Protein typing of circulating microvesicles allows real-time monitoring of glioblastoma therapy

Mycobacterium tuberculosis extracellular vesicles: exploitation for vaccine technology and diagnostic methods

Tuberculosis (TB) is a fatal epidemic disease usually caused by Mycobacterium tuberculosis (Mtb). Pervasive latent infection, multidrug- and extensively drug-resistant tuberculosis (MDR- and XDR-TB), and TB/HIV co-infection make TB a global health problem, which emphasises the design and development of efficient vaccines and diagnostic biomarkers. Extracellular vesicles (EVs) secretion is a conserved phenomenon in all the domains of life. Various cargos such as nucleic acids, toxins, lipoproteins, and enzymes have been recognised in these nano-sized vesicles that may be involved in bacterial physiology and pathogenesis. The intrinsic adjuvant effect, native immunogenic cargo, sensing by host immune cells, circulation in all body fluids, and comprehensive distribution of antigens introduce EVs as a promising tool for designing novel vaccines, diagnostic biomarkers, and drug delivery systems. Genetic engineering of the EV-producing bacteria and the subsequent production of proper EVs could facilitate the development of the EV-based therapeutic applications. Recently, it was demonstrated that thick-walled mycobacteria release EVs, which contain immunodominant cargos such as lipoglycans and lipoproteins. The present article is a comprehensive review on the recent findings of Mtb EVs biology and the exploitation of EVs for the vaccine technology and diagnostic methods.

Scalable Signature-Based Molecular Diagnostics Through On-chip Biomarker Profiling Coupled with Machine Learning

Molecular diagnostics have traditionally relied on discrete biological substances as diagnostic markers. In recent years however, advances in on-chip biomarker screening technologies and data analytics have enabled signature-based diagnostics. Such diagnostics aim to utilize unique combinations of multiple biomarkers or diagnostic 'fingerprints' rather than discrete analyte measurements. This approach has shown to improve both diagnostic accuracy and diagnostic specificity. In this review, signature-based diagnostics enabled by microfluidic and micro-/nano- technologies will be reviewed with a focus on device design and data analysis pipelines and methodologies. With increasing amounts of data available from microfluidic biomarker screening, isolation, and detection platforms, advanced data handling and analytics approaches can be employed. Thus, current data analysis approaches including machine learning and recent advances with image processing, along with potential future directions will be explored. Lastly, the needs and gaps in current literature will be elucidated to inform future efforts towards development of molecular diagnostics and biomarker screening technologies.

Potential biomarkers and challenges in glioma diagnosis, therapy and prognosis

Gliomas are the most common central nervous system malignancies and present with significant morbidity and mortality. Treatment modalities are currently limited to surgical resection, chemotherapy and radiotherapy. Increases in survival rate over the previous decades are negligible, further pinpointing an unmet clinical need in this field. There is a continual struggle with the development of effective glioma diagnostics and therapeutics, largely due to a multitude of factors, including the presence of the blood–brain barrier and significant intertumoural and intratumoural heterogeneity. Importantly, there is a lack of reliable biomarkers for glioma, particularly in aiding tumour subtyping and measuring response to therapy. There is a need for biomarkers that would both overcome the complexity of the disease and allow for a minimally invasive means of detection and analysis. This is a comprehensive review evaluating the potential of current cellular, proteomic and molecular biomarker candidates for glioma. Significant hurdles faced in glioma diagnostics and therapy are also discussed here.

Plasmon-Enhanced Biosensing for Multiplexed Profiling of Extracellular Vesicles

Extracellular vesicles (EVs)-nanoscale phospholipid vesicles secreted by cells-present new opportunities for molecular diagnosis from non-invasive liquid biopsies. Single EV protein analysis can be extremely valuable in studying EVs as circulating cancer biomarkers, but it is technically challenging due to weak detection signals associated with limited amounts of epitopes and small surface areas for antibody labeling. Here, a new, simple method that enables multiplexed analyses of EV markers with improved sensitivities is reported. Specifically, plasmon-enhanced fluorescence detection is implemented that amplifies fluorescence signals using surface plasmon resonances excited by periodic gold nanohole structures. It is shown that fluorescence signals in multiple channels are amplified by one order of magnitude, and both transmembrane and intravesicular markers can be detected at the single EV level. This approach can offer additional insight into understanding subtypes, heterogeneity, and production dynamics of EVs during disease development and progression.

Proteomic Analysis of Exosomes for Discovery of Protein Biomarkers for Prostate and Bladder Cancer

Extracellular vesicles (EVs) are released by nearly all cell types as part of normal cell physiology, transporting biological cargo, including nucleic acids and proteins, across the cell membrane. In pathological states such as cancer, EV-derived cargo may mirror the altered state of the cell of origin. Exosomes are the smaller, 50–150 nanometer-sized EVs released from fusion of multivesicular endosomes with the plasma membrane. Exosomes play important roles in cell-cell communication and participate in multiple cancer processes, including invasion and metastasis. Therefore, proteomic analysis of exosomes is a promising approach to discover potential cancer biomarkers, even though it is still at an early stage. Herein, we critically review the advances in exosome isolation methods and their compatibility with mass spectrometry (MS)-based proteomic analysis, as well as studies of exosomes in pathogenesis and progression of prostate and bladder cancer, two common urologic cancers whose incidence rates continue to rise annually. As urological tumors, both urine and blood samples are feasible for noninvasive or minimally invasive analysis. A better understanding of the biological cargo and functions of exosomes via high-throughput proteomics will help provide new insights into complex alterations in cancer and provide potential therapeutic targets and personalized treatment for patients.

Characterization of single microvesicles in plasma from glioblastoma patients

BACKGROUND

Extracellular vesicles (EV) are shed by tumor cells but little is known about their individual molecular phenotypes and heterogeneity. While exosomes have received considerable attention, much less is known about larger microvesicles. Here we profile single microvesicles (MV) and exosomes from glioblastoma (GB) cells and MV from the plasma of patients.

METHODS

EV secreted from mouse glioma GL261 and human primary GBM8 cell lines as well as from the plasma of 8 patients with diagnoses of GB and 2 healthy controls were isolated and processed for single vesicle analysis. EV were immobilized on glass slides and the heterogeneity of vesicle and tumor markers were analyzed at the single vesicle level.

RESULTS

We show that (i) MV are abundant, (ii) only a minority of MV expresses putative MV markers, and (iii) MV share tetraspanin biomarkers previously thought to be diagnostic of exosomes. Using MV capture and staining techniques that allow differentiation of host cell and GB-derived MV we further demonstrate that (i) tumoral MV often present as <10% of all MV in GB patient plasma, and (ii) there is extensive heterogeneity in tumor marker expression in these tumor-derived MV.

CONCLUSION

These results indicate that single MV analysis is likely necessary to identify rare tumoral MV populations and the single vesicle analytical technique used here can be applied to both MV and exosome fractions without the need for their separation from each other. These studies form the basis for using single EV analyses for cancer diagnostics.

Blood Biomarkers of Glioma in Response Assessment Including Pseudoprogression and Other Treatment Effects: A Systematic Review

Imaging-based monitoring of disease burden in glioma patients is frequently confounded by treatment effects. Circulating biomarkers could theoretically augment imaging-based response monitoring. This systematic review aimed to present and evaluate evidence for differential expression and diagnostic accuracy of circulating biomarkers with respect to outcomes of tumor response, progression, stable disease, and treatment effects (pseudoprogression, radionecrosis, pseudoresponse, and pseudolesions) in patients undergoing treatment for World Health Organization grades II-IV diffuse astrocytic and oligodendroglial tumors. MEDLINE, EMBASE, Web Of Science, and SCOPUS databases were searched until August 18, 2019, for observational or diagnostic studies on multiple circulating biomarker types: extracellular vesicles, circulating nucleic acids, circulating tumor cells, circulating proteins, and metabolites, angiogenesis related cells, immune cells, and other cell lines. Methodological quality of included studies was assessed using an adapted Quality Assessment of Diagnostic Accuracy Studies-2 tool, and level of evidence (IA-IVD) for individual biomarkers was evaluated using an adapted framework from the National Comprehensive Cancer Network guidelines on evaluating tumor marker utility. Of 13,202 unique records, 58 studies met the inclusion criteria. One hundred thirty-three distinct biomarkers were identified in a total of 1,853 patients across various treatment modalities. Fifteen markers for response, progression, or stable disease and five markers for pseudoprogression or radionecrosis reached level IB. No biomarkers reached level IA. Only five studies contained data for diagnostic accuracy measures. Overall methodological quality of included studies was low. While extensive data on biomarker dysregulation in varying response categories were reported, no biomarkers ready for clinical application were identified. Further assay refinement and evaluation in larger cohorts with diagnostic accuracy study designs are required. PROSPERO Registration: CRD42018110658.

Evidence of sequestration of triclabendazole and associated metabolites by extracellular vesicles of Fasciola hepatica

Fascioliasis is a neglected zoonotic disease that infects humans and ruminant species worldwide. In the absence of vaccines, control of fascioliasis is primarily via anthelminthic treatment with triclabendazole (TCBZ). Parasitic flatworms, including Fasciola hepatica, are active secretors of extracellular vesicles (EVs), but research has not been undertaken investigating EV anthelmintic sequestration. Adult F. hepatica were cultured in lethal and sub-lethal doses of TCBZ and its active metabolites, in order to collect EVs and evaluate their morphological characteristics, production and anthelmintic metabolite content. Transmission electron microscopy demonstrated that F. hepatica exposed to TCBZ and its metabolites produced EVs of similar morphology, compared to non-TCBZ exposed controls, even though TCBZ dose and/or TCBZ metabolite led to measurable structural changes in the treated F. hepatica tegument. qNano particle analysis revealed that F. hepatica exposed to TCBZ and its metabolites produced at least five times greater EV concentrations than non-TCBZ controls. A combined mass spectrometry and qNano particle analysis confirmed the presence of TCBZ and the TCBZ–sulphoxide metabolite in anthelmintic exposed EVs, but limited TCBZ sulphone was detectable. This data suggests that EVs released from adult F. hepatica have a biological role in the sequestration of TCBZ and additional toxic xenobiotic metabolites.

Exosomes as drug delivery systems: A brief overview and progress update

Exosomes are intracellular membrane-based vesicles with diverse compositions that are involved in biological and pathological processes. Since the discovery of exosomes, they have been used as diagnostic biomarkers and as potential drug delivery vehicles based on their size and competence to transfer biological materials to recipient cells. The properties of exosomes such as biocompatibility, preferred tumor homing, adjustable targeting efficiency, and stability make them striking and excellent drug delivery vehicles for use in various diseases and cancer therapy. In this article, we provide a brief overview of the biogenesis, functions, and contents of exosomes along with the separation and characterization techniques. Our major focus is on the recent progress made in application of exosomes as drug delivery systems involving delivery of small molecules, macromolecules, and nucleotides. Further, we discuss the challenges faced when using exosomes as a drug delivery vehicle.

Characterizing Extracellular Vesicles and Their Diverse RNA Contents

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

Exosomes

Exosomes are small, single-membrane, secreted organelles of ∼30 to ∼200 nm in diameter that have the same topology as the cell and are enriched in selected proteins, lipids, nucleic acids, and glycoconjugates. Exosomes contain an array of membrane-associated, high-order oligomeric protein complexes, display pronounced molecular heterogeneity, and are created by budding at both plasma and endosome membranes. Exosome biogenesis is a mechanism of protein quality control, and once released, exosomes have activities as diverse as remodeling the extracellular matrix and transmitting signals and molecules to other cells. This pathway of intercellular vesicle traffic plays important roles in many aspects of human health and disease, including development, immunity, tissue homeostasis, cancer, and neurodegenerative diseases. In addition, viruses co-opt exosome biogenesis pathways both for assembling infectious particles and for establishing host permissiveness. On the basis of these and other properties, exosomes are being developed as therapeutic agents in multiple disease models.

Biomarker Organization in Circulating Extracellular Vesicles: New Applications in Detecting Neurodegenerative Diseases

Neurodegenerative diseases are heterogeneous disorders characterized by a progressive loss of function and/or death of nerve cells, leading to severe cognitive and functional decline. Due to the complex pathology, early detection and intervention are critical to the development of successful treatments; however, current diagnostic approaches are limited to subjective, late-stage clinical findings. Extracellular vesicles (EVs) have recently emerged as a promising circulating biomarker for neurodegenerative diseases. Actively released by diverse cells, EVs are nanoscale membrane vesicles. They abound in blood, readily cross the blood-brain barrier, and carry diverse molecular cargoes in different organizational states: these molecular cargoes are inherited from the parent cells or bound to the EV membrane through surface associations. Specifically, EVs have been found to be associated with several important pathogenic proteins of neurodegenerative diseases, and their involvement could alter disease progression. This article provides an overview of EVs as circulating biomarkers of neurodegenerative diseases and introduces new technological advances to characterize the biophysical properties of EV-associated biomarkers for accurate, blood-based detection of neurodegenerative diseases.

Exosomes: Multiple-targeted multifunctional biological nanoparticles in the diagnosis, drug delivery, and imaging of cancer cells

Exosomes are biological nanoparticles (30-150 nm) secreted in the extracellular area from all of cells, that mediate intercellular message. Exosomes act as the carriers for numerous proteins, DNAs, RNAs and cell-signaling molecules. Therefore, exosomes secreted by the tumor cells are useful for diagnostic purposes because of their persistent presence in the blood and their provision of genetic cargo similar to those in tumor. Due to the risks of aggressive activity and ambiguity of biological activity in other tissues, the use of exosomes in drug delivery and imaging has been limited. However, their high loading, stability and longer circulation time, excellent targeting, high cell penetration performance, and optimal biodegradability have made them potential agents in targeted cancer treatment. Therefore, in addition to examining methods for isolating and loading exosomes, this paper discusses the applications of exosomes in biological measurement, imaging, and therapeutic activities. Also, this review describes the challenges of using exosomes compared to conventional methods and shows that it is very useful to use them due to less aggressive activities. Finally, this review attempts to provide an appropriate incentive by showing the performance of exosomes in cancer therapy through targeted drug delivery, gene therapy, imaging and diagnosis.

Technologies and Standardization in Research on Extracellular Vesicles

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

Molecular and functional extracellular vesicle analysis using nanopatterned microchips monitors tumor progression and metastasis

Longitudinal cancer monitoring is crucial to clinical implementation of precision medicine. There is growing evidence indicating important functions of extracellular vesicles (EVs) in tumor progression and metastasis, including matrix remodeling via transporting matrix metalloproteases (MMPs). However, the clinical relevance of EVs remains largely undetermined, partially owing to challenges in EV analysis. Distinct from existing technologies mostly focused on characterizing molecular constituents of EVs, here we report a nanoengineered lab-on-a-chip system that enables integrative functional and molecular phenotyping of tumor-associated EVs. A generalized, high-resolution colloidal inkjet printing method was developed to allow robust and scalable manufacturing of three-dimensional (3D) nanopatterned devices. With this nanochip platform, we demonstrated integrative analysis of the expression and proteolytic activity of MMP14 on EVs to detect in vitro cell invasiveness and monitor in vivo tumor metastasis, using cancer cell lines and mouse models. Analysis of clinical plasma specimen showed that our technology could be used for cancer detection including accurate classification of age-matched controls and patients with ductal carcinoma in situ, invasive ductal carcinoma, or locally metastatic breast cancer in a training cohort (n = 30, 96.7% accuracy) and an independent validation cohort (n = 70, 92.9% accuracy). With clinical validation, our technology could provide a useful liquid biopsy tool to improve cancer diagnostics and real-time surveillance of tumor evolution in patients to inform personalized therapy.

The Roles of Exosomes in Visual and Auditory Systems

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

Circulating extracellular vesicle-associated TGFβ3 modulates response to cytotoxic therapy in head and neck squamous cell carcinoma

Management of locally advanced head and neck squamous cell carcinoma (HNSCC) requires a multi-prong approach comprising surgery, radiation and/or chemotherapy, yet outcomes are limited. This is largely due to a paucity of biomarkers that can predict response to specific treatment modalities. Here, we evaluated TGFβ3 protein levels in extracellular vesicles (EVs) released by HNSCC cells as a predictor for response to chemoradiation therapy (CRT). To this end, specific EV-fractions were isolated from cell lines or HNSCC patient plasma, and TGFβ3 protein was quantified. In patients treated with CRT, TGFβ3 levels were found to be significantly higher in plasma EV-fractions or non-responders compared with responders. High levels of TGFβ3 levels in Annexin V-EVs were associated with the worst progression-free survival. In vitro experiments demonstrated that TGFβ3 silencing sensitized HNSCC cells to cytotoxic therapies, and this phenotype could be rescued by treatment with exogenous. In addition, specific EV-fractions shed by cisplatin-resistant cells were sufficient to transfer the resistant phenotype to sensitive cells through activation of TGFβ-signaling pathway. Therefore, our data show that TGFβ3 transmitted through EV plays a significant role in response to cytotoxic therapy, which can be exploited as a potential biomarker for CRT response in HNSCC patients treated with curative intent.

Advances in extracellular vesicles analysis

Extracellular vesicles (EVs) play an important role in intercellular communication in normal cellular process and pathological conditions by facilitating the transport of cellular content from one cell to another. EVs as conveyors of various biological molecules with their ability to redirect effects on a target cell physiological function in cell type-specific manner makes EVs an excellent candidate for drug delivery vehicle in disease therapy. Moreover, unique characteristics and contents of EVs which differ depends on cellular origin and physiological state make them a valuable source of diagnostic biomarker. Herein, we review the current progress in extracellular vesicle (EV) analysis, its transition from biomedical research to advancing therapy, and recent pioneered approaches to characterize and quantify EVs' subclasses with an emphasis on the integration of advanced technologies for both qualitative and quantitative analysis of EVs in different clinical tissue/body fluid samples.

Urinary Extracellular Vesicles as Biomarkers of Kidney Disease: From Diagnostics to Therapeutics

Cell-derived extracellular vesicles (EVs) can be isolated from various body fluids, including urine. Urinary EVs have gained important recognition as potential diagnostic biomarkers in renal disease since their cargo includes nucleic acids, proteins, and other cellular components, which likely mirror the physiological and possibly pathophysiological state of cells along the nephron. Accumulating evidence highlights the feasibility of using EVs as biomarkers for diagnostic, prognostic, and therapeutic purposes in several forms of renal disease, such as acute kidney injury, glomerulonephritis, and renal transplantation. Additionally, exogenous delivery of EVs released in vitro by cells in culture may have salutary benefits for renal diseases. In this review, we introduce recent studies that attempt to identify urinary EVs as candidate biomarkers for human kidney diseases and consider their potential implication as a therapeutic option in key kidney diseases.

Exosome-templated nanoplasmonics for multiparametric molecular profiling

Exosomes are nanoscale vesicles distinguished by characteristic biophysical and biomolecular features; current analytical approaches, however, remain univariate. Here, we develop a dedicated platform for multiparametric exosome analysis-through simultaneous biophysical and biomolecular evaluation of the same vesicles-directly in clinical biofluids. Termed templated plasmonics for exosomes, the technology leverages in situ growth of gold nanoshells on vesicles to achieve multiselectivity. For biophysical selectivity, the nanoshell formation is templated by and tuned to distinguish exosome dimensions. For biomolecular selectivity, the nanoshell plasmonics locally quenches fluorescent probes only if they are target-bound on the same vesicle. The technology thus achieves multiplexed analysis of diverse exosomal biomarkers (e.g., proteins and microRNAs) but remains unresponsive to nonvesicle biomarkers. When implemented on a microfluidic, smartphone-based sensor, the platform is rapid, sensitive, and wash-free. It not only distinguished biomarker organizational states in native clinical samples but also showed that the exosomal subpopulation could more accurately differentiate patient prognosis.

Electron Microscopy-Based Comparison and Investigation of the Morphology of Exosomes Derived from Hepatocellular Carcinoma Cells Isolated at Different Centrifugal Speeds

Exosomes derived from hepatocellular carcinoma (HCC) cells are nanovesicles and are involved in the occurrence and development of HCC, they also serve as important carriers and drug targets of nanodrug delivery systems. The external shape and internal structure of exosomes are important indexes of identification, and isolated intact morphology is crucial to biological function integrity. However, given their susceptibility to various influencing factors, the external shape and internal structure of exosomes derived from HCC cells remain incompletely studied. In this study, exosomes purified from HCC cells were isolated at different centrifugation speeds and examined via multiple electron microscopy (EM) techniques. The results demonstrate that exosomes possess a nearly spherical shape and bilipid membranous vesicle with a concave cavity structure containing electron-dense and coated vesicles, suggesting the possible existence of subpopulations of exosomes with specific functions. The exosomes isolated at ultracentrifugation (UC) speed (≥110,000×g) presented irregular and diverse external morphologies, indicating the effect on the integrity of the exosomes. Transforming growth factor signaling bioactive substances (TGF-β1, S100A8, and S100A9) can be found in exosomes by performing Western blotting, showing that the internal content is associated with metastasis of HCC. These findings show that EMelectron microscopy and UC speed can affect exosome characteristics, including external shape, internal structure, and content of bioactive substances. The electron-dense and coated vesicles that had been discovered in exosomes might become new additional morphological features, which could help to improve the interpretation of experimental results and widen our understanding of exosome morphology.

Microfluidics and Nanomaterial-based Technologies for Circulating Tumor Cell Isolation and Detection

Cancer has been one of the leading causes of death globally, with metastases and recurrences contributing to this result. The detection of circulating tumor cells (CTCs), which have been implicated as a major population of cells that is responsible for seeding and migration of tumor sites, could contribute to early detection of metastasis and recurrences, consequently increasing the chances of cure. This review article focuses on the current progress in microfluidics technology in CTCs diagnostics, extending to the use of nanomaterials and surface modification techniques for diagnostic applications, with an emphasis on the importance of integrating microchannels, nanomaterials, and surface modification techniques in the isolating and detecting of CTCs.

Enabling Sensitive Phenotypic Profiling of Cancer-Derived Small Extracellular Vesicles Using Surface-Enhanced Raman Spectroscopy Nanotags

Circulating cancer-derived small extracellular vesicles (EVs) are nanoscale membranous vesicles shed from cancer cells that are released into surrounding body fluids. Small EVs contain biomolecules associated with cancer such as DNA and proteins for cell-to-cell communication. Therefore, small EVs have been regarded as important cancer biomarkers for liquid biopsy-based cancer diagnosis and drug treatment monitoring. However, because of the high heterogeneity and low level of small EVs in body fluids, there is a high demand for sensitive detection and characterization of such vesicles at a molecular level. In this study, we have developed a sensitive and effective approach to simultaneously profile multiple protein biomarkers expressed on cancer-derived small EVs using surface-enhanced Raman spectroscopy (SERS) nanotags in a single test, without complex isolation steps. Rapid and multiplexed phenotypic profiling of small EVs is achieved by mixing specific detection antibody-coated SERS nanotags, filtered conditioned EV-suspended medium (conditioned EVs), and capture antibody (CD63)-conjugated magnetic beads to form a sandwich immunoassay. As a proof-of-concept demonstration, we applied this approach to characterize pancreatic cancer-derived EVs by simultaneously detecting three specific EV surface receptors including Glypican-1, epithelial cell adhesion molecules (EpCAMs), and CD44 variant isoform 6 (CD44V6). The sensitivity of this method was measured down to 2.3 × 10⁶ particles/mL, which is more sensitive and shows higher multiplexing capability than most other reported EV profiling techniques, such as western blot, enzyme-linked immunosorbent assay, and flow cytometry. Furthermore, phenotypic profiling of small EVs from colorectal cancer and bladder cancer cell lines (SW480 and C3) was conducted and compared to those derived from pancreatic cancer (Panc-1), highlighting the significant difference in EV phenotypes for various cancer cell types suspended in both phosphate-buffered saline and plasma. Thus, we believe that this technology enables a comprehensive evaluation of small secreted EV heterogeneity with high sensitivity, offering strong potential for accurate noninvasive cancer diagnosis and monitoring of drug treatment. In addition, this assay provides point-of-care use because of the easy sample preparation and portable nature of the Raman spectrometer.

Progress in Microfluidics-Based Exosome Separation and Detection Technologies for Diagnostic Applications

Exosomes are secreted by most cell types and circulate in body fluids. Recent studies have revealed that exosomes play a significant role in intercellular communication and are closely associated with the pathogenesis of disease. Therefore, exosomes are considered promising biomarkers for disease diagnosis. However, exosomes are always mixed with other components of body fluids. Consequently, separation methods for exosomes that allow high-purity and high-throughput separation with a high recovery rate and detection techniques for exosomes that are rapid, highly sensitive, highly specific, and have a low detection limit are indispensable for diagnostic applications. For decades, many exosome separation and detection techniques have been developed to achieve the aforementioned goals. However, in most cases, these two techniques are performed separately, which increases operation complexity, time consumption, and cost. The emergence of microfluidics offers a promising way to integrate exosome separation and detection functions into a single chip. Herein, an overview of conventional and microfluidics-based techniques for exosome separation and detection is presented. Moreover, the advantages and drawbacks of these techniques are compared.

[Progress in extracellular vesicle imaging methods]

Extracellular vesicles (EVs), including exosomes and microvesicles, are lipid bilayer-enclosed nanovesicles secreted by cells. These EVs are important mediators of intercellular communication by serving as vehicles for transfer of proteins, mRNA, miRNA and lipids between cells. Various visualization methods have been established to explore the characteristics of EVs and their role in physiological and pathological processes. The nanoscale size and high heterogeneity of EVs hamper the identification of their biological characteristics and functions. This review presents a comprehensive overview of EV imaging methods in light of the origin, separation and dynamic tracking of EVs, and the advantages and disadvantages of different imaging strategies are discussed. We believe that studies at the levels of single vesicles and single cells will become the frontier of future researches of EVs.

Cancer Liquid Biopsy Using Integrated Microfluidic Exosome Analysis Platforms

Liquid biopsies serve as both powerful noninvasive diagnostic tools for early cancer screening and prognostic tools for monitoring cancer progression and treatment efficacy. Exosomes are promising biomarkers for liquid biopsies, since these nano-sized extracellular vesicles (EVs) enrich proteins, lipids, mRNAs, and miRNAs from cells of origin, including cancer cells. Although exosomes are abundantly present in various bodily fluids, conventional exosome isolation and detection methods that rely on benchtop equipment are time-consuming, expensive, and involve complicated non-portable procedures. As an alternative, recently developed microfluidic platforms can perform effective exosome separation and detection for liquid biopsies using a single device. Such methods offer advantages of integrity, speed, cost-efficiency, and portability over conventional benchtop and early microfluidic-based single-functional methods which can only separate or detect exosomes separately. These advances have made exosome-based point-of-care (POC) applications possible. This review outlines recent integrated microfluidic-based exosomal detection strategies to guide future development of such devices for use in liquid biopsies for early cancer screening, prognostic monitoring, and other potential POC applications.

Cell derived extracellular vesicles: from isolation to functionalization and biomedical applications

Extracellular vesicles (EVs) are shed from most mammalian cells by different processes. EVs possess several distinct advantages, including excellent biocompatibility, good bio-stability and low immunogenicity. Moreover, they play significant roles in physiological and pathological processes. Challenges in EV research mainly concern highly efficient isolation, specific membrane surface engineering and further development of EV applications in biomedical fields. In this review, we summarize the recent and representative research regarding isolation, engineering and biomedical applications of EVs, which represent important research focus areas. These three aspects have not ever been systematically classified and summarized in previous reviews. Finally, we give our insights into the key issues concerning EVs and their future development for biomedical applications.

Bioorthogonal Reactions Amplify Magnetic Nanoparticles Binding and Assembly for Ultrasensitive Magnetic Resonance Sensing

Conventional transverse relaxation time (T₂)-mediated magnetic resonance sensors (MRS) that utilizing the target-induces state change of magnetic nanoparticles (MNPs) mainly suffer from low sensitivity. Recent T₂-MRS that based on target-induced amount change of MNPs can achieve a higher sensitivity, but these sensors can hardly accommodate small molecules. We herein develop an ultrasensitive T₂-MRS that enable the detection of small molecules based on cascade bioorthogonal reactions (BRs)-realized MNPs binding and assembly. Benefiting from rapid and highly selective cascade BRs, a single small molecule target can not only increase MNPs binding but also assembly MNPs, which greatly amplifies T₂ signal for sensing based on both the state and amount change of MNPs for the first time. Our strategy is capable of sensing chlorpyrifos with a liner range of 0.1 ng/mL to 1000 ng/mL. We justify the practicability of our assay by detecting chlorpyrifos in apple and cabbage samples, whose accuracy is higher than that of enzyme linked immunosorbent assay. Our assay provides a cascade BRs-mediated MRS that can greatly broaden the use of T₂-based MRS for ultrasensitive sensing trace small molecules in complex samples.

Tracking extracellular vesicle phenotypic changes enables treatment monitoring in melanoma

Monitoring targeted therapy in real time for cancer patients could provide vital information about the development of drug resistance and improve therapeutic outcomes. Extracellular vesicles (EVs) have recently emerged as a promising cancer biomarker, and EV phenotyping shows high potential for monitoring treatment responses. Here, we demonstrate the feasibility of monitoring patient treatment responses based on the plasma EV phenotypic evolution using a multiplex EV phenotype analyzer chip (EPAC). EPAC incorporates the nanomixing-enhanced microchip and the multiplex surface-enhanced Raman scattering (SERS) nanotag system for direct EV phenotyping without EV enrichment. In a preclinical model, we observe the EV phenotypic heterogeneity and different phenotypic responses to the treatment. Furthermore, we successfully detect cancer-specific EV phenotypes from melanoma patient plasma. We longitudinally monitor the EV phenotypic evolution of eight melanoma patients receiving targeted therapy and find specific EV profiles involved in the development of drug resistance, reflecting the potential of EV phenotyping for monitoring treatment responses.

New Sensors for Extracellular Vesicles: Insights on Constituent and Associated Biomarkers

Extracellular vesicles (EVs) are diverse, nanoscale membrane vesicles released by cells into the circulation. As an emerging class of circulating biomarkers, EVs contain a trove of molecular information and play important roles in mediating intercellular communication. These EV molecular cargoes are differentially organized in the vesicles; they could be inherited from the parent cells or bound to the EV membrane through surface interactions. While the inherited constituents could serve as cell surrogate biomarkers, extravesicular association could reflect structural states of the bound molecules, revealing distinct subpopulations with different biophysical and/or biochemical properties. Despite the clinical potential of EVs and their diverse contents, conventional sensing technologies have limited compatibility to reveal nanoscale EV features. Complementary analytical platforms are being developed to address these technical challenges and expand the biomedical applications of EVs, to establish novel correlations and empower new diagnostics. This article provides a perspective on recent developments in sensor technologies to profile the diverse contents-different molecular types, quantities, and organizational states-in extracellular vesicles.

Exosome-specific tumor diagnosis via biomedical analysis of exosome-containing microRNA biomarkers

Exosome-containing microRNAs (exomiRs) can be employed as potential biomarkers for tumor diagnosis and have drawn much attention in the past few years. However, the separation of exosomes and the detection of exomiRs are still inconvenient or even difficult to implement. Thus, it is important to develop a simple, accurate, and reliable strategy for the separation of exosomes and the biomedical analysis of exomiRs. Herein, a novel exosome-specific tumor diagnosis strategy was constructed by integrating the rapid magnetic exosome-enrichment platform and the Ru(bpy)32+-polymer amplified electrochemiluminescence (ECL) strategy. This strategy realized the rapid and efficient capture of tumor-derived exosomes through a biological-affinity identification platform of the EpCAM antibody. The biomedical analysis of exomiRs achieved a preferable specificity and high sensitivity of 103 particles. Furthermore, we investigated the performance index for clinical blood samples from tumor patients; the results indicated that the exosome-specific tumor diagnosis strategy readily and consistently responded to exomiRs. These results indicated that the exosome-specific tumor diagnosis strategy provided new opportunities for the sensitive and efficient analysis of tumor-derived exomiRs. This strategy greatly simplified the biomedical analysis process and established the non-destructive detection mode of fluid biopsy for tumors.

Clinical implications of intratumor heterogeneity: challenges and opportunities

In this review, we highlight the role of intratumoral heterogeneity, focusing on the clinical and biological ramifications this phenomenon poses. Intratumoral heterogeneity arises through complex genetic, epigenetic, and protein modifications that drive phenotypic selection in response to environmental pressures. Functionally, heterogeneity provides tumors with significant adaptability. This ranges from mutual beneficial cooperation between cells, which nurture features such as growth and metastasis, to the narrow escape and survival of clonal cell populations that have adapted to thrive under specific conditions such as hypoxia or chemotherapy. These dynamic intercellular interplays are guided by a Darwinian selection landscape between clonal tumor cell populations and the tumor microenvironment. Understanding the involved drivers and functional consequences of such tumor heterogeneity is challenging but also promises to provide novel insight needed to confront the problem of therapeutic resistance in tumors.

Recent advancements in brain tumor targeting using magnetic nanoparticles

Transport of drugs through the blood-brain barrier to the brain and the toxic effects of drugs on the healthy cells can limit the effectiveness of chemotherapeutic agents. In recent years, magnetic nanoparticles (MNPs) have received much attention as targeted therapeutic and diagnostic systems due to their simplicity, ease of preparation and ability to tailor their properties such as their composition, size, surface morphology, etc. for biomedical applications. MNPs are utilized in drug delivery, radio therapeutics, hyperthermia treatment, gene therapy, biotherapeutics and diagnostic imaging. The present review will address the challenges in brain tumor targeting and discuss the application and recent developments in brain tumor targeting using MNPs.

de la Fuente J, Moros M. Nanoparticle-based biosensors for detection of extracellular vesicles in liquid biopsies

Selecting the appropriate nanoparticle, functionalization chemistry and sensing methodology can speed up the translation of liquid biopsies into the clinic.

Applications of extracellular vesicles in tissue regeneration

Extracellular vesicles (EVs) can be classified into several types based on their different biosyntheses or release pathways, including exosomes, microvesicles, apoptotic bodies, and large oncosomes. As they contain DNAs, RNAs, proteins, and other bioactive signals, EVs have been utilized in the diagnosis field for a long time. Considering the fact that stem cells have been widely used for tissue regeneration and EVs possess similar biological properties to their source cells, tissue regeneration abilities of EVs have recently attracted much attention in the regenerative medicine field. In this paper, recent advances and challenges of EVs applied in the repair and regeneration of damaged tissues, such as skin, heart, liver, kidney, bone, and central nervous system, have been summarized. Specifically, critical bioactive molecules, which are encapsulated within EVs and play significant roles in the tissue regeneration, have been highlighted. Finally, the prospects and future development directions of the application of EVs in the field of tissue regeneration have been discussed.

Is Alzheimer's Disease a Liver Disease of the Brain?

Clinical specialization is not only a force for progress, but it has also led to the fragmentation of medical knowledge. The focus of research in the field of Alzheimer's disease (AD) is neurobiology, while hepatologists focus on liver diseases and lipid specialists on atherosclerosis. This article on AD focuses on the role of the liver and lipid homeostasis in the development of AD. Amyloid-β (Aβ) deposits accumulate as plaques in the brain of an AD patient long before cognitive decline is evident. Aβ generation is a normal physiological process; the steady-state level of Aβ in the brain is determined by balance between Aβ production and its clearance. We present evidence suggesting that the liver is the origin of brain Aβ deposits and that it is involved in peripheral clearance of circulating Aβ in the blood. Hence the liver could be targeted to decrease Aβ production or increase peripheral clearance.

Extracellular vesicles and their role in glioblastoma

Research on the role of extracellular vesicles (EVs) in disease pathogenesis has been rapidly growing over the last two decades. As EVs can mediate intercellular communication, they can ultimately facilitate both normal and pathological processes through the delivery of their bioactive cargo, which may include nucleic acids, proteins and lipids. EVs have emerged as important regulators of brain tumors, capable of transferring oncogenic proteins, receptors, and small RNAs that may support brain tumor progression, including in the most common type of brain cancer, glioma. Investigating the role of EVs in glioma is crucial, as the most malignant glioma, glioblastoma (GBM), is incurable with a dismal median survival of 12-15 months. EV research in GBM has primarily focused on circulating brain tumor-derived vesicles in biofluids, such as blood and cerebrospinal fluid (CSF), investigating their potential as diagnostic and prognostic biomarkers. Gaining a greater understanding of the role of EVs and their cargo in brain tumor progression may contribute to the discovery of novel diagnostics and therapeutics. In this review, we summarize the known and emerging functions of EVs in glioma biology and pathogenesis, as well as their emerging biomarker potential.

Nanotechnology in Radiation Oncology

Nanotechnology has made remarkable contributions to clinical oncology. Nanotherapeutics and diagnostic tools have distinctive characteristics which allow them superior abilities to deliver therapeutics and imaging agents for radiation oncology. Compared to solid biopsies and imaging, the analysis of circulating tumor cells (CTCs) offers a more rapid, real-time, and less invasive method to monitor the dynamic molecular profiles of tumors. The potential of CTCs to be translated as a novel cancer biomarker has been demonstrated in numerous clinical studies. This review will discuss clinical applications of nanomaterials in radiation oncology and the implication of CTCs in cancer detection and monitoring.

Current Advances and Future Perspectives of Cerebrospinal Fluid Biopsy in Midline Brain Malignancies

OPINION STATEMENT

Malignancies arising in midline brain structures, including lymphomas, teratomas, germinomas, diffuse midline gliomas, and medulloblastomas typically respond to systemic therapies, and excessive surgical excision can result in serious complications, so that total surgical removal is not routinely performed. Identifying tumor specific biomarkers that can facilitate diagnosis at early stage and allow for dynamic surveillance of the tumor is of great clinical importance. However, existing standard methods for biopsy of these brain neoplasms are high risk, time consuming, and costly. Thus, less invasive and more rapid diagnosis tests are urgently needed to detect midline brain malignancies. Currently, tools for cerebrospinal biopsy of midline brain malignancies mainly include circulating tumor DNA, circulating tumor cells, and extracellular vesicles. Circulating tumor DNA achieved minimally invasive biopsy in several brain malignancies and has advantages in detecting tumor-specific mutations. In the field of tumor heterogeneity, circulating tumor cells better reflect the genome of tumors than surgical biopsy specimens. They can be applied for the diagnosis of leptomeningeal metastasis. Extracellular vesicles contain lots of genetic information about cancer cells, so they have potential in finding therapeutic targets and studying tumor invasion and metastasis.

Large and small extracellular vesicles released by glioma cells in vitro and in vivo

Tumour cells release diverse populations of extracellular vesicles (EVs) ranging in size, molecular cargo, and function. We sought to characterize mRNA and protein content of EV subpopulations released by human glioblastoma (GBM) cells expressing a mutant form of epidermal growth factor receptor (U87EGFRvIII) in vitro and in vivo with respect to size, morphology and the presence of tumour cargo. The two EV subpopulations purified from GBM U87EGFRvIII cancer cells, non-cancer human umbilical vein endothelial cells (HUVEC; control) and serum of U87EGFRvIII glioma-bearing mice using differential centrifugation (EVs that sediment at 10,000 × g or 100,000 × g are termed large EVs and small EVs, respectively) were characterized using transmission electron microscopy (TEM), confocal microscopy, nanoparticle tracking analysis (NTA), flow cytometry, immunofluorescence (IF), quantitative-polymerase chain reaction (qPCR), droplet digital polymerase chain reaction (ddPCR) and micro-nuclear magnetic resonance (μNMR). We report that both U87EGFRvIII and HUVEC release a similar number of small EVs, but U87EGFRvIII glioma cells alone release a higher number of large EVs compared to non-cancer HUVEC. The EGFRvIII mRNA from the two EV subpopulations from U87EGFRvIII glioma cells was comparable, while the EGFR protein (wild type + vIII) levels are significantly higher in large EVs. Similarly, EGFRvIII mRNA in large and small EVs isolated from the serum of U87EGFRvIII glioma-bearing mice is comparable, while the EGFR protein (wild type + vIII) levels are significantly higher in large EVs. Here we report for the first time a direct comparison of large and small EVs released by glioma U87EGFRvIII cells and from serum of U87EGFRvIII glioma-bearing mice. Both large and small EVs contain tumour-specific EGFRvIII mRNA and proteins and combining these platforms may be beneficial in detecting rare mutant events in circulating biofluids.

Hans Joachim Scherer and His Impact on the Diagnostic, Clinical, and Modern Research Aspects of Glial Tumors

The historical descriptions of glial tumors are often poorly understood and interpreted. The gross and histological depictions of glial tumors are often credited to Virchow, and while the first true histological description is truly his, gross descriptions can be traced back to the beginning of the 1800s, with their classification and histogenesis attributed to Percival Bailey and Harvey Cushing. Without any question, the most prominent and under-credited researcher in the field of glioma pathobiology was the German neuropathologist Hans Joachim Scherer. Despite the limited armamentarium available to him, his systematic approach led to conclusions, some of which have now been molecularly explained today while some are still being widely researched. Scherer defined pseudopalisadic necrosis as a pathognomonic feature of glioblastoma multiforme (GBM), as well as secondary features due to tumor growth, known collectively as secondary Scherer figures, for example, neuronal and vascular satellitosis, tract and subpial aggregation. All these features are key points in the modern histological diagnosis of glial tumors. Other contributions by Scherer include the definition of glomeruloid vascular proliferation and his conclusion that they are caused by vascular factors released by the tumor, decades before vascular endothelial growth factor and its receptors were discovered and their role in glioma evolution was established. Furthermore, he concluded that GBMs can arise de novo (primary) or from a preceding lower-grade glioma (secondary). All his contributions find their place in all modern aspects of glioma research, with some giving a simple explanation of the phenomena observed in glial tumors.

Extracellular vesicles as biomarkers and therapeutic targets for cancer

Extracellular vesicles (EVs) are small lipid membrane vesicles that are secreted from almost all kinds of cells into the extracellular space. EVs are widely accepted to be involved in various cellular processes; in particular, EVs derived from cancer cells have been reported to play important roles in modifying the tumor microenvironment and promoting tumor progression. In addition, EVs derived from cancer cells encapsulate various kinds of tumor-specific molecules, such as proteins and RNAs, which contribute to cancer malignancy. Therefore, the unveiling of the precise mechanism of intercellular communication via EVs in cancer patients will provide a novel strategy for cancer treatment. Furthermore, a focus on the contents of EVs could promote the use of EVs in body fluids as clinically useful diagnostic and prognostic biomarkers. In this review, we summarize the current research knowledge on EVs as biomarkers and therapeutic targets and discuss their potential clinical applications.