Size Separation of Exosomes and Microvesicles Using Flow Field-Flow Fractionation/Multiangle Light Scattering and Lipidomic Comparison

Isolation and quantification of human urinary exosomes using a Tween-20 elution solvent from polyester, capillary-channeled polymer fiber columns

BACKGROUND

Exosomes, a subset of extracellular vesicles (EVs), are a type of membrane-secreted vesicle essential for intercellular communication. There is a great deal of interest in developing methods to isolate and quantify exosomes to study their role in intercellular processes and as potential therapeutic delivery systems. Polyester, capillary-channeled polymer fiber columns and spin-down tips are highly efficient, low-cost means of exosome isolation. As the methodology evolves, there remain questions as to the optimum elution solvent for specific end-uses of the recovered vesicles; fundamental biochemistry, clinical diagnostics, or therapeutic vectors.

RESULTS

While both acetonitrile and glycerol have been proven highly successful in terms of EV recoveries in the hydrophobic interaction chromatography workflow, many biological studies entail the use of the non-ionic detergent, Tween-20, as a working solvent. Here we evaluate the use of Tween-20 as the elution solvent for the recovery of exosomes. A novel 10-min, two-step gradient elution method, employing 0.1 % v/v Tween-20, efficiently isolated EVs at a concentration of ∼1011 EV mL-1 from a 100 μL urine injection. Integration of absorbance and multi-angle light scattering detectors in standard HPLC instrumentation enables a comprehensive single-injection determination of eluted exosome concentration and sizes. Transmission electron microscopy verifies the retention of the vesicular structure of the exosomes. The micro-bicinchoninic acid protein quantification assay confirmed high-purity isolations of exosomes (∼99 % removal of background proteins) SIGNIFICANCE: The effective use of Tween-20 as an elution solvent for exosome isolation/purification using capillary-channeled polymer fiber columns adds greater versatility to the portfolio of the approach. The proposed method holds promise for a wide range of fundamental biochemistry, clinical diagnostics, and therapeutic applications, marking a significant advancement in EV-based methodologies.

RNA nanotherapeutics with fibrosis overexpression and retention for MASH treatment

Metabolic dysfunction-associated steatohepatitis (MASH) poses challenges for targeted delivery and retention of therapeutic proteins due to excess extracellular matrix (ECM). Here we present a new approach to treat MASH, termed "Fibrosis overexpression and retention (FORT)". In this strategy, we design (1) retinoid-derivative lipid nanoparticle (LNP) to enable enhanced mRNA overexpression in fibrotic regions, and (2) mRNA modifications which facilitate anchoring of therapeutic proteins in ECM. LNPs containing carboxyl-retinoids, rather than alcohol- or ester-retinoids, effectively deliver mRNA with over 10-fold enhancement of protein expression in fibrotic livers. The carboxyl-retinoid rearrangement on the LNP surface improves protein binding and membrane fusion. Therapeutic proteins are then engineered with an endogenous collagen-binding domain. These fusion proteins exhibit increased retention in fibrotic lesions and reduced systemic toxicity. In vivo, fibrosis-targeting LNPs encoding fusion proteins demonstrate superior therapeutic efficacy in three clinically relevant male-animal MASH models. This approach holds promise in fibrotic diseases unsuited for protein injection.

Electric Field Assisted Tangential Flow Filtration Device for Highly Effective Isolation of Bioactive Small Extracellular Vesicles from Cell Culture Medium

Small extracellular vesicles (sEVs) are proven to hold great promise for diverse therapeutic and diagnostic applications. However, batch preparation of sEVs with high purity and bioactivity is a prerequisite for their clinical translations. Herein, we present an electric field assisted tangential flow filtration system (E-TFF), which integrates size-based filtration with electrophoretic migration-based separation to synergistically achieve the isolation of high-quality sEVs from cell culture medium. Compared with the gold-standard ultracentrifugation (UC) method, E-TFF not only improved the purity of sEVs by 1.4 times but also increased the yield of sEVs by 15.8 times. Additionally, the entire isolation process of E-TFF was completed within 1 h, about one-fourth of the time taken by UC. Furthermore, the biological activity of sEVs isolated by E-TFF was verified by co-incubation of sEVs derived from human umbilical cord mesenchymal stem cells (hUCMSCs) with HT22 mouse hippocampal neuronal cells exposed to amyloid-β (Aβ). The results demonstrated that the sEVs isolated by E-TFF exhibited a significant neuroprotective effect. Overall, the E-TFF platform provides a promising and robust strategy for batch preparation of high-quality sEVs, opening up a broad range of opportunities for cell-free therapy and precision medicine.

Native characterization and QC profiling of human amniotic mesenchymal stromal cell vesicular fractions for secretome-based therapy

Human amniotic mesenchymal stromal cells (hAMSCs) have unique immunomodulatory properties making them attractive candidates for regenerative applications in inflammatory diseases. Most of their beneficial properties are mediated through their secretome. The bioactive factors concurring to its therapeutic activity are still unknown. Evidence suggests synergy between the two main components of the secretome, soluble factors and vesicular fractions, pivotal in shifting inflammation and promoting self-healing. Biological variability and the absence of quality control (QC) protocols hinder secretome-based therapy translation to clinical applications. Moreover, vesicular secretome contains a multitude of particles with varying size, cargos and functions whose complexity hinders full characterization and comprehension. This study achieved a significant advancement in secretome characterization by utilizing native, FFF-based separation and characterizing extracellular vesicles derived from hAMSCs. This was accomplished by obtaining dimensionally homogeneous fractions then characterized based on their protein content, potentially enabling the identification of subpopulations with diverse functionalities. This method proved to be successful as an independent technique for secretome profiling, with the potential to contribute to the standardization of a qualitative method. Additionally, it served as a preparative separation tool, streamlining populations before ELISA and LC-MS characterization. This approach facilitated the categorization of distinctive and recurring proteins, along with the identification of clusters associated with vesicle activity and functions. However, the presence of proteins unique to each fraction obtained through the FFF separation tool presents a challenge for further analysis of the protein content within these cargoes.

Extracellular Vesicle Preparation and Analysis: A State-of-the-Art Review

In recent decades, research on Extracellular Vesicles (EVs) has gained prominence in the life sciences due to their critical roles in both health and disease states, offering promising applications in disease diagnosis, drug delivery, and therapy. However, their inherent heterogeneity and complex origins pose significant challenges to their preparation, analysis, and subsequent clinical application. This review is structured to provide an overview of the biogenesis, composition, and various sources of EVs, thereby laying the groundwork for a detailed discussion of contemporary techniques for their preparation and analysis. Particular focus is given to state-of-the-art technologies that employ both microfluidic and non-microfluidic platforms for EV processing. Furthermore, this discourse extends into innovative approaches that incorporate artificial intelligence and cutting-edge electrochemical sensors, with a particular emphasis on single EV analysis. This review proposes current challenges and outlines prospective avenues for future research. The objective is to motivate researchers to innovate and expand methods for the preparation and analysis of EVs, fully unlocking their biomedical potential.

Blood-Derived Extracellular Vesicles as a Promising Liquid Biopsy Diagnostic Tool for Early Cancer Detection

Cancer poses a significant public health challenge worldwide, and timely screening has the potential to mitigate cancer progression and reduce mortality rates. Currently, early identification of most tumors relies on imaging techniques and tissue biopsies. However, the use of low-cost, highly sensitive, non-invasive detection methods for early cancer screening has become more attractive. Extracellular Vesicles (EVs) released by all living cells contain distinctive biological components, such as nucleic acids, proteins, and lipids. These vesicles play crucial roles in the tumor microenvironment and intercellular communication during tumor progression, rendering liquid biopsy a particularly suitable method for diagnosis. Nevertheless, challenges related to purification methods and validation of efficacy currently hinder its widespread clinical implementation. These limitations underscore the importance of refining isolation techniques and conducting comprehensive investigations on EVs. This study seeks to evaluate the potential of liquid biopsy utilizing blood-derived EVs as a practical, cost-effective, and secure approach for early cancer detection.

Small and Large Extracellular Vesicles of Porcine Seminal Plasma Differ in Lipid Profile

Seminal plasma contains a heterogeneous population of extracellular vesicles (sEVs) that remains poorly characterized. This study aimed to characterize the lipidomic profile of two subsets of differently sized sEVs, small (S-) and large (L-), isolated from porcine seminal plasma by size-exclusion chromatography and characterized by an orthogonal approach. High-performance liquid chromatography-high-resolution mass spectrometry was used for lipidomic analysis. A total of 157 lipid species from 14 lipid classes of 4 major categories (sphingolipids, glycerophospholipids, glycerolipids, and sterols) were identified. Qualitative differences were limited to two cholesteryl ester species present only in S-sEVs. L-sEVs had higher levels of all quantified lipid classes due to their larger membrane surface area. The distribution pattern was different, especially for sphingomyelins (more in S-sEVs) and ceramides (more in L-sEVs). In conclusion, this study reveals differences in the lipidomic profile of two subsets of porcine sEVs, suggesting that they differ in biogenesis and functionality.

Evolving Strategies for Extracellular Vesicles as Future Cardiac Therapeutics: From Macro- to Nano-Applications

Cardiovascular disease represents the foremost cause of mortality and morbidity worldwide, with a steadily increasing incidence due to the growth of the ageing population. Cardiac dysfunction leading to heart failure may arise from acute myocardial infarction (MI) as well as inflammatory- and cancer-related chronic cardiomyopathy. Despite pharmacological progress, effective cardiac repair represents an unmet clinical need, with heart transplantation being the only option for end-stage heart failure. The functional profiling of the biological activity of extracellular vesicles (EVs) has recently attracted increasing interest in the field of translational research for cardiac regenerative medicine. The cardioprotective and cardioactive potential of human progenitor stem/cell-derived EVs has been reported in several preclinical studies, and EVs have been suggested as promising paracrine therapy candidates for future clinical translation. Nevertheless, some compelling aspects must be properly addressed, including optimizing delivery strategies to meet patient needs and enhancing targeting specificity to the cardiac tissue. Therefore, in this review, we will discuss the most relevant aspects of the therapeutic potential of EVs released by human progenitors for cardiovascular disease, with a specific focus on the strategies that have been recently implemented to improve myocardial targeting and administration routes.

Proteomic profiling of mesenchymal stem cell-derived extracellular vesicles: Impact of isolation methods on protein cargo

Extracellular vesicles (EVs) are nanosized vesicles with a lipid bilayer that are secreted by cells and play a critical role in cell-to-cell communication. Despite the promising reports regarding their diagnostic and therapeutic potential, the utilization of EVs in the clinical setting is limited due to insufficient information about their cargo and a lack of standardization in isolation and analysis methods. Considering protein cargos in EVs as key contributors to their therapeutic potency, we conducted a tandem mass tag (TMT) quantitative proteomics analysis of three subpopulations of mesenchymal stem cell (MSC)-derived EVs obtained through three different isolation techniques: ultracentrifugation (UC), high-speed centrifugation (HS), and ultracentrifugation on sucrose cushion (SU). Subsequently, we checked EV marker expression, size distribution, and morphological characterization, followed by bioinformatic analysis. The bioinformatic analysis of the proteome results revealed that these subpopulations exhibit distinct molecular and functional characteristics. The choice of isolation method impacts the proteome of isolated EVs by isolating different subpopulations of EVs. Specifically, EVs isolated through the high-speed centrifugation (HS) method exhibited a higher abundance of ribosomal and mitochondrial proteins. Functional apoptosis assays comparing isolated mitochondria with EVs isolated through different methods revealed that HS-EVs, but not other EVs, induced early apoptosis in cancer cells. On the other hand, EVs isolated using the sucrose cushion (SU) and ultracentrifugation (UC) methods demonstrated a higher abundance of proteins primarily involved in the immune response, cell-cell interactions and extracellular matrix interactions. Our analyses unveil notable disparities in proteins and associated biological functions among EV subpopulations, underscoring the importance of meticulously selecting isolation methods and resultant EV subpopulations based on the intended application.

In-line coupling of capillary-channeled polymer fiber columns with optical absorbance and multi-angle light scattering detection for the isolation and characterization of exosomes

Extracellular vesicles (EVs) have garnered much interest due to their fundamental role in intracellular communication and their potential utility in clinical diagnostics and as biotherapeutic vectors. Of particular relevance is the subset of EVs referred to as exosomes, ranging in size from 30 to 150 nm, which contain incredible amounts of information about their cell of origin, which can be used to track the progress of disease. As a complementary action, exosomes can be engineered with therapeutic cargo to selectively target diseases. At present, the lack of highly efficient methods of isolation/purification of exosomes from diverse biofluids, plants, and cell cultures is a major bottleneck in the fundamental biochemistry, clinical analysis, and therapeutic applications. Equally impactful, the lack of effective in-line means of detection/characterization of isolate populations, including concentration and sizing, is limiting in the applications. The method presented here couples hydrophobic interaction chromatography (HIC) performed on polyester capillary-channeled polymer (C-CP) fiber columns followed by in-line optical absorbance and multi-angle light scattering (MALS) detection for the isolation and characterization of EVs, in this case present in the supernatant of Chinese hamster ovary (CHO) cell cultures. Excellent correlation was observed between the determined particle concentrations for the two detection methods. C-CP fiber columns provide a low-cost platform (< $5 per column) for the isolation of exosomes in a 15-min workflow, with complementary absorbance and MALS detection providing very high-quality particle concentration and sizing information.

Delineating Bovine Milk Derived Microvesicles from Exosomes Using Proteomics

In the work presented herein, a simple serial-pelleting purification strategy combined with a mass spectrometry-based proteomics analysis was developed as a means of discerning differences in extracellular vesicle (EV) populations found in bovine milk samples. A sequence of ultracentrifugation speeds was used to generate changes in the abundances of EV populations, allowing for the identification of associated proteins. A metric was developed to determine the relative abundances of proteins in large EVs (>200 nm) and small EVs (<200 nm). Of the 476 proteins consistently found in this study, 340 are associated with vesicular components. Of these, 156 were heavily enriched in large EVs, 155 shared between large and small EVs, and 29 heavily enriched in small EVs. Additionally, out of 68 proteins annotated as exosome proteins, 32 were enriched in large EVs, 27 shared between large and small EVs, 5 enriched in small EVs, and 7 were found to be nonvesicular contaminant proteins. The top correlated proteins in the small EV group were predominantly membrane-bound proteins, whereas the top correlated proteins in the large EV group were mostly cytosolic enzymes for molecular processing. This method provides a means of assessing the origins of vesicle components and provides new potential marker proteins within discrete vesicle populations.

Changes in cargoes of platelet derived extracellular vesicles heterogeneous subpopulations induced by PM0.1--Undisclosed cardiovascular injury communication mechanism

Epidemiological evidence has indicated a closely link between PM0.1 exposure and the incidence rate of cardiovascular diseases. This study explores the underlying communication roles of platelet-derived extracellular vesicles (PEVs) heterogeneous subpopulations in cardiovascular injury. PEVs and PMEVs which were extracted from platelet-rich plasma (PRP) un-exposure or exposure to PM0.1 by TIM4 affinity beads. By optimizing separation conditions, replacing pipelines, and resetting injection procedures, Asymmetric flow field-flow fractionation (AF4) was employed to separate, purify, characterize, and enrich PEVs and PMEVs heterogeneous subpopulations (small PEVs, PEVs-S/PMEVs-S: <100 nm; medium PEVs, PEVs-M/PMEVs-M: 100-200 nm; and large PEVs, PEVs-L/PMEVs-L: >200 nm). The results showed that the cargoes of PMEVs heterogeneous subpopulations which were released by PRP stimulated by PM0.1 were changed obviously. Moreover, compared with PEVs, PMEVs can lead to a decrease in the survival rate of Human Umbilical Vein Endothelial Cells (HUVECs). In PMEVs-S subpopulations, the alterations of lipids associated with membrane fusion and cell signaling transport (such as PC, Cer), as well as miRNAs related to inflammation, angiogenesis, and migration (miR-223, miR-22, miR-126, and miR-150), are similar to those in PMEVs-M subpopulations but distinct from PMEVs-L subpopulations. This study revealed the diverse communication mechanisms underlying PM0.1-induced cardiovascular injury, thereby offering potential avenues for the development of new biomarkers and therapeutic targets.

Immunological Regulation of Gut-Tropic Immune Cells by Extracellular Vesicles

The remarkable diversity of lymphocytes, essential components of the immune system, serves as an ingenious mechanism for maximizing the efficient utilization of limited host defense resources. While cell adhesion molecules, notably in gut-tropic T cells, play a central role in this mechanism, the counterbalancing molecular details have remained elusive. Conversely, we've uncovered the molecular pathways enabling extracellular vesicles secreted by lymphocytes to reach the gut's mucosal tissues, facilitating immunological regulation. This discovery sheds light on immune fine-tuning, offering insights into immune regulation mechanisms.

Field-flow fractionation - an excellent tool for fractionation, isolation and/or purification of biomacromolecules

Field-flow fractionation (FFF) with its several variants, has developed into a mature methodology. The scope of the FFF investigations has expanded, covering both a wide range of basic studies and especially a wide range of analytical applications. Special attention of this review is given to the achievements of FFF with reference to recent applications in the fractionation, isolation, and purification of biomacromolecules, and from which especially those of (in alphabetical order) bacteria, cells, extracellular vesicles, liposomes, lipoproteins, nucleic acids, and viruses and virus-like particles. In evaluating the major approaches and trends demonstrated since 2012, the most significant biomacromolecule applications are compiled in tables. It is also evident that asymmetrical flow field-flow fractionation is by far the most dominant technique in the studies. The industry has also shown current interest in FFF and adopted it in some sophisticated fields. FFF, in combination with appropriate detectors, handles biomacromolecules in open channel in a gentle way due to the lack of shear forces and unwanted interactions caused by the stationary phase present in chromatography. In addition, in isolation and purification of biomacromolecules quite high yields can be achieved under optimal conditions.

A method for extraction of exosomes from breast tumour cells and characterisation by transmission electron microscopy

Exosomes can not only be used as markers of tumour metastasis but also be used for noninvasive diagnosis of clinical diseases, which holds significant medical research value. Observing the morphology and distribution of exosomes using transmission electron microscopy (TEM) is highly significant. In this study, we use breast tumour cell (MDA-MB-231) exosomes as a representative sample and focus on the extraction and purification of exosomes, as well as the investigation of optimal conditions for the observation of exosomes using TEM. Through comparative tests, we obtained the optimal dilution concentration and staining method for TEM of exosomes, the best dilution concentration is 100 times, the best negative staining time is 1.5 min. Western blotting and scanning electron microscopy (SEM) confirmed the presence of exosome. The particle size experiment shows that the size of exosomes is mainly distributed between 60 nm and 150 nm. This method provides a reference for TEM sample preparation of subcellular structures and small molecular biomaterials other than exosomes.

Liposomes characterization for market approval as pharmaceutical products: Analytical methods, guidelines and standardized protocols

Liposomes are nano-sized lipid-based vesicles widely studied for their drug delivery capabilities. Compared to standard carries they exhibit better properties such as improved site-targeting and drug release, protection of drugs from degradation and clearance, and lower toxic side effects. At present, scientific literature is rich of studies regarding liposomes-based systems, while 14 types of liposomal products have been authorized to the market by EMA and FDA and many others have been approved by national agencies. Although the interest in nanodevices and nanomedicine has steadily increased in the last two decades the development of documentation regulating and standardizing all the phases of their development and quality control still suffers from major inadequacy due to the intrinsic complexity of nano-systems characterization. Many generic documents (Type 1) discussing guidelines for the study of nano-systems (lipidic and not) have been proposed while there is a lack of robust and standardized methods (Type 2 documents). As a result, a widespread of different techniques, approaches and methodologies are being used, generating results of variable quality and hard to compare with each other. Additionally, such documents are often subject to updates and rewriting further complicating the topic. Within this context the aim of this work is focused on bridging the gap in liposome characterization: the most recent standardized methodologies suitable for liposomes characterization are here reported (with the corresponding Type 2 documents) and revised in a short and pragmatical way focused on providing the reader with a practical background of the state of the art. In particular, this paper will put the accent on the methodologies developed to evaluate the main critical quality attributes (CQAs) necessary for liposomes market approval.

Emerging Microfluidic Tools for Simultaneous Exosomes and Cargo Biosensing in Liquid Biopsy: New Integrated Miniaturized FFF-Assisted Approach for Colon Cancer Diagnosis

The early-stage diagnosis of cancer is a crucial clinical need. The inadequacies of surgery tissue biopsy have prompted a transition to a less invasive profiling of molecular biomarkers from biofluids, known as liquid biopsy. Exosomes are phospholipid bilayer vesicles present in many biofluids with a biologically active cargo, being responsible for cell-to-cell communication in biological systems. An increase in their excretion and changes in their cargo are potential diagnostic biomarkers for an array of diseases, including cancer, and they constitute a promising analyte for liquid biopsy. The number of exosomes released, the morphological properties, the membrane composition, and their content are highly related to the physiological and pathological states. The main analytical challenge to establishing liquid biopsy in clinical practice is the development of biosensors able to detect intact exosomes concentration and simultaneously analyze specific membrane biomarkers and those contained in their cargo. Before analysis, exosomes also need to be isolated from biological fluids. Microfluidic systems can address several issues present in conventional methods (i.e., ultracentrifugation, size-exclusion chromatography, ultrafiltration, and immunoaffinity capture), which are time-consuming and require a relatively high amount of sample; in addition, they can be easily integrated with biosensing systems. A critical review of emerging microfluidic-based devices for integrated biosensing approaches and following the major analytical need for accurate diagnostics is presented here. The design of a new miniaturized biosensing system is also reported. A device based on hollow-fiber flow field-flow fractionation followed by luminescence-based immunoassay is applied to isolate intact exosomes and characterize their cargo as a proof of concept for colon cancer diagnosis.

Vitamin D Modulates Lipid Composition of Adipocyte-Derived Extracellular Vesicles Under Inflammatory Conditions

SCOPE

Adipocyte-derived extracellular vesicles (AdEVs) convey lipids that can play a role in the energy homeostasis. Vitamin D (VD) has been shown to limit the metabolic inflammation as it decreases inflammatory markers expression in adipose tissue (AT). However, VD effect on adipocytes-derived EVs has never been investigated.

METHODS AND RESULTS

Thus, the aim of this study is to evaluate the AdEVs lipid composition by LC-MS/MS approach in 3T3-L1 cells treated with VD or/and pro-inflammatory factor (tumor necrosis factor α [TNFα]). Among all lipid species, four are highlighted (glycerolipids, phospholipids, lysophospholipids, and sphingolipids) with a differential content between small (sEVs) and large EVs (lEVs). This study also observes that VD alone modulates EV lipid species involved in membrane fluidity and in the budding of membrane. EVs treated with VD under inflammatory conditions have different lipid profiles than the control group, which is more pronounced in lEVs. Indeed, 25 lipid species are significantly modulated in lEVs, compared with only seven lipid species in sEVs.

CONCLUSIONS

This study concludes that VD, alone or under inflammatory conditions, is associated with specific lipidomic signature of sEVs and lEVs. These observations reinforce current knowledge on the anti-inflammatory effect of VD.

Rapid and Highly Efficient Purification of Extracellular Vesicles Enabled by a TiO2 Hybridized Spongy-like Polymer

We developed a novel purification medium of extracellular vesicles (EVs) by constructing a spongy-like monolithic polymer kneaded with TiO2 microparticles (TiO2-hybridized spongy monolith, TiO2-SPM). TiO2-SPM was applied in a solid-phase extraction format and enabled simple, rapid, and highly efficient purification of EVs. This is due to the high permeability caused by the continuous large flow-through pores of the monolithic skeleton (median pore size; 5.21 μm) and the specific interaction of embedded TiO2 with phospholipids of the lipid bilayers. Our method also excels in efficiency and comprehensiveness, collecting small EVs (SEVs) from the same volume of a cell culture medium 130.7 times more than typical ultracentrifugation and 4.3 times more than affinity purification targeting surface phosphatidylserine by magnetic beads. The purification method was completed within 1 h with simple operations and was directly applied to serum SEVs. Finally, we demonstrated flexibility toward the shape and size of our method by depleting EVs from fetal bovine serum (FBS), which is a necessary process to prevent contamination of culture cell-derived EVs with exogenous FBS-derived EVs. Our method will eliminate the tedious and difficult purification processes of EVs, providing a universal purification platform for EV-based drug discovery and pathological diagnosis.

Emerging Roles of Using Small Extracellular Vesicles as an Anti-Cancer Drug

Small extracellular vesicles (sEVs) are emerging as a novel therapeutic strategy for cancer therapy. Tumor-cell-derived sEVs contain biomolecules that can be utilized for cancer diagnosis. sEVs can directly exert tumor-killing effects or modulate the tumor microenvironment, leading to anti-cancer effects. In this review, the application of sEVs as a diagnostic tool, drug delivery system, and active pharmaceutical ingredient for cancer therapy will be highlighted. The therapeutic efficacies of sEVs will be compared to conventional immune checkpoint inhibitors. Additionally, this review will provide strategies for sEV engineering to enhance the therapeutic efficacies of sEVs. As a bench-to-bedside application, we will discuss approaches to encourage good-manufacturing-practice-compliant industrial-scale manufacturing and purification of sEVs.

Tetraspanin 15 depletion impairs extracellular vesicle docking at target neurons

Neurons in the central nervous system release extracellular vesicles (EVs) and exosomes in response to synaptic activity to regulate physiological processes at target neurons. The intercellular transfer of proteins, mRNAs, lipids or metabolites through EVs potentially modulates the structure and function of neurons and circuits. Whereas the biogenesis of EVs, their release from donor cells, and their molecular composition have been studied extensively, the critical factors and mechanisms regulating EV interactions with target cells are incompletely understood. Here, we identified tetraspanin 15 (Tspan15) as a component of tumor susceptibility gene 101 protein (TSG101)- and CD81-positive EV fractions. Tspan15 fluorescent fusion proteins were released from donor cells and interacted with target cells together with the exosomal marker CD63. EVs collected from wildtype cortical neurons (WT-EVs) underwent similar association with target neurons derived from either wildtype (+/+) or Tspan15 knockout (-/-) mice. In contrast, target cell interactions of EVs collected from Tspan15 (-/-) cortical donor neurons (KO-EVs) were significantly impaired, as compared to WT-EVs. Our data suggest that Tspan15 is dispensable at target neuron plasma membranes, but is required at the EV surface to promote EV docking at target neurons.

Microbe-host interactions: structure and functions of Gram-negative bacterial membrane vesicles

Bacteria-host interaction is a common, relevant, and intriguing biological phenomena. The host reacts actively or passively to the bacteria themselves, their products, debris, and so on, through various defense systems containing the immune system, the bacteria communicate with the local or distal tissues of the host via their own surface antigens, secreted products, nucleic acids, etc., resulting in relationships of attack and defense, adaptation, symbiosis, and even collaboration. The significance of bacterial membrane vesicles (MVs) as a powerful vehicle for the crosstalk mechanism between the two is growing. In the recent decade, the emergence of MVs in microbial interactions and a variety of bacterial infections, with multiple adhesions to host tissues, cell invasion and evasion of host defense mechanisms, have brought MVs to the forefront of bacterial pathogenesis research. Whereas MVs are a complex combination of molecules not yet fully understood, research into its effects, targeting and pathogenic components will advance its understanding and utilization. This review will summarize structural, extraction and penetration information on several classes of MVs and emphasize the role of MVs in transport and immune response activation. Finally, the potential of MVs as a therapeutic method will be highlighted, as will future research prospects.

Field-Flow Fractionation in Molecular Biology and Biotechnology

Field-flow fractionation (FFF) is a family of single-phase separative techniques exploited to gently separate and characterize nano- and microsystems in suspension. These techniques cover an extremely wide dynamic range and are able to separate analytes in an interval between a few nm to 100 µm size-wise (over 15 orders of magnitude mass-wise). They are flexible in terms of mobile phase and can separate the analytes in native conditions, preserving their original structures/properties as much as possible. Molecular biology is the branch of biology that studies the molecular basis of biological activity, while biotechnology deals with the technological applications of biology. The areas where biotechnologies are required include industrial, agri-food, environmental, and pharmaceutical. Many species of biological interest belong to the operational range of FFF techniques, and their application to the analysis of such samples has steadily grown in the last 30 years. This work aims to summarize the main features, milestones, and results provided by the application of FFF in the field of molecular biology and biotechnology, with a focus on the years from 2000 to 2022. After a theoretical background overview of FFF and its methodologies, the results are reported based on the nature of the samples analyzed.

Parallel SPR and QCM-D Quantitative Analysis of CD9, CD63, and CD81 Tetraspanins: A Simple and Sensitive Way to Determine the Concentration of Extracellular Vesicles Isolated from Human Lung Cancer Cells

Tetraspanins, including CD9, CD63, and CD81, are transmembrane biomarkers that play a crucial role in regulating cancer cell proliferation, invasion, and metastasis, as well as plasma membrane dynamics and protein trafficking. In this study, we developed simple, fast, and sensitive immunosensors to determine the concentration of extracellular vesicles (EVs) isolated from human lung cancer cells using tetraspanins as biomarkers. We employed surface plasmon resonance (SPR) and quartz crystal microbalance with dissipation (QCM-D) as detectors. The monoclonal antibodies targeting CD9, CD63, and CD81 were oriented vertically in the receptor layer using either a protein A sensor chip (SPR) or a cysteamine layer that modified the gold crystal (QCM-D) without the use of amplifiers. The SPR studies demonstrated that the interaction of EVs with antibodies could be described by the two-state reaction model. Furthermore, the EVs' affinity to monoclonal antibodies against tetraspanins decreased in the following order: CD9, CD63, and CD81, as confirmed by the QCM-D studies. The results indicated that the developed immunosensors were characterized by high stability, a wide analytical range from 6.1 × 10⁴ particles·mL^-1 to 6.1 × 10⁷ particles·mL^-1, and a low detection limit (0.6-1.8) × 10⁴ particles·mL^-1. A very good agreement between the results obtained using the SPR and QCM-D detectors and nanoparticle tracking analysis demonstrated that the developed immunosensors could be successfully applied to clinical samples.

The Role of Extracellular Vesicles in the Pathogenesis of Hematological Malignancies: Interaction with Tumor Microenvironment; a Potential Biomarker and Targeted Therapy

The tumor microenvironment (TME) plays an important role in the development and progression of hematological malignancies. In recent years, studies have focused on understanding how tumor cells communicate within the TME. In addition to several factors, such as growth factors, cytokines, extracellular matrix (ECM) molecules, etc., a growing body of evidence has indicated that extracellular vesicles (EVs) play a crucial role in the communication of tumor cells within the TME, thereby contributing to the pathogenesis of hematological malignancies. The present review focuses on how EVs derived from tumor cells interact with the cells in the TME, such as immune cells, stromal cells, endothelial cells, and ECM components, and vice versa, in the context of various hematological malignancies. EVs recovered from the body fluids of cancer patients often carry the bioactive molecules of the originating cells and hence can be considered new predictive biomarkers for specific types of cancer, thereby also acting as potential therapeutic targets. Here, we discuss how EVs influence hematological tumor progression via tumor-host crosstalk and their use as biomarkers for hematological malignancies, thereby benefiting the development of potential therapeutic targets.

The Power of Field-Flow Fractionation in Characterization of Nanoparticles in Drug Delivery

Asymmetric-flow field-flow fractionation (AF4) is a gentle, flexible, and powerful separation technique that is widely utilized for fractionating nanometer-sized analytes, which extend to many emerging nanocarriers for drug delivery, including lipid-, virus-, and polymer-based nanoparticles. To ascertain quality attributes and suitability of these nanostructures as drug delivery systems, including particle size distributions, shape, morphology, composition, and stability, it is imperative that comprehensive analytical tools be used to characterize the native properties of these nanoparticles. The capacity for AF4 to be readily coupled to multiple online detectors (MD-AF4) or non-destructively fractionated and analyzed offline make this technique broadly compatible with a multitude of characterization strategies, which can provide insight on size, mass, shape, dispersity, and many other critical quality attributes. This review will critically investigate MD-AF4 reports for characterizing nanoparticles in drug delivery, especially those reported in the last 10-15 years that characterize multiple attributes simultaneously downstream from fractionation.

A novel method for the direct detection of light stabilizer Tinuvin 622 in polymer additives by gel permeation chromatography combined with multi-angle laser light scattering

Tinuvin 622, an oligomeric light stabilizer, is widely used in plastics to reduce light and heat induced degradation and extend their service life, therefore its detection is of great importance for quality control of plastic products. However, the classical analytical methods of Tinuvin 622, such as chromatography and mass spectrometry, are difficult to achieve direct qualitative and quantitative analysis, and simultaneously to obtain the molecular weight and molecular weight distribution information. Herein, we propose for the first time the combination of gel permeation chromatography with multi-angle laser light scattering as a simple and direct method to detect Tinuvin 622 in polymers and simultaneously to obtain its molecular weight distribution information. The linearity of the method was good in the concentration range of 0.1-5.0 mg/mL Tinuvin 622 with correlation coefficient (R² = 0.9999), and the recoveries of Tinuvin 622 at three addition levels ranged from 94.0% to 98.7%, with relative standard deviations of no more than 1.73%. The proposed method has been successfully used to detect Tinuvin 622 in actual samples of polymer additives. Compared with existing analytical methods, Tinuvin 622 has a single peak shape in our method, which is easy to identify and quantify accurately; more importantly, our method can simultaneously characterize the molecular weight and molecular weight distribution of Tinuvin 622, which makes up for the shortcomings of other approaches and provides a new tool for quality monitoring of polymer additives.

Nanostructured-Based Optical Readouts Interfaced with Machine Learning for Identification of Extracellular Vesicles

Extracellular vesicles (EVs) are shed from cancer cells into body fluids, enclosing molecular information about the underlying disease with the potential for being the target cancer biomarker in emerging diagnosis approaches such as liquid biopsy. Still, the study of EVs presents major challenges due to their heterogeneity, complexity, and scarcity. Recently, liquid biopsy platforms have allowed the study of tumor-derived materials, holding great promise for early-stage diagnosis and monitoring of cancer when interfaced with novel adaptations of optical readouts and advanced machine learning analysis. Here, recent advances in labeled and label-free optical techniques such as fluorescence, plasmonic, and chromogenic-based systems interfaced with nanostructured sensors like nanoparticles, nanoholes, and nanowires, and diverse machine learning analyses are reviewed. The adaptability of the different optical methods discussed is compared and insights are provided into prospective avenues for the translation of the technological approaches for cancer diagnosis. It is discussed that the inherent augmented properties of nanostructures enhance the sensitivity of the detection of EVs. It is concluded by reviewing recent integrations of nanostructured-based optical readouts with diverse machine learning models as novel analysis ventures that can potentially increase the capability of the methods to the point of translation into diagnostic applications.

Recent developments in isolating methods for exosomes

Exosomes are the smallest extracellular vesicles that can be released by practically all cell types, and range in size from 30 nm to 150 nm. As the major marker of liquid biopsies, exosomes have great potential for disease diagnosis, therapy, and prognosis. However, their inherent heterogeneity, the complexity of biological fluids, and the presence of nanoscale contaminants make the isolation of exosomes a great challenge. Traditional isolation methods of exosomes are cumbersome and challenging with complex and time-consuming operations. In recent years, the emergence of microfluidic chips, nanolithography, electro-deposition, and other technologies has promoted the combination and innovation of the isolation methods. The application of these methods has brought very considerable benefits to the isolation of exosomes such as ultra-fast, portable integration, and low loss. There are significant functional improvements in isolation yield, isolation purity, and clinical applications. In this review, a series of methods for the isolation of exosomes are summarized, with emphasis on the emerging methods, and in-depth comparison and analysis of each method are provided, including their principles, merits, and demerits.

Offline Coupling of Asymmetrical Flow Field-Flow Fractionation and Capillary Electrophoresis for Separation of Extracellular Vesicles

Extracellular vesicles (EVs) play important roles in cell-to-cell communications and carry high potential as markers targeted in disease diagnosis, prognosis, and therapeutic development. The main obstacles to EV study are their high heterogeneity; low amounts present in samples; and physical similarity to the abundant, interfering matrix components. Multiple rounds of separation and purification are often needed prior to EV characterization and function assessment. Herein, we report the offline coupling of asymmetrical flow field-flow fractionation (AF4) and capillary electrophoresis (CE) for EV analysis. While AF4 provides gentle and fast EV separation by size, CE resolves EVs from contaminants with similar sizes but different surface charges. Employing Western Blotting, ELISA, and SEM, we confirmed that intact EVs were eluted within a stable time window under the optimal AF4 and CE conditions. We also proved that EVs could be resolved from free proteins and high-density lipoproteins by AF4 and be further separated from the low-density lipoproteins co-eluted in AF4. The effectiveness of the coupled AF4-CE system in EV analysis was demonstrated by monitoring the changes in EV secretion from cells and by direct injection of human serum and detection of serum EVs. We believe that coupling AF4 and CE can provide rapid EV quantification in biological samples with much reduced matrix interference and be valuable for the study of total EVs and EV subpopulations produced by cells or present in clinical samples.