Extracellular Vesicles in Oncology: Progress and Pitfalls in the Methods of Isolation and Analysis

Recent advances in bioreceptor-based sensing for extracellular vesicle analysis

Extracellular vesicles (EVs) are nanoscale, membrane-bound structures secreted by various cell types into biofluids. They show great potential as biomarkers for disease diagnostics, owing to their ability to carry molecular cargo that reflects their cellular origin. However, the inherent heterogeneity of EVs in terms of size, composition, and source presents significant challenges for reliable detection and analysis. Recent advances in bioreceptor-based biosensor technologies provide promising solutions by offering high sensitivity and specificity in EV detection and characterization. These technologies address the limitations of conventional methods, such as ultracentrifugation and bulk analysis. Biosensors utilizing antibodies, aptamers, peptides, lectins, and molecularly imprinted polymers enable precise detection of EV subpopulations by targeting specific EV surface markers, including proteins, lipids, and glycans. Additionally, these biosensors support multiplexed and real-time analysis while preserving the structural integrity of EVs. This review highlights the transformative potential of combining modern biosensing tools with bioreceptor technologies to advance EV research and diagnostics, paving the way for innovations in disease diagnostics and therapeutic monitoring.

An Extracellular Vesicle (EV) Paper Strip for Rapid and Convenient Estimation of EV Concentration

Extracellular vesicles (EVs) have emerged as promising biomarkers and therapeutic agents, yet their quantification remains technically challenging due to the limitations of conventional methods. Here, a low-cost, fluorescence-based, paper-strip immunoassay is presented for rapid and semi-quantitative estimation of EV concentration, inspired by pH strips. The assay utilizes nitrocellulose membranes functionalized with capture antibodies (anti-CD63, CD9, CD81) and fluorescent dye (ExoBrite™) for EV detection. Systematic optimization of assay parameters-including dye application sequence, incubation time, antibody configuration, and dye concentration-revealed that labeling EVs with dye and incubating on the nitrocellulose paper strips for 20 min yielded the strongest and most reproducible signal. A 200× dilution of ExoBrite™ dye was determined to provide the best balance between sensitivity and specificity. A standard curve generated through twofold serial dilution of EVs from ovarian cancer cell culture medium confirmed a positive, concentration-dependent fluorescence response, establishing a usable dynamic range. Compared to existing technologies, this platform enables fast, simple-to-implement EV quantification using minimal sample volume and equipment. The simplicity and scalability of the method offer strong potential for use in clinical diagnostics and EV research applications.

Breaking barriers in targeted Therapy: Advancing exosome Isolation, Engineering, and imaging

Exosomes have emerged as promising tools for targeted drug delivery in biomedical applications and medicine. This review delves into the scientific advancements, challenges, and future prospects specifically associated with these technologies. In this work, we trace the research milestones that led to the discovery and characterization of exosomes and extracellular vesicles, and discuss strategies for optimizing the synthetic yield and the loading of these particles with various therapeutics. In addition, we report the current major issues affecting the field and hampering the clinical translation of these technologies. Highlighting the pivotal role of imaging techniques, we explore how they drive exosome therapy and development by offering insights into biodistribution and cellular trafficking dynamics. Methodologies for vesicle isolation, characterization, loading, and delivery mechanisms are thoroughly examined, alongside strategies aimed at enhancing their therapeutic efficacy. Special emphasis was dedicated to their therapeutic properties, particularly to their ability to deliver biologics into the cytoplasm. Furthermore, we delve into the intricate balance between surface modifications and targeting properties including also transgenic methods aimed at their functionalization and visualization within biological systems. This review underscores the transformative potential of these carriers in targeted drug delivery and identifies crucial areas for further research and clinical translation.

Circulating Extracellular Vesicles as Promising Biomarkers for Precession Diagnostics: A Perspective on Lung Cancer

Extracellular vesicles (EVs) have emerged as promising biomarkers in liquid biopsy, owing to their ubiquitous presence in bodily fluids and their ability to carry disease-related cargo. Recognizing their significance in disease diagnosis and treatment, substantial efforts have been dedicated to developing efficient methods for EV isolation, detection, and analysis. EVs, heterogeneous membrane-encapsulated vesicles secreted by all cells, contain bioactive substances capable of modulating recipient cell biology upon internalization, including proteins, lipids, DNA, and various RNAs. Their prevalence across bodily fluids has positioned them as pivotal mediators in physiological and pathological processes, notably in cancer, where they hold potential as straightforward tumor biomarkers. This review offers a comprehensive examination of advanced nanotechnology-based techniques for detecting lung cancer through EV analysis. It begins by providing a brief overview of exosomes and their role in lung cancer progression. Furthermore, this review explores the evolving landscape of EV isolation and cargo analysis, highlighting the importance of characterizing specific biomolecular signatures within EVs for improved diagnostic accuracy in lung cancer patients. Innovative strategies for enhancing the sensitivity and specificity of EV isolation and detection, including the integration of microfluidic platforms and multiplexed biosensing technologies are summarized. The discussion then extends to key challenges associated with EV-based liquid biopsies, such as the standardization of isolation and detection protocols and the establishment of robust analytical platforms for clinical translation. This review highlights the transformative impact of EV-based liquid biopsy in lung cancer diagnosis, heralding a new era of personalized medicine and improved patient care.

Advanced Enrichment and Separation of Extracellular Vesicles through the Super Absorbent Polymer Nanosieves

Extracellular vesicles (EVs) are promising therapeutic biomaterials capable of transferring their cargo molecules and external drugs to other cells in vivo and contain various biomarkers that can be used in liquid biopsies. The clinical application of EVs requires an efficient EV enrichment system for the large-scale production or high-throughput isolation of EVs from liquid samples, such as culture media, plant juices, and body fluids. However, current EV enrichment methods, such as ultrafiltration and ultracentrifugation, have limited applicability owing to their associated costs, inefficiency, scalability, and centrifugation time. Herein, we describe the development of a nanosieve based on a superabsorbent polymer for selective EV enrichment. The nanosieve absorbs small molecules while expelling large molecules, such as EVs, through the nanosized channels. We successfully concentrated EVs from clinical samples, such as serum and plasma, with superior cost and time efficiencies. The nanosieves did not interact with the EVs during enrichment, allowing the retention of their therapeutic functions. In addition, the nanosieve surface was specifically engineered to provide multifunctionality to effectively promote EV capture from bulk solutions. Overall, our nanosieve-based EV enrichment method is effective, time- and cost-saving, versatile, scalable, and modulable, and is an excellent option for EV production.

Stem Cell-Derived Exosomes: Natural Intercellular Messengers with Versatile Mechanisms for the Treatment of Diabetic Retinopathy

Diabetic retinopathy is one of the complications of diabetes mellitus that occurs in the early stages. It is a disease that has a serious impact, and may lead to blindness when the disease progresses to advanced stages. Currently, treatments for diabetic retinopathy are mainly limited to its advanced stages of the disease, being restricted to a single therapeutic mechanism. Stem cells hold the promise of regenerative therapy and have the potential to comprehensively improve diabetic retinopathy. However, direct stem cell therapy carries some risk of carcinogenesis. Exosomes secreted by stem cells have shown a similar overall improvement in disease as stem cells. Exosomes can carry a number of biologically active materials from donor cells to recipient cells or distant organs, regulating intercellular signaling. Exosomes have shown remarkable efficacy in alleviating oxidative stress, inhibiting inflammatory responses, suppressing angiogenesis, reducing apoptosis and protecting neural tissues. Currently, the experimental literature using stem cell exosomes in the treatment of diabetic retinopathy tends to converge on the above experimental results. With this in mind, we have chosen to explore exosomes in depth from a subtle molecular perspective. We will elaborate on this perspective in this paper and propose to advocate exosome therapy as one promising approach for the treatment of diabetic retinopathy to ameliorate the lesions through multiple mechanisms.

Biomarkers and diagnostic significance of non-coding RNAs in extracellular vesicles of pathologic pregnancy

Intercellular communication is an important mechanism for the development and maintenance of normal biological processes in all organs, including the female reproductive system. Extracellular vesicles, as important carriers of intercellular communication, contain a variety of biologically active molecules, such as mRNAs, miRNAs, lncRNAs, and circRNAs, which are involved in cell-to-cell exchanges as well as in many physiological and pathological processes in the body. Compared with biomarkers found in tissues or body fluids, extracellular vesicles show better stability due to the presence of their envelope membrane which prevents the degradation of the RNA message in their vesicles. Therefore, the genomic and proteomic information contained in extracellular vesicles can serve as important markers and potential therapeutic targets for female reproductive system-related diseases or placental function. Moreover, changes in the expression of non-coding RNAs (mainly miRNAs, lncRNAs, and circRNAs) in maternal extracellular vesicles can accurately and promptly reflect the progress of female reproductive system diseases. The aim of this review is to collect information on different types of non-coding RNAs with key molecular carriers in female pathologic pregnancies (preeclampsia and recurrent spontaneous abortion), so as to explore the relevant molecular mechanisms in female pathologic pregnancies and provide a theoretical basis for clinical research on the pathogenesis and therapeutic approaches of reproductive system diseases. The current state of the art of exosome isolation and extraction is also summarized.

Unveiling the multifaceted roles of microRNAs in extracellular vesicles derived from mesenchymal stem cells: implications in tumor progression and therapeutic interventions

Mesenchymal stem/stromal cells (MSCs) have the capacity to migrate to tumor sites in vivo and transmit paracrine signals by secreting extracellular vesicles (EVs) to regulate tumor biological behaviors. MSC-derived EVs (MSC-EVs) have similar tumor tropism and pro- or anti-tumorigenesis as their parental cells and exhibit superior properties in drug delivery. MSC-EVs can transfer microRNAs (miRNAs) to tumor cells, thereby manipulating multiple key cancer-related pathways, and further playing a vital role in the tumor growth, metastasis, drug resistance and other aspects. In addition, tumor cells can also influence the behaviors of MSCs in the tumor microenvironment (TME), orchestrating this regulatory process via miRNAs in EVs (EV-miRNAs). Clarifying the specific mechanism by which MSC-derived EV-miRNAs regulate tumor progression, as well as investigating the roles of EV-miRNAs in the TME will contribute to their applications in tumor pharmacotherapy. This article mainly reviews the multifaceted roles and mechanism of miRNAs in MSC-EVs affecting tumor progression, the crosstalk between MSCs and tumor cells caused by EV-miRNAs in the TME. Eventually, the clinical applications of miRNAs in MSC-EVs in tumor therapeutics are illustrated.

Most recent advances and applications of extracellular vesicles in tackling neurological challenges

Over the past few decades, there has been a notable increase in the global burden of central nervous system (CNS) diseases. Despite advances in technology and therapeutic options, neurological and neurodegenerative disorders persist as significant challenges in treatment and cure. Recently, there has been a remarkable surge of interest in extracellular vesicles (EVs) as pivotal mediators of intercellular communication. As carriers of molecular cargo, EVs demonstrate the ability to traverse the blood-brain barrier, enabling bidirectional communication. As a result, they have garnered attention as potential biomarkers and therapeutic agents, whether in their natural form or after being engineered for use in the CNS. This review article aims to provide a comprehensive introduction to EVs, encompassing various aspects such as their diverse isolation methods, characterization, handling, storage, and different routes for EV administration. Additionally, it underscores the recent advances in their potential applications in neurodegenerative disorder therapeutics. By exploring their unique capabilities, this study sheds light on the promising future of EVs in clinical research. It considers the inherent challenges and limitations of these emerging applications while incorporating the most recent updates in the field.

Comparison of the efficiency of ultrafiltration, precipitation, and ultracentrifugation methods for exosome isolation

Extracellular vesicles (EVs) are enclosed by a lipid-bilayer membrane and secreted by all types of cells. They are classified into three groups: apoptotic bodies, microvesicles, and exosomes. Exosomes play a number of important roles in the intercellular communication and crosstalk between tissues in the body. In this study, we use three common methods based on different principles for exosome isolation, namely ultrafiltration, precipitation, and ultracentrifugation. We use field emission scanning electron microscopy (FESEM) and dynamic light scattering (DLS) analyses for characterization of exosomes. The functionality and effect of isolated exosomes on the viability of hypoxic cells was investigated by alamarBlue and Flow-cytometry. The results of the FESEM study show that the ultrafiltration method isolates vesicles with higher variability of shapes and sizes when compared to the precipitation and ultracentrifugation methods. DLS results show that mean size of exosomes isolated by ultrafiltration, precipitation, and ultracentrifugation methods are 122, 89, and 60 nm respectively. AlamarBlue analysis show that isolated exosomes increase the viability of damaged cells by 11%, 15%, and 22%, respectively. Flow-cytometry analysis of damaged cells also show that these vesicles increase the content of live cells by 9%, 15%, and 20%, respectively. This study shows that exosomes isolated by the ultracentrifugation method are characterized by smaller size and narrow size distribution. Furthermore, more homogenous particles isolated by this method show increased efficiency of the protection of hypoxic cells in comparison with the exosomes isolated by the two other methods.

Harnessing tumor-derived exosomes: A promising approach for the expansion of clinical diagnosis, prognosis, and therapeutic outcome of prostate cancer

Prostate cancer is the second leading cause of men's death worldwide. Although early diagnosis and therapy for localized prostate cancer have improved, the majority of men with metastatic disease die from prostate cancer annually. Therefore, identification of the cellular-molecular mechanisms underlying the progression of prostate cancer is essential for overcoming controlled proliferation, invasion, and metastasis. Exosomes are small extracellular vesicles that mediate most cells' interactions and contain membrane proteins, cytosolic and nuclear proteins, extracellular matrix proteins, lipids, metabolites, and nucleic acids. Exosomes play an essential role in paracrine pathways, potentially influencing Prostate cancer progression through a wide variety of mechanisms. In the present review, we outline and discuss recent progress in our understanding of the role of exosomes in the Prostate cancer microenvironment, like their involvement in prostate cancer occurrence, progression, angiogenesis, epithelial-mesenchymal transition, metastasis, and drug resistance. We also present the latest findings regarding the function of exosomes as biomarkers, direct therapeutic targets in prostate cancer, and the challenges and advantages associated with using exosomes as natural carriers and in exosome-based immunotherapy. These findings are a promising avenue for the expansion of potential clinical approaches.

Exosomes and microvesicles in kidney transplantation: the long road from trash to gold

Kidney transplantation significantly enhances the survival rate and quality of life of patients with end-stage kidney disease. The ability to predict post-transplantation rejection events in their early phases can reduce subsequent allograft loss. Therefore, it is critical to identify biomarkers of rejection processes that can be acquired on routine analysis of samples collected by non-invasive or minimally invasive procedures. It is also important to develop new therapeutic strategies that facilitate optimisation of the dose of immunotherapeutic drugs and the induction of allograft immunotolerance. This review explores the challenges and opportunities offered by extracellular vesicles (EVs) present in biofluids in the discovery of biomarkers of rejection processes, as drug carriers and in the induction of immunotolerance. Since EVs are highly complex structures and their composition is affected by the parent cell's metabolic status, the importance of defining standardised methods for isolating and characterising EVs is also discussed. Understanding the major bottlenecks associated with all these areas will promote the further investigation of EVs and their translation into a clinical setting.

Cerebral microvascular endothelial cell-derived extracellular vesicles regulate blood - brain barrier function

Autoreactive T lymphocytes crossing the blood-brain barrier (BBB) into the central nervous system (CNS) play a crucial role in the initiation of demyelination and neurodegeneration in multiple sclerosis (MS). Recently, extracellular vesicles (EV) secreted by BBB endothelial cells (BBB-EC) have emerged as a unique form of cell-to-cell communication that contributes to cerebrovascular dysfunction. However, the precise impact of different size-based subpopulations of BBB-EC-derived EV (BBB-EV) on the early stages of MS remains unclear. Therefore, our objective was to investigate the content and function of distinct BBB-EV subpopulations in regulating BBB integrity and their role in T cell transendothelial migration, both in vitro and in vivo. Our study reveals that BBB-ECs release two distinct size based EV populations, namely small EV (sEV; 30-150 nm) and large EV (lEV; 150-300 nm), with a significantly higher secretion of sEV during inflammation. Notably, the expression patterns of cytokines and adhesion markers differ significantly between these BBB-EV subsets, indicating specific functional differences in the regulation of T cell migration. Through in vitro experiments, we demonstrate that lEV, which predominantly reflect their cellular source, play a major role in BBB integrity loss and the enhanced migration of pro-inflammatory Th1 and Th17.1 cells. Conversely, sEV appear to protect BBB function by inducing an anti-inflammatory phenotype in BBB-EC. These findings align with our in vivo data, where the administration of sEV to mice with experimental autoimmune encephalomyelitis (EAE) results in lower disease severity compared to the administration of lEV, which exacerbates disease symptoms. In conclusion, our study highlights the distinct and opposing effects of BBB-EV subpopulations on the BBB, both in vitro and in vivo. These findings underscore the need for further investigation into the diagnostic and therapeutic potential of BBB-EV in the context of MS.

Tumor-derived systems as novel biomedical tools-turning the enemy into an ally

Cancer is a complex illness that presents significant challenges in its understanding and treatment. The classic definition, "a group of diseases characterized by the uncontrolled growth and spread of abnormal cells in the body," fails to convey the intricate interaction between the many entities involved in cancer. Recent advancements in the field of cancer research have shed light on the role played by individual cancer cells and the tumor microenvironment as a whole in tumor development and progression. This breakthrough enables the utilization of the tumor and its components as biological tools, opening new possibilities. This article delves deeply into the concept of "tumor-derived systems", an umbrella term for tools sourced from the tumor that aid in combatting it. It includes cancer cell membrane-coated nanoparticles (for tumor theranostics), extracellular vesicles (for tumor diagnosis/therapy), tumor cell lysates (for cancer vaccine development), and engineered cancer cells/organoids (for cancer research). This review seeks to offer a complete overview of the tumor-derived materials that are utilized in cancer research, as well as their current stages of development and implementation. It is aimed primarily at researchers working at the interface of cancer biology and biomedical engineering, and it provides vital insights into this fast-growing topic.

Extracellular-Vesicle-Based Therapeutics in Neuro-Ophthalmic Disorders

Extracellular vesicles (EVs) have been recognized as promising candidates for developing novel therapeutics for a wide range of pathologies, including ocular disorders, due to their ability to deliver a diverse array of bioactive molecules, including proteins, lipids, and nucleic acids, to recipient cells. Recent studies have shown that EVs derived from various cell types, including mesenchymal stromal cells (MSCs), retinal pigment epithelium cells, and endothelial cells, have therapeutic potential in ocular disorders, such as corneal injury and diabetic retinopathy. EVs exert their effects through various mechanisms, including promoting cell survival, reducing inflammation, and inducing tissue regeneration. Furthermore, EVs have shown promise in promoting nerve regeneration in ocular diseases. In particular, EVs derived from MSCs have been demonstrated to promote axonal regeneration and functional recovery in various animal models of optic nerve injury and glaucoma. EVs contain various neurotrophic factors and cytokines that can enhance neuronal survival and regeneration, promote angiogenesis, and modulate inflammation in the retina and optic nerve. Additionally, in experimental models, the application of EVs as a delivery platform for therapeutic molecules has revealed great promise in the treatment of ocular disorders. However, the clinical translation of EV-based therapies faces several challenges, and further preclinical and clinical studies are needed to fully explore the therapeutic potential of EVs in ocular disorders and to address the challenges for their successful clinical translation. In this review, we will provide an overview of different types of EVs and their cargo, as well as the techniques used for their isolation and characterization. We will then review the preclinical and clinical studies that have explored the role of EVs in the treatment of ocular disorders, highlighting their therapeutic potential and the challenges that need to be addressed for their clinical translation. Finally, we will discuss the future directions of EV-based therapeutics in ocular disorders. Overall, this review aims to provide a comprehensive overview of the current state of the art of EV-based therapeutics in ophthalmic disorders, with a focus on their potential for nerve regeneration in ocular diseases.

Liposomes or Extracellular Vesicles: A Comprehensive Comparison of Both Lipid Bilayer Vesicles for Pulmonary Drug Delivery

The rapid and non-invasive pulmonary drug delivery (PDD) has attracted great attention compared to the other routes. However, nanoparticle platforms, like liposomes (LPs) and extracellular vesicles (EVs), require extensive reformulation to suit the requirements of PDD. LPs are artificial vesicles composed of lipid bilayers capable of encapsulating hydrophilic and hydrophobic substances, whereas EVs are natural vesicles secreted by cells. Additionally, novel LPs-EVs hybrid vesicles may confer the best of both. The preparation methods of EVs are distinguished from LPs since they rely mainly on extraction and purification, whereas the LPs are synthesized from their basic ingredients. Similarly, drug loading methods into/onto EVs are distinguished whereby they are cell- or non-cell-based, whereas LPs are loaded via passive or active approaches. This review discusses the progress in LPs and EVs as well as hybrid vesicles with a special focus on PDD. It also provides a perspective comparison between LPs and EVs from various aspects (composition, preparation/extraction, drug loading, and large-scale manufacturing) as well as the future prospects for inhaled therapeutics. In addition, it discusses the challenges that may be encountered in scaling up the production and presents our view regarding the clinical translation of the laboratory findings into commercial products.

The Role of Extracellular Vesicles in Diseases of the Ear, Nose, and Throat

Extracellular vesicles (EVs) are membranous nanoparticles produced by most cell types into the extracellular space and play an important role in cell-to-cell communication. Historically, EVs were categorized based on their methods of biogenesis and size into three groups: exosomes, microvesicles, and apoptotic bodies. Most recently, EV nomenclature has evolved to categorize these nanoparticles based on their size, surface markers, and/or the cell type which secreted them. Many techniques have been adopted in recent years which leverage these characteristics to isolate them from cell culture media and biological fluids. EVs carry various "cargo", including DNA, RNA, proteins, and small signaling molecules. After isolation, EVs can be characterized by various methods to analyze their unique cargo profiles which define their role in cell-to-cell communication, normal physiology, and disease progression. The study of EV cargo has become more common recently as we continue to delineate their role in various human diseases. Further understanding these mechanisms may allow for the future use of EVs as novel biomarkers and therapeutic targets in diseases. Furthermore, their unique cargo delivery mechanisms may one day be exploited to selectively deliver therapeutic agents and drugs. Despite the growing research interest in EVs, limited studies have focused on the role of EVs in the diseases of the ear, nose, and throat. In this review, we will introduce EVs and their cargo, discuss methods of isolation and characterization, and summarize the most up-to-date literature thus far into the role of EVs in diseases of the ear, nose, and throat.

Affinity-based isolation of extracellular vesicles and the effects on downstream molecular analysis

Extracellular vesicles (EVs) are transport vesicles with diameters ranging from 30 to 1000 nm, secreted by cells in both physiological and pathological conditions. By using the EV shuttling system, biomolecular cargo such as proteins and genetic materials travels between cells resulting in intercellular communication and epigenetic regulation. Because the presence of EVs and cargo molecules in body fluids can predict the state of the parental cells, EV isolation techniques from complex biofluids have been developed. Further exploration of EVs through downstream molecular analysis depends heavily on those isolation technologies. Methodologies based either on physical separation or on affinity binding have been used to isolate EVs. Affinity-based methods for EV isolation are known to produce highly specific and efficient isolation results. However, so far, there is a lack of literature summarizing these methods and their effects on downstream EV molecular analysis. In the present work, we reviewed recent efforts on developing affinity-based methods for the isolation of EVs, with an emphasis on comparing their effects on downstream analysis of EV molecular cargo. Antibody-based isolation techniques produce highly pure EVs, but the harsh eluents damage the EV structure, and some antibodies stay bound to the EVs after elution. Aptamer-based methods use relatively mild elution conditions and release EVs in their native form, but their isolation efficiencies need to be improved. The membrane affinity-based method and other affinity-based methods based on the properties of the EV lipid bilayer also isolate intact EVs, but they can also result in contaminants. From the perspective of affinity-based methods, we investigated the influence of the isolation methods of choice on downstream EV molecular analysis.

GFP-tagging of extracellular vesicles for rapid process development

Extracellular vesicles (EVs) act as nano-scale molecular messengers owing to their capacity to shuttle functional macromolecular cargo between cells. This intrinsic ability to deliver bioactive cargo has sparked great interest in the use of EVs as novel therapeutic delivery vehicles; investments totalling over $2 billion in 2020 alone were reported for therapeutic EVs. One of the bottlenecks facing the production of EVs is the lack of rapid and high throughput analytics and characterisation to aid process development. Here we have designed and engineered CHO cells to express GFP-tagged EVs via fusion to CD81. Moreover, we highlight the importance of parent cell characterisation to ensure lack of non-fused GFP for the effective use of this quantitative approach. The fluorescent nature of resulting vesicles allowed for rapid quantification of concentration and yield across the EV purification process. In this manner we deduced the degree of product loss by mass balance analysis of ultrafiltration processing and reconciled up to 97% of initial feed mass. The use of GFP-tagging allowed for straightforward monitoring of vesicle elution from chromatography separations and detection via western blotting. Collectively, this work illustrates the utility of GFP-tagged EVs as a quantitative and accessible tool for accelerated process development. This article is protected by copyright. All rights reserved.

Identifying the Efficacy of Extracellular Vesicles in Osteogenic Differentiation: An EV-Lution in Regenerative Medicine

Mesenchymal stromal cells (MSCs) have long been the focus for regenerative medicine and the restoration of damaged or aging cells throughout the body. However, the efficacy of MSCs in cell-based therapy still remains unpredictable and carries with it enumerable risks. It is estimated that only 3-10% of MSCs survive transplantation, and there remains undefined and highly variable heterogeneous biological potency within these administered cell populations. The mode of action points to secreted factors produced by MSCs rather than the reliance on engraftment. Hence harnessing such secreted elements as a replacement for live-cell therapies is attractive. Extracellular vesicles (EVs) are heterogenous lipid bounded structures, secreted by cells. They comprise a complex repertoire of molecules including RNA, proteins and other factors that facilitate cell-to-cell communication. Described as protected signaling centers, EVs can modify the cellular activity of recipient cells and are emerging as a credible alternative to cell-based therapies. EV therapeutics demonstrate beneficial roles for wound healing by preventing apoptosis, moderating immune responses, and stimulating angiogenesis, in addition to promoting cell proliferation and differentiation required for tissue matrix synthesis. Significantly, EVs maintain their signaling function following transplantation, circumventing the issues related to cell-based therapies. However, EV research is still in its infancy in terms of their utility as medicinal agents, with many questions still surrounding mechanistic understanding, optimal sourcing, and isolation of EVs for regenerative medicine. This review will consider the efficacy of using cell-derived EVs compared to traditional cell-based therapies for bone repair and regeneration. We discuss the factors to consider in developing productive lines of inquiry and establishment of standardized protocols so that EVs can be harnessed from optimal secretome production, to deliver reproducible and effective therapies.

Exosomal RNAs: Novel Potential Biomarkers for Diseases-A Review

Exosomes are a subset of nano-sized extracellular vesicles originating from endosomes. Exosomes mediate cell-to-cell communication with their cargos, which includes mRNAs, miRNAs, lncRNAs, and circRNAs. Exosomal RNAs have cell specificity and reflect the conditions of their donor cells. Notably, their detection in biofluids can be used as a diagnostic marker for various diseases. Exosomal RNAs are ideal biomarkers because their surrounding membranes confer stability and they are detectable in almost all biofluids, which helps to reduce trauma and avoid invasive examinations. However, knowledge of exosomal biomarkers remains scarce. The present review summarizes the biogenesis, secretion, and uptake of exosomes, the current researches exploring exosomal mRNAs, miRNAs, lncRNAs, and circRNAs as potential biomarkers for the diagnosis of human diseases, as well as recent techniques of exosome isolation.

Mesenchymal Stem Cell-Derived Extracellular Vesicle-Shuttled microRNA-302d-3p Represses Inflammation and Cardiac Remodeling Following Acute Myocardial Infarction

Our research intended to investigate the roles of mesenchymal stem cell (MSC)-derived extracellular vesicles (EVs) in acute myocardial infarction (AMI) via delivery of microRNA (miR)-302d-3p. AMI mouse models were established. EVs isolated from MSCs with miR-302d-3p mimic were injected near the infarct area or co-cultured with hypoxic cardiomyocytes to evaluate their effects. The expression of NF-κB pathway-related genes and inflammatory factors was determined. AMI mice exhibited downregulated miR-302d-3p and elevated MD2 and BCL6 levels. BCL6 was negatively targeted by miR-302d-3p and could bind to MD2 promoter to upregulate MD2 expression. MSCs-EVs, MSCs-EVs carrying miR-302d-3p, or BCL6 or MD2 silencing inactivated the NF-κB pathway and alleviated infarcted area, myocardial fibrosis, inflammation, apoptosis, and cardiac dysfunction in AMI mice. Besides, MSCs-EVs, MSCs-EVs carrying miR-302d-3p, or BCL6 or MD2 silencing diminished viability and inflammation but augmented apoptosis of hypoxic cardiomyocytes. Conclusively, MSCs-EVs carrying miR-302d-3p repressed inflammation and cardiac remodeling after AMI via BCL6/MD2/NF-κB axis.

Mutational status of plasma exosomal KRAS predicts outcome in patients with metastatic colorectal cancer

Liquid biopsy has become a useful alternative in metastatic colorectal cancer (mCRC) patients when tissue biopsy of metastatic sites is not feasible. In this study we aimed to investigate the clinical utility of circulating exosomes DNA in the management of mCRC patients. Exosomes level and KRAS mutational status in exosomal DNA was assesed in 70 mCRC patients and 29 CRC primary tumor and were analysed at different disease steps evaluating serial blood samples (240 blood samples). There was a significant correlation between the extension of disease and exosomes level and the resection of primary localized tumor was correlated with a decrease of KRAS G12V/ D copies and fractional abundance in metastatic disease. CEA expression and liver metastasis correlated with a higher number of KRAS G12V/D copies/ml and a higher fractional abundance; in the subgroup of mCRC patients eligible for surgery, the size of tumor and the radiological response were related to exosomes level but only the size was related to the number of KRAS WT copies; both KRAS wild-type and mutated levels were identified as a prognostic factor related to OS. Finally, we found that 91% of mutated mCRC patients became wild type after the first line chemotherapy but this status reverted in mutated one at progression in 80% of cases. In a prospective cohort of mCRC patients, we show how longitudinal monitoring using exosome-based liquid biopsy provides clinical information relevant to therapeutic stratification.

Toward the next-generation phyto-nanomedicines: cell-derived nanovesicles (CDNs) for natural product delivery

Phytochemicals are plant-derived bioactive compounds, which have been widely used for therapeutic purposes. Due to the poor water-solubility, low bioavailability and non-specific targeting characteristic, diverse classes of nanocarriers are utilized for encapsulation and delivery of bio-effective agents. Cell-derived nanovesicles (CDNs), known for exosomes or extracellular vesicles (EVs), are biological nanoparticles with multiple functions. Compared to the artificial counterpart, CDNs hold great potential in drug delivery given the higher stability, superior biocompatibility and the lager capability of encapsulating bioactive molecules. Here, we provide a bench-to-bedside review of CDNs-based nanoplatform, including the bio-origin, preparation, characterization and functionalization. Beyond that, the focus is laid on the therapeutic effect of CDNs-mediated drug delivery for natural products. The state-of-art development as well as some pre-clinical applications of using CDNs for disease treatment is also summarized. It is highly expected that the continuing development of CDNs-based delivery systems will further promote the clinical utilization and translation of phyto-nanomedicines.

Elucidating the Role of Extracellular Vesicles in Pancreatic Cancer

Simple Summary

Pancreatic cancer is one of the deadliest cancers worldwide. The chance of surviving more than 5 years after initial diagnosis is less than 10%. This is due to a lack of early diagnostics, where often at the time of initial detection the tumour has already spread to different parts of the body and has developed a propensity to develop drug resistance. Therefore, to tackle this devastating disease, it is necessary to identify the key players responsible for driving pancreatic cancer. Numerous studies have found that small bubble-like packages shed by cancer cells, called extracellular vesicles, play an important role in the progression of the disease. Our knowledge on how extracellular vesicles aid in the progression, spread and chemoresistance of pancreatic cancer is the focus of this review. Of note, these extracellular vesicles may serve as biomarkers for earlier detection of pancreatic cancer and could represent drug targets or drug delivery agents for the treatment of pancreatic cancer.

Abstract

Pancreatic cancer is one of the deadliest cancers worldwide, with a 5-year survival rate of less than 10%. This dismal survival rate can be attributed to several factors including insufficient diagnostics, rapid metastasis and chemoresistance. To identify new treatment options for improved patient outcomes, it is crucial to investigate the underlying mechanisms that contribute to pancreatic cancer progression. Accumulating evidence suggests that extracellular vesicles, including exosomes and microvesicles, are critical players in pancreatic cancer progression and chemoresistance. In addition, extracellular vesicles also have the potential to serve as promising biomarkers, therapeutic targets and drug delivery tools for the treatment of pancreatic cancer. In this review, we aim to summarise the current knowledge on the role of extracellular vesicles in pancreatic cancer progression, metastasis, immunity, metabolic dysfunction and chemoresistance, and discuss their potential roles as biomarkers for early diagnosis and drug delivery vehicles for treatment of pancreatic cancer.

Early Detection and Investigation of Extracellular Vesicles Biomarkers in Breast Cancer

Breast cancer (BC) is the most commonly diagnosed malignant tumor in women worldwide, and the leading cause of cancer death in the female population. The percentage of patients experiencing poor prognosis along with the risk of developing metastasis remains high, also affecting the resistance to current main therapies. Cancer progression and metastatic development are no longer due entirely to their intrinsic characteristics, but also regulated by signals derived from cells of the tumor microenvironment. Extracellular vesicles (EVs) packed with DNA, RNA, and proteins, are the most attractive targets for both diagnostic and therapeutic applications, and represent a decisive challenge as liquid biopsy-based markers. Here we performed a study based on a multiplexed phenotyping flow cytometric approach to characterize BC-derived EVs from BC patients and cell lines, through the detection of multiple antigens. Our data reveal the expression of EVs-related biomarkers derived from BC patient plasma and cell line supernatants, suggesting that EVs could be exploited for characterizing and monitoring disease progression.

Role of Extracellular Vesicle-Derived Biomarkers in Drug Metabolism and Disposition

Extracellular vesicles (EVs) are small, nonreplicating, lipid-encapsulated particles that contain a myriad of protein and nucleic acid cargo derived from their tissue of origin. The potential role of EV-derived biomarkers to the study of drug metabolism and disposition (DMD) has gained attention in recent years. The key trait that makes EVs an attractive biomarker source is their capacity to provide comparable insights to solid organ biopsy through an appreciably less invasive collection procedure. Blood-derived EVs exist as a heterogenous milieu of biologically distinct particles originating from different sources through different biogenesis pathways. Furthermore, blood (plasma and serum) contains an array of vesicular and nonvesicular contaminants, such as apoptotic bodies, plasma proteins, and lipoproteins that are routinely coisolated with EVs, albeit to a different extent depending on the isolation technique. The following minireview summarizes current studies reporting DMD biomarkers and addresses elements of EV isolation and quantification relevant to the application of EV-derived DMD biomarkers. Evidence based-best practice guidance aligned to Minimum Information for the Study of Extracellular Vesicles and EV-TRACK reporting standards are summarized in the context of DMD studies. SIGNIFICANCE STATEMENT: Extracellular vesicle (EV)-derived protein and nucleic acid cargo represent a potentially game-changing source of novel DMD biomarkers with the capacity to define within- and between-individual variability in drug exposure irrespective of etiology. However, robust translation of EV-derived biomarkers requires the generation of transparent reproducible evidence. This review outlines the critical elements of data generation and reporting relevant to achieving this evidence in a drug metabolism and disposition context.

Small extracellular vesicles in cancer

Extracellular vesicles (EV) are lipid-bilayer enclosed vesicles in submicron size that are released from cells. A variety of molecules, including proteins, DNA fragments, RNAs, lipids, and metabolites can be selectively encapsulated into EVs and delivered to nearby and distant recipient cells. In tumors, through such intercellular communication, EVs can regulate initiation, growth, metastasis and invasion of tumors. Recent studies have found that EVs exhibit specific expression patterns which mimic the parental cell, providing a fingerprint for early cancer diagnosis and prognosis as well as monitoring responses to treatment. Accordingly, various EV isolation and detection technologies have been developed for research and diagnostic purposes. Moreover, natural and engineered EVs have also been used as drug delivery nanocarriers, cancer vaccines, cell surface modulators, therapeutic agents and therapeutic targets. Overall, EVs are under intense investigation as they hold promise for pathophysiological and translational discoveries. This comprehensive review examines the latest EV research trends over the last five years, encompassing their roles in cancer pathophysiology, diagnostics and therapeutics. This review aims to examine the full spectrum of tumor-EV studies and provide a comprehensive foundation to enhance the field. The topics which are discussed and scrutinized in this review encompass isolation techniques and how these issues need to be overcome for EV-based diagnostics, EVs and their roles in cancer biology, biomarkers for diagnosis and monitoring, EVs as vaccines, therapeutic targets, and EVs as drug delivery systems. We will also examine the challenges involved in EV research and promote a framework for catalyzing scientific discovery and innovation for tumor-EV-focused research.

Bovine extracellular vesicles contaminate human extracellular vesicles produced in cell culture conditioned medium when 'exosome-depleted serum' is utilised

Extracellular vesicles (EVs) are important intercellular communication messengers. Half of the published studies in the field are in vitro cell culture based in which bovine serum in various concentrations and forms is used to facilitate the production of extracellular vesicles. 'Exosome depleted serum' is the type of bovine serum most widely used in the production of human EVs. Herein, we demonstrate that, despite the initial caution raised in 2014 about the persistence of bovine EVs, 'exosome depleted serum' was still used in 46% of publications on human or rodent EVs between 2015 and 2019. Using nanoparticle tracking analysis combined with detergent lysis of vesicles as well as bovine CD9 ELISA, we show that there were approximately 5.33 x 107/mL of bovine EVs remaining in the 'exosome depleted serum'. Importantly, the 'exosome depleted serum' was relatively enriched in small EVs by approximately 2.7-fold relative to the large EVs compared to that in the original serum. Specifically, the percentage of small EVs in total vesicles had increased from the original 48% in the serum before ultracentrifugation to 92% in the 'exosome depleted serum'. Furthermore, the pervasive bovine EVs carried over by the 'exosome depleted serum', even when the lowest concentration (0.5%) was used in cell culture, resulted in a significant contamination of human EVs in cell culture conditioned medium. Our findings indicate that the use 'exosome depleted serum' in cell culture-based studies may introduce artefacts into research examining the function of human and rodent EVs, in particular those involving EV miRNA. Thus, we appeal to the researchers in the EV field to seriously reconsider the practice of using 'exosome depleted serum' in the production of human and other mammalian EVs in vitro.

Adipose-Derived Stem Cell-Derived Extracellular Vesicles Inhibit the Fibrosis of Fibrotic Buccal Mucosal Fibroblasts via the MicroRNA-375/FOXF1 Axis

Oral submucous fibrosis (OSF) is a precancerous lesion. Adipose-derived stem cell- (ADSC-) derived extracellular vesicles (EVs) (ADSC-EVs) regulate multiple oral diseases. Hence, this study explored the mechanism of ADSC-EVs in OSF. ADSCs were transduced with microRNA- (miR-) 375 mimic. ADSC-EVs and miR-375-overexpressed ADSC-EVs (EVs-miR-375) were extracted and identified. miR-375 expression in EVs and fibrotic buccal mucosal fibroblasts (fBMFs) was detected. EV uptake by fBMFs was observed. The targeted relationship between miR-375 and forkhead box protein F1 (FOXF1) was predicted and verified. After EVs-miR-375 treatment or FOXF1 overexpression, fBMF cell proliferation, migration, invasion, and apoptosis were evaluated, and levels of apoptosis-related proteins (cleaved-caspase-3, Bax, and Bcl-2) and fibrosis markers (α-SMA, collagen I, and collagen III) were detected. Functional rescue experiments were further performed to verify the role of the miR-375/FOXF1 axis in OSF. miR-375 was notably upregulated in EVs-miR-375 and EVs-miR-375-treated fBMFs (all P < 0.001). ADSC-EVs carried miR-375 into fBMFs. fBMFs can internalize ADSC-EVs. EVs-miR-375 treatment markedly inhibited fBMF cell proliferation, migration, invasion, and fibrosis and promoted apoptosis (all P < 0.01). Moreover, miR-375 targeted FOXF1 in fBMFs. FOXF1 overexpression promoted fBMF cell biological behaviors and fibrosis, which were reversed after EVs-miR-375 treatment (P < 0.01 or P < 0.001). We highlighted that ADSC-EVs inhibited fBMF fibrosis and then suppressed OSF progression via the miR-375/FOXF1 axis.

Extracellular Vesicles as a Novel Liquid Biopsy-Based Diagnosis for the Central Nervous System, Head and Neck, Lung, and Gastrointestinal Cancers: Current and Future Perspectives

Simple Summary

To improve clinical outcomes, early diagnosis is mandatory in cancer patients. Several diagnostic approaches have been proposed, however, the main drawback relies on the invasive procedures required. Extracellular vesicles (EVs) are bilayer lipid membrane structures released by almost all cells and transferred to remote sites via the bloodstream. The observation that their cargo reflects the cell of origin has opened a new frontier for non-invasive biomarker discovery in oncology. Moreover, since EVs can be recovered from different body fluids, their impact as a Correctdiagnostic tool has gained particular interest. Hence, in the last decade, several studies using different biological fluids have been performed, showing the valuable contributions of EVs as tumour biomarkers, and their improved diagnostic power when combined with currently available tumour markers. In this review, the most relevant data on the diagnostic relevance of EVs, alone or in combination with the well-established tumour markers, are discussed.

Abstract

Early diagnosis, along with innovative treatment options, are crucial to increase the overall survival of cancer patients. In the last decade, extracellular vesicles (EVs) have gained great interest in biomarker discovery. EVs are bilayer lipid membrane limited structures, released by almost all cell types, including cancer cells. The EV cargo, which consists of RNAs, proteins, DNA, and lipids, directly mirrors the cells of origin. EVs can be recovered from several body fluids, including blood, cerebral spinal fluid (CSF), saliva, and Broncho-Alveolar Lavage Fluid (BALF), by non-invasive or minimally invasive approaches, and are therefore proposed as feasible cancer diagnostic tools. In this review, methodologies for EV isolation and characterization and their impact as diagnostics for the central nervous system, head and neck, lung, and gastrointestinal cancers are outlined. For each of these tumours, recent data on the potential clinical applications of the EV’s unique cargo, alone or in combination with currently available tumour biomarkers, have been deeply discussed.

Extracellular vesicles, the cornerstone of next-generation cancer diagnosis?

Cancer has risen up to be a major cause of mortality worldwide over the past decades. Despite advancements in cancer screening and diagnostics, a significant number of cancers are still diagnosed at a late stage with poor prognosis. Hence, the discovery of reliable and accurate methods to diagnose cancer early would be of great help in reducing cancer mortality. Extracellular vesicles (EVs) are phospholipid vesicles found in many biofluids and are released by almost all types of cells. In recent years, using EVs as cancer biomarkers has garnered attention as a novel technique of cancer diagnosis. Compared with traditional tissue biopsy, there are many advantages that this novel diagnostic tool presents - it is less invasive, detects early-stage asymptomatic cancers, and allows for monitoring of tumour progression. As such, EV biomarkers have great potential in improving the diagnostic accuracy of cancers and guiding subsequent therapeutic decisions. Efficient isolation and accurate characterization of EVs are essential for reliable outcomes of clinical application. However, these are complicated by the size and biomolecular diversity of EVs. In this review, we present an analysis and evaluation of the current techniques of EV isolation and characterization, as well as discuss the potential EV biomarkers for specific types of cancer. Taken together, EV biomarkers have a lot of potential as a novel method in cancer diagnostics and diagnosis. However, more work is still needed to streamline the purification, characterization and biomarker identification process to ensure optimal outcomes for patients.

Analysis of Amount, Size, Protein Phenotype and Molecular Content of Circulating Extracellular Vesicles Identifies New Biomarkers in Multiple Myeloma

INTRODUCTION

Extracellular vesicles (EVs) are naturally secreted cellular lipid bilayer particles, which carry a selected molecular content. Owing to their systemic availability and their role in tumor pathogenesis, circulating EVs (cEVs) can be a valuable source of new biomarkers useful for tumor diagnosis, prognostication and monitoring. However, a precise approach for isolation and characterization of cEVs as tumor biomarkers, exportable in a clinical setting, has not been conclusively established.

METHODS

We developed a novel and laboratory-made procedure based on a bench centrifuge step which allows the isolation of serum cEVs suitable for subsequent characterization of their size, amount and phenotype by nanoparticle tracking analysis, microscopy and flow cytometry, and for nucleic acid assessment by digital PCR.

RESULTS

Applied to blood from healthy subjects (HSs) and tumor patients, our approach permitted from a small volume of serum (i) the isolation of a great amount of EVs enriched in small vesicles free from protein contaminants; (ii) a suitable and specific cell origin identification of EVs, and (iii) nucleic acid content assessment. In clonal plasma cell malignancy, like multiple myeloma (MM), our approach allowed us to identify specific MM EVs, and to characterize their size, concentration and microRNA content allowing significant discrimination between MM and HSs. Finally, EV associated biomarkers correlated with MM clinical parameters.

CONCLUSION

Overall, our cEV based procedure can play an important role in malignancy biomarker discovery and then in real-time tumor monitoring using minimal invasive samples. From a practical point of view, it is smart (small sample volume), rapid (two hours), easy (no specific expertise required) and requirements are widely available in clinical laboratories.

Tumor-derived extracellular vesicles containing microRNA-1290 promote immune escape of cancer cells through the Grhl2/ZEB1/PD-L1 axis in gastric cancer

Gastric cancer (GC) is a highly prevalent malignancy featured by dismal oncological outcomes. Accumulating pieces of evidence have consensus over the therapeutic significance of extracellular vesicles (EVs) and its role in carcinogenesis. Here, we planned to uncover EVs' role in GC by shuttling microRNA-1290 (miR-1290) and to identify the possible molecular mechanism associated with Grhl2, PD-L1, and ZEB1. Grhl2 was under-expressed in GC tissues, exhibiting a negative correlation with PD-L1 expression. In addition, Grhl2 promoted T cell proliferation by down-regulating PD-L1 via inhibiting ZEB1, while miR-1290 was found to negatively regulate Grhl2. EVs were also isolated from GC cells or normal gastric epithelial cells and identified with the presence of EV markers. miR-1290 expression was determined to be enriched in the EVs derived from GC cells and observed to promote the suppressive action of GC cells on T cell activation by up-regulating PD-L1 via the Grhl2/ZEB1 pathway in the co-culture system of GC cells with or without treatment of EVs with T cells. Moreover, we also developed a mouse model of GC and injected the EVs derived from miR-1290-inhibitor-treated GC cells into the tumor-bearing mice for further validation of mechanism in vivo. Intriguingly, the pivotal role of EVs-shuttled miR-1290 as an oncomiR was demonstrated in vivo. Collectively, we found that miR-1290 in EVs secreted from GC cells contributed to immune escape through the Grhl2/ZEB1/PD-L1 axis.

Next-Generation Sequencing with Liquid Biopsies from Treatment-Naïve Non-Small Cell Lung Carcinoma Patients

Recently, the liquid biopsy (LB), a non-invasive and easy to repeat approach, has started to compete with the tissue biopsy (TB) for detection of targets for administration of therapeutic strategies for patients with advanced stages of lung cancer at tumor progression. A LB at diagnosis of late stage non-small cell lung carcinoma (NSCLC) is also being performed. It may be asked if a LB can be complementary (according to the clinical presentation or systematics) or even an alternative to a TB for treatment-naïve advanced NSCLC patients. Nucleic acid analysis with a TB by next-generation sequencing (NGS) is gradually replacing targeted sequencing methods for assessment of genomic alterations in lung cancer patients with tumor progression, but also at baseline. However, LB is still not often used in daily practice for NGS. This review addresses different aspects relating to the use of LB for NGS at diagnosis in advanced NSCLC, including its advantages and limitations.

An integrated workflow for biomarker development using microRNAs in extracellular vesicles for cancer precision medicine

EV-miRNAs are microRNA (miRNA) molecules encapsulated in extracellular vesicles (EVs), which play crucial roles in tumor pathogenesis, progression, and metastasis. Recent studies about EV-miRNAs have gained novel insights into cancer biology and have demonstrated a great potential to develop novel liquid biopsy assays for various applications. Notably, compared to conventional liquid biomarkers, EV-miRNAs are more advantageous in representing host-cell molecular architecture and exhibiting higher stability and specificity. Despite various available techniques for EV-miRNA separation, concentration, profiling, and data analysis, a standardized approach for EV-miRNA biomarker development is yet lacking. In this review, we performed a substantial literature review and distilled an integrated workflow encompassing important steps for EV-miRNA biomarker development, including sample collection and EV isolation, EV-miRNA extraction and quantification, high-throughput data preprocessing, biomarker prioritization and model construction, functional analysis, as well as validation. With the rapid growth of "big data", we highlight the importance of efficient mining of high-throughput data for the discovery of EV-miRNA biomarkers and integrating multiple independent datasets for in silico and experimental validations to increase the robustness and reproducibility. Furthermore, as an efficient strategy in systems biology, network inference provides insights into the regulatory mechanisms and can be used to select functionally important EV-miRNAs to refine the biomarker candidates. Despite the encouraging development in the field, a number of challenges still hinder the clinical translation. We finally summarize several common challenges in various biomarker studies and discuss potential opportunities emerging in the related fields.

Characterization of hyaluronan-coated extracellular vesicles in synovial fluid of patients with osteoarthritis and rheumatoid arthritis

BACKGROUND

Hyaluronic acid (HA) is the major extracellular matrix glycosaminoglycan with a reduced synovial fluid (SF) concentration in arthropathies. Cell-derived extracellular vesicles (EV) have also been proposed to contribute to pathogenesis in joint diseases. It has recently been shown that human SF contains HA-coated EV (HA-EV), but their concentration and function in joint pathologies remain unknown.

METHODS

The aim of the present study was to develop an applicable method based on confocal laser scanning microscopy (CLSM) and image analysis for the quantification of EV, HA-particles, and HA-EV in the SF of the human knee joint. Samples were collected during total knee replacement surgery from patients with end-stage rheumatoid arthritis (RA, n = 8) and osteoarthritis (OA, n = 8), or during diagnostic/therapeutic arthroscopy unrelated to OA/RA (control, n = 7). To characterize and quantify EV, HA-particles, and HA-EV, SF was double-stained with plasma membrane and HA probes and visualized by CLSM. Comparisons between the patient groups were performed with the Kruskal-Wallis analysis of variance.

RESULTS

The size distribution of EV and HA-particles was mostly similar in the study groups. Approximately 66% of EV fluorescence was co-localized with HA verifying that a significant proportion of EV carry HA. The study groups were clearly separated by the discriminant analysis based on the CLSM data. The intensities of EV and HA-particle fluorescences were lower in the RA than in the control and OA groups.

CONCLUSIONS

CLSM analysis offers a useful tool to assess HA-EV in SF samples. The altered EV and HA intensities in the RA SF could have possible implications for diagnostics and therapy.

Membrane Microvesicles as Potential Vaccine Candidates

The prevention and control of infectious diseases is crucial to the maintenance and protection of social and public healthcare. The global impact of SARS-CoV-2 has demonstrated how outbreaks of emerging and re-emerging infections can lead to pandemics of significant public health and socio-economic burden. Vaccination is one of the most effective approaches to protect against infectious diseases, and to date, multiple vaccines have been successfully used to protect against and eradicate both viral and bacterial pathogens. The main criterion of vaccine efficacy is the induction of specific humoral and cellular immune responses, and it is well established that immunogenicity depends on the type of vaccine as well as the route of delivery. In addition, antigen delivery to immune organs and the site of injection can potentiate efficacy of the vaccine. In light of this, microvesicles have been suggested as potential vehicles for antigen delivery as they can carry various immunogenic molecules including proteins, nucleic acids and polysaccharides directly to target cells. In this review, we focus on the mechanisms of microvesicle biogenesis and the role of microvesicles in infectious diseases. Further, we discuss the application of microvesicles as a novel and effective vaccine delivery system.

Current Status and Future Perspectives of Liquid Biopsy in Small Cell Lung Cancer

Approximately 19% of all cancer-related deaths are due to lung cancer, which is the leading cause of mortality worldwide. Small cell lung cancer (SCLC) affects approximately 15% of patients diagnosed with lung cancer. SCLC is characterized by aggressiveness; the majority of SCLC patients present with metastatic disease, and less than 5% of patients are alive at 5 years. The gold standard of SCLC treatment is platinum and etoposide-based chemotherapy; however, its effects are short. In recent years, treatment for SCLC has changed; new drugs have been approved, and new biomarkers are needed for treatment selection. Liquid biopsy is a non-invasive, rapid, repeated and alternative tool to the traditional tumor biopsy that could allow the most personalized medicine into the management of SCLC patients. Circulating tumor cells (CTCs) and cell-free DNA (cfDNA) are the most commonly used liquid biopsy biomarkers. Some studies have reported the prognostic factors of CTCs and cfDNA in SCLC patients, independent of the stage. In this review, we summarize the recent SCLC studies of CTCs, cfDNA and other liquid biopsy biomarkers, and we discuss the future utility of liquid biopsy in the clinical management of SCLC.

Roles of Exosomes in Ocular Diseases

Exosomes, nanoscale vesicles with a diameter of 30 to 150 nm, are composed of a lipid bilayer, protein, and genetic material. Exosomes are secreted by virtually all types of cells in the human body. They have key functions in cell-to-cell communication, immune regulation, inflammatory response, and neovascularization. Mounting evidence indicates that exosomes play an important role in various diseases, such as cancer, cardiovascular diseases, and brain diseases; however, the role that exosomes play in eye diseases has not yet been rigorously studied. This review covers current exosome research as it relates to ocular diseases including diabetic retinopathy, age-related macular degeneration, autoimmune uveitis, glaucoma, traumatic optic neuropathies, corneal diseases, retinopathy of prematurity, and uveal melanoma. In addition, we discuss recent advances in the biological functions of exosomes, focusing on the toxicity of exosomes and the use of exosomes as biomarkers and drug delivery vesicles. Finally, we summarize the primary considerations and challenges to be taken into account for the effective applications of exosomes.

Extracellular vesicles-encapsulated let-7i shed from bone mesenchymal stem cells suppress lung cancer via KDM3A/DCLK1/FXYD3 axis

Accumulating evidence has suggested that extracellular vesicles (EVs) play a crucial role in lung cancer treatment. Thus, we aimed to investigate the modulatory role of bone marrow mesenchymal stem cell (BMSC)-EV-derived let-7i and their molecular mechanism in lung cancer progression. Microarray-based analysis was applied to predict lung cancer-related miRNAs and their downstream genes. RT-qPCR and Western blot analyses were conducted to determine Let-7i, lysine demethylase 3A (KDM3A), doublecortin-like kinase 1 (DCLK1) and FXYD domain-containing ion transport regulator 3 (FXYD3) expressions, after which dual-luciferase reporter gene assay and ChIP assay were used to identify the relationship among them. After loss- and gain-of-function assays, the effects of let-7i, KDM3A, DCLK1 and FXYD3 on the biological characteristics of lung cancer cells were assessed. Finally, tumour growth in nude mice was assessed by xenograft tumours in nude mice. Bioinformatics analysis screened out the let-7i and its downstream gene, that is KDM3A. The findings showed the presence of a high expression of KDM3A and DCLK1 and reduced expression of let-7i and FXYD3 in lung cancer. KDM3A elevated DCLK1 by removing the methylation of H3K9me2. Moreover, DCLK1 suppressed the FXYD3 expression. BMSC-EV-derived let-7i resulted in the down-regulation of KDM3A expression and reversed its promoting role in lung cancer development. Consistently, in vivo experiments in nude mice also confirmed that tumour growth was suppressed by the BMSC-EV-derived let-7i. In conclusion, our findings demonstrated that the BMSC-EV-derived let-7i possesses an inhibitory role in lung cancer progression through the KDM3A/DCLK1/FXYD3 axis, suggesting a new molecular target for lung cancer treatment.

Microfluidic Raman biochip detection of exosomes: a promising tool for prostate cancer diagnosis

Tumor-derived exosomes, which contain RNA, DNA, and proteins, are a potentially rich non-invasive source of biomarkers. However, no efficient isolation or detection methods are yet available. Here, we developed a microfluidic Raman biochip designed to isolate and analyze exosomes in situ. Anti-CD63 magnetic nanoparticles were used to enrich exosomes through mixing channels of a staggered triangular pillar array. EpCAM-functionalized Raman-active polymeric nanomaterials (Raman beads) allow rapid analysis of exosome samples within 1 h, with a quantitative signal at 2230 cm-1. The limit of detection of this biochip approaches 1.6 × 102 particles per mL with 20 μL samples. The newly developed biochip assay was successfully applied in the determination of exosomes from clinical serum samples. Thus, this novel device may have potential as a clinical exosome analysis tool for prostate cancer.

A Protocol for Cancer-Related Mutation Detection on Exosomal DNA in Clinical Application

Background

Recently, some genomic mutations in exosomal DNA have been found to be related to disease progress and clinical outcomes of patients in several cancers. Unfortunately, the methods for exosome isolation and exosomal DNA analysis are still lack of relevant research to ensure their optimal performance and the comparability. Here we aim to establish a protocol for cancer-related mutation detection on exosomal DNA in clinical application.

Methods

Taking KRAS mutation in pancreatic cancer as an example, we tested whether the types of blood samples, the potential factors in the courses of exosome isolation and exosomal DNA preparation, as well as the detail in mutation detection by droplet digital PCR (ddPCR) could influence the exosomal DNA analysis.

Results

We found that the concentration of exosomal DNA from serum was higher than that from plasma, whereas the mutant allele fraction (MAF) of KRAS in serum-derived exosomal DNA was obviously lower. The membrane-based method for exosome isolation showed no evident difference in both exosomal DNA yield and KRAS MAF from the classical ultracentrifugation method. DNase I pretreatment on exosomes could remove the wild-type DNA outside of exosomes and increase the KRAS MAF. PBS might interfere with the effect of DNase I and should not be recommended as resuspension buffer for exosomes if the subsequent experiments would be done with exosomal DNA. Besides, the denaturation of exosomal DNA before droplet generation during ddPCR could effectively improve the total KRAS copy number and mutation-positive droplet number.

Conclusion

This study provides some methodological evidences for the selection of the optimal experimental conditions in exosomal DNA analysis. We also suggest a protocol for mutation detection on exosomal DNA, which might be suitable for the clinical testing and could be helpful to the comparison of results from different laboratories.

Use of Nanosphere Self-Assembly to Pattern Nanoporous Membranes for the Study of Extracellular Vesicles

Nanoscale biocomponents naturally released by cells, such as extracellular vesicles (EVs), have recently gained interest due to their therapeutic and diagnostic potential. Membrane based isolation and co-culture systems have been utilized in an effort to study EVs and their effects. Nevertheless, improved platforms for the study of small EVs are still needed. Suitable membranes, for isolation and co-culture systems, require pore sizes to reach into the nanoscale. These pore sizes cannot be achieved through traditional lithographic techniques and conventional thick nanoporous membranes commonly exhibit low permeability. Here we utilized nanospheres, similar in size and shape to the targeted small EVs, as patterning features for the fabrication of freestanding SiN membranes (120 nm thick) released in minutes through a sacrificial ZnO layer. We evaluated the feasibility of separating subpopulation of EVs based on size using these membranes. The membrane used here showed an effective size cut-off of 300 nm with the majority of the EVs ≤200 nm. This work provides a convenient platform with great potential for studying subpopulations of EVs.

Low-Vacuum Filtration as an Alternative Extracellular Vesicle Concentration Method: A Comparison with Ultracentrifugation and Differential Centrifugation

Recent years have brought great focus on the development of drug delivery systems based on extracellular vesicles (EVs). Considering the possible applications of EVs as drug carriers, the isolation process is a crucial step. To solve the problems involved in EV isolation, we developed and validated a new EV isolation method—low-vacuum filtration (LVF)—and compared it with two commonly applied procedures—differential centrifugation (DC) and ultracentrifugation (UC). EVs isolated from endothelial cell culture media were characterized by (a) Transmission Electron Microscopy (TEM), (b) Nanoparticle Tracking Analysis (NTA), (c) Western blot and (d) Attenuated Total Reflection Fourier-Transform Infrared Spectroscopy (ATR-FTIR). Additionally, the membrane surface was imaged with Environmental Scanning Electron Microscopy (ESEM). We found that LVF was a reproducible and efficient method for EV isolation from conditioned media. Additionally, we observed a correlation between ATR-FTIR spectra quality and EV and protein concentration. ESEM imaging confirmed that the actual pore diameter was close to the values calculated theoretically. LVF is an easy, fast and inexpensive EV isolation method that allows for the isolation of both ectosomes and exosomes from high-volume sources with good repeatability. We believe that it could be an efficient alternative to commonly applied methods.

Measuring Extracellular Vesicles by Conventional Flow Cytometry: Dream or Reality?

Intense research is being conducted using flow cytometers available in clinically oriented laboratories to assess extracellular vesicles (EVs) surface cargo in a variety of diseases. Using EVs of various sizes purified from the HT29 human colorectal adenocarcinoma cell line, we report on the difficulty to assess small and medium sized EVs by conventional flow cytometer that combines light side scatter off a 405 nm laser with the fluorescent signal from the EVs general labels Calcein-green and Calcein-violet, and surface markers. Small sized EVs (~70 nm) immunophenotyping failed, consistent with the scarcity of monoclonal antibody binding sites, and were therefore excluded from further investigation. Medium sized EVs (~250 nm) immunophenotyping was possible but their detection was plagued by an excess of coincident particles (swarm detection) and by a high abort rate; both factors affected the measured EVs concentration. By running samples containing equal amounts of Calcein-green and Calcein-violet stained medium sized EVs, we found that swarm detection produced false double positive events, a phenomenon that was significantly reduced, but not totally eliminated, by sample dilution. Moreover, running highly diluted samples required long periods of cytometer time. Present findings raise questions about the routine applicability of conventional flow cytometers for EV analysis.

Liquid Biopsy is Instrumental for 3PM Dimensional Solutions in Cancer Management

One in every four deaths is due to cancer in Europe. In view of its increasing incidence, cancer became the leading cause of death and disease burden in Denmark, France, the Netherlands, and the UK. Without essential improvements in cancer prevention, an additional 775,000 cases of annual incidence have been prognosed until 2040. Between 1995 and 2018, the direct costs of cancer doubled from EUR 52 billion to EUR 103 billion in Europe, and per capita health spending on cancer increased by 86% from EUR 105 to EUR 195 in general, whereby Austria, Germany, Switzerland, Benelux, and France spend the most on cancer care compared to other European countries. In view of the consequent severe socio-economic burden on society, the paradigm change from a reactive to a predictive, preventive, and personalized medical approach in the overall cancer management is essential. Concepts of predictive, preventive, and personalized medicine (3PM) demonstrate a great potential to revise the above presented trends and to implement cost-effective healthcare that benefits the patient and society as a whole. At any stage, application of early and predictive diagnostics, targeted prevention, and personalization of medical services are basic pillars making 3PM particularly attractive for the patients as well as ethical and cost-effective healthcare. Optimal 3PM approach requires novel instruments such as well-designed liquid biopsy application. This review article highlights current achievements and details liquid biopsy approaches specifically in cancer management. 3PM-relevant expert recommendations are provided.

Lead Compounds in the Context of Extracellular Vesicle Research

Studies of small extracellular vesicles (sEVs), known as exosomes, have been flourishing in the last decade with several achievements, from advancing biochemical knowledge to use in biomedical applications. Physiological changes of sEVs due to the variety of cargos they carry undoubtedly leave an impression that affects the understanding of the mechanism underlying disease and the development of sEV-based shuttles used for treatments and non-invasive diagnostic tools. Indeed, the remarkable properties of sEVs are based on their nature, which helps shield them from recognition by the immune system, protects their payload from biochemical degradation, and contributes to their ability to translocate and convey information between cells and their inherent ability to target disease sites such as tumors that is valid for sEVs derived from cancer cells. However, their transport, biogenesis, and secretion mechanisms are still not thoroughly clear, and many ongoing investigations seek to determine how these processes occur. On the other hand, lead compounds have been playing critical roles in the drug discovery process and have been recently employed in studies of the biogenesis and secretion of sEVs as external agents, affecting sEV release and serving as drug payloads in sEV drug delivery systems. This article gives readers an overview of the roles of lead compounds in these two research areas of sEVs, the rising star in studies of nanoscale medicine.