Enlargeosome traffic: exocytosis triggered by various signals is followed by endocytosis, membrane shedding or both

Fluorescent, phosphorescent, magnetic resonance contrast and radioactive tracer labelling of extracellular vesicles

This review focusses on the significance of fluorescent, phosphorescent labelling and tracking of extracellular vesicles (EVs) for unravelling their biology, pathophysiology, and potential diagnostic and therapeutic uses. Various labeling strategies, such as lipid membrane, surface protein, luminal, nucleic acid, radionuclide, quantum dot labels, and metal complex-based stains, are evaluated for visualizing and characterizing EVs. Direct labelling with fluorescent lipophilic dyes is simple but generally lacks specificity, while surface protein labelling offers selectivity but may affect EV-cell interactions. Luminal and nucleic acid labelling strategies have their own advantages and challenges. Each labelling approach has strengths and weaknesses, which require a suitable probe and technique based on research goals, but new tetranuclear polypyridylruthenium(II) complexes as phosphorescent probes have strong phosphorescence, selective staining, and stability. Future research should prioritize the design of novel fluorescent probes and labelling platforms that can significantly enhance the efficiency, accuracy, and specificity of EV labeling, while preserving their composition and functionality. It is crucial to reduce false positive signals and explore the potential of multimodal imaging techniques to gain comprehensive insights into EVs.

Silencing AHNAK promotes nasopharyngeal carcinoma progression by upregulating the ANXA2 protein

PURPOSE

Nasopharyngeal carcinoma (NPC) is an aggressive head and neck disease with a high incidence of distant metastases. Enlargeosomes are cytoplasmic organelles marked by, desmoyokin/AHNAK. This study aimed to evaluate the expression of AHNAK in NPC and its effect on enlargeosomes and to investigate the correlation between AHNAK expression levels and clinical NPC patient characteristics.

METHODS

Primary nasopharyngeal carcinoma (NPC) and NPC specimens were evaluated by analyzing public data, and immunohistochemistry. Systematic in vitro and in vivo experiments were performed using different NPC-derived cell lines and mouse models.

RESULTS

In this study, we detected AHNAK and Annexin A2(ANXA2), a protein coating the surface of enlargeosomes, in NPC samples. We found that AHNAK was down-regulated. Down-regulation of AHNAK was associated with poor overall survival in NPC patients. Moreover, transcription factor FOSL1-mediated transcriptional repression was responsible for the low expression of AHNAK by recruiting EZH2. Whereas Annexin A2 was upregulated in human NPC tissues. Upregulation of Annexin A2 was associated with lymph node metastasis and distant metastasis in NPC patients. Functional studies confirmed that silencing of AHNAK enhanced the growth, invasion, and metastatic properties of NPC cells both in vitro and in vivo. In terms of mechanism, loss of AHNAK led to an increase of annexin A2 protein level in NPC cells. Silencing ANXA2 restored NPC cells' migrative and invasive ability upon loss of AHNAK.

CONCLUSION

Here, we report AHNAK as a tumor suppressor in NPC, which may act through annexin A2 oncogenic signaling in enlargeosome, with potential implications for novel approaches to NPC treatment.

Cells Responding to Closely Related Cholesterol-Dependent Cytolysins Release Extracellular Vesicles with a Common Proteomic Content Including Membrane Repair Proteins

The plasma membrane (PM) protects cells from extracellular threats and supports cellular homeostasis. Some pathogens produce pore-forming toxins (PFTs) that disrupt PM integrity by forming transmembrane pores. High PFT concentrations cause massive damage leading to cell death and facilitating infection. Sub-lytic PFT doses activate repair mechanisms to restore PM integrity, support cell survival and limit disease. Shedding of extracellular vesicles (EVs) has been proposed as a key mechanism to eliminate PFT pores and restore PM integrity. We show here that cholesterol-dependent cytolysins (CDCs), a specific family of PFTs, are at least partially eliminated through EVs release, and we hypothesize that proteins important for PM repair might be included in EVs shed by cells during repair. To identify new PM repair proteins, we collected EVs released by cells challenged with sub-lytic doses of two different bacterial CDCs, listeriolysin O and pneumolysin, and determined the EV proteomic repertoire by LC-MS/MS. Intoxicated cells release similar EVs irrespectively of the CDC used. Also, they release more and larger EVs than non-intoxicated cells. A cluster of 70 proteins including calcium-binding proteins, molecular chaperones, cytoskeletal, scaffold and membrane trafficking proteins, was detected enriched in EVs collected from intoxicated cells. While some of these proteins have well-characterized roles in repair, the involvement of others requires further study. As proof of concept, we show here that Copine-1 and Copine-3, proteins abundantly detected in EVs released by intoxicated cells, are required for efficient repair of CDC-induced PM damage. Additionally, we reveal here new proteins potentially involved in PM repair and give new insights into common mechanisms and machinery engaged by cells in response to PM damage.

Actin Cytoskeletal Dynamics in Single-Cell Wound Repair

The plasma membrane protects the eukaryotic cell from its surroundings and is essential for cell viability; thus, it is crucial that membrane disruptions are repaired quickly to prevent immediate dyshomeostasis and cell death. Accordingly, cells have developed efficient repair mechanisms to rapidly reseal ruptures and reestablish membrane integrity. The cortical actin cytoskeleton plays an instrumental role in both plasma membrane resealing and restructuring in response to damage. Actin directly aids membrane repair or indirectly assists auxiliary repair mechanisms. Studies investigating single-cell wound repair have often focused on the recruitment and activation of specialized repair machinery, despite the undeniable need for rapid and dynamic cortical actin modulation; thus, the role of the cortical actin cytoskeleton during wound repair has received limited attention. This review aims to provide a comprehensive overview of membrane repair mechanisms directly or indirectly involving cortical actin cytoskeletal remodeling.

The Role of Extracellular Vesicles from Human Macrophages on Host-Pathogen Interaction

The nano-sized membrane enclosed extracellular vesicles (EVs) released by virtually all cell types play an essential role in intercellular communication via delivering bio-molecules, such as nucleic acids, proteins, lipids, and other molecules to recipient cells. By mediating an active and steady-state cell-to-cell communication, EVs contribute to regulating and preserving cellular homeostasis. On the other hand, EVs can also spread pathogen-derived molecules during infections, subverting the host immune responses during infections and thus worsening pathophysiological processes. In recent years, the biological functioning of EVs has become a widespread research field in basic and clinical branches of medical sciences due to their potential role in therapeutic applications for several diseases. This review aims to summarize the main recent findings regarding the implication of EVs shed by human macrophages (MΦ-EVs) and how they can modulate the host immune response to control or increase the damage caused by infectious agents. We will also present the methods used to describe MΦ-EVs, as well as the potential of these EVs as disease diagnostic tools for some human pathogens. We believe that an in-depth understanding of the host–pathogen interactions mediated by MΦ-EVs may trigger the development of innovative therapeutic strategies against infectious diseases.

Skeletal Muscle Cell Growth Alters the Lipid Composition of Extracellular Vesicles

We sought to characterize the lipid profile of skeletal muscle cell-derived Extracellular Vesicles (EVs) to determine if a hypertrophic stimulus would affect the lipid composition of C2C12 myotube-derived EVs. Analyses included C2C12 murine myoblasts differentiated into myotubes and treated with Insulin-Like Growth Factor 1 (IGF-1) for 24 h to induce hypertrophic growth. EVs were isolated from cell culture media, quantified using Nanoparticle Tracking Analysis (NTA) and analyzed using Transmission Electron Microscopy (TEM). EVs were homogenized and lipids extracted for quantification by Mass Spectrometry followed by downstream lipid class enrichment and lipid chain analysis. IGF-1 treatment elicited an increase in CD63 and CD81 levels (39% and 21%) compared to the controls (16%), respectively. Analysis revealed that skeletal muscle-derived EVs are enriched in bioactive lipids that are likely selectively incorporated into EVs during hypertrophic growth. IGF-1 treatment of myotubes had a significant impact on the levels of diacylglycerol (DG) and ceramide (Cer) in secreted EVs. Specifically, the proportion of unsaturated DG was two- to three-fold higher in EVs derived from IGF-treated cells, as compared to those from control cells. The levels of saturated DG were unaffected. Selective increases were similarly seen in C16- and C24-Cer but not in other species. Levels of free sphingoid bases tended to decrease, while those of sphingosine-1-phosphate was unaffected. Our results suggest that the lipid composition and biogenesis of skeletal muscle-derived EVs, are specific and highly selective during hypertrophic growth.

Polarized cells display asymmetric release of extracellular vesicles

Extracellular vesicles (EVs), a broad term for the lipid microparticles known as microvesicles and exosomes, are discharged by cells into their surrounding space. Microvesicles are discharged upon outward plasma membrane budding, while exosomes are secreted after multivesicular body (MVB) fusion with the plasma membrane. The majority of information regarding EV biology comes from studies performed in non-polarized cells. Here we characterize EV release in polarized cells. We found a substantial asymmetry in the number and composition of EVs produced and released from the apical membrane of epithelial cells as compared to the basolateral membrane. We showed that the quantitative difference is related to the polarized distribution of two phosphoinositide species between the two cell surfaces and that the peculiar biochemical composition of resultant EVs reflects their site of origin. In particular, apical and basolateral exosomes may derive from distinct classes of MVBs originating from and fusing with the same plasma membrane. We identify VAMP8/Endobrevin as a regulator of the basolateral release of exosomes, whereas the mechanism responsible for apical EV release requires further study.

Characterization and internalization of small extracellular vesicles released by human primary macrophages derived from circulating monocytes

Extracellular vesicles (EVs) are small membrane-limited structures derived from outward budding of the plasma membrane or endosomal system that participate in cellular communication processes through the transport of bioactive molecules to recipient cells. To date, there are no published methodological works showing step-by-step the isolation, characterization and internalization of small EVs secreted by human primary macrophages derived from circulating monocytes (MDM-derived sEVs). Thus, here we aimed to provide an alternative protocol based on differential ultracentrifugation (dUC) to describe small EVs (sEVs) from these cells. Monocyte-derived macrophages were cultured in EV-free medium during 24, 48 or 72 h and, then, EVs were isolated from culture supernatants by (dUC). Macrophages secreted a large amount of sEVs in the first 24 h, with size ranging from 40-150 nm, peaking at 105 nm, as evaluated by nanoparticle tracking analysis and scanning electron microscopy. The markers Alix, CD63 and CD81 were detected by immunoblotting in EV samples, and the co-localization of CD63 and CD81 after sucrose density gradient ultracentrifugation (S-DGUC) indicated the presence of sEVs from late endosomal origin. Confocal fluorescence revealed that the sEVs were internalized by primary macrophages after three hours of co-culture. The methodology here applied aims to contribute for enhancing reproducibility between the limited number of available protocols for the isolation and characterization of MDM-derived sEVs, thus providing basic knowledge in the area of EV methods that can be useful for those investigators working with sEVs released by human primary macrophages derived from circulating monocytes.

Mesenchymal and Induced Pluripotent Stem Cells-Derived Extracellular Vesicles: The New Frontier for Regenerative Medicine?

Regenerative medicine aims to repair damaged, tissues or organs for the treatment of various diseases, which have been poorly managed with conventional drugs and medical procedures. To date, multimodal regenerative methods include transplant of healthy organs, tissues, or cells, body stimulation to activate a self-healing response in damaged tissues, as well as the combined use of cells and bio-degradable scaffold to obtain functional tissues. Certainly, stem cells are promising tools in regenerative medicine due to their ability to induce de novo tissue formation and/or promote organ repair and regeneration. Currently, several studies have shown that the beneficial stem cell effects, especially for mesenchymal stem cells (MSCs) and induced pluripotent stem cells (iPSCs) in damaged tissue restore are not dependent on their engraftment and differentiation on the injury site, but rather to their paracrine activity. It is now well known that paracrine action of stem cells is due to their ability to release extracellular vesicles (EVs). EVs play a fundamental role in cell-to-cell communication and are directly involved in tissue regeneration. In the present review, we tried to summarize the molecular mechanisms through which MSCs and iPSCs-derived EVs carry out their therapeutic action and their possible application for the treatment of several diseases.

The role of extracellular vesicles in skeletal muscle and systematic adaptation to exercise

Regular exercise has a central role in human health by reducing the risk of type 2 diabetes, obesity, stroke and cancer. How exercise is able to promote such systemic benefits has remained somewhat of a mystery but has been thought to be in part mediated by the release of myokines, skeletal muscle-specific cytokines, in response to exercise. Recent studies have revealed skeletal muscle can also release extracellular vesicles (EVs) into circulation following a bout of exercise. EVs are small membrane-bound vesicles capable of delivering biomolecules to recipient cells and subsequently altering their metabolism. The notion that EVs may have a role in both skeletal muscle and systemic adaptation to exercise has generated a great deal of excitement within a number of different fields including exercise physiology, neuroscience and metabolism. The purpose of this review is to provide an introduction to EV biology and what is currently known about skeletal muscle EVs and their potential role in the response of muscle and other tissues to exercise.

AHNAK C-Terminal Peptide Membrane Binding-Interactions between the Residues 5654-5673 of AHNAK and Phospholipid Monolayers and Bilayers

The dysferlin membrane repair complex contains a small complex, S100A10-annexin A2, which initiates membrane repair by recruiting the protein AHNAK to the membrane, where it interacts via binding sites in the C-terminal region. However, no molecular data are available for the membrane binding of the various proteins involved in this complex. Therefore, the present study investigated the membrane binding of AHNAK to elucidate its role in the cell membrane repair process. A chemically synthesized peptide (pAHNAK), comprising the 20 amino acids in the C-terminal domain of AHNAK, was applied to Langmuir monolayer models, and the binding parameters and insertion angles were measured with surface tensiometry and ellipsometry. The interaction of pAHNAK with lipid bilayers was studied using ³¹P solid-state nuclear magnetic resonance. pAHNAK preferentially and strongly interacted with phospholipids that comprised negatively charged polar head groups with unsaturated lipids. This finding provides a better understanding of AHNAK membrane behavior and the parameters that influence its function in membrane repair.

Cancer-Derived Extracellular Vesicle-Associated MicroRNAs in Intercellular Communication: One Cell's Trash Is Another Cell's Treasure

Several non-protein-coding genomic regions, previously marked as "junk DNA", have been reported to be transcriptionally active, giving rise to non-coding RNA species implicated in fundamental biological and pathological processes. In particular, microRNAs (miRNAs), a class of small non-coding RNAs mediating post-transcriptional gene silencing, are causally involved in several human diseases, including various cancer types. Extracellular vesicles (EVs) are membranous structures physiologically released by most cell types. Initially, they were considered a "waste-removal" mechanism, through which cells could dispose unnecessary material and organelles. It is now widely demonstrated that EVs also play a critical role in intercellular communication, mediating the horizontal transfer of lipids, proteins, and genetic material. A paradigm shift in the biology of miRNAs was represented by the discovery that EVs, especially from cancer cells, contain miRs. EV-associated miRs act as autocrine, paracrine and endocrine factors, participating in cancer pathogenesis by modulating intercellular communication. Noteworthy, these formerly neglected molecules are now considered the next generation of cancer "theranostic" tools, with strong clinical relevance. In this review, we aim to summarize the most recent findings regarding EV-associated miRs in cancer pathogenesis and in the development of novel anti-neoplastic diagnostic and therapeutic approaches.

Exosomes: Current use and future applications

Exosomes are endosomal-derived vesicles that play a critical role in cell-to-cell communication and are secreted in several biological fluids including serum, saliva, urine, ascites, and cerebro-spinal fluid amongst others. Exosomes are small (30-150 nm diameter) with a distinctive bilipid protein structure. They can carry and exchange various cargos between cells and are used as a non-invasive biomarker for several diseases. Exosomes are considered the best biomarkers for cancer diagnosis, owing to their unique characteristics. Here, we provide a review of the up-to-date applications of exosomes, derived from various sources, in the prognosis and diagnosis of several diseases including cancer, cardiovascular and regenerative diseases as well as, arthritis, neurological diseases, and diabetes mellitus. The role of exosomes and their applications in biomedical research and preclinical trials have also been briefly discussed.

Emerging role of extracellular vesicles in the regulation of skeletal muscle adaptation

Extracellular vesicles (EVs) were initially characterized as "garbage bags" with the purpose of removing unwanted material from cells. It is now becoming clear that EVs mediate intercellular communication between distant cells through a transfer of genetic material, a process important to the systemic adaptation in physiological and pathological conditions. Although speculative, it has been suggested that the majority of EVs that make it into the bloodstream would be coming from skeletal muscle, since it is one of the largest organs in the human body. Although it is well established that skeletal muscle secretes peptides (currently known as myokines) into the bloodstream, the notion that skeletal muscle releases EVs is in its infancy. Besides intercellular communication and systemic adaptation, EV release could represent the mechanism by which muscle adapts to certain stimuli. This review summarizes the current understanding of EV biology and biogenesis and current isolation methods and briefly discusses the possible role EVs have in regulating skeletal muscle mass.

Oxygen tension modulates extracellular vesicles and its miRNA contents in bovine embryo culture medium

The biotechnology for in vitro embryo production is becoming increasingly popular, being applied to humans and domestic animals. Embryo development can be achieved with either 20% or 5% oxygen tension. The extracellular vesicles (EVs) are secreted by different cell types and carry bioactive materials. Our objective was to determine the secretion pattern and micro RNA (miRNA) contents of EVs released in the bovine embryo culture environment-embryo and cumulus cell monolayer-on Days 3 and 7 of in vitro culture under two different oxygen tensions: High (20%) and low (5%). The EVs were isolated from the medium and analyzed to determine size, concentration, and miRNA levels. EVs concentration in low oxygen tension increased on Day 3 and decreased on Day 7. Additionally, altered EV miRNAs derived from the embryo-cumulus culture medium were predicted to regulate survival and proliferation-related pathways on Days 3 and 7. Moreover, miR-210 levels decreased in EVs isolated from the culture medium under high oxygen tension suggesting that this miRNA can be used as a marker for normoxia since it is associated with low oxygen tension. In summary, this study provides knowledge of the oxygen tension effects on EVs release and content, and potentially, on cell-to-cell communication during in vitro bovine embryo production.

Glycan Profiling Analysis of Equine Amniotic Progenitor Mesenchymal Cells and Their Derived Extracellular Microvesicles

Equine amniotic mesenchymal cells (eAMCs) are involved in many mechanisms in tissue regenerative processes. Their secreted vesicles are important effectors in a wide array of biological processes, and contribute to in vivo healing of equine tendon lesions and endometrial inflammation. Glycoconjugates are involved in cellular recognition and in the efficient uptake of extracellular vesicles (EVs) by recipient cells. In this study, we evaluated the surface glycosylation pattern of eAMCs and their EVs from the eAMCs released in conditioned medium. We used a microarray procedure in which eAMCs and eAMC-EVs were spotted on microarray slides, and incubated with a panel of 14 biotinylated lectins and Cy3-conjugated streptavidin. Signal intensity was detected using a microarray scanner. Both eAMC and eAMC-EV microarrays interacted with all the lectins, indicating the presence of N- and O-linked glycans. With respect to eAMCs, eAMC-EVs, were found to be (1) enriched in Galβ1,3GalNAc terminating O-glycans, α2,3-linked sialoglycans, and high-mannose N-glycans (Con A); (2) diminished in N-acetyllactosamine, GalNAc, Gal, GlcNAc, and fucose terminating glycans; and (3) unchanged in α2,6 linked sialoglycans content. These results suggest that eAMC-EVs emerge from a specific eAMC microdomain, and that the high simultaneous presence of Galβ1,3GalNAc, α2,3 sialic acid, and high-mannose N-linked glycans may constitute markers of the eAMC-EVs. The role of these sugars in equine regenerative medicine requires further investigation.

TMEM16F activation by Ca2+ triggers plasma membrane expansion and directs PD-1 trafficking

TMEM16F is a Ca2+ -gated ion channel that is required for Ca2+ -activated phosphatidylserine exposure on the surface of many eukaryotic cells. TMEM16F is widely expressed and has roles in platelet activation during blood clotting, bone formation and T cell activation. By combining microscopy and patch clamp recording we demonstrate that activation of TMEM16F by Ca2+ ionophores in Jurkat T cells triggers large-scale surface membrane expansion in parallel with phospholipid scrambling. With continued ionophore application,TMEM16F-expressing cells then undergo extensive shedding of ectosomes. The T cell co-receptor PD-1 is selectively incorporated into ectosomes. This selectivity depends on its transmembrane sequence. Surprisingly, cells lacking TMEM16F not only fail to expand surface membrane in response to elevated cytoplasmic Ca2+, but instead undergo rapid massive endocytosis with PD-1 internalisation. These results establish a new role for TMEM16F as a regulator of Ca2+ activated membrane trafficking.

Exosomes and Exosome-Inspired Vesicles for Targeted Drug Delivery

The similarities between exosomes and liposomes, together with the high organotropism of several types of exosomes, have recently prompted the development of engineered-exosomes or exosome-mimetics, which may be artificial (liposomal) or cell-derived vesicles, as advanced platforms for targeted drug delivery. Here, we provide the current state-of-the-art of using exosome or exosome-inspired systems for drug delivery. We review the various approaches investigated and the shortcomings of each approach. Finally the challenges which have been identified to date in this field are summarized.

Lab-on-Chip for Exosomes and Microvesicles Detection and Characterization

Interest in extracellular vesicles and in particular microvesicles and exosomes, which are constitutively produced by cells, is on the rise for their huge potential as biomarkers in a high number of disorders and pathologies as they are considered as carriers of information among cells, as well as being responsible for the spreading of diseases. Current methods of analysis of microvesicles and exosomes do not fulfill the requirements for their in-depth investigation and the complete exploitation of their diagnostic and prognostic value. Lab-on-chip methods have the potential and capabilities to bridge this gap and the technology is mature enough to provide all the necessary steps for a completely automated analysis of extracellular vesicles in body fluids. In this paper we provide an overview of the biological role of extracellular vesicles, standard biochemical methods of analysis and their limits, and a survey of lab-on-chip methods that are able to meet the needs of a deeper exploitation of these biological entities to drive their use in common clinical practice.

Differential Expression of Keratinocyte-Derived Extracellular Vesicle Mirnas Discriminate Exosomes From Apoptotic Bodies and Microvesicles

Extracellular vesicles (EVs) are mammalian cell-derived nano-scale structures enclosed by a lipid bilayer that were previously considered to be cell debris with little biological value. However, EVs are now recognized to possess biological function, acting as a packaging, transport and delivery mechanisms by which functional molecules (i.e., miRNAs) can be transferred to target cells over some distance. To examine the miRNA from keratinocyte-derived EVs, we isolated three distinct populations of EVs from both HaCaT and primary human keratinocytes (PKCs) and characterized their biophysical, biochemical and functional features by using microscopy, immunoblotting, nanoparticle tracking, and next generation sequencing. We identified 1,048; 906; and 704 miRNAs, respectively, in apoptotic bodies (APs), microvesicles (MVs) and exosomes (EXs) released from HaCaT, and 608; 506; and 622 miRNAs in APs, MVs and EXs released from PKCs. In which, there were 623 and 437 identified miRNAs common to three HaCaT-derived EVs and PKC-derived EVs, respectively. In addition, we found hundreds of exosomal miRNAs that were previously un-reported. Differences in the abundance levels of the identified EV miRNAs could discriminate between the three EV populations. These data contribute substantially to knowledge within the EV-identified miRNA database, especially with regard to keratinocyte-derived EV miRNA content.

Extracellular Vesicles, Ageing, and Therapeutic Interventions

A more comprehensive understanding of the human ageing process is required to help mitigate the increasing burden of age-related morbidities in a rapidly growing global demographic of elderly individuals. One exciting novel strategy that has emerged to intervene involves the use of extracellular vesicles to engender tissue regeneration. Specifically, this employs their molecular payloads to confer changes in the epigenetic landscape of ageing cells and ameliorate the loss of functional capacity. Understanding the biology of extracellular vesicles and the specific roles they play during normative ageing will allow for the development of novel cell-free therapeutic interventions. Hence, the purpose of this review is to summarise the current understanding of the mechanisms that drive ageing, critically explore how extracellular vesicles affect ageing processes and discuss their therapeutic potential to mitigate the effects of age-associated morbidities and improve the human health span.

Extracellular vesicles as modulators of wound healing

Impaired healing of cutaneous wounds and ulcers continues to have a major impact on the quality of life of millions of people. In recent years, the capacity for stem and progenitor cells to promote wound repair has been investigated with evidence that secreted factors are responsible for the observed therapeutic benefits. This review addresses current evidence in support of stem/progenitor cell-derived extracellular vesicles (EVs) as a regenerative therapy for acceleration of wound healing. Encouraging results for local or systemic administration of EVs have been reported in a range of clinically-relevant animal models of cutaneous wounds. Furthermore, a number of plausible mechanisms involving EV-mediated transfer of proteins and RNAs that trigger pro-repair pathways in target cells have been demonstrated experimentally. However, for successful clinical translation in the coming years, further emphasis on standardized experimental protocols, detailed methodological reporting and clear definition of EV-based therapeutic products will be required.

Annexin A2-mediated cancer progression and therapeutic resistance in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a head and neck cancer with poor clinical outcomes and insufficient treatments in Southeast Asian populations. Although concurrent chemoradiotherapy has improved recovery rates of patients, poor overall survival and low efficacy are still critical problems. To improve the therapeutic efficacy, we focused on a tumor-associated protein called Annexin A2 (ANXA2). This review summarizes the mechanisms by which ANXA2 promotes cancer progression (e.g., proliferation, migration, the epithelial-mesenchymal transition, invasion, and cancer stem cell formation) and therapeutic resistance (e.g., radiotherapy, chemotherapy, and immunotherapy). These mechanisms gave us a deeper understanding of the molecular aspects of cancer progression, and further provided us with a great opportunity to overcome therapeutic resistance of NPC and other cancers with high ANXA2 expression by developing this prospective ANXA2-targeted therapy.

Exosomal miRNAs as novel cancer biomarkers: Challenges and opportunities

A biomarker with high specificity and sensitivity, is a basic requirement for non-invasive cancer diagnosis. Exosomes are a type of lipid bilayer extracellular vesicles (EVs), containing different components, including proteins, lipids, DNA, messenger RNA (mRNA), and non-coding RNAs. Increasing evidence indicates that nucleic acids are protected by exosome lipid membrane. These vesicles are almost released from all cell types, into biological fluids. In cancer, the expression of microRNAs (miRNAs), located in the tumor cell-derived exosomes, is deregulated and it could be led to metastasis and therapy resistance. Due to the presence of exosomes in various body fluids and the stability of miRNAs in exosomes, exosomal miRNAs can provide a new class of biomarkers for early and minimally invasive cancer diagnosis. In this article, we review the miRNAs and their roles in cancer. Furthermore, we explain the different types of EVs, especially exosomes, and their functional roles in cancer. At the end, we discuss about the importance of exosomal miRNAs for cancer diagnosis. As well as, we briefly summarize the exosome isolation techniques and obstacles, limiting the clinical applications of exosomal miRNAs.

AHNAK enables mammary carcinoma cells to produce extracellular vesicles that increase neighboring fibroblast cell motility

Extracellular vesicles play important roles in tumor development. Many components of these structures, including microvesicles and exosomes, have been defined. However, mechanisms by which extracellular vesicles affect tumor progression are not fully understood. Here, we investigated vesicular communication between mammary carcinoma cells and neighboring nontransformed mammary fibroblasts. Nonbiased proteomic analysis found that over 1% of the entire proteome is represented in these vesicles, with the neuroblast differentiation associated protein AHNAK and annexin A2 being the most abundant. In particular, AHNAK was found to be the most prominent component of these vesicles based on peptide number, and appeared necessary for their formation. In addition, we report here that carcinoma cells produce vesicles that promote the migration of recipient fibroblasts. These data suggest that AHNAK enables mammary carcinoma cells to produce and release extracellular vesicles that cause disruption of the stroma by surrounding fibroblasts. This paradigm reveals fundamental mechanisms by which vesicular communication between carcinoma cells and stromal cells can promote cancer progression in the tumor microenvironment.

Cytokines Stimulate the Release of Microvesicles from Myeloid Cells Independently from the P2X7 Receptor/Acid Sphingomyelinase Pathway

Microvesicles (MVs) are membrane particles of 200–500 nm released by all cell types constitutively. MVs of myeloid origin are found increased in the cerebrospinal fluid (CSF) of patients suffering from neuroinflammatory disorders, although the factors triggering their production have never been defined. Here, we report that both pro- and anti-inflammatory cytokines, specifically interferon-γ and interleukin-4, are equally able to stimulate the production of MVs from microglia cells and monocytes. Additionally, we found this process to be independent from the best characterized molecular pathway so far described for membrane shedding, which is centered on the purinergic receptor P2X7, whose activation by high concentrations of extracellular ATP (exATP) results in membrane blebbing operated by the secreted enzyme acid sphingomyelinase (ASMase). Moreover, a potent inhibitor of ASMase, injected in a mouse model of multiple sclerosis, failed to reduce the number of MVs in their CSF. This suggests that cytokines, rather than exATP, may exert a long-term control of MV production in the context of chronic inflammation, where both pro- and anti-inflammatory factors play coordinated roles.

Circulating exosomes in obstructive sleep apnea as phenotypic biomarkers and mechanistic messengers of end-organ morbidity

Obstructive sleep apnea (OSA), the most severe form of sleep disordered breathing, is characterized by intermittent hypoxia during sleep (IH), sleep fragmentation, and episodic hypercapnia. OSA is associated with increased risk for morbidity and mortality affecting cardiovascular, metabolic, and neurocognitive systems, and more recently with non-alcoholic fatty liver disease (NAFLD) and cancer-related deaths. Substantial variability in OSA outcomes suggests that genetically-determined and environmental and lifestyle factors affect the phenotypic susceptibility to OSA. Furthermore, OSA and obesity often co-exist and manifest activation of shared molecular end-organ injury mechanisms that if properly identified may represent potential therapeutic targets. A challenge in the development of non-invasive diagnostic assays in body fluids is the ability to identify clinically relevant biomarkers. Circulating extracellular vesicles (EVs) include a heterogeneous population of vesicular structures including exosomes, prostasomes, microvesicles (MVs), ectosomes and oncosomes, and are classified based on their size, shape and membrane surface composition. Of these, exosomes (30-100nm) are very small membrane vesicles derived from multi-vesicular bodies or from the plasma membrane and play important roles in mediating cell-cell communication via cargo that includes lipids, proteins, mRNAs, miRNAs and DNA. We have recently identified a unique cluster of exosomal miRNAs in both humans and rodents exposed to intermittent hypoxia as well as in patients with OSA with divergent morbid phenotypes. Here we summarize such recent findings, and will focus on exosomal miRNAs in both adult and children which mediate intercellular communication relevant to OSA and endothelial dysfunction, and their potential value as diagnostic and prognostic biomarkers.

Exosomes: From Garbage Bins to Promising Therapeutic Targets

Intercellular communication via cell-released vesicles is a very important process for both normal and tumor cells. Cell communication may involve exosomes, small vesicles of endocytic origin that are released by all types of cells and are found in abundance in body fluids, including blood, saliva, urine, and breast milk. Exosomes have been shown to carry lipids, proteins, mRNAs, non-coding RNAs, and even DNA out of cells. They are more than simply molecular garbage bins, however, in that the molecules they carry can be taken up by other cells. Thus, exosomes transfer biological information to neighboring cells and through this cell-to-cell communication are involved not only in physiological functions such as cell-to-cell communication, but also in the pathogenesis of some diseases, including tumors and neurodegenerative conditions. Our increasing understanding of why cells release exosomes and their role in intercellular communication has revealed the very complex and sophisticated contribution of exosomes to health and disease. The aim of this review is to reveal the emerging roles of exosomes in normal and pathological conditions and describe the controversial biological role of exosomes, as it is now understood, in carcinogenesis. We also summarize what is known about exosome biogenesis, composition, functions, and pathways and discuss the potential clinical applications of exosomes, especially as biomarkers and novel therapeutic agents.

Microvesicles secreted from equine amniotic-derived cells and their potential role in reducing inflammation in endometrial cells in an in-vitro model

Background

It is known that a paracrine mechanism exists between mesenchymal stem cells and target cells. This process may involve microvesicles (MVs) as an integral component of cell-to-cell communication.

Methods

In this context, this study aims to understand the efficacy of MVs in in-vitro endometrial stressed cells in view of potential healing in in-vivo studies. For this purpose, the presence and type of MVs secreted by amniotic mesenchymal stem cells (AMCs) were investigated and the response of endometrial cells to MVs was studied using a dose-response curve at different concentrations and times. Moreover, the ability of MVs to counteract the in vitro stress in endometrial cells induced by lipopolysaccharide was studied by measuring the rate of apoptosis and cell proliferation, the expression of some pro-inflammatory genes such as tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin 1β (IL-1β), and metalloproteinases (MMP) 1 and 13, and the release of some pro- or anti-inflammatory cytokines.

Results

MVs secreted by the AMCs ranged in size from 100 to 200 nm. The incorporation of MVs was gradual over time and peaked at 72 h. MVs reduced the apoptosis rate, increased cell proliferation values, downregulated pro-inflammatory gene expression, and decreased the secretion of pro-inflammatory cytokines.

Conclusion

Our data suggest that some microRNAs could contribute to counteracting in-vivo inflammation of endometrial tissue.

Microvesicles shed from fibroblasts act as metalloproteinase carriers in a 3-D collagen matrix

This study shows that fibroblasts migrating into a collagen matrix release numerous microvesicles into the surrounding medium. By spreading in regions of the matrix far distant from cells of origin, microvesicles carry metalloproteinase 9 (MMP-9) to act upon the collagen fibrils. As a result, the collagen matrix is gradually transformed from a laminar to a fibrillar type of architecture. As shown by western blots and gelatin zymography, MMP-9 is secreted as a 92 kDa precursor and activated upon release of 82 kDa product into the culture medium. Activation is more efficient under three-dimensional than in two-dimensional culturing conditions. While MMP-9 labeling is associated with intraluminal vesicles clustered inside the microvesicles, the microvesicle's integrin β1 marker is bound to the outer membrane. The intraluminal vesicles are recruited from the cortical cytoplasm and eventually released following uploading inside the microvesicle. Here, we propose that fusion of the intraluminal vesicles with the outer microvesicle's membrane could work as a mechanism controlling the extent to which MMP-9 is first activated and then released extracellularly.

Exosomes as the source of biomarkers of metabolic diseases

Exosomes are extracellular vesicles that contain molecules that regulate the metabolic functions of adjacent or remote cells. Recent in vitro, in vivo and clinical studies support the hypothesis that exosomes released from various cell types play roles in the progression of metabolic disorders including type 2 diabetes. Based on this concept and advances in other diseases, the proteins, mRNA, microRNA and lipids in exosomes isolated from biological fluids have been proposed as biomarkers in metabolic disorders. However, several problems with the development of clinically applicable biomarkers have not been resolved. In this review, the biologic functions of exosomes are briefly introduced, and we discuss the technical and practical pros and cons of different methods of exosome isolation for the identification of exosomal biomarkers of metabolic disorders. Standardization of preanalytical variables and isolation of high-purity exosomes from fully characterized biological fluids will be necessary for the identification of useful exosomal biomarkers that can provide insights into the pathogenic mechanisms of complications of metabolic syndrome and of whole-body metabolism.

Microvesicles as Vehicles for Tissue Regeneration: Changing of the Guards

PURPOSE OF REVIEW

Microvesicles (MVs) have been recognised as mediators of stem cell function, enabling and guiding their regenerative effects.

RECENT FINDINGS

MVs constitute one unique size class of extracellular vesicles (EVs) directly shed from the cell plasma membrane. They facilitate cell-to-cell communication via intercellular transfer of proteins, mRNA and microRNA (miRNA). MVs derived from stem cells, or stem cell regulatory cell types, have proven roles in tissue regeneration and repair processes. Their role in the maintenance of healthy tissue function throughout the life course and thus in age related health span remains to be elucidated.

SUMMARY

Understanding the biogenesis and mechanisms of action of MVs may enable the development of cell-free therapeutics capable of assisting in tissue maintenance and repair for a variety of age-related degenerative diseases. This review critically evaluates recent work published in this area and highlights important new findings demonstrating the use of MVs in tissue regeneration.

Targeting annexin A2 reduces tumorigenesis and therapeutic resistance of nasopharyngeal carcinoma

The expression of annexin A2 (ANXA2) in nasopharyngeal carcinoma (NPC) cells induces the immunosuppressive response in dendritic cells; however, the oncogenic effect and clinical significance of ANXA2 have not been fully investigated in NPC cells. Immunohistochemical staining for ANXA2 was performed in 61 patients and the association with clinicopathological status was determined. Short hairpin (sh)RNA knockdown of ANXA2 was used to examine cellular effects of ANXA2, by investigating alterations in cell proliferation, migration, invasion, adhesion, tube-formation assay, and chemo- and radiosensitivity assays were performed. RT-qPCR, Western blotting, and immunofluorescence were applied to determine molecular expression levels. Clinical association studies showed that the expression of ANXA2 was significantly correlated with metastasis (p = 0.0326) and poor survival (p = 0.0256). Silencing of ANXA2 suppressed the abilities of cell proliferation, adhesion, migration, invasion, and vascular formation in NPC cell. ANXA2 up-regulated epithelial-mesenchymal transition associated signal proteins. Moreover, ANXA2 reduced sensitivities to irradiation and chemotherapeutic drugs. These results define ANXA2 as a novel prognostic factor for malignant processes, and it can serve as a molecular target of therapeutic interventions for NPC.

Extracellular vesicles are transferred from melanocytes to keratinocytes after UVA irradiation

Ultraviolet (UV) irradiation induces skin pigmentation, which relies on the intercellular crosstalk of melanin between melanocytes to keratinocytes. However, studying the separate effects of UVA and UVB irradiation reveals differences in cellular response. Herein, we show an immediate shedding of extracellular vesicles (EVs) from the plasma membrane when exposing human melanocytes to UVA, but not UVB. The EV-shedding is preceded by UVA-induced plasma membrane damage, which is rapidly repaired by Ca(2+)-dependent lysosomal exocytosis. Using co-cultures of melanocytes and keratinocytes, we show that EVs are preferably endocytosed by keratinocytes. Importantly, EV-formation is prevented by the inhibition of exocytosis and increased lysosomal pH but is not affected by actin and microtubule inhibitors. Melanosome transfer from melanocytes to keratinocytes is equally stimulated by UVA and UVB and depends on a functional cytoskeleton. In conclusion, we show a novel cell response after UVA irradiation, resulting in transfer of lysosome-derived EVs from melanocytes to keratinocytes.

Extracellular Vesicles in Physiology, Pathology, and Therapy of the Immune and Central Nervous System, with Focus on Extracellular Vesicles Derived from Mesenchymal Stem Cells as Therapeutic Tools

Extracellular vesicles (EVs) are membrane-surrounded structures released by most cell types. They are characterized by a specific set of proteins, lipids and nucleic acids. EVs have been recognized as potent vehicles of intercellular communication to transmit biological signals between cells. In addition, pathophysiological roles of EVs in conditions like cancer, infectious diseases and neurodegenerative disorders are well established. In recent years focus has been shifted on therapeutic use of stem cell derived-EVs. Use of stem cell derived-EVs present distinct advantage over the whole stem cells as EVs do not replicate and after intravenous administration, they are less likely to trap inside the lungs. From the therapeutic perspective, the most promising cellular sources of EVs are mesenchymal stem cells (MSCs), which are easy to obtain and maintain. Therapeutic activity of MSCs has been shown in numerous animal models and the beneficial paracrine effect of MSCs may be mediated by EVs. The various components of MSC derived-EVs such as proteins, lipids, and RNA might play a specific therapeutic role. In this review, we characterize the role of EVs in immune and central nervous system (CNS); present evidences for defective signaling of these vesicles in neurodegeneration and therapeutic role of EVs in CNS.

Membrane traffic during axon development

Brain formation requires the establishment of complex neural circuits between a diverse array of neuronal subtypes in an intricate and ever changing microenvironment and yet with a large degree of specificity and reproducibility. In the last three decades, mounting evidence has established that neuronal development relies on the coordinated regulation of gene expression, cytoskeletal dynamics, and membrane trafficking. Membrane trafficking has been considered important in that it brings new membrane and proteins to the plasma membrane of developing neurons and because it also generates and maintains the polarized distribution of proteins into neuronal subdomains. More recently, accumulating evidence suggests that membrane trafficking may have an even more active role during development by regulating the distribution and degree of activation of a wide variety of proteins located in plasma membrane subdomains and endosomes. In this article the evidence supporting the different roles of membrane trafficking during axonal development, particularly focusing on the role of SNAREs and Rabs was reviewed. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 76: 1185-1200, 2016.

Focus on Extracellular Vesicles: Introducing the Next Small Big Thing

Intercellular communication was long thought to be regulated exclusively through direct contact between cells or via release of soluble molecules that transmit the signal by binding to a suitable receptor on the target cell, and/or via uptake into that cell. With the discovery of small secreted vesicular structures that contain complex cargo, both in their lumen and the lipid membrane that surrounds them, a new frontier of signal transduction was discovered. These “extracellular vesicles” (EV) were initially thought to be garbage bags through which the cell ejected its waste. Whilst this is a major function of one type of EV, i.e., apoptotic bodies, many EVs have intricate functions in intercellular communication and compound exchange; although their physiological roles are still ill-defined. Additionally, it is now becoming increasingly clear that EVs mediate disease progression and therefore studying EVs has ignited significant interests among researchers from various fields of life sciences. Consequently, the research effort into the pathogenic roles of EVs is significantly higher even though their protective roles are not well established. The “Focus on extracellular vesicles” series of reviews highlights the current state of the art regarding various topics in EV research, whilst this review serves as an introductory overview of EVs, their biogenesis and molecular composition.

Myeloid Extracellular Vesicles: Messengers from the Demented Brain

Blood-borne monocyte derived cells play a pivotal, initially unrecognized, role in most central nervous system disorders, including diseases initially classified as purely neurodegenerative (i.e., Alzheimer’s disease, Parkinson’s disease, and ALS). Their trafficking to the brain and spinal cord has been extensively studied in classical neuroinflammatory disorders such as multiple sclerosis. Central nervous system resident myeloid cells, namely microglia and perivascular macrophages, also are in the spotlight of investigations on neurological disorders. Myeloid cells, such as infiltrating macrophages and microglia, have been described as having both protective and destructive features in neurological disorders, thus identification of their functional phenotype during disease evolution would be of paramount importance. Extracellular vesicles, namely exosomes and shed vesicles, are released by virtually any cell type and can be detected and identified in terms of cell origin in biological fluids. They therefore constitute an ideal tool to access information on cells residing in an inaccessible site such as the brain. We will review here available information on extracellular vesicles detection in neurological disorders with special emphasis on neurodegenerative diseases.

Biogenesis and Functions of Exosomes and Extracellular Vesicles

Research on extracellular vesicles (EVs) is a new and emerging field that is rapidly growing. Many features of these structures still need to be described and discovered. This concerns their biogenesis, their release and cellular entrance mechanisms, as well as their functions, particularly in vivo. Hence our knowledge on EV is constantly evolving and sometimes changing. In our review we summarize the most important facts of our current knowledge about extracellular vesicles and described some of the assumed functions in the context of cancer and HIV infection.

Isolation of exosomes by differential centrifugation: Theoretical analysis of a commonly used protocol

Exosomes, small (40-100 nm) extracellular membranous vesicles, attract enormous research interest because they are carriers of disease markers and a prospective delivery system for therapeutic agents. Differential centrifugation, the prevalent method of exosome isolation, frequently produces dissimilar and improper results because of the faulty practice of using a common centrifugation protocol with different rotors. Moreover, as recommended by suppliers, adjusting the centrifugation duration according to rotor K-factors does not work for "fixed-angle" rotors. For both types of rotors--"swinging bucket" and "fixed-angle"--we express the theoretically expected proportion of pelleted vesicles of a given size and the "cut-off" size of completely sedimented vesicles as dependent on the centrifugation force and duration and the sedimentation path-lengths. The proper centrifugation conditions can be selected using relatively simple theoretical estimates of the "cut-off" sizes of vesicles. Experimental verification on exosomes isolated from HT29 cell culture supernatant confirmed the main theoretical statements. Measured by the nanoparticle tracking analysis (NTA) technique, the concentration and size distribution of the vesicles after centrifugation agree with those theoretically expected. To simplify this "cut-off"-size-based adjustment of centrifugation protocol for any rotor, we developed a web-calculator.

Extracellular Vesicles from Caveolin-Enriched Microdomains Regulate Hyaluronan-Mediated Sustained Vascular Integrity

Defects in vascular integrity are an initiating factor in several disease processes. We have previously reported that high molecular weight hyaluronan (HMW-HA), a major glycosaminoglycan in the body, promotes rapid signal transduction in human pulmonary microvascular endothelial cells (HPMVEC) leading to barrier enhancement. In contrast, low molecular weight hyaluronan (LMW-HA), produced in disease states by hyaluronidases and reactive oxygen species (ROS), induces HPMVEC barrier disruption. However, the mechanism(s) of sustained barrier regulation by HA are poorly defined. Our results indicate that long-term (6–24 hours) exposure of HMW-HA induced release of a novel type of extracellular vesicle from HLMVEC called enlargeosomes (characterized by AHNAK expression) while LMW-HA long-term exposure promoted release of exosomes (characterized by CD9, CD63, and CD81 expression). These effects were blocked by inhibiting caveolin-enriched microdomain (CEM) formation. Further, inhibiting enlargeosome release by annexin II siRNA attenuated the sustained barrier enhancing effects of HMW-HA. Finally, exposure of isolated enlargeosomes to HPMVEC monolayers generated barrier enhancement while exosomes led to barrier disruption. Taken together, these results suggest that differential release of extracellular vesicles from CEM modulate the sustained HPMVEC barrier regulation by HMW-HA and LMW-HA. HMW-HA-induced specialized enlargeosomes can be a potential therapeutic strategy for diseases involving impaired vascular integrity.

Understanding the biosynthesis of platelets-derived extracellular vesicles

Platelet-derived extracellular vesicles (PEVs) are described as sub-cellular vesicles released into circulation upon platelets shear stress, activation, injury, or apoptosis. They are considered as universal biomarkers in a wide range of physiological and pathological processes. They are of tremendous significance for the prediction, diagnosis, and observation of the therapeutic success of many diseases. Understanding their biosynthesis and therefore functional properties would contribute to a better understanding of the pathological mechanisms leading to various diseases in which their levels are raised and they are implicated. The review takes a critical look at the historical background of PEVs, their structural components, the mechanism of their formation, physiological, and exogenous stimuli inducing their release and their detection. It concludes by highlighting on the importance of undertaking in-depth studies into PEVs biosynthesis and subsequently gaining a better understanding of their biological role in general.

Cell-derived vesicles for drug therapy and diagnostics: opportunities and challenges

Extracellular vesicles are small lipid-based membrane-bound entities shed by cells under both physiological and pathological conditions. Their discovery as intercellular communicators through transfer of nucleic acid- and protein-based cargos between cells locally and at distance in a highly specific manner has created recent excitement. The information they transport and their composition may vary depending on the cell of origin as well as the eliciting stimulus. Such sensitive changes in vesicle characteristics hold significant promise for the improved diagnosis of pathological conditions, including infections and neoplastic lesions in a minimally invasive way. Similarly, these cell-derived vesicles exhibit promising characteristics that could enhance drug targeting efficiencies. Recent developments in the field have aimed at studying EVs as novel drug carriers due to their natural composition, biological function and selective cell interaction. In this review, we discuss new research avenues in diagnostics and drug therapy based on extracellular vesicles. We show how cell-derived vesicles can be harvested and engineered to meet application-specific design requirements. We finally discuss potential risks encountered when translating extracellular vesicle based approaches into (pre)clinical applications.

Visualization and tracking of tumour extracellular vesicle delivery and RNA translation using multiplexed reporters

Accurate spatiotemporal assessment of extracellular vesicle (EV) delivery and cargo RNA translation requires specific and robust live-cell imaging technologies. Here we engineer optical reporters to label multiple EV populations for visualization and tracking of tumour EV release, uptake and exchange between cell populations both in culture and in vivo. Enhanced green fluorescence protein (EGFP) and tandem dimer Tomato (tdTomato) were fused at NH₂-termini with a palmitoylation signal (PalmGFP, PalmtdTomato) for EV membrane labelling. To monitor EV-RNA cargo, transcripts encoding PalmtdTomato were tagged with MS2 RNA binding sequences and detected by co-expression of bacteriophage MS2 coat protein fused with EGFP. By multiplexing fluorescent and bioluminescent EV membrane reporters, we reveal the rapid dynamics of both EV uptake and translation of EV-delivered cargo mRNAs in cancer cells that occurred within 1-hour post-horizontal transfer between cells. These studies confirm that EV-mediated communication is dynamic and multidirectional between cells with delivery of functional mRNA.

Extracellular vesicles (EVs) act as a conduit for intercellular communication through the exchange of cellular materials without direct cell-to-cell contacts. Here the authors develop a multiplexed reporter system that allows monitoring of EV exchange, cargo delivery and protein translation between different cell populations.

Exosomes in bodily fluids are a highly stable resource of disease biomarkers

Biomarkers are measurable indicators of a biological state. As our understanding of diseases meliorates, it is generally accepted that early diagnosis renders the best chance to cure a disease. In the context of proteomics, the discovery phase of identifying bonafide biomarkers and the ensuing validation phase involving large cohort of patient samples are impeded by the complexity of bodily fluid samples. High abundant proteins found in blood plasma make it difficult for the detection of low abundant proteins that may be potential biomarkers. Extracellular vesicles (EVs) have reignited interest in the field of biomarker discovery. EVs contain a tissue-type signature wherein a rich cargo of proteins and RNA are selectively packaged. In addition, as EVs are membranous structures, the luminal contents are protected from degradation by extracellular proteases and are highly stable in storage conditions. Interestingly, an appealing feature of EV-based biomarker analysis is the significant reduction in the sample complexity compared to whole bodily fluids. With these prescribed attributes, which are the rate-limiting factors of traditional biomarker analysis, there is immense potential for the use of EVs for biomarker detection in clinical settings. This review will discuss the current issues with biomarker analysis and the potential use of EVs as reservoirs of disease biomarkers.

Ectosomes and exosomes: shedding the confusion between extracellular vesicles

Long- and short-distance communication can take multiple forms. Among them are exosomes and ectosomes, extracellular vesicles (EVs) released from the cell to deliver signals to target cells. While most of our understanding of how these vesicles are assembled and work comes from mechanistic studies performed on exosomes, recent studies have begun to shift their focus to ectosomes. Unlike exosomes, which are released on the exocytosis of multivesicular bodies (MVBs), ectosomes are ubiquitous vesicles assembled at and released from the plasma membrane. Here we review the similarities and differences between these two classes of vesicle, suggesting that, despite their considerable differences, the functions of ectosomes may be largely analogous to those of exosomes. Both vesicles appear to be promising targets in the diagnosis and therapy of diseases, especially cancer.

Exosomes in cancer development, metastasis, and drug resistance: a comprehensive review

Trafficking of biological material across membranes is an evolutionary conserved mechanism and is part of any normal cell homeostasis. Such transport is composed of active, passive, export through microparticles, and vesicular transport (exosomes) that collectively maintain proper compartmentalization of important micro- and macromolecules. In pathological states, such as cancer, aberrant activity of the export machinery results in expulsion of a number of key proteins and microRNAs resulting in their misexpression. Exosome-mediated expulsion of intracellular drugs could be another barrier in the proper action of most of the commonly used therapeutics, targeted agents, and their intracellular metabolites. Over the last decade, a number of studies have revealed that exosomes cross-talk and/or influence major tumor-related pathways, such as hypoxia-driven epithelial-to-mesenchymal transition, cancer stemness, angiogenesis, and metastasis involving many cell types within the tumor microenvironment. Emerging evidence suggests that exosome-secreted proteins can also propel fibroblast growth, resulting in desmoplastic reaction, a major barrier in effective cancer drug delivery. This comprehensive review highlights the advancements in the understanding of the biology of exosomes secretions and the consequence on cancer drug resistance. We propose that the successful combination of cancer treatments to tackle exosome-mediated drug resistance requires an interdisciplinary understanding of these cellular exclusion mechanisms, and how secreted biomolecules are involved in cellular cross-talk within the tumor microenvironment.