Motility-related microRNAs identified in pig seminal plasma exosomes by high-throughput small RNA sequencing

Seminal plasma MicroRNA dynamics in stallion semen due to progressive motility and conception success

This study aims to investigate the expression patterns of miR-34b, miR-122, let-7a in seminal plasma of stallions in relation to progressive motility and conception success, and to evaluate their potential as biomarkers. Fifteen adult stallions were enrolled in study. One ml of seminal plasma was kept at -80 °C, 2 ml of fresh semen was sampled from each stallion for sperm analysis, and the rest were used for artificial insemination only for one mare. Two groups were formed as high progressive motility (HPM; n:8) and low progressive motility (LPM; n:7), based on progressive motility. Besides, two groups were formed as positive (n:8) and negative (n:7) pregnancy groups according to 14th day pregnancy results. Motility and progressive motility values determined by computer-assisted semen analyzer. Flow cytometry was used to evaluate the viability, HMMP, PMAI, non-capacitated sperm rate and LPO parameters. MicroRNAs were evaluated with qPCR. Prediction of targets, protein-protein interactions and functional enrichment analyses were also performed. Total (82.13 ± 3.04; p < 0.01) and progressive (45.88 ± 6.03; p < 0.001) motilities, and non-capacitated sperm rates (45.76 ± 3.92; p < 0.05) were greater in HPM. Compared to LPM, miR-34b (p < 0.05) and miR-122 (p < 0.05) were upregulated in HPM approximately 11- and 6-fold, respectively. miR-34b and total motility were positively correlated (0.674; p < 0.01). Target gene analysis revealed a network of 102 genes and 421 edges. Moreover, significant interaction networks involving 19 proteins were determined. Performed enrichment analysis showed selected miRNAs significantly regulate crucial pathways. Regulatory differences of miR-34b and miR-122 in seminal plasma might serve to determine the characteristics of stallion semen.

Characterization of microRNA and Metabolite Profiles of Seminal Extracellular Vesicles in Boars

Extracellular vesicles (EVs) contain bioactive substances and mediate a multitude of physiological functions. EVs can be found in most body fluids and are particularly abundant in semen. EVs have the potential to become a biomarker for the quality of boar semen. In this study, EVs were isolated from the semen of relatively young (10 months of age, Y-EVs) and old (30 months of age, O-EVs) duroc boars using ultracentrifugation. The isolated EVs were characterized using a transmission electron microscope, nanoparticle tracking analysis, and Western blotting. MicroRNA (miRNA) profiles and metabolomes were analyzed using high-throughput sequencing and liquid chromatography-mass spectrometry, respectively. The median particle sizes of Y-EVs and O-EVs were 151.3 nm and 162.1 nm, respectively. miR-148a-3p, miR-10b, miR-21-5p, miR-10a-5p, let-7a, etc., were identified as highly enriched miRNAs in seminal EVs of boars. Comparative analysis revealed 41 differentially expressed miRNAs and 132 differential metabolites between Y-EVs and O-EVs. Notably, 18 miRNAs were upregulated in O-EVs, such as miR-339-5p, miR-125a, miR-423-3p, and miR-29c, which were mainly enriched in endocytosis, focal adhesion, and adherens junction. KEGG pathway analysis further indicated that differential metabolites were enriched in glycerophospholipid metabolism. These results provide an insight into the functional roles of seminal EVs.

Unlocking Gamete Quality Through Extracellular Vesicles: Emerging Perspectives

Extracellular vesicles (EVs) are gaining recognition for their essential role in enhancing gamete quality and improving outcomes in assisted reproductive technologies. These nanosized particles, released by cells, carry proteins, lipids, and RNAs, facilitating critical cell communication and offering the potential to enhance gamete maturation and improve fertilization rates. Most research on males has concentrated on seminal plasma, a complex fluid produced by the testes and accessory glands vital in modulating sperm fertility potential. The components of seminal plasma significantly affect sperm functionality, embryo survival, and placental development, making this a prominent area of interest in reproductive biology. The EVs within seminal plasma contribute to maintaining sperm membrane stability, enhancing motility, and promoting capacitation, which may influence the female reproductive tract following mating. In females, EVs have been identified in both the follicular and uterine environments, where effective embryo-maternal communication is crucial. The oviduct epithelium supports gamete transport and early embryonic development, with EVs found in oviductal fluid playing a key role in reproductive processes. These EVs support the embryo's growth in the nutrient-rich uterine environment. These important studies underscore the significant role of EVs in transporting essential molecular compounds to gametes and embryos, leading to an enhanced understanding and potential manipulation of reproductive processes. This review aims to summarize the current research on the benefits of EVs in gamete manipulation and embryo development, highlighting their promising implications for reproductive health.

Multi-Omics Sequencing Dissects the Atlas of Seminal Plasma Exosomes from Semen Containing Low or High Rates of Sperm with Cytoplasmic Droplets

Sperm cytoplasmic droplets (CDs) are remnants of cytoplasm that can cause a number of problems if it not shed from the sperm after ejaculation. Exosomes can rapidly bind to sperm, but it is not clear whether exosomes can affect the migration and shedding of CDs. We first extracted and characterized seminal plasma exosomes from boar semen containing sperm with low or high rates of CDs. Then, the transcriptomic and proteomic detection of these exosomes were performed to analyze the differences between the two groups of seminal plasma exosomes. The results revealed that 486 differentially expressed genes (DEGs), 40 differentially expressed proteins (DEPs), and 503 differentially expressed lncRNAs (DElncRNAs) were identified between the low CD rate group and high CD rate group. Integrative multi-omics analysis showed that exosome components may affect migration and shedding of cytoplasmic droplets by influencing cytoskeletal regulation and insulin signaling, including regulation of the actin cytoskeleton, ECM-receptor interaction, axon guidance, insulin secretion, and the insulin signaling pathway. Overall, our study systematically revealed the DEGs, DEPs, and DElncRNAs in seminal plasma exosomes between low CD rate semen and high CD rate semen, which will help broaden our understanding of the complex molecular mechanisms involved in the shedding of CDs.

Identification and Functional Analysis of miRNAs in Extracellular Vesicles of Semen Plasma from High- and Low-Fertility Boars

Artificial insemination (AI), as an efficient assisted reproduction technology, can help the livestock industry to improve livestock and poultry breeds, optimize production performance and improve reproductive efficiency. AI technology has been widely used in pig production in China, but boar fertility affects the effectiveness of AI, and more and more studies have shown that there are significant differences in the fertility of boars with similar semen quality indicators. Therefore, this study aimed to identify biomarker molecules that indicate the level of boar fertility, which is important for improving the efficiency of AI. In this study, we collected 40 mL of ejaculates per boar used for extracellular vesicle (EV) characterization in 20 boars and identified 53 differentially expressed miRNAs by small RNA sequencing, of which 44 miRNAs were up-regulated in the high-fertility seminal EVs compared with low-fertility seminal EVs, and nine miRNAs were down-regulated. miR-26a was most significantly down-regulated in the high-fertility group compared to the low-fertility group, and it was hypothesized that this miRNA could be used as a biomolecular marker of semen reproductive performance. To further determine the effect of miR-26a on sperm function, we successfully established a miR-26a overexpression model and found that miR-26a reduced sperm viability, motility, acrosome integrity, plasma membrane integrity and ATP levels. Bioinformatics analysis and dual luciferase reporter analysis revealed that miR-26a directly targets High mobility group A1 (HMGA1). In conclusion, miR-26a can be used as a biomarker to identify high and low fertility in boar semen.

The role of reproductive tract extracellular vesicles on boar sperm function

Extracellular vesicles (EVs) are abundant in reproductive tract fluids and serve as important mediators of paracrine communication, influencing the function of gametes. Sperm undergo development in the male reproductive tract and exert their function within the female reproductive tract, engaging in interactions with various types of EVs present throughout the reproductive system. Previous studies have demonstrated that both male and female reproductive tract EVs can impact sperm function by transferring regulatory cargoes to them. Nevertheless, inconsistencies of previous research regarding the effects of EVs on sperm function, coupled with a lack of investigation into the influence of female reproductive tract EVs on sperm fertilization, have left the true role and underlying mechanisms of reproductive tract EVs on sperm function largely unexplored. Given that pigs represent significant economic livestock and serve as an ideal biomedical model for human diseases, this review aims to provide a comprehensive summary of the current knowledge regarding reproductive tract EVs and their influence on boar sperm function, while highlighting their potential roles. We anticipate that this review will facilitate future research on reproductive tract EVs and their impact on sperm function, contributing to improved animal reproductive efficiency and advancements in the treatment of male infertility.

Updating Research on Extracellular Vesicles of the Male Reproductive Tract in Farm Animals: A Systematic Review

This systematic review examined research studies on extracellular vesicles (EVs) of the male reproductive tract in livestock species to summarize the research topics and methodologies used, key findings, and future directions. PubMed and Scopus were searched for time ranges up to 1 September 2024, and 1383 articles were identified. The application of screening and eligibility criteria resulted in the selection of 79 articles focusing on male reproductive EVs in livestock. Porcine and bovine male reproductive EVs were the most studied. A variety of EV isolation techniques were used, with ultracentrifugation being the most common. Characterization of male reproductive EVs in livestock was a weak point, with only 24.05% of the articles characterizing EVs according to MISEV guidelines. Inadequate characterization of EVs compromises the reliability of results. The results of 19 articles that provided a good characterization of EVs showed that male reproductive EVs from livestock species are phenotypically and compositionally heterogeneous. These papers also showed that these EVs would be involved in the regulation of sperm functionality. Research on male reproductive EVs in livestock species remains scarce, and further research is needed, which should include appropriate characterization of EVs and aim to find efficient methods to isolate them and assess their involvement in the functionality of spermatozoa and the cells of the female genital tract.

Reproductive physiology of the boar: What defines the potential fertility of an ejaculate?

Despite decades of research and handling of semen for use in artificial insemination (AI) and other assisted reproductive technologies, 5-10% of selected boar sires are still considered sub-fertile, escaping current assessment methods for sperm quality and resilience to preservation. As end-product, the ejaculate (emitted spermatozoa sequentially exposed to the composite seminal plasma, the SP) ought to define the homeostasis of the testes, the epididymis, and the accessory sexual glands. Yet, linking findings in the ejaculate to sperm production biology and fertility is suboptimal. The present essay critically reviews how the ejaculate of a fertile boar can help us to diagnose both reproductive health and resilience to semen handling, focusing on methods -available and under development- to identify suitable biomarkers for cryotolerance and fertility. Bulk SP, semen proteins and microRNAs (miRNAs) have, albeit linked to sperm function and fertility after AI, failed to enhance reproductive outcomes at commercial level, perhaps for just being components of a complex functional pathway. Hence, focus is now on the interaction sperm-SP, comparing in vivo with ex vivo, and regarding nano-sized lipid bilayer seminal extracellular vesicles (sEVs) as priority. sEVs transport fragile molecules (lipids, proteins, nucleic acids) which, shielded from degradation, mediate cell-to-cell communication with spermatozoa and the female internal genital tract. Such interaction modulates essential reproductive processes, from sperm homeostasis to immunological female tolerance. sEVs can be harvested, characterized, stored, and manipulated, e.g. can be used for andrological diagnosis, selection of breeders, and alternatively be used as additives to improve cryosurvival and fertility.

Key miRNAs of chicken seminal plasma extracellular vesicles related with sperm motility regulation

MicroRNAs (miRNAs) are bio-active elements cargoed by seminal plasma extracellular vesicles extracellular vesicles (SPEVs) which are crucial for sperm function and fertility modulation. This study aimed to isolate, characterize, and identify the miRNA expression profiles in the SPEVs from high (HSM) and low sperm motility (LSM) groups that could serve as fertility biomarkers and explain the underlying mechanisms. The isolated SPEVs were round spherical structures of approximately 50-200 nm in diameter expressing molecular markers. A total of 1006 and 1084 miRNAs were detected in HSM and LSM, respectively, with 34 being differentially expressed. Their targeted genes involved in SNARE interactions in vesicular transport, Metabolic pathways, and Apelin signaling pathway, etc. The joint analysis with mRNAs of sperm and sperm storage tubules cells highlighted the cellular communication mediated by SPEVs miRNAs, where they may rule fertility by affecting sperm maturation and amino acid metabolism. SPEVs as additives could improve fertility of fresh and frozen sperm, while the knockdown of one of the differentially expressed miRNAs, miR-24-3p, diminished this effect, indicating its crucial roles. This study expands our understanding of SPEVs miRNAs mediated sperm maturation and fertility modulation, and may help to develop new therapeutic strategies for infertility and sperm storage.

Evaluation of sperm quality and male fertility: The use of molecular markers in boar sperm and seminal plasma

In pig production, the optimization of artificial insemination (AI) efficiency significantly relies on the accurate assessment of semen quality and fertility of boars. Traditional methods such as conventional seminogram techniques, although long-standing, exhibit limited sensitivity in predicting boar fertility, warranting the exploration of novel molecular markers. This review synthesizes the current knowledge on the utilization of molecular markers for semen quality evaluation and male fertility prediction in boars, providing an in-depth examination of molecular markers in this context. Specifically, the present work delves into the potential of OMICs technologies, encompassing genetic and genomic approaches, transcriptomics, proteomics, and metabolomics. A diverse array of molecular markers, including genomic regions associated with sperm quality and male fertility, chromatin integrity, mitochondrial DNA content, mRNA and non-coding RNA signatures, as well as proteins and metabolites in sperm and seminal plasma, are identified as promising molecular markers for fertility prediction in boars. Furthermore, the need of validating biomarkers and their practical implementation in AI centres is here emphasized. Addressing these considerations and integrating molecular markers within the swine breeding field holds the potential to enhance reproductive management practices and optimize productivity in boar breeding programs. This integration can significantly improve overall efficiency within the pig breeding industry.

Genomic, transcriptomic and epigenomic analysis towards the understanding of porcine semen quality traits. Past, current and future trends

The importance of boar reproductive traits, including semen quality, in the sustainability of pig production system is increasingly being acknowledged by academic and industrial sectors. Research is needed to understand the biology and genetic components underlying these traits so that they can be incorporated into selection schemes and managerial decisions. This article reviews our current understanding of genome biology and technologies for genome, transcriptome and epigenome analysis which now facilitate the identification of causal variants affecting phenotypes more than ever before. Genetic and transcriptomic analysis of candidate genes, Genome-Wide Association Studies, expression microarrays, RNA-Seq of coding and noncoding genes and epigenomic evaluations have been conducted to profile the molecular makeups of pig sperm. These studies have provided insightful information for a several semen-related parameters. Nonetheless, this research is still incipient. The spermatozoon harbors a reduced transcriptome and highly modified epigenome, and it is assumed to be transcriptionally silent for nuclear gene expression. For this reason, the extent to which the sperm's RNA and epigenome recapitulate sperm biology and function is unclear. Hence, we anticipate that single-cell level analyses of the testicle and other male reproductive organs, which can reveal active transcription and epigenomic profiles in cells influencing sperm quality, will gain popularity and markedly advance our understanding of sperm-related traits. Future research will delve deeper into sperm fertility, boar resilience to environmental changes or harsh conditions, especially in the context of global warming, and also in transgenerational inheritance and how the environment influences the sperm transcriptome and epigenome.

Exploring the full potential of sperm function with nanotechnology tools

Sperm quality is essential to guarantee the success of assisted reproduction. However, selecting high-quality sperm and maintaining it during (cryo)preservation for high efficiency remains challenging in livestock reproduction. A comprehensive understanding of sperm biology allows for better assessment of sperm quality, which could replace conventional sperm analyses used today to predict fertility with low accuracy. Omics approaches have revealed numerous biomarkers associated with various sperm phenotypic traits such as quality, survival during storage, freezability, and fertility. At the same time, nanotechnology is emerging as a new biotechnology with high potential for use in preparing sperm intended to improve reproduction in livestock. The unique physicochemical properties of nanoparticles make them exciting tools for targeting (e.g., sperm damage and sexing) and non-targeting bioapplications. Recent advances in sperm biology have led to the discovery of numerous biomarkers, making it possible to target specific subpopulations of spermatozoa within the ejaculate. In this review, we explore potential biomarkers associated with sperm phenotypes and highlight the benefits of combining these biomarkers with nanoparticles to further improve sperm preparation and technology.

Evaluation of the effectiveness of the use of exosomes in the regulation of the mitochondrial membrane potential of frozen/thawed spermatozoa

Numerous studies confirm the involvement of extracellular vesicles (EVs) in the regulation of physiological processes of mammalian sperm cells. It has been proven that they take part in the processes of capacitation, acrosonmal reaction, and anti-oxidation. Despite growing interest in the biomedical potential (including the search for new reproductive biomarkers) of EVs, the role of extracellular seminal vesicles in maintaining semen quality during cryopreservation has not yet been established. Therefore, the objective of this experiment was to evaluate the effectiveness of the use in the regulation of the mitochondrial membrane potential of bovine sperm and to explain the mechanisms of EV action during cell cryopreservation. Exosomes were isolated from bull semen plasma, measured, and used for extender supplementation. Semen samples were collected from Simmental bulls, diluted, and pre-evaluated. Then they were divided into equal fractions that did not contain EVs or were supplemented with 0.75; 1.5 and 2.25 mg/ml of EVs. The test samples were frozen/thawed and the mitochondrial membrane potential, DNA integrity, and viability were evaluated. EVs have been established to have a positive effect on cryopreserved sperm structures. The most favourable level of EVs was 1.5 mg / ml, which can be successfully to improve cell cryostability during freezing/thawing. In this study, exosomes isolated from the sperm plasma and supplemented with a concentrated dose in the extender for sperm freezing were shown to significantly improve cryostability of cells by supporting the potentials of the mitochondrial membrane and protecting the cytoplasmic membrane of spermatozoa.