Extracellular microRNAs in follicular fluid and their potential association with oocyte fertilization and embryo quality: an exploratory study

DBP Exposure Affects Oocyte Fertilization Via Extracellular Vesicles-Derived miR-116-5p in Ovarian Granulosa Cells Through Downregulating FOXO3a Expression

Mono-butyl phthalate (MBP), the metabolite of dibutyl phthalate (DBP), is the most abundant phthalate metabolite found in Chinese women. Extracellular vesicles (EVs) are nanoscale lipid bilayer particles produced by extensive kinds of cells, serving a key role in intercellular communication. Extracellular vesicle miRNAs (EV-miRNAs) in follicular fluid (FF) have been evidenced to be associated with female reproductive health. The objective of this study was to investigate the associations of EV-miRNAs expressed profile with DBP exposure in FF of female participants and expose its potential mechanism in impaired oocyte development. Based on participants' FF MBP concentrations and fertilization status, we compared the miRNA expression between the FF-EVs of group A (high DBP exposure and impaired fertilization) and group B (low DBP exposure and normal fertilization). Compared with group B, miR-1246, miR-3679-5p, miR-423-5p, miR-5585-3p, miR-116-5p, miR-172-5p were upregulated, while miR-34b-3p was downregulated in group A. Target genes of the differently expressed miRNAs were predicted, and the functional analysis was performed. Furthermore, we exposed human ovarian granulosa tumor cell line (KGN) to MBP (4ug/L) to isolate the EVs from the culture medium and validated the expression levels of different miRNAs. We found that MBP exposure was significantly associated with increased levels of miR-116-5p (P = 0.01). In addition, we demonstrated that the most different miRNA, miR-116-5p regulated oocyte fertilization by inhibiting FOXO3a. Our findings suggested that EV-miRNAs in the FF might mediate MBP toxicity in oocytes.

Oocyte Maturation and miRNAs: Studying a Complicate Interaction to Reveal Possible Biomarkers for Female Infertility

Cellular metabolism, apoptosis, fertilization, and proliferation of granulosa cells belong to a battery of processes where microRNAs can be detected and associated with infertility. The aim of the present review is to focus on mammalian oocyte maturation events and the association between oocyte growth and miRNA expression. PubMed/Medline, Google Scholar and Scopus databases were searched, and 33 studies were included. Regarding the correlation among miRNA expression and the regulation of granulosa cells and cumulus cells, the most important miRNAs were let-7b, let-7c and miR-21. Additionally, the loss of Dicer, an enzyme involved in miRNA biogenesis, is probably a crucial factor in oogenesis, oocyte maturation and embryogenesis. Furthermore, miRNAs interfere with different cellular mechanisms like apoptosis, steroidogenesis, genome integrity, angiogenesis, antioxidative response and, consequently, oocyte maturation. Hence, it is of major importance to clarify the role and mechanism of each miRNA as understanding its action may develop new tools and establish new diagnostic and treatment approaches for infertility and ovarian disorders.

An Update on Physiopathological Roles of Akt in the ReprodAKTive Mammalian Ovary

The phosphoinositide 3-kinase (PI3K)/Akt pathway is a key signaling cascade responsible for the regulation of cell survival, proliferation, and metabolism in the ovarian microenvironment. The optimal finetuning of this pathway is essential for physiological processes concerning oogenesis, folliculogenesis, oocyte maturation, and embryo development. The dysregulation of PI3K/Akt can impair molecular and structural mechanisms that will lead to follicle atresia, or the inability of embryos to reach later stages of development. Due to its pivotal role in the control of cell proliferation, apoptosis, and survival mechanisms, the dysregulation of this molecular pathway can trigger the onset of pathological conditions. Among these, we will focus on diseases that can harm female fertility, such as polycystic ovary syndrome and premature ovarian failure, or women's general health, such as ovarian cancer. In this review, we report the functions of the PI3K/Akt pathway in both its physiological and pathological roles, and we address the existing application of inhibitors and activators for the balancing of the molecular cascade in ovarian pathological environments.

Use of assisted reproductive technologies (ARTs) to shorten the generational interval in ruminants: current status and perspectives

The challenges posed by climate change and increasing world population are stimulating renewed efforts for improving the sustainability of animal production. To meet such challenges, the contribution of genomic selection approaches, in combination with assisted reproductive technologies (ARTs), to spreading and preserving animal genetics is essential. The largest increase in genetic gain can be achieved by shortening the generation interval. This review provides an overview of the current status and progress of advanced ARTs that could be applied to reduce the generation time in both female and male of domestic ruminants. In females, the use of juvenile in vitro embryo transfer (JIVET) enables to generate offspring after the transfer of in vitro produced embryos derived from oocytes of prepubertal genetically superior donors reducing the generational interval and acceleration genetic gain. The current challenge is increasing in vitro embryo production (IVEP) from prepubertal derived oocytes which is still low and variable. The two main factors limiting IVEP success are the intrinsic quality of prepubertal oocytes and the culture systems for in vitro maturation (IVM). In males, advancements in ARTs are providing new strategies to in vitro propagate spermatogonia and differentiate them into mature sperm or even to recapitulate the whole process of spermatogenesis from embryonic stem cells. Moreover, the successful use of immature cells, such as round spermatids, for intracytoplasmic injection (ROSI) and IVEP could allow to complete the entire process in few months. However, these approaches have been successfully applied to human and mouse whereas only a few studies have been published in ruminants and results are still controversial. This is also dependent on the efficiency of ROSI that is limited by the current isolation and selection protocols of round spermatids. In conclusion, the current efforts for improving these reproductive methodologies could lead toward a significant reduction of the generational interval in livestock animals that could have a considerable impact on agriculture sustainability.

Identification of Differentially Expressed mRNAs and miRNAs and Related Regulatory Networks in Cumulus Oophorus Complexes Associated with Fertilization

Cumulus oophorus complexes (COCs) are the first extracellular barriers that sperm must pass through to fuse with oocytes, which have an important role in oocyte maturation and fertilization. However, little is known about the molecular mechanisms of COCs involved in fertilization. In this study, COCs were collected and then randomly divided into a test group that interacted with sperm and a control group that did not interact with sperm. Then, the total RNA was extracted; RNA transcriptome and small RNA libraries were prepared, sequenced, and analyzed. The results showed that 1283 differentially expressed genes (DEGs), including 560 upregulated and 723 downregulated genes. In addition, 57 differentially expressed miRNAs (DEMIs) with 35 upregulated and 22 downregulated were also detected. After the RNA-seq results were verified by RT-qPCR, 86 effective DEGs and 40 DEMIs were finally screened and a DEMI-DEG regulatory network was constructed. From this, the top ten hub target genes were HNF4A, SPN, WSCD1, TMEM239, SLC2A4, E2F2, SIAH3, ADORA3, PIK3R2, and GDNF, and they were all downregulated. The top ten hub DEMIs were miR-6876-5p, miR-877-3p, miR-6818-5p, miR-4690-3p, miR-6789-3p, miR-6837-5p, miR-6861-5p, miR-4421, miR-6501-5p, and miR-6875-3p, all of which were upregulated. The KEGG signaling pathway enrichment analysis showed that the effective DEGs were significantly enriched in the calcium, AMPK, and phospholipase D signaling pathways. Our study identified several DEGs and DEMIs and potential miRNA-mRNA regulatory pathways in COCs and these may contribute to fertilization. This study may provide novel insights into potential biomarkers for fertilization failure.

How should the best human embryo in vitro be? Current and future challenges for embryo selection

In-vitro fertilization (IVF) aims at overcoming the causes of infertility and lead to a healthy live birth. To maximize IVF efficiency, it is critical to identify and transfer the most competent embryo within a cohort produced by a couple during a cycle. Conventional static embryo morphological assessment involves sequential observations under a light microscope at specific timepoints. The introduction of time-lapse technology enhanced morphological evaluation via the continuous monitoring of embryo preimplantation in vitro development, thereby unveiling features otherwise undetectable via multiple static assessments. Although an association exists, blastocyst morphology poorly predicts chromosomal competence. In fact, the only reliable approach currently available to diagnose the embryonic karyotype is trophectoderm biopsy and comprehensive chromosome testing to assess non-mosaic aneuploidies, namely preimplantation genetic testing for aneuploidies (PGT-A). Lately, the focus is shifting towards the fine-tuning of non-invasive technologies, such as "omic" analyses of waste products of IVF (e.g., spent culture media) and/or artificial intelligence-powered morphologic/morphodynamic evaluations. This review summarizes the main tools currently available to assess (or predict) embryo developmental, chromosomal, and reproductive competence, their strengths, the limitations, and the most probable future challenges.

Biochemical profiling of the follicular environment to predict oocyte competence in cattle

To identify markers of oocyte competence, we compared the biochemical characteristics of fluid and cells from follicles containing oocytes with different capacities to form an embryo. Follicles (5-6 mm) were dissected, and follicular fluid (FF), granulosa cells (GC), cumulus cells (CC) from immature and mature cumulus-oocyte-complexes (COC) were individually collected. The oocytes were matured, fertilized, and cultured individually until day 8 (D8) of development. On D8, the samples were grouped according to embryo production into those that gave rise to blastocysts (EMB) and those that did not reach the blastocyst stage (NEMB). In CCs from immature and mature COCs and GCs, expression of CASP3, SERPINE2, VCAN, LUM, FSHR, EGFR, PGR, and GHR genes was quantified. Cell-free DNA (cfDNA), progesterone, and estradiol concentrations in the FF were determined. Data were analyzed by Mann-Whitney U test (GraphPad Prism 9). GHR was highly expressed in immature CCs from the EMB group, whereas CASP3 was highly expressed in mature CCs from the NEMB group (P<0.05). During maturation, the expression of CASP3 and GHR genes increased only in the NEMB group. ART2 cfDNA was highly detected in FF of the NEMB compared to the EMB group. Progesterone concentration was similar between the groups, whereas estradiol concentration was higher (P<0.05) in the EMB than in the NEMB group. It was concluded that a higher level of GHR transcripts in immature CCs, lower CASP3 expression in CCs from matured COCs, lower levels of ART2, and higher estradiol concentrations in FF may indicate oocytes with greater potential for development.

microRNAs associated with the quality of follicular fluids affect oocyte and early embryonic development

Purpose

Oocyte and embryo quality differs significantly among individuals. Follicular fluid (FF) is a solo environment of oocyte maturation and may flux into the oviduct. Supplementation of in vitro maturation (IVM) and culture (IVC) medium with extracellular vesicles of FFs supports oocyte maturation and embryonic development. We addressed a hypothesis that miRNA profiles in FFs are crucial background of oocyte maturation and embryonic development.

Methods

FFs were collected from the ovaries of individual cows, and the FFs were classified into Good or Poor FF based on the developmental rate to the blastocyst stage of enclosed oocytes. miRNAs associated with the Good FFs were explored using small RNA sequencing. In addition, FFs were classified using the concentration of Good-FF-associated miRNAs. These classified FFs or miRNA were added to the IVM or IVC mediums.

Results

Supplementation of IVM and IVC medium with Good FF improved embryonic development. Good FFs contained miR-151-3p and miR-425-5p at a high concentration compared with those in Poor FFs. FFs selected by the concentration of miR-151-3p and miR-425-5p improved oocyte maturation and embryonic development. Supplementation of IVM or IVC medium with either miR-151-3p or miR-425-5p improved embryonic development to the blastocyst stage.

Conclusion

miRNAs were associated with the Good FFs determined oocyte maturation and embryonic development.

Influence of the starting day of luteal phase stimulation on double stimulation cycles

Background

Double ovarian stimulation is one of the most used strategies in poor-prognosis patients. There is a high heterogeneity between the studies regarding the execution of this stimulation protocol. The aim of this study was to investigate whether the day on which luteal phase stimulation begins after the first oocyte retrieval affects ovarian response in DuoStim cycles.

Methods

This observational and retrospective study included 541 DuoStim cycles between January 2018 and December 2021 in a private fertility clinic. Patients were assigned to 4 groups according to the timing of the onset of luteal phase stimulation after oocyte retrieval (0-2^nd day, 3^rd day, 4^th day and 5^th-6^th day). The primary outcome was the number of oocytes retrieved in the luteal phase in each group.

Results

No differences were found between groups in the number of oocytes collected (5.12 ± 3.56 vs. 5.39 ± 3.74 vs. 5.61 ± 3.94 vs. 5.89 ± 3.92; p=0,6), MII or number of follicles. An increase in the duration of stimulation was found when stimulation started on the 4^th day (10.42 ± 2.31 vs. 10.68 ± 2.37 vs. 11.27 ± 2.40 vs. 10.65 ± 2.37 days, p=0,033). A lower number of fertilized oocytes was observed when stimulation began before the fourth day (3.36 ± 2.80 vs. 3.95 ± 2.53 vs. 4.03 ± 2.73 vs. 4.48 ± 3.11; p=0,036). The number of blastocysts was higher when the stimulation started 5-6 days after retrieval (1.82 ± 1.74 vs. 2.13 ± 1.61 vs. 2.33 ± 2.06 vs. 2.91 ± 2.39; p= 0,030).

Discussion

The number of oocytes retrieved does not differ depending on the day that stimulation begins. However, oocytes competence in terms of fertilized oocytes and blastulation, appears to be lower when the second stimulation starts before the fourth day after oocyte retrieval.

From in vivo to in vitro: exploring the key molecular and cellular aspects of human female gametogenesis

Human oogenesis is a highly complex and not yet fully understood process due to ethical and technological barriers that limit studies in the field. In this context, replicating female gametogenesis in vitro would not only provide a solution for some infertility problems, but also be an excellent study model to better understand the biological mechanisms that determine the formation of the female germline. In this review, we explore the main cellular and molecular aspects involved in human oogenesis and folliculogenesis in vivo, from the specification of primordial germ cells (PGCs) to the formation of the mature oocyte. We also sought to describe the important bidirectional relationship between the germ cell and the follicular somatic cells. Finally, we address the main advances and different methodologies used in the search for obtaining cells of the female germline in vitro.

MicroRNAs, small regulatory elements with significant effects on human implantation: a review

Embryo implantation is a critical process for achieving a successful pregnancy and live birth. The proper implantation must have a synchronized interaction between blastocyst and a receptive endometrium. Many genes are involved in the modulation of precise molecular events during implantation. MicroRNAs (miRNAs) have been extensively reported as gene regulatory molecules on post-transcriptional levels involved in various biological processes such as gametogenesis, embryogenesis, and the quality of sperm, oocyte, and embryos. A plethora of evidence has demonstrated critical roles for miRNAs in regulating genes involved in the implantation process; hence, dysregulation of miRNAs could be associated with significant impairments in implantation, such as recurrent implantation failure. In addition to the indispensable role of miRNAs in the intracellular control of gene expression, they can also be secreted into extracellular fluid and circulation. Therefore, miRNAs in body fluids and blood may be exploited as non-invasive diagnostic biomarkers for different pathological and physiological conditions. Recently, several studies have focused on the discovery of miRNAs function in the implantation process by appraising miRNAs and their target genes in human embryos, endometrial tissue, and cell culture models. Moreover, it was revealed that there could be a significant association between endometrial receptivity or implantation status and the expression of miRNAs in human body fluids, reinforcing their role as non-invasive biomarkers. In the current work, we reviewed the studies concerning the role of intracellular and extracellular miRNAs in human implantation and the influence of their dysregulation on implantation disorders.

Non-Coding RNAs as Biomarkers for Embryo Quality and Pregnancy Outcomes: A Systematic Review and Meta-Analysis

Despite advances in in vitro fertilization (IVF), there is still a lack of non-invasive and reliable biomarkers for selecting embryos with the highest developmental and implantation potential. Recently, small non-coding RNAs (sncRNAs) have been identified in biological fluids, and extracellular sncRNAs are explored as diagnostic biomarkers in the prediction of IVF outcomes. To determine the predictive role of sncRNAs in embryo quality and IVF outcomes, a systematic review and meta-analysis was performed. Articles were retrieved from PubMed, EMBASE, and Web of Science from 1990 to 31 July 2022. Eighteen studies that met the selection criteria were analyzed. In total, 22 and 47 different sncRNAs were found to be dysregulated in follicular fluid (FF) and embryo spent culture medium (SCM), respectively. MiR-663b, miR-454 and miR-320a in FF and miR-20a in SCM showed consistent dysregulation in two different studies. The meta-analysis indicated the potential predictive performance of sncRNAs as non-invasive biomarkers, with a pooled area under curve (AUC) value of 0.81 (95% CI 0.78, 0.844), a sensitivity of 0.79 (95% CI 0.72, 0.85), a specificity of 0.67 (95% CI 0.52, 0.79) and a diagnostic odds ratio (DOR) of 8 (95% CI 5, 12). Significant heterogeneity was identified among studies in sensitivity (I2  =  46.11%) and specificity (I2  =  89.73%). This study demonstrates that sncRNAs may distinguish embryos with higher developmental and implantation potentials. They can be promising non-invasive biomarkers for embryo selection in ART. However, the significant heterogeneity among studies highlights the demand for prospective multicenter studies with optimized methods and adequate sample sizes in the future.

Recombinant human chorionic gonadotropin and gonadotropin-releasing hormone agonist differently affect the profile of extracellular vesicle microRNAs in human follicular fluid

PURPOSE

To compare the expression profile of extracellular vesicle microRNAs (EV-miRNAs) derived from follicular fluid after a trigger with recombinant human chorionic gonadotropin (r-hCG) or with a gonadotropin-releasing hormone GnRH agonist (GnRH-a) for final oocyte maturation.

METHODS

A retrospective analysis of a prospective cohort. Women undergoing in vitro fertilization at a tertiary university-affiliated hospital were recruited between 2014 and 2016. EV-miRNAs were extracted from the follicular fluid of a single follicle, and their expression was assessed using TaqMan Open Array®. Genes regulated by EV-miRNAs were analyzed using miRWalk2.0 Targetscan database, DAVID Bioinformatics Resources, Kyoto-Encyclopedia of Genes and Genomes (KEGG), and Gene Ontology (GO).

RESULTS

Eighty-two women were included in the r-hCG trigger group and 9 in the GnRH-a group. Of 754 EV-miRNAs screened, 135 were detected in at least 50% of the samples and expressed in both groups and were further analyzed. After adjusting for multiple testing, 41 EV-miRNAs whose expression levels significantly differed between the two trigger groups were identified. Bioinformatics analysis of the genes regulated by these EV-miRNAs showed distinct pathways between the two triggers, including TGF-beta signaling, cell cycle, and Wnt signaling pathways. Most of these pathways regulate cascades associated with apoptosis, embryo development, implantation, decidualization, and placental development.

CONCLUSIONS

Trigger with GnRH-a or r-hCG leads to distinct EV-miRNAs expression profiles and to downstream biological effects in ovarian follicles. These findings may provide an insight for the increased apoptosis and the lower implantation rates following GnRH-a trigger vs. r-hCG in cases lacking intensive luteal phase support.

Isolation of Extracellular Vesicles from Human Follicular Fluid: Size-Exclusion Chromatography versus Ultracentrifugation

Follicular fluid (FF) is the microenvironment where a growing oocyte develops. Intrafollicular communication ensures oocyte competence and is carried out through paracrine signaling, the exchange of molecules via gap junctions, and the trafficking of extracellular vesicles (EVs). The study of FF-derived EVs is important for both translational and fundamental research in the female reproductive field. This study aimed to compare the efficacy and purity of two EV isolation methods: size-exclusion chromatography (SEC) and ultracentrifugation (UC). EVs isolated using SEC and UC were compared regarding their size and concentration using dynamic light scattering (DLS) and nanoparticle tracking analysis (NTA); protein contamination was assessed with microBCA; specific EV markers were detected with Western blot, and EV morphology was studied with transmission electron microscopy (TEM). Our results show that although both techniques isolated small EVs, a significantly increased yield in particle number was clear with UC compared with SEC. On the other hand, SEC generated purer EVs with fewer protein contaminants and aggregates. In conclusion, the selection of the most suited approach to isolate EVs must be conducted considering the degree of recovery, purity, and downstream application of the isolated EVs.

Extracellular vesicles-encapsulated microRNA in mammalian reproduction: A review

Extracellular vesicles (EVs) are nanoscale cell-derived lipid vesicles that participate in cell-cell communication by delivering cargo, including mRNAs, proteins and non-coding RNAs, to recipient cells. MicroRNA (miRNA), a non-coding RNA typically 22 nucleotides long, is crucial for nearly all developmental and pathophysiological processes in mammals by regulating recipient cells gene expression. Infertility is a worldwide health issue that affects 10-15% of couples during their reproductive years. Although assisted reproductive technology (ART) gives infertility couples hope, the failure of ART is mainly unknown. It is well accepted that EVs-encapsulated miRNAs have a role in different reproductive processes, implying that these EVs-encapsulated miRNAs could optimize ART, improve reproductive rate, and treat infertility. As a result, in this review, we describe the present understanding of EVs-encapsulated miRNAs in reproduction regulation.

Inhibition of oocyte maturation by follicular extracellular vesicles of non-hyperandrogenic PCOS patients requiring IVF

CONTEXT

Polycystic ovarian syndrome (PCOS) is one of the most common diseases that contribute to subfertility. Recent evidence showed that oocytes of women with PCOS matured in vitro away from the follicular fluid presented better potentials, whereas the reason remained unclear.

OBJECTIVE

To investigate whether follicular extracellular vesicles (EVs) of PCOS patients interfere with the quality of oocytes.

METHODS

Follicular EVs of women with PCOS (PCOS-EVs) and control women (CTRL-EVs) were isolated and determined using western blotting, nanoparticle tracking analysis, and transmission electron microscopy. The two types of EVs were co-cultured with murine germinal vesicle oocytes, respectively. Fluorescence labeled EVs were used to visualize internalization by oocytes. After co-culture, oocyte maturation rates were calculated. Mitochondria distribution and reactive oxygen species (ROS) level were detected in the different groups. Spindle morphology was evaluated using immunofluorescence. Moreover, the expression of catalase (CAT), glutathione synthetase (GSS), and superoxide dismutase (SOD) was determined in the oocytes.

RESULTS

Both PCOS-EVs and CTRL-EVs are bilayered vesicles, approximately 100-150 nm in size, and enriched in EV-associating protein markers. EVs were internalized by oocytes within one hour. Oocyte maturation rate decreased significantly in the PCOS-EV group compared with the CTRL-EV group; whereas the abnormal mitochondria distribution rate and abnormal spindle rate were significantly increased in the PCOS-EV group. Moreover, PCOS-EVs increased the ROS level and the expression of CAT, GSS, and SOD in the oocytes.

CONCLUSIONS

PCOS-EVs interfered with oocyte mitochondria and spindles and inhibited oocyte maturation. Moreover, oxidative stress induced by PCOS-EVs might be a potential cause.

hsa-miR-320a-3p and hsa-miR-483-5p levels in human granulosa cells: promising bio-markers of live birth after IVF/ICSI

BACKGROUND

MicroRNAs (miRNAs) are considered potential biomarkers for various diseases. This study investigated whether hsa-miR-320a-3p and hsa-miR-483-5p levels in human ovarian granulosa cells derived from follicular fluids are associated with embryo developmental competence.

METHODS

We collected 195 granulosa cells samples and analyzed the treatment outcomes in patients undergoing in vitro fertilization (n = 147) or intracytoplasmic sperm injection (n = 48) cycles. The hsa-miR-320a-3p and hsa-miR-483-5p levels in granulosa cells were measured using quantitative reverse transcription-polymerase chain reaction.

RESULTS

Patients were subdivided into four groups according to the granulosa cells hsa-miR-320a-3p and hsa-miR-483-5p levels quartiles (Q1-Q4). Embryo developmental competence was compared using the chi-square test. Patients in Q3 were less likely to achieve a normal fertilization rate for in vitro fertilization and blastocyst formation than those in Q1 as they expressed high levels of hsa-miR-320a-3p and hsa-miR-483-5p (P < 0.05). Patients in Q3 and Q4 were less likely to achieve a good-quality embryo as they expressed high levels of hsa-miR-483-5p and hsa-miR-320a-3p (P < 0.05). The hsa-miR-320a-3p and hsa-miR-483-5p levels were not associated with clinical pregnancy. However, multiple regression analysis indicated that in Q3 and Q4 intervals had experienced a decreased chance of live birth due to high expression levels of hsa-miR-320a-3p and hsa-miR-483-5p levels. The relative hsa-miR-320a-3p expression levels in granulosa cells were weakly and positively correlated with the patient age (P = 0.0033). Moreover, both the basal follicle stimulating hormone (P = 0.0003) and ovarian stimulation protocols (P = 0.006 and P = 0.004) significantly and positively affected hsa-miR-320a-3p levels. The days of stimulation was negatively correlated with the relative hsa-miR-320a-3p expression level (P = 0.047).

CONCLUSIONS

The hsa-miR-320a-3p and hsa-miR-483-5p levels in human granulosa cells negatively correlated with the good-quality embryo rate and live birth, indicating that hsa-miR-320a-3p and hsa-miR-483-5p can be used as potential negative indicators to predict good-quality embryos and live births.

Age-associated changes in miRNA profile of bovine follicular fluid

In brief

This study shows that ageing affects miRNA profiles in follicular fluid, and an miRNA that is highly abundant in the follicular fluid of young cows supports the growth of oocytes derived from early antral follicles.

Abstract

We examined age-associated changes in miRNA profiles in the follicular fluid (FF) of cows. The role of miR-19b, which is abundant in the FF of young cows, in in vitro growth of early antral follicles (EAFs)-derived oocytes was assessed. FF was collected from the antral follicles of young (20-40 months) and aged (>120 months) cows. The miRNA profiles were similar between the FF of both age groups, whereas the abundance of some miRNAs differed between these samples. The miRNA profiles in granulosa cells (GCs) and the spent culture medium of oocyte-GC complexes (OGCs) derived from EAFs were distinct. Some miRNA groups overlapped among the GCs, culture media, and FFs. miR-19b was highly abundant in the FF of young cows, GCs, and culture medium. The supplementation of OGC culture medium with miR-19b increased the diameter, acetylation levels, and fertilisation ability of the oocytes. To assess whether miR-19b was functional in the GCs, a dual-luciferase assay, suppression of target protein, and RNA-sequencing of the GCs followed by functional annotation of the differentially expressed genes (DEGs) were conducted. Functional annotation of the DEGs suggested that miR-19b influences genes associated with FoxO signalling, endocytosis, and NR3C1 in GCs. These results suggest that in FFs, ageing affects the abundance of miRNAs that have important roles in oocyte development.

Uterine extracellular vesicles as multi-signal messengers during maternal recognition of pregnancy in the mare

In contrast to other domestic mammals, the embryo-derived signal(s) leading to maternal recognition of pregnancy (MRP) are still unknow in the mare. We hypothesize that these embryonic signals could be packed into uterine extracellular vesicles (uEVs), acting as multi-signal messengers between the conceptus and the maternal tract, and contributing to MRP. To unveil these signals, the RNA and protein cargos of uEVs isolated from uterine lavages collected from pregnant mares (P; day 10, 11, 12 and 13 after ovulation) and cyclic control mares (C; day 10 and 13 after ovulation) were analyzed. Our results showed a fine-tuned regulation of the uEV cargo (RNAs and proteins), by the day of pregnancy, the estrous cycle, and even the size of the embryo. A particular RNA pattern was identified with specific increase on P12 related to immune system and hormonal response. Besides, a set of proteins as well as RNAs was highly enriched in EVs on P12 and P13. Differential abundance of miRNAs was also identified in P13-derived uEVs. Their target genes were linked to down- or upregulated genes in the embryo and the endometrium, exposing their potential origin. Our study identified for first time specific molecules packed in uEVs, which were previously associated to MRP in the mare, and thus bringing added value to the current knowledge. Further integrative and functional analyses will help to confirm the role of these molecules in uEVs during MRP in the mare.

Small-extracellular vesicles and their microRNA cargo from porcine follicular fluids: the potential association with oocyte quality

Background

Ovarian follicular fluids (FFs) contain several kinds of regulatory factors that maintain a suitable microenvironment for oocyte development. Extracellular vesicles (EVs) are among the factors that play essential roles in regulating follicle and oocyte development through their cargo molecules that include microRNAs (miRNAs). This study aimed to investigate small-EV (s-EV) miRNAs in porcine FFs and their potential association with oocyte quality.

Methods

Individual aspirated oocytes were stained with lissamine green B stain (LB), a vital stain for oocyte quality, and each oocyte was classified as high-quality (unstained; HQ) or low-quality (stained; LQ). FFs corresponding to oocytes were pooled together into HQ and LQ groups. Small-EVs were isolated from FFs, characterized, and their miRNA cargo was identified using the Illumina NovaSeq sequencing platform. Additionally, s-EVs from the HQ and LQ groups were utilized to investigate their effect on oocyte development after co-incubation during in vitro maturation.

Results

A total of 19 miRNAs (including miR-125b, miR-193a-5p, and miR-320) were significantly upregulated, while 23 (including miR-9, miR-206, and miR-6516) were downregulated in the HQ compared to the LQ group. Apoptosis, p53 signaling, and cAMP signaling were among the top pathways targeted by the elevated miRNAs in the HQ group while oocyte meiosis, gap junction, and TGF-beta signaling were among the top pathways targeted by the elevated miRNAs in the LQ group. The supplementation of small-EVs during maturation does not affect the oocyte developmental rates. However, LQ s-EVs increase the proportion of oocytes with homogeneous mitochondrial distribution and decrease the proportion of heterogeneous distribution.

Conclusion

Our findings indicated that FF-EVs contain different miRNA cargos associated with oocyte quality and could affect the mitochondrial distribution patterns during oocyte maturation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40104-022-00723-1.

The role of extracellular vesicles in animal reproduction and diseases

Extracellular vesicles (EVs) are nanosized membrane-enclosed compartments that serve as messengers in cell-to-cell communication, both in normal physiology and in pathological conditions. EVs can transfer functional proteins and genetic information to alter the phenotype and function of recipient cells, which undergo different changes that positively affect their structural and functional integrity. Biological fluids are enriched with several subpopulations of EVs, including exosomes, microvesicles (MVs), and apoptotic bodies carrying several cargoes, such as lipids, proteins, and nucleic acids. EVs associated with the reproductive system are actively involved in the regulation of different physiological events, including gamete maturation, fertilization, and embryo and fetal development. EVs can influence follicle development, oocyte maturation, embryo production, and endometrial-conceptus communication. EVs loaded with cargoes are used to diagnose various diseases, including pregnancy disorders; however, these are dependent on the type of cell of origin and pathological characteristics. EV-derived microRNAs (miRNAs) and proteins in the placenta regulate inflammatory responses and trophoblast invasion through intercellular delivery in the placental microenvironment. This review presents evidence regarding the types of extracellular vesicles, and general aspects of isolation, purification, and characterization of EVs, particularly from various types of embryos. Further, we discuss EVs as mediators and messengers in reproductive biology, the effects of EVs on placentation and pregnancy disorders, the role of EVs in animal reproduction, in the male reproductive system, and mother and embryo cross-communication. In addition, we emphasize the role of microRNAs in embryo implantation and the role of EVs in reproductive and therapeutic medicine. Finally, we discuss the future perspectives of EVs in reproductive biology.

Involvement of extracellular vesicle-encapsulated miRNAs in human reproductive disorders: a systematic review

In recent years, extracellular vesicles (EVs) have emerged as essential players in cell-to-cell communication, particularly having an active regulating role in biological systems. Because reproductive-associated processes are not exempt of this communication, multiple studies have been devoted to this realm, focusing on gamete maturation, embryo implantation or fetal development. The aim of the present review was to comprehensively and systematically collect evidence about the function of the microRNA (miRNA) encapsulated in EVs isolated from different reproductive tissues or fluids in reproductive-related diseases. Following PRISMA guidelines, we conducted a systematic search of the literature published in MEDLINE-PubMed until the end of February 2021. After selection, 32 studies were included in the qualitative review comparing the miRNA expression profile in EVs between different pathological disorders. Most reports showed the potential of the miRNAs carried by EVs to be used as putative biomarkers of reproductive disorders, including pregnancy affections, disease progression and quality of preimplantation embryos. The most relevant miRNAs were found to be highly heterogeneous among studies, with some conflicting results. Further research is thus warranted to address whether cofounding factors, such as the methods to isolate EVs and miRNAs, the subset of EVs, the criteria of patient selection, the timing of sample retrieval, or any other factor, may explain the inconsistencies between studies.

Report of Exosomes Isolated from a Human Uterine Leiomyoma Cell Line and Their Impact on Endometrial Vascular Endothelial Cells

Uterine leiomyomas are the most common pelvic tumor in women of reproductive age; they cause irregular heavy menstrual bleeding leading to anemia and subsequent negative effects on quality of life. Exosomes have arisen as main players of disease progression in several illnesses, including a range of benign and malignant conditions; however, their role in leiomyomas' pathophysiology remains unknown. We investigated the effect of exosomes derived from human uterine leiomyoma tumor cells (HULM) and human myometrial cells (UTSM) on the behavior of human endometrial microvascular endothelial cells (HEMEC). HULM- and UTSM-derived exosomes were isolated and cocultured with HEMECs. Then, cell proliferation, mRNA expression, tube formation assay, and RNA-seq were performed. Treatment of HEMEC with HULM-derived exosomes increased cell proliferation by 60% compared to control untreated cells, upregulated C-MYC and VEGFA expression levels, and increased tube formation, length, and branching (markers of angiogenesis). Profiling of miRNA revealed that 84 miRNAs were significantly downregulated and 71 were upregulated in HULM-derived exosomes compared to UTSM-derived exosomes. These findings suggest that HULM-derived exosomes might have effects on HEMEC function, containing factors that enhance endometrial proliferation and angiogenesis, which may contribute to heavy menstrual bleeding. Further research on exosomes in uterine leiomyoma may identify possible novel biomarkers for treatment.

Role of miRNAs in preimplantation embryo development and their potential as embryo selection biomarkers

CONTEXT

MicroRNAs (miRNAs) play different roles in oocyte fertilisation, degradation of maternal transcripts, embryo development, and implantation. During in vitro fertilisation (IVF), different miRNAs are released from embryos into the spent culture media (SCM) that can potentially reflect the status of the embryo.

AIMS

This study is the assessment of miRNAs, which secreted in SCM during the IVF cycles can be used as noninvasive biomarkers to predict an embryo's ability to form a blastocyst, implant, and give live birth.

METHODS

Systematic literature search was conducted to review all recent studies about miRNAs as potential non-invasive biomarkers for selecting the best embryos in the assisted reproductive technology (ART) cycle.

KEY RESULTS

Studies have shown that levels of some miRNAs in the SCM have an association with the implantation potential and pregnancy outcome of the embryo.

CONCLUSIONS

Embryo-secreted miRNAs can be used as potential non-invasive biomarkers for selecting the best embryos in the ART cycle. Unfortunately, few human studies evaluated the association between ART outcomes and miRNAs in SCM.

IMPLICATIONS

This review can pave the way for further miRNAs transcriptomic studies on human embryo culture media and introducing a specific miRNA profile as a multivariable prediction model for embryo selection in IVF cycles.

Follicular Fluid-Derived Exosomal MicroRNA-18b-5p Regulates PTEN-Mediated PI3K/Akt/mTOR Signaling Pathway to Inhibit Polycystic Ovary Syndrome Development

Small RNA sequences in follicular fluid (FF)-derived exosomes (extracellular vesicles contain proteins, DNA, and RNA) vitally function in the development of polycystic ovary syndrome (PCOS). It has been identified that microRNA (miR)-18b-5p is one of miRs that differ between control and PCOS women that passed the false discovery rate, and phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is an important modifier of biological functions of ovarian granulosa cells (GCs) in PCOS. However, whether miR-18b-5p could functionally mediate the progression of PCOS via PTEN was not clarified completely, which was the issue we wanted to solve in our research. FF-derived exosomes were isolated using an extraction kit. KGN cells were co-cultured with miR-18b-5p-modified exosomes or transfected with a PTEN-related vector. After treatment, cell proliferation and apoptosis were observed. A rat model of PCOS was established by letrozole and then injected with miR-18b-5p-modified exosomes. Then, serum follicle-stimulating hormone (FSH), luteinizing hormone (LH), testosterone, and estradiol (E2) levels in PCOS rats were measured. miR-18b-5p, PTEN, and phosphatidylinositol 3 kinases/protein kinase B/mammalian target of rapamycin (PI3K/Akt/mTOR) pathway-related genes were tested. In PCOS patients, miR-18b-5p was downregulated, and PTEN was highly expressed in FF and GCs. PTEN knockdown increased KGN cell proliferation and limited apoptosis. FF-derived exosomes stimulated proliferation and suppressed apoptosis of KGN cells; decreased FSH, LH, and testosterone; and increased E2 in PCOS rats. Upregulating miR-18b-5p further enhanced the inhibitory effects of exosomes on suppressing the progression of PCOS. miR-18b-5p targeted PTEN and could activate PI3K/Akt/mTOR pathway. miR-18b-5p produced by FF-derived exosomes reduces PTEN expression and promotes the activation of the PI3K/Akt/mTOR signaling pathway to improve PCOS. Based on that, circulating miR-18b-5p levels can contribute to the progression of PCOS complications.

Extracellular vesicle research in reproductive science- Paving the way for clinical achievements

Mammalian conception involves a multitude of reciprocal interactions via a molecular dialogue between mother and conceptus. Extracellular vesicles (EVs) are secreted membrane-encapsulated particles that mediate cell-to-cell communication in various contexts. EVs, which are present in seminal, follicular, oviductal, and endometrial fluids, as well as in embryo secretions, carry molecular constituents that impact gamete maturation, fertilization, early embryo development, and embryo-maternal communication. The distribution, concentration, and molecular cargo of EVs are regulated by steroid hormones and the health status of the tissue of origin, and thus are influenced by menstrual phase, stage of conception, and the presence of infertility-associated diseases. EVs have been recognized as a novel source of biomarkers and potential reproductive medicine therapeutics, particularly for assisted reproductive technology (ART). There are still many technological and scientific hindrances to be overcome before EVs can be used in clinical diagnostic and therapeutic ART applications. Issues to be resolved include the lack of standardized measurement protocols and an absence of absolute EV quantification technologies. Additionally, clinically suitable and robust EV isolation methods have yet to be developed. In this review, we provide an overview of EV-mediated interactions during the early stages of reproduction from gamete maturation to embryo implantation and then outline the technological progress that must be made for EV applications to be translated to clinical settings.

Protein source in maturation media affects gene expression in cumulus cells and embryo development in cattle

We aimed to evaluate if protein source (PS) alterations during IVM affect embryo sex/development and gene expression profile in cumulus cells (CCs). Bovine oocytes were matured and cultured in the presence of FBS or BSA. Then, the PS effect during IVM on gene expression (GPC4, VCAN, GHR, PTGS2, and ALCAM) was determined. CC biopsy was removed before and after IVM treatments. After fertilization and cultured, CCs were grouped according to their fate into CCs from immature COCs, CCs from COCs that did or did not result in embryos (according to PS). Results showed that when the culture was performed in FBS presence, blastocyst rate was higher (p < 0.05) than BSA. However, when embryos were cultured with BSA, no effect (p > 0.05) of PS during IVM was observed. PS used during IVM did not affect embryos sex (p > 0.05) but changed VCAN, GHR, PTGS2, and ALCAM genes expression. No differences (p > 0.05) were observed between immature and mature CCs groups in gene expression, regardless of their fate. Only the GHR gene was related to embryo production but just with FBS on IVM. In conclusion, PS can affect embryo development when using the serum on IVM and IVC, influences CCs gene expression, and has to be considered when studying oocyte quality markers.

Comparison of MicroRNA Profiles in Extracellular Vesicles from Small and Large Goat Follicular Fluid

Simple Summary

Ovarian follicular development is associated with ovulation and is further related to litter size in goats. Extracellular vesicles (EVs) derived from miRNAs within follicular fluid undergo dynamic changes, and, together with follicle growth, may be considered as potential regulators of follicular development. However, the function and changes in EVs remain ambiguous. Here, we identified miRNA changes in EVs from small to large goat follicular fluid. Using bioinformatics tools, we demonstrated the existence of differentially expressed miRNAs in EVs from follicles of different sizes that are responsible for an altered biological effect. This study contributes to a better understanding of follicular development in goats.

Abstract

Extracellular vesicles (EVs), which exist in the follicular fluid of ruminant ovaries, are considered as cargo carriers for the transfer of biomolecules to recipient cells. However, the functions and changes in EVs in antral follicles remain ambiguous. In the present study, we isolated and characterized EVs from goat follicular fluid by means of differential ultracentrifugation and Western blotting of marker proteins. Bioinformatics tools were used to detect miRNA expression levels in EVs. Different miRNA expression patterns of EVs exist in small to large follicles. Thirteen differentially expressed miRNAs (seven upregulated and six downregulated) were identified and used for analysis. A total of 1948 predicted target genes of 13 miRNAs were mapped to signaling pathways, and three significantly enriched pathways (FoxO, MAPK, and PI3K-AKT signaling pathways) were involved in follicular development, as revealed by KEGG enrichment analysis. Our findings suggest that EVs in follicular fluid play biofunctional roles during follicular development in goats.

microRNA-10b promotes the apoptosis of bovine ovarian granulosa cells by targeting plasminogen activator inhibitor-1

Granulosa cells (GCs) are essential somatic cells in the ovaries, and apoptosis of GCs causes follicular atresia. microRNA-10b (miR-10b) is pivotal for cell apoptosis. However, currently, little is known about the role of miR-10b in bovine ovarian GCs (BGCs). In this study, the effect of miR-10b on the apoptosis of BGCs was investigated. Our results showed that the overexpression of miR-10b could increase the apoptosis rate of BGCs, which is associated with the increased expression of Caspase-3 and decreased expression ratio of Bcl-2/Bax (P < 0.05). Furthermore, plasminogen activator inhibitor-1 (PAI-1) was confirmed to be a validated target of miR-10b in BGCs using dual-luciferase reporter analysis, and transfection of miR-10b mimics decreased the expression of PAI-1 (P < 0.05). In addition, overexpression of PAI-1 significantly inhibited BGC apoptosis (P < 0.05), and PAI-1 could alleviate BGC apoptosis induced by miR-10b (P < 0.05). Subsequently, phosphatidylinositol-3-kinase/protein kinase B (PI3K/AKT) was found to be the downstream pathway of PAI-1 by RNA-Seq analysis and verified by Western blot. Finally, a PI3K/AKT inhibitor (Miltefosine) was used to inhibit the PI3K/AKT pathway, which reversed the inhibitory effect of PAI-1 on the apoptosis of BGCs (P < 0.05), and enhanced the promotion effect of miR-10b on the apoptosis of BGCs (P < 0.05). Our results indicated that miR-10b promotes BGC apoptosis by targeting PAI-1 to regulate the PI3K/AKT pathway.

Association of microRNAs With Embryo Development and Fertilization in Women Undergoing Subfertility Treatments: A Pilot Study

Objective: Small non-coding RNAs, known as microRNAs (miRNAs), have emerging regulatory functions within the ovary that have been related to fertility. This study was undertaken to determine if circulating miRNAs reflect the changes associated with the parameters of embryo development and fertilization.

Methods: In this cross-sectional pilot study. Plasma miRNAs were collected from 48 sequentially presenting women in the follicular phase prior to commencing in vitro fertilization (IVF). Circulating miRNAs were measured using locked nucleic acid (LNA)-based quantitative PCR (qPCR), while an updated miRNA data set was used to determine their level of expression.

Results: Body mass index and weight were associated with the miRNAs let7b-3p and miR-375, respectively (p &lt; 0.05), with the same relationship being found between endometrium thickness at oocyte retrieval and miR-885-5p and miR-34a-5p (p &lt; 0.05). In contrast, miR-1260a was found to be inversely associated with anti-Mullerian hormone (AMH; p = 0.007), while miR-365a-3p, miR122-5p, and miR-34a-5p correlated with embryo fertilization rates (p &lt; 0.05). However, when omitting cases of male infertility (n = 15), miR122-5p remained significant (p &lt; 0.05), while miR-365a-3p and miR-34a-5p no longer differed; interestingly, however, miR1260a and mir93.3p became significant (p = 0.0087/0.02, respectively). Furthermore, age was negatively associated with miR-335-3p, miR-28-5p, miR-155-5p, miR-501-3p, and miR-497-5p (p &lt; 0.05). Live birth rate was negatively associated with miR-335-3p, miR-100-5p, miR-497-5p, let-7d, and miR-574-3p (p &lt; 0.05), but these were not significant when age was accounted for.However, with the exclusion of male factor infertility, all those miRNAs were no longer significant, though miR.150.5p emerged as significant (p = 0.042). A beta-regression model identified miR-1260a, miR-486-5p, and miR-132-3p (p &lt; 0.03, p = 0.0003, p &lt; 0.00001, respectively) as the most predictive for fertilization rate. Notably, changes in detectable miRNAs were not linked to cleavage rate, top quality embryos (G3D3), and blastocyst or antral follicle count. An ingenuity pathway analysis showed that miRNAs associated with age were also associated with the variables found in reproductive system diseases.

Conclusion: Plasma miRNAs prior to the IVF cycle were associated with differing demographic and IVF parameters, including age, and may be predictive biomarkers of fertilization rate.

Molecular profiling of follicular fluid microRNAs in young women affected by Hodgkin lymphoma

RESEARCH QUESTION

Treatments for Hodgkin lymphoma have improved but one of their common effects is gonadal toxicity, which contributes to fertility damage of patients and induces temporary or irreversible loss of fertility. Could micro-RNA (miRNA) expression profiles in follicular fluid be influenced by Hodgkin lymphoma? Could their alteration affect molecular pathways involved in follicle growth and oocyte maturation?

DESIGN

miRNA expression profile was investigated in follicular fluid samples from young women affected by Hodgkin lymphoma compared with healthy controls by NanoString technology. Bioinformatic analysis was used to verify miRNA involvement in follicle development and miRNA deregulation with Hodgkin lymphoma in a larger cohort of follicular fluid samples was confirmed by real-time quantitative polymerase chain reaction.

RESULTS

Thirteen miRNAs are deregulated in Hodgkin lymphoma samples compared with controls and are involved in molecular pathways related to cancer, gametogenesis and embryogenesis. Among them, let-7b-5p, miR-423-5p, miR-503-5p, miR-574-5p and miR-1303 are implicated in biological processes related to follicle development and oocyte maturation. Let-7b-5p holds the central position in the regulatory network of miRNA-mRNA interactions, has the highest number of mRNA target genes shared with the other differentially expressed miRNAs and is significantly downregulated in Hodgkin lymphoma follicular fluid samples.

CONCLUSIONS

These data led us to question the potential influence of miRNA deregulation on oocyte quality. Further studies are needed to verify the reproductive potential of young patients with Hodgkin lymphoma before starting chemotherapy protocols and an adequate protocol of fertility preservation needs to be guaranteed.

New biomarkers in peripheral blood of patients with ovarian cancer: high expression levels of miR-16-5p, miR-17-5p, and miR-638

OBJECTIVES

Ovarian cancer is one of the most fatal gynecologic malignities. miR-16-5p, miR-17-5p, and miR-638 genes were found to have been associated with ovarian cancer in accordance with the data obtained from the previous microarray research performed by Tuncer et al. (J Ovarian Res 13(1):99, 2020). The expression levels of these miRNAs in the peripheral blood samples of 142 ovarian cancer patients, and 97 healthy controls were investigated for performing the validation, and to identify whether these genes were the possible biomarkers to be used in the early diagnosis of high-risk ovarian cancer patients, and in the prognosis of patients.

METHODS

The miRNA expression analysis was performed using the miRNA-specific cDNA synthesis, and real-time PCR methods following the RNA isolation from the peripheral blood lymphocytes.

RESULTS

miR-16-5p, miR-17-5p, and miR-638 miRNA gene expression levels were found to have twofold higher expression levels in patient groups compared with the gene expression levels in healthy controls, and were statistically significant (p < 0.05). In addition, the comparison of the miRNA expression levels with the clinical data of patients showed that there was a significant difference with smoking history and the increased expression level of miR-17-5 (p: 0.007). There was a significant difference between the increased expression level of miR-638 with the locally advanced stage, and abdominal/pelvic metastatic patients (p: 0.03).

CONCLUSIONS

The obtained data suggest that miR-16-5p, miR-17-5p, and miR-638 molecules might be the noninvasive biomarkers in identifying the ovarian cancer. However, the investigation and monitoring of the changeability of these biomarkers in benign ovarian diseases, and during the treatment must be performed in future studies for identifying the accurate diagnostic, and prognostic features of miRNAs.

Age-related miRNome landscape of cumulus oophorus cells during controlled ovarian stimulation protocols in IVF cycles

STUDY QUESTION

Is the microRNA (miRNA) expression pattern of cumulus oophorus cells (COCs) in women undergoing medically assisted reproduction (MAR) procedures differentially modulated according to patient age and gonadotropin treatment strategy?

SUMMARY ANSWER

Maternal age is an independent factor impacting miRNA expression in COCs while gonadotropin treatment may affect follicular miRNA expression and IVF efficacy.

WHAT IS KNOWN ALREADY

Epigenetic mechanisms in female infertility are complex and poorly studied. DNA methylation, histone modifications, miRNAs and nucleosome positioning influence cellular machinery through positive and negative feedback mechanisms either alone or interactively. miRNAs are important regulators during oogenesis, spermatogenesis and early embryogenesis, and are reported to play a role in regulating crosstalk between the oocyte and COCs. Although miRNome analysis has been performed in female human reproductive tissues (endometrium, myometrium, cervix and ovaries), epigenetic modifications in women with infertility have not been explored in detail. In addition, the impact of gonadotropin treatments during MAR on miRNA expression in COCs has not been fully investigated.

STUDY DESIGN, SIZE, DURATION

This study was carried out in 53 COC samples obtained from mature metaphase II (MII) oocytes in 53 women undergoing MAR treatment. A total of 38 samples for assay development were pooled by maternal age and gonadotropin treatment into four predetermined subgroups: ≥36 years and recombinant human FSH (r-hFSH), n = 10; ≥36 years and r-hFSH+ recombinant human-luteinizing hormone (r-hLH), n = 10; ≤35 years and r-hFSH, n = 9; ≤35 years and r-hFSH+r-hLH, n = 9. miRNome profiles were determined and compared between subgroups. Expression of defined miRNAs was validated in the remaining fifteen samples, representative of each subgroup, by quantitative polymerase chain reaction (PCR).

PARTICIPANTS/MATERIALS, SETTING, METHODS

COCs were processed for miRNA-enriched total RNA extraction and pooled in homogeneous subgroups to obtain a sufficient amount and quality of starting material to perform the analysis. Each pooled sample underwent miRNA profiling using PCR assay system to examine expression of 752 human miRNAs without pre-amplification. Data were analyzed using the delta-delta Ct method for relative quantitation and prediction of target genes (with at least four algorithms predicting the same miRNA-gene interaction pair (HIT)>4). The miRSystem database provided functional annotation enrichment (raw P-value <0.05) of co-expressed miRNAs.

MAIN RESULTS AND THE ROLE OF CHANCE

We found distinctive miRNA expression profiles in each subgroup correlating with age and MAR stimulation. In addition, a number of selective and co-expressed miRNAs were revealed by comparative analysis. A cluster of 37 miRNAs were commonly but differentially expressed in all four pools. Significant differences were observed in expression regulation of 37 miRNAs between age groups (≤35 or ≥36) in women receiving r-hFSH+r-hLH compared to those receiving r-hFSH alone. Higher concentrations and increased numbers of miRNAs were recorded in younger than in older patients, regardless of treatment. Functional and expression studies performed to retrieve common miRNome profiles revealed an enrichment of biological functions in oocyte growth and maturation, embryo development, steroidogenesis, ovarian hyperstimulation, apoptosis and cell survival, glucagon and lipid metabolism, and cell trafficking. The highest scored pathways of target genes of the 37 common miRNAs were associated with mitogen-activated protein kinase (MAPK) signaling pathways, G alpha signaling, transcription regulation, tight junctions, RNA polymerase I and III, and mitochondrial transcription. We identified a potential age- and MAR stimulation-dependent signature in the miRNA landscape of COCs.

LIMITATIONS, REASONS FOR CAUTION

We cannot rule out the possibility that other unknown individual genetic or clinical factors may have interfered with the reported results. Since miRNA profiling was conducted with a predefined array of target probes, other miRNA molecules, potentially modulated by age and hormonal stimulation, may have been missed in this study.

WIDER IMPLICATIONS OF THE FINDINGS

miRNA expression in COCs is modulated by gonadotropin treatment and correlates strongly with age. A better understanding of the expression patterns and functions of miRNAs may lead to the development of novel therapeutics to treat ovarian dysfunction and improve fertility in older women.

STUDY FUNDING/COMPETING INTEREST

This study was funded by Merck KGaA, Darmstadt, Germany. All authors declared no competing interest, except SL and TD who are fully employed by Merck KGaA.

TRIAL REGISTRATION NUMBER

N/A

Extracellular microRNAs: key players to explore the outcomes of in vitro fertilization

BACKGROUND

MicroRNAs (miRNAs) are small RNA molecules that modulate post-transcriptional gene regulation. They are often used as promising non-invasive biomarkers for the early diagnosis of cancer. However, their roles in assisted reproduction are still unknown.

METHODS

This prospective study was designed to evaluate the expression profiles of seven extracellular miRNAs (miR-7-5p, miR-202-5p, miR-378-3p, miR-224, miR-320a, miR-212-3p, and miR-21-5p) in human follicular fluid (FF) to explore the outcomes of in vitro fertilization (IVF). Of 255 women, 145 were without polycystic ovary syndrome (PCOS), and their ovarian assets were normal (NOR), while 110 were with normo-androgenic PCOS.

RESULTS

The combination of six FF miRNAs expression profile discriminated between PCOS and NOR women with a sensitivity of 79.2% and a specificity of 87.32% (AUC = 0.881 [0.61; 0.92], p = 0.001). MiR-202-5p significantly had a lower abundance level, and miR-378-3p had a high abundance level in pooled FF samples from patients treated with human menopausal gonadotropin (hMG) than those treated with recombinant follicle-stimulating hormone (rFSH) (p < 0.001). Our results showed that miRNA-320a was significantly different in top-quality embryos versus non-top-quality embryos on day 3 in NOR patients with a sensitivity of 80% and specificity of 71%, (AUC = [0.753 (0.651; 0.855)], p = 0.001). For clinical pregnancy outcome prediction, FF miRNA-21 exhibited high sensitivity (74.8%) and specificity (83.7%) with the AUC value of 0.774 (0.682; 0.865).

CONCLUSION

Conclusively, our results provide evidence that miR-7-5p, miR-378-3p, miR-224, miR-212-3p were a differentially high expression in normo-androgenic PCOS patients than NOR patients. While miRNA-320a was significantly different in top-quality embryos versus non-top-quality embryos on day 3 (p = 0.001). The expression level of FF miR-212-3p was significantly related to the probability of embryos to develop into a high-quality blastocyst in patients with normal ovarian reserve.

MicroRNA as Potential Biomarkers of Platelet Function on Antiplatelet Therapy: A Review

MicroRNAs (miRNAs) are small, non-coding RNAs, able to regulate cellular functions by specific gene modifications. Platelets are the major source for circulating miRNAs, with significant regulatory potential on cardiovascular pathophysiology. MiRNAs have been shown to modify the expression of platelet proteins influencing platelet reactivity. Circulating miRNAs can be determined from plasma, serum, or whole blood, and they can be used as diagnostic and prognostic biomarkers of platelet reactivity during antiplatelet therapy as well as novel therapeutic targets in cardiovascular diseases (CVDs). Herein, we review diagnostic and prognostic value of miRNAs levels related to platelet reactivity based on human studies, presenting its interindividual variability as well as the substantial role of genetics. Furthermore, we discuss antiplatelet treatment in the context of miRNAs alterations related to pathways associated with drug response.

Extracellular vesicles and female reproduction

Extracellular vesicles (EVs) are nano-sized membrane bound complexes that have been identified as a mean for intercellular communication between cells and tissues both in physiological and pathological conditions. These vesicles contain numerous molecules involved in signal transduction including microRNAs, mRNAs, DNA, proteins, lipids, and cytokines and can affect the behavior of recipient cells. Female reproduction is dependent on extremely fine-tuned endocrine regulation, and EVs may represent an added layer that contributes to this regulation. This narrative review article provides an update on the research of the role of EVs in female reproduction including folliculogenesis, fertilization, embryo quality, and implantation. We also highlight potential pitfalls in typical EV studies and discuss gaps in the current literature.

Identification of small extracellular vesicle-linked miRNA specifically derived from intrafollicular cells in women with polycystic ovary syndrome

RESEARCH QUESTION

This study aimed to identify small extracellular vesicle (sEV)-linked microRNAs (miRNA) specifically derived from intrafollicular cells in women with polycystic ovary syndrome (PCOS) and to investigate their biological functions.

DESIGN

A total of 120 women were recruited from September 2017 to October 2018. To investigate miRNA profiles in sEV derived from follicular fluid and serum, 30 women with PCOS and 30 without PCOS were included for a miRNA microarray containing probes interrogating 2549 human miRNA. To study the expression levels of differentially expressed miRNA, sEV in follicular fluid obtained from another 30 PCOS and 30 non-PCOS patients were used for quantitative real-time polymerase chain reaction analysis.

RESULTS

A total of 281 sEV-linked miRNA specifically derived from intrafollicular cells were identified, 179 of which were expressed in both the PCOS and non-PCOS groups. Twenty-six of the 179 intrafollicle-specific sEV-linked miRNA were predicted to target 1537 genes. Functional analysis suggested that these genes were involved in pathways related to folliculogenesis, including the MAPK, and PI3K-Akt signalling pathways. Quantitative real-time polymerase chain reaction analysis showed that the expression of seven intrafollicle-specific sEV-linked miRNA was significantly higher in follicular fluid-derived sEV in women with PCOS than in women without it. These miRNA and their corresponding target genes were identified as being involved in the MAPK signalling pathway and oocyte meiosis.

CONCLUSIONS

The data suggest that the aberrantly expressed miRNA and their target genes might be associated with PCOS, providing novel insights into the molecular mechanisms underlying regulation of folliculogenesis and oocyte maturation in PCOS.

The Emerging Roles and Therapeutic Potential of Extracellular Vesicles in Infertility

Infertility is becoming much more common and affects more couples. The past years witnessed the rapid development of the diagnosis and treatment upon infertility, which give numerous coupled more opportunities become parents. Extracellular vesicles are known as nano-sized membrane vesicles to play a major role in intracellular communication. In recent years, several basic and clinical studies have tried to investigate the correlation between the reproductive health/disorder and extracellular vesicles. However, the mechanism is still unclear. In this review, we reviewed the relationship between reproductive physiology and extracellular vesicles, and then collectively focused on the recent findings on the relationship between extracellular and infertility, and its consequent influence on the novel insight regarding the therapeutic strategies for infertility in the future clinical practice.

Association of exosomal microRNAs in human ovarian follicular fluid with oocyte quality

The postponement of childbearing by women has led to an increase in infertility. The reproductive aging process leads to a decrease in both the quantity and quality of oocytes. The aim of this study was to investigate exosomal microRNAs in human ovarian follicular fluid and explore their potential association with oocyte quality. We collected ovarian follicle fluid from 68 patients and assigned the patients to A (superior oocyte quality) or B (poor oocyte quality) group according to their oocyte quality. Exosomal miRNAs were extracted, library constructed and sequenced using the Illumina HiSeq platform. Subsequently, we analyzed exosomal miRNA expression, predicted the miRNA target genes, and enriched Gene Ontology terms using GOSeq. Kyoto Encyclopedia of Genes and Genomes pathway analysis was performed using miRanda. A total of 47 miRNAs were found to be significantly differentially expressed between group A and group B (p < 0.05). Among nine differentially expressed miRNAs that were previously known, seven were upregulated in group B. In silico analysis indicated that several of these exosomal miRNAs were involved in pathways implicated in oocyte quality. Analysis of the expression of exosomal miRNAs in human ovarian follicular fluid showed that they were critical for maintaining oocyte quality. Our findings provide the basis for further investigations of the functions of exosomal miRNAs in the ovarian microenvironment and suggest that these exosomal miRNAs may be potential biomarkers for evaluating oocyte quality. The findings are potentially important to maintain oocyte quality in clinical settings.

Melatonin levels and microRNA (miRNA) relative expression profile in the follicular ambient microenvironment in patients undergoing in vitro fertilization process

PURPOSE

Intrafollicular fluid (IFF) melatonin plays a decisive role in maintaining granulosa cells' DNA integrity and protects them against apoptosis. It reduces oxidative stress and improves the oocyte quality with a higher fertilization rate.

METHOD

This prospective study investigated the antioxidant property of IFF melatonin and its impact on IVF outcome parameters. We also explored the relative expression of five microRNAs (miR-663b, miR-320a, miR-766-3p, miR-132-3p, miR-16-5p) and levels of cell-free DNA (cfDNA) by real-time PCR in unexplained infertile patients. We collected 425 follicular fluid (FF) samples containing mature oocytes from 295 patients undergoing IVF.

RESULTS

Patients were subgrouped based on IFF melatonin concentration (group A ≤ 30 pg/mL, group B > 70 to ≤ 110 pg/mL, group C > 111 to ≤ 385 pg/mL). Our results showed that patients with ≤ 30 pg/mL IFF melatonin levels have significantly higher oxidative stress markers, cfDNA levels, and lower relative expression of miR-663b, miR-320a, miR-766-3p, miR-132-3p, and miR-16-5p compared to other subgroups (p < 0.001). Similarly, they have a low fertilization rate and a reduced number of high-quality day 3 embryos.

CONCLUSION

Findings suggest that the therapeutic use of melatonin produces a considerable rise in the number of mature oocytes retrieved, fertilization rate, and good-quality embryo selection. Furthermore, miRNA signature enhances the quality of embryo selection, thus, may allow us to classify them as non-invasive biomarkers to identify good-quality embryos.

Plasma extracellular vesicle miRNAs as potential biomarkers of superstimulatory response in cattle

The ability to predict superstimulatory response would be a beneficial tool in assisted reproduction. Using small RNAseq technology, we profiled extracellular vesicle microRNA (EV-miRNA) abundance in the blood plasma of heifers exhibiting variable responses to superstimulation. Estrous synchronized crossbred beef heifers (n = 25) were superstimulated and blood samples were collected from each heifer on Day 7 of consecutive unstimulated (U) and superstimulated (S) cycles. A subset of high (H) and low (L) responders was selected depending on their response to superstimulation and EV-miRNA profiles were analysed at both time-points in each heifer. Approximately 200 known miRNAs were detected in each sample with 144 commonly detected in all samples. A total of 12 and 14 miRNAs were dysregulated in UH vs. UL and in SH vs. SL heifers, respectively. Interestingly, miR-206 and miR-6517 exhibited the same differential expression pattern in H compared to L heifers both before and after superstimulation. Pathway analysis indicated that circadian rhythm and signaling pathways were among the top pathways enriched with genes targeted by dysregulated miRNAs in H vs. L responding heifers. In conclusion, heifers with divergent ovarian responses exhibited differential expression of plasma EV-miRNAs which may be used as a potential biomarker to predict superstimulation response.

Exosomes as a Potential Tool for Supporting Canine Oocyte Development

Simple Summary

To date, extracellular vesicles, including exosomes, have markedly gained attention in scientific research because of their physiological homogeneity as well as stability for transporting regulatory molecules to recipient cells. Recently, it has been shown that exosomes impact gametes and embryo development in several mammalian species; however, there is still scant information on the physiological effects of exosomes on the canine reproduction system. In this regard, we elucidate the possible roles of exosomes involvement in oviduct and cumulus-oocyte complexes mutual communications and how oviduct regulates their development via molecular signaling pathways.

Abstract

The canine oviduct is a unique reproductive organ where the ovulated immature oocytes complete their maturation, while the other mammals ovulate matured gametes. Due to their peculiar reproductive characteristics, the in vitro maturation of dog oocytes is still not wellestablished compared with other mammals. Investigations of the microenvironment conditions in the oviductal canal are required to establish a reliable in vitro maturation system in the dog. Previous studies have suggested that the oviduct and its derivatives play a key role in improving fertilization as well as embryo development. In particular, the biological function of oviduct-derived exosomes on sperm and early embryo development has been investigated in porcine, bovine, and murine species. However, the information about their functions on canine cumulus-oocyte complexes is still elusive. Recent canine reproductive studies demonstrated how oviduct-derived extracellular vesicles such as microvesicles and exosomes interact with oocyte-cumulus complexes and how they can play roles in regulating canine cumulus/oocyte communications. In this review, we summarize the physiological characteristics of canine oviduct-derived exosomes and their potential effects on cumulus cells development as well as oocyte in vitro maturation via molecular signaling pathways.

Secreted MicroRNA to Predict Embryo Implantation Outcome: From Research to Clinical Diagnostic Application

Embryo implantation failure is considered a leading cause of infertility and a significant bottleneck for in vitro fertilization (IVF) treatment. Confirmed factors that lead to implantation failure involve unhealthy embryos, unreceptive endometrium, and asynchronous development and communication between the two. The quality of embryos is further dependent on sperm parameters, oocyte quality, and early embryo development after fertilization. The extensive involvement of such different factors contributes to the variability of implantation potential across different menstrual cycles. An ideal approach to predict the implantation outcome should not compromise embryo implantation. The use of clinical material, including follicular fluid, cumulus cells, sperm, seminal exosomes, spent blastocyst culture medium, blood, and uterine fluid, that can be collected relatively non-invasively without compromising embryo implantation in a transfer cycle opens new perspectives for the diagnosis of embryo implantation potential. Compositional comparison of these samples between fertile women and women or couples with implantation failure has identified both quantitative and qualitative differences in the expression of microRNAs (miRs) that hold diagnostic potential for implantation failure. Here, we review current findings of secreted miRs that have been identified to potentially be useful in predicting implantation outcome using material that can be collected relatively non-invasively. Developing non-invasive biomarkers of implantation potential would have a major impact on implantation failure and infertility.

Extracellular vesicles in spontaneous preterm birth

Feto-maternal communication helps to maintain pregnancy and contributes to parturition at term and preterm. Endocrine and immune factor are well-reported communication mediators. Recent advances in extracellular vesicle (EV) biology have introduced them as major communication channels between the mother and fetus. EVs are round structures with a lipid bilayer membrane. EVs are generally categorized based on their size and mode of biogenesis. The most commonly reported EVs are exosomes with a size range of 30-160 nm that are formed inside the intraluminal vesicles of multivesicular body. Microvesicles (MVs) are larger than > 200 nm and formed by outward budding of plasma membrane. Vesicles are released from all cells and carry various factors that reflect the physiologic state of cell at the time of their release. Analysis of vesicle provides a snapshot of origin cell. Recent studies in perinatal medicine have shown that exosomes are key communicators between feto-maternal units, and they can cross placenta. Fetal-derived exosomes released under term labor-associated conditions can cause parturition-associated changes in maternal uterine tissues. Exosomes carrying inflammatory cargo can cause preterm birth in animal models suggesting their functional role in parturition. A few reports have profiled differences between exosome cargos from term and preterm pregnancies and indicated their biomarker potential to predict high-risk pregnancy status. There are hardly any reports on MVs and their functional roles in reproduction. Herein, we review of EVs and MVs, their characteristics, function, and usefulness predicting adverse pregnancy complications such as preterm birth.

Effects of oocyte-derived paracrine factors on release of extracellular vesicles by murine mural granulosa cells in vitro

Both oocytes and extracellular vesicles (EV) have emerged as critical regulators of mammalian follicular development; however, the possible interaction between the oocyte‐derived paracrine factor (ODPF) and EV signals has never been examined. Therefore, to explore the possibility of an interaction between oocyte and EV signals, the effects of ODPFs on the biogenesis of EVs as well as the expression levels of transcripts related to EV biogenesis in mural granulosa cells (MGCs) were examined using mice. The results showed that, while oocyte coculture has some effects on the expression levels of transcripts related to EV biogenesis, the number of EV particles present in the conditioned medium were not significantly different between ODPF‐treated and non‐treated MGCs. Therefore, oocytes have no effects on the EV biogenesis by MGCs, at least with respect to the numbers of EV particles.

Prediction of major microRNAs in follicular fluid regulating porcine oocyte development

PURPOSE

The aim of the present study was to identify key microRNAs (miRNAs) in porcine follicular fluid (FF) that regulate oocyte growth.

METHODS

miRNAs contained in FF were determined by small RNA-seq of exosome RNA. Upstream regulator miRNA was determined by ingenuity pathway analysis using differentially expressed genes in granulosa cells (GCs) between small follicles (1-2 mm in diameter) and large follicles (3-5 mm), and between follicles containing oocytes of high developmental ability and follicles containing oocytes of low developmental ability. The candidate miRNAs overlapping among the three miRNAs group were determined. Lastly, the effect of supplementation with FF, exosome-depleted FFs, or each miRNA on in vitro oocyte growth was examined.

RESULTS

The miRNAs determined were miR-17, -27, -92a, and -145. These miRNAs were found in the spent culture medium of oocytes and granulosa cells complexes and serum by small RNA sequencing. Culturing of oocytes and granulosa cells complexes collected from porcine early antral follicles (0.5-0.7 mm in diameter) with FF for 14 days improved oocyte growth; depletion of exosomes from the FFs neutralized the beneficial effect observed. miR-92a mimic increased the antrum formation and diameter, together with acetylated levels of H4K12 in oocytes. In addition, supplementation of miRNA mimics miR-17b, -92a, and -145b improved the rate of chromatin configuration, and miR-17b and -92a mimics improved the developmental ability of oocytes to the blastocyst stage.

CONCLUSION

miR-17, -92a, and -145 are major miRNA candidates in follicular fluids regulating oocyte growth.