High bone morphogenetic protein-15 level in follicular fluid is associated with high quality oocyte and subsequent embryonic development

The Roles of GDF-9, BMP-15, BMP-4 and EMMPRIN in Folliculogenesis and In Vitro Fertilization

Growth differentiation factor 9 (GDF-9) contributes to early ovarian development and oocyte survival. Higher concentrations of GDF-9 in follicular fluid (FF) are associated with oocyte nuclear maturation and optimal embryo development. In in vitro fertilization (IVF), GDF-9 affects the ability of the oocyte to fertilize and subsequent embryonic development. Bone morphogenetic protein 15 (BMP-15) is involved in the regulation of ovarian function and affects oocyte development. During IVF, BMP-15 contributes to the formation of competent blastocysts. BMP-15 may play a role in embryo implantation by affecting endometrial receptivity. Bone morphogenetic protein 4 (BMP-4) is involved in the regulation of follicle growth and development and affects granulosa cell (GC) differentiation. In relation to IVF, BMP-4 is important for embryonic development, influences cell fate and differentiation, and plays a role in facilitating embryo-endometrial interactions during the implantation process. Extracellular matrix metalloproteinase inducer (EMMPRIN) is associated with ovulation and follicle rupture, promotes the release of mature eggs, and affects the modification of the extracellular matrix of the follicular environment. In IVF, EMMPRIN is involved in embryo implantation by modulating the adhesive properties of endometrial cells and promotes trophoblastic invasion, which is essential for pregnancy to occur. The purpose of the current article is to review the studies and recent findings of GDF-9, BMP-15, BMP-4 and EMMPRIN as fundamental factors in normal follicular development and in vitro fertilization.

Implication of Novel BMP15 and GDF9 Variants in Unexpected Poor Ovarian Response

Unexpected poor ovarian response (UPOR) occurs when nine or fewer oocytes are retrieved from a young patient with normal ovarian reserve. Bone morphogenetic protein15 (BMP15) and growth differentiation factor 9 (GDF9) are two oocyte-specific factors with pivotal role in folliculogenesis. The aim of this study was to assess the relation between BMP15 and GDF9 variants with UPOR. Hundred women aged ≤ 39 with AMH ≥ 1.27 IU/ml participated as UPOR and normal ovarian responders (NOR) based on their oocyte number. Each group consisted of 50 patients. After genomic DNA extraction, the entire exonic regions of BMP15 and GDF9 were amplified and examined by direct sequencing. Western blotting was performed to determine the expression levels of BMP15 and GDF9 in follicular fluid. Additionally, in silico analysis was applied to predict the effect of discovered mutations. From four novel variants of BMP15 and GDF9 genes, silent mutations (c.744 T > C) and (c.99G > A) occurred in both groups, whereas missense variants: c.967-968insA and c.296A > G were found exclusively in UPORs. The latter variants caused reduction in protein expression. Moreover, the mutant allele (T) in a GDF9 polymorphism (C447T) found to be more in NOR individuals (58% NOR vs. 37% UPOR (OR = 2.3, CI 1.32-4.11, p = 0.004).The novel missense mutations which were predicted as damaging, along with other mutations that happened in UPORs might result in ovarian resistance to stimulation. The mutant allele (T) in C447T polymorphism has a protective effect. It can be concluded that there is an association between BMP15 and GDF9 variants and follicular development and ovarian response.

Growth factors and female reproduction in vertebrates

Female reproductive efficiency is influenced by the outcomes of various processes, including folliculogenesis, apoptosis, response to gonadotropin signaling, oocyte maturation, and ovulation. The role of hormones in regulating these processes and other reproductive activities has been well established. It is becoming increasingly evident that in addition to well-characterized hormones, growth factors play vital roles in regulating some of these reproductive activities. Growth factors and their receptors are widely distributed in vertebrate ovaries at different stages of ovarian development, indicating their involvement in intraovarian reproductive functions. In the ovary, cell surface receptors allow growth factors to regulate intraovarian reproductive activities. Understanding these actions in the reproductive axis would provide a tool to target growth factors and/or their receptors to yield desirable reproductive outcomes. These include enrichment of in vitro maturation and fertilization culture media, and management of infertility. This review discusses some widely characterized growth factors belonging to the TGF, EGF, IGF, FGF, and BDNF family of peptides and their role in female reproduction in vertebrates, with a focus on mammals.

Potential biomarkers to predict return to fertility after discontinuation of female contraceptives-looking to the future

Nowadays there are multiple types of contraceptive methods, from reversible to permanent, for those choosing to delay pregnancy. Misconceptions about contraception and infertility are a key factor for discontinuation or the uptake of family planning methods. Regaining fertility (the ability to conceive) after contraceptive discontinuation is therefore pivotal. Technical studies to date have evaluated return to fertility by assessing pregnancy as an outcome, with variable results, or return to ovulation as a surrogate measure by assessing hormone levels (such as progesterone, LH, FSH) with or without transvaginal ultrasound. In general, relying on time to pregnancy as an indicator of return to fertility following contraceptive method discontinuation can be problematic due to variable factors independent of contraceptive effects on fertility, hormone clearance, and fertility recovery. Since the ability to conceive after contraceptive method discontinuation is a critical factor influencing product uptake, it is important to have robust biomarkers that easily and accurately predict the timing of fertility return following contraception and isolate that recovery from extrinsic and circumstantial factors. The main aim of this review is to summarize the current approaches, existing knowledge, and gaps in methods of evaluating return-to-fertility as well as to provide insights into the potential of new biomarkers to more accurately predict fertility restoration after contraceptive discontinuation. Biomarker candidates proposed in this document include those associated with folliculogenesis, cumulus cell expansion, follicular rupture and ovulation, and endometrial transport and receptivity which have been selected and scored on predefined criteria meant to evaluate their probable viability for advancement. The review also describes limitations, regulatory requirements, and a potential path to clinically testing these selected biomarkers. It is important to understand fertility restoration after contraceptive method discontinuation to provide users and health providers with accurate evidence-based information. Predictive biomarkers, if easy and low-cost, have the potential to enable robust evaluation of RTF, and provide potential users the information they desire when selecting a contraceptive method. This could lead to expanded uptake and continuation of modern contraception and inform the development of new contraceptive methods to widen user's family planning choices.

Association of Polymorphisms in FSHR, INHA, ESR1, and BMP15 with Recurrent Implantation Failure

Recurrent implantation failure (RIF) refers to two or more unsuccessful in vitro fertilization embryo transfers in the same individual. Embryonic characteristics, immunological factors, and coagulation factors are known to be the causes of RIF. Genetic factors have also been reported to be involved in the occurrence of RIF, and some single nucleotide polymorphisms (SNPs) may contribute to RIF. We examined SNPs in FSHR, INHA, ESR1, and BMP15, which have been associated with primary ovarian failure. A cohort of 133 RIF patients and 317 healthy controls consisting of all Korean women was included. Genotyping was performed by Taq-Man genotyping assays to determine the frequency of the following polymorphisms: FSHR rs6165, INHA rs11893842 and rs35118453, ESR1 rs9340799 and rs2234693, and BMP15 rs17003221 and rs3810682. The differences in these SNPs were compared between the patient and control groups. Our results demonstrate a decreased prevalence of RIF in subjects with the FSHR rs6165 A>G polymorphism [AA vs. AG adjusted odds ratio (AOR) = 0.432; confidence interval (CI) = 0.206-0.908; p = 0.027, AA+AG vs. GG AOR = 0.434; CI = 0.213-0.885; p = 0.022]. Based on a genotype combination analysis, the GG/AA (FSHR rs6165/ESR1 rs9340799: OR = 0.250; CI = 0.072-0.874; p = 0.030) and GG-CC (FSHR rs6165/BMP15 rs3810682: OR = 0.466; CI = 0.220-0.987; p = 0.046) alleles were also associated with a decreased RIF risk. Additionally, the FSHR rs6165GG and BMP15 rs17003221TT+TC genotype combination was associated with a decreased RIF risk (OR = 0.430; CI = 0.210-0.877; p = 0.020) and increased FSH levels, as assessed by an analysis of variance. The FSHR rs6165 polymorphism and genotype combinations are significantly associated with RIF development in Korean women.

Non-invasive assessment of oocyte developmental competence

Oocyte quality is a key factor influencing IVF success. The oocyte and surrounding cumulus cells, known collectively as the cumulus oocyte complex (COC), communicate bi-directionally and regulate each other's metabolic function to support oocyte growth and maturation. Many studies have attempted to associate metabolic markers with oocyte quality, including metabolites in follicular fluid or 'spent medium' following maturation, gene expression of cumulus cells and measuring oxygen consumption in medium surrounding COCs. However, these methods fail to provide spatial metabolic information on the separate oocyte and cumulus cell compartments. Optical imaging of the autofluorescent cofactors - reduced nicotinamide adenine dinucleotide (phosphate) [NAD(P)H] and flavin adenine dinucleotide (FAD) - has been put forward as an approach to generate spatially resolved measurements of metabolism within individual cells of the COC. The optical redox ratio (FAD/[NAD(P)H+FAD]), calculated from these cofactors, can act as an indicator of overall metabolic activity in the oocyte and cumulus cell compartments. Confocal microscopy, fluorescence lifetime imaging microscopy (FLIM) and hyperspectral microscopy may be used for this purpose. This review provides an overview of current optical imaging techniques that capture the inner biochemistry within cells of the COC and discusses the potential for such imaging to assess oocyte developmental competence.

Extracellular cell-free RNA profile in human large follicles and small follicles

Background: Previous studies have shown that a large number of valuable and functional cell-free RNAs (cfRNAs) were found in follicular fluid. However, the species and characteristics of follicular fluid cfRNAs have not been reported. Furthermore, their implications are still barely understood in the evaluation of follicular fluid from follicles of different sizes, which warrants further studies.

Objective: This study investigated the landscape and characteristics of follicular fluid cfRNAs, the source of organization, and the potential for distinguishing between follicles of different sizes.

Methods: Twenty-four follicular fluid samples were collected from 20 patients who received in vitro fertilization (n = 9) or ICSI (n = 11), including 16 large follicular fluid and 8 small follicular fluid samples. Also, the cfRNA profile of follicular fluid samples was analyzed by RNA sequencing.

Results: This result indicated that the concentration of follicular fluid cfRNAs ranged from 0.78 to 8.76 ng/ml, and fragment length was 20–200 nucleotides. The concentration and fragment length of large follicular fluid and small follicular fluid samples were not significantly different (p > 0.05). The technical replica correlation of follicular fluid samples ranged from 0.3 to 0.9, and the correlation of small follicular fluid samples was remarkably (p < 0.001) lower than that of large follicular fluid samples. Moreover, this study found that cfRNAs of the follicular fluid could be divided into 37 Ensembl RNA biotypes, and a large number of mRNAs, circRNAs, and lncRNAs were observed in the follicular fluid. The number of cfRNAs in large follicular fluid was remarkably (p < 0.05) higher than that of small follicular fluid. Furthermore, the follicular fluid contained a large amount of intact mRNA and splice junctions and a large number of tissue-derived RNAs, which are at a balanced state of supply and elimination in the follicular fluid. KEGG pathway analysis showed that differentially expressed cfRNAs were enriched in several pathways, including thyroid hormone synthesis, the cGMP-PKG signaling pathway, and inflammatory mediator regulation of TRP channels. In addition, we further showed that four cfRNAs (TK2, AHDC1, PHF21A, and TTYH1) serve as a potential indicator to distinguish the follicles of different sizes. The ROC curve shows great potential to predict follicular fluid from follicles of different sizes [area under the curve (AUC) > 0.88].

Conclusion: Overall, our study revealed that a large number of cfRNAs could be detected in follicular fluid and could serve as a potential non-invasive biomarker in distinguishing between follicles of different sizes. These results may inform the study of the utility and implementation of cfRNAs in clinical practice.

Comparative analyses in transcriptome of human granulosa cells and follicular fluid micro-environment between poor ovarian responders with conventional controlled ovarian or mild ovarian stimulations

BACKGROUND

Both mild and conventional controlled ovarian stimulation are the frequently used protocols for poor ovarian responders. However, there are some debates about which treatment is better. Moreover, little is known about the follicular physiology after the two ovarian stimulation protocols. This study was intended to investigate the features in granulosa cells and follicular fluid micro-environment after the two different ovarian stimulation protocols in poor responders.

METHODS

Granulosa cells RNA were sequenced using Illumina Hiseq technology. Specific differently expressed genes and proteins were verified by real-time quantitative PCR and Western blot analysis. Moreover, hormone and cytokine concentrations in the follicular fluid were measured by electrochemiluminescence immunoassay and enzyme-linked immunoabsorbent assay. The correlation between the results of molecular experiments and the laboratory outcomes were analyzed by Spearman correlation analysis.

RESULTS

The differentially expressed genes between the two groups were involved in 4 signaling pathways related to the follicular development; three proteins pertinent to the TGF-β signaling pathway were expressed differently in granulosa cells between the two, and the constituents in the follicular fluid were also different. Further, a correlation between the TGF-β signaling pathway and the good-quality embryo was observed.

CONCLUSIONS

The present study made a comparison for the first time in the transcriptome of human granulosa cells and the follicular fluid micro-environment between poor responders with the conventional controlled ovarian stimulation or the mild ovarian stimulation, showing that the TGF-β signaling pathway may correlate with the good-quality of embryos in the mild group, which may be instrumental to the choice of optimal management for IVF patients.

The follicular fluid adipocytokine milieu could serve as a prediction tool for fertility treatment outcomes

RESEARCH QUESTION

Can the adipocytokine milieu of the follicular niche improve the ability to predict treatment outcomes in infertile patients?

DESIGN

Follicular fluid samples from overweight patients were analysed and compared with samples from matched normal-weight patients. Concentrations of adiponectin, chemerin, C-reactive protein, interleukin-6 (IL-6), IL-10, IL-18, insulin, leptin, prolactin, resistin, tumour necrosis factor alpha (TNF-α) and bone morphogenetic protein-15 (BMP-15) were assessed by multiple magnetic bead immunoassay (MMBI) and enzyme-linked immunosorbent assay and correlated with fertility treatment outcomes.

RESULTS

Analysis of samples from 22 overweight and 22 normal-weight patients demonstrated that TNF-α can predict oocyte maturation rate. When stratified by body mass index (BMI), IL-10 emerges as a better predictor of oocyte maturation in normal-weight patients. Prolactin was a negative predictor for fertilization rate in the full cohort, and this prediction power was lost upon stratification. No adipocytokines were predictive of blastulation rate, and only age remained predictive. BMP-15 was a strong predictor of high-quality blastulation in the full cohort, more so in the normal-weight population.

CONCLUSIONS

The adipocytokine milieu of the follicular fluid provides a snapshot of the growing oocyte's environment and can help predict fertility treatment outcomes, fine-tuning understanding of the dysregulation caused by increasing BMI. Inflammatory cytokines can predict oocyte maturation; prolactin, oocyte competence; and BMP-15, high-quality blastulation. Further analysis of these findings with a larger sample size and assessing individual oocytes will help shed more light on the clinical significance of these findings.

BMP-9 downregulates StAR expression and progesterone production by activating both SMAD1/5/8 and SMAD2/3 signaling pathways in human granulosa-lutein cells obtained from gonadotropins induced ovarian cycles

Bone morphogenetic proteins (BMPs) are expressed in different cell types of the human ovarian follicle and play important roles in the regulation of ovarian function. BMP-9, also known as growth differentiation factor-2 (GDF-2), belongs to the transforming growth factor-beta (TGF-β) superfamily. BMP-9 is mainly synthesized in the liver and secreted into the blood which allows it to regulate various physiological and pathological functions. To date, the expression of BMP-9 in the human ovary and its function in human granulosa cells remains unknown. In the present study, we detect the protein expression of BMP-9 in the human follicular fluid. Using the primary culture of human granulosa-lutein (hGL) cells obtained from patients undergoing in vitro fertilization as a cell model, we show that treatment with BMP-9 downregulates steroidogenic acute regulatory protein (StAR) expression and suppresses progesterone (P4) production. The expression levels of the P450 side-chain cleavage enzyme (P450scc) and 3β-hydroxysteroid dehydrogenase (3β-HSD) are not affected by BMP-9 treatment. Mechanistically, treatment of hGL cells with BMP-9 activates both SMAD1/5/8 and SMAD2/3 signaling pathways. Blocking the activations of SMAD1/5/8 and SMAD2/3 by pharmacological inhibitors or knockdown of SMAD4 attenuates the inhibitory effects of BMP-9 on StAR expression and P4 production. This study reveals a novel function of BMP-9 in the regulation of ovarian steroidogenesis.

Age-related decline in the expression of GDF9 and BMP15 genes in follicle fluid and granulosa cells derived from poor ovarian responders

Background

Growth differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15) genes play important roles in folliculogenesis. Altered expression of the two have been found among patients with poor ovarian response (POR). In this prospective cohort study, we have determined the expression of the GDF9 and BMP15 genes in follicle fluid (FF) and granulosa cells (GCs) derived from poor ovarian responders grouped by age, and explored its correlation with the outcome of in vitro fertilization and embryo transfer (IVF-ET) treatment.

Methods

A total of 196 patients with POR were enrolled from a tertiary teaching hospital. The patients were diagnosed by the Bologna criteria and sub-divided into group A (< 35 year old), group B (35–40 year old), and group C (> 40 year old). A GnRH antagonist protocol was conducted for all patients, and FF and GCs were collected after oocyte retrieval. Expression of the GDF9 and BMP15 genes in the FF and GCs was determined with enzyme-linked immunosorbent assay (ELISA), quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting.

Results

Compared with group C, groups A and B had significantly more two pronuclei (2PN) oocytes and transplantable embryos, in addition with higher rates of implantation and clinical pregnancy (P <  0.05). The expression level of GDF9 and BMP15 genes in the FF and GCs differed significantly among the three groups (P <  0.05), showing a trend of decline along with age. The ratio of GDF9/BMP15 mRNA levels were similar among the three groups (P > 0.05). The relative levels of GDF9 and BMP15 proteins in GCs have correlated with the relative mRNA levels in GCs and protein concentrations in FF (P <  0.05).

Conclusions

For poor ovarian responders, in particular those over 40, the expression of GDF9 and BMP15 is declined along with increased age and in accompany with poorer oocyte quality and IVF outcome, whilst the ratio of GDF9/BMP15 mRNA levels remained relatively constant.

Trial registration

Chinese Clinical Trial Registry Center (ChiCTR1800016107). Registered on 11 May 2018.

In vitro maturation on an agarose matrix improves the developmental competence of porcine oocytes

Oocytes in vivo generally mature in ovarian follicles that are soft, whereas oocytes that mature in vitro are on the hard surface of culture dishes. Embryonic ontogeny through organogenesis has greater ability in in vivo matured oocytes than it does in in vitro matured oocytes, indicating the importance of a soft culture matrix. In this study, we report the effect of using an agarose matrix as a culture substrate on the development of pig oocytes derived from medium antral follicles. The cumulus-oocyte complexes (COCs) retrieved from medium antral follicles were matured on noncoated (control) culture dishes or dishes coated with 1% and 2% (w/v) agarose matrices. Subsequently, the effect of the soft culture matrix on the developmental competence of porcine oocytes was assessed by analyzing cumulus expansion, blastocyst formation after parthenogenetic activation (PA), gene expression levels (ACTN4, BMP15, BAX, HIF1A, PFKP and VEGFA), TUNEL indices, BMP15 protein expression levels, cortical granule (CG) distribution, and intraoocyte ATP levels. In vitro maturation (IVM) of pig COCs using a 1% (w/v) agarose matrix resulted in significantly higher blastocyst formation, cumulus expansion, gene expression of BMP15, HIF1A and VEGFA, protein expression of BMP15, and intraoocyte ATP levels, and there was significantly reduced expression of a pro-apoptotic gene and ACTN4 gene and a reduction in TUNEL indices. These results demonstrate that the developmental competence of porcine oocytes can be effectively improved through IVM on a soft culture matrix made of agarose over what is observed using hard culture dishes.

Follicular wave dynamics and Growth factors gene expression in Braford heifers

The objectives of the present study were (experiment 1) to characterized development and dynamics of the dominant follicles (DF) and the corpus luteum (CL) to determine patterns of two (W2) and three (W3) follicular waves in beef heifers, and (experiment 2) to determine gene expression of growth factors gene expression in follicular cells of W2 and W3 heifer. Twenty-eight Braford heifers were used. Dominant follicular and CL were monitored daily by ultrasonography to identify the development W2 and W3 in heifers. Pre-ovulatory DF were aspirated on day 19 in W2 and on day 22 in W3 heifers. In W2 and W3, follicular cells (FC) of gene expression of growth differentiation factor 9, bone morphogenetic protein 15 (BMP15), fibroblast growth factor basic, transforming growth factor beta receptor 1, bone morphogenetic protein receptor type IB and fibroblast growth factor receptor 2 were evaluated. The regression of the DF of the first follicular wave and the emergency of the DF of the second follicular wave began later in the heifers W2 than in W3 (p = .02 and p < .01). The regression of the CL began earlier in the W2 than in W3 group (p < .01). Gene expression of growth factors and receptors was similar between groups. However, higher relative levels of BMP15 was observed in W2 group (p = .07). Results propose that wave patterns were regulated by the development time of the DF in the first wave and the life of the CL. Furthermore, higher levels of BMP15 could produce shorter life of CL. The present work suggest that ultrasonography associated with molecular assays could be used as an easy and effective tool to characterize follicular wave patterns.

Morphokinetic analysis of cleavage stage embryos and assessment of specific gene expression in cumulus cells independently predict human embryo development to expanded blastocyst: a preliminary study

To assess whether morphokinetic features at the cleavage stage together with specific gene expression in cumulus cells (CCs) may be used to predict whether human embryos are able to achieve the expanded blastocyst stage on day 5. Eighty-one embryos were cultured using the Geri plus® time-lapse system. Twenty-seven embryos progressing to the expanded blastocyst stage (BL group) were compared with thirty-five embryos showing developmental arrest (AR group) and nineteen reaching the stage of early or not fully expanded blastocyst (nBL group). The analyzed morphokinetic variables were pronuclear appearance (tPNa), pronuclear fading (tPNf), and completion of cleavage to two, three, four, and eight cells (t2, t3, t4, and t8). CCs were analyzed by RT-qPCR for bone morphogenetic protein 15 (BMP15), cytochrome c oxidase subunit II (COXII), ATP synthase subunit 6 (MT-ATP6), connexin 43 (Cx43), and heme oxygenase-1 (HO-1). Embryos of BL group showed a significantly faster kinetic. BMP15, COXII, and MT-ATP6 mRNA expression was significantly higher in CCs of BL group embryos, whereas Cx43 and HO-1 mRNA levels were higher in AR group. Kinetic parameters and gene expression were not significantly different between either the BL and nBL groups or the AR and nBL groups. ROC curves showed that the most predictive cut-offs were t2 < 26.25 for morphokinetics and COXII > 0.3 for gene expression. Multivariable logistic regression analysis showed that morphokinetic variables and gene expression were both valuable, independent predictors of embryo development to expanded blastocyst. Our results suggest the possibility of developing integrated prediction models for early embryo selection at the cleavage stage.

MicroRNA-21 as a regulator of human cumulus cell viability and its potential influence on the developmental potential of the oocyte

MicroRNA-21 is expressed in bovine, murine, and human cumulus cells with its expression in murine and bovine cumulus cells correlated with oocyte developmental potential. The aim of this study was to assess the relationship between cumulus cell MIR-21 and human oocyte developmental potential. These studies revealed that both the immature and mature forms of MicroRNA-21 (MIR-21-5p) were elevated in cumulus cells of oocytes that developed into blastocysts compared to cumulus cells of oocytes that arrested prior to blastocyst formation. This increase in MicroRNA-21 was observed regardless of whether the oocytes developed into euploid or aneuploid blastocysts. Moreover, MIR-21-5p levels in cumulus cells surrounding oocytes that either failed to mature or matured to metaphase II but failed to fertilize, were ≈50% less than the MIR-21-5p levels associated with oocytes that arrested prior to blastocyst formation. Why cumulus cells associated with oocytes of reduced developmental potential expressed less MIR-21-5p is unknown. It is unlikely due to reduced expression of either the receptors of growth differentiation factor 9 or rosha Ribonuclease III (DROSHA) and Dicer Ribonuclease III (DICER) which sequentially promote the conversion of immature forms of MicroRNA-21 to mature MicroRNA-21. Furthermore, cultured cumulus cells treated with a MIR-21-5p inhibitor had an increase in apoptosis and a corresponding increase in the expression of PTEN, a gene known to inhibit the AKT-dependent survival pathway in cumulus cells. These studies provide evidence for a role of MicroRNA-21 in human cumulus cells that influences the developmental potential of human oocytes.

Source and Follicular Fluid Treatment During the In Vitro Maturation of Recipient Oocytes Affects the Development of Cloned Pig Embryo

Pig cloning technique is valuable in agriculture, biomedicine, and life sciences. However, the full-term developmental efficiency of cloned pig embryos is only about 1%, which limits pig cloning application. The quality of recipient oocytes greatly affects the developmental competence of cloned pig embryos. Thus, this study investigated the effects of a recipient oocyte source (in vivo matured [IVVM] oocytes vs. slaughter house-derived in vitro matured [IVTM] oocytes), and follicular liquid treatment (slaughter house-derived immature follicle-derived fluid [IFF] vs. in vivo-matured follicle-derived fluid [MFF]) during the in vitro maturation (IVM) of oocytes on the development of the cloned pig embryos. Our results showed that using IVVM oocytes to replace IVTM oocytes as recipient oocytes, and using 10% MFF IVM medium to replace 10% IFF IVM medium could enhance the development of the cloned pig embryos. IFF and MFF contained different levels of oocyte quality-related proteins, resulting in different oocyte quality-related gene expression levels and reactive oxygen species levels between the 10% MFF medium-cultured oocytes and 10% IFF medium-cultured oocytes. This study provided useful information for enhancing the pig cloning efficiency by improving the quality of recipient oocytes.

The Role of Exosomes in Diseases Related to Infertility

Exosomes, small extracellular vesicles with diameters of 40-100nm, are generated through the fusion of multivessel with plasma membrane and secreted by a variety of living cells. Exosomes contain lipid bilayer membrane and releasable functionally active proteins, mRNA and microRNAs (miRNAs). This article reviews the latest progress of researches on exosomes in diseases that lead to infertility.

Bone Morphogenetic Protein 15 Knockdown Inhibits Porcine Ovarian Follicular Development and Ovulation

Bone morphogenetic protein 15 (BMP15) is strongly associated with animal reproduction and woman reproductive disease. As a multifunctional oocyte-specific secret factor, BMP15 controls female fertility and follicular development in both species-specific and dosage-sensitive manners. Previous studies found that BMP15 played a critical role in follicular development and ovulation rate in mono-ovulatory mammalian species, especially in sheep and human, but study on knockout mouse model implied that BMP15 possibly has minimal impact on female fertility of poly-ovulatory species. However, this needs to be validated in other poly-ovulatory species. To investigate the regulatory role of BMP15 on porcine female fertility, we generated a BMP15-knockdown pig model through somatic nuclear transfer technology. The BMP15-knockdown gilts showed markedly reduced fertility accompanied by phenotype of dysplastic ovaries containing significantly declined number of follicles, increased number of abnormal follicles, and abnormally enlarged antral follicles resulting in disordered ovulation, which is remarkably different from the unchanged fertility observed in BMP15 knockout mice. Molecular and transcriptome analysis revealed that the knockdown of BMP15 significantly affected both granulosa cells (GCs) and oocytes development, including suppression of cell proliferation, differentiation, and follicle stimulating hormone receptor (Fshr) expression, leading to premature luteinization and reduced estradiol (E2) production in GCs, and simultaneously decreased quality and meiotic maturation of oocyte. Our results provide in vivo evidence of the essential role of BMP15 in porcine ovarian and follicular development, and new insight into the complicated regulatory function of BMP15 in female fertility of poly-ovulatory species.

The role of FSH and TGF-β superfamily in follicle atresia

Most of the mammalian follicles undergo a degenerative process called “follicle atresia”. Apoptosis of granulosa cells is the main characteristic of follicle atresia. Follicle stimulating hormone (FSH) and the transforming growth factor β (TGF-β) superfamily have important regulatory functions in this process. FSH activates protein kinase A and cooperating with insulin receptor substrates, it promotes the PI3K/Akt pathway which weakens apoptosis. Both Smad or non-Smad signaling of the transforming growth factor β superfamily seem to be related to follicle atresia, and the effect of several important family members on follicle atresia is concluded in this article. FSH and TGF-β are likely to mutually influence each other and what we have already known about the possible underlying molecular mechanism is also discussed below.

Supplementation of maturation medium with CoQ10 enhances developmental competence of ovine oocytes through improvement of mitochondrial function

In vitro maturation (IVM) can impair the balance between antioxidant capacity and oxidative stress, and jeopardize embryo development by increasing oxidative stress, reducing energy metabolism, and causing improper meiotic segregation. Balancing the energy production and reduction of oxidative stress can be achieved by supplementation with coenzyme Q10 (CoQ10), an electron transporter in the mitochondrial inner membrane. To improve the in vitro production of ovine embryos, we studied the effect of CoQ10 supplementation during the maturation of sheep oocytes. A minimum of 100 cumulus-oocyte complexes (COCs) were matured in the presence of 15, 30, or 50 μM CoQ10 in three to five replicates; next, in vitro fertilization and culture in a subset of oocytes were done. Our data revealed that compared to control oocytes or other concentrations of CoQ10, supplementation with 30 µM CoQ10 resulted in a significant increase in blastocyst formation and hatching rates, improved the distribution, relative mass and potential membrane of mitochondria, decreased the levels of reactive oxygen species and glutathione and lessened the percentage of oocytes with misaligned chromosomes after spindle assembly. The relative expression levels of apoptosis markers CASPASE3 and BAX were significantly reduced in CoQ10-treated oocytes and cumulus cells whereas the relative expression level of GDF9, an oocyte-specific growth factor, significantly increased. In conclusion, supplementation with CoQ10 improves the quality of COCs and the subsequent developmental competence of the embryo.

Oocyte-Secreted Factors Synergize With FSH to Promote Aromatase Expression in Primary Human Cumulus Cells

CONTEXT

The role of growth differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15) on aromatase regulation is poorly understood in humans.

OBJECTIVE

Determine GDF9 and BMP15 effects on FSH stimulation of estradiol production in primary human cumulus granulosa cells (GCs). We hypothesized that the combination of GDF9 and BMP15 potentiates FSH-induced aromatase expression.

DESIGN

Primary human cumulus GCs in culture.

SETTING

University infertility center.

PATIENTS OR OTHER PARTICIPANTS

GCs of 60 women undergoing in vitro fertilization were collected.

INTERVENTIONS

Cells were treated with GDF9 and/or BMP15 (GB) in the presence or absence of FSH, dibutyryl cAMP, or SMAD inhibitors.

MAIN OUTCOME MEASURES

Promoter activity, mRNA, protein, and estradiol levels were quantified.

RESULTS

FSH and GB treatment increased CYP19A1 promoter activity, mRNA, and protein levels as well as estradiol when compared with cells treated with FSH only. GB treatment potentiated cAMP stimulation of aromatase and IGF2 stimulation by FSH. GB effects were inhibited by SMAD3 inhibitors and IGF1 receptor inhibitors. GB, but not FSH, stimulates SMAD3 phosphorylation.

CONCLUSION

The combination of GDF9 and BMP15 potently stimulates the effect of FSH and cAMP on CYP19a1 promoter activity and mRNA/protein levels. These effects translate into an increase in estradiol production. This potentiation seems to occur through activation of the SMAD2/3 and SMAD3 signaling pathway and involves, at least in part, the effect of the IGF system.

Connecting links between genetic factors defining ovarian reserve and recurrent miscarriages

PURPOSE

Approximately 1-2% of the women faces three or more successive spontaneous miscarriages termed as recurrent miscarriage (RM). Many clinical factors have been attributed so far to be the potential risk factors in RM, including uterine anomalies, antiphospholipid syndrome, endocrinological abnormalities, chromosomal abnormalities, and infections. However, in spite of extensive studies, reviews, and array of causes known to be associated with RM, about 50% cases encountered by treating physicians remains unknown. The aims of this study were to evaluate recent publications and to explore oocyte-specific genetic factors that may have role in incidence of recurrent miscarriages.

METHOD

Recent studies have identified common molecular factors contributing both in establishment of ovarian reserve and in early embryonic development. Also, studies have pointed out the relationship between the age-associated depletion of OR and increase in the risk of miscarriages, thus suggestive of an interacting biology. Here, we have gathered literature evidences in establishing connecting links between genetic factors associated with age induced or pathological OR depletion and idiopathic RM, which are the two extreme ends of female reproductive pathology.

CONCLUSION

In light of connecting etiological link between infertility and RM as reviewed in this study, interrogating the oocyte-specific genes with suspected roles in reproductive biology, in cases of unexplained RM, may open new possibilities in widening our understanding of RM pathophysiology.

GDF-9 and BMP-15 direct the follicle symphony

Understanding the physiology underlying the complex dialog between the oocyte and its surrounding somatic cells within the ovarian follicle has been crucial in defining optimal procedures for the development of clinical approaches in ART for women suffering from infertility and ovarian dysfunction. Recent studies have implicated oocyte-secreted factors like growth differentiation factor 9 (GDF-9) and bone morphogenetic protein 15 (BMP-15), members of the transforming growth factor-beta (TGFβ) superfamily, as potent regulators of folliculogenesis and ovulation. These two factors act as biologically active heterodimers or as homodimers in a synergistic cooperation. Through autocrine and paracrine mechanisms, the GDF-9 and BMP-15 system has been shown to regulate growth, differentiation, and function of granulosa and thecal cells during follicular development playing a vital role in oocyte development, ovulation, fertilization, and embryonic competence. The present mini-review provides an overview of recent findings relating GDF-9 and BMP-15 as fundamental factors implicated in the regulation of ovarian function and discusses their potential role as markers of oocyte quality in women.

Influence of follicular fluid and cumulus cells on oocyte quality: clinical implications

An equilibrium needs to be established by the cellular and acellular components of the ovarian follicle if developmental competence is to be acquired by the oocyte. Both cumulus cells (CCs) and follicular fluid (FF) are critical determinants for oocyte quality. Understanding how CCs and FF influence oocyte quality in the presence of deleterious systemic or pelvic conditions may impact clinical decisions in the course of managing infertility. Given that the functional integrities of FF and CCs are susceptible to concurrent pathological conditions, it is important to understand how pathophysiological factors influence natural fertility and the outcomes of pregnancy arising from the use of assisted reproduction technologies (ARTs). Accordingly, this review discusses the roles of CCs and FF in ensuring oocyte competence and present new insights on pathological conditions that may interfere with oocyte quality by altering the intrafollicular environment.

Screening of miRNAs in human follicular fluid reveals an inverse relationship between microRNA-663b expression and blastocyst formation

RESEARCH QUESTION

Are miRNAs found in follicular fluid related to blastocyst formation from the corresponding oocytes?

DESIGN

In this study, 91 individual follicular fluid samples from single follicles containing mature oocytes from 91 women were collected and classified into group 1 (n = 38) with viable blastocysts, and group 2 (n = 53) with no blastocyst. TaqMan human miRNA cards and quantitative reverse transcription polymerase chain reaction were used to identify differently expressed follicular fluid miRNAs between the two groups.

RESULTS

We found MIR-663B to be significantly differentially expressed in follicular fluid of oocytes that yielded viable blastocysts versus those that did not develop into blastocysts (14.16 ± 7.00 versus 23.68 ± 17.02; P = 0.019), as well as for those which develop into blastocysts with good morphology versus those with poor morphology (11.69 ± 3.49 versus 20.16 ± 9.33; P = 0.003).

CONCLUSIONS

MIR-663B expression levels in human follicular fluid samples were significantly negatively related to viable blastocyst formation and may become an objective evaluation criterion for embryo development potential after IVF.

Involvement of Bone Morphogenetic Proteins (BMP) in the Regulation of Ovarian Function

Primordial germ cells migrate to the fetal gonads and proliferate during gestation to generate a fixed complement of primordial follicles, the so-called ovarian reserve. Primordial follicles comprise an oocyte arrested at the diplotene stage of meiosis, surrounded by a layer of pregranulosa cells. Activation of primordial follicles to grow beyond this arrested stage is of particular interest because, once activated, they are subjected to regulatory mechanisms involved in growth, selection, maturation, and ultimately, ovulation or atresia. The vast majority of follicles succumb to atresia and are permanently lost from the quiescent or growing pool of follicles. The bone morphogenetic proteins (BMPs), together with other intraovarian growth factors, are intimately involved in regulation of follicle recruitment, dominant follicle selection, ovulation, and atresia. Activation of primordial follicles appears to be a continuous process, and the number of small antral follicles at the beginning of the menstrual cycle provides an indirect indication of ovarian reserve. Continued antral follicle development during the follicular phase of the menstrual cycle is driven by follicle stimulating hormone (FSH) and luteinizing hormone (LH) in conjunction with many intraovarian growth factors and inhibitors interrelated in a complex web of regulatory balance. The BMP signaling system has a major intraovarian role in many species, including the human, in the generation of transcription factors that influence proliferation, steroidogenesis, cell differentiation, and maturation prior to ovulation, as well as formation of corpora lutea after ovulation. At the anterior pituitary level, BMPs also contribute to the regulation of gonadotrophin production.

Distinct effect of fetal bovine serum versus follicular fluid on multipotentiality of human granulosa cells in in vitro condition

This study aimed to develop an appropriate medium for preservation of multipotentiality in human granulosa cells. To compare the possible effect of different media supplemented with follicular fluid or fetal bovine serum, granulosa cells were cultured in vitro over a period of 14 days. Stemness feature and any alteration in the cell phenotype were monitored using colony count assay and flow cytometry analysis by monitoring the expression of Oct3/4 and GATA-4 factors. Transcript expression level of Sox-2, Klf-4, and Nanog were investigated using quantitative real-time PCR analysis. Cells were cultured in the medium supplement with follicular fluid showed normal cell morphology and epithelial-like appearance, however, cells treated with fetal bovine serum, exhibited the clonogenic potential of granulosa cells which was increased after exposure to follicular fluid after 14 days (p < 0.05). Flow cytometry analysis revealed a significant reduction in the protein level of GATA-4 in cells cultured in presence of follicular fluid compared with cells received fetal bovine serum (p < 0.001). Quantitative real-time PCR analysis disclosed reduction of Sox-2, Klf-4 and Nanog levels in cells exposed to fetal bovine serum. Our experiment showed the exposure of human granulosa cells to follicular fluid efficiently preserves the stemness characteristics of the cells.

Molecular Aspects and Clinical Relevance of GDF9 and BMP15 in Ovarian Function

Growth and differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15) are oocyte-secreted factors with a leading role in the control of ovarian function in female reproduction, modulating both the cell fate of the somatic granulosa cells and the quality and developmental competence of the egg. This short review aims to consolidate the molecular aspects of GDF9 and BMP15 and their integral actions in female fertility to understand particularly their effects on oocyte quality and fetal growth. The significant consequences of mutations in the GDF9 and BMP15 genes in women with dizygotic twins as well as the clinical relevance of these oocyte factors in the pathogenesis of primary ovarian insufficiency and polycystic ovary syndrome are also addressed.

N-Acetylcysteine Compared to Metformin, Improves The Expression Profile of Growth Differentiation Factor-9 and Receptor Tyrosine Kinase c-Kit in The Oocytes of Patients with Polycystic Ovarian Syndrome

Background

Paracrine disruption of growth factors in women with polycystic ovarian syndrome (PCOS) results in production of low quality oocyte, especially following ovulation induction. The aim of this study was to investigate the effects of metformin (MET), N-acetylcysteine (NAC) and their combination on the hormonal levels and expression profile of GDF-9, BMP-15 and c-kit, as hallmarks of oocyte quality, in PCOS patients.

MATERIALS AND METHODS

This prospective randomized, double-blind, placebo controlled trial aims to study the effects of MET, NAC and their combination (MET+NAC) on expression of GDF-9, BMP-15 and c-kit mRNA in oocytes [10 at the germinal vesicle (GV) stage, 10 at the MI stage, and 10 at the MII stage from per group] derived following ovulation induction in PCOS. Treatment was carried out for six weeks, starting on the third day of previous cycle until oocyte aspiration. The expression of GDF9, BMP15 and c-kit were determined by quantitative real time polymerase chain reaction (RT-qPCR) and western blot analysis. Data were analyzed with one-way ANOVA.

RESULTS

The follicular fluid (FF) level of c-kit protein significantly decreased in the NAC group compared to the other groups. Significant correlations were observed between the FF soluble c-kit protein with FF volume, androstenedione and estradiol. The GDF-9 expression in unfertilized mature oocytes were significantly higher in the NAC group compared to the other groups (P<0.001). Similar difference was not observed between the MET, NAC+MET and control groups. The c-kit expression in unfertilized mature oocytes were significantly lower in the NAC group compared to the other groups (P<0.001). Similar difference was not observed between the MET, NAC+MET and control groups (Registration number: IRCT201204159476N1).

CONCLUSION

We concluded that NAC can improve the quality of oocytes in PCOS.

Proteomic analysis of human follicular fluid in poor ovarian responders during in vitro fertilization

Poor ovarian response (POR) in controlled ovarian stimulation is often observed during in vitro fertilization and embryo transfer cycles and it is a major problem. A POR has been found to be related to several factors, including advanced age, high body mass index, and history of ovarian or pelvic surgery. However, it is difficult to predict POR, as there are no specific biomarkers known. In this study, we used quantitative proteomic analyses to investigate potential biomarkers that can predict poor response during in vitro fertilization based on follicular fluid samples. A total of 1079 proteins were identified using a high-resolution orbitrap mass spectrometer coupled online to a nanoflow-LC system. It is notable that 65 upregulated and 66 downregulated proteins were found to be functionally enriched in poor responders. We also validated these differentially expressed proteins using a triple-quadrupole mass spectrometer for quantification of targeted proteins. Of the differentially expressed proteins, three proteins (pregnancy zone protein, renin, and sushi repeat-containing protein SRPX) were regarded as statistically significant (p < 0.05).

GDF9 and BMP15 Expressions and Fine Structure Changes During Folliculogenesis in Polycystic Ovary Syndrome

Background:

Polycystic ovary syndrome is the most frequently seen endocrine disorder in women of reproductive age with a prevalence of about 10%.

Aims:

To investigate the efficiency of growth differentiation factor 9 and bone morphogenetic protein 15 during folliculogenesis in a dehydroepiandrosterone-induced mouse Polycystic ovary syndrome model.

Study Design:

Animal experimentation.

Methods:

Mice were divided into 3 groups: control, vehicle and Polycystic ovary syndrome. Polycystic ovary syndrome model mice were developed by the injection of dehydroepiandrosterone dissolved in 0.1 mL of sesame oil. Ovarian tissues were examined for growth differentiation factor 9 and bone morphogenetic protein 15 using immunofluorescent labelling and electron microscopic examinations.

Results:

The immunoreactivity of growth differentiation factor 9 and bone morphogenetic protein 15 proteins decreased (p<0.05) in the Polycystic ovary syndrome group (27.73±8.43 and 24.85±7.03, respectively) compared with the control group (33.72±11.22 and 31.12±11.05, respectively) and vehicle group (33.95±10.75 and 29.99±10.72, respectively). Apoptotic changes were observed in granulosa cells, lipid vacuoles increased in Theca cells and thickening and irregularities were noted in the basal lamina of granulosa cells. An increased electron density in the zona pellucida in some of the multilaminar primary and secondary follicles in the Polycystic ovary syndrome model was also observed at the ultrastructural level.

Conclusion:

These results suggest that the decrease in the growth differentiation factor 9 and bone morphogenetic protein 15 expression initiated at the primary follicle stage effect the follicle development and zona pellucida structure and may cause subfertility or infertility in Polycystic ovary syndrome.

[Quality of oocytes and embryos from women with polycystic ovaries syndrome: State of the art]

The frequency of polycystic ovary syndrome (PCOS) and the consequent fertility disorders cause many difficulties in the management of the assisted reproductive technics. Some studies are focused on different additional treatments, stimulation protocols or techniques that could optimize the in vitro fertilization cycles. The quality of the oocytes and embryos of these patients is also an outstanding issue. They remain difficult to actually evaluate during management, and none of the few published studies on this subject demonstrated any inferiority, compared to control patients. However, many differences have been highlighted, studying intra- and extra-ovarian factors. The advent of new genetic techniques could allow a better understanding of the pathophysiological mechanisms of the syndrome, as well as refining the evaluation of oocytes and embryos, in order to better predict the results of in vitro fertilization attempts. Pregnancy and birth rates, however, appear to be comparable to those of the general population.

Developmental competence of Dromedary camel (Camelus dromedarius) oocytes selected using brilliant cresyl blue staining

The objectives of the present studies were to investigate the developmental capacity of dromedary camel oocytes selected by brilliant cresyl blue (BCB) staining and to investigate the expression of select transcripts in germinal vesicle (GV) stage oocytes. These transcripts included BMP15 and GDF9 as important transcripts for folliculogenesis and oocyte development, Zar1 and Mater as maternal transcripts required for embryonic development, Cyclin B1 and CDK1 as cell cycle regulators and Oct4 and STAT3 as transcription factors. Dromedary camel oocytes were retrieved from ovaries collected at a local slaughterhouse. After exposure to BCB staining, cumulus–oocyte complexes (COCs) from BCB+, BCB− and control (selected based on morphological criteria) groups were subjected toin vitromaturation,in vitrofertilization andin vitroculture. For gene expression studies, after BCB staining cumulus cells were stripped off and the completely denuded GV stage oocytes were used for RT-PCR analysis of selected transcripts. BCB+ oocytes showed higher maturation, and fertilization rates compared with BCB− and control groups. Indices of early embryonic development, namely, cleavage at 48 hours post insemination (hpi), and development to morula at day 5 and day 7 blastocyst rates were also significantly higher in the BCB+ group. RT-PCR revealed a higher expression of BMP15, GDF9, Zar1, Mater, Cyclin B1, CDK1, OCT4 and STAT3 in good quality oocytes that stained positively for BCB (BCB+). Collectively, results provide novel information about the use of BCB screening for selecting good quality oocytes to improvein vitroembryo production in the dromedary camel.

Increased bone morphogenetic protein-6 in follicular fluid and granulosa cells may correlate with fertilization and embryo quality in humans

Bone morphogenetic protein-6 (BMP-6), which is a member of the transforming growth factor-β superfamily, is associated with the regulation of bone development and various physiological processes. In the present study, the expression of BMP-6 in follicular fluid and granulosa cells (GCs) from pregnant and non-pregnant patients was explored. A total of 44 pregnant patients (pregnant group) and 36 non-pregnant patients (non-pregnant group) were recruited for the present study. The expression of BMP-6 was detected using western blotting and reverse transcription-quantitative polymerase chain reaction. The expression of BMP-6 was significantly higher at the protein level (P<0.01) in follicular fluid obtained from the pregnant group compared with that from the non-pregnant group. The mRNA and protein expression of BMP-6 in GCs were significantly upregulated in the pregnant group compared with the non-pregnant group (both P<0.01). These results suggest that high expression of BMP-6 in pregnant women may be a novel biomarker for the fertility process.

Use of Bone Morphogenetic Protein 15 Polymorphisms to Predict Ovarian Stimulation Outcomes in Infertile Brazilian Women

AIMS

Polymorphisms in the gene encoding bone morphogenetic protein 15 (BMP15) can result in inhibited secretion or lowered bioactivity of the BMP15 protein. BMP15 levels are associated with follicle-stimulating hormone receptor (FSHR) action on granulosa cells, wherein FSHR increases the sensitivity of ovarian follicles to follicle-stimulating hormone (FSH). In this study we evaluated the BMP15 polymorphisms A905 > G/rs3897937, C901 > T/rs17003221, and C-9 > G/rs3810682 in infertile Brazilian women in terms of anti-Mullerian hormone (AMH), FSH, and estradiol serum levels, as well as controlled ovarian hyperstimulation response and assisted reproduction outcomes.

METHODS

A cross-sectional study comprising 186 infertile women who underwent the first cycle of high complexity assisted reproduction treatment was conducted using the TaqMan assay for quantitative polymerase chain reaction genotyping. Serum AMH, FSH, and estradiol levels were measured by enzyme-linked immunosorbent assay.

RESULTS

For C901 > T (rs17003221) carriers, there was a statistically significant difference among carriers of a polymorphic BMP15 genotype (TT) and the estradiol concentration. These women had higher estradiol levels than women who had homozygous wild type or heterozygous genotypes. There was also a positive correlation between serum AMH and the C-9 > G (rs3810682) polymorphism, wherein women carrying both polymorphic alleles (homozygous, GG) had higher average AMH levels than heterozygous women. However, none of the three polymorphisms studied showed a statistically significant correlation with assisted reproduction outcome.

DISCUSSION

Oocytes are known to secrete factors that regulate follicular development and oocyte maturation. Abnormal expression of these factors may thus be involved in follicular development disorders. A recent study highlighted the importance of BMP15 in regulating ovulation rates in sheep and that heterozygous deletions in the -9C > G polymorphism reduced BMP15 concentrations, increased granulosa cell FHSR mRNA levels, elevated estrogen secretion, and activated production of stem cell factors. In this study we found that BMP15 polymorphisms affected estrogen and AMH levels.

CONCLUSION

BMP15 polymorphisms are not correlated with ovarian stimulation and assisted reproduction outcomes in infertile Brazilian women.

Effect of a high fat diet on ovary morphology, in vitro development, in vitro fertilisation rate and oocyte quality in mice

INTRODUCTION

The aim of this study was to determine the effect of a high-fat diet (HFD) on oocyte maturation and quality in a mouse model.

METHODS

Female BALB/c mice were allocated to one of the following groups: (a) control group (n = 40), which received a controlled diet; or (b) HFD group (n = 40), which received an HFD for 12 weeks. Sections of the ovary were examined histologically. The number of follicles and corpora lutea were counted. In vitro maturation and in vitro fertilisation (IVF) were assessed in germinal vesicle (GV) and metaphase II (MII) oocytes, respectively. The expression of bone morphogenetic protein 15 (BMP15) and leptin receptor genes in GV and MII oocytes was evaluated using reverse transcription real-time polymerase chain reactions.

RESULTS

In the HFD group, there was a decreased number of primordial and Graafian follicles, as well as corpora lutea (p < 0.05). The rate of oocyte development to the MII stage was also reduced (p < 0.001). Cumulus expansion was observed more frequently in the control group than the HFD group (p < 0.05). The IVF rate in the HFD group was lower than that in the control group (p < 0.05). In the HFD group, BMP15 and leptin receptor genes were upregulated in the GV stage (p > 0.05) and MII stage (p < 0.05), compared to the control group.

CONCLUSION

An HFD reduces folliculogenesis in the primordial and Graafian stages, in vitro maturation and in vitro fertilisation rates, as well as oocyte quality in mice.

Oocyte-somatic cell interactions in the human ovary-novel role of bone morphogenetic proteins and growth differentiation factors

BACKGROUND

Initially identified for their capability to induce heterotopic bone formation, bone morphogenetic proteins (BMPs) are multifunctional growth factors that belong to the transforming growth factor β superfamily. Using cellular and molecular genetic approaches, recent studies have implicated intra-ovarian BMPs as potent regulators of ovarian follicular function. The bi-directional communication of oocytes and the surrounding somatic cells is mandatory for normal follicle development and oocyte maturation. This review summarizes the current knowledge on the physiological role and molecular determinants of these ovarian regulatory factors within the human germline-somatic regulatory loop.

OBJECTIVE AND RATIONALE

The regulation of ovarian function remains poorly characterized in humans because, while the fundamental process of follicular development and oocyte maturation is highly similar across species, most information on the regulation of ovarian function is obtained from studies using rodent models. Thus, this review focuses on the studies that used human biological materials to gain knowledge about human ovarian biology and disorders and to develop strategies for preventing, diagnosing and treating these abnormalities.

SEARCH METHODS

Relevant English-language publications describing the roles of BMPs or growth differentiation factors (GDFs) in human ovarian biology and phenotypes were comprehensively searched using PubMed and the Google Scholar database. The publications included those published since the initial identification of BMPs in the mammalian ovary in 1999 through July 2016.

OUTCOMES

Studies using human biological materials have revealed the expression of BMPs, GDFs and their putative receptors as well as their molecular signaling in the fundamental cells (oocyte, cumulus/granulosa cells (GCs) and theca/stroma cells) of the ovarian follicles throughout follicle development. With the availability of recombinant human BMPs/GDFs and the development of immortalized human cell lines, functional studies have demonstrated the physiological role of intra-ovarian BMPs/GDFs in all aspects of ovarian functions, from follicle development to steroidogenesis, cell–cell communication, oocyte maturation, ovulation and luteal function. Furthermore, there is crosstalk between these potent ovarian regulators and the endocrine signaling system. Dysregulation or naturally occurring mutations within the BMP system may lead to several female reproductive diseases. The latest development of recombinant BMPs, synthetic BMP inhibitors, gene therapy and tools for BMP-ligand sequestration has made the BMP pathway a potential therapeutic target in certain human fertility disorders; however, further clinical trials are needed. Recent studies have indicated that GDF8 is an intra-ovarian factor that may play a novel role in regulating ovarian functions in the human ovary.

WIDER IMPLICATIONS

Intra-ovarian BMPs/GDFs are critical regulators of folliculogenesis and human ovarian functions. Any dysregulation or variations in these ligands or their receptors may affect the related intracellular signaling and influence ovarian functions, which accounts for several reproductive pathologies and infertility. Understanding the normal and pathological roles of intra-ovarian BMPs/GDFs, especially as related to GC functions and follicular fluid levels, will inform innovative approaches to fertility regulation and improve the diagnosis and treatment of ovarian disorders.

Oocyte-dependent activation of MTOR in cumulus cells controls the development and survival of cumulus-oocyte complexes

Communication between oocytes and their companion somatic cells promotes the healthy development of ovarian follicles, which is crucial for producing oocytes that can be fertilized and are competent to support embryogenesis. However, how oocyte-derived signaling regulates these essential processes remains largely undefined. Here, we demonstrate that oocyte-derived paracrine factors, particularly GDF9 and GDF9-BMP15 heterodimer, promote the development and survival of cumulus-cell-oocyte complexes (COCs), partly by suppressing the expression of Ddit4l, a negative regulator of MTOR, and enabling the activation of MTOR signaling in cumulus cells. Cumulus cells expressed less Ddit4l mRNA and protein than mural granulosa cells, which is in striking contrast to the expression of phosphorylated RPS6 (a major downstream effector of MTOR). Knockdown of Ddit4l activated MTOR signaling in cumulus cells, whereas inhibition of MTOR in COCs compromised oocyte developmental competence and cumulus cell survival, with the latter likely to be attributable to specific changes in a subset of transcripts in the transcriptome of COCs. Therefore, oocyte suppression of Ddit4l expression allows for MTOR activation in cumulus cells, and this oocyte-dependent activation of MTOR signaling in cumulus cells controls the development and survival of COCs.

Dysregulation of granulosal bone morphogenetic protein receptor 1B density is associated with reduced ovarian reserve and the age-related decline in human fertility

Reproductive ageing is linked to the depletion of ovarian primordial follicles, which causes an irreversible change to ovarian cellular function and the capacity to reproduce. The current study aimed to profile the expression of bone morphogenetic protein receptor, (BMPR1B) in 53 IVF patients exhibiting different degrees of primordial follicle depletion. The granulosa cell receptor density was measured in 403 follicles via flow cytometry. A decline in BMPR1B density occurred at the time of dominant follicle selection and during the terminal stage of folliculogenesis in the 23-30 y good ovarian reserve patients. The 40+ y poor ovarian reserve patients experienced a reversal of this pattern. The results demonstrate an association between age-induced depletion of the ovarian reserve and BMPR1B receptor density at the two critical time points of dominant follicle selection and pre-ovulatory follicle maturation. Dysregulation of BMP receptor signalling may inhibit the normal steroidogenic differentiation required for maturation in older patients.

An essential role for the intra-oocyte MAPK activity in the NSN-to-SN transition of germinal vesicle chromatin configuration in porcine oocytes

The mechanisms for the transition from non-surrounded nucleolus (NSN) to surrounded nucleolus (SN) chromatin configuration during oocyte growth/maturation are unclear. By manipulating enzyme activities and measuring important molecules using small-follicle pig oocytes with a high proportion of NSN configuration and an extended germinal vesicle stage in vitro, this study has the first time up-to-date established the essential role for intra-oocyte mitogen-activated protein kinase (MAPK) in the NSN-to-SN transition. Within the oocyte in 1–2 mm follicles, a cAMP decline activates MAPK, which prevents the NSN-to-SN transition by activating nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) while inhibiting histone deacetylase (HDAC). In cumulus cells of 1–2 mm follicles, a lower level of estradiol and oocyte-derived paracrine factor (ODPF) reduces natriuretic peptide receptor 2 (NPR2) while enhancing FSH and cAMP actions. FSH elevates cAMP levels, which decreases NPR2 while activating MAPK. MAPK closes the gap junctions, which, together with the NPR2 decrease, reduces cyclic guanosine monophosphate (cGMP) delivery leading to the cAMP decline within oocytes. In 3–6 mm follicles, a higher level of estradiol and ODPF and a FSH shortage initiate a reversion of the above events leading to MAPK inactivation and NSN-to-SN transition within oocytes.

Proteomic analysis of preovulatory follicular fluid reveals differentially abundant proteins in less fertile dairy cows

The follicular fluid (FF) proteome can provide an indication of follicular quality. High-yielding dairy cows suffer from low fertility, which could be related to follicular function. However, the proteome of preovulatory follicles has never been described in cows. Our objectives were to: 1) define the bovine preovulatory FF proteome, and 2) examine differentially abundant proteins in FF of controls (CTL, n=10) and less fertile cows (LFC; failed to conceive following ≥6 inseminations, n=8). Follicles ≥7mm in diameter were aspirated in vivo, and estradiol (E2) and progesterone (P4) were examined. The FF from 10 preovulatory follicles (E2/P4>1) was analyzed; E2 was higher and follicle diameter tended to be larger in LFC. As aspirations were conducted at a fixed time, this suggests accelerated follicular growth in LFC. The 219 identified and quantified proteins consisted mainly of binding proteins, proteases, receptor ligands, enzymes and transporters. Differential abundance of 8 relevant proteins was found in LFC compared to CTL: SERPINA1, TIMP2, ITIH1, HSPG2, C8A, COL1A2, F2, and IL1RAP. These proteins could influence follicular function-e.g., decreased SERPINA1 may be related to accelerated follicular growth-and therefore, further examination of their roles in the etiology of LFC is warranted.

SIGNIFICANCE

High yielding dairy cows suffer from infertility that leads to major economic losses worldwide. In Israel, about 30% of dairy cows fail to conceive following ≥4 inseminations. The etiology of this low fertility is multifactorial and remains a serious challenge. Follicular fluid proteome can provide indication to follicular quality, yet the proteome of pre-ovulatory follicles has not been described in cows. This work examined the differential abundance of proteins in less fertile dairy cows compared to controls, and found 8 relevant novel proteins that could influence follicular function. The role of these proteins in the etiology of less fertile cows should be further examined.

Insights into female germ cell biology: from in vivo development to in vitro derivations

Understanding the mechanisms of human germ cell biology is important for developing infertility treatments. However, little is known about the mechanisms that regulate human gametogenesis due to the difficulties in collecting samples, especially germ cells during fetal development. In contrast to the mitotic arrest of spermatogonia stem cells in the fetal testis, female germ cells proceed into meiosis and began folliculogenesis in fetal ovaries. Regulations of these developmental events, including the initiation of meiosis and the endowment of primordial follicles, remain an enigma. Studying the molecular mechanisms of female germ cell biology in the human ovary has been mostly limited to spatiotemporal characterizations of genes or proteins. Recent efforts in utilizing in vitro differentiation system of stem cells to derive germ cells have allowed researchers to begin studying molecular mechanisms during human germ cell development. Meanwhile, the possibility of isolating female germline stem cells in adult ovaries also excites researchers and generates many debates. This review will mainly focus on presenting and discussing recent in vivo and in vitro studies on female germ cell biology in human. The topics will highlight the progress made in understanding the three main stages of germ cell developments: namely, primordial germ cell formation, meiotic initiation, and folliculogenesis.

Effect of Anti-Müllerian hormone (AMH) and bone morphogenetic protein 15 (BMP-15) on steroidogenesis in primary-cultured human luteinizing granulosa cells through Smad5 signalling

PURPOSE

To determine if there is any effect of AMH and BMP-15 on estradiol and progesterone production from primary-cultured human luteinizing granulosa cells, to delineate what is the effect of FSH on their actions and which are the possible mechanisms involved.

METHODS

Luteinizing granulosa cells (GCs), obtained from follicular fluid of 30 women undergoing in vitro fertilization, were cultured, after a short 24-h preincubation period, in serum-free medium for 24 or/and 48 h in the presence/absence of various concentrations of AMH, BMP-15 and FSH alone or in combinations. Estradiol and progesterone production, SMAD5 phosphorylation and StAR expression were studied in parallel. Steroids were measured in culture-supernatant using enzyme-immunoassays, while Smad5-signaling pathway activation and StAR protein expression were assessed immunocytochemically.

RESULT(S)

We found that the treatment of AMH in GCs for 24/48 h attenuated FSH-induced estradiol production (p < 0.001), had no effect on basal estradiol levels, decreased basal progesterone production (p < 0.001) and FSH-induced StAR expression (p < 0.001). On the other hand, BMP-15 decreased basal estradiol levels (p < 0.001) and attenuated FSH-induced estradiol production (p < 0.001). Furthermore, BMP-15 reduced progesterone basal secretion (p < 0.001), an effect that was partially reversed by FSH (p < 0.01), probably via increasing StAR expression (p < 0.001). FSH-induced StAR expression was also attenuated by BMP-15 (p < 0.001). FSH, AMH and BMP-15 activated Smad-signaling pathway, as confirmed by the increase of phospo-Smad5 protein levels (p < 0.001 compared to control).

CONCLUSION(S)

AMH and BMP-15 by interacting with FSH affect the production of estradiol and progesterone from cultured luteinizing-granulosa cells possibly via Smad5-protein phosphorylation.

The bone morphogenetic protein system and the regulation of ovarian follicle development in mammals

The bone morphogenetic protein (BMP) family consists of several growth factor proteins that belong to the transforming growth factor-β (TGF-β) superfamily. BMPs bind to type I and type II serine-threonine kinase receptors, and transduce signals through the Smad signalling pathway. BMPs have been identified in mammalian ovaries, and functional studies have shown that they are involved in the regulation of oogenesis and folliculogenesis. This review summarizes the role of the BMP system during formation, growth and maturation of ovarian follicles in mammals.