Mass-spectrometry-based molecular characterization of extracellular vesicles: lipidomics and proteomics

DRAM1 increases the secretion of PKM2-enriched EVs from hepatocytes to promote macrophage activation and disease progression in ALD

DNA damage-regulated autophagy modulator 1 (DRAM1) could play important roles in inflammation and hepatic apoptosis, while its roles in alcohol-related liver disease (ALD), which is characterized by hepatic inflammation and apoptosis, are still unclear. In this study, we explored the expression, role, and mechanism of DRAM1 in ALD. Firstly, our results showed that DRAM1 was significantly increased in liver tissues of mice at the early stage of alcohol treatment. In addition, DRAM1 knockout reduced, and liver-specific overexpression of DRAM1 aggravated, alcohol-induced hepatic steatosis, injury, and expressions of M1 macrophage markers in mice. Furthermore, ethanol-induced DRAM1 of hepatic cells increased pyruvate kinase M2 (PKM2)-enriched extracellular vesicles (EVs), and ectosomes derived from hepatic cells with DRAM1 overexpression promoted macrophage activation. Mechanistic investigations showed that DRAM1 interacted with PKM2 and increased the PKM2 level in plasma membrane. At last, DRAM1 was significantly increased in liver tissues of ALD patients, and it was positively correlated with M1 macrophage markers. Taken together, this study revealed that ethanol-induced DRAM1 of hepatic cells could increase the PKM2-enriched EVs, promote macrophage activation, and aggravate the disease progression of ALD. These findings suggested that DRAM1 might be a potentially promising target for the therapy of ALD.

Technology insight: Plant-derived vesicles-How far from the clinical biotherapeutics and therapeutic drug carriers?

Within the past decades, extracellular vesicles (EVs) have emerged as important mediators of intercellular communication in both prokaryotes and higher eukaryotes to regulate a diverse range of biological processes. Besides EVs, exosome-like nanoparticles (ELNs) derived from plants were also emerging. Comparing to EVs, ELNs are source-widespread, cost-effective and easy to obtain. Their definite activities can be utilized for potential prevention/treatment of an abundance of diseases, including metabolic syndrome, cancer, colitis, alcoholic hepatitis and infectious diseases, which highlights ELNs as promising biotherapeutics. In addition, the potential of ELNs as natural or engineered drug carriers is also attractive. In this review, we tease out the timeline of plant EVs and ELNs, introduce the arising separation, purification and characterization techniques, state the stability and transport manner, discuss the therapeutic opportunities as well as the potential as novel drug carriers. Finally, the challenges and the direction of efforts to realize the clinical transformation of ELNs are also discussed.

Molecular Profile Study of Extracellular Vesicles for the Identification of Useful Small “Hit” in Cancer Diagnosis

Tumor-secreted extracellular vesicles (EVs) are the main mediators of cell-cell communication, permitting cells to exchange proteins, lipids, and metabolites in varying physiological and pathological conditions. They contain signature tumor-derived molecules that reflect the intracellular status of their cell of origin. Recent studies have shown that tumor cell-derived EVs can aid in cancer metastasis through the modulation of the tumor microenvironment, suppression of the immune system, pre-metastatic niche formation, and subsequent metastasis. EVs can easily be isolated from a variety of biological fluids, and their content makes them useful biomarkers for the diagnosis, prognosis, monitorization of cancer progression, and response to treatment. This review aims to explore the biomarkers of cancer cell-derived EVs obtained from liquid biopsies, in order to understand cancer progression and metastatic evolution for early diagnosis and precision therapy.

A New Role for Extracellular Vesicles in Cardiac Tissue Engineering and Regenerative Medicine

Cardiovascular diseases are the leading cause of death worldwide. Discovering new therapies to treat heart disease requires improved understanding of cardiac physiology at a cellular level. Extracellular vesicles (EVs) are plasma membrane-bound nano- and microparticles secreted by cells and known to play key roles in intercellular communication, often through transfer of biomolecular cargo. Advances in EV research have established techniques for EV isolation from tissue culture media or biofluids, as well as standards for quantitation and biomolecular characterization. EVs released by cardiac cells are known to be involved in regulating cardiac physiology as well as in the progression of myocardial diseases. Due to difficulty accessing the heart in vivo, advanced in vitro cardiac 'tissues-on-a-chip' have become a recent focus for studying EVs in the heart. These physiologically relevant models are producing new insight into the role of EVs in cardiac physiology and disease while providing a useful platform for screening novel EV-based therapeutics for cardiac tissue regeneration post-injury. Numerous hurdles have stalled the clinical translation of EV therapeutics for heart patients, but tissue-on-a-chip models are playing an important role in bridging the translational gap, improving mechanistic understanding of EV signalling in cardiac physiology, disease, and repair.

Exosomes in chronic respiratory diseases

Exosomes are nano-sized vesicles released by almost all cell types, with a central role as mediators of intercellular communication. In addition to physiological conditions, these extracellular vesicles seem to play a pivotal role in inflammatory processes. This assumption offers the opportunity to study exosomes as promising biomarkers and therapeutic tools for chronic respiratory disorders. Indeed, although it is well-known that at the basis of conditions like asthma, chronic obstructive pulmonary disease, alpha-1 antitrypsin deficiency and idiopathic pulmonary fibrosis there is a dysregulated inflammatory process, an unequivocal correlation between different phenotypes and their pathophysiological mechanisms has not been established yet. In this review, we report and discuss some of the most significant studies on exosomes from body fluids of subjects affected by airway diseases. Furthermore, the most widespread techniques for exosome isolation and characterization are described. Further studies are needed to answer the unresolved questions about the functional link between exosomes and chronic respiratory diseases.

Novel Quantification of Extracellular Vesicles with Unaltered Surface Membranes Using an Internalized Oligonucleotide Tracer and Applied Pharmacokinetic Multiple Compartment Modeling

PURPOSE

We developed an accessible method for labeling small extracellular vesicles (sEVs) without disrupting endogenous ligands. Using labeled sEVs administered to conscious rats, we developed a multiple compartment pharmacokinetic model to identify potential differences in the disposition of sEVs from three different cell types.

METHODS

Crude sEVs were labeled with a non-homologous oligonucleotide and isolated from cell culture media using a commercial reagent. Jugular vein catheters were used to introduce EVs to conscious rats (n = 30) and to collect blood samples. Digital PCR was leveraged to allow for quantification over a wide dynamic range. Non-linear mixed effects analysis with first order conditional estimation - extended least squares (FOCE ELS) was used to estimate population-level parameters with associated intra-animal variability.

RESULTS

86.5% ± 1.5% (mean ± S.E.) of EV particles were in the 45-195 nm size range and demonstrated protein and lipid markers of endosomal origin. Incorporated oligonucleotide was stable in blood and detectable over five half-lives. Data were best described by a three-compartment model with one elimination from the central compartment. We performed an observation-based simulated posterior predictive evaluation with prediction-corrected visual predictive check. Covariate and bootstrap analyses identified cell type having an influence on peripheral volumes (V2 and V3) and clearance (Cl3).

CONCLUSIONS

Our method relies upon established laboratory techniques, can be tailored to a variety of biological questions regarding the pharmacokinetic disposition of extracellular vesicles, and will provide a complementary approach for the of study EV ligand-receptor interactions in the context of EV uptake and targeted therapeutics.

Shotgun-based proteomics of extracellular vesicles in Alzheimer's disease reveals biomarkers involved in immunological and coagulation pathways

Alzheimer's disease (AD) is the most common form of dementia and without readily available clinical biomarkers. Blood-derived proteins are routinely used for diagnostics; however, comprehensive plasma profiling is challenging due to the dynamic range in protein concentrations. Extracellular vesicles (EVs) can cross the blood-brain barrier and may provide a source for AD biomarkers. We investigated plasma-derived EV proteins for AD biomarkers from 10 AD patients, 10 Mild Cognitive Impairment (MCI) patients, and 9 healthy controls (Con) using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The ultracentrifuged EVs were washed and confirmed according to the MISEV2018 guidelines. Some AD patients presented with highly elevated FXIIIA1 (log₂ FC: 4.6, p-value: 0.005) and FXIIIB (log₂ FC: 4.9, p-value: 0.018). A panel of proteins was identified discriminating Con from AD (AUC: 0.91, CI: 0.67-1.00) with ORM2 (AUC: 1.00, CI: 1.00-1.00), RBP4 (AUC: 0.99, CI: 0.95-1.00), and HYDIN (AUC: 0.89, CI: 0.72-1.00) were found especially relevant for AD. This indicates that EVs provide an easily accessible matrix for possible AD biomarkers. Some of the MCI patients, with similar protein profiles as the AD group, progressed to AD within a 2-year timespan.

The Power of Extracellular Vesicles in Myeloproliferative Neoplasms: "Crafting" a Microenvironment That Matters

Myeloproliferative Neoplasms (MPN) are acquired clonal disorders of the hematopoietic stem cells and include Essential Thrombocythemia, Polycythemia Vera and Myelofibrosis. MPN are characterized by mutations in three driver genes (JAK2, CALR and MPL) and by a state of chronic inflammation. Notably, MPN patients experience increased risk of thrombosis, disease progression, second neoplasia and evolution to acute leukemia. Extracellular vesicles (EVs) are a heterogeneous population of microparticles with a role in cell-cell communication. The EV-mediated cross-talk occurs via the trafficking of bioactive molecules such as nucleic acids, proteins, metabolites and lipids. Growing interest is focused on EVs and their potential impact on the regulation of blood cancers. Overall, EVs have been suggested to orchestrate the complex interplay between tumor cells and the microenvironment with a pivotal role in "education" and "crafting" of the microenvironment by regulating angiogenesis, coagulation, immune escape and drug resistance of tumors. This review is focused on the role of EVs in MPN. Specifically, we will provide an overview of recent findings on the involvement of EVs in MPN pathogenesis and discuss opportunities for their potential application as diagnostic and prognostic biomarkers.

Exosomes: Potential Disease Biomarkers and New Therapeutic Targets

Exosomes are extracellular vesicles released by cells, both constitutively and after cell activation, and are present in different types of biological fluid. Exosomes are involved in the pathogenesis of diseases, such as cancer, neurodegenerative diseases, pregnancy disorders and cardiovascular diseases, and have emerged as potential non-invasive biomarkers for the detection, prognosis and therapeutics of a myriad of diseases. In this review, we describe recent advances related to the regulatory mechanisms of exosome biogenesis, release and molecular composition, as well as their role in health and disease, and their potential use as disease biomarkers and therapeutic targets. In addition, the advantages and disadvantages of their main isolation methods, characterization and cargo analysis, as well as the experimental methods used for exosome-mediated drug delivery, are discussed. Finally, we present potential perspectives for the use of exosomes in future clinical practice.

Role of adipocyte-derived extracellular vesicles in vascular inflammation

Extracellular vesicles (EVs) are nanometre-sized vesicles released from most cells, including adipocytes. Relatively little is known about adipocyte-derived EVs (ADEVs) in comparison to other EV subtypes, though interest in ADEVs as potential paracrine and endocrine communicators of adipose tissue in obesity is building. Current evidence indicates that ADEVs contribute to the development of adipose tissue dysfunction; a key feature of obese adipose tissue that it is associated with obesity-related comorbidities including cardiovascular disease (CVD). This review summarises our current knowledge of ADEVs in the development of adipose tissue dysfunction and the potential of ADEVs to disrupt redox signalling and exert vascular effects that may exacerbate CVD in obesity.

Implications and pitfalls for cancer diagnostics exploiting extracellular vesicles

Early detection of cancer in order to facilitate timely therapeutic interventions is an unsolved problem in today's clinical diagnostics. Tumors are detected so far mostly after pathological symptoms have emerged (usually already in progressed disease states), within preventive screenings, or occasionally as incidental finding. The emergence of extracellular vesicle (EV) analytics in combination with liquid biopsy sampling opened a plethora of new possibilities for the detection of tumors (and other diseases). This review gives an overview of the diversity of currently known EV species and the relevant cargo molecules representing potential biomarkers to detect, identify and characterize tumor cells. A number of molecules reported in recent years to be valuable targets for different aspects of cancer diagnostics, are presented. Furthermore, we discuss (technical) challenges and pitfalls related to the various potential applications (screening, diagnosis, prognosis, monitoring) of liquid biopsy based EV analytics, and give an outlook to possible future directions of this emerging field in oncology.

Multiple functions of pyruvate kinase M2 in various cell types

Glucose metabolism is a mechanism by which energy is produced in form of adenosine triphosphate (ATP) by mitochondria and precursor metabolites are supplied to enable the ultimate enrichment of mature metabolites in the cell. Recently, glycolytic enzymes have been shown to have unconventional but important functions. Among these enzymes, pyruvate kinase M2 (PKM2) plays several roles including having conventional metabolic enzyme activity, and also being a transcriptional regulator and a protein kinase. Compared with the closely related PKM1, PKM2 is highly expressed in cancer cells and embryos, whereas PKM1 is dominant in mature, differentiated cells. Posttranslational modifications such as phosphorylation and acetylation of PKM2 change its cellular functions. In particular, PKM2 can translocate to the nucleus, where it regulates the transcription of many target genes. It is notable that PKM2 also acts as a protein kinase to phosphorylate several substrate proteins. Besides cancer cells and embryonic cells, astrocytes also highly express PKM2, which is crucial for lactate production via expression of lactate dehydrogenase A (LDHA), while mature neurons predominantly express PKM1. The lactate produced in cancer cells promotes tumor progress and that in astrocytes can be supplied to neurons and may act as a major source for neuronal ATP energy production. Thereby, we propose that PKM2 along with its different posttranslational modifications has specific purposes for a variety of cell types, performing unique functions.

Ruminant Milk-Derived Extracellular Vesicles: A Nutritional and Therapeutic Opportunity?

Milk has been shown to contain a specific fraction of extracellular particles that are reported to resist digestion and are purposefully packaged with lipids, proteins, and nucleic acids to exert specific biological effects. These findings suggest that these particles may have a role in the quality of infant nutrition, particularly in the early phase of life when many of the foundations of an infant's potential for health and overall wellness are established. However, much of the current research focuses on human or cow milk only, and there is a knowledge gap in how milk from other species, which may be more commonly consumed in different regions, could also have these reported biological effects. Our review provides a summary of the studies into the extracellular particle fraction of milk from a wider range of ruminants and pseudo-ruminants, focusing on how this fraction is isolated and characterised, the stability and uptake of the fraction, and the reported biological effects of these fractions in a range of model systems. As the individual composition of milk from different species is known to differ, we propose that the extracellular particle fraction of milk from non-traditional and minority species may also have important and distinct biological properties that warrant further study.

Extracellular Vesicles in Non-alcoholic Fatty Liver Disease and Alcoholic Liver Disease

As the largest vital solid organ in the body, liver is consisting of multiple types of cells including hepatocytes, Kupffer cell, hepatic stellate cells (HSCs), liver sinusoidal endothelial cells (LSECs), and other immune cells. The communication between these cells is critical in maintaining liver function homeostasis, and dysregulation of such communication contributes to the pathogenesis of various liver diseases. Extracellular vesicles (EVs), including exosomes and ectosomes, act as important mediators of cell-to-cell communication. EVs can be produced and uptaken by a wide range of cells including all types of cells in the liver. Growing evidences show that EVs are involved in the development of liver diseases, especially non-alcoholic fatty liver disease (NAFLD) and alcoholic liver disease (ALD). In this review, we will summarize recent advance in how EVs production are altered in NAFLD and ALD and how the changes of EVs quantity and cargos influence the progression of these diseases. The therapeutic and diagnostic potential of EVs in NAFLD and ALD will be also discussed in this review.

Extracellular vesicles as a next-generation drug delivery platform

Extracellular-vesicle-based cell-to-cell communication is conserved across all kingdoms of life. There is compelling evidence that extracellular vesicles are involved in major (patho)physiological processes, including cellular homoeostasis, infection propagation, cancer development and cardiovascular diseases. Various studies suggest that extracellular vesicles have several advantages over conventional synthetic carriers, opening new frontiers for modern drug delivery. Despite extensive research, clinical translation of extracellular-vesicle-based therapies remains challenging. Here, we discuss the uniqueness of extracellular vesicles along with critical design and development steps required to utilize their full potential as drug carriers, including loading methods, in-depth characterization and large-scale manufacturing. We compare the prospects of extracellular vesicles with those of the well established liposomes and provide guidelines to direct the process of developing vesicle-based drug delivery systems.

Potential Use of Exosomes as Diagnostic Biomarkers and in Targeted Drug Delivery: Progress in Clinical and Preclinical Applications

Exosomes are cell-derived vesicles containing heterogeneous active biomolecules such as proteins, lipids, mRNAs, receptors, immune regulatory molecules, and nucleic acids. They typically range in size from 30 to 150 nm in diameter. An exosome's surfaces can be bioengineered with antibodies, fluorescent dye, peptides, and tailored for small molecule and large active biologics. Exosomes have enormous potential as a drug delivery vehicle due to enhanced biocompatibility, excellent payload capability, and reduced immunogenicity compared to alternative polymeric-based carriers. Because of active targeting and specificity, exosomes are capable of delivering their cargo to exosome-recipient cells. Additionally, exosomes can potentially act as early stage disease diagnostic tools as the exosome carries various protein biomarkers associated with a specific disease. In this review, we summarize recent progress on exosome composition, biological characterization, and isolation techniques. Finally, we outline the exosome's clinical applications and preclinical advancement to provide an outlook on the importance of exosomes for use in targeted drug delivery, biomarker study, and vaccine development.

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.

The Mystery of Red Blood Cells Extracellular Vesicles in Sleep Apnea with Metabolic Dysfunction

Sleep is very important for overall health and quality of life, while sleep disorder has been associated with several human diseases, namely cardiovascular, metabolic, cognitive, and cancer-related alterations. Obstructive sleep apnea (OSA) is the most common respiratory sleep-disordered breathing, which is caused by the recurrent collapse of the upper airway during sleep. OSA has emerged as a major public health problem and increasing evidence suggests that untreated OSA can lead to the development of various diseases including neurodegenerative diseases. In addition, OSA may lead to decreased blood oxygenation and fragmentation of the sleep cycle. The formation of free radicals or reactive oxygen species (ROS) can emerge and react with nitric oxide (NO) to produce peroxynitrite, thereby diminishing the bioavailability of NO. Hypoxia, the hallmark of OSA, refers to a decline of tissue oxygen saturation and affects several types of cells, playing cell-to-cell communication a vital role in the outcome of this interplay. Red blood cells (RBCs) are considered transporters of oxygen and nutrients to the tissues, and these RBCs are important interorgan communication systems with additional functions, including participation in the control of systemic NO metabolism, redox regulation, blood rheology, and viscosity. RBCs have been shown to induce endothelial dysfunction and increase cardiac injury. The mechanistic links between changes of RBC functional properties and cardiovascular are largely unknown. Extracellular vesicles (EVs) are secreted by most cell types and released in biological fluids both under physiological and pathological conditions. EVs are involved in intercellular communication by transferring complex cargoes including proteins, lipids, and nucleic acids from donor cells to recipient cells. Advancing our knowledge about mechanisms of RBC-EVs formation and their pathophysiological relevance may help to shed light on circulating EVs and to translate their application to clinical practice. We will focus on the potential use of RBC-EVs as valuable diagnostic and prognostic biomarkers and state-specific cargoes, and possibilities as therapeutic vehicles for drug and gene delivery. The use of RBC-EVs as a precision medicine for the diagnosis and treatment of the patient with sleep disorder will improve the prognosis and the quality of life in patients with cardiovascular disease (CVD).

Bacterial Membrane Vesicles in Pneumonia: From Mediators of Virulence to Innovative Vaccine Candidates

Pneumonia due to respiratory infection with most prominently bacteria, but also viruses, fungi, or parasites is the leading cause of death worldwide among all infectious disease in both adults and infants. The introduction of modern antibiotic treatment regimens and vaccine strategies has helped to lower the burden of bacterial pneumonia, yet due to the unavailability or refusal of vaccines and antimicrobials in parts of the global population, the rise of multidrug resistant pathogens, and high fatality rates even in patients treated with appropriate antibiotics pneumonia remains a global threat. As such, a better understanding of pathogen virulence on the one, and the development of innovative vaccine strategies on the other hand are once again in dire need in the perennial fight of men against microbes. Recent data show that the secretome of bacteria consists not only of soluble mediators of virulence but also to a significant proportion of extracellular vesicles—lipid bilayer-delimited particles that form integral mediators of intercellular communication. Extracellular vesicles are released from cells of all kinds of organisms, including both Gram-negative and Gram-positive bacteria in which case they are commonly termed outer membrane vesicles (OMVs) and membrane vesicles (MVs), respectively. (O)MVs can trigger inflammatory responses to specific pathogens including S. pneumonia, P. aeruginosa, and L. pneumophila and as such, mediate bacterial virulence in pneumonia by challenging the host respiratory epithelium and cellular and humoral immunity. In parallel, however, (O)MVs have recently emerged as auspicious vaccine candidates due to their natural antigenicity and favorable biochemical properties. First studies highlight the efficacy of such vaccines in animal models exposed to (O)MVs from B. pertussis, S. pneumoniae, A. baumannii, and K. pneumoniae. An advanced and balanced recognition of both the detrimental effects of (O)MVs and their immunogenic potential could pave the way to novel treatment strategies in pneumonia and effective preventive approaches.

Recent advances on protein-based quantification of extracellular vesicles

Extracellular vesicles (EVs) are secreted by almost all cells into the circulatory system and have the important function of intercellular communication. Ranging in size from 50 to 1000 nm, they are further classified based on origin, size, physical properties and function. EVs have shown the potential for studying various physiological and pathological processes, such as characterizing their parent cells with molecular markers that could further signify diseases. Proteins within EVs are the building blocks for the vesicles to function within a biological system. Isolation and proteomic profiling of EVs can advance the understanding of their biogenesis and functions, which can give further insight of how they can be used in clinical settings. However, the nanoscale size of EVs, which is much smaller than that of cells, comprises a major challenge for EV isolation and the characterization of their protein cargos. With the recent advances of bioanalytical techniques such as lab-on-a-chip devices and innovated flow cytometry, the quantification of EV proteins from a small number of vesicles down to the single vesicle level has been achieved, shining light on the promising applications of these small vesicles for early disease diagnosis and treatment monitoring. In this article, we first briefly review conventional EV protein determination technologies and their limitations, followed by detailed description and analysis of emerging technologies used for EV protein quantification, including optical, non-optical, microfluidic, and single vesicle detection methods. The pros and cons of these technologies are compared and the current challenges are outlined. Future perspectives and potential research directions of the EV protein analysis methods are discussed.

Cell-to-Cell Communication by Host-Released Extracellular Vesicles in the Gut: Implications in Health and Disease

Communication between cells is crucial to preserve body homeostasis and health. Tightly controlled intercellular dialog is particularly relevant in the gut, where cells of the intestinal mucosa are constantly exposed to millions of microbes that have great impact on intestinal homeostasis by controlling barrier and immune functions. Recent knowledge involves extracellular vesicles (EVs) as mediators of such communication by transferring messenger bioactive molecules including proteins, lipids, and miRNAs between cells and tissues. The specific functions of EVs principally depend on the internal cargo, which upon delivery to target cells trigger signal events that modulate cellular functions. The vesicular cargo is greatly influenced by genetic, pathological, and environmental factors. This finding provides the basis for investigating potential clinical applications of EVs as therapeutic targets or diagnostic biomarkers. Here, we review current knowledge on the biogenesis and cargo composition of EVs in general terms. We then focus the attention to EVs released by cells of the intestinal mucosa and their impact on intestinal homeostasis in health and disease. We specifically highlight their role on epithelial barrier integrity, wound healing of epithelial cells, immunity, and microbiota shaping. Microbiota-derived EVs are not reviewed here.

High-Sensitivity Glycan Profiling of Blood-Derived Immunoglobulin G, Plasma, and Extracellular Vesicle Isolates with Capillary Zone Electrophoresis-Mass Spectrometry

We developed a highly sensitive method for profiling of N-glycans released from proteins based on capillary zone electrophoresis coupled to electrospray ionization mass spectrometry (CZE-ESI-MS) and applied the technique to glycan analysis of plasma and blood-derived isolates. The combination of dopant-enriched nitrogen (DEN)-gas introduced into the nanoelectrospray microenvironment with optimized ionization, desolvation, and CZE-MS conditions improved the detection sensitivity up to ∼100-fold, as directly compared to the conventional mode of instrument operation through peak intensity measurements. Analyses without supplemental pressure increased the resolution ∼7-fold in the separation of closely related and isobaric glycans. The developed method was evaluated for qualitative and quantitative glycan profiling of three types of blood isolates: plasma, total serum immunoglobulin G (IgG), and total plasma extracellular vesicles (EVs). The comparative glycan analysis of IgG and EV isolates and total plasma was conducted for the first time and resulted in detection of >200, >400, and >500 N-glycans for injected sample amounts equivalent to <500 nL of blood. Structural CZE-MS² analysis resulted in the identification of highly diverse glycans, assignment of α-2,6-linked sialic acids, and differentiation of positional isomers. Unmatched depth of N-glycan profiling was achieved compared to previously reported methods for the analysis of minute amounts of similar complexity blood isolates.

Extracellular Vesicles in Liquid Biopsies: Potential for Disease Diagnosis

Liquid biopsy is conducted through minimally invasive or noninvasive procedures, and the resulting material can be subjected to genomic, proteomic, and lipidomic analyses for early diagnosis of cancers and other diseases. Extracellular vesicles (EVs), one kind of promising tool for liquid biopsy, are nanosized bilayer particles that are secreted by all kinds of cells and that carry cargoes such as lipids, proteins, and nucleic acids, protecting them from enzymatic degradation in the extracellular environment. In this review, we provide a comprehensive introduction to the properties and applications of EVs, including their biogenesis, contents, sample collection, isolation, and applications in diagnostics based on liquid biopsy.

Experimental and Biological Insights from Proteomic Analyses of Extracellular Vesicle Cargos in Normalcy and Disease

Extracellular vesicles (EVs) offer a vehicle for diagnostic and therapeutic utility. EVs carry bioactive cargo and an accrued interest in their characterization has emerged. Efforts at identifying EV-enriched protein or RNA led to a surprising realization that EVs are excessively heterogeneous in nature. This diversity is originally attributed to vesicle sizes but it is becoming evident that different classes of EVs vehiculate distinct molecular cargos. Therefore, one of the current challenges in EV research is their selective isolation in quantities sufficient for efficient downstream analyses. Many protocols have been developed; however, reproducibility between research groups can be difficult to reach and inter-studies analyses of data from different isolation protocols are unmanageable. Therefore, there is an unmet need to optimize and standardize methods and protocols for the isolation and purification of EVs. This review focuses on the diverse techniques and protocols used over the years to isolate and purify EVs with a special emphasis on their adequacy for proteomics applications. By combining recent advances in specific isolation methods that yield superior quality of EV preparations and mass spectrometry techniques, the field is now prepared for transformative advancements in establishing distinct categorization and cargo identification of subpopulations based on EV surface markers.

The Biological Function of Extracellular Vesicles during Fertilization, Early Embryo-Maternal Crosstalk and Their Involvement in Reproduction: Review and Overview

Secretory extracellular vesicles (EVs) are membrane-enclosed microparticles that mediate cell to cell communication in proximity to, or distant from, the cell of origin. Cells release a heterogeneous spectrum of EVs depending on their physiologic and metabolic state. Extracellular vesicles are generally classified as either exosomes or microvesicles depending on their size and biogenesis. Extracellular vesicles mediate temporal and spatial interaction during many events in sexual reproduction and supporting embryo-maternal dialogue. Although many omic technologies provide detailed understanding of the molecular cargo of EVs, the difficulty in obtaining populations of homogeneous EVs makes difficult to interpret the molecular profile of the molecules derived from a miscellaneous EV population. Notwithstanding, molecular characterization of EVs isolated in physiological and pathological conditions may increase our understanding of reproductive and obstetric diseases and assist the search for potential non-invasive biomarkers. Moreover, a more precise vision of the cocktail of biomolecules inside the EVs mediating communication between the embryo and mother could provide new insights to optimize the therapeutic action and safety of EV use.

Extracellular vesicles from organoids and 3D culture systems

When discovered, extracellular vesicles (EVs) such as exosomes were thought of as junk carriers and a means by which the cell disposed of its waste material. Over the years, the role of EVs in cell communication has become apparent with the discovery that the nano-scale vesicles also transport RNA, DNA, and other bioactive components to and from the cells. These findings were originally made in EVs from body fluids of organisms and from in vitro two-dimensional (2D) cell culture models. Recently, organoids and other 3D multicellular in vitro models are being used to study EVs in the context of both physiologic and pathological states. However, standard, reproducible methods are lacking for EV analysis using these models. As a step toward understanding the implications of these platforms, this review provides a comprehensive picture of the progress using 3D in vitro culture models for EV analysis. Translational efforts and regulatory considerations for EV therapeutics are also briefly overviewed to understand what is needed for scale-up and, ultimately, commercialization.

Extracellular Vesicles in Essential Hypertension: Hidden Messengers

PURPOSE OF REVIEW

Hypertension affects about half of all Americans, yet in the vast majority of cases, the factors causing the hypertension cannot be clearly delineated. Developing a more precise understanding of the molecular pathogenesis of HTN and its various phenotypes is therefore a pressing priority. Circulating and urinary extracellular vesicles (EVs) are potential novel candidates as biomarkers and bioactivators in HTN. EVs are a heterogeneous population of small membrane fragments shed from various cell types into various body fluids. As EVs carry protein, RNA, and lipids, they also play a role as effectors and novel cell-to-cell communicators. In this review, we discuss the diagnostic, functional, and regenerative role of EVs in essential HTN and focus on EV protein and RNA cargo as the most extensively studied EV cargo.

RECENT FINDINGS

The field of EVs in HTN is still a young one and earlier studies have not used the novel EV detection tools currently available. More rigor and transparency in EV research are needed. Current data suggest that EVs represent potential novel biomarkers in HTN. EVs correlate with HTN severity and possibly end-organ damage. However, it has yet to be discerned which specific subtype(s) of EV reflects best HTN pathophysiology. Evolving studies are also showing that EVs might be novel regulators in vascular and renal tubular function and also be therapeutic. RNA in EVs has been studied in the context of hypertension, largely in the form of studies of miRNA, which are reviewed herein. Beyond miRNAs, mRNA in urinary EVs changed in response to sodium loading in humans. EVs represent promising novel biomarkers and bioactivators in essential HTN. Novel tools are being developed to apply more rigor in EV research including more in vivo models and translation to humans.

Exosomes in cancer

Exosomes are small extracellular vesicles released by cells under physiological and pathological conditions. There is emerging evidence associating exosomes with tumorigenesis. They carry cargo (DNA, RNA, miRNA and protein) pertaining to the cell of origin and play a key role in intercellular communication, influencing several cellular processes. Moreover, exosomes can be shed and found in almost all body fluids, providing a source of biomarkers for tumor diagnosis and prognosis. In addition, the use of exosomes for cancer therapeutics is another research area that is gaining attention. This book chapter aims to explore the role of exosomes in tumor biogenesis, progression and clinical applications, comprehensively compiling the research for three tumor types, namely head and neck cancer, lung cancer and glioblastoma.

Tracking of Tumor Cell-Derived Extracellular Vesicles In Vivo Reveals a Specific Distribution Pattern with Consecutive Biological Effects on Target Sites of Metastasis

PURPOSE

Extracellular vesicles, small vesicles carrying inter alia proteins, miRNA and RNA, are important mediators of intercellular communication. The purpose of this study was to assess the distribution of extracellular vesicles from highly malignant breast cancer and their subsequent effect on the immune cell infiltrate in target organs of metastasis.

PROCEDURES

Extracellular vesicles were isolated from the tissue culture supernatant of highly malignant 4T1 breast cancer cells or the serum of healthy BALB/c mice. The purity of the isolate was verified by electron microscopy and western blotting. Extracellular vesicles were additionally subjected to proteome analysis. After labeling with the fluorescent dye DiR, extracellular vesicles were injected into healthy BALB/c mice and their in vivo distribution was assessed using fluorescence reflectance imaging (FRI). Following ex vivo imaging of the organs, lung tissue samples were analyzed for extracellular vesicle-mediated changes of myeloid cells and T cell numbers, using flow cytometry. Proteome analysis revealed major differences in the cargo of tumor cell-derived versus extracellular vesicles from healthy serum.

RESULTS

In contrast to control extracellular vesicles, DiR-labeled extracellular vesicles from tumor cells preferentially accumulated in lung, liver, and spine. Subsequent flow cytometry of the immune cell composition of lung tissue samples revealed an increase of cytotoxic CD8+ T cells and a decrease of CD4+ T-helper cells as well as an increase in mature macrophages in response to tumor cell EV.

CONCLUSIONS

In conclusion, distribution of tumor cell-derived extracellular vesicles follows a specific pattern and can be monitored, using dedicated imaging. Extracellular vesicles alter the immune cell composition in target organs of metastasis, using a specific proteome cargo.

Characterizing Extracellular Vesicles and Their Diverse RNA Contents

Cells release nanometer-scale, lipid bilayer-enclosed biomolecular packages (extracellular vesicles; EVs) into their surrounding environment. EVs are hypothesized to be intercellular communication agents that regulate physiological states by transporting biomolecules between near and distant cells. The research community has consistently advocated for the importance of RNA contents in EVs by demonstrating that: (1) EV-related RNA contents can be detected in a liquid biopsy, (2) disease states significantly alter EV-related RNA contents, and (3) sensitive and specific liquid biopsies can be implemented in precision medicine settings by measuring EV-derived RNA contents. Furthermore, EVs have medical potential beyond diagnostics. Both natural and engineered EVs are being investigated for therapeutic applications such as regenerative medicine and as drug delivery agents. This review focuses specifically on EV characterization, analysis of their RNA content, and their functional implications. The NIH extracellular RNA communication (ERC) program has catapulted human EV research from an RNA profiling standpoint by standardizing the pipeline for working with EV transcriptomics data, and creating a centralized database for the scientific community. There are currently thousands of RNA-sequencing profiles hosted on the Extracellular RNA Atlas alone (Murillo et al., 2019), encompassing a variety of human biofluid types and health conditions. While a number of significant discoveries have been made through these studies individually, integrative analyses of these data have thus far been limited. A primary focus of the ERC program over the next five years is to bring higher resolution tools to the EV research community so that investigators can isolate and analyze EV sub-populations, and ultimately single EVs sourced from discrete cell types, tissues, and complex biofluids. Higher resolution techniques will be essential for evaluating the roles of circulating EVs at a level which impacts clinical decision making. We expect that advances in microfluidic technologies will drive near-term innovation and discoveries about the diverse RNA contents of EVs. Long-term translation of EV-based RNA profiling into a mainstay medical diagnostic tool will depend upon identifying robust patterns of circulating genetic material that correlate with a change in health status.

Novel Blood-Derived Extracellular Vesicle-Based Biomarkers in Alzheimer's Disease Identified by Proximity Extension Assay

Easily accessible biomarkers for Alzheimer's dementia (AD) are lacking and established clinical markers are limited in applicability. Blood is a common biofluid for biomarker discoveries, and extracellular vesicles (EVs) may provide a matrix for exploring AD related biomarkers. Thus, we investigated proteins related to neurological and inflammatory processes in plasma and EVs. By proximity extension assay (PEA), 182 proteins were measured in plasma and EVs from patients with AD (n = 10), Mild Cognitive Impairment (MCI, n = 10), and healthy controls (n = 10). Plasma-derived EVs were enriched by 20,000× g, 1 h, 4 °C, and confirmed using nanoparticle tracking analysis (NTA), western blotting, and transmission electron microscopy with immunolabelling (IEM). Presence of CD9+ EVs was confirmed by western blotting and IEM. No group differences in particle concentration or size were detected by NTA. However, significant protein profiles were observed among subjects, particularly for EVs. Several proteins and their ratios could distinguish cognitively affected from healthy individuals. For plasma TGF-α│CCL20 (AUC = 0.96, 95% CI = 0.88-1.00, p = 0.001) and EVs CLEC1B│CCL11 (AUC = 0.95, 95% CI = 0.86-1.00, p = 0.001) showed diagnostic capabilities. Using PEA, we identified protein profiles capable of distinguishing healthy controls from AD patients. EVs provided additional biological information related to AD not observed in plasma alone.

A Comprehensive Proteomic SWATH-MS Workflow for Profiling Blood Extracellular Vesicles: A New Avenue for Glioma Tumour Surveillance

Improving outcomes for diffuse glioma patients requires methods that can accurately and sensitively monitor tumour activity and treatment response. Extracellular vesicles (EV) are membranous nanoparticles that can traverse the blood-brain-barrier, carrying oncogenic molecules into the circulation. Measuring clinically relevant glioma biomarkers cargoed in circulating EVs could revolutionise how glioma patients are managed. Despite their suitability for biomarker discovery, the co-isolation of highly abundant complex blood proteins has hindered comprehensive proteomic studies of circulating-EVs. Plasma-EVs isolated from pre-operative glioma grade II-IV patients (n = 41) and controls (n = 11) were sequenced by Sequential window acquisition of all theoretical fragment ion spectra mass spectrometry (SWATH-MS) and data extraction was performed by aligning against a custom 8662-protein library. Overall, 4054 proteins were measured in plasma-EVs. Differentially expressed proteins and putative circulating-EV markers were identified (adj. p-value < 0.05), including those reported in previous in-vitro and ex-vivo glioma-EV studies. Principal component analysis showed that plasma-EV protein profiles clustered according to glioma histological-subtype and grade, and plasma-EVs resampled from patients with recurrent tumour progression grouped with more aggressive glioma samples. The extensive plasma-EV proteome profiles achieved here highlight the potential for SWATH-MS to define circulating-EV biomarkers for objective blood-based measurements of glioma activity that could serve as ideal surrogate endpoints to assess tumour progression and allow more dynamic, patient-centred treatment protocols.

Combination of Size-Exclusion Chromatography and Ultracentrifugation Improves the Proteomic Profiling of Plasma-Derived Small Extracellular Vesicles

Background

Circulating small extracellular vesicles (sEVs) and its associated proteins are of great interest in the early detection of many diseases. However, there is no gold standard for plasma sEVs isolation, especially for proteomic profiling which could be largely affected by contamination such as lipoproteins and plasma proteins. Previous studies suggested combinations of different sEVs isolation methods could improve the yield and purity of the isolated fractions. Nevertheless, there is no systematic evaluation of size-exclusion chromatography (SEC), ultracentrifugation (UC), and their combination in a proteomic perspective.

Results

Plasma samples were collected from healthy individuals, and sEVs were separated by one-step SEC, one-step UC, and combining SEC with UC, respectively. Here we exhibited that the purity of sEVs was improved by SEC in contrast to traditional UC. Furthermore, by conducting a SEC procedure followed by UC, we separated sEVs with the highest purity. In the proteomic analysis, 992 protein species were identified in the plasma sEVs isolated by our novel separation method, of which several proteins are sEVs-associated proteins but hitherto never been identified in the previous studies and database, much more than plasma sEVs isolated by UC (453) or SEC (682) alone. As compared to Vesiclepedia and Exocarta databases, plasma sEVs isolated by the new procedure kept 584 previously identified sEVs-associated proteins and 360 other proteins that have not been detected before. Detailed analysis suggested that more kinds of sEVs biomarkers, such as CD9, ALIX, and FLOT1, could be identified in plasma sEVs isolated by the novel isolation method as compared to one-step UC/SEC. Furthermore, the lower abundance ranks of common contaminants, such as lipoproteins and IgG chains, in the sEVs fractions obtained by our new method as compared to one-step UC/SEC also demonstrated the purity of sEVs had been improved.

Conclusions

Combining SEC with UC could significantly improve the performance of mass spectrometry-based proteomic profiling in analyzing plasma-derived sEVs.

Technologies and Standardization in Research on Extracellular Vesicles

Extracellular vesicles (EVs) are phospholipid bilayer membrane-enclosed structures containing RNAs, proteins, lipids, metabolites, and other molecules, secreted by various cells into physiological fluids. EV-mediated transfer of biomolecules is a critical component of a variety of physiological and pathological processes. Potential applications of EVs in novel diagnostic and therapeutic strategies have brought increasing attention. However, EV research remains highly challenging due to the inherently complex biogenesis of EVs and their vast heterogeneity in size, composition, and origin. There is a need for the establishment of standardized methods that address EV heterogeneity and sources of pre-analytical and analytical variability in EV studies. Here, we review technologies developed for EV isolation and characterization and discuss paths toward standardization in EV research.

The Roles of Exosomes in Visual and Auditory Systems

Exosomes are nanoscale membrane-enclosed vesicles 30-150 nm in diameter that are originated from a number of type cells by the endocytic pathway and consist of proteins, lipids, RNA, and DNA. Although, exosomes were initially considered to be cellular waste, they have gradually been recognized to join in cell-cell communication and cell signal transmission. In addition, exosomal contents can be applied as biomarkers for clinical judgment and exosomes can as potential carriers in a novel drug delivery system. Unfortunately, purification methods of exosomes remain an obstacle. We described some common purification methods and highlight Morpho Menelaus (M. Menelaus) butterfly wings can be developed as efficient methods for exosome isolation. Furthermore, the current research on exosomes mainly focused on their roles in cancer, while related studies on exosomes in the visual and auditory systems are limited. Here we reviewed the biogenesis and contents of exosomes. And more importantly, we summarized the roles of exosomes and provided prospective for exosome research in the visual and auditory systems.

THE PRESENT AND FUTURE OF THE MASS SPECTROMETRY-BASED INVESTIGATION OF THE EXOSOME LANDSCAPE

Exosomes are critical intercellular messengers released upon the fusion of multivesicular bodies with the cellular plasma membrane that deliver their cargo in the form of extracellular vesicles. Containing numerous nonrandomly packed functional proteins, lipids, and RNAs, exosomes are vital intercellular messengers that contribute to the physiologic processes of the healthy organism. During the post-genome era, exosome-oriented proteomics have garnered great interest. Since its establishment, mass spectrometry (MS) has been indispensable for the field of proteomics research and has advanced rapidly to interrogate biological samples at a higher resolution and sensitivity. Driven by new methodologies and more advanced instrumentation, MS-based approaches have revolutionized our understanding of protein biology. As the access to online proteomics database platforms has blossomed, experimental data processing occurs with more speed and accuracy. Here, we review recent advances in the technological progress of MS-based proteomics and several new detection strategies for MS-based proteomics research. We also summarize the use of integrated online databases for proteomics research in the era of big data. © 2020 John Wiley & Sons Ltd. Mass Spec Rev.

Targeting endothelial exosomes for the prevention of cardiovascular disease

Exosomes are small lipid bilayer-enclosed 30-140 nm diameter vesicles formed from endosomes. Exosomes are secreted by various cell types including endothelial cells, immune cells and other cardiovascular tissues, and they can be detected in plasma, urine, cerebrospinal fluid, as well as tissues. Exosomes were initially regarded as a disposal mechanism to discard unwanted materials from cells. Recent studies suggest that exosomes play an important role in mediating of intercellular communication through the delivery and transport of cellular components such as nucleic acids, lipids, and proteins and thus regulate cardiovascular disease. Further, the underlying mechanisms by which abnormally released exosomes promote cardiovascular disease are not well understood. This review highlights recent studies involving endothelial exosomes, gives a brief overview of exosome biogenesis and release, isolation and identification of exosomes, and provides a contemporary understanding of the endothelial exosome pathophysiology and potential therapeutic strategies.

Extracellular vesicles and melatonin benefit embryonic develop by regulating reactive oxygen species and 5-methylcytosine

Embryo culture conditions are crucial as they can affect embryo quality and even offspring. Oviductal extracellular vesicles (EVs) long been considered a major factor influencing interactions between the oviduct and embryos, and thus its absence is associated with inferior embryonic development in in vitro culture. Herein, we demonstrated that melatonin is present in oviduct fluids and oviduct fluid-derived EVs. Addition of either EVs (1.87 × 10¹¹ particles/mL) or melatonin (340 ng/mL) led to a significant downregulation of reactive oxygen species (ROS) and 5-methylcytosine (5-mC), as well as an increase in the blastocyst rate of embryos, which was inhibited by the addition of luzindole-a melatonin receptor agonist. A combination of EVs (1.87 × 10¹⁰ particles/mL) and melatonin (at 34.3 pg/mL) led to the same results as well as a significant decrease in the apoptosis index and increase in the inner cell mass (ICM)/trophectoderm (TE) index. These results suggest that an EV-melatonin treatment benefits embryonic development. Our findings provide insights into the role of EVs and melatonin during cell communication and provide new evidence of the communication between embryos and maternal oviduct.

Combined Morpho-Chemical Profiling of Individual Extracellular Vesicles and Functional Nanoparticles without Labels

Biological nanoparticles are important targets of study, yet their small size and tendency to aggregate makes their heterogeneity difficult to profile on a truly single-particle basis. Here we present a label-free system called 'Raman-enabled nanoparticle trapping analysis' (R-NTA) that optically traps individual nanoparticles, records Raman spectra and tracks particle motion to identify chemical composition, size, and refractive index. R-NTA has the unique capacity to characterize aggregation status and absolute chemical concentration at the single-particle level. We validate the method on NIST standards and liposomes, demonstrating that R-NTA can accurately characterize size and chemical heterogeneity, including determining combined morpho-chemical properties such as the number of lamellae in individual liposomes. Applied to extracellular vesicles (EVs), we find distinct differences between EVs from cancerous and noncancerous cells, and that knockdown of the TRPP2 ion channel, which is pathologically highly expressed in laryngeal cancer cells, leads the EVs to more closely resemble EVs from normal epithelial cells. Intriguingly, the differences in EV content are found in small subpopulations of EVs, highlighting the importance of single-particle measurements. These experiments demonstrate the power of the R-NTA system to measure and characterize the morpho-chemical heterogeneity of bionanoparticles.

Extracellular Vesicles Derived From Mesenchymal Stem Cells (MSC) in Regenerative Medicine: Applications in Skin Wound Healing

The cells secrete extracellular vesicles (EV) that may have an endosomal origin, or from evaginations of the plasma membrane. The former are usually called exosomes, with sizes ranging from 50 to 100 nm. These EV contain a lipid bilayer associated to membrane proteins. Molecules such as nucleic acids (DNA, mRNA, miRNA, lncRNA, etc.) and proteins may be stored inside. The EV composition depends on the producer cell type and its physiological conditions. Through them, the cells modify their microenvironment and the behavior of neighboring cells. That is accomplished by transferring factors that modulate different metabolic and signaling pathways. Due to their properties, EV can be applied as a diagnostic and therapeutic tool in medicine. The mesenchymal stromal cells (MSC) have immunomodulatory properties and a high regenerative capacity. These features are linked to their paracrine activity and EV secretion. Therefore, research on exosomes produced by MSC has been intensified for use in cell-free regenerative medicine. In this area, the use of EV for the treatment of chronic skin ulcers (CSU) has been proposed. Such sores occur when normal healing does not resolve properly. That is usually due to excessive prolongation of the inflammatory phase. These ulcers are associated with aging and diseases, such as diabetes, so their prevalence is increasing with the one of such latter disease, mainly in developed countries. This has very important socio-economic repercussions. In this review, we show that the application of MSC-derived EV for the treatment of CSU has positive effects, including accelerating healing and decreasing scar formation. This is because the EV have immunosuppressive and immunomodulatory properties. Likewise, they have the ability to activate the angiogenesis, proliferation, migration, and differentiation of the main cell types involved in skin regeneration. They include endothelial cells, fibroblasts, and keratinocytes. Most of the studies carried out so far are preclinical. Therefore, there is a need to advance more in the knowledge about the conditions of production, isolation, and action mechanisms of EV. Interestingly, their potential application in the treatment of CSU opens the door for the design of new highly effective therapeutic strategies.

Extracellular Vesicles Could Carry an Evolutionary Footprint in Interkingdom Communication

Extracellular vesicles (EVs) are minute particles secreted by the cells of living organisms. Although the functional role of EVs is not yet clear, recent work has highlighted their role in intercellular communication. Here, we expand on this view by suggesting that EVs can also mediate communication among interacting organisms such as hosts, pathogens and vectors. This inter-kingdom communication via EVs is likely to have important evolutionary consequences ranging from adaptation of parasites to specialized niches in the host, to host resistance and evolution and maintenance of parasite virulence and transmissibility. A potential system to explore these consequences is the interaction among the human host, the mosquito vector and Plasmodium parasite involved in the malaria disease. Indeed, recent studies have found that EVs derived from Plasmodium infected red blood cells in humans are likely mediating the parasite's transition from the asexual to sexual stage, which might facilitate transmission to the mosquito vector. However, more work is needed to establish the adaptive consequences of this EV signaling among different taxa. We suggest that an integrative molecular approach, including a comparative phylogenetic analysis of the molecules (e.g., proteins and nucleic acids) derived from the EVs of interacting organisms (and their closely-related species) in the malaria system will prove useful for understanding interkingdom communication. Such analyses will also shed light on the evolution and persistence of host, parasite and vector interactions, with implications for the control of vector borne infectious diseases.

The binding of SLE autoantibodies to mitochondria

Systemic lupus erythematosus (SLE) is a prototypic autoimmune disease characterized by immune complexes. Because these complexes contain mitochondrial components, we assessed the presence of antibodies to whole mitochondria (wMITO) using an ELISA in which mitochondria from mouse liver are bound to microtiter plates pre-coated with poly-l-lysine. Studies with this ELISA demonstrated that SLE plasmas contain abundant anti-wMITO activity. While digestion with DNase 1 did not affect anti-wMITO activity, adsorption of plasma on DNA affinity columns could reduce binding activity. Assay for anti-mitochondrial antibodies (AMA) by immunofluorescence and an ELISA with the M2 antigen (2-oxo-acid dehydrogenase protein complex) showed a low frequency of positivity, indicating that AMA and anti-wMITO are distinct specificities. In the study of 204 patients with SLE, the levels of anti-wMITO were higher in active SLE and correlated with levels of anti-DNA. These findings suggest that anti-wMITO can form immune complexes with mitochondria which may drive pathogenesis.

Charge Detection Mass Spectrometry Measurements of Exosomes and other Extracellular Particles Enriched from Bovine Milk

The masses of particles in a bovine milk extracellular vesicle (EV) preparation enriched for exosomes were directly determined for the first time by charge detection mass spectrometry (CDMS). In CDMS, both the mass-to-charge ratio (m/z) and z are determined simultaneously for individual particles, enabling mass determinations for particles that are far beyond the mass limit (∼1.0 MDa) of conventional mass spectrometry (MS). Particle masses and charges span a wide range from m ∼ 2 to ∼90 MDa and z ∼ 50 to ∼1300 e (elementary charges) and are highly dependent upon the conditions used to extract and isolate the EVs. EV particles span a continuum of masses, reflecting the highly heterogeneous nature of these samples. However, evidence for unique populations of particles is obtained from correlation of the charges and masses. An analysis that uses a two-dimensional Gaussian model, provides evidence for six families of particles, four of which having masses in the range expected for exosomes. Complementary proteomics measurements and electron microscopy (EM) imaging are used to further characterize the EVs and confirm that these samples have been enriched in exosomes. The ability to characterize such extremely heterogeneous mixtures of large particles with rapid, sensitive, and high-resolution MS techniques is critical to ongoing analytical efforts to separate and purify exosomes and exosome subpopulations. Direct measurement of each particle's mass and charge is a new means of characterizing the physical and chemical properties of exosomes and other EVs.

miR-221-3p Delivered by BMMSC-Derived Microvesicles Promotes the Development of Acute Myelocytic Leukemia

Objective: The study aims to investigate the effects of miR-221-3p in bone marrow mesenchymal stem cell (BMMSC)-derived microvesicles (MVs) on cell cycle, proliferation and invasion of acute myelocytic leukemia (AML).

Methods: Bioinformatics was used to predict differentially expressed miRNAs (DEmiRNAs) in AML. The morphology of BMMSC-derived MVs was observed under an electron microscope, and the positional relation of MVs and OCI-AML2 cells was observed by a fluorescence microscope. MTT, Transwell, and flow cytometry assays were used to analyze the effects of MVs on OCI-AML2 cells. The targeted relationship between miR-221-3p and CDKN1C was detected by dual luciferase assay.

Results: It was verified that miR-221-3p promoted the proliferation, invasion and migration of OCI-AML2 cells, and induced the cell cycle arrest in G1/S phase as well as inhibited cell apoptosis. Further studies showed that MVs promoted the proliferation, migration and invasion of AML, and induced the cell cycle arrest in G1/S phase through miR-221-3p. It was confirmed that miR-221-3p can directly target CDKN1C to regulate cell cycle, proliferation and invasion of AML.

Conclusion: miR-221-3p in BMMSC-derived MVs regulated AML cell cycle, cell proliferation and invasion through targeting CDKN1C. miR-221-3p and CDKN1C were considered to be potential targets and biomarkers for the treatment of AML in clinic.

Secreted Pyruvate Kinase M2 Promotes Lung Cancer Metastasis through Activating the Integrin Beta1/FAK Signaling Pathway

Cancer cell-derived secretomes have been documented to play critical roles in cancer progression. Intriguingly, alternative extracellular roles of intracellular proteins are involved in various steps of tumor progression, which can offer strategies to fight cancer. Herein, we identify lung cancer progression-associated secretome signatures using mass spectrometry analysis. Among them, PKM2 is verified to be highly expressed and secreted in lung cancer cells and clinical samples. Functional analyses demonstrates that secreted PKM2 facilitates tumor metastasis. Furthermore, mass spectrometry analysis and functional validation identify integrin β1 as a receptor of secreted PKM2. Mechanistically, secreted PKM2 directly bound to integrin β1 and subsequently activated the FAK/SRC/ERK axis to promote tumor metastasis. Collectively, our findings suggest that PKM2 is a potential serum biomarker for diagnosing lung cancer and that targeting the secreted PKM2-integrin β1 axis can inhibit lung cancer development, which provides evidence of a potential therapeutic strategy in lung cancer.

The changing face of pulmonary hypertension diagnosis: a historical perspective on the influence of diagnostics and biomarkers

Pulmonary hypertension is a complex, multifactorial disease that results in right heart failure and premature death. Since the initial reports of pulmonary hypertension in the late 1800s, the diagnosis of pulmonary hypertension has evolved with respect to its definition, screening tools, and diagnostic techniques. This historical perspective traces the earliest roots of pulmonary hypertension detection and diagnosis through to the current recommendations for classification. We highlight the diagnostic tools used in the past and present, and end with a focus on the future directions of early detection. Early detection of pulmonary hypertension and pulmonary arterial hypertension and the proper determination of etiology are vital for the early therapeutic intervention that can prolong life expectancy and improve quality of life. The search for a non-invasive screening tool for the identification and classification of pulmonary hypertension is ongoing, and we discuss the role of animal models of the disease in this search.