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

Investigating the impact of extracellular vesicle addition during IVM on the fertilization rate of equine oocytes following ICSI

The efficacy of in vitro embryo production (IVEP) in equines is relatively limited compared to other species due to the lack of a reliable superovulation technique, limited availability of cumulus oocyte complexes (COCs), low in vitro oocyte maturation (IVM) and fertilization rates. Extracellular vesicles (EVs), which are nanoparticles involved in intercellular signaling in the ovarian environment, have shown potential as supplements to improve oocyte development during IVM. This study tested the hypothesis that EVs from small (< 20 mm) ovarian follicles could enhance fertilization rates in mares. Follicular fluid was collected postmortem, and EVs were isolated and characterized. The IVM process was conducted with or without EVs (200 µg EV protein/ml). EV internalization during IVM was examined using fluorescent labeling and confocal microscopy. Following intracytoplasmic sperm injection (ICSI), presumptive zygotes were cultured in a time-lapse system. Confocal microscopy confirmed EV internalization by COCs. Nanoparticle tracking analysis showed that obtained EVs were submicron-sized, and flow cytometry identified surface markers CD81 and CD63 on a subpopulation of EVs. Transmission electron microscopy revealed the characteristic disk shape of EV isolates. After culture, 196 oocytes (36.84 %) exhibited a first polar body and were subjected to ICSI. The EV-treated group showed a significantly higher fertilization rate (34.7 % vs. 20.2 %; P < 0.05), reduced degeneration, and increased cleavage efficiency (P < 0.1). Despite early embryonic arrest in both groups, these results suggest that follicular fluid-derived EVs could play a supportive role in equine IVF procedures.

Follicular fluid-derived exosomal HMOX1 promotes granulosa cell ferroptosis involved in follicular atresia in geese (Anser cygnoides)

The proliferation and death of granulosa cells (GCs) in poultry play a decisive role in follicular fate and egg production. The follicular fluid (FF) contains a variety of nutrients and genetic substances to ensure the communication between follicular cells. Exosomes, as a new intercellular communication, could carry and transport the proteins, RNA, and lipids to react on GCs, which had been found in FF of various domestic animals. Whether exosomes of FF in poultry play a similar role is unclear. In this study, geese, a poultry with low egg production, were chosen, and the effect of FF exosomes on the proliferation and death of GCs was investigated. Firstly, there were not only a large number of healthy small yellow follicles (HSYFs) but also some atresia small yellow follicles (ASYFs) in the egg-laying stage. Also, the GC layers of ASYFs became loose interconnections, inward detachment, and diminished survival rate than that of HSYFs. Besides, compared to HSYFs, the contents of E2, P4, and the mRNA expression levels of ferroptosis-related genes GPX4, FPN1, and FTH1 were significantly decreased, while COX2, NCOA4, VDAC3 mRNA were significantly increased, and the structure of mitochondrial cristae disappeared and the outer membrane broke in the GC layers of ASYFs. Moreover, the ROS, MDA, and oxidation levels in the GC layers of ASYFs were significantly higher than those of HSYFs. All these hinted that ferroptosis might result in a large number of GCs death and involvement in follicle atresia. Secondly, FF exosomes were isolated from HSYFs and ASYFs, respectively, and identified by TEM, NTA, and detection of exosome marker proteins. Also, we found the exosomes were phagocytic by GCs by tracking CM-Dil. Moreover, the addition of ASYF-FF exosomes significantly elevated the MDA content, Fe2+ levels, and the mitochondrial membrane potential (MMP) in GCs, thus significantly inhibiting the proliferation of GCs, which was restored by the ferroptosis inhibitor ferrostatin-1. Thirdly, the proteomic sequencing was performed between FF-derived exosomes of HSYFs and ASYFs. We obtained 1615 differentially expressed proteins, which were mainly enriched in the protein transport and ferroptosis pathways. Among them, HMOX1 was enriched in the ferroptosis pathway based on differential protein-protein interaction network analysis. Finally, the role of HMOX1 in regulating ferroptosis in GCs was further explored. The highly expressed HMOX1 was observed in the exosomes of ASYF-FF than that in HSYF-FF. Overexpression of HMOX1 increased ATG5, LC3II, and NCOA4 expression and reduced the expression of FTH1, GPX4, PCBP2, FPN1 in the ferroptosis pathway, also promoted intracellular Fe2+ accumulation and MDA surge, which drove ferroptosis in GCs. The effects of HMOX1 on ferroptosis could be blocked by its inhibitor Znpp. Taken together, the important protein HMOX1 was identified in FF, which could be delivered to GCs via exosomes, triggering ferroptosis and thus determining the fate of follicles.

Xenogeneic Transplantation Promoted Human Exosome Sequestration in Rat Specific Organs

Purpose

Here, we aimed to study the distribution pattern of normal and cancer xenogeneic exosomes (Exos) and possible interspecies reactions in a rat model.

Methods

Exos were isolated from normal Human umbilical vein endothelial cells (HUVECs) and MDA-MB-231 breast cancer cells. Diameter size and zeta potential distribution were studied using dynamic light scattering (DLS). The morphology of isolated Exos was monitored by scanning electron microscopy (SEM) images. Using western blotting, protein levels of exosomal tetraspanins were detected. For the in vivo study, Dil-labeled normal and cancer Exos were injected into the tail vein (100 µg exosomal protein/rat) three times at 1-hour intervals. After 24 hours, rats were euthanized and the cellular uptake of Exos was monitored in different organs using immunofluorescence staining (IF).

Results

The size distribution and mean zeta potential of HUVEC and MDA-MB-231 cells Exos were 80±29.94 and 64.77±25.49 nm, and -7.58 and -11.8 mV, respectively. Western blotting revealed CD9, CD81, and CD63 in normal and cancer Exos. The SEM images exhibited typical nano-sized round-shape Exo particles. IF staining indicated sequestration of administrated Exos in splenic tissue and lungs. The distribution of Exo in kidneys, aorta, and hepatic tissue was less. These features were more evident in the group that received cancer Exos. We found no obvious adverse effects in rats that received normal or cancer Exos.

Conclusion

Normal and cancerous xenogeneic human Exos can be sequestrated prominently in splenic tissue and lungs. Novel delivery approaches and engineering tools are helpful in the target delivery of administrated Exos to the injured sites.

miRNAs in Follicular and Oviductal Fluids Support Global DNA Demethylation in Early-Stage Embryos

Global methylation levels differ in in vitro- and in vivo-developed embryos. Follicular fluid (FF) contains extracellular vesicles (EVs) containing miRNAs that affect embryonic development. Here, we examined our hypothesis that components in FF affect global DNA methylation and embryonic development. Oocytes and FF were collected from bovine ovaries. Treatment of zygotes with a low concentration of FF induced global DNA demethylation, improved embryonic development, and reduced DNMT1/3A levels. We show that embryos take up EVs containing labeled miRNA secreted from granulosa cells and the treatment of zygotes with EVs derived from FF reduces global DNA methylation in embryos. Furthermore, the methylation levels of in vitro-developed blastocysts were higher than those of in their vivo counterparts. Based on small RNA-sequencing and in silico analysis, we predicted miR-29b, -199a-3p, and -148a to target DNMTs and to induce DNA demethylation, thereby improving embryonic development. Moreover, among FF from 30 cows, FF with a high content of these miRNAs demethylated more DNA in the embryos than FF with a lower miRNA content. Thus, miRNAs in FF play a role in early embryonic development.

Extracellular Vesicles: the Next Frontier in Pregnancy Research

Extracellular vehicles (EVs) have been involved in several aspects of pregnancy, including endometrial receptivity, embryo implantation, and embryo-maternal communication showing them associated with pregnancy disorders, such as preeclampsia, gestational diabetes mellitus, and preterm birth. Further research is warranted to fully comprehend the exact pathophysiological roles of EVs and to develop new therapies targeting EVs thereby improving pregnancy outcomes. Herein, we review the recent knowledge on the multifaceted roles of EVs during pregnancy and address the majority of the molecular interactions between EVs, maternal, and fetal cells with an emphasis on disorders of pregnancy under the influence of EVs. Moreover, we also discuss its applications in clinical trials followed by prospects.

Follicular Fluid-Derived Extracellular Vesicles Influence on In Vitro Maturation of Equine Oocyte: Impact on Cumulus Cell Viability, Expansion and Transcriptome

Cumulus cell (CC) expansion is pivotal for oocyte maturation, during which CCs release factors that initiate paracrine signaling within the follicular fluid (FF). The FF is abundant in extracellular vesicles (EVs) that facilitate intercellular communication. Although bovine and murine EVs can control cumulus expansion, these effects have not been observed in equines. This study aimed to assess the impact of FF-derived EVs (ffEVs) on equine CC expansion, viability, and transcriptome. Cumulus-oocyte complexes (COCs) that underwent in vitro maturation (IVM) in the presence (200 µg protein/mL) or absence (control) of ffEVs were assessed for cumulus expansion and viability. CCs were isolated after 12 h of IVM, followed by RNA extraction, cDNA library generation, and subsequent transcriptome analysis using next-generation sequencing. Confocal microscopy images illustrated the internalization of labeled ffEVs by CCs. Supplementation with ffEVs significantly enhanced cumulus expansion in both compacted (Cp, p < 0.0001) and expanded (Ex, p < 0.05) COCs, while viability increased in Cp groups (p < 0.01), but decreased in Ex groups (p < 0.05), compared to the controls. Although transcriptome analysis revealed a subtle effect on CC RNA profiles, differentially expressed genes encompassed processes (e.g., MAPK and Wnt signaling) potentially crucial for cumulus properties and, consequently, oocyte maturation.

Exosomes as Theranostic Agents in Reproduction System

Exosomes (Exos), belonging to extracellular vesicles, are cell-derived nano-sized vesicles with the potential to carry different kinds of biological molecules. Many studies have proved the impacts of exosomal cargo on several biological processes in female and male reproductive systems. It is also hypothesized that changes in exosomal cargo are integral to the promotion of certain pathological conditions, thus Exos can be used as valid biomarkers for the diagnosis of infertility and other abnormal conditions. Here, efforts are made to collect some recent data related to the physiological significance of Exos in the reproductive system, and their potential therapeutic effects. It is anticipated that the current review article will lay the groundwork for elucidating the source and mechanisms by which Exos control the reproductive system additionally supplying fresh methods and concepts for the detection and treatment of disorders associated with fertility for future studies.

Prokaryotic microvesicles Ortholog of eukaryotic extracellular vesicles in biomedical fields

Every single cell can communicate with other cells in a paracrine manner via the production of nano-sized extracellular vesicles. This phenomenon is conserved between prokaryotic and eukaryotic cells. In eukaryotic cells, exosomes (Exos) are the main inter-cellular bioshuttles with the potential to carry different signaling molecules. Likewise, bacteria can produce and release Exo-like particles, namely microvesicles (MVs) into the extracellular matrix. Bacterial MVs function with diverse biological properties and are at the center of attention due to their inherent therapeutic properties. Here, in this review article, the comparable biological properties between the eukaryotic Exos and bacterial MVs were highlighted in terms of biomedical application. Video Abstract.

Characteristics of size-exclusion chromatography enriched porcine follicular fluid extracellular vesicles

Extracellular vesicles (EVs) are membrane-bound nanoparticles that are released by different cell types and play a crucial role in the intercellular communication. They carry various biomolecular compounds such as DNA, RNA, proteins, and lipids. Given that EVs are a new element of the communication within the ovarian follicle, extensive research is needed to optimize method of their isolation. The aim of the study was to assess size-exclusion chromatography (SEC) as a tool for effective EVs isolation from porcine ovarian follicular fluid. The characterization of EVs was performed by nanoparticle tracking analysis, transmission electron microscopy, atomic force microscopy, mass spectrometry and Western blot. We determined EVs concentration, size distribution, zeta potential, morphology, purity, and marker proteins. Our results show that SEC is an effective method for isolation of EVs from porcine follicular fluid. They displayed predominantly exosome properties with sufficient purity and possibility for further functional analyses, including proteomics.

A crucial exosome-related gene pair (AAMP and ABAT) is associated with inflammatory cells in intervertebral disc degeneration

Identification of exosome-related genes (ERGs) and competing endogenous RNAs (ceRNAs) associated with intervertebral disc degeneration (IDD) may improve its diagnosis and reveal its underlying mechanisms. We downloaded 49 samples from Gene Expression Omnibus and identified candidate ERGs using differentially expressed ERGs (De-ERGs), exosome-related gene pairs (ERGPs), and machine learning algorithms [least absolute shrinkage and selection operator (LASSO) and support vector machine (SVM)]. Immune cell-related ERGs were selected via immune-infiltration analysis, and clinical values were assessed using receiver operating characteristic curves. Based on the De-ERGs, a ceRNA network comprising 1,512 links and 330 nodes was constructed and primarily related to signal transduction pathways, apoptosis-related biological processes, and multiple kinase-related molecular functions. In total, two crucial De-ERGs [angio-associated migratory cell protein (AAMP) and 4-aminobutyrate aminotransferase (ABAT)] were screened from results in De-ERGs, ERGPs, LASSO, and SVM. Increased AAMP expression and decreased ABAT expression were positively and negatively correlated with CD8⁺ T cell infiltration, respectively. AAMP/ABAT was the only pair differentially expressed in IDD and correlated with CD8⁺ T cell infiltration. Furthermore, AAMP/ABAT displayed higher accuracy in predicting IDD than individual genes. These results demonstrated the ERGP AAMP/ABAT as a robust signature for identifying IDD and associated with increased CD8⁺ T cell infiltration, suggesting it as a promising IDD biomarker.

Follicular fluid extracellular vesicle miRNAs and ovarian aging

The decrease in the reproductive potential due to aging occurs as a gradual decline in the quantity and quality of the ovarian reserve, a phenomenon associated with risk of miscarriage, pregnancy loss, low ovarian stimulation, and oocyte abnormalities, such as chromosomal aneuploidies. Numerous studies have shown that the fertility potential of older women is decreased by changes to the cellular composition of the follicles. Additionally, a unique method of cellular communication has been identified which involves the release of extracellular vesicles (EVs) in various body fluids including follicular fluid (FF). The changing composition of EVs especially non-coding RNAs, such as miRNAs has been documented across a broad range of cell types during aging. Accordingly, alterations of miRNA cargo within FF-derived EVs due to increased age may serve as a potential predictor of oocyte quality. In this review we examine the relationship between FF EV miRNAs and ovarian aging.

Exosomes - Spectacular role in reproduction

Exosomes are nano-sized structures that are found in semen, epididymal -fluid, endometrium, as well as in follicular fluid. They are responsible for transporting bioactive cargo- proteins, lipids, and nucleic acids. Exosomes have been proven to influence processes in both female and male reproductive systems, including gametogenesis, acrosomal reaction, sperm capacitation, and embryo implantation in the endometrium. Exosomes are made of the same particles as the cells they come from and are secreted by normal and pathological cells. Therefore, exosomes can reflect the physiological state of cells. Moreover, due to the transportation of biomolecules, they participate in intercellular communication and can be used as biomarkers of many diseases, including ovarian, endometrial and prostate cancer. Identification of exosomes as biomarkers could contribute to a better understanding of genital dysfunction and fertility disorders.

Exosomes as Naturally Occurring Vehicles for Delivery of Biopharmaceuticals: Insights from Drug Delivery to Clinical Perspectives

Exosomes as nanosized vesicles are emerging as drug delivery systems for therapeutics owing to their natural origin, their ability to mediate intercellular communication, and their potential to encapsulate various biological molecules such as proteins and nucleic acids within the lipid bilayer membrane or in the lumen. Exosomes contain endogenous components (proteins, lipids, RNA) that could be used to deliver cargoes to target cells, offering an opportunity to diagnose and treat various diseases. Owing to their ability to travel safely in extracellular fluid and to transport cargoes to target cells with high efficacy, exosomes offer enhanced delivery of cargoes in vivo. However, several challenges related to the stabilization of the exosomes, the production of sufficient amounts of exosomes with safety and efficacy, the efficient loading of drugs into exosomes, the clearance of exosomes from circulation, and the transition from the bench scale to clinical production may limit their development and clinical use. For the clinical use of exosomes, it is important to understand the molecular mechanisms behind the transport and function of exosome vesicles. This review exploits techniques related to the isolation and characterization of exosomes and their drug delivery potential to enhance the therapeutic outcome and stabilization methods. Further, routes of administration, clinical trials, and regulatory aspects of exosomes will be discussed in this review.

Amniotic fluid-derived exosomes improved spermatogenesis in a rat model of azoospermia

AIMS

This study aimed to explore the therapeutic effects of amniotic fluid-derived extracellular vesicles including exosomes (AF-Exos) on the recovery of sperm production capacity in a rat model of azoospermia.

MAIN METHODS

The non-obstructive azoospermia (NOA) was induced in rats using intratesticular administration of Busulfan. Azoospermia was confirmed by testis histology. AF-Exos samples containing 10 or 40 μg exosomal proteins were injected into testicular tissue of NOA rats. After two months, the recovery of spermatogenesis was monitored via histopathological staining, spermiogram, and hormonal analysis. Immunohistochemistry staining for OCT-3/4 was used to identify of spermatogonial progenitors. The expression of DAZL and VASA, was also measured.

KEY FINDINGS

AF-Exos exhibited sphere-shaped morphology with the mean diameter and zeta potential of 50 ± 7.521 nm and -7.16 mV. Immunoblots revealed that isolated nanoparticles were CD63, CD9, and CD81 positive. Histopathological evaluation revealed that spermatogenesis was improved significantly in NOA rats after AF-Exos injection. Data showed that the sperm parameters and spermatogenesis index were significantly improved after AF-Exos injection compared to azoospermic groups. OCT-3/4⁺ cells were increased in NOA rats after AF-Exos injection, showing the restoration of spermatogenesis. In the present study, both doses of exosome (10 and 40 μg) restored the testicular function of NOA rats. DAZL and VASA were increased significantly in animals who received 40 μg exosomal protein compared to azoospermic rats. Except in a high dose of AF-Exos (40 μg) for Testosterone and FSH, no statistically significant differences were found regarding hormones post-exosome injection.

SIGNIFICANCE

Our study demonstrated that AF-Exos regenerated spermatogenesis and improved sperm quality in NOA rats.

Identification of an extracellular vesicle-related gene signature in the prediction of pancreatic cancer clinical prognosis

Although extracellular vesicles (EVs) in body fluid have been considered to be ideal biomarkers for cancer diagnosis and prognosis, it is still difficult to distinguish EVs derived from tumor tissue and normal tissue. Therefore, the prognostic value of tumor-specific EVs was evaluated through related molecules in pancreatic tumor tissue. NA sequencing data of pancreatic adenocarcinoma (PAAD) were acquired from The Cancer Genome Atlas (TCGA) and International Cancer Genome Consortium (ICGC). EV-related genes in pancreatic cancer were obtained from exoRBase. Protein–protein interaction (PPI) network analysis was used to identify modules related to clinical stage. CIBERSORT was used to assess the abundance of immune and non-immune cells in the tumor microenvironment. A total of 12 PPI modules were identified, and the 3-PPI-MOD was identified based on the randomForest package. The genes of this model are involved in DNA damage and repair and cell membrane-related pathways. The independent external verification cohorts showed that the 3-PPI-MOD can significantly classify patient prognosis. Moreover, compared with the model constructed by pure gene expression, the 3-PPI-MOD showed better prognostic value. The expression of genes in the 3-PPI-MOD had a significant positive correlation with immune cells. Genes related to the hypoxia pathway were significantly enriched in the high-risk tumors predicted by the 3-PPI-MOD. External databases were used to verify the gene expression in the 3-PPI-MOD. The 3-PPI-MOD had satisfactory predictive performance and could be used as a prognostic predictive biomarker for pancreatic cancer.

Effectiveness of Stem Cell Therapy in the Treatment of Ovarian Disorders and Female Infertility: A Systematic Review

BACKGROUND

Infertility is a major problem worldwide. Various strategies are being used to develop better treatments for infertility and The most trending strategy is the stem cell therapy. In this study, the literature on stem cell therapy for ovarian disorders is summarized with analysis of current developments.

OBJECTIVE

Different published studies on stem cell-based therapy for the treatment of various types of ovarian insufficiency and disorders such as Premature Ovarian Insufficiency (POI) in the affected female population in animal or human clinical studies are systematically reviewed.

METHODS

We monitored five databases, including PubMed, Cochrane, Embase, Scopus, and ProQuest. A comprehensive online search was done using the criteria targeting the application of stem cells in animal models for menopause. Two independent reviewers carefully evaluated titles and abstracts of studies. The stem cell type, source, dosage, route of administration were highlighted in various POI animals models. Non-relevant and review articles were excluded.

OUTCOMES

648 published studies were identified during the initial comprehensive search process from which 41 were selected according to designed criteria. Based on our analysis, stem cells could accelerate ovarian tissues rejuvenation, regulate systemic sex-related hormones levels and eventually increase fertility rate.

CONCLUSION

The evidence suggests that stem cell-based therapies could be considered as an alternative modality to deal with women undergoing POI.

Extracellular Vesicles: Recent Developments in Aging and Reproductive Diseases

Extracellular vesicles (EVs), present in cell culture media and several body fluids, play a prominent role in intercellular communication under physiological and pathological conditions. We performed a systematic literature search to review evidence regarding the existence, composition, and release of different EVs, as well as the biomarkers, cargos, and separation methods. We also reviewed the potential of EVs to transport cargos and alter the function and phenotype of recipient cells associated with aging and reproductive diseases, including polycystic ovary syndrome and endometriosis. In aging, EVs promote inflammatory reactions and offsetting the occurrence of aging. In the polycystic ovary syndrome and endometriosis, EVs and their cargos are involved in the occurrence of diseases, therapeutic strategies, and perform as non-invasive biomarkers. As the study of EVs is still in the early stages, it is not surprising that most of the current literature only describes their possible roles.

Exosomes as Messengers Between Mother and Fetus in Pregnancy

The ability of exosomes to transport different molecular cargoes and their ability to influence various physiological factors is already well known. An exciting area of research explores the functions of exosomes in healthy and pathological pregnancies. Placenta-derived exosomes were identified in the maternal circulation during pregnancy and their contribution in the crosstalk between mother and fetus are now starting to become defined. In this review, we will try to summarize actual knowledge about this topic and to answer the question of how important exosomes are for a healthy pregnancy.

Mesenchymal Stem/Stromal Cell-Derived Exosomes for Immunomodulatory Therapeutics and Skin Regeneration

Exosomes are nano-sized vesicles that serve as mediators for cell-to-cell communication. With their unique nucleic acids, proteins, and lipids cargo compositions that reflect the characteristics of producer cells, exosomes can be utilized as cell-free therapeutics. Among exosomes derived from various cellular origins, mesenchymal stem cell-derived exosomes (MSC-exosomes) have gained great attention due to their immunomodulatory and regenerative functions. Indeed, many studies have shown anti-inflammatory, anti-aging and wound healing effects of MSC-exosomes in various in vitro and in vivo models. In addition, recent advances in the field of exosome biology have enabled development of specific guidelines and quality control methods, which will ultimately lead to clinical application of exosomes. This review highlights recent studies that investigate therapeutic potential of MSC-exosomes and relevant mode of actions for skin diseases, as well as quality control measures required for development of exosome-derived therapeutics.

Autologous mitochondrial microinjection; a strategy to improve the oocyte quality and subsequent reproductive outcome during aging

Along with the decline in oocyte quality, numerous defects such as mitochondrial insufficiency and the increase of mutation and deletion have been reported in oocyte mitochondrial DNA (mtDNA) following aging. Any impairments in oocyte mitochondrial function have negative effects on the reproduction and pregnancy outcome. It has been stated that infertility problems caused by poor quality oocytes in women with in vitro fertilization (IVF) and repeated pregnancy failures are associated with aging and could be overcome by transferring large amounts of healthy mitochondria. Hence, researches on biology, disease, and the therapeutic use of mitochondria continue to introduce some clinical approaches such as autologous mitochondrial transfer techniques. Following mitochondrial transfer, the amount of ATP required for aged-oocyte during fertilization, blastocyst formation, and subsequent embryonic development could be an alternative modality. These modulations improve the pregnancy outcome in women of high reproductive aging as well. In addition to overview the clinical studies using mitochondrial microinjection, this study provides a framework for future approaches to develop effective treatments and preventions of congenital transmission of mitochondrial DNA mutations/diseases to offspring. Mitochondrial transfer from ovarian cells and healthy oocytes could lead to improved fertility outcome in low-quality oocytes. The modulation of mitochondrial bioactivity seems to regulate basal metabolism inside target oocytes and thereby potentiate physiological activity of these cells while overcoming age-related infertility in female germ cells.

Evaluation of the association between exosomal levels and female reproductive system and fertility outcome during aging: a systematic review protocol

BACKGROUND

Exosomes may have critical roles in the maternal-embryo cross-talk for the recognition and maintenance of pregnancy during maternal aging. Exosomes have the capability to carry developmental signaling molecules with the ability to modulate gene expressions and affect growth and regulation of embryo during pregnancy. Systematic review aims to evaluate age-related alterations in the exosomal content and functions that can influence the reproductive performance in human and animal models as conveyors of senescence signals.

METHODS

A literature search of electronic databases including MEDLINE (PubMed), Embase, ProQuest, Scopus, Google Scholar, WHO, SID, MAGIRAN, and Barakat will be conducted. Following the online search, articles will be screened by two independent reviewers according to inclusion and exclusion criteria. Eligible studies will be critically appraised by reviewers at the study level for methodological quality using Joanna Briggs Institute's standardized critical appraisal tools. The extracted data from selected studies will cover the study populations, methods, current evidence about the physiological role of extracellular vesicles and exosomes in reproductive system, relevant outcomes, and possible conclusions about the effectiveness of exposure.

DISCUSSION

Regarding the role of exosomes and their cargoes in the function of reproductive tract, the possible beneficial or adverse effects following exosomal administration from younger women to older women will be evaluated in the systematic review. As a result, exosome therapy could be suggested as a novel therapeutic agent if the favorable results are identified.

Intrafollicular barriers and cellular interactions during ovarian follicle development

Follicles are composed of different interdependent cell types including oocytes, cumulus, granulosa, and theca cells. Follicular cells and oocytes exchange signaling molecules from the beginning of the development of the primordial follicles until the moment of ovulation. The follicular structure transforms during folliculogenesis; barriers form between the germ and the somatic follicular cells, and between the somatic follicular cells. As such, communication systems need to adapt to maintain the exchange of signaling molecules. Two critical barriers are established at different stages of development: the zona pellucida, separating the oocyte and the cumulus cells limiting the communication through specific connections, and the antrum, separating subpopulations of follicular cells. In both situations, communication is maintained either by the development of specialized connections as transzonal projections or by paracrine signaling and trafficking of extracellular vesicles through the follicular fluid. The bidirectional communication between the oocytes and the follicle cells is vital for driving folliculogenesis and oogenesis. These communication systems are associated with essential functions related to follicular development, oocyte competence, and embryonic quality. Here, we discuss the formation of the zona pellucida and antrum during folliculogenesis, and their importance in follicle and oocyte development. Moreover, this review discusses the current knowledge on the cellular mechanisms such as the movement of molecules via transzonal projections, and the exchange of extracellular vesicles by follicular cells to overcome these barriers to support female gamete development. Finally, we highlight the undiscovered aspects related to intrafollicular communication among the germ and somatic cells, and between the somatic follicular cells and give our perspective on manipulating the above-mentioned cellular communication to improve reproductive technologies.