Extra-cellular vesicles of the male genital tract: new actors in male fertility?

A Size-Exclusion Chromatography-Based Procedure for Isolating Extracellular Vesicle Subsets from Porcine Seminal Plasma

Extracellular vesicles (EVs), membrane nanoparticles (30-to-1000 nm diameter) secreted and released by most of the body functional cells, have emerged as powerful cell-to-cell messengers transferring their bioactive cargo (proteins, lipids, and nucleic acids) from donor to recipient cells. The promising potential utility of EVs as both noninvasive biomarkers and therapeutic carriers for several pathologies, including some types of cancers, has attracted increasing scientific interest. EVs can be found in all body biofluids, including seminal plasma, a complex fluid consisting mainly of a mixture of secretions of the epididymis and accessory sex glands. Seminal EVs are involved in modulating both sperm physiological processes and immune environment of the internal female genital tract, thus playing an essential indirect role in fertilization and embryo development. Seminal plasma, alike other biofluids, contains a heterogenous population of EV-subsets. However, the lack of consensus on the most accurate procedure for isolating EV-subsets has led to a poor definition of their composition/function. Currently, size exclusion chromatography (SEC), a size-selective separation method, is one of the most promising EV-isolation procedures, allowing the isolation of EVs from biological fluids in a purer, easier, cheaper, and more scalable way compared to other alternative isolation procedures. This chapter reports a SEC-based protocol, combined with differential centrifugation and ultrafiltration, to isolate two subsets of seminal EVs differing in size (large and small EVs) in the ejaculate of pigs, a livestock species of great productive interest and an outstanding animal model for human reproduction.

Proteomics of human spermatozoa

Proteomic methodologies offer a robust approach to identify and quantify thousands of proteins from semen components in both fertile donors and infertile patients. These strategies provide an unprecedented discovery potential, which many research teams are currently exploiting. However, it is essential to follow a suitable experimental design to generate robust data, including proper purification of samples, appropriate technical procedures to increase identification throughput, and data analysis following quality criteria. More than 6000 proteins have been described so far through proteomic analyses in the mature sperm cell, increasing our knowledge on processes involved in sperm function, intercommunication between spermatozoa and seminal fluid, and the transcriptional origin of the proteins. These data have been complemented with comparative studies to ascertain the potential role of the identified proteins on sperm maturation and functionality, and its impact on infertility. By comparing sperm protein profiles, many proteins involved in the acquisition of fertilizing ability have been identified. Furthermore, altered abundance of specific protein groups has been observed in a wide range of infertile phenotypes, including asthenozoospermia, oligozoospermia, and normozoospermia with unsuccessful assisted reproductive techniques outcomes, leading to the identification of potential clinically useful protein biomarkers. Finally, proteomics has been used to evaluate alterations derived from semen sample processing, which might have an impact on fertility treatments. However, the intrinsic heterogeneity and inter-individual variability of the semen samples have resulted in a relatively low overlap among proteomic reports, highlighting the relevance of combining strategies for data validation and applying strict criteria for proteomic data analysis to obtain reliable results. This mini-review provides an overview of the most critical steps to conduct robust sperm proteomic studies, the most relevant results obtained so far, and potential next steps to increase the impact of sperm proteomic data.

State-of-the-art and future perspectives in infertility diagnosis: Conventional versus nanotechnology-based assays

According to the latest World Health Organization statistics, around 50 to 80 million people worldwide suffer from infertility, amongst which male factors are responsible for around 20 to 30 % of all infertility cases while 50 % were attributed to the female ones. As it is becoming a recurrent health problem worldwide, clinicians require more accurate methods for the improvement of both diagnosis and treatment schemes. By emphasizing the potential use of innovative methods for the rapid identification of the infertility causes, this review presents the news from this dynamic domain and highlights the benefits brought by emerging research fields. A systematic description of the standard techniques used in clinical protocols for diagnosing infertility in both genders is firstly provided, followed by the presentation of more accurate and comprehensive nanotechnology-related analysis methods such as nanoscopic-resolution imaging, biosensing approaches and assays that employ nanomaterials in their design. Consequently, the implementation of nanotechnology related tools in clinical practice, as recently demonstrated in the selection of spermatozoa, the detection of key proteins in the fertilization process or the testing of DNA integrity or the evaluation of oocyte quality, might confer excellent advantages both for improving the assessment of infertility, and for the success of the fertilization process.

Relevance of multilamellar and multicompartmental vesicles in biological fluids: understanding the significance of proportional variations and disease correlation

Extracellular vesicles (EVs) have garnered significant interest in the field of biomedical science due to their potential applications in therapy and diagnosis. These vesicles participate in cell-to-cell communication and carry a diverse range of bioactive cargo molecules, such as nucleic acids, proteins, and lipids. These cargoes play essential roles in various signaling pathways, including paracrine and endocrine signaling. However, our understanding of the morphological and structural features of EVs is still limited. EVs could be unilamellar or multilamellar or even multicompartmental structures. The relative proportions of these EV subtypes in biological fluids have been associated with various human diseases; however, the mechanism remains unclear. Cryo-electron microscopy (cryo-EM) holds great promise in the field of EV characterization due to high resolution properties. Cryo-EM circumvents artifacts caused by fixation or dehydration, allows for the preservation of native conformation, and eliminates the necessity for staining procedures. In this review, we summarize the role of EVs biogenesis and pathways that might have role on their structure, and the role of cryo-EM in characterization of EVs morphology in different biological samples and integrate new knowledge of the alterations of membranous structures of EVs which could be used as biomarkers to human diseases.

The emerging role of extracellular vesicles in the testis

Extracellular vesicles (EVs) are nano-sized membrane-bounded particles, released by all cells and capable of transporting bioactive cargoes, proteins, lipids, and nucleic acids, to regulate a variety of biological functions. Seminal plasma is enriched in EVs, and extensive evidence has revealed the role of EVs (e.g. prostasomes and epididymosomes) in the male genital tract. Recently, EVs released from testicular cells have been isolated and identified, and some new insights have been generated on their role in maintaining normal spermatogenesis and steroidogenesis in the testis. In the seminiferous tubules, Sertoli cell-derived EVs can promote the differentiation of spermatogonial stem cells (SSCs), and EVs secreted from undifferentiated A spermatogonia can inhibit the proliferation of SSCs. In the testicular interstitium, EVs have been identified in endothelial cells, macrophages, telocytes, and Leydig cells, although their roles are still elusive. Testicular EVs can also pass through the blood-testis barrier and mediate inter-compartment communication between the seminiferous tubules and the interstitium. Immature Sertoli cell-derived EVs can promote survival and suppress the steroidogenesis of Leydig cells. Exosomes isolated from macrophages can protect spermatogonia from radiation-induced injury. In addition to their role in intercellular communication, testicular EVs may also participate in the removal of aberrant proteins and the delivery of antigens for immune tolerance. EVs released from testicular cells can be detected in seminal plasma, which makes them potential biomarkers reflecting testicular function and disease status. The testicular EVs in seminal plasma may also affect the female reproductive tract to facilitate conception and may even affect early embryogenesis through modulating sperm RNA. EVs represent a new type of intercellular messenger in the testis. A detailed understanding of the role of testicular EV may contribute to the discovery of new mechanisms causing male infertility and enable the development of new diagnostic and therapeutic strategies for the treatment of infertile men.

Mass Spectrometry-Based Untargeted Approaches to Reveal Diagnostic Signatures of Male Infertility in Seminal Plasma: A New Laboratory Perspective for the Clinical Management of Infertility?

Male infertility has been recognized as a global health problem. Semen analysis, although considered the golden standard, may not provide a confident male infertility diagnosis alone. Hence, there is the urgent request for an innovative and reliable platform to detect biomarkers of infertility. The rapid expansion of mass spectrometry (MS) technology in the field of the 'omics' disciplines, has incredibly proved the great potential of MS-based diagnostic tests to revolutionize the future of pathology, microbiology and laboratory medicine. Despite the increasing success in the microbiology area, MS-biomarkers of male infertility currently remain a proteomic challenge. In order to address this issue, this review encompasses proteomics investigations by untargeted approaches with a special focus on experimental designs and strategies (bottom-up and top-down) for seminal fluid proteome profiling. The studies reported here witness the efforts of the scientific community to address these investigations aimed at the discovery of MS-biomarkers of male infertility. Proteomics untargeted approaches, depending on the study design, might provide a great plethora of biomarkers not only for a male infertility diagnosis, but also to address a new MS-biomarkers classification of infertility subtypes. From the early detection to the evaluation of infertility grade, new MS-derived biomarkers might also predict long-term outcomes and clinical management of infertility.

Insights on the potential oncogenic impact of long non-coding RNA nicotinamide nucleotide transhydrogenase antisense RNA 1 in different cancer types; integrating pathway(s) and clinical outcome(s) association

Long non-coding RNAs (lncRNAs) are becoming more prevalent in the cancer field arena, with functional roles in both oncogenic and onco-suppressive pathways. Despite their widespread aberrant expression in a range of human malignancies, the biological activities of the ncRNAs majority are unknown. All showed the involvement of the lncRNA nicotinamide nucleotide transhydrogenase antisense RNA 1 (NNT-AS1). Since NNT-AS1 influences cellular proliferation, invasion, migration, apoptosis, and metastasis, this lncRNA appears to be linked to deregulating the normal cellular processes driving malignancy. This was observed in breast cancer (BC), gastric cancer (GC), colorectal cancer (CRC), epithelial ovarian cancer (EOC), and hepatocellular carcinoma (HCC). The current narrative non-systematic review will discuss "the significance of lncRNAs in cancer", as well as "lncRNAs future potential application(s) as diagnostic or predictive biomarkers", therefore, comprising an opportunity as treatment target(s). The review will have a special emphasis on lncRNA NNT-AS1.

Diversity of Extracellular Vesicles in Human Follicular Fluid: Morphological Analysis and Quantification

The oocyte microenvironment constituted by the follicular fluid (FF) is a key for the optimal development of female gametes. Its composition reflects the physiological state of the ovarian follicle. The particularity of FF is to contain a huge diversity of extracellular vesicles specific to women, in the same way as seminal plasma in men. Here, we described and compared morphological aspects of broad subcategories of human FF-related Extracellular Vesicles (EVs). EVs participate in physiological and pathological processes and have potential applications in diagnostics or therapeutics. EVs isolated from FF are involved in different biological functions related to follicular growth, oocyte maturation, and embryo development. However, knowledge on the morphology of FF-derived EVs is limited, mainly due to their sub-micrometer size and to intrinsic limitations in methods applied for their characterization. The aim of this study was to provide a comprehensive morphological description of EVs from FF of healthy subjects and quantification. EVs separation was realized by centrifugation, with comparison of the EV yield obtained from differential centrifugation and one-step ultracentrifugation. Cryo-Transmission Electron Microscopy was used to reveal the morphology, size, and phenotype of EVs. Dynamic Light Scattering (DLS) and Nanoparticle Tracking Analysis (NTA) were used to quantify and analyze the size distribution for each centrifugation step. We performed a comprehensive inventory of human follicular fluid EVs. We show that human FF contains a huge diversity of EVs. This study brings novel insights on EVs from normal FF and provides a reference for further studies of EVs in ovarian diseases.

Luminescent Gold Nanoclusters Interacting with Synthetic and Biological Vesicles

According to their high electron density and ultrasmall size, gold nanoclusters (AuNCs) have unique luminescence and photoelectrochemical properties that make them very attractive for various biomedical fields. These applications require a clear understanding of their interaction with biological membranes. Here we demonstrate the ability of the AuNCs as markers for lipidic bilayer structures such as synthetic liposomes and biological extracellular vesicles (EVs). The AuNCs can selectively interact with liposomes or EVs through an attractive electrostatic interaction as demonstrated by zetametry and fluorescence microscopy. According to the ratio of nanoclusters to vesicles, the lipidic membranes can be fluorescently labeled without altering their thickness until charge reversion, the AuNCs being located at the level of the phosphate headgroups. In presence of an excess of AuNCs, the vesicles tend to adhere and aggregate. The strong adsorption of AuNCs results in the formation of a lamellar phase as demonstrated by cryo-transmission electron microscopy and small-angle X-ray scattering techniques.

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.

Impact of Endocrine Disruptors upon Non-Genetic Inheritance

Similar to environmental factors, EDCs (endocrine-disrupting chemicals) can influence gene expression without modifying the DNA sequence. It is commonly accepted that the transgenerational inheritance of parentally acquired traits is conveyed by epigenetic alterations also known as "epimutations". DNA methylation, acetylation, histone modification, RNA-mediated effects and extracellular vesicle effects are the mechanisms that have been described so far to be responsible for these epimutations. They may lead to the transgenerational inheritance of diverse phenotypes in the progeny when they occur in the germ cells of an affected individual. While EDC-induced health effects have dramatically increased over the past decade, limited effects on sperm epigenetics have been described. However, there has been a gain of interest in this issue in recent years. The gametes (sperm and oocyte) represent targets for EDCs and thus a route for environmentally induced changes over several generations. This review aims at providing an overview of the epigenetic mechanisms that might be implicated in this transgenerational inheritance.