Single-EV analysis (sEVA) of mutated proteins allows detection of stage 1 pancreatic cancer

Bridging laboratory innovation to translational research and commercialization of extracellular vesicle isolation and detection

Extracellular vesicles (EVs) have emerged as promising biomarkers for various diseases. Encapsulating biomolecules reflective of their parental cells, EVs are readily accessible in bodily fluids. The prospect for minimally invasive, repeatable molecular testing has stimulated significant research; however, challenges persist in isolating EVs from complex biological matrices and characterizing their limited molecular cargo. Technical advances have been pursued to address these challenges, producing innovative EV-specific platforms. This review highlights recent technological developments, focusing on EV isolation and molecular detection methodologies. Furthermore, it explores the translation of these laboratory innovations to clinical applications through the analysis of patient samples, providing insights into the potential diagnostic and prognostic utility of EV-based technologies.

Recent advances in dynamic single-molecule analysis platforms for diagnostics: Advantages over bulk assays and miniaturization approaches

Single-molecule science is a unique technique for unraveling molecular biophysical processes. Sensitivity to single molecules provides the capacity for the early diagnosis of low biomarker amounts. Furthermore, the miniaturization of instruments for portable diagnostic tools toward point-of-care testing (POCT) is a crucial development in this field. Herein, we discuss recent developments in single-molecule sensing platforms and their advantages for diagnostics over bulk measurements including molecular size measurements, interaction dynamics, and fast biomarker sensing and sequencing at low concentrations. We highlight the capabilities of dynamic optical and electrical sensing platforms for single-biomolecule and single-vesicle monitoring associated with neurodegenerative disorders, viral diseases, cancers, and more. Current approaches to instrument miniaturization have brought technology closer to portable diagnostics settings via smartphone-based devices, multifunctional portable microscopes, handheld electrical circuit devices, and remote single-molecule assays. Finally, we provide an overview of the clinical applications of single-molecule sensors in POCT assays. Altogether, single-molecule analyses platforms exhibit significant potential for the development of novel portable healthcare devices.

Decoding Complex Biological Milieus: SHINER's Approach to Profiling and Functioning of Extracellular Vesicle Subpopulations

Extracellular vesicles (EVs) are celebrated for their pivotal roles in cellular communication and their potential in disease diagnosis and therapeutic applications. However, their inherent heterogeneity acts as a double-edged sword, complicating the isolation of specific EV subpopulations. Conventional EV isolation methods often fall short, relying on biophysical properties, while affinity-based techniques may compromise EV integrity and utility with harsh recovery conditions. To address these limitations, the SHINER (subpopulation homogeneous isolation and nondestructive EV release) workflow is introduced, which redefines how EVs are isolated and recoverd, featuring the innovative SWITCHER (switchable extracellular vesicle releaser) tool. The SHINER workflow facilitates the precise purification and gentle recovery of target EV subpopulations from complex biological mixtures, preserving their structural integrity and biological functionality. Importantly, SHINER demonstrates exceptional adaptability to multiple markers and clinical applications. It not only enhances the ability to trace EV origins for accurate disease diagnosis but also advances fundamental EV research and provides standardized EV materials for therapeutic innovations. By improving the understanding of EVs and enabling the development of personalized diagnostics and treatments, SHINER propels EV-based science into new frontiers of advanced medicine, offering transformative potential for healthcare.

Human Differentiated Adipocytes as Surrogate Mature Adipocytes for Adipocyte-Derived Extracellular Vesicle Analysis

Obesity is a growing global health concern, contributing to diseases such as cancer, autoimmune disorders, and neurodegenerative conditions. Adipose tissue dysfunction, characterized by abnormal adipokine secretion and chronic inflammation, plays a key role in these conditions. Adipose-derived extracellular vesicles (ADEVs) have emerged as critical mediators in obesity-related diseases. However, the study of mature adipocyte-derived EVs (mAdipo-EVs) is limited due to the short lifespan of mature adipocytes in culture, low EV yields, and the low abundance of these EV subpopulations in the circulation. Additionally, most studies rely on rodent models, which have differences in adipose tissue biology compared to humans. To overcome these challenges, we developed a standardized approach for differentiating human preadipocytes (preAdipos) into mature differentiated adipocytes (difAdipos), which produce high-yield, human adipocyte EVs (Adipo-EVs). Using visceral adipose tissue from bariatric surgical patients, we isolated the stromal vascular fraction (SVF) and differentiated preAdipos into difAdipos. Brightfield microscopy revealed that difAdipos exhibited morphological characteristics comparable to mature adipocytes (mAdipos) directly isolated from visceral adipose tissue, confirming their structural similarity. Additionally, qPCR analysis demonstrated decreased preadipocyte markers and increased mature adipocyte markers, further validating successful differentiation. Functionally, difAdipos exhibited lipolytic activity comparable to mAdipos, supporting their functional resemblance to native adipocytes. We then isolated preAdipo-EVs and difAdipo-EVs using tangential flow filtration and characterized them using bulk and single EV analysis. DifAdipo-EVs displayed classical EV and adipocyte-specific markers, with significant differences in biomarker expression compared to preAdipo-EVs. These findings demonstrate that difAdipos serve as a reliable surrogate for mature adipocytes, offering a consistent and scalable source of adipocyte-derived EVs for studying obesity and its associated disorders.

Novel PPT+SEC Workflow for High-Sensitivity Extracellular Vesicle Proteomics from Cell Media

Size exclusion chromatography (SEC) is a well-established method for the isolation of extracellular vesicles (EVs), but the large elution volumes necessitate a concentration step prior to proteomics analysis. This concentration step can lead to a significant EV loss. Here we report an EV proteomics approach that enables the isolation of EVs into just 80 μL, which is directly compatible with proteomics analysis without the need for a prior concentration. EVs were characterized by transmission electron microscopy, Western blot, and nanoparticle tracking analysis, all of which confirmed the presence of small EVs. Proteomics analysis of the EVs was performed and benchmarked against those isolated by using an automated UHPLC-SEC platform. The novel workflow identified more proteins and more EV markers, including 96 of the 100 top exosomal proteins from the ExoCarta database, compared to 91 identified using EV samples isolated by UHPLC-SEC. When applied to EVs isolated from pancreatic cancer cell lines, the workflow demonstrated higher sensitivity for previously reported EV markers of pancreatic cancer.

Human differentiated adipocytes can serve as surrogate mature adipocytes for adipocyte-derived extracellular vesicle analysis

Obesity is a growing global health concern, contributing to diseases such as cancer, autoimmune disorders, and neurodegenerative conditions. Adipose tissue dysfunction, characterized by abnormal adipokine secretion and chronic inflammation, plays a key role in these conditions. Adipose-derived extracellular vesicles (ADEVs) have emerged as critical mediators in obesity-related diseases. However, the study of mature adipocyte-derived EVs (mAdipo-EVs) is limited due to the short lifespan of mature adipocytes in culture, low EV yields, and the low abundance of these EV subpopulations in the circulation. Additionally, most studies rely on rodent models, which have differences in adipose tissue biology compared to humans. To overcome these challenges, we developed a standardized approach for differentiating human preadipocytes (preAdipos) into mature differentiated adipocytes (difAdipos), which produce high-yield, human adipocyte EVs (Adipo-EVs). Using visceral adipose tissue from bariatric surgical patients, we isolated the stromal vascular fraction (SVF) and differentiated preAdipos into difAdipos. Brightfield microscopy revealed that difAdipos exhibited morphological characteristics comparable to mature adipocytes (mAdipos) directly isolated from visceral adipose tissue, confirming their structural similarity. Additionally, qPCR analysis demonstrated decreased preadipocyte markers and increased mature adipocyte markers, further validating successful differentiation. Functionally, difAdipos exhibited lipolytic activity comparable to mAdipos, supporting their functional resemblance to native adipocytes. We then isolated preAdipo-EVs and difAdipo-EVs using tangential flow filtration and characterized them using bulk and single EV analysis. DifAdipo-EVs displayed classical EV and adipocyte-specific markers, with significant differences in biomarker expression compared to preAdipo-EVs. These findings demonstrate that difAdipos serve as a reliable surrogate for mature adipocytes, offering a consistent and scalable source of adipocyte-derived EVs for studying obesity and its associated disorders. Keywords: extracellular vesicles, adipocyte, adipose, adipocyte-derived extracellular vesicles, obesity.

A Mem-dELISA platform for dual color and ultrasensitive digital detection of colocalized proteins on extracellular vesicles

Accurate, multiplex, and ultrasensitive measurement of different colocalized protein markers on individual tumor-derived extracellular vesicles (EVs) and dimerized proteins with multiple epitopes could provide insights into cancer heterogeneity, therapy management and early diagnostics that cannot be extracted from bulk methods. However, current digital protein assays lack certain features to enable robust colocalization, including multi-color detection capability, large dynamic range, and selectivity against background proteins. Here, we report a lithography-free, inexpensive (< $0.1) and ultrasensitive dual-color Membrane Digital ELISA (Mem-dELISA) platform by using track-etched polycarbonate (PCTE) membranes to overcome these shortcomings. Their through-pores remove air bubbles through wicking before they are sealed on one side by adhesion to form microwells. Immunomagnetic bead-analyte complexes and substrate solution are then loaded into the microwells from the opposite side, with >80% loading efficiency, before sealing with oil. This enables duplex digital protein colorimetric assay with beta galactosidase and alkaline phosphatase enzymes. The platform achieves 5 logs of dynamic range with a limit of detection of 10 aM for both Biotinylated β-galactosidase (B-βG) and Biotin Alkaline Phosphatase Conjugated (B-ALP) proteins. We demonstrate its potential by showing that a higher dosage of paclitaxel suppresses EpCAM-positive EVs but not GPC-1 positive EVs from breast cancer cells, a decline in chemo-resistance that cannot be detected with Western blot analysis of cell lysate. The Mem-dELISA is poised to empower researchers to conduct ultrasensitive, high throughput protein colocalization studies for disease diagnostics, treatment monitoring and biomarker discovery.

Direct imaging with multidimensional labelling and high-content analysis allows quantitative categorization and characterizations of individual small extracellular vesicles and nanoparticles (sEVPs)

Small extracellular vesicles and nanoparticles (sEVPs) are cell-secreted entities with potential as diagnostic biomarkers and therapeutic vehicles. However, significant intrinsic sEVP heterogeneity impedes analysis and understanding of their composition and functions. We employ multidimensional fluorescent labelling on sEVPs, leveraging the robustness of a newly developed membrane probe-conjugated oligoelectrolytes (COEs), and conduct total internal reflection fluorescence (TIRF) microscopy on sEVP arrays. These arrays comprise single sEVPs anchored to a soft material functionalized surface with little bias. We then develop an enhanced algorithm for colocalization analysis of the multiple labels on individual sEVPs and perform deep profiling of particle content. We categorize sEVPs derived from the same cell type into seven distinct subpopulations-some vesicular whereas others non-vesicular, and we demonstrate that sEVPs from four cell types exhibit quantitatively distinguishable subpopulation distributions. Furthermore, we gain insights into specific particle features within each subpopulation, including CD63 counts, relative particle size, relative concentration of cargoes, and correlations among different cargoes. This high-content analysis reveals common cargo sorting features in sEVP subpopulations across different cell types and suggests new statistics within the sEVP inherent heterogeneity that could differentiate sEVPs from two types of cancer cells and two types of normal cells. Collectively, our study presents a robust single-sEVP characterization platform, combining high-content imaging with comprehensive analysis. This platform is poised to advance sEVP-based theranostic assays and facilitate exploration into disease-associated sEVP biogenesis and sEVP-mediated intercellular communication.

Recent Advances in Wash-Free Detection Methods of Extracellular Vesicles: A Mini Review

Extracellular vesicles (EVs) are emerging biomarkers in liquid biopsy that have gained increasing attention in disease diagnosis and prognosis monitoring. Most reported detection methods require the isolation of EVs from complex body liquids, often involving multiple washing steps to remove excess reagents and eliminate background interference. Nonetheless, these methods not only cause the loss of EVs but also result in poor repeatability and prolonged detection duration. The focus on wash-free detection methods is increasing due to the specific ability to avoid the removal of surplus reagents and, in some cases, even the isolation and purification of EVs. Viewing from different methodological perspectives, this review summarizes the recent advances in wash-free detection of EVs, containing aggregation induction, proximity sensing, allosteric probes, phase separation, Roman spectroscopy, field-effect transistor and microcantilever. The pros and cons of each detection strategy are impartially evaluated and this review concludes the prospects for future developments in this field.

Single extracellular vesicle research: From cell population to a single cell

Extracellular vesicles (EVs) are secreted by cells with a membrane structure and complex components such as DNA, RNA and proteins. These biomolecules play an important role in cell communication, cell proliferation, cell migration, vascularization, immune response and other physiological and pathological processes. Most current research on EVs focused on populations of EVs. Heterogeneity of EVs is neglected. Considering the heterogeneity of single EVs may offer critical molecular insights into cell-cell interactions, it is necessary to enhance our understanding about molecular characteristics from EVs derived from cell population to a single EV of derived from a single cell. This transformation is expected to provide a new insight into the understanding of cellular biology and the accurate description of the law of disease progress. In this article, we review the current research progress of single EV analysis technology for single EVs derived from cell population (SECP) and discuss its main applications in biological and clinical medicine research. After that, we propose the development direction, main difficulties and application prospect of single EV analysis technology for single EVs derived from single cells (SESC) according to our own research work, to provide new perspectives for the field of EV research.

Tracking Small Extracellular Vesicles Using a Minimally Invasive PicoGreen Labeling Strategy

Extracellular vesicles (EVs) are cell-secreted lipid bilayer delimited particles that mediate cellular communication. These tiny sacs of cellular information play an important role in cell communication and alter the physiological process under both normal and pathological conditions. As such, tracking EVs can provide valuable information regarding the basic understanding of cell communication, the onset of early malignancy, and biomarker discovery. Most of the current EV-tracking strategies are invasive, altering the natural characteristics of EVs by modifying the lipid bilayer with lipophilic dyes or surface proteins with fluorescent reporters. The invasive labeling strategies could alter the natural processes of EVs and thereby have major limitations for functional studies. Here, we report an alternative minimally invasive EV labeling strategy using PicoGreen (PG), a small molecule that fluoresces at 520 nm when bound to dsDNA. We show that PG binds to dsDNA associated with small EVs (50-200 nm), forming a stable and highly fluorescent PG-DNA complex in EVs (PG-EVs). In both 2D cell culture and 3D organoid models, PG-EV showed efficient tracking properties, including a high signal-to-noise ratio, time- and concentration-dependent uptake, and the ability to traverse a 3D environment. We further validated PG-EV tracking using dual-labeled EVs following two orthogonal labeling strategies: (1) Bioconjugation via surface amine labeling and (2) donor cell engineering via endogenously expressing mCherry-tetraspanin (CD9/CD63/CD81) reporter proteins. Our study has shown the feasibility of using PG-EV as an effective EV tracking strategy that can be applied for studying the functional role of EVs across multiple model systems.

Dynamic reorganization of multivesicular bodies and exosome production impacted by sonoporation

Naturally occurring cell-derived extracellular vesicles (EVs) have emerged as attractive nanocarriers for drug delivery. However, production of large quantities of EVs for clinical applications in a scalable manner remains a significant challenge. This study investigated at the single cell level how sonoporation, or membrane poration produced by ultrasound-induced microbubble cavitation, impacts EV production using mouse macrophage RAW 264.7 cells stably expressing CD63-GFP as a model system. Real-time fluorescence videomicroscopy detected rapid changes in CD63-GFP, a tetraspanin family member highly enriched in intraluminal vesicles tagged with GFP, to track changes in multivesicular bodies (MVBs), which are the cellular compartments where exosomes originate within the cells. Our results revealed distinct dynamic changes in CD63-GFP intensity and distribution in RAW 264.7 cells in terms of response time and duration depending on whether the cells were directly or indirectly impacted by sonoporation, suggesting reorganization of MVBs in response to direct and indirect mechanisms resulted from the mechanical impact of ultrasound pulse on the cells. Analysis of the supernatant from sonoporation-treated RAW 264.7 cells expressing CD63-GFP demonstrated a delayed and sustained increase in the production of CD63-GFP-positive EVs. These results show the robust and detailed effect of sonoporation and reveal insights into sonoporation-induced EV release useful for guiding the application of sonoporation to enhance large-scale EV production.

The new advance of exosome-based liquid biopsy for cancer diagnosis

Liquid biopsy is a minimally invasive method that uses biofluid samples instead of tissue samples for cancer diagnosis. Exosomes are small extracellular vesicles secreted by donor cells and act as mediators of intercellular communication in human health and disease. Due to their important roles, exosomes have been considered as promising biomarkers for liquid biopsy. However, traditional methods for exosome isolation and cargo detection methods are time-consuming and inefficient, limiting their practical application. In the past decades, many new strategies, such as microfluidic chips, nanowire arrays and electrochemical biosensors, have been proposed to achieve rapid, accurate and high-throughput detection and analysis of exosomes. In this review, we discussed about the new advance in exosome-based liquid biopsy technology, including isolation, enrichment, cargo detection and analysis approaches. The comparison of currently available methods is also included. Finally, we summarized the advantages and limitations of the present strategies and further gave a perspective to their future translational use.

Factors to consider before choosing EV labeling method for fluorescence-based techniques

A well-designed fluorescence-based analysis of extracellular vesicles (EV) can provide insights into the size, morphology, and biological function of EVs, which can be used in medical applications. Fluorescent nanoparticle tracking analysis with appropriate controls can provide reliable data for size and concentration measurements, while nanoscale flow cytometry is the most appropriate tool for characterizing molecular cargoes. Label selection is a crucial element in all fluorescence methods. The most comprehensive data can be obtained if several labeling approaches for a given marker are used, as they would provide complementary information about EV populations and interactions with the cells. In all EV-related experiments, the influence of lipoproteins and protein corona on the results should be considered. By reviewing and considering all the factors affecting EV labeling methods used in fluorescence-based techniques, we can assert that the data will provide as accurate as possible information about true EV biology and offer precise, clinically applicable information for future EV-based diagnostic or therapeutic applications.

Extracellular vesicles in cancer: challenges and opportunities for clinical laboratories

Extracellular vesicles (EVs) are nano-sized particles secreted by most cells. They transport different types of biomolecules (nucleic acids, proteins, and lipids) characteristic of their tissue or cellular origin that can mediate long-distance intercellular communication. In the case of cancer, EVs participate in tumor progression by modifying the tumor microenvironment, favoring immune tolerance and metastasis development. Consequently, EVs have great potential in liquid biopsy for cancer diagnosis, prognosis and follow-up. In addition, EVs could have a role in cancer treatment as a targeted drug delivery system. The intense research in the EV field has resulted in hundreds of patents and the creation of biomedical companies. However, methodological issues and heterogeneity in EV composition have hampered the advancement of EV validation trials and the development of EV-based diagnostic and therapeutic products. Consequently, only a few EV biomarkers have moved from research to clinical laboratories, such as the ExoDx Prostate IntelliScore (EPI) test, a CLIA/FDA-approved EV prostate cancer diagnostic test. In addition, the number of large-scale multicenter studies that would clearly define biomarker performance is limited. In this review, we will critically describe the different types of EVs, the methods for their enrichment and characterization, and their biological role in cancer. Then, we will specially focus on the parameters to be considered for the translation of EV biology to the clinic laboratory, the advances already made in the field of EVs related to cancer diagnosis and treatment, and the issues still pending to be solved before EVs could be used as a routine tool in oncology.

Deciphering extracellular vesicles protein cargo in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) presents a significant therapeutic challenge as it is frequently diagnosed at advanced inoperable stages. Therefore, the development of a reliable screening tool for PDAC is crucial for effective prevention and treatment. Extracellular vesicles (EVs), characterized by their cup-shaped lipid bilayer structure and ubiquitous release from various cell types, offer notable advantages as an emerging liquid biopsy technique that is rapid, minimally invasive, easily sampled, and cost-effective. While EVs play a substantial role in cancer progression, EV proteins serve as direct mediators of diverse cellular behaviors and have immense potential as biomarkers for PDAC diagnosis and prognostication. This review provides an overview of EV proteins regarding PDAC diagnosis and prognostic implications as well as disease progression.

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.

The systematic role of pancreatic cancer exosomes: distant communication, liquid biopsy and future therapy

Pancreatic cancer remains one of the most lethal diseases worldwide. Cancer-derived exosomes, benefiting from the protective role of the lipid membrane, exhibit remarkable stability in the circulatory system. These exosomes, released by tumor microenvironment, contain various biomolecules such as proteins, RNAs, and lipids that plays a pivotal role in mediating distant communication between the local pancreatic tumor and other organs or tissues. They facilitate the transfer of oncogenic factors to distant sites, contributing to the compromised body immune system, distant metastasis, diabetes, cachexia, and promoting a microenvironment conducive to tumor growth and metastasis in pancreatic cancer patients. Beyond their intrinsic roles, circulating exosomes in peripheral blood can be detected to facilitate accurate liquid biopsy. This approach offers a novel and promising method for the diagnosis and management of pancreatic cancer. Consequently, circulating exosomes are not only crucial mediators of systemic cell-cell communication during pancreatic cancer progression but also hold great potential as precise tools for pancreatic cancer management and treatment. Exosome-based liquid biopsy and therapy represent promising advancements in the diagnosis and treatment of pancreatic cancer. Exosomes can serve as drug delivery vehicles, enhancing the targeting and efficacy of anticancer treatments, modulating the immune system, and facilitating gene editing to suppress tumor growth. Ongoing research focuses on biomarker identification, drug delivery systems, and clinical trials to validate the safety and efficacy of exosome-based therapies, offering new possibilities for early diagnosis and precision treatment in pancreatic cancer. Leveraging the therapeutic potential of exosomes, including their ability to deliver targeted drugs and modulate immune responses, opens new avenues for innovative treatment strategies.

Before Translating Extracellular Vesicles into Personalized Diagnostics and Therapeutics: What We Could Do

Extracellular vesicle (EV) research is rapidly advancing from fundamental science to translational applications in EV-based personalized therapeutics and diagnostics. Yet, fundamental questions persist regarding EV biology and mechanisms, particularly concerning the heterogeneous interactions between EVs and cells. While we have made strides in understanding virus delivery and intracellular vesicle transport, our comprehension of EV trafficking remains limited. EVs are believed to mediate intercellular communication through cargo transfer, but uncertainties persist regarding the occurrence and quantification of EV-cargo delivery within acceptor cells. This ambiguity is crucial to address, given the significant translational impact of EVs on therapeutics and diagnostics. This perspective article does not seek to provide exhaustive recommendations and guidance on EV-related studies, as these are well-articulated in position papers and statements by the International Society for Extracellular Vesicles (ISEV), including the 'Minimum Information for Studies of Extracellular Vesicles' (MISEV) 2014, MISEV2018, and the recent MISEV2023. Instead, recognizing the multilayered heterogeneity of EVs as both a challenge and an opportunity, this perspective emphasizes novel approaches to facilitate our understanding of diverse EV biology, address uncertainties, and leverage this knowledge to advance EV-based personalized diagnostics and therapeutics. Specifically, this perspective synthesizes current insights, identifies opportunities, and highlights exciting technological advancements in ultrasensitive single EV or "digital" profiling developed within the author's multidisciplinary group. These newly developed technologies address technical gaps in dissecting the molecular contents of EV subsets, contributing to the evolution of EVs as next-generation liquid biopsies for diagnostics and providing better quality control for EV-based therapeutics.

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.

Extracellular vesicles in nanomedicine and regenerative medicine: A review over the last decade

Small extracellular vesicles (sEVs) are known to be secreted by a vast majority of cells. These sEVs, specifically exosomes, induce specific cell-to-cell interactions and can activate signaling pathways in recipient cells through fusion or interaction. These nanovesicles possess several desirable properties, making them ideal for regenerative medicine and nanomedicine applications. These properties include exceptional stability, biocompatibility, wide biodistribution, and minimal immunogenicity. However, the practical utilization of sEVs, particularly in clinical settings and at a large scale, is hindered by the expensive procedures required for their isolation, limited circulation lifetime, and suboptimal targeting capacity. Despite these challenges, sEVs have demonstrated a remarkable ability to accommodate various cargoes and have found extensive applications in the biomedical sciences. To overcome the limitations of sEVs and broaden their potential applications, researchers should strive to deepen their understanding of current isolation, loading, and characterization techniques. Additionally, acquiring fundamental knowledge about sEVs origins and employing state-of-the-art methodologies in nanomedicine and regenerative medicine can expand the sEVs research scope. This review provides a comprehensive overview of state-of-the-art exosome-based strategies in diverse nanomedicine domains, encompassing cancer therapy, immunotherapy, and biomarker applications. Furthermore, we emphasize the immense potential of exosomes in regenerative medicine.

A Panorama of Extracellular Vesicle Applications: From Biomarker Detection to Therapeutics

Extracellular vesicles (EVs) secreted by all cell types are involved in the cell-to-cell transfer of regulatory factors that influence cell and tissue phenotypes in normal and diseased tissues. EVs are thus a rich source of biomarker targets for assays that analyze blood and urinary EVs for disease diagnosis. Sensitive biomarker detection in EVs derived from specific cell populations is a key major hurdle when analyzing complex biological samples, but innovative approaches surveyed in this Perspective can streamline EV isolation and enhance the sensitivity of EV detection procedures required for clinical application of EV-based diagnostics and therapeutics, including nanotechnology and microfluidics, to achieve EV characterizations. Finally, this Perspective also outlines opportunities and challenges remaining for clinical translation of EV-based assays.

A Current Synopsis of the Emerging Role of Extracellular Vesicles and Micro-RNAs in Pancreatic Cancer: A Forward-Looking Plan for Diagnosis and Treatment

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest malignancies worldwide, while it persists as the fourth most prevalent cause of cancer-related death in the United States of America. Although there are several novel therapeutic strategies for the approach of this intensely aggressive tumor, it remains a clinical challenge, as it is hard to identify in early stages, due to its asymptomatic course. A diagnosis is usually established when the disease is already in its late stages, while its chemoresistance constitutes an obstacle to the optimal management of this malignancy. The discovery of novel diagnostic and therapeutic tools is considered a necessity for this tumor, due to its low survival rates and treatment failures. One of the most extensively investigated potential diagnostic and therapeutic modalities is extracellular vesicles (EVs). These vesicles constitute nanosized double-lipid membraned particles that are characterized by a high heterogeneity that emerges from their distinct biogenesis route, their multi-variable sizes, and the particular cargoes that are embedded into these particles. Their pivotal role in cell-to-cell communication via their cargo and their implication in the pathophysiology of several diseases, including pancreatic cancer, opens new horizons in the management of this malignancy. Meanwhile, the interplay between pancreatic carcinogenesis and short non-coding RNA molecules (micro-RNAs or miRs) is in the spotlight of current studies, as they can have either a role as tumor suppressors or promoters. The deregulation of both of the aforementioned molecules leads to several aberrations in the function of pancreatic cells, leading to carcinogenesis. In this review, we will explore the role of extracellular vesicles and miRNAs in pancreatic cancer, as well as their potent utilization as diagnostic and therapeutic tools.

Thermophoretic glycan profiling of extracellular vesicles for triple-negative breast cancer management

Triple-negative breast cancer (TNBC) is a highly metastatic and heterogeneous type of breast cancer with poor outcomes. Precise, non-invasive methods for diagnosis, monitoring and prognosis of TNBC are particularly challenging due to a paucity of TNBC biomarkers. Glycans on extracellular vesicles (EVs) hold the promise as valuable biomarkers, but conventional methods for glycan analysis are not feasible in clinical practice. Here, we report that a lectin-based thermophoretic assay (EVLET) streamlines vibrating membrane filtration (VMF) and thermophoretic amplification, allowing for rapid, sensitive, selective and cost-effective EV glycan profiling in TNBC plasma. A pilot cohort study shows that the EV glycan signature reaches 91% accuracy for TNBC detection and 96% accuracy for longitudinal monitoring of TNBC therapeutic response. Moreover, we demonstrate the potential of EV glycan signature for predicting TNBC progression. Our EVLET system lays the foundation for non-invasive cancer management by EV glycans.

[Early detection of sporadic pancreatic cancer]

The incidence of pancreatic cancer is rising. At present, pancreatic cancer is the third most common cancer-causing death in Germany, but it is expected to become the second in 2030 and finally the leading cause of cancer death in 2050. Pancreatic ductal adenocarcinoma (PC) is generally diagnosed at advanced stages, and 5-year-survival has remained poor. Early detection of sporadic PC at stage IA, however, can yield a 5-year-survival rate of about 80%. Early detection initiatives aim at identifying persons at high risk. People with new-onset diabetes at age 50 or older have attracted much interest. Novel strategies regarding how to detect sporadic PC at an early stage are being discussed.

Colocalization of protein and microRNA markers reveals unique extracellular vesicle subpopulations for early cancer detection

Extracellular vesicles (EVs) play important roles in cell-cell communication but are highly heterogeneous, and each vesicle has dimensions smaller than 200 nm with very limited amounts of cargos encapsulated. The technique of NanOstirBar (NOB)-EnabLed Single Particle Analysis (NOBEL-SPA) reported in the present work permits rapid inspection of single EV with high confidence by confocal fluorescence microscopy, thus enables colocalization assessment for selected protein and microRNA (miRNA) markers in the EVs produced by various cell lines, or present in clinical sera samples. EV subpopulations marked by the colocalization of unique protein and miRNA combinations were discovered to be able to detect early-stage (stage I or II) breast cancer (BC). NOBEL-SPA can be adapted to analyze other types of cargo molecules or other small submicron biological particles. Study of the sorting of specific cargos to heterogeneous vesicles under different physiological conditions can help discover distinct vesicle subpopulations valuable in clinical examination and therapeutics development and gain better understanding of their biogenesis.

Profiling DNA Cargos in Single Extracellular Vesicles via Hydrogel-Based Droplet Digital Multiple Displacement Amplification

Due to the substantial heterogeneity among extracellular vesicle (EV) subpopulations, single-EV analysis has the potential to elucidate the mechanisms behind EV biogenesis and shed light on the myriad functions, leading to the development of novel diagnostics and therapeutics. While many studies have been devoted to reveal between-EV variations in surface proteins and RNAs, DNA cargos (EV-DNA) have received little attention. Here, we report a hydrogel-based droplet digital multiple displacement amplification approach for the comprehensive analysis of EV-DNA at the single-EV level. Single EVs are dispersed in thousands of hydrogel droplets and lysed for DNA amplification and identification. The droplet microfluidics strategy empowers the assay with single-molecule sensitivity and capability for absolute quantification of DNA-containing EVs. In particular, our findings indicate that 5-40% EVs are associated with DNA, depending on the cell of origin. Large EVs exhibit a higher proportion of DNA-containing EVs and a more substantial presence of intraluminal DNA, compared to small EVs. These DNA-containing EVs carry multiple DNA fragments on average. Furthermore, both double-stranded DNA and single-stranded DNA were able to be detected at the single-EV level. Utilizing this method, the abundance, distribution, and biophysical properties of EV-DNA in various EV populations are evaluated. The DNA level within EVs provides insight into the status of the originating cells and offers valuable information on the outcomes of anticancer treatments. The utilization of single-EV analysis for EV-DNA holds significant promise for early cancer detection and treatment response monitoring.

Extracellular Vesicles as Liquid Biopsy Biomarkers across the Cancer Journey: From Early Detection to Recurrence

BACKGROUND

Cancer is a dynamic process and thus requires highly informative and reliable biomarkers to help guide patient care. Liquid-based biopsies have emerged as a clinical tool for tracking cancer dynamics. Extracellular vesicles (EVs), lipid bilayer delimited particles secreted by cells, are a new class of liquid-based biomarkers. EVs are rich in selectively sorted biomolecule cargos, which provide a spatiotemporal fingerprint of the cell of origin, including cancer cells.

CONTENT

This review summarizes the performance characteristics of EV-based biomarkers at different stages of cancer progression, from early malignancy to recurrence, while emphasizing their potential as diagnostic, prognostic, and screening biomarkers. We discuss the characteristics of effective biomarkers, consider challenges associated with the EV biomarker field, and report guidelines based on the biomarker discovery pipeline.

SUMMARY

Basic science and clinical trial studies have shown the potential of EVs as precision-based biomarkers for tracking cancer status, with promising applications for diagnosing disease, predicting response to therapy, and tracking disease burden. The multi-analyte cargos of EVs enhance the performance characteristics of biomarkers. Recent technological advances in ultrasensitive detection of EVs have shown promise with high specificity and sensitivity to differentiate early-cancer cases vs healthy individuals, potentially outperforming current gold-standard imaging-based cancer diagnosis. Ultimately, clinical translation will be dictated by how these new EV biomarker-based platforms perform in larger sample cohorts. Applying ultrasensitive, scalable, and reproducible EV detection platforms with better design considerations based upon the biomarker discovery pipeline should guide the field towards clinically useful liquid biopsy biomarkers.

Ultrasensitive and High-Resolution Protein Spatially Decoding Framework for Tumor Extracellular Vesicles

Proteins localized on the surface or within the lumen of tumor-derived extracellular vesicles (EVs) play distinct roles in cancer progression. However, quantifying both populations of proteins within EVs has been hampered due to the limited sensitivity of the existing protein detection methods and inefficient EV isolation techniques. In this study, the eSimoa framework, an innovative approach enabling spatial decoding of EV protein biomarkers with unmatched sensitivity and specificity is presented. Using the luminal eSimoa pipeline, the absolute concentration of luminal RAS or KRASG12D proteins is released and measured, uncovering their prevalence in pancreatic tumor-derived EVs. The pulldown eSimoa pipeline measured absolute protein concentrations from low-abundance EV subpopulations. The eSimoa assays detected EVs in both PBS and plasma samples, confirming their applicability across diverse clinical sample types. Overall, the eSimoa framework offers a valuable tool to (1) detect EVs at concentrations as low as 105 EV mL-1 in plasma, (2) quantify absolute EV protein concentrations as low as fM, and (3) decode the spatial distribution of EV proteins. This study highlights the potential of eSimoa in identifying disease-specific EV protein biomarkers in clinical samples with minimal pre-purification, thereby driving advancements in clinical translation.

Exosomes: Potential key players towards novel therapeutic options in diabetic wounds

Diabetic wounds are usually difficult to heal, and wounds in foot in particular are often aggravated by infection, trauma, diabetic neuropathy, peripheral vascular disease and other factors, resulting in serious foot ulcers. The pathogenesis and clinical manifestations of diabetic wounds are complicated, and there is still a lack of objective and in-depth laboratory diagnosis and classification standards. Exosomes are nanoscale vesicles containing DNA, mRNA, microRNA, cyclic RNA, metabolites, lipids, cytoplasm and cell surface proteins, etc., which are involved in intercellular communication and play a crucial role in vascular regeneration, tissue repair and inflammation regulation in the process of diabetic wound healing. Here, we discussed exosomes of different cellular origins, such as diabetic wound-related fibroblasts (DWAF), adipose stem cells (ASCs), mesenchymal stem cells (MSCs), immune cells, platelets, human amniotic epithelial cells (hAECs), epidermal stem cells (ESCs), and their various molecular components. They exhibit multiple therapeutic effects during diabetic wound healing, including promoting cell proliferation and migration associated with wound healing, regulating macrophage polarization to inhibit inflammatory responses, promoting nerve repair, and promoting vascular renewal and accelerating wound vascularization. In addition, exosomes can be designed to deliver different therapeutic loads and have the ability to deliver them to the desired target. Therefore, exosomes may become an innovative target for precision therapeutics in diabetic wounds. In this review, we summarize the latest research on the role of exosomes in the healing of diabetic wound by regulating the pathogenesis of diabetic wounds, and discuss their potential applications in the precision treatment of diabetic wounds.

Seminar: Extracellular Vesicles as Mediators of Environmental Stress in Human Disease

BACKGROUND

Extracellular vesicles (EVs), membrane-bound particles containing a variety of RNA types, DNA, proteins, and other macromolecules, are now appreciated as an important means of communication between cells and tissues, both in normal cellular physiology and as a potential indicator of cellular stress, environmental exposures, and early disease pathogenesis. Extracellular signaling through EVs is a growing field of research for understanding fundamental mechanisms of health and disease and for the potential for biomarker discovery and therapy development. EVs are also known to play important roles in mediating the effects of exposure to environmental stress.

OBJECTIVES

This seminar addresses the application of new tools and approaches for EV research, developed in part through the National Institutes of Health (NIH) Extracellular RNA Communication Program, and reflects presentations and discussions from a workshop held 27-28 September 2021 by the National Institute of Environmental Health Sciences (NIEHS) and the National Center for Advancing Translational Sciences (NCATS) on "Extracellular Vesicles, Exosomes, and Cell-Cell Signaling in Response to Environmental Stress." The panel of experts discussed current research on EVs and environmental exposures, highlighted recent advances in EV isolation and characterization, and considered research gaps and opportunities toward identifying and characterizing the roles for EVs in environmentally related diseases, as well as the current challenges and opportunities in this field.

DISCUSSION

The authors discuss the application of new experimental models, particularly organ-on-chip (OOC) systems and in vitro approaches and how these have the potential to extend findings in population-based studies of EVs in exposure-related diseases. Given the complex challenges of identifying cell-specific EVs related to environmental exposures, as well as the general heterogeneity and variability in EVs in blood and other accessible biological samples, there is a critical need for rigorous reporting of experimental methods and validation studies. The authors note that these efforts, combined with cross-disciplinary approaches, would ensure that future research efforts in environmental health studies on EV biomarkers are rigorous and reproducible. https://doi.org/10.1289/EHP12980.

Extracellular Vesicles: Techniques and Biomedical Applications Related to Single Vesicle Analysis

Extracellular vesicles (EVs) are extensively dispersed lipid bilayer membrane vesicles involved in the delivery and transportation of molecular payloads to certain cell types to facilitate intercellular interactions. Their significant roles in physiological and pathological processes make EVs outstanding biomarkers for disease diagnosis and treatment monitoring as well as ideal candidates for drug delivery. Nevertheless, differences in the biogenesis processes among EV subpopulations have led to a diversity of biophysical characteristics and molecular cargos. Additionally, the prevalent heterogeneity of EVs has been found to substantially hamper the sensitivity and accuracy of disease diagnosis and therapeutic monitoring, thus impeding the advancement of clinical applications. In recent years, the evolution of single EV (SEV) analysis has enabled an in-depth comprehension of the physical properties, molecular composition, and biological roles of EVs at the individual vesicle level. This review examines the sample acquisition tactics prior to SEV analysis, i.e., EV isolation techniques, and outlines the current state-of-the-art label-free and label-based technologies for SEV identification. Furthermore, the challenges and prospects of biomedical applications based on SEV analysis are systematically discussed.

ATP1A3 as a target for isolating neuron-specific extracellular vesicles from human brain and biofluids

Neuron-derived extracellular vesicles (NDEVs) are potential biomarkers of neurological diseases although their reliable molecular target is not well established. Here, we demonstrate that ATPase Na+/K+ transporting subunit alpha 3 (ATP1A3) is abundantly expressed in extracellular vesicles (EVs) isolated from induced human neuron, brain, cerebrospinal fluid, and plasma in comparison with the presumed NDEV markers NCAM1 and L1CAM by using super-resolution microscopy and biochemical assessments. Proteomic analysis of immunoprecipitated ATP1A3+ brain-derived EVs shows higher enrichment of synaptic markers and cargo proteins relevant to Alzheimer's disease (AD) compared to NCAM1+ or LICAM+ EVs. Single particle analysis shows the elevated amyloid-β positivity in ATP1A3+ EVs from AD plasma, providing better diagnostic prediction of AD over other plasma biomarkers. Thus, ATP1A3 is a reliable target to isolate NDEV from biofluids for diagnostic research.

Precise Identification and Profiling of Surface Proteins of Ultra Rare Tumor Specific Extracellular Vesicle with Dynamic Quantitative Plasmonic Imaging

Specific detection of tumor-derived EVs (tEVs) in plasma is complicated by nontumor EVs and non-EV particles. To accurately identify tEVs and profile their surface protein expression at single tEV resolution directly with clinical plasma is still an unmet need. Here, we present a Dynamic Immunoassay for Single tEV surface protein Profiling (DISEP), a kinetic assay based on surface plasmon resonance microscopy (SPRM) for specific single tEV profiling. DISEP adopts a pair of low-affinity oligonucleotide probes to respectively label EV surface proteins and functionalize an SPRM biosensor interface. tEVs labeled with the oligonucleotide probes possess distinctive binding kinetics from nonspecific particles in plasma, which permits accurate digital plasmonic counting of single EVs. We demonstrate DISEP for recognizing target EVs among 350-fold background plasma particles with high sensitivity (4677 EVs per μL). Clinical plasma samples were analyzed to discriminate between pancreatic cancer patients (n = 40) and healthy donors (n = 45). With a panel of biomarker signatures (EpCAM, HER2, and GPC1), DISEP only requires 10 μL primary sample from each donor to classify tumor patients with an area under the curve of 0.98. DISEP provides a highly specific EV detection and surface protein profiling strategy for early cancer diagnosis.

CRISPR/Cas13a-Based MicroRNA Detection in Tumor-Derived Extracellular Vesicles

MicroRNAs (miRNAs) in extracellular vesicles (EVs) play essential roles in cancer initiation and progression. Quantitative measurements of EV miRNAs are critical for cancer diagnosis and longitudinal monitoring. Traditional PCR-based methods, however, require multi-step procedures and remain as bulk analysis. Here, the authors introduce an amplification-free and extraction-free EV miRNA detection method using a CRISPR/Cas13a sensing system. CRISPR/Cas13a sensing components are encapsulated in liposomes and delivered them into EVs through liposome-EV fusion. This allows for accurately quantify specific miRNA-positive EV counts using 1 × 108  EVs. The authors show that miR-21-5p-positive EV counts are in the range of 2%-10% in ovarian cancer EVs, which is significantly higher than the positive EV counts from the benign cells (<0.65%). The result show an excellent correlation between bulk analysis with the gold-standard method, RT-qPCR. The authors also demonstrate multiplexed protein-miRNA analysis in tumor-derived EVs by capturing EpCAM-positive EVs and quantifying miR-21-5p-positive ones in the subpopulation, which show significantly higher counts in the plasma of cancer patients than healthy controls. The developed EV miRNA sensing system provides the specific miRNA detection method in intact EVs without RNA extraction and opens up the possibility of multiplexed single EV analysis for protein and RNA markers.

Extracellular vesicle analysis of plasma allows differential diagnosis of atypical pancreatic serous cystadenoma

Increased use of cross-sectional imaging has resulted in frequent detection of incidental cystic pancreatic lesions. Serous cystadenomas (SCAs) are benign cysts that do not require surgical intervention unless symptomatic. Unfortunately, up to half of SCAs do not have typical imaging findings ("atypical SCAs"), overlap with potentially malignant precursor lesions, and thus pose a diagnostic challenge. We tested whether the analysis of circulating extracellular vesicle (EV) biomarkers using a digital EV screening technology (DEST) could enhance the discrimination of cystic pancreatic lesions and avoid unnecessary surgical intervention in these atypical SCAs. Analysis of 25 different protein biomarkers in plasma EV from 68 patients identified a putative biomarker signature of Das-1, Vimentin, Chromogranin A, and CAIX with high discriminatory power (AUC of 0.99). Analysis of plasma EV for multiplexed markers may thus be helpful in clinical decision-making.

Single Extracellular VEsicle Nanoscopy

Extracellular vesicles (EVs) and their cargo constitute novel biomarkers. EV subpopulations have been defined not only by abundant tetraspanins (e.g., CD9, CD63 and CD81) but also by specific markers derived from their source cells. However, it remains a challenge to robustly isolate and characterize EV subpopulations. Here, we combined affinity isolation with super-resolution imaging to comprehensively assess EV subpopulations from human plasma. Our Single Extracellular VEsicle Nanoscopy (SEVEN) assay successfully quantified the number of affinity-isolated EVs, their size, shape, molecular tetraspanin content, and heterogeneity. The number of detected tetraspanin-enriched EVs positively correlated with sample dilution in a 64-fold range (for SEC-enriched plasma) and a 50-fold range (for crude plasma). Importantly, SEVEN robustly detected EVs from as little as ∼0.1 μL of crude plasma. We further characterized the size, shape and molecular tetraspanin content (with corresponding heterogeneities) for CD9-, CD63- and CD81-enriched EV subpopulations. Finally, we assessed EVs from the plasma of four pancreatic ductal adenocarcinoma patients with resectable disease. Compared to healthy plasma, CD9-enriched EVs from patients were smaller while IGF1R-enriched EVs from patients were larger, rounder and contained more tetraspanin molecules, suggestive of a unique pancreatic cancer-enriched EV subpopulation. This study provides the method validation and demonstrates that SEVEN could be advanced into a platform for characterizing both disease-associated and organ-associated EV subpopulations.

MoS2-Plasmonic Nanocavities for Raman Spectra of Single Extracellular Vesicles Reveal Molecular Progression in Glioblastoma

Extracellular vesicles (EVs) are continually released from cancer cells into biofluids, carrying actionable molecular fingerprints of the underlying disease with considerable diagnostic and therapeutic potential. The scarcity, heterogeneity and intrinsic complexity of tumor EVs present a major technological challenge in real-time monitoring of complex cancers such as glioblastoma (GBM). Surface-enhanced Raman spectroscopy (SERS) outputs a label-free spectroscopic fingerprint for EV molecular profiling. However, it has not been exploited to detect known biomarkers at the single EV level. We developed a multiplex fluidic device with embedded arrayed nanocavity microchips (MoSERS microchip) that achieves 97% confinement of single EVs in a minute amount of fluid (<10 μL) and enables molecular profiling of single EVs with SERS. The nanocavity arrays combine two featuring characteristics: (1) An embedded MoS₂ monolayer that enables label-free isolation and nanoconfinement of single EVs due to physical interaction (Coulomb and van der Waals) between the MoS₂ edge sites and the lipid bilayer; and (2) A layered plasmonic cavity that enables sufficient electromagnetic field enhancement inside the cavities to obtain a single EV level signal resolution for stratifying the molecular alterations. We used the GBM paradigm to demonstrate the diagnostic potential of the SERS single EV molecular profiling approach. The MoSERS multiplexing fluidic achieves parallel signal acquisition of glioma molecular variants (EGFRvIII oncogenic mutation and MGMT expression) in GBM cells. The detection limit of 1.23% was found for stratifying these key molecular variants in the wild-type population. When interfaced with a convolutional neural network (CNN), MoSERS improved diagnostic accuracy (87%) with which GBM mutations were detected in 12 patient blood samples, on par with clinical pathology tests. Thus, MoSERS demonstrates the potential for molecular stratification of cancer patients using circulating EVs.

Ultrasensitive protein detection technologies for extracellular vesicle measurements

Extracellular Vesicles (EVs) are nanoscopic, heterogenous, lipid-rich particles that carry a multitude of cargo biomolecules including proteins, nucleic acids, and metabolites. Although historically, EVs were regarded as cellular debris with no intrinsic value, growing understanding of EV biogenesis has led to the realization that EVs facilitate intercellular communication and are sources of liquid biomarkers. EVs can be isolated and analyzed from a wide variety of accessible biofluids for biomarker discovery and diagnostic applications. There is a diversity of EVs from different biological compartments (e.g., cells, tissues) and some of these EVs are present at extremely low concentrations. Consequently, a challenge in the field is to find appropriate markers that enable selective isolation of these rare EVs. Many conventional protein detection technologies have limited sensitivity to detect low abundance biomarkers in EVs, limiting their use in EV research. Advances in ultrasensitive detection technologies are needed to harness the potential of EVs for clinical application. This Perspective highlights current EV research focusing on ultrasensitive detection technologies, their limitations, and areas of potential growth in the future.

KRAS mutation: The booster of pancreatic ductal adenocarcinoma transformation and progression

Pancreatic ductal adenocarcinoma (PDAC) is the most common type of pancreatic cancer. It has a poor response to conventional therapy and has an extremely poor 5-year survival rate. PDAC is driven by multiple oncogene mutations, with the highest mutation frequency being observed in KRAS. The KRAS protein, which binds to GTP, has phosphokinase activity, which further activates downstream effectors. KRAS mutation contributes to cancer cell proliferation, metabolic reprogramming, immune escape, and therapy resistance in PDAC, acting as a critical driver of the disease. Thus, KRAS mutation is positively associated with poorer prognosis in pancreatic cancer patients. This review focus on the KRAS mutation patterns in PDAC, and further emphases its role in signal transduction, metabolic reprogramming, therapy resistance and prognosis, hoping to provide KRAS target therapy strategies for PDAC.

Multiplexed analysis of EV reveals specific biomarker composition with diagnostic impact

Exosomes and extracellular vesicles (EV) are increasingly being explored as circulating biomarkers, but their heterogenous composition will likely mandate the development of multiplexed EV technologies. Iteratively multiplexed analyses of near single EVs have been challenging to implement beyond a few colors during spectral sensing. Here we developed a multiplexed analysis of EV technique (MASEV) to interrogate thousands of individual EVs during 5 cycles of multi-channel fluorescence staining for 15 EV biomarkers. Contrary to the common belief, we show that: several markers proposed to be ubiquitous are less prevalent than believed; multiple biomarkers concur in single vesicles but only in small fractions; affinity purification can lead to loss of rare EV subtypes; and deep profiling allows detailed analysis of EV, potentially improving the diagnostic content. These findings establish the potential of MASEV for uncovering fundamental EV biology and heterogeneity and increasing diagnostic specificity.

From Conventional to Microfluidic: Progress in Extracellular Vesicle Separation and Individual Characterization

Extracellular vesicles (EVs) are nanoscale membrane vesicles, which contain a wide variety of cargo such as proteins, miRNAs, and lipids. A growing body of evidence suggests that EVs are promising biomarkers for disease diagnosis and therapeutic strategies. Although the excellent clinical value, their use in personalized healthcare practice is not yet feasible due to their highly heterogeneous nature. Taking the difficulty of isolation and the small size of EVs into account, the characterization of EVs at a single-particle level is both imperative and challenging. In a bid to address this critical point, more research has been directed into a microfluidic platform because of its inherent advantages in sensitivity, specificity, and throughput. This review discusses the biogenesis and heterogeneity of EVs and takes a broad view of state-of-the-art advances in microfluidics-based EV research, including not only EV separation, but also the single EV characterization of biophysical detection and biochemical analysis. To highlight the advantages of microfluidic techniques, conventional technologies are included for comparison. The current status of artificial intelligence (AI) for single EV characterization is then presented. Furthermore, the challenges and prospects of microfluidics and its combination with AI applications in single EV characterization are also discussed. In the foreseeable future, recent breakthroughs in microfluidic platforms are expected to pave the way for single EV analysis and improve applications for precision medicine.

Plasmon-Enhanced Single Extracellular Vesicle Analysis for Cholangiocarcinoma Diagnosis

Cholangiocarcinoma (CCA) is a fatal disease often detected late in unresectable stages. Currently, there are no effective diagnostic methods or biomarkers to detect CCA early with high confidence. Analysis of tumor-derived extracellular vesicles (tEVs) harvested from liquid biopsies can provide a new opportunity to achieve this goal. Here, an advanced nanoplasmonic sensing technology is reported, termed FLEX (fluorescence-amplified extracellular vesicle sensing technology), for sensitive and robust single EV analysis. In the FLEX assay, EVs are captured on a plasmonic gold nanowell surface and immunolabeled for cancer-associated biomarkers to identify tEVs. The underlying plasmonic gold nanowell structures then amplify EVs' fluorescence signals, an effective amplification process at the single EV level. The FLEX EV analysis revealed a wide heterogeneity of tEVs and their marker levels. FLEX also detected small tEVs not detected by conventional EV fluorescence imaging due to weak signals. Tumor markers (MUC1, EGFR, and EPCAM) are identified in CCA, and this marker combination is applied to detect tEVs in clinical bile samples. The FLEX assay detected CCA with an area under the curve of 0.93, significantly better than current clinical markers. The sensitive and accurate nanoplasmonic EV sensing technology can aid in early CCA diagnosis.

Liquid biopsy in pancreatic cancer - Current perspective and future outlook

Pancreatic cancer is a lethal condition with a rising incidence and often presents at an advanced stage, contributing to abysmal five-year survival rates. Unspecific symptoms and the current lack of biomarkers and screening tools hamper early diagnosis. New technologies for liquid biopsies and their respective evaluation in pancreatic cancer patients have emerged over recent years. The term liquid biopsy summarizes the sampling and analysis of circulating tumor cells (CTCs), small extracellular vesicles (sEVs), and tumor DNA (ctDNA) from body fluids. The major advantages of liquid biopsies rely on their minimal invasiveness and repeatability, allowing serial sampling for dynamic insights to aid diagnosis, particularly early detection, risk stratification, and precision medicine in pancreatic cancer. However, liquid biopsies have not yet developed into a new pillar for clinicians' routine armamentarium. Here, we summarize recent findings on the use of liquid biopsy in pancreatic cancer patients. We discuss current challenges and future perspectives of this potentially powerful alternative to conventional tissue biopsies.

Extracellular vesicles for precision medicine in prostate cancer - Is it ready for clinical translation?

Biofluid-based biomarker tests hold great promise for precision medicine in prostate cancer (PCa) clinical practice. Extracellular vesicles (EV) are established as intercellular messengers in cancer development with EV cargos, including protein and nucleic acids, having the potential to serve as biofluid-based biomarkers. Recent clinical studies have begun to evaluate EV-based biomarkers for PCa diagnosis, prognosis, and disease/therapy resistance monitoring. Promising results have led to PCa EV biomarker validation studies which are currently underway with the next challenge being translation to robust clinical assays. However, EV research studies generally use low throughput EV isolation methods and costly molecular profiling technologies that are not suitable for clinical assays. Here, we consider the technical hurdles in translating EV biomarker research findings into precise and cost-effective clinical biomarker assays. Novel microfluidic devices coupling EV extraction with sensitive antibody-based biomarker detection are already being explored for point-of-care applications for rapid provision in personalised medicine approaches.

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.

Current Advances in Technologies for Single Extracellular Vesicle Analysis and Its Clinical Applications in Cancer Diagnosis

Extracellular vesicles (EVs) have been regarded as one of the most potential diagnostic biomarkers for different cancers, due to their unique physiological and pathological functions. However, it is still challenging to precisely analyze the contents and sources of EVs, due to their heterogeneity. Herein, we summarize the advances in technologies for a single EV analysis, which may provide new strategies to study the heterogeneity of EVs, as well as their cargo, more specifically. Furthermore, the applications of a single EV analysis on cancer early diagnosis are also discussed.

Current Status of the Diagnosis of Early-Stage Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) can be treated with surgery, chemotherapy, and radiotherapy. Despite medical progress in each field in recent years, it is still insufficient for managing PDAC, and at present, the only curative treatment is surgery. A typical pancreatic cancer is relatively easy to diagnose with imaging. However, it is often not recommended for surgical treatment at the time of diagnosis due to metastatic spread beyond the pancreas. Even if it is operable, it often recurs during postoperative follow-up. In the case of PDAC with a diameter of 10 mm or less, the 5-year survival rate is as good as 80% or more, and the best index for curative treatment is tumor size. The early detection of pancreatic cancer with a diameter of less than 10 mm or carcinoma in situ is critical. Here, we provide an overview of the current status of diagnostic imaging features and genetic tests for the accurate diagnosis of early-stage PDAC.

Extracellular vesicles as source for the identification of minimally invasive molecular signatures in glioblastoma

The analysis of extracellular vesicles (EVs) as a source of cancer biomarkers is an emerging field since low-invasive biomarkers are highly demanded. EVs constitute a heterogeneous population of small membrane-contained vesicles that are present in most of body fluids. They are released by all cell types, including cancer cells and their cargo consists of nucleic acids, proteins and metabolites and varies depending on the biological-pathological state of the secretory cell. Therefore, EVs are considered as a potential source of reliable biomarkers for cancer. EV biomarkers in liquid biopsy can be a valuable tool to complement current medical technologies for cancer diagnosis, as their sampling is minimally invasive and can be repeated over time to monitor disease progression. In this review, we highlight the advances in EV biomarker research for cancer diagnosis, prognosis, and therapy monitoring. We especially focus on EV derived biomarkers for glioblastoma. The diagnosis and monitoring of glioblastoma still relies on imaging techniques, which are not sufficient to reflect the highly heterogenous and invasive nature of glioblastoma. Therefore, we discuss how the use of EV biomarkers could overcome the challenges faced in diagnosis and monitoring of glioblastoma.