Cell-secreted vesicles containing microRNAs as regulators of gamete maturation

Proteomic analysis reveals the negative modulator of sperm function glycodelin as over-represented in semen exosomes isolated from asthenozoospermic patients

STUDY QUESTION

Are there differences in the proteomic profile of exosomes isolated from seminal plasma of normozoospermic (NSP) and severe asthenozoospermic (SA) men, potentially contributing to sperm features?

SUMMARY ANSWER

A relevant group of proteins known to positively regulate sperm functions were over-represented in seminal exosomes of NSP men, i.e. cysteine-rich secretory protein-1 (CRISP1), while the inhibitory protein glycodelin was enriched in exosomes of SA subjects.

WHAT IS KNOWN ALREADY

Exosomes are secreted along the male reproductive tract and are thought to be involved in spermatozoa maturation and function. Ejaculated spermatozoa are still able to capture exosomes; exosomes of NSP individuals improve sperm motility and prompt capacitation, while exosomes of SA men fail to exert similar features.

STUDY DESIGN, SIZE, DURATION

Semen samples from NSP and SA men, aged 18 to 55 and registered at a single IVF center, were considered for this study project. Subjects were subdivided into three groups: a discovery cohort (five NSP men and six SA patients), a validation cohort (seven NSP and seven SA men) and the ‘glycodelin analysis’ cohort (20 NSP and 37 SA men). Exosomes were purified from semen of every participant.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Exosomes were characterized by nanoparticle tracking analysis, transmission electron microscopy and western blot. Comprehensive proteomics analysis of the exosomal proteome was performed by nanoscale liquid chromatographic tandem mass spectrometry analysis. Funrich software was used to determine statistical enrichment of pathways, networks and Gene Ontology terms of the identified proteins. Validation of differentially expressed proteins was performed through ELISA and western blot analysis.

MAIN RESULTS AND THE ROLE OF CHANCE

The comprehensive proteomic analysis identified a total of 2138 proteins for both groups. There were 89 proteins found to be differentially expressed in exosomes of NSP versus SA subjects, of which 37 were increased in the NSP group and 52 were increased in the SA group. One-third of the exosomes-associated proteins highly expressed in NSP samples were involved in the reproductive process; conversely, the over-expressed proteins in exosomes of SA samples were not functionally specific. Quantitative data were confirmed on seminal exosomes from different cohorts of subjects.

LARGE SCALE DATA

N/A

LIMITATIONS, REASONS FOR CAUTION

Transfer of the proteins from exosomes to spermatozoa has been only partially demonstrated and up-take mechanisms are still poorly defined.

WIDER IMPLICATIONS OF THE FINDINGS

Seminal exosomes carry proteins that are potentially able to either favour or inhibit the reproductive process in humans. A better understanding of these phenomena might pave the way for novel intervention measures in terms of male infertility.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by the Italian Ministry of Health through an Institution Seed Grant. None of the authors has any competing interests.

Extracellular Vesicles in Human Oogenesis and Implantation

Reproduction, the ability to generate offspring, represents one of the most important biological processes, being essential for the conservation of the species. In mammals, it involves different cell types, tissues and organs, which, by several signaling molecules, coordinate the different events such as gametogenesis, fertilization and embryo development. In the last few years, the role of Extracellular Vesicles, as mediators of cell communication, has been investigated in every phase of these complex processes. Microvesicles and exosomes, identified in the fluid of ovarian follicles during egg maturation, are involved in communication between the developing oocyte and the somatic follicular cells. More recently, it has been demonstrated that, during implantation, Extracellular Vesicles could participate in the complex dialog between the embryo and maternal tissues. In this review, we will focus our attention on extracellular vesicles and their cargo in human female reproduction, mainly underlining the involvement of microRNAs in intercellular communication during the several phases of the reproductive process.

Physiological impact of extracellular vesicles on female reproductive system; highlights to possible restorative effects on female age-related fertility

An alternative mechanism of cell-to-cell communication via extracellular vesicles (EVs) has recently raised increasing attention. EVs are spherical structures comprising exosomes and microvesicles, capable of transferring regulatory molecules and genetic information from one cell to another. EVs act as modulators which can alter a wide spectrum of functions at the cellular level in the recipient cells, taking part in a variety of biological processes in both physiological and pathological conditions. Alteration in EVs content, notably exosomes, was reported during cellular senescence and in patients with age-related diseases. Most studies reported regulating the impacts of exosomes on fertility and pregnancy outcomes via their capability in carrying developmental signaling molecules like proteins, RNA cargos, influencing gene expressions, affecting growth, and development of embryos during aging. Alterations in the exosomal content and functions can influence the reproductive performance in human and animals as conveyors of senescence signals from outside of the cells. This review aimed to summarize evidence on the role of EVs on modulating fertility, early embryonic development, maternal-embryo crosstalk for the recognition, and maintenance of pregnancy during maternal aging. Advanced clinical studies are required to strengthen the findings that the benefit of exosomes can be extended to subjects undergoing reproductive aging. © 2019 BioFactors, 45(3):293-303, 2019.

Adverse effects of paternal obesity on the motile spermatozoa quality

Growing evidence suggests that paternal obesity may decrease male fertility potential. During infertility treatment with intra-cytoplasmic sperm injection (ICSI), a morphologically normal motile spermatozoon is injected into a mature egg, when possible. However, sperm motility and morphology per se do not reflect the sperm molecular composition. In this study, we aimed to assess the quality of motile spermatozoa in the context of obesity by analysing their conventional and molecular characteristics as well as their ability to promote early embryonic development. A prospective study was conducted on 128 infertile men divided into three groups: 40 lean, 42 overweight, and 46 obese men. Conventional sperm parameters (concentration, motility and morphology) and sperm molecular status (chromatin composition and integrity, 5-methycytosine (5-mC) and 5-hydroxycytosine (5-hmC) contents and oxidative stress level) were analysed on raw semen and/or on motile spermatozoa selected by density gradient or swim-up techniques. Morphokinetic analysis of the embryos derived from ICSI was performed using the Embryoviewer software. Our results showed that the motile sperm-enriched fraction from obese men exhibited higher levels of retained histones (p<0.001), elevated percentage of altered chromatin integrity (p<0.001), and decreased contents of 5-hmC (p<0.001), and 5-mC (p<0.05) levels as compared to that from lean men. Importantly, there were no statistically significant correlations between these molecular parameters and the percentages of morphologically normal motile spermatozoa. Regarding embryo morphokinetics, the CC1 (p<0.05) and CC3 (p<0.05) embryonic cell cycles were significantly delayed in the cleavage embryos of the obese group as compared to the embryos of the lean group. Our data is of particular interest because, besides demonstrating the negative impacts of obesity on motile spermatozoa molecular composition, it also highlights the possible risk of disturbing early embryonic cell cycles kinetics in the context of paternal obesity.

Embryotrophic effects of extracellular vesicles derived from outgrowth embryos in pre- and peri-implantation embryonic development in mice

Recently, many studies have investigated the role of extracellular vesicles (EVs) on reproductive events, including embryo development and death, oviduct-embryo crosstalk, in vitro fertilization and others. The aim of this study was to demonstrate whether outgrowth embryo-derived EVs function as bioactive molecules and regulate mouse embryonic developmental competence in vitro and implantation potential in utero. The EVs from mouse outgrowth embryos on 7.5 days postcoitum were detected and selectively isolated to evaluate the embryotrophic functions on preimplantation embryos. Developmental outcomes such as the percentage of blastocyst formation, hatching, and trophoblastic outgrowth were assessed. Furthermore, the total cell number and apoptotic index of blastocysts, which were incubated with EVs during the culture period, were evaluated by fluorescence microscopy. Implantation potential in utero was investigated following embryo transfer. The EVs from outgrowth embryo-conditioned media have rounded membrane structures that range in diameter from 20 to 225 nm. Incubation with EVs improved preimplantation embryonic development by increasing cell proliferation and decreasing apoptosis in blastocysts. Moreover, the implantation rates following embryo transfer were significantly higher in EV-supplemented embryos compared with the control. Collectively, EVs from outgrowth embryo could enhance the embryonic developmental competence and even implantation potential in mice.

Updating the markers for oocyte quality evaluation: intracellular temperature as a new index

BACKGROUND

The developmental competence of an embryo is principally dictated by the oocyte. Usually, oocyte selection is based on morphological properties; however, all morphological criteria that are currently used for the grading and screening of oocytes are not able to eliminate the subjectivity. Despite recent studies of the molecular factors related to oocyte quality, it is technically difficult to develop an index based on these factors, and new indices that reflect intracellular conditions are necessary.

METHODS

Morphological and molecular factors influencing developmental competence were comprehensively reviewed, and intracellular temperature was evaluated as a new marker of oocyte quality.

MAIN FINDINGS

The intracellular temperature of mature oocytes was high in fresh oocytes and decreased with time after polar body release. Under the same conditions, the intracellular temperature and its distribution differed among oocytes, suggesting that temperature represents the state of each oocyte.

CONCLUSION

Intracellular temperature is advantageous as an objective and quantitative indicator of oocyte quality. Further studies should evaluate the link between temperature and cellular phenomena to establish its use as an indicator of quality.

Leukemia cell-derived microvesicles induce T cell exhaustion via miRNA delivery

T cell function in cancer patients is usually impaired due to the constitutive activation of immune checkpoint inhibitors. This state is known as 'exhaustion' and is often associated with the inefficient control of tumors or persistent infections. In this work, we investigated the role of leukemia cell-derived microvesicles (MVs) in T cell exhaustion. Following incubation with MVs from various sources, all T cell subtypes exhibited the exhaustion phonotype and impaired cytokine secretion in vitro. Mice models also showed the connection between immune checkpoint inhibitors and MV injection. Sequencing and bioinformatics analyses indicated that a number of transcription factors and microRNAs (miRNAs) were attributable to the dysregulation of pathways and exhaustion in T cells. Further work revealed that functional miR-92a-3p, miR-21-5p, miR-16-5p, miR-126 and miR-182-5p in MVs could be delivered into T cells to induce the exhaustion phenotype. SerpinB2, IL-1β and CXCL5, which are mediators of the NF-κB pathway, were identified as the targets of the miRNAs mentioned above. We demonstrated that leukemia-derived MVs could initiate T cell exhaustion via the progressive temporal delivery of multiple exogenous miRNAs into T cells and the subsequent interaction of these miRNAs with their targets. Therefore, MVs can be expected not only to become new indicators of the T cell status in patients but also to be used as novel targets for personalized patient treatment.