Colorimetric nanoplasmonic assay to determine purity and titrate extracellular vesicles

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

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

Advances in Extracellular Vesicle Research Over the Past Decade: Source and Isolation Method are Connected with Cargo and Function

The evolution of extracellular vesicle (EV) research has introduced nanotechnology into biomedical cell communication science while recognizing what is formerly considered cell "dust" as constituting an entirely new universe of cell signaling particles. To display the global EV research landscape, a systematic review of 20 364 original research articles selected from all 40 684 EV-related records identified in PubMed 2013-2022 is performed. Machine-learning is used to categorize the high-dimensional data and further dissected significant associations between EV source, isolation method, cargo, and function. Unexpected correlations between these four categories indicate prevalent experimental strategies based on cargo connectivity with function of interest being associated with certain EV sources or isolation strategies. Conceptually relevant association of size-based EV isolation with protein cargo and uptake function will guide strategic conclusions enhancing future EV research and product development. Based on this study, an open-source database is built to facilitate further analysis with conventional or AI tools to identify additional causative associations of interest.

Controlling plasmonic suprastructures through self-assembly of gold nanoparticles with hybrid copolymer-lipid vesicles

Hybrid lipid membranes incorporating amphiphilic copolymers have gained significant attention due to their potential applications in various fields, including drug delivery and sensing. By combining the properties of copolymers and lipid membranes, such as enhanced chemical tunability and stability, environmental responsiveness, and multidomain nature, novel membrane architectures have been proposed. In this study, we investigated the potentialities of hybrid membranes made of two distinct components: the rigid fully saturated phospholipid 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and the soft copolymer poly(butadiene-b-ethyleneoxide) (PBD-b-PEO). The objective was to explore the interaction of citrate-coated gold nanoparticles (AuNPs) and the hybrid membrane, aiming at constructing AuNPs-hybrid vesicles suprastructures with controlled and adjustable plasmonic properties. A series of experimental techniques were employed to investigate hybrid free-standing and supported membranes. The results revealed that the incorporation of the copolymer into the lipid membrane promotes AuNPs clustering, demonstrating a distinctive aggregative phenomenon of citrate-coated AuNPs on multidomain membranes. Importantly, we show that the size and morphology of AuNPs clusters can be precisely controlled in non-homogeneous membranes, enabling the formation of hybrid suprastructures with controlled patch properties. These results highlight the potential of lipid-copolymer hybrid membranes for designing functional materials with tailored plasmonic properties, with potential applications in nanomedicine and sensing.

Small extracellular vesicles derived from human adipose-derived mesenchymal stromal cells cultured in a new chemically-defined contaminate-free media exhibit enhanced biological and therapeutic effects on human chondrocytes in vitro and in a mouse osteoarthritis model

Human small extracellular vesicles (sEVs) derived from adipose-derived mesenchymal stromal cells (ASC) have been reported to suppress the progression of osteoarthritis (OA) in animal studies and subsequently, translation of this potential to assess their clinical efficacy is anticipated. However, fabrication protocols for sEVs to eliminate potential contamination by culture medium-derived components need to be established prior to their clinical use. The purpose of the present studies was to elucidate the influence of medium-derived contaminants on the biological effects of sEVs, and to establish isolation methods for sEVs using a new clinical grade chemically-defined media (CDM). The quantity and purity of ASC-derived sEVs cultured in four different CDMs (CDM1, 2, 3 and 4) were evaluated. The concentrates of the four media incubated without cells were used as the background (BG) control for each set of sEVs. The biological effect of sEVs fabricated in the four different CDMs on normal human articular chondrocytes (hACs) were evaluated in vitro using a variety of methodological assessments. Finally, the sEVs with the highest purity were tested for their ability to suppress the progression of knee OA mouse model. Analysis of the BG controls revealed that CDM1-3 contained detectable particles, while there was no visible contamination of culture media-derived components detected with CDM4. Accordingly, the sEVs fabricated with CDM4 (CDM4-sEVs) exhibited the highest purity and yield. Notably, the CDM4-sEVs were the most efficient in promoting the cellular proliferation, migration, chondrogenic differentiation, and anti-apoptotic activity of hACs. Furthermore, CDM4-sEVs significantly suppressed the osteochondral degeneration in vivo model. Small EVs derived from ASCs cultured in a CDM without detectable contaminants demonstrated enhanced biological effects on hACs and the progression of OA. Thus, sEVs isolated with CDM4 most optimally meet the requirements of efficacy and safety for assessment in their future clinical applications.

Technological aspects of manufacturing and analytical control of biological nanoparticles

Extracellular vesicles (EVs) are cell-derived biological nanoparticles that gained great interest for drug delivery. EVs have numerous advantages compared to synthetic nanoparticles, such as ideal biocompatibility, safety, ability to cross biological barriers and surface modification via genetic or chemical methods. On the other hand, the translation and the study of these carriers resulted difficult, mostly because of significant issues in up-scaling, synthesis and impractical methods of quality control. However, current manufacturing advances enable EV packaging with any therapeutic cargo, including DNA, RNA (for RNA vaccines and RNA therapeutics), proteins, peptides, RNA-protein complexes (including gene-editing complexes) and small molecules drugs. To date, an array of new and upgraded technologies have been introduced, substantially improving EV production, isolation, characterization and standardization. The used-to-be "gold standards" of EV manufacturing are now outdated, and the state-of-art requires extensive revision. This review re-evaluates the pipeline for EV industrial production and provides a critical overview of the modern technologies required for their synthesis and characterization.

Viral Vectors, Exosomes, and Vexosomes: Potential Armamentarium for Delivering CRISPR/Cas to Cancer Cells

The underlying cause of cancer is genetic disruption, so gene editing technologies, particularly CRISPR/Cas systems can be used to go against cancer. The field of gene therapy has undergone many transitions over its 40-year history. Despite its many successes, it has also suffered many failures in the battle against malignancies, causing really adverse effects instead of therapeutic outcomes. At the tip of this double-edged sword are viral and non-viral-based vectors, which have profoundly transformed the way scientists and clinicians develop therapeutic platforms. Viruses such as lentivirus, adenovirus, and adeno-associated viruses are the most common viral vectors used for delivering the CRISPR/Cas system into human cells. In addition, among non-viral vectors, exosomes, especially tumor-derived exosomes (TDEs), have proven to be quite effective at delivering this gene editing tool. The combined use of viral vectors and exosomes, called vexosomes, seems to be a solution to overcoming the obstacles of both delivery systems.

Probing the coverage of nanoparticles by biomimetic membranes through nanoplasmonics

Although promising for biomedicine, the clinical translation of inorganic nanoparticles (NPs) is limited by low biocompatibility and stability in biological fluids. A common strategy to circumvent this drawback consists in disguising the active inorganic core with a lipid bilayer coating, reminiscent of the structure of the cell membrane to redefine the chemical and biological identity of NPs. While recent reports introduced membrane-coating procedures for NPs, a robust and accessible method to quantify the integrity of the bilayer coverage is not yet available. To fill this gap, we prepared SiO₂ nanoparticles (SiO₂NPs) with different membrane coverage degrees and monitored their interaction with AuNPs by combining microscopic, scattering, and optical techniques. The membrane-coating on SiO₂NPs induces spontaneous clustering of AuNPs, whose extent depends on the coating integrity. Remarkably, we discovered a linear correlation between the membrane coverage and a spectral descriptor for the AuNPs' plasmonic resonance, spanning a wide range of coating yields. These results provide a fast and cost-effective assay to monitor the compatibilization of NPs with biological environments, essential for bench tests and scale-up. In addition, we introduce a robust and scalable method to prepare SiO₂NPs/AuNPs hybrids through spontaneous self-assembly, with a high-fidelity structural control mediated by a lipid bilayer.

Biochemical Characterization of Human Salivary Extracellular Vesicles as a Valuable Source of Biomarkers

Extracellular vesicles (EVs) are natural nanoparticles secreted under physiological and pathological conditions. Thanks to their diagnostic potential, EVs are increasingly being studied as biomarkers of a variety of diseases, including neurological disorders. To date, most studies on EV biomarkers use blood as the source, despite different disadvantages that may cause an impure isolation of the EVs. In the present article, we propose the use of saliva as a valuable source of EVs that could be studied as biomarkers in an easily accessible biofluid. Using a comparable protocol for the isolation of EVs from both liquid biopsies, salivary EVs showed greater purity in terms of co-isolates (evaluated by nanoparticle tracking analysis and Conan test). In addition, Raman spectroscopy was used for the identification of the overall biochemical composition of EVs coming from the two different biofluids. Even considering the limited amount of EVs that can be isolated from saliva, the use of Raman spectroscopy was not hampered, and it was able to provide a comprehensive characterization of EVs in a high throughput and repeatable manner. Raman spectroscopy can thus represent a turning point in the application of salivary EVs in clinics, taking advantage of the simple method of collection of the liquid biopsy and of the quick, sensitive and label-free biophotonics-based approach.

Practical Considerations for Translating Mesenchymal Stromal Cell-Derived Extracellular Vesicles from Bench to Bed

Extracellular vesicles (EVs) derived from mesenchymal stromal cells (MSCs) have shown potential for the treatment of tendon and ligament injuries. This approach can eliminate the need to transplant live cells to the human body, thereby reducing issues related to the maintenance of cell viability and stability and potential erroneous differentiation of transplanted cells to bone or tumor. Despite these advantages, there are practical issues that need to be considered for successful clinical application of MSC-EV-based products in the treatment of tendon and ligament injuries. This review aims to discuss the general and tissue-specific considerations for manufacturing MSC-EVs for clinical translation. Specifically, we will discuss Good Manufacturing Practice (GMP)-compliant manufacturing and quality control (parent cell source, culture conditions, concentration method, quantity, identity, purity and impurities, sterility, potency, reproducibility, storage and formulation), as well as safety and efficacy issues. Special considerations for applying MSC-EVs, such as their compatibility with arthroscopy for the treatment of tendon and ligament injuries, are also highlighted.

Human Microglia Extracellular Vesicles Derived from Different Microglia Cell Lines: Similarities and Differences

Microglial cells are a component of the innate immune system in the brain that support cell-to-cell communication via secreted molecules and extracellular vesicles (EVs). EVs can be divided into two major populations: large (LEVs) and small (SEVs) EVs, carrying different mediators, such as proteins, lipids, and miRNAs. The microglia EVs cargo crucially reflects the status of parental cells and can lead to both beneficial and detrimental effects in many physiopathological states. Herein, a workflow for the extraction and characterization of SEVs and LEVs from human C20 and HMC3 microglia cell lines derived, respectively, from adult and embryonic microglia is reported. EVs were gathered from the culture media of the two cell lines by sequential ultracentrifugation steps and their biochemical and biophysical properties were analyzed by Western blot, transmission electron microscopy, and dynamic light scattering. Although the C20- and HMC3-derived EVs shared several common features, C20-derived EVs were slightly lower in number and more polydispersed. Interestingly, C20- but not HMC3-SEVs were able to interfere with the proliferation of U87 glioblastoma cells. This correlated with the different relative levels of eight miRNAs involved in neuroinflammation and tumor progression in the C20- and HMC3-derived EVs, which in turn reflected a different basal activation state of the two cell types. Our data fill a gap in the community of microglia EVs, in which the preparations from human cells have been poorly characterized so far. Furthermore, these results shed light on both the differences and similarities of EVs extracted from different human microglia cell models, underlining the need to better characterize the features and biological effects of EVs for therein useful and correct application.

SARS-CoV-2 Detection using Colorimetric Plasmonic Sensors: A Proof-of-Concept Computational Study

Traditional molecular techniques for SARS-CoV-2 viral detection are time-consuming and can exhibit a high probability of false negatives. In this work, we present a computational study of SARS-CoV-2 detection using plasmonic gold nanoparticles. The resonance wavelength of a SARS-CoV-2 virus was recently estimated to be in the near-infrared region. By engineering gold nanospheres to specifically bind with the outer surface of the SARS-CoV-2 virus, the resonance frequency can be shifted to the visible range (380 nm - 700 nm). Moreover, we show that broadband absorption will emerge in the visible spectrum when the virus is partially covered with gold nanoparticles at a specific coverage percentage. This broadband absorption can be used to guide the development of an efficient and accurate colorimetric plasmon sensor for COVID-19 detection. Our observation also suggests that this technique is unaffected by the number of protein spikes present on the virus outer surface, hence can pave a potential path for a label-free COVID-19 diagnostic tool independent of the number of protein spikes.

Salting-Out Approach Is Worthy of Comparison with Ultracentrifugation for Extracellular Vesicle Isolation from Tumor and Healthy Models

The role of extracellular vesicles (EVs) has been completely re-evaluated in the recent decades, and EVs are currently considered to be among the main players in intercellular communication. Beyond their functional aspects, there is strong interest in the development of faster and less expensive isolation protocols that are as reliable for post-isolation characterisations as already-established methods. Therefore, the identification of easy and accessible EV isolation techniques with a low price/performance ratio is of paramount importance. We isolated EVs from a wide spectrum of samples of biological and clinical interest by choosing two isolation techniques, based on their wide use and affordability: ultracentrifugation and salting-out. We collected EVs from human cancer and healthy cell culture media, yeast, bacteria and Drosophila culture media and human fluids (plasma, urine and saliva). The size distribution and concentration of EVs were measured by nanoparticle tracking analysis and dynamic light scattering, and protein depletion was measured by a colorimetric nanoplasmonic assay. Finally, the EVs were characterised by flow cytometry. Our results showed that the salting-out method had a good efficiency in EV separation and was more efficient in protein depletion than ultracentrifugation. Thus, salting-out may represent a good alternative to ultracentrifugation.

Progress in Nanomaterials-Based Optical and Electrochemical Methods for the Assays of Exosomes

Exosomes with diameters of 30-150 nm are small membrane-bound vesicles secreted by a variety of cells. They play an important role in many biological processes, such as tumor-related immune response and intercellular signal transduction. Exosomes have been considered as emerging and noninvasive biomarkers for cancer diagnosis. Recently, a large number of optical and electrochemical biosensors have been proposed for sensitive detection of exosomes. To meet the increasing demands for ultrasensitive detection, nanomaterials have been integrated with various techniques as powerful components. Because of their intrinsic merits of biological compatibility, excellent physicochemical features and unique catalytic ability, nanomaterials have significantly improved the analytical performances of exosome biosensors. In this review, we summarized the recent progress in nanomaterials-based biosensors for the detection of cancer-derived exosomes, including fluorescence, colorimetry, surface plasmon resonance spectroscopy, surface enhanced Raman scattering spectroscopy, electrochemistry, electrochemiluminescence and so on.

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

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

A plasmon-based nanoruler to probe the mechanical properties of synthetic and biogenic nanosized lipid vesicles

Nanosized lipid vesicles are ubiquitous in living systems (e.g. cellular compartments or extracellular vesicles, EVs) and in formulations for nanomedicine (e.g. liposomes for RNA vaccine formulations). The mechanical properties of such vesicles are crucial in several physicochemical and biological processes, ranging from cellular uptake to stability in aerosols. However, their accurate determination remains challenging and requires sophisticated instruments and data analysis. Here we report the first evidence that the surface plasmon resonance (SPR) of citrated gold nanoparticles (AuNPs) adsorbed on synthetic vesicles is finely sensitive to the vesicles' mechanical properties. We then leverage this finding to show that the SPR tracking provides quantitative access to the stiffness of vesicles of synthetic and natural origin, such as EVs. The demonstration of this plasmon-based "stiffness nanoruler" paves the way for developing a facile, cost-effective and high-throughput method to assay the mechanical properties of dispersions of vesicles of nanometric size and unknown composition at a collective level.

Progress in the research of nanomaterial-based exosome bioanalysis and exosome-based nanomaterials tumor therapy

Exosomes and their internal components have been proven to play critical roles in cell-cell interactions and intrinsic cellular regulations, showing promising prospects in both biomedical and clinical fields. Although conventional methods have so far been utilized to great effect, accurate bioanalysis remains a major challenge. In recent years, the fast-paced development of nanomaterials with unique physiochemical properties has led to a boom in the potential bioapplications of such materials. In particular, the application of nanomaterials in exosome bioanalysis provides a great opportunity to overcome the current challenges and limitations of conventional methods. A timely review of the research progress in this field is thus of great significance to the continued development of new methods. This review outlines the properties and potential uses of exosomes, and discusses the conventional methods currently used for their analysis. We then focus on exploring the current state of the art regarding the use of nanomaterials for the isolation, detection and even the subsequent profiling of exosomes. The main methods are based on principles including fluorescence, surface-enhanced Raman spectroscopy, colorimetry, electrochemistry, and surface plasmon resonance. Additionally, research on exosome-based nanomaterials tumor therapy is also promising from a clinical perspective, so the research progress in this branch is also summarized. Finally, we look at ways in which the field might develop in the future.

A magnetic bead-mediated selective adsorption strategy for extracellular vesicle separation and purification

Extracellular vesicles (EVs) are membrane-encapsulated particles with critical biomedical functions, including mediating intercellular communication, assisting tumor metastasis, and carrying protein and microRNA biomarkers. The downstream applications of EVs are greatly influenced by the quality of the isolated EVs. However, almost none of the separation methods can simultaneously achieve both high yield and high purity of the isolated EVs, thus making the isolation of EVs an essential challenge in EV research. Here, we developed a magnetic bead-mediated selective adsorption strategy (MagExo) for easy-to-operate EV isolation. Benefited from the presence of an adsorption window between EVs and proteins under the effect of a hydrophilic polymer, EVs tend to adsorb on the surface of magnetic beads selectively and can be separated from biological fluids with high purity by simple magnetic separation. The proposed method was used for EV isolation from plasma and cell culture media (CCM), with two times higher yield and comparable purity of the harvested EVs to that obtained by ultracentrifugation (UC). Downstream applications in proteomics analysis showed 86.6% (plasma) and 86.5% (CCM) of the analyzed proteins were matched with the ExoCarta database, which indicates MagExo indeed enriches EVs efficiently. Furthermore, we found the target RNA amount of the isolated EVs by MagExo were almost dozens and hundred times higher than the gold standard DG-UC and ultracentrifugation (UC) methods, respectively. All the results show that MagExo is a reliable, easy, and efficient approach to harvest EVs for a wide variety of downstream applications with minimized sample usage. STATEMENT OF SIGNIFICANCE: Extracellular vesicles (EVs) are presently attracting increasing interest among clinical and scientific researchers. Although the downstream applications of EVs are recognized to be greatly affected by the quality of the isolated EVs, almost none of the separation methods can simultaneously achieve high yield and high purity of the isolated EVs; this makes the isolation of EVs an essential challenge in EV research. In the present work, we proposed a simple and easy-to-operate method (MagExo) for the separation and purification of EVs based on the phenomenon that EVs can be selectively adsorbed on the surface of magnetic microspheres in the presence of a hydrophilic polymer. The performance of MagExo was comparable to or even better than that of gold standard methods and commercial kits, with two times higher yield and comparable purity of the harvested EVs to that achieved with ultracentrifugation (UC); this could meet the requirements of various EV-associated downstream applications. In addition, MagExo can be easily automated by commercial liquid workstations, thus significantly improving the isolation throughput and paving a new way in clinical diagnosis and treatment.

Colorimetric analysis of extracellular vesicle surface proteins based on controlled growth of Au aptasensors

Protein profiling of extracellular vesicles (EVs) provides important information in both clinical cancer diagnosis and relevant biological research studies. Although a variety of bioanalytical techniques have been investigated for EV characterization, limitations such as time-consuming operations, the requirement of large sample volume and demand for specialized instruments hinder their practical applications. Here, we report a simple and wash-free homogeneous colorimetric assay for sensitive detection of surface proteins on EVs. Au nanoparticles were modified with thiolated aptamers to fabricate aptasensors and incubated with EVs. Upon addition of a Au growth reagent, the solution color changed from light red to blue in the presence of target proteins and became deep red when the targets were absent. Expression of CD63, epithelial cell adhesion molecules (EpCAM), and mucin1 in EVs derived from two breast cancer cell lines (MCF-7 and MDA-MB-231) were compared, showing results consistent with western blotting results. The colorimetric assay achieves a limit of detection (LOD) down to 0.7 ng μL^-1 against MCF-7 EVs based on the assessment of EpCAM expression, suggesting its potential to be applied in clinical breast cancer diagnosis.

Scavenger receptor MARCO contributes to cellular internalization of exosomes by dynamin-dependent endocytosis and macropinocytosis

Macrophage receptor with collagenous structure (MARCO) is a scavenger receptor class-A protein that is expressed on the cell surface of macrophages. MARCO mediates binding and ingestion of unopsonized environmental particles, including nano-sized materials. Exosomes are cell-derived, nano-sized vesicles (40–150 nm) that can contain lipids, RNA, DNA, and various proteins. Exosomes play an essential role in cell-to-cell communication via body fluids. However, mechanisms for the recognition and internalization of exosomes by recipient cells remain poorly characterized. In this study, cellular association of serum-derived fluorescent exosomes and 20-nm fluorescent nanoparticles (positive control) was compared between MARCO-expressing (CHO-MARCO) and control (CHO-CT) CHO-K1 cells to examine whether MARCO expression by recipient cells mediates the cellular uptake of exosomes and environmental nanoparticles. Fluorescence microscopic studies and quantitative analyses revealed that the cellular associations of both exosomes and 20-nm nanoparticles were greater in CHO-MARCO cells than in CHO-CT cells. Exosomes and nanoparticles colocalized with green fluorescent protein (GFP)-MARCO in cells transfected with GFP-MARCO-encoding constructs . Furthermore, inhibitory studies showed that actin reorganization and dynamin are involved in the MARCO-mediated cellular internalization of exosomes. These results indicated that MARCO plays a role in the uptake of exosomes.

MicroRNA‑34a‑5p expression in the plasma and in its extracellular vesicle fractions in subjects with Parkinson's disease: An exploratory study

Parkinson's disease (PD) is an important disabling age-related disorder and is the second most common neuro-degenerative disease. Currently, no established molecular biomarkers exist for the early diagnosis of PD. Circulating microRNAs (miRNAs), either vesicle-free or encapsulated in extracellular vesicles (EVs), have emerged as potential blood-based biomarkers also for neurodegenerative diseases. In this exploratory study, we focused on miR-34a-5p because of its well-documented involvement in neurobiology. To explore a differential profile of circulating miR-34a-5p in PD, PD patients and age-matched control subjects were enrolled. Serial ultracentrifugation steps and density gradient were used to separate EV subpopulations from plasma according to their different sedimentation properties (Large, Medium, Small EVs). Characterization of EV types was performed using western blotting and atomic force microscopy (AFM); purity from protein contaminants was checked with the colorimetric nanoplasmonic assay. Circulating miR-34a-5p levels were evaluated using qPCR in plasma and in each EV type. miR-34a-5p was significantly up-regulated in small EVs devoid of exogenous protein contaminants (pure SEVs) from PD patients and ROC analysis indicated a good diagnostic performance in discriminating patients from controls (AUC=0.74, P<0.05). Moreover, miR-34a-5p levels in pure SEVs were associated with disease duration, Hoehn and Yahr and Beck Depression Inventory scores. These results under-line the necessity to examine the miRNA content of each EV subpopulation to identify miRNA candidates with potential diagnostic value and lay the basis for future studies to validate the overexpression of circulating miR-34a-5p in PD via the use of pure SEVs.

Recent advances in nanomaterial-based biosensors for the detection of exosomes

Exosomes are a type of extracellular vesicle actively secreted by almost all eukaryotic cells. They are ideal candidates for reliable next-generation biomarkers in the early diagnosis and therapeutic response evaluation of cancer. Thus, the quantification of exosomes is crucial in facilitating clinical research and application. Compared with traditional materials, nanomaterials have better optical, magnetic, electrical, and catalytic properties due to their small size, high specific surface area, and variable structure. The incorporation of nanomaterials into sensing systems is an attractive approach towards improving sensitivity and can provide improved sensor selectivity and stability. In this paper, we summarize the progress in nanomaterial-based exosome detection methods, including electrochemical biosensors, photoelectrochemical biosensors, colorimetric biosensors, fluorescence biosensors, chemiluminescence biosensors, electrochemiluminescence biosensors, surface plasmon resonance biosensors, and surface-enhanced Raman spectroscopy biosensors. Moreover, future research directions and challenges in exosome detection methods are discussed. We hope that this article will offer an overview of nanomaterial-based exosome detection techniques and open new avenues in disease research.Graphical abstract.

Employing Flow Cytometry to Extracellular Vesicles Sample Microvolume Analysis and Quality Control

Extracellular Vesicles (EVs), membrane vesicles released by all cells, are emerging mediators of cell-cell communication. By carrying biomolecules from tissues to biofluids, EVs have attracted attention as non-invasive sources of clinical biomarkers in liquid biopsies. EVs-based liquid biopsies usually require EVs isolation before content analysis, which frequently increases sample volume requirements. We here present a Flow Cytometry (FC) strategy that does not require isolation or concentration of EVs prior to staining. By doing so, it enables population analysis of EVs in samples characterized by challenging small volumes, while reducing overall sample processing time. To illustrate its application, we performed longitudinal non-lethal population analysis of EVs in mouse plasma and in single-animal collections of murine vitreous humor. By quantifying the proportion of vesicular particles in purified and non-purified biological samples, this method also serves as a precious tool to quality control isolates of EVs purified by different protocols. Our FC strategy has an unexplored clinical potential to analyze EVs in biofluids with intrinsically limited volumes and to multiply the number of different analytes in EVs that can be studied from a single collection of biofluid.

Easy colorimetric detection of gadolinium ions based on gold nanoparticles: key role of phosphine-sulfonate ligands

The possibility to easily and rapidly assess the presence of Gd³⁺ ions in solution is of paramount importance in many domains like magnetic resonance imaging. In that context, the use of easy to implement colorimetric sensing probes based on gold nanoparticles (AuNPs) is of special interest. Herein, AuNPs functionalized with a commercial bis(p-sulfonatophenyl)phenyl phosphine ligand (BSPP) (AuNP@BSPP), bearing negatively charged sulfonate groups are used as a colorimetric sensing probe. The addition of Gd³⁺ ions onto these NPs was studied through UV-visible absorbance measurements, Quartz Crystal Microbalance with Dissipation monitoring (QCM-D) and transmission electron microscopy and compared with citrate covered AuNPs. We evidenced interactions between the Gd³⁺ ions and their water rich coordination sphere and sulfonate groups on the surface of AuNP@BSPP via electrostatic interactions and hydrogen bonding. These interactions induce the reversible aggregation of AuNP@BSPP in the presence of concentrations of Gd³⁺ ions at a μM level. We took advantage of this phenomenon to develop a simple and fast bench colorimetric assay for the detection of free Gd³⁺ ions, based on the determination of a flocculation parameter thanks to UV-visible measurements. Limits of detection and quantification were found equal to 0.74 μM and 4.76 μM of Gd³⁺ ions, respectively, with a high sensitivity that competes with conventional methods used for lanthanide detection.

The future of Extracellular Vesicles as Theranostics - an ISEV meeting report

The utilization of extracellular vesicles (EVs) in clinical theranostics has rapidly advanced in the past decade. In November 2018, the International Society for Extracellular Vesicles (ISEV) held a workshop on “EVs in Clinical Theranostic”. Here, we report the conclusions of roundtable discussions on the current advancement in the analysis technologies and we provide some guidelines to researchers in the field to consider the use of EVs in clinical application. The main challenges and the requirements for EV separation and characterization strategies, quality control and clinical investigation were discussed to promote the application of EVs in future clinical studies.

Effect of the Surface Chemical Composition and of Added Metal Cation Concentration on the Stability of Metal Nanoparticles Synthesized by Pulsed Laser Ablation in Water

Metal nanoparticles (NPs) made of gold, silver, and platinum have been synthesized by means of pulsed laser ablation in liquid aqueous solution. Independently from the metal nature, all NPs have an average diameter of 10 ± 5 nm. The ζ-potential values are: −62 ± 7 mV for gold, −44 ± 2 mV for silver and −58 ± 3 for platinum. XPS analysis demonstrates the absence of metal oxides in the case of gold and silver NPs. In the case of platinum NPs, 22% of the particle surface is ascribed to platinum oxidized species. This points to a marginal role of the metal oxides in building the negative charge that stabilizes these colloidal suspensions. The investigation of the colloidal stability of gold NPs in the presence of metal cations shows these NPs can be destabilized by trace amounts of selected metal ions. The case of Ag+ is paradigmatic since it is able to reduce the NP ζ-potential and to induce coagulation at concentrations as low as 3 μM, while in the case of K+ the critical coagulation concentration is around 8 mM. It is proposed that such a huge difference in destabilization power between monovalent cations can be accounted for by the difference in the reduction potential.

Methods for the Determination of the Purity of Exosomes

BACKGROUND

Exosomes open exciting new opportunities for advanced drug transport and targeted release. Furthermore, exosomes may be used for vaccination, immunosuppression or wound healing. To fully utilize their potential as drug carriers or immune-modulatory agents, the optimal purity of exosome preparations is of crucial importance.

METHODS

Articles describing the isolation and purification of exosomes were retrieved from the PubMed database.

RESULTS

Exosomes are often separated from biological fluids containing high concentrations of proteins, lipids and other molecules that keep vesicle purification challenging. A great number of purification protocols have been published, however, their outcome is difficult to compare because the assessment of purity has not been standardized. In this review, we first give an overview of the generation and composition of exosomes, as well as their multifaceted biological functions that stimulated various medical applications. Finally, we describe various methods that have been used to purify small vesicles and to assess the purity of exosome preparations and critically compare the quality of these evaluation protocols.

CONCLUSION

Combinations of various techniques have to be applied to reach the required purity and quality control of exosome preparations.

Non-contact microfluidic mechanical property measurements of single apoptotic bodies

BACKGROUND

Cells exchange information by secreting micro- and nanosized extracellular vesicles (EVs), ranging from exosomes (30-100 nm) to apoptotic bodies (ABs, 1-5 μm). There is still much to understand about fundamental EV biological, physical, and chemical properties before clinical applications can be developed. EV mechanical properties have only been measured with atomic force microscopy (AFM) with its problematic adhesion and hard substrate effects. To understand EV mechanical behavior in less extreme mechanical conditions relevant to blood flow and many soft tissue environments, a non-contact measurement technique is needed.

METHODS

We measured the mechanical properties of single microscale ABs derived from human blood plasma using non-contact microfluidics. EVs were gently stretched in extensional flow, similar to a traditional tensile test, and a linear mechanical model was applied to estimate mechanical stiffnesses from the observed stretching.

RESULTS

The effective shear elastic modulus of ABs in non-contact flow conditions is approximately 5.6 ± 0.5 Pa, 7 orders of magnitude lower than previously reported AFM-measured biological exosome stiffnesses and 200 times smaller than suspended cells.

CONCLUSIONS

Apoptotic bodies are very soft in fluid environments and exhibit lower effective stiffnesses than suspended cells. By measuring ABs in a natural fluid environment and low-force regime without hard probes and surfaces, we achieved closer agreement with linear mechanical theory and therefore more accurate stiffness measurements.

GENERAL SIGNIFICANCE

AFM manufacturers and users should consider implementing new mechanical models to interpret AFM force indentation curves so that accurate extracellular vesicle mechanical properties can be extracted.

Extracellular Vesicles: Current Analytical Techniques for Detection and Quantification

Since their first observation, understanding the biology of extracellular vesicles (EV) has been an important and challenging field of study. They play a key role in the intercellular communication and are involved in important physiological and pathological functions. Therefore, EV are considered as potential biomarkers for diagnosis, prognosis, and monitoring the response to treatment in some diseases. In addition, due to their properties, EV may be used for therapeutic purposes. In the study of EV, three major points have to be addressed: 1. How to isolate EV from cell culture supernatant/biological fluids, 2. how to detect them, and 3. how to characterize and quantify. In this review, we focus on the last two questions and provide the main analytical techniques up-to-date for detection and profiling of EV. We critically analyze the advantages and disadvantages of each one, aimed to be of relevance for all researchers working on EV biology and their potential applications.

Optical, electrochemical and electrical (nano)biosensors for detection of exosomes: A comprehensive overview

Exosomes are small extracellular vesicles involved in many physiological activities of cells in the human body. Exosomes from cancer cells have great potential to be applied in clinical diagnosis, early cancer detection and target identification for molecular therapy. While this field is gaining increasing interests from both academia and industry, barriers such as supersensitive detection techniques and highly-efficient isolation methods remain. In the clinical settings, there is an urgent need for rapid analysis, reliable detection and point-of-care testing (POCT). With these challenges to be addressed, this article aims to review recent developments and technical breakthroughs including optical, electrochemical and electrical biosensors for exosomes detection in the field of cancer and other diseases and demonstrate how nanobiosensors could enhance the performance of conventional sensors. Working strategies, limit of detections, advantages and shortcomings of the studies are summarized. New trends, challenges and future perspectives of exosome-driven POCT in liquid biopsy have been discussed.

The nanostructured secretome

The term secretome, which traditionally strictly refers to single proteins, should be expanded to also include the great variety of nanoparticles secreted by cells (secNPs) into the extracellular space, which ranges from high-density lipoproteins of a few nanometers to extracellular vesicles and fat globules of hundreds of nanometers. Widening the definition is urged by the ever-increasing understanding of the role of secNPs as regulators/mediators of key physiological and pathological processes, which also puts them in the running as breakthrough cell-free therapeutics and diagnostics. "Made by cells for cells", secNPs are envisioned as a sweeping paradigm shift in nanomedicine, promising to overcome the limitations of synthetic nanoparticles by unsurpassed circulation and targeting abilities, precision and sustainability. From a longer/wider perspective, advanced manipulation would possibly make secNPs available as building blocks for future "biogenic" nanotechnology. However, the current knowledge is fragmented and sectorial (the majority of the studies being focused on a specific biological and/or medical aspect of a given secNP class or subclass), the understanding of the nanoscale and interfacial properties is limited and the development of bioprocesses and regulatory initiatives is in the early days. We believe that new multidisciplinary competencies and synergistic efforts need to be attracted and augmented to move forward. This review will contribute to the effort by attempting for the first time to rationally gather and elaborate secNPs and their traits into a unique concise framework - from biogenesis to colloidal properties, engineering and clinical translation - disclosing the overall view and easing comparative analysis and future exploitation.

Fourier-transform Infrared (FT-IR) spectroscopy fingerprints subpopulations of extracellular vesicles of different sizes and cellular origin

Identification of extracellular vesicle (EV) subpopulations remains an open challenge. To date, the common strategy is based on searching and probing set of molecular components and physical properties intended to be univocally characteristics of the target subpopulation. Pitfalls include the risk to opt for an unsuitable marker set – which may either not represent the subpopulation or also cover other unintended subpopulations – and the need to use different characterization techniques and equipment. This approach focused on specific markers may result inadequate to routinely deal with EV subpopulations that have an intrinsic high level of heterogeneity. In this paper, we show that Fourier-transform Infrared (FT-IR) spectroscopy can provide a collective fingerprint of EV subpopulations in one single experiment. FT-IR measurements were performed on large (LEVs, ~600 nm), medium (MEVs, ~200 nm) and small (SEVs ~60 nm) EVs enriched from two different cell lines medium: murine prostate cancer (TRAMP-C2) and skin melanoma (B16). Spectral regions between 3100–2800 cm⁻¹ and 1880–900 cm⁻¹, corresponding to functional groups mainly ascribed to lipid and protein contributions, were acquired and processed by Principal Component Analysis (PCA). LEVs, MEVs and SEVs were separately grouped for both the considered cell lines. Moreover, subpopulations of the same size but from different sources were assigned (with different degrees of accuracy) to two different groups. These findings demonstrate that FT-IR has the potential to quickly fingerprint EV subpopulations as a whole, suggesting an appealing complement/alternative for their characterization and grading, extendable to healthy and pathological EVs and fully artificial nanovesicles.

Extracellular vesicles from rat-bone-marrow mesenchymal stromal/stem cells improve tendon repair in rat Achilles tendon injury model in dose-dependent manner: A pilot study

Mesenchymal stromal/stem cells (MSCs) are increasingly employed for tissue regeneration, largely mediated through paracrine actions. Currently, extracellular vesicles (EVs) released by MSCs are major mediators of these paracrine effects. We evaluated whether rat-bone-marrow-MSC-derived EVs (rBMSCs-EVs) can ameliorate tendon injury in an in vivo rat model. Pro-collagen1A2 and MMP14 protein are expressed in rBMSC-EVs, and are important factors for extracellular-matrix tendon-remodeling. In addition, we found pro-collagen1A2 in rBMSC-EV surface-membranes by dot blot. In vitro on cells isolated from Achilles tendons, utilized as rBMSC -EVs recipient cells, EVs at both low and high doses induce migration of tenocytes; at higher concentration, they induce proliferation and increase expression of Collagen type I in tenocytes. Pretreatment with trypsin abrogate the effect of EVs on cell proliferation and migration, and the expression of collagen I. When either low- or high-dose rBMSCs-EVs were injected into a rat-Achilles tendon injury-model (immediately after damage), at 30 days, rBMSC-EVs were found to have accelerated the remodeling stage of tendon repair in a dose-dependent manner. At histology and histomorphology evaluation, high doses of rBMSCs-EVs produced better restoration of tendon architecture, with optimal tendon-fiber alignment and lower vascularity. Higher EV-concentrations demonstrated greater expression of collagen type I and lower expression of collagen type III. BMSC-EVs hold promise as a novel cell-free modality for the management of tendon injuries.

Augmented COlorimetric NANoplasmonic (CONAN) Method for Grading Purity and Determine Concentration of EV Microliter Volume Solutions

This protocol paper describes how to assign a purity grade and to subsequently titrate extracellular vesicle (EV) solutions of a few microliters in volume by microplate COlorimetric NANoplasmonic (CONAN) assay. The CONAN assay consists of a solution of gold nanoparticles (AuNPs) into which the EV preparation is added. The solution turns blue if the EV preparation is pure, whereas it stays red if soluble exogenous single and aggregated proteins (SAPs; often referred to as protein contaminants) are present. The color change is visible by the naked eye or can be quantified by UV-Vis spectroscopy, providing an index of purity (a unique peculiarity to date). The assay specifically targets SAPs, and not the EV-related proteins, with a detection limit <50 ng/μl (an order of magnitude higher resolution than that of the Bradford protein assay). For pure solutions, the assay also allows for determining the EV number, as the color shift is linearly dependent on the AuNP/EV molar ratio. Instead, it automatically reports if the solution bears SAP contaminants, thus avoiding counting artifacts. The CONAN assay proves to be robust and reliable and displays very interesting performances in terms of cost (inexpensive reagents, run by standard microplate readers), working volumes (1–2 μl of sample required), and time (full procedure takes <1 h). The assay is applicable to all classes of natural and artificial lipid microvesicles and nanovesicles.

Isolation and analysis of extracellular vesicles in a Morpho butterfly wing-integrated microvortex biochip

With the function of mediating intercellular communication between cells, extracellular vesicles (EVs) have been intently studied for their physiopathology and clinical application values. However, efficient EV isolation from biological fluids remains a significant challenge. To address this, this work constructs a new microvortex chip that can isolate EVs efficiently by integrating the lipid nanoprobe modified Morpho Menelaus (M. Menelaus) butterfly wing into microfluidic chip. M. Menelaus wing is well known for its orderly arranged periodic nanostructures and can generate microvortex when liquid passes through it, leading to increased interaction between EVs and M. Menelaus wing. In addition, the nanoprobe containing lipid tails can be inserted into EVs through their lipid bilayer membrane structure. Based on the described properties, high-throughput enrichment of EVs with over 70% isolation efficiency was realized. Moreover, it was demonstrated that the nanoprobe system based on M. Menelaus wing enabled downstream biological analysis of nucleic acids and proteins in EVs. Microvortex chips showed potential application value in efficient EV isolation for biomedical research and cancer diagnosis.

Nanoparticles and organized lipid assemblies: from interaction to design of hybrid soft devices

This contribution reviews the state of art on hybrid soft matter assemblies composed of inorganic nanoparticles (NP) and lamellar or non-lamellar lipid bilayers. After a short outline of the relevant energetic contributions, we address the interaction of NPs with synthetic lamellar bilayers, meant as cell membrane mimics. We then review the design of hybrid nanostructured materials composed of lipid bilayers and some classes of inorganic NPs, with particular emphasis on the effects on the amphiphilic phase diagram and on the additional properties contributed by the NPs. Then, we present the latest developments on the use of lipid bilayers as coating agents for inorganic NPs. Finally, we remark on the main achievements of the last years and our vision for the development of the field.

Biological membranes in EV biogenesis, stability, uptake, and cargo transfer: an ISEV position paper arising from the ISEV membranes and EVs workshop

Paracrine and endocrine roles have increasingly been ascribed to extracellular vesicles (EVs) generated by multicellular organisms. Central to the biogenesis, content, and function of EVs are their delimiting lipid bilayer membranes. To evaluate research progress on membranes and EVs, the International Society for Extracellular Vesicles (ISEV) conducted a workshop in March 2018 in Baltimore, Maryland, USA, bringing together key opinion leaders and hands-on researchers who were selected on the basis of submitted applications. The workshop was accompanied by two scientific surveys and covered four broad topics: EV biogenesis and release; EV uptake and fusion; technologies and strategies used to study EV membranes; and EV transfer and functional assays. In this ISEV position paper, we synthesize the results of the workshop and the related surveys to outline important outstanding questions about EV membranes and describe areas of consensus. The workshop discussions and survey responses reveal that while much progress has been made in the field, there are still several concepts that divide opinion. Good consensus exists in some areas, including particular aspects of EV biogenesis, uptake and downstream signalling. Areas with little to no consensus include EV storage and stability, as well as whether and how EVs fuse with target cells. Further research is needed in these key areas, as a better understanding of membrane biology will contribute substantially towards advancing the field of extracellular vesicles.

Nanoplasmonic Approaches for Sensitive Detection and Molecular Characterization of Extracellular Vesicles

All cells release a multitude of nanoscale extracellular vesicles (nEVs) into circulation, offering immense potential for new diagnostic strategies. Yet, clinical translation for nEVs remains a challenge due to their vast heterogeneity, our insufficient ability to isolate subpopulations, and the low frequency of disease-associated nEVs in biofluids. The growing field of nanoplasmonics is poised to address many of these challenges. Innovative materials engineering approaches based on exploiting nanoplasmonic phenomena, i.e., the unique interaction of light with nanoscale metallic materials, can achieve unrivaled sensitivity, offering real-time analysis and new modes of medical and biological imaging. We begin with an introduction into the basic structure and function of nEVs before critically reviewing recent studies utilizing nanoplasmonic platforms to detect and characterize nEVs. For the major techniques considered, surface plasmon resonance (SPR), localized SPR, and surface enhanced Raman spectroscopy (SERS), we introduce and summarize the background theory before reviewing the studies applied to nEVs. Along the way, we consider notable aspects, limitations, and considerations needed to apply plasmonic technologies to nEV detection and analysis.

Raman spectroscopy as a quick tool to assess purity of extracellular vesicle preparations and predict their functionality

Extracellular vesicles (EVs) from a variety of stem cell sources are believed to harbour regenerative capacity, which may be exploited for therapeutic purposes. Because of EV interaction with other soluble secreted factors, EV activity may depend on the employed purification method, which limits cross-study comparisons and therapeutic development. Raman spectroscopy (RS) is a quick and easy method to assess EV purity and composition, giving in-depth biochemical overview on EV preparation. Hereby, we show how this method can be used to characterise EVs isolated from human liver stem cells and bone marrow mesenchymal stem/stromal cells by means of conventional ultracentrifugation (UC) and size exclusion chromatography (SEC) protocols. The obtained EV preparations were demonstrated to be characterised by different degrees of purity and a specific Raman fingerprint that represents both the cell source and the isolation procedure used. Moreover, RS provided useful hints to explore the factors underlying the functional diversity of EV preparations from the same cell source, thus representing a valuable tool to assess EV quality prior to functional assays or therapeutic application.

Minimal information for studies of extracellular vesicles 2018 (MISEV2018): a position statement of the International Society for Extracellular Vesicles and update of the MISEV2014 guidelines

The last decade has seen a sharp increase in the number of scientific publications describing physiological and pathological functions of extracellular vesicles (EVs), a collective term covering various subtypes of cell-released, membranous structures, called exosomes, microvesicles, microparticles, ectosomes, oncosomes, apoptotic bodies, and many other names. However, specific issues arise when working with these entities, whose size and amount often make them difficult to obtain as relatively pure preparations, and to characterize properly. The International Society for Extracellular Vesicles (ISEV) proposed Minimal Information for Studies of Extracellular Vesicles ("MISEV") guidelines for the field in 2014. We now update these "MISEV2014" guidelines based on evolution of the collective knowledge in the last four years. An important point to consider is that ascribing a specific function to EVs in general, or to subtypes of EVs, requires reporting of specific information beyond mere description of function in a crude, potentially contaminated, and heterogeneous preparation. For example, claims that exosomes are endowed with exquisite and specific activities remain difficult to support experimentally, given our still limited knowledge of their specific molecular machineries of biogenesis and release, as compared with other biophysically similar EVs. The MISEV2018 guidelines include tables and outlines of suggested protocols and steps to follow to document specific EV-associated functional activities. Finally, a checklist is provided with summaries of key points.

Recent Progress in Isolation and Detection of Extracellular Vesicles for Cancer Diagnostics

Extracellular vesicles (EVs) are emerging as one of the many new and promising biomarkers for liquid biopsy of cancer due to their loading capability of some specific proteins and nucleic acids that are closely associated with cancer states. As such, the isolation and detection of cancer-derived EVs offer important information in noninvasive diagnosis of early-stage cancer and real-time monitoring of cancer development. In light of the importance of EVs, over the last decade, researchers have made remarkable innovations to advance the development of EV isolation and detection methods by taking advantage of microfluidics, biomolecule probes, nanomaterials, surface plasmon, optics, and so on. This review introduces the basic properties of EVs and common cancer-derived EV ingredients, and provides a comprehensive overview of EV isolation and detection strategies, with emphasis on liquid biopsies of EVs for cancer diagnostics.

High degradation and no bioavailability of artichoke miRNAs assessed using an in vitro digestion/Caco-2 cell model

Although the cross-kingdom transfer of vegetable miRNAs (miRNAs) in mammalian species, including humans, is still controversial, recent studies have rejected this theory. Based on these recent studies, we hypothesized that artichoke-derived miRNAs (cca-miRNAs) are not adsorbed into human intestinal cells after cooking and in vitro digestion. In order to test this hypothesis, we evaluated miRNA (cca-miRNAs) in the edible part of globe artichokes (head portion), after cooking and digestion by an in vitro digestion system. The cca-miRNA levels were analyzed by real-time PCR (RT-qPCR), and those that withstood cooking and digestion conditions were further analyzed for their bioavailability using an in vitro system (Caco-2/TC7 cell clone). We detected 20 cca-miRNAs after cooking, 5 of which were statistically down-regulated in comparison with uncooked samples. Only 4 cca-miRNAs were found after in vitro digestion. By using scanning electron microscopy (SEM), we also evaluated the extracellular vesicles (EVs) in homogenized artichoke as possible miRNA transporters. However, approximately 81% were degraded after cooking, while the remaining EVs had changed shape from round to elliptical. Finally, we detected no cell-free cca-miRNAs, miRNAs bound to protein complex, and no cca-miRNAs encapsulated in EVs inside Caco-2 cells or in basolateral medium after bioavailability experiments. In conclusion, the data from the present study agrees with recent findings that the human small intestine does not uptake dietary miRNAs from raw or cooked artichoke heads.

Uptake Profiles of Human Serum Exosomes by Murine and Human Tumor Cells through Combined Use of Colloidal Nanoplasmonics and Flow Cytofluorimetric Analysis

Understanding extracellular vesicle (EV) internalization mechanisms and pathways in cells is of capital importance for both EV basic biology and clinical translation, but still presents analytical hurdles, such as undetermined purity grade and/or concentration of the EV samples and lack of standard protocols. We report an accessible, robust, and versatile method for resolving dose-dependent uptake profiles of exosomes-the nanosized (30-150 nm) subtypes of EVs of intracellular origin which are more intensively investigated for diagnostic and therapeutic applications-by cultured cells. The method is based on incubating recipient cells with consistently increasing doses of exosomes which are graded for purity and titrated by a COlorimetric NANoplasmonic (CONAN) assay followed by cell flow cytofluorimetric analysis. The proposed method allowed evaluation and comparison of the uptake of human serum exosomes by cancer cell lines of murine (TRAMP-C2) and human (LNCaP, DU145, MDA-MB-231, and A375) origin, setting a firmer footing for better characterization and understanding of exosome biology in different in vitro and (potentially) in vivo models of cancer growth.

Exosome-delivered microRNAs promote IFN-α secretion by human plasmacytoid DCs via TLR7

The excessive production of type I IFNs is a hallmark and a main pathogenic mechanism of many autoimmune diseases, including systemic lupus erythematosus (SLE). In these pathologies, the sustained secretion of type I IFNs is dependent on the improper activation of plasmacytoid DCs (pDCs) by self-nucleic acids. However, the nature and origin of pDC-activating self-nucleic acids is still incompletely characterized. Here, we report that exosomes isolated from the plasma of SLE patients can activate the secretion of IFN-α by human blood pDCs in vitro. This activation requires endosomal acidification and is recapitulated by microRNAs isolated from exosomes, suggesting that exosome-delivered microRNAs act as self-ligands of innate single-stranded endosomal RNA sensors. By using synthetic microRNAs, we identified an IFN induction motif that is responsible for the TLR7-dependent activation, maturation, and survival of human pDCs. These findings identify exosome-delivered microRNAs as potentially novel TLR7 endogenous ligands able to induce pDC activation in SLE patients. Therefore, microRNAs may represent novel pathogenic mediators in the onset of autoimmune reactions and potential therapeutic targets in the treatment of type I IFN-mediated diseases.

The influence of tumour-derived extracellular vesicles on local and distal metastatic dissemination

Extracellular vesicles (EVs) are key mediators of intercellular communication that have been ignored for decades. Tumour cells benefit from the secretion of vesicles as they can influence the behaviour of neighbouring tumour cells within the tumour microenvironment. Several studies have shown that extracellular vesicles play an active role in pre-metastatic niche formation and importantly, they are involved in the metastatic organotropism of different tumour types. Tumour-derived EVs carry and transfer molecules to recipient cells, modifying their behaviour through a process defined as "EV-driven education". EVs favour metastasis to sentinel lymph nodes and distal organs by reinforcing angiogenesis, inflammation and lymphangiogenesis. Hence, in this review we will summarize the main mechanisms by which tumour-derived EVs regulate lymph node and distal organ metastasis. Moreover, since some cancers metastasize through the lymphatic system, we will discuss recent discoveries about the presence and function of tumour EVs in the lymph. Finally, we will address the potential value of tumour EVs as prognostic biomarkers in liquid biopsies, specially blood and lymphatic fluid, and the use of these tools as early detectors of metastases.