Discrimination between exosomes and HIV-1: purification of both vesicles from cell-free supernatants

Characterization, microRNA profiling, and immunomodulatory role of plasma-derived exosomes from olive flounder (Paralichthys olivaceus) in response to viral hemorrhagic septicemia virus

Viral hemorrhagic septicemia virus (VHSV) is a highly pathogenic virus that frequently infects olive flounder (Paralichthys olivaceus), causing viral hemorrhagic septicemia (VHS), and posing a significant threat to global aquaculture. This study characterizes plasma-derived exosomes from olive flounder following VHSV challenge (VHSV-Exo) or phosphate buffered saline (PBS) injection (PBS-Exo), comparing their morphology, physicochemical properties, molecular profiles, and immunomodulatory functions. Both PBS-Exo (118.3 ± 8.6 nm) and VHSV-Exo (82.6 ± 5.9 nm) exhibited the typical cup-shaped morphology of exosomes. The successful isolation and purity of exosomes were confirmed by the presence of exosome markers (CD81, CD9, and CD63) and the absence of albumin. High-throughput sequencing identified 13 differentially expressed (DE) microRNAs (miRNAs) between PBS-Exo and VHSV-Exo, including six upregulated and seven downregulated miRNAs (log2 fold change ≥1 or ≤ -1). Toxicity assessments revealed that neither PBS-Exo nor VHSV-Exo were toxic to murine macrophage Raw 264.7 cells or zebrafish larvae at tested doses (up to 100 and 400 μg/mL, respectively). The absence of green fluorescence at 96 h post-treatment of VHSV-Exo indicated minimal reactive oxygen species generation, further supporting exosome safety. Functional studies demonstrated that both in vitro (Raw 264.7 cells) and in vivo (adult zebrafish) treatments with exosomes regulated immune-related genes and proteins expression. Notabaly, VHSV-Exo exhibited superior immunomodulatory effects, as evidenced by enhanced immune gene and protein expression. To our knowledge, this is the first study demonstrating the immunomodulatory potential of VHSV-Exo. These findings highlight VHSV-Exo as a promising immunomodulatory agent, with potential applications as a prophylactic vaccine candidate against VHSV infection in aquaculture.

Trojan Horse-Like Vehicles for CRISPR-Cas Delivery: Engineering Extracellular Vesicles and Virus-Like Particles for Precision Gene Editing in Cystic Fibrosis

The advent of genome editing has kindled the hope to cure previously uncurable, life-threatening genetic diseases. However, whether this promise can be ultimately fulfilled depends on how efficiently gene editing agents can be delivered to therapeutically relevant cells. Over time, viruses have evolved into sophisticated, versatile, and biocompatible nanomachines that can be engineered to shuttle payloads to specific cell types. Despite the advances in safety and selectivity, the long-term expression of gene editing agents sustained by viral vectors remains a cause for concern. Cell-derived vesicles (CDVs) are gaining traction as elegant alternatives. CDVs encompass extracellular vesicles (EVs), a diverse set of intrinsically biocompatible and low-immunogenic membranous nanoparticles, and virus-like particles (VLPs), bioparticles with virus-like scaffold and envelope structures, but devoid of genetic material. Both EVs and VLPs can efficiently deliver ribonucleoprotein cargo to the target cell cytoplasm, ensuring that the editing machinery is only transiently active in the cell and thereby increasing its safety. In this review, we explore the natural diversity of CDVs and their potential as delivery vectors for the clustered regularly interspaced short palindromic repeats (CRISPR) machinery. We illustrate different strategies for the optimization of CDV cargo loading and retargeting, highlighting the versatility and tunability of these vehicles. Nonetheless, the lack of robust and standardized protocols for CDV production, purification, and quality assessment still hinders their widespread adoption to further CRISPR-based therapies as advanced "living drugs." We believe that a collective, multifaceted effort is urgently needed to address these critical issues and unlock the full potential of genome-editing technologies to yield safe, easy-to-manufacture, and pharmacologically well-defined therapies. Finally, we discuss the current clinical landscape of lung-directed gene therapies for cystic fibrosis and explore how CDVs could drive significant breakthroughs in in vivo gene editing for this disease.

Navigating the Purification Process: Maintaining the Integrity of Replication-Competent Enveloped Viruses

Replication-competent virus particles hold significant therapeutic potential in application as oncolytic viruses or cancer vaccines. Ensuring the viral integrity of these particles is crucial for their infectivity, safety, and efficacy. Enveloped virus particles, in particular, offer large gene insert capacities and customizable target specificity. However, their sensitivity to environmental factors presents challenges in bioprocessing, potentially compromising high quality standards and cost-effective production. This review provides an in-depth analysis of the purification process steps for replication-competent enveloped virus particles, emphasizing the importance of maintaining viral integrity. It evaluates bioprocessing methods from cell culture harvest to final sterile filtration, including centrifugation, chromatographic, and filtration purification techniques. Furthermore, the manuscript delves into formulation and storage strategies necessary to preserve the functional and structural integrity of virus particles, ensuring their long-term stability and therapeutic efficacy. To assess the impact of process steps on particles and determine their quality and integrity, advanced analytical methods are required. This review evaluates commonly used methods for assessing viral integrity, such as infectious titer assays, total virus particle quantification, and structural analysis. By providing a comprehensive overview of the current state of bioprocessing for replication-competent enveloped virus particles, this review aims to guide researchers and industry professionals in developing robust and efficient purification processes. The insights gained from this analysis will contribute to the advancement of virus-based therapeutics, ultimately supporting the development of safe, effective, and economically viable treatments for various diseases.

Comparing methods to detect cellular proteins on the surface of HIV-1 virions

The surface of HIV-1 is embedded with numerous host-derived proteins. Characterizing these proteins can enhance knowledge of virus biology and potentially identify novel therapeutic targets. As many of these proteins are present in low abundance on virion surfaces, their identification can be hindered by inherent variables in the methods employed to detect them, including their varying assay sensitivities, sample processing, quantitative capacity, and experimental reproducibility. Here, we have compared the quantification of virion-incorporated proteins using conventional virus immunocapture assays and western blotting, alongside an emerging technique called flow virometry (FV). Using four different pseudovirus models that each express a human protein of interest (CD14, CD38, CD59 and CD162), we compared four experimental techniques for their ability to reliably quantify the incorporation of those four proteins onto virion surfaces. Our results shed light on the advantages and caveats of each technique for detecting virion-incorporated proteins and highlight the breadth in quantification for each technique under different experimental conditions. Protein detection with (FV) provided distinct advantages as it enabled highly reproducible quantifications, had the lowest sample requirements and reagent costs, and minimal hands-on experimental time. We additionally highlight some important considerations in experimental design when studying virion-incorporated proteins, such as the effect of different antibody clones, assay incubation times, and contributions of extracellular vesicles. Most importantly, our data illustrate the importance of using a combination of orthogonal approaches to detect virus-associated proteins, to enable reliable and reproducible quantification that accounts for individual assay biases.

Exploring the relationship between extracellular vesicles, the dendritic cell immunoreceptor, and microRNA-155 in an in vivo model of HIV-1 infection to understand the disease and develop new treatments

HIV-1 infection induces persistent immune system activation despite antiretroviral therapy. New immunomodulatory targets might be required to restore immune competence. The dendritic cells immunoreceptor (DCIR) can bind HIV-1 and regulate immune functions and extracellular vesicles (EVs) production. EVs have emerged as biomarkers and a non-invasive tool to monitor HIV-1 progression. In people living with HIV-1, an increase in the size and abundance of EVs is associated with a decline in the CD4/CD8 T cells ratio, a key marker of immune dysfunction. Analysis of host nucleic acids within EVs has revealed an enrichment of microRNA-155 (miR-155) during HIV-1 infection. Experiments have demonstrated that miR-155-rich EVs enhance HIV-1 infection in vitro. A humanized NSG-mouse model was established to assess the in vivo impact of miR-155-rich EVs. Co-production of the virus with miR-155-rich EVs heightened the viral load and lowered the CD4/CD8 ratio in the mice. Upon euthanasia, EVs were isolated from plasma for size and quantity assessment. Consistent with findings in individuals with HIV-1, increased EV size and abundance were inversely correlated with the CD4/CD8 ratio. Next, by using the virus co-product with EV-miR-155, we tested a DCIR inhibitor to limit infection and immune damage in a humanized mouse model. DCIR inhibition reduced infection and partially restored immune functions. Finally, viral particles and various EV subtypes can convey HIV-1 RNA. HIV-1 RNA was predominantly associated with large EVs (200-1000 nm) rather than small EVs (50-200 nm). Viral loads in large EVs strongly correlated with blood and tissue markers of immune activation. The humanized mice model has proven its applicability to studying the roles of EVs on HIV-1 infection and investigating the impact of DCIR inhibition.

Extracellular Vesicles for Disease Treatment

Traditional drug therapies suffer from problems such as easy drug degradation, side effects, and treatment resistance. Traditional disease diagnosis also suffers from high error rates and late diagnosis. Extracellular vesicles (EVs) are nanoscale spherical lipid bilayer vesicles secreted by cells that carry various biologically active components and are integral to intercellular communication. EVs can be found in different body fluids and may reflect the state of the parental cells, making them ideal noninvasive biomarkers for disease-specific diagnosis. The multifaceted characteristics of EVs render them optimal candidates for drug delivery vehicles, with evidence suggesting their efficacy in the treatment of various ailments. However, poor stability and easy degradation of natural EVs have affected their applications. To solve the problems of poor stability and easy degradation of natural EVs, they can be engineered and modified to obtain more stable and multifunctional EVs. In this study, we review the shortcomings of traditional drug delivery methods and describe how to modify EVs to form engineered EVs to improve their utilization. An innovative stimulus-responsive drug delivery system for EVs has also been proposed. We also summarize the current applications and research status of EVs in the diagnosis and treatment of different systemic diseases, and look forward to future research directions, providing research ideas for scholars.

Extracellular Histones as Exosome Membrane Proteins Regulated by Cell Stress

Histones are conserved nuclear proteins that function as part of the nucleosome in the regulation of chromatin structure and gene expression. Interestingly, extracellular histones populate biofluids from healthy individuals, and when elevated, may contribute to various acute and chronic diseases. It is generally assumed that most extracellular histones exist as nucleosomes, as components of extracellular chromatin. We analysed cell culture models under normal and stressed conditions to identify pathways of histone secretion. We report that core and linker histones localize to extracellular vesicles (EVs) and are secreted via the multivesicular body/exosome pathway. Upregulation of EV histone secretion occurs in response to cellular stress, with enhanced vesicle secretion and a shift towards a population of smaller EVs. Most histones were membrane associated with the outer surface of EVs. Degradation of EV-DNA did not impact significantly on EV-histone association. Individual histones  and histone octamers bound strongly to liposomes and EVs, but nucleosomes did not, showing histones do not require DNA for EV binding. Histones colocalized to tetraspanin positive EVs but using genetic or pharmacological intervention, we found that all known pathways of exosome biogenesis acted positively on histone secretion. Inhibition of autophagy and lysosomal degradation had a strong positive effect on EV histone release. Unexpectedly, EV-associated histones lacked the extensive post-translational modification of their nuclear counterparts, suggesting loss of PTMs may be involved in their trafficking or secretion. Our data does not support a significant role for EV-histones existing as nucleosomes. We show for the first time that histones are secreted from cells as membrane proteins via EVs/exosomes. This fundamental discovery provides support for further investigation of the biological activity of exosome associated histones and their role in disease.

Exosomes as carriers to stimulate an anti-cancer immune response in immunotherapy and as predictive markers

During this era of rapid advancements in cancer immunotherapy, the application of cell-released small vesicles that activate the immune system is of considerable interest. Exosomes are cell-derived nanovesicles that show great promise for the immunological treatment of cancer because of their immunogenicity and molecular transfer capacity. Recent technological advancements have enabled the identification of functional functions that exosome cargoes perform in controlling immune responses. Exosomes are originated specifically from immune cells and tumor cells and they show unique composition patterns directly related to the immunotherapy against cancer. Exosomes can also deliver their cargo to particular cells, which can affect the phenotypic and immune-regulatory functions of those cells. Exosomes can influence the course of cancer and have therapeutic benefits by taking part in several cellular processes; as a result, they have the dual properties of activating and restraining cancer. Exosomes have tremendous potential for cancer immunotherapy; they may develop into the most powerful cancer vaccines and carriers of targeted antigens and drugs. Comprehending the potential applications of exosomes in immune therapy is significant for regulating cancer progression. This review offers an analysis of the function of exosomes in immunotherapy, specifically as carriers that function as diagnostic indicators for immunological activation and trigger an anti-cancer immune response. Moreover, it summarizes the fundamental mechanism and possible therapeutic applications of exosome-based immunotherapy for human cancer.

Circulating Extracellular Vesicles as Promising Biomarkers for Precession Diagnostics: A Perspective on Lung Cancer

Extracellular vesicles (EVs) have emerged as promising biomarkers in liquid biopsy, owing to their ubiquitous presence in bodily fluids and their ability to carry disease-related cargo. Recognizing their significance in disease diagnosis and treatment, substantial efforts have been dedicated to developing efficient methods for EV isolation, detection, and analysis. EVs, heterogeneous membrane-encapsulated vesicles secreted by all cells, contain bioactive substances capable of modulating recipient cell biology upon internalization, including proteins, lipids, DNA, and various RNAs. Their prevalence across bodily fluids has positioned them as pivotal mediators in physiological and pathological processes, notably in cancer, where they hold potential as straightforward tumor biomarkers. This review offers a comprehensive examination of advanced nanotechnology-based techniques for detecting lung cancer through EV analysis. It begins by providing a brief overview of exosomes and their role in lung cancer progression. Furthermore, this review explores the evolving landscape of EV isolation and cargo analysis, highlighting the importance of characterizing specific biomolecular signatures within EVs for improved diagnostic accuracy in lung cancer patients. Innovative strategies for enhancing the sensitivity and specificity of EV isolation and detection, including the integration of microfluidic platforms and multiplexed biosensing technologies are summarized. The discussion then extends to key challenges associated with EV-based liquid biopsies, such as the standardization of isolation and detection protocols and the establishment of robust analytical platforms for clinical translation. This review highlights the transformative impact of EV-based liquid biopsy in lung cancer diagnosis, heralding a new era of personalized medicine and improved patient care.

Mechanisms of sterilizing immunity provided by an HIV-1 neutralizing antibody against mucosal infection

Broadly neutralizing antibodies (bnAbs) against HIV-1 have been shown to protect from systemic infection. When employing a novel challenge virus that uses HIV-1 Env for entry into target cells during the first replication cycle, but then switches to SIV Env usage, we demonstrated that bnAbs also prevented mucosal infection of the first cells. However, it remained unclear whether antibody Fc-effector functions contribute to this sterilizing immunity. Therefore, additional challenge viruses were produced that contain SIV Env and graded doses of a fusion-defective trimer of HIV-1 Env, to which the bnAb, PGT121 can bind without interfering with the SIV Env-based cell entry. After administration of either PGT121 or its mutant deficient in Fc-effector functions, rhesus macaques were intrarectally exposed to these challenge viruses and to those using either HIV-1 Env or SIV Env for entry into the first cells. Both antibodies similarly reduced infection events with the challenge virus using HIV-1 Env by a factor close to 200. Incorporating fusion-defective HIV-1 Env trimers into the particles of the challenge viruses at densities observed in primary virus isolates did not reduce SIV Env-mediated infection events. The results indicate that the sparsity of bnAb binding-sites on HIV-1 virions limits the contribution of Fc-effector functions to provide sterilizing immunity against mucosal viral infection. Hence, harnessing Fc-effector functions for sterilizing immunity against mucosal HIV-1 infection may require strategies to increase the degree of antibody opsonization.

Mechanisms of extracellular vesicle uptake and implications for the design of cancer therapeutics

The translation of pre-clinical anti-cancer therapies to regulatory approval has been promising, but slower than hoped. While innovative and effective treatments continue to achieve or seek approval, setbacks are often attributed to a lack of efficacy, failure to achieve clinical endpoints, and dose-limiting toxicities. Successful efforts have been characterized by the development of therapeutics designed to specifically deliver optimal and effective dosing to tumour cells while minimizing off-target toxicity. Much effort has been devoted to the rational design and application of synthetic nanoparticles to serve as targeted therapeutic delivery vehicles. Several challenges to the successful application of this modality as delivery vehicles include the induction of a protracted immune response that results in their rapid systemic clearance, manufacturing cost, lack of stability, and their biocompatibility. Extracellular vesicles (EVs) are a heterogeneous class of endogenous biologically produced lipid bilayer nanoparticles that mediate intercellular communication by carrying bioactive macromolecules capable of modifying cellular phenotypes to local and distant cells. By genetic, chemical, or metabolic methods, extracellular vesicles (EVs) can be engineered to display targeting moieties on their surface while transporting specific cargo to modulate pathological processes following uptake by target cell populations. This review will survey the types of EVs, their composition and cargoes, strategies employed to increase their targeting, uptake, and cargo release, and their potential as targeted anti-cancer therapeutic delivery vehicles.

Prospects and Current Challenges of Extracellular Vesicle-Based Biomarkers in Cancer

Cancer continues to impose a substantial global health burden, particularly among the elderly, where the ongoing global demographic shift towards an ageing population underscores the growing need for early cancer detection. This is essential for enabling personalised cancer care and optimised treatment throughout the disease course to effectively mitigate the increasing societal impact of cancer. Liquid biopsy has emerged as a promising strategy for cancer diagnosis and treatment monitoring, offering a minimally invasive method for the isolation and molecular profiling of circulating tumour-derived components. The expansion of the liquid biopsy approach to include the detection of tumour-derived extracellular vesicles (tdEVs) holds significant therapeutic opportunity. Evidence suggests that tdEVs carry cargo reflecting the contents of their cell-of-origin and are abundant within the blood, exhibiting superior stability compared to non-encapsulated tumour-derived material, such as circulating tumour nucleic acids and proteins. However, despite theoretical promise, several obstacles hinder the translation of extracellular vesicle-based cancer biomarkers into clinical practice. This critical review assesses the current prospects and challenges facing the adoption of tdEV biomarkers in clinical practice, offering insights into future directions and proposing strategies to overcome translational barriers. By addressing these issues, EV-based liquid biopsy approaches could revolutionise cancer diagnostics and management.

Eosinophil-derived extracellular vesicles: isolation and classification techniques and implications for disease pathophysiology

Eosinophils are leukocytes characterized by their ability to release granule content that is highly rich in enzymes and proteins. Besides the antihelminthic, bactericidal, and antiviral properties of eosinophils and their secretory granules, these also play a prominent role in the pathophysiology of diseases such as asthma, eosinophilic esophagitis, and other hypereosinophilic conditions by causing tissue damage and airway hyperresponsiveness. Although this cell was first recognized mainly for its capacity to release granule content, nowadays other capabilities such as cytokine secretion have been linked to its physiology, and research has found that eosinophils are not only involved in innate immunity, but also as orchestrators of immune responses. Nearly 10 yr ago, eosinophil-derived extracellular vesicles (EVs) were first described; since then, the EV field has grown exponentially, revealing their vital roles in intracellular communication. In this review, we synthesize current knowledge on eosinophil-derived EVs, beginning with a description of what they are and what makes them important regulators of disease, followed by an account of the methodologies used to isolate and characterize EVs. We also summarize current understanding of eosinophil-derived vesicles functionality, especially in asthma, the disease in which eosinophil-derived EVs have been most widely studied, describing how they modulate the role of eosinophils themselves (through autocrine signaling) and the way they affect airway structural cells and airway remodeling. Deeper understanding of this cell type could lead to novel research in eosinophil biology, its role in other diseases, and possible use of eosinophil-derived EVs as therapeutic targets.

Extracellular vesicles in cattle infected with bovine leukaemia virus: isolation and molecular analysis

Introduction

Exosomes are nanosized lipid bilayer membranous microvesicles, extracellularly released from a variety of mammalian cells. They mediate intercellular signalling by transporting several types of RNA, lipids and proteins and participate in the intercellular exchange of DNA, RNA, micro RNA, proteins and other components. These microvesicles are present in all body fluids in physiological and pathological conditions and reflect the state of the host organism. The aim of the study was the isolation and molecular determination of exosomes in blood and supernatant fluids of bovine dendritic cell cultures infected with bovine leukaemia virus (BLV).

Material and Methods

Exosomes were isolated by ultracentrifugation from the blood sera, plasma and supernatant of bovine BLV-infected and uninfected control dendritic cell cultures and their presence was confirmed with scanning electron and transmission electron microscopy. Western blot analysis of the structural BLV glycoprotein 51 (Env) and protein 24 (Gag) and of the tetraspanin exosomal markers CD9, CD63 and flotillin-1 was undertaken in BLV+ and control BLV- cattle.

Results

In exosomes of leukaemic cattle both BLV proteins and exosomal markers were detected. In healthy control animals only exosomal markers were determined.

Conclusion

Proteins of BLV were released with exosomes and could be transferred into recipient cells as an alternative propagation route not requiring virus infection.

Targeted drug delivery of engineered mesenchymal stem/stromal-cell-derived exosomes in cardiovascular disease: recent trends and future perspectives

In recent years, stem cells and their secretomes, notably exosomes, have received considerable attention in biomedical applications. Exosomes are cellular secretomes used for intercellular communication. They perform the function of intercellular messengers by facilitating the transport of proteins, lipids, nucleic acids, and therapeutic substances. Their biocompatibility, minimal immunogenicity, targetability, stability, and engineerable characteristics have additionally led to their application as drug delivery vehicles. The therapeutic efficacy of exosomes can be improved through surface modification employing functional molecules, including aptamers, antibodies, and peptides. Given their potential as targeted delivery vehicles to enhance the efficiency of treatment while minimizing adverse effects, exosomes exhibit considerable promise. Stem cells are considered advantageous sources of exosomes due to their distinctive characteristics, including regenerative and self-renewal capabilities, which make them well-suited for transplantation into injured tissues, hence promoting tissue regeneration. However, there are notable obstacles that need to be addressed, including immune rejection and ethical problems. Exosomes produced from stem cells have been thoroughly studied as a cell-free strategy that avoids many of the difficulties involved with cell-based therapy for tissue regeneration and cancer treatment. This review provides an in-depth summary and analysis of the existing knowledge regarding exosomes, including their engineering and cardiovascular disease (CVD) treatment applications.

A state-of-the-art review of the recent advances in exosome isolation and detection methods in viral infection

Proteins, RNA, DNA, lipids, and carbohydrates are only some of the molecular components found in exosomes released by tumor cells. They play an essential role in healthy and diseased cells as messengers of short- and long-distance intercellular communication. However, since exosomes are released by every kind of cell and may be found in blood and other bodily fluids, they may one day serve as biomarkers for a wide range of disorders. In many pathological conditions, including cancer, inflammation, and infection, they play a role. It has been shown that the biogenesis of exosomes is analogous to that of viruses and that the exosomal cargo plays an essential role in the propagation, dissemination, and infection of several viruses. Bidirectional modulation of the immune response is achieved by the ability of exosomes associated with viruses to facilitate immunological escape and stimulate the body's antiviral immune response. Recently, exosomes have received a lot of interest due to their potential therapeutic use as biomarkers for viral infections such as human immunodeficiency virus (HIV), Hepatitis B virus (HBV), Hepatitis C virus (HCV), Epstein-Barr virus (EBV), and SARS-CoV-2. This article discusses the purification procedures and detection techniques for exosomes and examines the research on exosomes as a biomarker of viral infection.

Exosome subpopulations: The isolation and the functions in diseases

Exosomes are nanoscale extracellular vesicles secreted by cells. Exosomes mediate intercellular communication by releasing their bioactive contents (e.g., DNAs, RNAs, lipids, proteins, and metabolites). The components of exosomes are regulated by the producing cells of exosomes. Due to their diverse origins, exosomes are highly heterogeneous in size, content, and function. Depending on these characteristics, exosomes can be divided into multiple subpopulations which have different functions. Efficient enrichment of specific subpopulations of exosomes helps to investigate their biological functions. Accordingly, numerous techniques have been developed to isolate specific subpopulations of exosomes. This review systematically introduces emerging new technologies for the isolation of different exosome subpopulations and summarizes the critical role of specific exosome subpopulations in diseases, especially in tumor occurrence and progression.

Extracellular vesicles and co-isolated endogenous retroviruses from murine cancer cells differentially affect dendritic cells

Cells secrete extracellular vesicles (EVs) and non-vesicular extracellular (nano)particles (NVEPs or ENPs) that may play a role in intercellular communication. Tumor-derived EVs have been proposed to induce immune priming of antigen presenting cells or to be immuno-suppressive agents. We suspect that such disparate functions are due to variable compositions in EV subtypes and ENPs. We aimed to characterize the array of secreted EVs and ENPs of murine tumor cell lines. Unexpectedly, we identified virus-like particles (VLPs) from endogenous murine leukemia virus in preparations of EVs produced by many tumor cells. We established a protocol to separate small EVs from VLPs and ENPs. We compared their protein composition and analyzed their functional interaction with target dendritic cells. ENPs were poorly captured and did not affect dendritic cells. Small EVs specifically induced dendritic cell death. A mixed large/dense EV/VLP preparation was most efficient to induce dendritic cell maturation and antigen presentation. Our results call for systematic re-evaluation of the respective proportions and functions of non-viral EVs and VLPs produced by murine tumors and their contribution to tumor progression.

Exploring the Versatility of Exosomes: A Review on Isolation, Characterization, Detection Methods, and Diverse Applications

Extracellular vesicles (EVs) are crucial mediators of intercellular communication and can be classified based on their physical properties, biomolecular structure, and origin. Among EVs, exosomes have garnered significant attention due to their potential as therapeutic and diagnostic tools. Exosomes are released via fusion of multivesicular bodies on plasma membranes and can be isolated from various biofluids using methods such as differential ultracentrifugation, immune affinity capture, ultrafiltration, and size exclusion chromatography. Herein, an overview of different techniques for exosome characterization and isolation, as well as the diverse applications of exosome detection, including their potential use in drug delivery and disease diagnosis, is provided. Additionally, we discuss the emerging field of exosome detection by sensors, which offers an up-and-coming avenue for point-of-care diagnostic tools development. Overall, this review aims to provide a exhaustive and up-to-date summary of the current state of exosome research.

Exosomes multifunctional roles in HIV-1: insight into the immune regulation, vaccine development and current progress in delivery system

Human Immunodeficiency Virus (HIV-1) is known to establish a persistent latent infection. The use of combination antiretroviral therapy (cART) can effectively reduce the viral load, but the treatment can be costly and may lead to the development of drug resistance and life-shortening side effects. It is important to develop an ideal and safer in vivo target therapy that will effectively block viral replication and expression in the body. Exosomes have recently emerged as a promising drug delivery vehicle due to their low immunogenicity, nanoscale size (30-150nm), high biocompatibility, and stability in the targeted area. Exosomes, which are genetically produced by different types of cells such as dendritic cells, neurons, T and B cells, epithelial cells, tumor cells, and mast cells, are designed for efficient delivery to targeted cells. In this article, we review and highlight recent developments in the strategy and application of exosome-based HIV-1 vaccines. We also discuss the use of exosome-based antigen delivery systems in vaccine development. HIV-1 antigen can be loaded into exosomes, and this modified cargo can be delivered to target cells or tissues through different loading approaches. This review also discusses the immunological prospects of exosomes and their role as biomarkers in disease progression. However, there are significant administrative and technological obstacles that need to be overcome to fully harness the potential of exosome drug delivery systems.

Extracellular vesicles as next generation immunotherapeutics

Extracellular vesicles (EVs) function as a mode of intercellular communication and molecular transfer to elicit diverse biological/functional response. Accumulating evidence has highlighted that EVs from immune, tumour, stromal cells and even bacteria and parasites mediate the communication of various immune cell types to dynamically regulate host immune response. EVs have an innate capacity to evade recognition, transport and transfer functional components to target cells, with subsequent removal by the immune system, where the immunological activities of EVs impact immunoregulation including modulation of antigen presentation and cross-dressing, immune activation, immune suppression, and immune surveillance, impacting the tumour immune microenvironment. In this review, we outline the recent progress of EVs in immunorecognition and therapeutic intervention in cancer, including vaccine and targeted drug delivery and summarise their utility towards clinical translation. We highlight the strategies where EVs (natural and engineered) are being employed as a therapeutic approach for immunogenicity, tumoricidal function, and vaccine development, termed immuno-EVs. With seminal studies providing significant progress in the sequential development of engineered EVs as therapeutic anti-tumour platforms, we now require direct assessment to tune and improve the efficacy of resulting immune responses - essential in their translation into the clinic. We believe such a review could strengthen our understanding of the progress in EV immunobiology and facilitate advances in engineering EVs for the development of novel EV-based immunotherapeutics as a platform for cancer treatment.

Prophage Induction Causes Geobacter Electroactive Biofilm Decay

Sustaining a metabolically active electroactive biofilm (EAB) is essential for the high efficiency and durable operation of microbial fuel cells (MFCs). However, EABs usually decay during long-term operation, and, until now, the causes remain unknown. Here, we report that lysogenic phages can cause EAB decay in Geobacter sulfurreducens fuel cells. A cross-streak agar assay and bioinformatic analysis revealed the presence of prophages on the G. sulfurreducens genome, and a mitomycin C induction assay revealed the lysogenic to lytic transition of those prophages, resulting in a progressive decay in both current generation and the EAB. Furthermore, the addition of phages purified from decayed EAB resulted in accelerated decay of the EAB, thereafter contributing to a faster decline in current generation; otherwise, deleting prophage-related genes rescued the decay process. Our study provides the first evidence of an interaction between phages and electroactive bacteria and suggests that attack by phages is a primary cause of EAB decay, having significant implications in bioelectrochemical systems.

Extracellular vesicle distribution and localization in skeletal muscle at rest and following disuse atrophy

BACKGROUND

Skeletal muscle (SkM) is a large, secretory organ that produces and releases myokines that can have autocrine, paracrine, and endocrine effects. Whether extracellular vesicles (EVs) also play a role in the SkM adaptive response and ability to communicate with other tissues is not well understood. The purpose of this study was to investigate EV biogenesis factors, marker expression, and localization across cell types in the skeletal muscle. We also aimed to investigate whether EV concentrations are altered by disuse atrophy.

METHODS

To identify the potential markers of SkM-derived EVs, EVs were isolated from rat serum using density gradient ultracentrifugation, followed by fluorescence correlation spectroscopy measurements or qPCR. Single-cell RNA sequencing (scRNA-seq) data from rat SkM were analyzed to assess the EV biogenesis factor expression, and cellular localization of tetraspanins was investigated by immunohistochemistry. Finally, to assess the effects of mechanical unloading on EV expression in vivo, EV concentrations were measured in the serum by nanoparticle tracking analysis in both a rat and human model of disuse.

RESULTS

In this study, we show that the widely used markers of SkM-derived EVs, α-sarcoglycan and miR-1, are undetectable in serum EVs. We also found that EV biogenesis factors, including the tetraspanins CD63, CD9, and CD81, are expressed by a variety of cell types in SkM. SkM sections showed very low detection of CD63, CD9, and CD81 in myofibers and instead accumulation within the interstitial space. Furthermore, although there were no differences in serum EV concentrations following hindlimb suspension in rats, serum EV concentrations were elevated in human subjects after bed rest.

CONCLUSIONS

Our findings provide insight into the distribution and localization of EVs in SkM and demonstrate the importance of methodological guidelines in SkM EV research.

A compendium of single extracellular vesicle flow cytometry

Flow cytometry (FCM) offers a multiparametric technology capable of characterizing single extracellular vesicles (EVs). However, most flow cytometers are designed to detect cells, which are larger than EVs. Whereas cells exceed the background noise, signals originating from EVs partly overlap with the background noise, thereby making EVs more difficult to detect than cells. This technical mismatch together with complexity of EV-containing fluids causes limitations and challenges with conducting, interpreting and reproducing EV FCM experiments. To address and overcome these challenges, researchers from the International Society for Extracellular Vesicles (ISEV), International Society for Advancement of Cytometry (ISAC), and the International Society on Thrombosis and Haemostasis (ISTH) joined forces and initiated the EV FCM working group. To improve the interpretation, reporting, and reproducibility of future EV FCM data, the EV FCM working group published an ISEV position manuscript outlining a framework of minimum information that should be reported about an FCM experiment on single EVs (MIFlowCyt-EV). However, the framework contains limited background information. Therefore, the goal of this compendium is to provide the background information necessary to design and conduct reproducible EV FCM experiments. This compendium contains background information on EVs, the interaction between light and EVs, FCM hardware, experimental design and preanalytical procedures, sample preparation, assay controls, instrument data acquisition and calibration, EV characterization, and data reporting. Although this compendium focuses on EVs, many concepts and explanations could also be applied to FCM detection of other particles within the EV size range, such as bacteria, lipoprotein particles, milk fat globules, and viruses.

Prospective Advances of Extracellular Vesicles Investigation in Cardiovascular and Metabolic Research

Extracellular vesicles (EVs) play an important role in cardiovascular and metabolic diseases through intercellular communication. Although there has been extensive research on EVs, there are still some unsolved problems in the technologies of investigation of EVs. In this chapter, we reviewed the current knowledge of EVs functions in cardiovascular and metabolic pathophysiology and EVs as biomarkers and therapeutic agents in cardiovascular and metabolic diseases. We also addressed the challenges in isolation and identification of EVs as well as challenges in visualization and tracking of EVs. By addressing these challenges, we hope to have a more in-depth understanding of the biological functions of EVs.

Exosomes Released by Influenza-Virus-Infected Cells Carry Factors Capable of Suppressing Immune Defense Genes in Naïve Cells

Background: Exosomes are involved in intercellular communication and can transfer regulatory molecules between cells. Consequently, they can participate in host immune response regulation. For the influenza A virus (IAV), there is very limited information on changes in exosome composition during cell infection shedding light on the potential role of these extracellular membrane vesicles. Thus, the aim of our work was to study changes in exosomal composition following IAV infection of cells, as well as to evaluate their effect on uninfected cells. Methods: To characterize changes in the composition of cellular miRNAs and mRNAs of exosomes during IAV infection of A549 cells, NGS was used, as well as PCR to identify viral genes. Naïve A549 cells were stimulated with infected-cell-secreted exosomes for studying their activity. Changes in the expression of genes associated with the cell's immune response were shown using PCR. The effect of exosomes on IAV replication was shown in MDCK cells using In-Cell ELISA and PCR of the supernatants. Results: A change in the miRNA composition (miR-21-3p, miR-26a-5p, miR-23a-5p, miR-548c-5p) and mRNA composition (RPL13A, MKNK2, TRIB3) of exosomes under the influence of the IAV was shown. Many RNAs were involved in the regulation of the immune response of the cell, mainly by suppressing it. After exosome stimulation of naïve cells, a significant decrease in the expression of genes involved in the immune response was shown (RIG1, IFIT1, MDA5, COX2, NFκB, AnxA1, PKR, IL6, IL18). When infecting MDCK cells, a significant decrease in nucleoprotein levels was observed in the presence of exosomes secreted by mock-infected cells. Viral levels in supernatants also decreased. Conclusions: Exosomes secreted by IAV-infected cells could reduce the immune response of neighboring intact cells, leading to more effective IAV replication. This may be associated both with regulatory functions of cellular miRNAs and mRNAs carried by exosomes, or with the presence of viral mRNAs encoding proteins with an immunosuppressive function.

The role of milk-derived exosomes in the treatment of diseases

Exosomes (EXOs) are natural nanoparticles of endosome origin that are secreted by a variety of cells in the body. Exosomes have been found in bio-fluids such as urine, saliva, amniotic fluid, and ascites, among others. Milk is the only commercially available biological liquid containing EXOs. Proof that exosomes are essential for cell-to-cell communication is increasingly being reported. Studies have shown that they migrate from the cell of origin to various bioactive substances, including membrane receptors, proteins, mRNAs, microRNAs, and organelles, or they can stimulate target cells directly through interactions with receptors. Because of the presence of specific proteins, lipids, and RNAs, exosomes act in physiological and pathological conditions in vivo. Other salient features of EXOs include their long half-life in the body, no tumorigenesis, low immune response, good biocompatibility, ability to target cells through their surface biomarkers, and capacity to carry macromolecules. EXOs have been introduced to the scientific community as important, efficient, and attractive nanoparticles. They can be extracted from different sources and have the same characteristics as their parents. EXOs present in milk can be separated by size exclusion chromatography, density gradient centrifugation, or (ultra) centrifugation; however, the complex composition of milk that includes casein micelles and milk fat globules makes it necessary to take additional issues into consideration when employing the mentioned techniques with milk. As a rich source of EXOs, milk has unique properties that, in addition to its role as a carrier, promotes its use in treating diseases such as digestive problems, skin ulcers, and cancer, Moreover, EXOs derived from camel milk are reported to reduce the risk of oxidative stress and cancer. Milk-derived exosomes (MDEs) from yak milk improves gastrointestinal tract (GIT) development under hypoxic conditions. Furthermore, yak-MDEs have been suggested to be the best treatment for intestinal epithelial cells (IEC-6 cell line). Because of their availability as well as the non-invasiveness and cost-effectiveness of their preparation, isolates from mammals milk can be excellent resources for studies related to EXOs. These features also make it possible to exploit MDEs in clinical trials. The current study aimed to investigate the therapeutic applications of EXOs isolated from various milk sources.

Presence of Intact Hepatitis B Virions in Exosomes

BACKGROUND & AIMS

Hepatitis B virus (HBV) was identified as an enveloped DNA virus with a diameter of 42 nm. Multivesicular bodies play a central role in HBV egress and exosome biogenesis. In light of this, it was studied whether intact virions wrapped in exosomes are released by HBV-producing cells.

METHODS

Robust methods for efficient separation of exosomes from virions were established. Exosomes were subjected to limited detergent treatment for release of viral particles. Electron microscopy of immunogold labeled ultrathin sections of purified exosomes was performed for characterization of exosomal HBV. Exosome formation/release was affected by inhibitors or Crispr/Cas-mediated gene silencing. Infectivity/uptake of exosomal HBV was investigated in susceptible and non-susceptible cells.

RESULTS

Exosomes could be isolated from supernatants of HBV-producing cells, which are characterized by the presence of exosomal and HBV markers. These exosomal fractions could be separated from the fractions containing free virions. Limited detergent treatment of exosomes causes stepwise release of intact HBV virions and naked capsids. Inhibition of exosome morphogenesis impairs the release of exosome-wrapped HBV. Electron microscopy confirmed the presence of intact virions in exosomes. Moreover, the presence of large hepatitis B virus surface antigen on the surface of exosomes derived from HBV expressing cells was observed, which conferred exosome-encapsulated HBV initiating infection in susceptible cells in a , large hepatitis B virus surface antigen/Na⁺-taurocholate co-transporting polypeptide-dependent manner. The uptake of exosomal HBV with low efficiency was also observed in non-permissive cells.

CONCLUSION

These data indicate that a fraction of intact HBV virions can be released as exosomes. This reveals a so far not described release pathway for HBV.

Extracellular Vesicles (EVs) Are Copurified with Feline Calicivirus, yet EV-Enriched Fractions Remain Infectious

Feline calicivirus (FCV) is a major cause of upper respiratory disease in cats and is often used as a model for human norovirus, making it of great veterinary and human medical importance. However, questions remain regarding the route of entry of FCV in vivo. Increasing work has shown that extracellular vesicles (EVs) can be active in viral infectivity, yet there is no work examining the role of EVs in FCV infection. Here, we begin to address this knowledge gap by characterizing EVs produced by a feline mammary epithelial cell line (FMEC). We have confirmed that EVs are produced by infected and mock-infected FMECs and that both virions and EVs are coisolated with standard methods of virus purification. We also show that they can be enriched differentially by continuous iodixanol density gradient. EVs were enriched at a density of 1.10 g/mL confirmed by tetraspanin expression, size profile, and transmission electron microscopy (TEM). Maximum enrichment of FCV at a density of 1.18 g/mL was confirmed by titration, quantitative reverse transcriptase PCR (q-RT PCR), and TEM. However, infectious virus was recovered from nearly all samples. When used to infect in vitro epithelium, both EV-rich and virus-rich fractions had the same levels of infectiousness as determined by percentage of wells infected or titer achieved postinfection. These findings highlight the importance of coisolates during viral purification, showing that EVs may represent a parallel route of entry that has previously been overlooked. Additional experiments are necessary to explore the role of EVs in FCV infection. IMPORTANCE Feline calicivirus (FCV) is a common cause of upper respiratory infection in cats. Both healthy and infected cells produce small particles called extracellular vesicles (EVs), which are nanoparticles that act as messengers between cells and can be hijacked during viral infection. Historically, the role of EVs in viral infection has been overlooked, and subsequently no group has studied the role of EVs in FCV infection. We hypothesized that EVs may play a role in FCV infection. Here, we show that EVs are copurified with FCV when collecting virus. To study their individual effects, we successfully enrich for viral particles and EVs separately by taking advantage of their different densities. Our initial studies show that EV-enriched versus virus-enriched fractions are equally able to infect cells in culture. These findings highlight the need to both consider the purity of virus after purification and to further study EVs' role in natural FCV infection.

Plasma CD16+ Extracellular Vesicles Associate with Carotid Artery Intima-Media Thickness in HIV+ Adults on Combination Antiretroviral Therapy

HIV-infected individuals have increased risk for cardiovascular disease (CVD) despite suppressive antiretroviral therapy (ART). This is likely a result of persistent immune activation and systemic inflammation. Extracellular vesicles (EVs) have emerged as critical mediators of intercellular communication and may drive inflammation contributing to CVD. EVs were characterized in plasma from 74 HIV-infected individuals on combination antiretroviral therapy (cART) and 64 HIV-uninfected controls with paired carotid intima-media thickness (cIMT) assessment. EVs were profiled with markers reflecting lymphoid, myeloid, and endothelial origin. Seventeen plasma inflammatory biomarkers were also assessed. Human umbilical vein endothelial cell (HUVEC) apoptosis was quantified after EV exposure. A significant correlation was observed in HIV-infected participants between cIMT and EVs expressing CD16, and the monocyte-related markers CD4, CD14, and CX3CR1 showed a similar but nonsignificant association with cIMT. No significant correlation between cIMT measurements from HIV-uninfected individuals and EVs was observed. Levels of serum amyloid A, C-reactive protein, and myeloperoxidase significantly correlated with CD14⁺, CD16⁺, and CX3CR1⁺ EVs. No correlation was noted between cIMT and soluble inflammatory markers. HUVECs showed increased necrosis after exposure to the EV-containing fraction of plasma derived from HIV-infected individuals compared to uninfected controls. Our study reveals that EVs expressing monocyte markers correlated with cIMT in HIV-infected individuals on cART. Moreover, EV fractions derived from HIV-infected individuals lead to greater endothelial cell death via necrotic pathways. Collectively, EVs have potential as biomarkers of and therapeutic targets in the pathogenesis of CVD in the setting of treated HIV disease. IMPORTANCE HIV-infected individuals have a 2-fold-increased risk of cardiovascular disease compared with the general population, yet the mechanisms underlying this comorbidity are unclear. Extracellular vesicles have emerged as important mediators in cell-cell communication and, given what we know of their biology, may drive inflammation contributing to cardiovascular disease in this vulnerable population.

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.

Principles and Problems of Exosome Isolation from Biological Fluids

Exosomes, the subclass of small membrane extracellular vesicles, have great diagnostic and therapeutic potential, but the lack of standardized methods for their efficient isolation and analysis limits the introduction of exosomal technologies into clinical practice. This review discusses the problems associated with the isolation of exosomes from biological fluids, as well as the principles of traditional and alternative methods of isolation. The aim of the presented review is to illustrate the variety of approaches based on the physical and biochemical properties of exosomes that can be used for exosome isolation. The advantages and disadvantages of different methods are discussed.

Plasma-Enabled Smart Nanoexosome Platform as Emerging Immunopathogenesis for Clinical Viral Infection

Smart nanoexosomes are nanosized structures enclosed in lipid bilayers that are structurally similar to the viruses released by a variety of cells, including the cells lining the respiratory system. Of particular importance, the interaction between smart nanoexosomes and viruses can be used to develop antiviral drugs and vaccines. It is possible that nanoexosomes will be utilized and antibodies will be acquired more successfully for the transmission of an immune response if reconvalescent plasma (CP) is used instead of reconvalescent plasma exosomes (CPExo) in this concept. Convalescent plasma contains billions of smart nanoexosomes capable of transporting a variety of molecules, including proteins, lipids, RNA and DNA among other viral infections. Smart nanoexosomes are released from virus-infected cells and play an important role in mediating communication between infected and uninfected cells. Infections use the formation, production and release of smart nanoexosomes to enhance the infection, transmission and intercellular diffusion of viruses. Cell-free smart nanoexosomes produced by mesenchymal stem cells (MSCs) could also be used as cell-free therapies in certain cases. Smart nanoexosomes produced by mesenchymal stem cells can also promote mitochondrial function and heal lung injury. They can reduce cytokine storms and restore the suppression of host antiviral defenses weakened by viral infections. This study examines the benefits of smart nanoexosomes and their roles in viral transmission, infection, treatment, drug delivery and clinical applications. We also explore some potential future applications for smart nanoexosomes in the treatment of viral infections.

Conventional and Nonconventional Sources of Exosomes-Isolation Methods and Influence on Their Downstream Biomedical Application

Despite extensive study of extracellular vesicles (EVs), specifically exosomes (EXs) as biomarkers, important modulators of physiological or pathological processes, or therapeutic agents, relatively little is known about nonconventional sources of EXs, such as invertebrate or plant EXs, and their uses. Likewise, there is no clear information on the overview of storage conditions and currently used isolation methods, including new ones, such as microfluidics, which fundamentally affect the characterization of EXs and their other biomedical applications. The purpose of this review is to briefly summarize conventional and nonconventional sources of EXs, storage conditions and typical isolation methods, widely used kits and new "smart" technologies with emphasis on the influence of isolation techniques on EX content, protein detection, RNA, mRNA and others. At the same time, attention is paid to a brief overview of the direction of biomedical application of EXs, especially in diagnostics, therapy, senescence and aging and, with regard to the current situation, in issues related to Covid-19.

Exosomes as Carriers for Drug Delivery in Cancer Therapy

Exosomes are extracellular vesicles secreted by cells with a particle size of 30-150 nm in diameter. Exosomes can be used as natural drug carriers. The treatment of cancer with drug-loaded exosomes is an area of high interest. This review introduces the composition, function, isolation and characterization of exosomes, and briefly describes the selection of exosome donor cells and methods for drug loading. Through studies on therapies with drug-loaded exosomes in gastric cancer, lung cancer, brain cancer and other cancers, the advantages and disadvantages of drug-loaded exosomes have been analyzed.

Exosomes and Other Extracellular Vesicles with High Therapeutic Potential: Their Applications in Oncology, Neurology, and Dermatology

Until thirty years ago, it was believed that extracellular vesicles (EVs) were used to remove unnecessary compounds from the cell. Today, we know about their enormous potential in diagnosing and treating various diseases. EVs are essential mediators of intercellular communication, enabling the functional transfer of bioactive molecules from one cell to another. Compared to laboratory-created drug nanocarriers, they are stable in physiological conditions. Furthermore, they are less immunogenic and cytotoxic compared to polymerized vectors. Finally, EVs can transfer cargo to particular cells due to their membrane proteins and lipids, which can implement them to specific receptors in the target cells. Recently, new strategies to produce ad hoc exosomes have been devised. Cells delivering exosomes have been genetically engineered to overexpress particular macromolecules, or transformed to release exosomes with appropriate targeting molecules. In this way, we can say tailor-made therapeutic EVs are created. Nevertheless, there are significant difficulties to solve during the application of EVs as drug-delivery agents in the clinic. This review explores the diversity of EVs and the potential therapeutic options for exosomes as natural drug-delivery vehicles in oncology, neurology, and dermatology. It also reflects future challenges in clinical translation.

Reassessment of the Proteomic Composition and Function of Extracellular Vesicles in the Seminal Plasma

Seminal plasma contains a high concentration of extracellular vesicles (EVs). The heterogeneity of small EVs or the presence of nonvesicular extracellular matter (NV) pose major obstacles in understanding the composition and function of seminal EVs. In this study, we employed high-resolution density gradient fractionation to accurately characterize the composition and function of seminal EVs and NV. We found that the seminal EVs could be divided into 3 different subtypes-namely, high-density EV (EV-H), medium-density EV (EV-M), and low-density EV (EV-L)-after purification using iodixanol, while NV was successfully isolated. EVs and NV display different features in size, shape, and expression of some classic exosome markers. Both EV-H and NV could markedly promote sperm motility and capacitation compared with EV-M and EV-L, whereas only the NV fraction induced sperm acrosome reaction. Proteomic analysis results showed that EV-H, EV-M, EV-L, and NV had different protein components and were involved in different physiological functions. Further study showed that EV-M might reduce the production of sperm intrinsic reactive oxygen species through glutathione S-transferase mu 2. This study provides novel insights into important aspects of seminal EVs constituents and sounder footing to explore their functional properties in male fertility.

A Comprehensive Insight into the Role of Exosomes in Viral Infection: Dual Faces Bearing Different Functions

Extracellular vesicles (EVs) subtype, exosome is an extracellular nano-vesicle that sheds from cells' surface and originates as intraluminal vesicles during endocytosis. Firstly, it was thought to be a way for the cell to get rid of unwanted materials as it loaded selectively with a variety of cellular molecules, including RNAs, proteins, and lipids. However, it has been found to play a crucial role in several biological processes such as immune modulation, cellular communication, and their role as vehicles to transport biologically active molecules. The latest discoveries have revealed that many viruses export their viral elements within cellular factors using exosomes. Hijacking the exosomal pathway by viruses influences downstream processes such as viral propagation and cellular immunity and modulates the cellular microenvironment. In this manuscript, we reviewed exosomes biogenesis and their role in the immune response to viral infection. In addition, we provided a summary of how some pathogenic viruses hijacked this normal physiological process. Viral components are harbored in exosomes and the role of these exosomes in viral infection is discussed. Understanding the nature of exosomes and their role in viral infections is fundamental for future development for them to be used as a vaccine or as a non-classical therapeutic strategy to control several viral infections.

The Yin and Yang of exosome isolation methods: conventional practice, microfluidics, and commercial kits

Exosomes are a subset of extracellular vesicles released from various cells, and they can be found in different bodily fluids. Exosomes are used as biomarkers to diagnose many diseases and to monitor therapy efficiency as they represent the status and origin of the cell, which they are released from. Considering that they co-exist in bodily fluids with other types of particles, their isolation still remains challenging since conventional separation methods are time-consuming, user-dependent, and result in low isolation yield. This review summarizes the conventional strategies and microfluidic-based methods for exosome isolation along with their strengths and limitations. Microfluidic devices emerge as a promising approach to overcome the limitations of the conventional methods due to their inherent characteristics, such as the need for minute sample volume and rapid operation, in order to isolate exosomes with a high yield and a high purity in a short amount of time, which make them unprecedented tools for molecular biology and clinical applications. This review elaborates on the existing microfluidic-based exosome isolation methods and denotes their benefits and drawbacks. Herein, we also introduce various commercially available platforms and kits for exosome isolation along with their working principles.

Optimizing extracellular vesicles' isolation from chronic lymphocytic leukemia patient plasma and cell line supernatant

In chronic lymphocytic leukemia (CLL) and very likely all cancer types, extracellular vesicles (EVs) are a common mechanism by which intercellular messages are communicated between normal, diseased, and transformed cells. Studies of EVs in CLL and other cancers have great variability and often lack reproducibility. For CLL patient plasma and cell lines, we sought to characterize current approaches used in isolating EV products and understand whether cell culture-conditioned media or complex biological fluids confound results. Utilizing nanoparticle tracking analysis, protein quantification, and electron microscopy, we show that ultracentrifugation with an OptiPrep cushion can effectively minimize contaminants from starting materials including plasma and conditioned media of CLL cell lines grown in EV-depleted complete RPMI media but not grown in the serum-free media AIM V commonly used in CLL experimental work. Moreover, we confirm the benefit of including 25 mM trehalose in PBS during EV isolation steps to reduce EV aggregation, to preserve function for downstream applications and characterization. Furthermore, we report the highest particles/μg EVs were obtained from our CLL cell lines utilizing the CELLine bioreactor flask. Finally, we optimized a proliferation assay that offers a functional evaluation of our EVs with minimal sample requirements.

Critical Assessment of Purification and Analytical Technologies for Enveloped Viral Vector and Vaccine Processing and Their Current Limitations in Resolving Co-Expressed Extracellular Vesicles

Viral vectors and viral vaccines are invaluable tools in prevention and treatment of diseases. Many infectious diseases are controlled using vaccines designed from subunits or whole viral structures, whereas other genetic diseases and cancers are being treated by viruses used as vehicles for delivering genetic material in gene therapy or as therapeutic agents in virotherapy protocols. Viral vectors and vaccines are produced in different platforms, from traditional embryonated chicken eggs to more advanced cell cultures. All these expression systems, like most cells and cellular tissues, are known to spontaneously release extracellular vesicles (EVs). EVs share similar sizes, biophysical characteristics and even biogenesis pathways with enveloped viruses, which are currently used as key ingredients in a number of viral vectors and licensed vaccine products. Herein, we review distinctive features and similarities between EVs and enveloped viruses as we revisit the downstream processing steps and analytical technologies currently implemented to produce and document viral vector and vaccine products. Within a context of well-established viral vector and vaccine safety profiles, this review provides insights on the likely presence of EVs in the final formulation of enveloped virus products and discusses the potential to further resolve and document these components.

The Role of Extracellular Vesicles in Disease Progression and Detection of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the most common primary liver malignancy and one of the leading causes of cancer-related death worldwide. Despite the improvements in surveillance and treatment, the prognosis of HCC remains poor. Extracellular vesicles (EVs) are a heterogeneous group of phospholipid bilayer-enclosed particles circulating in the bloodstream and mediating intercellular communication. Emerging studies have shown that EVs play a crucial role in regulating the proliferation, immune escape, and metastasis of HCC. In addition, because EVs are present in the circulation at relatively early stages of disease, they are getting attention as an attractive biomarker for HCC detection. Over the past decade, dedicated efforts have been made to isolate EVs more efficiently and make them useful tools in different clinical settings. In this review article, we provide an overview of the EVs isolation methods and highlight the role of EVs as mediators in the pathogenesis and progression of HCC. Lastly, we summarize the potential applications of EVs in early-stage HCC detection.

Urinary Extracellular Vesicles: Uncovering the Basis of the Pathological Processes in Kidney-Related Diseases

Intercellular communication governs multicellular interactions in complex organisms. A variety of mechanisms exist through which cells can communicate, e.g., cell-cell contact, the release of paracrine/autocrine soluble molecules, or the transfer of extracellular vesicles (EVs). EVs are membrane-surrounded structures released by almost all cell types, acting both nearby and distant from their tissue/organ of origin. In the kidney, EVs are potent intercellular messengers released by all urinary system cells and are involved in cell crosstalk, contributing to physiology and pathogenesis. Moreover, urine is a reservoir of EVs coming from the circulation after crossing the glomerular filtration barrier—or originating in the kidney. Thus, urine represents an alternative source for biomarkers in kidney-related diseases, potentially replacing standard diagnostic techniques, including kidney biopsy. This review will present an overview of EV biogenesis and classification and the leading procedures for isolating EVs from body fluids. Furthermore, their role in intra-nephron communication and their use as a diagnostic tool for precision medicine in kidney-related disorders will be discussed.

Latent HIV-Exosomes Induce Mitochondrial Hyperfusion Due to Loss of Phosphorylated Dynamin-Related Protein 1 in Brain Endothelium

Damage to the cerebral vascular endothelium is a critical initiating event in the development of HIV-1-associated neurocognitive disorders. To study the role of mitochondria in cerebral endothelial dysfunction, we investigated how exosomes, isolated from both cell lines with integrated provirus and HIV-1 infected primary cells (HIV-exosomes), accelerate the dysfunction of primary human brain microvascular endothelial cells (HBMVECs) by inducing mitochondrial hyperfusion, and reducing the expression of phosphorylated endothelial nitric oxide synthase (p-eNOS). The quantitative analysis of the extracellular vesicles (EVs) indicates that the isolated EVs were predominantly exosomes. It was further supported by the detection of exosomal markers, and the absence of large EV-related protein in the isolated EVs. The exosomes were readily taken up by primary HBMVECs. HIV-exosomes induce cellular and mitochondrial superoxide production but reduce mitochondrial membrane potential in HBMVECs. HIV-exosomes increase mitochondrial hyperfusion, possibly due to loss of phosphorylated dynamin-related protein 1 (p-DRP1). HIV-exosomes, containing the HIV-Tat protein, and viral Tat protein reduce the expression of p-DRP1 and p-eNOS, and accelerate brain endothelial dysfunction. Finally, exosomes isolated from HIV-1 infected primary human peripheral blood mononuclear cells (hPBMCs) produce more exosomes than uninfected controls and reduce both p-DRP1 and p-eNOS expressions in primary HBMVECs. Our novel findings reveal the significant role of HIV-exosomes on dysregulation of mitochondrial function, which induces adverse changes in the function of the brain microvascular endothelium.

A Role for Extracellular Vesicles in SARS-CoV-2 Therapeutics and Prevention

Extracellular vesicles (EVs) are the common designation for ectosomes, microparticles and microvesicles serving dominant roles in intercellular communication. Both viable and dying cells release EVs to the extracellular environment for transfer of cell, immune and infectious materials. Defined morphologically as lipid bi-layered structures EVs show molecular, biochemical, distribution, and entry mechanisms similar to viruses within cells and tissues. In recent years their functional capacities have been harnessed to deliver biomolecules and drugs and immunological agents to specific cells and organs of interest or disease. Interest in EVs as putative vaccines or drug delivery vehicles are substantial. The vesicles have properties of receptors nanoassembly on their surface. EVs can interact with specific immunocytes that include antigen presenting cells (dendritic cells and other mononuclear phagocytes) to elicit immune responses or affect tissue and cellular homeostasis or disease. Due to potential advantages like biocompatibility, biodegradation and efficient immune activation, EVs have gained attraction for the development of treatment or a vaccine system against the severe acute respiratory syndrome coronavirus 2 (SARS CoV-2) infection. In this review efforts to use EVs to contain SARS CoV-2 and affect the current viral pandemic are discussed. An emphasis is made on mesenchymal stem cell derived EVs' as a vaccine candidate delivery system.

The Role of Viral Proteins in the Regulation of Exosomes Biogenesis

Exosomes are membrane-bound vesicles of endocytic origin, secreted into the extracellular milieu, in which various biological components such as proteins, nucleic acids, and lipids reside. A variety of external stimuli can regulate the formation and secretion of exosomes, including viruses. Viruses have evolved clever strategies to establish effective infections by employing exosomes to cloak their viral genomes and gain entry into uninfected cells. While most recent exosomal studies have focused on clarifying the effect of these bioactive vesicles on viral infection, the mechanisms by which the virus regulates exosomes are still unclear and deserve further attention. This article is devoted to studying how viral components regulate exosomes biogenesis, composition, and secretion.

Characterization of Extracellular Vesicles Secreted in Lentiviral Producing HEK293SF Cell Cultures

Lentiviral vectors (LVs) are a powerful tool for gene and cell therapy and human embryonic kidney cells (HEK293) have been extensively used as a platform for production of these vectors. Like most cells and cellular tissues, HEK293 cells release extracellular vesicles (EVs). EVs released by cells share similar size, biophysical characteristics and even a biogenesis pathway with cell-produced enveloped viruses, making it a challenge to efficiently separate EVs from LVs. Thus, EVs co-purified with LVs during downstream processing, are considered “impurities” in the context of gene and cell therapy. A greater understanding of EVs co-purifying with LVs is needed to enable improved downstream processing. To that end, EVs from an inducible lentivirus producing cell line were studied under two conditions: non-induced and induced. EVs were identified in both conditions, with their presence confirmed by transmission electron microscopy and Western blot. EV cargos from each condition were then further characterized by a multi-omic approach. Nineteen proteins were identified by mass spectrometry as potential EV markers to differentiate EVs in LV preparations. Lipid composition of EV preparations before and after LV induction showed similar enrichment in phosphatidylserine. RNA cargos in EVs showed enrichment in transcripts involved in viral processes and binding functions. These findings provide insights on the product profile of lentiviral preparations and could support the development of improved separation strategies aimed at removing co-produced EVs.

Velocity Gradient Separation Reveals a New Extracellular Vesicle Population Enriched in miR-155 and Mitochondrial DNA

Extracellular vesicles (EVs) and their contents (proteins, lipids, messenger RNA, microRNA, and DNA) are viewed as intercellular signals, cell-transforming agents, and shelters for viruses that allow both diagnostic and therapeutic interventions. EVs circulating in the blood of individuals infected with human immunodeficiency virus (HIV-1) may provide insights into pathogenesis, inflammation, and disease progression. However, distinguishing plasma membrane EVs from exosomes, exomeres, apoptotic bodies, virions, and contaminating proteins remains challenging. We aimed at comparing sucrose and iodixanol density and velocity gradients along with commercial kits as a means of separating EVs from HIV particles and contaminating protein like calprotectin; and thereby evaluating the suitability of current plasma EVs analysis techniques for identifying new biomarkers of HIV-1 immune activation. Multiple analysis have been performed on HIV-1 infected cell lines, plasma from HIV-1 patients, or plasma from HIV-negative individuals spiked with HIV-1. Commercial kits, the differential centrifugation and density or velocity gradients to precipitate and separate HIV, EVs, and proteins such as calprotectin, have been used. EVs, virions, and contaminating proteins were characterized using Western blot, ELISA, RT-PCR, hydrodynamic size measurement, and enzymatic assay. Conversely to iodixanol density or velocity gradient, protein and virions co-sedimented in the same fractions of the sucrose density gradient than AChE-positive EVs. Iodixanol velocity gradient provided the optimal separation of EVs from viruses and free proteins in culture supernatants and plasma samples from a person living with HIV (PLWH) or a control and revealed a new population of large EVs enriched in microRNA miR-155 and mitochondrial DNA. Although EVs and their contents provide helpful information about several key events in HIV-1 pathogenesis, their purification and extensive characterization by velocity gradient must be investigated thoroughly before further use as biomarkers. By revealing a new population of EVs enriched in miR-155 and mitochondrial DNA, this study paves a way to increase our understanding of HIV-1 pathogenesis.

Exosomes: Small EVs with Large Immunomodulatory Effect in Glioblastoma

Glioblastomas are among the most aggressive tumors, and with low survival rates. They are characterized by the ability to create a highly immunosuppressive tumor microenvironment. Exosomes, small extracellular vesicles (EVs), mediate intercellular communication in the tumor microenvironment by transporting various biomolecules (RNA, DNA, proteins, and lipids), therefore playing a prominent role in tumor proliferation, differentiation, metastasis, and resistance to chemotherapy or radiation. Exosomes are found in all body fluids and can cross the blood-brain barrier due to their nanoscale size. Recent studies have highlighted the multiple influences of tumor-derived exosomes on immune cells. Owing to their structural and functional properties, exosomes can be an important instrument for gaining a better molecular understanding of tumors. Furthermore, they qualify not only as diagnostic and prognostic markers, but also as tools in therapies specifically targeting aggressive tumor cells, like glioblastomas.

Emerging technologies and commercial products in exosome-based cancer diagnosis and prognosis

Academic and industrial groups worldwide have reported technological advances in exosome-based cancer diagnosis and prognosis. However, the potential translation of these emerging technologies for research and clinical settings remains unknown. This work overviews the role of exosomes in cancer diagnosis and prognosis, followed by a survey on emerging exosome technologies, particularly microfluidic advances for the isolation and detection of exosomes in cancer research. The advantages and drawbacks of each of the technologies used for the isolation, detection and engineering of exosomes are evaluated to address their clinical challenges for cancer diagnosis and prognosis. Furthermore, commercial platforms for exosomal detection and analysis are introduced, and their performance and impact on cancer diagnosis and prognosis are assessed. Also, the risks associated with the further development of the next generation of exosome devices are discussed. The outcome of this work could facilitate recognizing deliverable Exo-devices and technologies with unprecedented functionality and predictable manufacturability for the next-generation of cancer diagnosis and prognosis.