today. Special emphasis has been placed on the development of non-invasive approaches, which do not require perturbing the embryonic cells, as the current morphology-based embryo selection approach has shortcomings in predicting the implantation potential of embryos. An observed association between embryo metabolism and viability has prompted researchers to develop metabolomics-based biomarkers. Nuclear magnetic resonance (NMR) spectroscopy provides a non-invasive approach for the metabolic profiling of tissues, gametes and embryos, with the key advantage of having a minimal sample preparation procedure. Using NMR spectroscopy, biologically important molecules can be identified and quantified in intact cells, extracts or secretomes. This, in turn, helps to map out the active metabolic pathways in a system. The present review covers the contribution of NMR spectroscopy in assisted reproduction at various stages of the process.

Metabolic co-dependence of the oocyte and cumulus cells: essential role in determining oocyte developmental competence

BACKGROUND

Within the antral follicle, the oocyte is reliant on metabolic support from its surrounding somatic cells. Metabolism plays a critical role in oocyte developmental competence (oocyte quality). In the last decade, there has been significant progress in understanding the metabolism of the cumulus-oocyte complex (COC) during its final stages of growth and maturation in the follicle. Certain metabolic conditions (e.g. obesity) or ART (e.g. IVM) perturb COC metabolism, providing insights into metabolic regulation of oocyte quality.

OBJECTIVE AND RATIONALE

This review provides an update on the progress made in our understanding of COC metabolism, and the metabolic conditions that influence both meiotic and developmental competence of the oocyte.

SEARCH METHODS

The PubMed database was used to search for peer-reviewed original and review articles. Searches were performed adopting the main terms 'oocyte metabolism', 'cumulus cell metabolism', 'oocyte maturation', 'oocyte mitochondria', 'oocyte metabolism', 'oocyte developmental competence' and 'oocyte IVM'.

OUTCOMES

Metabolism is a major determinant of oocyte quality. Glucose is an essential requirement for both meiotic and cytoplasmic maturation of the COC. Glucose is the driver of cumulus cell metabolism and is essential for energy production, extracellular matrix formation and supply of pyruvate to the oocyte for ATP production. Mitochondria are the primary source of ATP production within the oocyte. Recent advances in real-time live cell imaging reveal dynamic fluctuations in ATP demand throughout oocyte maturation. Cumulus cells have been shown to play a central role in maintaining adequate oocyte ATP levels by providing metabolic support through gap junctional communication. New insights have highlighted the importance of oocyte lipid metabolism for oocyte oxidative phosphorylation for ATP production, meiotic progression and developmental competence. Within the last decade, several new strategies for improving the developmental competence of oocytes undergoing IVM have emerged, including modulation of cyclic nucleotides, the addition of precursors for the antioxidant glutathione or endogenous maturation mediators such as epidermal growth factor-like peptides and growth differentiation factor 9/bone morphogenetic protein 15. These IVM additives positively alter COC metabolic endpoints commonly associated with oocyte competence. There remain significant challenges in the study of COC metabolism. Owing to the paucity in non-invasive or in situ techniques to assess metabolism, most work to date has used in vitro or ex vivo models. Additionally, the difficulty of measuring oocyte and cumulus cell metabolism separately while still in a complex has led to the frequent use of denuded oocytes, the results from which should be interpreted with caution since the oocyte and cumulus cell compartments are metabolically interdependent, and oocytes do not naturally exist in a naked state until after fertilization. There are emerging tools, including live fluorescence imaging and photonics probes, which may provide ways to measure the dynamic nature of metabolism in a single oocyte, potentially while in situ.

WIDER IMPLICATIONS

There is an association between oocyte metabolism and oocyte developmental competence. Advancing our understanding of basic cellular and biochemical mechanisms regulating oocyte metabolism may identify new avenues to augment oocyte quality and assess developmental potential in assisted reproduction.

The follicular fluid metabolome differs according to the endometriosis phenotype

RESEARCH QUESTION

Is there a follicular fluid-specific metabolic profile in deep infiltrating endometriosis (DIE) depending on the presence of an associated ovarian endometrioma (OMA) that could lead to the identification of biomarkers for diagnosis and prognosis of the disease?

DESIGN

In this prospective cohort study, proton nuclear magnetic resonance (¹H-NMR) experiments were carried out on 50 follicular fluid samples from patients presenting with DIE, associated or not associated with an OMA, and 29 follicular fluid samples from patients with infertility caused by a tubal obstruction.

RESULTS

Concentrations of glucose, citrate, creatine and amino acids such as tyrosine and alanine were lower in women with DIE than control participants, whereas concentrations of lactate, pyruvate, lipids and ketone bodies were higher. Metabolic analysis revealed enhanced concentrations of glycerol and ketone bodies in patients with OMA, indicative of an activation of lipolysis followed by beta-oxidation. Concentrations of lactate and pyruvate were increased in patients without OMA, whereas the concentration of glucose was decreased, highlighting activation of the anaerobic glycolysis pathway. Differences in concentrations of amino acids such as threonine and glutamine were also statistically relevant in discriminating between the presence or absence of OMA.

CONCLUSIONS

Results indicate a mitochondrial dysregulation in endometriosis phenotypes, with a modified balance between anaerobic glycolysis and beta-oxidation in OMA phenotypes that could affect the fertility of women with endometriosis. As the composition of the follicular fluid has been shown to be correlated with oocyte development and outcome of implantation after fertilization, these findings may help explain the high level of infertility in these patients.

A Shift in Glycerolipid Metabolism Defines the Follicular Fluid of IVF Patients with Unexplained Infertility

Follicular fluid (FF) constitutes the microenvironment of the developing oocyte. We recently characterized its lipid composition and found lipid signatures of positive pregnancy outcome after in vitro fertilization (IVF). In the current study, we aimed to test the hypothesis that unexplained female infertility is related to lipid metabolism, given the lipid signature of positive-outcome IVF patients we previously found. Assuming that FF samples from IVF patients with male factor infertility can represent a non-hindered metabolic microenvironment, we compared them to FF taken from women with unexplained infertility. FF from patients undergoing IVF was examined for its lipid composition. We found highly increased triacylglycerol levels, with a lower abundance of monoacylglycerols, phospholipids and sphingolipids in the FF of patients with unexplained infertility. The alterations in the lipid class accumulation were independent of the body mass index (BMI) and were altogether kept across the age groups. Potential lipid biomarkers for pregnancy outcomes showed a highly discriminative abundance in the FF of unexplained infertility patients. Lipid abundance distinguished IVF patients with unrecognized infertility and provided a potential means for the evaluation of female fertility.

Metabolic changes in follicular fluids of patients treated with recombinant versus urinary human chorionic gonadotropin for triggering ovulation in assisted reproductive technologies: a metabolomics pilot study

INTRODUCTION

The main goal of this retrospective cohort study is the assessment of the effects of administration of recombinant-hCG (r-hCG) versus urinary-hCG (u-hCG) on follicular fluid (FF) composition of women who underwent in vitro fertilization (IVF) treatments.

MATERIALS AND METHODS

We selected 70 patients with infertility attributable to tubal diseases, unexplained infertility, and male factor. Metabolomics analysis of their FFs was performed by ¹H nuclear magnetic resonance (¹H NMR) spectroscopy in combination with multivariate analysis to interpret the spectral data. Univariate statistical analysis was applied to investigate the possible correlations between clinical parameters and between clinical parameters and metabolites identified by NMR.

RESULTS

According to the type of hCG used, significant differences were detected in FFs of women with male factor and unexplained infertility, both in qualitative and quantitative terms, for some metabolites as cholesterol, citrate, creatine, β-hydroxybutyrate, glycerol, lipids, amino acids (Glu, Gln, His, Val, Lys) and glucose. No significant difference was observed in women with tubal diseases. Besides, the number of MII oocytes in the u-hCG-treated groups correlates positively with glutamate in tubal disease and with glycerol in unexplained infertility. In the r-hCG-treated groups, the number of MII oocytes correlates positively with lipid in tubal disease, positively with citrate and negatively with glucose in male infertility.

CONCLUSIONS

Metabolite composition of FF changes according to different type of hCG treatment and this can be related to oocyte development and subsequent outcome. According to the data of this study, different types of hCG should be used in relation to the diagnosis of infertility to obtain better results in inducing oocyte maturation in women undergoing IVF.

Study of the Metabolomics of Equine Preovulatory Follicular Fluid: A Way to Improve Current In Vitro Maturation Media

Production of equine embryos in vitro is currently a commercial technique and a reliable way of obtaining offspring. In order to produce those embryos, immature oocytes are retrieved from postmortem ovaries or live mares by ovum pick-up (OPU), matured in vitro (IVM), fertilized by intracytoplasmic sperm injection (ICSI), and cultured until day 8-10 of development. However, at best, roughly 10% of the oocytes matured in vitro and followed by ICSI end up in successful pregnancy and foaling, and this could be due to suboptimal IVM conditions. Hence, in the present work, we aimed to elucidate the major metabolites present in equine preovulatory follicular fluid (FF) obtained from postmortem mares using proton nuclear magnetic resonance spectroscopy (¹H-NMR). The results were contrasted against the composition of the most commonly used media for equine oocyte IVM: tissue culture medium 199 (TCM-199) and Dulbecco's modified eagle medium/nutrient mixture F-12 Ham (DMEM/F-12). Twenty-two metabolites were identified in equine FF; among these, nine of them are not included in the composition of DMEM/F-12 or TCM-199 media, including (mean ± SEM): acetylcarnitine (0.37 ± 0.2 mM), carnitine (0.09 ± 0.01 mM), citrate (0.4 ± 0.04 mM), creatine (0.36 ± 0.14 mM), creatine phosphate (0.36 ± 0.05 mM), fumarate (0.05 ± 0.007 mM), glucose-1-phosphate (6.9 ± 0.4 mM), histamine (0.25 ± 0.01 mM), or lactate (27.3 ± 2.2 mM). Besides, the mean concentration of core metabolites such as glucose varied (4.3 mM in FF vs. 5.55 mM in TCM-199 vs. 17.5 mM in DMEM/F-12). Hence, our data suggest that the currently used media for equine oocyte IVM can be further improved.

Metabolomic alternations of follicular fluid of obese women undergoing in-vitro fertilization treatment

Obesity exerts negative effects on the metabolic homeostasis of cells in various tissues, but how it influences ovum metabolism is not fully understood. Previous studies demonstrate that oocyte genes that regulate oxidative stress, lipid metabolism, and inflammation are highly expressed in obese women. However, the metabolic effects of these genetic variations are not clear. To address this gap, we conducted an exploratory evaluation of follicular fluid (FF) metabolites in underweight, normal-weight, overweight, and obese women undergoing in vitro fertilization (IVF) treatment. The FF samples from the underweight (Group A, n = 40), normal-weight (Group B, n = 40), overweight (Group C, n = 40), and obese women (Group D, n = 40) were analyzed using ultra-performance liquid chromatography high-resolution mass spectrometry. A novel, high-coverage, semi-targeted metabolomics method (SWATH to MRM) and a targeted metabolomics method were employed to identify and verify the differential metabolites between the four groups. Sixteen differentially expressed FF metabolites were identified. Increase of BMI was associated with upregulation of 5 metabolites, ganoderiol H, LPI (18:3), sedoheptulose 1,7-bisphosphate, austalide L and 2 - {[hydroxyl (3-hydroxy-4-methoxyphenylmethylidene] amino} acetic acid, and downregulation of 5 metabolites, 1-phenyl-1,3-elcosanedione, retinol acetate, p-Cresol sulfate, setariol and arachidonyl carnitine. These metabolites were enriched in different metabolic pathways of retinol metabolism and fatty acid metabolism. These obesity-related differential metabolites provide a pathogenesis mechanism that explains the decline of oocyte development during obesity. These results suggest that obesity affects follicular environment prior to pregnancy, a time-window that may be important for lifestyle interventions to decrease obesity levels.

The cytokine profile of follicular fluid changes during ovarian ageing

OBJECTIVE

Ovarian ageing is one of the commonest causes of infertility in patients consulting for assisted reproductive technology. The composition of the follicular fluid (FF), which reflects the exchanges between the oocyte and its microenvironment, has been extensively investigated to determine the metabolic pathways involved in various ovarian disorders. Considering the importance of cytokines in folliculogenesis, we focused on the cytokine profile of the FF during ovarian ageing.

MATERIAL AND METHODS

Our cross-sectional study assesses the levels of 27 cytokines and growth factors in the FF of two groups of women undergoing in vitro fertilization. One group included 28 patients with ovarian ageing clinically characterized by a diminished ovarian reserve (DOR), and the other group included 29 patients with a normal ovarian reserve (NOR), serving as controls.

RESULTS

With univariate analysis, the cytokine profile was found to differ significantly between the two groups. After adjustment of the p-values, platelet-derived growth factor-BB (PDGF-BB) was the only cytokine with a significantly lower concentration in the DOR group (7.34 ± 16.11 pg/mL) than in the NOR group (24.39 ± 41.38 pg/mL) (p = 0.005), independently of chronological age.

CONCLUSION

Thus, PDGF-BB would seem to be implicated in the physiopathology of DOR, potentially in relation to its role in folliculogenesis or in the protection against oxidative stress.

Resolvin E1 in Follicular Fluid Acts as a Potential Biomarker and Improves Oocyte Developmental Competence by Optimizing Cumulus Cells

Metabolic profile of follicular fluid (FF) has been investigated to look for biomarkers for oocyte quality. Resolvin E1 (RvE1), a potent pro-resolving mediator, was reported to have protective action in cell function. The study aimed to examine the predictive value of RvE1 for oocyte quality and to explore the cellular mechanism of RvE1 in improving oocyte competence. Metabolic profiles of 80 FF samples showed a higher level of RvE1 in group A (blastocysts scored ≥ B3BC and B3CB according to Gardner's blastocyst scoring system, N = 36) than that of group B (blastocysts scored < B3BC and B3CB, N = 44, P = 0.0018). The receiver operating characteristic (ROC) curve analysis showed that RvE1 level in FF below 8.96 pg/ml (AUC:0.75; 95%CI: 0.64-0.86; P = 0.00012) could predict poor oocyte quality with specificity of 97.22%, suggesting RvE1 as a potential biomarker to exclude inferior oocytes. Besides, the level of RvE1 was found to be significantly lower in FF than in serum (57.49 to 17.62 pg/ml; P=.0037) and was gradually accumulated in the culture medium of cumulus cells (CCs) during cell culture, which indicated that RvE1 came from both blood exudates and local secretion. The in vitro experiment revealed thecellular mechanism of RvE1 in improvingoocyte qualityby decreasing the cumulus cellapoptotic rate and increasing cell viability and proliferation. It is the first time thatthe role of RvE1 in reproduction is explored. In conclusion, RvE1 is valuable as a potential exclusive biomarker for oocyte selection andplays a role in improving oocyte quality.