Microfluidic filtration system to isolate extracellular vesicles from blood

Extracellular vesicles

Extracellular vesicles (EVs) encompass a diverse array of membrane-bound organelles released outside cells in response to developmental and physiological cell needs. EVs play important roles in remodeling the shape and content of differentiating cells and can rescue damaged cells from toxic or dysfunctional content. EVs can send signals and transfer metabolites between tissues and organisms to regulate development, respond to stress or tissue damage, or alter mating behaviors. While many EV functions have been uncovered by characterizing ex vivo EVs isolated from body fluids and cultured cells, research using the nematode Caenorhabditis elegans has provided insights into the in vivo functions, biogenesis, and uptake pathways. The C. elegans EV field has also developed methods to analyze endogenous EVs within the organismal context of development and adult physiology in free-living, behaving animals. In this review, we summarize major themes that have emerged for C. elegans EVs and their relevance to human health and disease. We also highlight the diversity of biogenesis mechanisms, locations, and functions of worm EVs and discuss open questions and unexplored topics tenable in C. elegans, given the nematode model is ideal for light and electron microscopy, genetic screens, genome engineering, and high-throughput omics.

Recent progress in engineered extracellular vesicles and their biomedical applications

AIMS

To present the recent update on the isolation, engineering techniques for extracellular vesicles, limitations associated with different isolation techniques, different biomedical applications, and challenges of engineered extracellular vesicles for the benefit of researchers from academic, industry, etc. MATERIALS AND METHODS: Peer-reviewed articles from most recognized journals were collected, and presented information was analyzed to discuss collection, chemical, electroporation, cellular, and membrane surface engineering to design extracellular vesicles for various therapeutic applications. In addition, we present the applications and limitations of techniques for the collection of extracellular vesicles.

KEY FINDINGS

There is a need for isolation techniques with the gold standard. However, advanced extracellular vesicle isolation techniques showed improved recovery, and purity of extracellular vesicles. Tumor therapy is a major part of the therapy section that illustrates the role of engineered extracellular vesicles in synergetic therapy such as phototherapy, theragnostic, and delivery of genetic materials. In addition, extracellular vesicles have shown their potential in the treatment of retinal disorders, neurodegenerative disease, tuberculosis, osteoporosis, inflammatory bowel disease, vaccine production, and wound healing.

SIGNIFICANCE

Engineered extracellular vesicles can deliver cargo to the specific cells, elicit an immune response and could be used for the development of the vaccines in the future. However, the progress is at the initial stage. Overall, this review will provide a comprehensive understanding and could serve as a reference for researchers in the clinical translation of engineered extracellular vesicles in different biomedical fields.

Composition, functions, and applications of exosomal membrane proteins

Exosomes play a crucial role in various biological processes, such as human development, immune responses, and disease occurrence. The membrane proteins on exosomes are pivotal factors for their biological functionality. Currently, numerous membrane proteins have been identified on exosome membranes, participating in intercellular communication, mediating target cell recognition, and regulating immune processes. Furthermore, membrane proteins from exosomes derived from cancer cells can serve as relevant biomarkers for early cancer diagnosis. This article provides a comprehensive review of the composition of exosome membrane proteins and their diverse functions in the organism's biological processes. Through in-depth exploration of exosome membrane proteins, it is expected to offer essential foundations for the future development of novel biomedical diagnostics and therapies.

Natural killer cell-derived exosome-based cancer therapy: from biological roles to clinical significance and implications

Natural killer (NK) cells are important immune cells in the organism and are the third major type of lymphocytes besides T cells and B cells, which play an important function in cancer therapy. In addition to retaining the tumor cell killing function of natural killer cells, natural killer cell-derived exosomes cells also have the characteristics of high safety, wide source, easy to preserve and transport. At the same time, natural killer cell-derived exosomes are easy to modify, and the engineered exosomes can be used in combination with a variety of current cancer therapies, which not only enhances the therapeutic efficacy, but also significantly reduces the side effects. Therefore, this review summarizes the source, isolation and modification strategies of natural killer cell-derived exosomes and the combined application of natural killer cell-derived engineered exosomes with other antitumor therapies, which is expected to accelerate the clinical translation process of natural killer cell-derived engineered exosomes in cancer therapy.

Small extracellular vesicles: Multi-functional aspects in non-small cell lung carcinoma

Extracellular vesicles (EVs) impact normal and pathological cellular signaling through bidirectional trafficking. Exosomes, a subset of EVs possess biomolecules including proteins, lipids, DNA fragments and various RNA species reflecting a speculum of their parent cells. The involvement of exosomes in bidirectional communication and their biological constituents substantiate its role in regulating both physiology and pathology, including multiple cancers. Non-small cell lung cancer (NSCLC) is the most common lung cancers (85%) with high incidence, mortality and reduced overall survival. Lack of efficient early diagnostic and therapeutic tools hurdles the management of NSCLC. Interestingly, the exosomes from body fluids similarity with parent cells or tissue offers a potential future multicomponent tool for the early diagnosis of NSCLC. The structural twinning of exosomes with a cell/tissue and the competitive tumor derived exosomes in tumor microenvironment (TME) promotes the unpinning horizons of exosomes as a drug delivery, vaccine, and therapeutic agent. Exosomes in clinical point of view assist to trace: acquired resistance caused by various therapeutic agents, early diagnosis, progression, and surveillance. In an integrated approach, EV biomarkers offer potential cutting-edge techniques for the detection and diagnosis of cancer, though the purification, characterization, and biomarker identification processes for the translational research regarding EVs need further optimization.

Recent research on material-based methods for isolation of extracellular vesicles

Extracellular vesicles (EVs) are nanoparticles secreted by cells with a closed phospholipid bilayer structure, which can participate in various physiological and pathological processes and have significant clinical value in disease diagnosis, targeted therapy and prognosis assessment. EV isolation methods currently include differential ultracentrifugation, ultrafiltration, size exclusion chromatography, immunoaffinity, polymer co-precipitation and microfluidics. In addition, material-based biochemical or biophysical approaches relying on intrinsic properties of the material or its surface-modified functionalized monomers, demonstrated unique advantages in the efficient isolation of EVs. In order to provide new ideas for the subsequent development of material-based EV isolation methods, this review will focus on the principle, research status and application prospects of material-based EV isolation methods based on different material carriers and functional monomers.

Efficient EVs separation and detection by an alumina-nanochannel-array-membrane integrated microfluidic chip and an antibody barcode biochip

BACKGROUND

Small endosome-derived lipid nanovesicles (30-200 nm) are actively secreted by living cells and serve as pivotal biomarkers for early cancer diagnosis. However, the study of extracellular vesicles (EVs) requires isolation and purification from various body fluids. Although traditional EVs isolation and detection technologies are mature, they usually require large amount of sample, consumes long-time, and have relatively low-throughput. How to efficiently isolate, purify and detect these structurally specific EVs from body fluids with high-throughput remains a great challenge in in vitro diagnostics and clinical research.

RESULTS

Herein, we suggest a nanosized microfluidic device for efficient and economical EVs filtration based on an alumina nanochannel array membrane. We evaluated the filtration device performance of alumina membranes with different diameters and found that an optimized chamber array with a hydrophilic-treated channel diameter of 90 nm could realize a filtration efficiency of up to 82% without any assistance from chemical or physical separation methods. Importantly, by integrating meticulously designed multichannel microfluidic biochips, EVs can be captured in-situ and monitored by antibody barcode biochip. The proposed filtration chip together with the high-throughput detection chip were capable of filtration of a few tens of μL samples and recognition of different phonotypes. The practical filtration and detection of EVs from clinical samples demonstrated the high performance of the device.

SIGNIFICANT

Overall, this work provides a cost-effective, highly efficient and automated EVs filtration chip and detection dual-function integrated chip platform, which can directly separate EVs from serum or cerebrospinal fluid with an efficiency of 82% and conduct in-situ detection. This small fluidic device can provide a powerful tool for highly efficient identifying and analyzing EVs, presenting great application potential in clinical detection.

An overview of challenges associated with exosomal miRNA isolation toward liquid biopsy-based ovarian cancer detection

As one of the deadliest gynaecological cancers, ovarian cancer has been on the list. With lesser-known symptoms and lack of an accurate detection method, it is still difficult to catch it early. In terms of both the diagnosis and outlook for cancer, liquid biopsy has come a long way with significant advancements. Exosomes, extracellular components commonly shed by cancerous cells, are nucleic acid-rich particles floating in almost all body fluids and hold enormous promise, leading to minimallyinvasive molecular diagnostics. They have been shown as potential biomarkers in liquid biopsy, being implicated in tumour growth and metastasis. In order to address the drawbacks of ovarian cancer tumor heterogeneity, a liquid biopsy-based approach is being investigated by detecting cell-free nucleic acids, particularly non-coding RNAs, having the advantage of being less invasive and more prominent in nature. microRNAs are known to actively contribute to cancer development and their existence inside exosomes has also been made quite apparent which can be leveraged to diagnose and treat the disease. Extraction of miRNAs and exosomes is an arduous execution, and while other approaches have been investigated, none have produced results that are as encouraging due to limits in time commitment, yield, and, most significantly, damage to the exosomal structure resulting discrepancies in miRNA-based expression profiling for disease diagnosis. We have briefly outlined and reviewed the difficulties with exosome isolation techniques and the need for their standardization. The several widely used procedures and their drawbacks in terms of the exosomal purity they may produce have also been outlined.

Unveiling clinical applications of bacterial extracellular vesicles as natural nanomaterials in disease diagnosis and therapeutics

Bacterial extracellular vesicles (BEVs) are naturally occurring bioactive membrane-bound nanoparticles released by both gram-negative and gram-positive bacterial species, exhibiting a multifaceted role in mediating host-microbe interactions across various physiological conditions. Increasing evidence supports BEVs as essential mediators of cell-to-cell communicaiton, influencing bacterial pathogenicity, disease mechanisms, and modulating the host immune response. However, the extent to which these BEV-mediated actions can be leveraged to predict disease onset, guide treatment strategies, and determine clinical outcomes remains uncertain, particularly in terms of their clinical translation potentials. This review briefly describes BEV biogenesis and their internalisation by recipient cells and summarises methods for isolation and characterization, essential for understanding their composition and cargo. Further, it discusses the potential of biofluid-associated BEVs as biomarkers for various diseases, spanning both cancer and non-cancerous conditions. Following this, we outline the ongoing human clinical trials of using BEVs for vaccine development. In addition to disease diagnostics, this review explores the emerging research of using natural or engineered BEVs as smart nanomaterials for applications in anti-cancer therapy and bone regeneration. This discussion extends to key factors for unlocking the clinical potential of BEVs, such as standardization of BEV isolation and characterisation, as well as other hurdles in translating these findings to the clinical setting. We propose that addressing these hurdles through collaborative research efforts and well-designed clinical trials holds the key to fully harnessing the clinical potential of BEVs. As this field advances, this review suggests that BEV-based nanomedicine has the potential to revolutionize disease management, paving the way for innovative diagnosis, therapeutics, and personalized medicine approaches. STATEMENT OF SIGNIFICANCE: Extracellular vesicles (EVs) from both host cells and bacteria serve as multifunctional biomaterials and are emerging in the fields of biomedicine, bioengineering, and biomaterials. However, the majority of current studies focus on host-derived EVs, leaving a gap in comprehensive research on bacteria-derived EVs (BEVs). Although BEVs offer an attractive option as nanomaterials for drug delivery systems, their unique nanostructure and easy-to-modify functions make them a potential method for disease diagnosis and treatment as well as vaccine development. Our work among the pioneering studies investigating the potential of BEVs as natural nanobiomaterials plays a crucial role in both understanding the development of diseases and therapeutic interventions.

Exosome Isolation and Detection: From Microfluidic Chips to Nanoplasmonic Biosensor

Exosomes are becoming more widely acknowledged as significant circulating indicators for the prognosis and diagnosis of cancer. Circulating exosomes are essential to the development and spread of cancer, according to a growing body of research. Using existing technology, characterizing exosomes is quite difficult. Therefore, a direct, sensitive, and targeted approach to exosome detection will aid in illness diagnosis and prognosis. The review discusses the new strategies for exosome isolation and detection technologies from microfluidic chips to nanoplasmonic biosensors, analyzing the advantages and limitations of these new technologies. This review serves researchers to better understand exosome isolation and detection methods and to help develop better exosome isolating and detecting devices for clinical applications.

A Novel Microfluidic Strategy for Efficient Exosome Separation via Thermally Oxidized Non-Uniform Deterministic Lateral Displacement (DLD) Arrays and Dielectrophoresis (DEP) Synergy

Exosomes, with diameters ranging from 30 to 150 nm, are saucer-shaped extracellular vesicles (EVs) secreted by various type of human cells. They are present in virtually all bodily fluids. Owing to their abundant nucleic acid and protein content, exosomes have emerged as promising biomarkers for noninvasive molecular diagnostics. However, the need for exosome separation purification presents tremendous technical challenges due to their minuscule size. In recent years, microfluidic technology has garnered substantial interest as a promising alternative capable of excellent separation performance, reduced reagent consumption, and lower overall device and operation costs. In this context, we hereby propose a novel microfluidic strategy based on thermally oxidized deterministic lateral displacement (DLD) arrays with tapered shapes to enhance separation performance. We have achieved more than 90% purity in both polystyrene nanoparticle and exosome experiments. The use of thermal oxidation also significantly reduces fabrication complexity by avoiding the use of high-precision lithography. Furthermore, in a simulation model, we attempt to integrate the use of dielectrophoresis (DEP) to overcome the size-based nature of DLD and distinguish particles that are close in size but differ in biochemical compositions (e.g., lipoproteins, exomeres, retroviruses). We believe the proposed strategy heralds a versatile and innovative platform poised to enhance exosome analysis across a spectrum of biochemical applications.

Extracellular vesicle biomarkers in ocular fluids associated with ophthalmic diseases

Extracellular vesicles (EVs) are released as highly stable lipid bilayer particles carrying proteins, lipids, glycans and miRNAs. The contents of EVs vary based on the cellular origin, biogenesis route and the functional state of the cell suggesting certain diseased conditions. A growing body of evidence show that EVs carry important molecules implicated in the development and progression of ophthalmic diseases. EVs associated with ophthalmic diseases are mainly carried by one of the three ocular biofluids which include tears, aqueous humor and vitreous humor. This review summarizes the list of EV derived biomarkers identified thus far in ocular fluids for ophthalmic disease diagnosis. Further, the methods used for sample collection, sample volume and the sample numbers used in these studies have been highlighted. Emphasis has been given to describe the EV isolation and the characterization methods used, EV size profiled and the EV concentrations analyzed by these studies, thus providing a roadmap for future EV biomarker studies in ocular fluids.

Engineered exosomes in emerging cell-free therapy

The discovery and use of exosomes ushered in a new era of cell-free therapy. Exosomes are a subgroup of extracellular vesicles that show great potential in disease treatment. Engineered exosomes. with their improved functions have attracted intense interests of their application in translational medicine research. However, the technology of engineering exosomes still faces many challenges which have been the great limitation for their clinical application. This review summarizes the current status of research on engineered exosomes and the difficulties encountered in recent years, with a view to providing new approaches and ideas for future exosome modification and new drug development.

Unlocking the potential of exosomes in cancer research: A paradigm shift in diagnosis, treatment, and prevention

Exosomes, which are tiny particles released by cells, have the ability to transport various molecules, including proteins, lipids, and genetic material containing non-coding RNAs (ncRNAs). They are associated with processes like cancer metastasis, immunity, and tissue repair. Clinical trials have shown exosomes to be effective in treating cancer, inflammation, and chronic diseases. Mesenchymal stem cells (MSCs) and dendritic cells (DCs) are common sources of exosome production. Exosomes have therapeutic potential due to their ability to deliver cargo, modulate the immune system, and promote tissue regeneration. Bioengineered exosomes could revolutionize disease treatment. However, more research is needed to understand exosomes in tumor growth and develop new therapies. This paper provides an overview of exosome research, focusing on cancer and exosome-based therapies including chemotherapy, radiotherapy, and vaccines. It explores exosomes as a drug delivery system for cancer therapy, highlighting their advantages. The article discusses using exosomes for various therapeutic agents, including drugs, antigens, and RNAs. It also examines challenges with engineered exosomes. Analyzing exosomes for clinical purposes faces limitations in sensitivity, specificity, and purification. On the other hand, Nanotechnology offers solutions to overcome these challenges and unlock exosome potential in healthcare. Overall, the article emphasizes the potential of exosomes for personalized and targeted cancer therapy, while acknowledging the need for further research.

Smart Nanoscale Extracellular Vesicles in the Brain: Unveiling their Biology, Diagnostic Potential, and Therapeutic Applications

Information exchange is essential for the brain, where it communicates the physiological and pathological signals to the periphery and vice versa. Extracellular vesicles (EVs) are a heterogeneous group of membrane-bound cellular informants actively transferring informative calls to and from the brain via lipids, proteins, and nucleic acid cargos. In recent years, EVs have also been widely used to understand brain function, given their "cell-like" properties. On the one hand, the presence of neuron and astrocyte-derived EVs in biological fluids have been exploited as biomarkers to understand the mechanisms and progression of multiple neurological disorders; on the other, EVs have been used in designing targeted therapies due to their potential to cross the blood-brain-barrier (BBB). Despite the expanding literature on EVs in the context of central nervous system (CNS) physiology and related disorders, a comprehensive compilation of the existing knowledge still needs to be made available. In the current review, we provide a detailed insight into the multifaceted role of brain-derived extracellular vesicles (BDEVs) in the intricate regulation of brain physiology. Our focus extends to the significance of these EVs in a spectrum of disorders, including brain tumors, neurodegenerative conditions, neuropsychiatric diseases, autoimmune disorders, and others. Throughout the review, parallels are drawn for using EVs as biomarkers for various disorders, evaluating their utility in early detection and monitoring. Additionally, we discuss the promising prospects of utilizing EVs in targeted therapy while acknowledging the existing limitations and challenges associated with their applications in clinical scenarios. A foundational comprehension of the current state-of-the-art in EV research is essential for informing the design of future studies.

Extracellular Vesicles in Transplantation: Friend or Foe

The long-term function of transplanted organs, even under immunosuppression, is hindered by rejection, especially chronic rejection. Chronic rejection occurs more frequently after lung transplantation, termed chronic lung allograft dysfunction (CLAD), than after transplantation of other solid organs. Pulmonary infection is a known risk factor for CLAD, as transplanted lungs are constantly exposed to the external environment; however, the mechanisms by which respiratory infections lead to CLAD are poorly understood. The role of extracellular vesicles (EVs) in transplantation remains largely unknown. Current evidence suggests that EVs released from transplanted organs can serve as friend and foe. EVs carry not only major histocompatibility complex antigens but also tissue-restricted self-antigens and various transcription factors, costimulatory molecules, and microRNAs capable of regulating alloimmune responses. EVs play an important role in antigen presentation by direct, indirect, and semidirect pathways in which CD8 and CD4 cells can be activated. During viral infections, exosomes (small EVs <200 nm in diameter) can express viral antigens and regulate immune responses. Circulating exosomes may also be a viable biomarker for other diseases and rejection after organ transplantation. Bioengineering the surface of exosomes has been proposed as a tool for targeted delivery of drugs and personalized medicine. This review focuses on recent studies demonstrating the role of EVs with a focus on exosomes and their dual role (immune activation or tolerance induction) after organ transplantation, more specifically, lung transplantation.

Nanoparticle Deep-Subwavelength Dynamics Empowered by Optical Meron-Antimeron Topology

Optical meron is a type of nonplanar topological texture mainly observed in surface plasmon polaritons and highly symmetric points of photonic crystals in the reciprocal space. Here, we report Poynting-vector merons formed at the real space of a photonic crystal for a Γ-point illumination. Optical merons can be utilized for subwavelength-resolution manipulation of nanoparticles, resembling a topological Hall effect on electrons via magnetic merons. In particular, staggered merons and antimerons impose strong radiation pressure on large gold nanoparticles (AuNPs), while focused hot spots in antimerons generate dominant optical gradient forces on small AuNPs. Synergistically, differently sized AuNPs in a still environment can be trapped or orbit in opposite directions, mimicking a coupled galaxy system. They can also be separated with a 10 nm precision when applying a flow velocity of >1 mm/s. Our study unravels a novel way to exploit topological textures for optical manipulation with deep-subwavelength precision and switchable topology in a lossless environment.

Recent Progress in Prompt Molecular Detection of Exosomes Using CRISPR/Cas and Microfluidic-Assisted Approaches Toward Smart Cancer Diagnosis and Analysis

Exosomes are essential indicators of molecular mechanisms involved in interacting with cancer cells and the tumor environment. As nanostructures based on lipids and nucleic acids, exosomes provide a communication pathway for information transfer by transporting biomolecules from the target cell to other cells. Importantly, these extracellular vesicles are released into the bloodstream by the most invasive cells, i. e., cancer cells; in this way, they could be considered a promising specific biomarker for cancer diagnosis. In this matter, CRISPR-Cas systems and microfluidic approaches could be considered practical tools for cancer diagnosis and understanding cancer biology. CRISPR-Cas systems, as a genome editing approach, provide a way to inactivate or even remove a target gene from the cell without affecting intracellular mechanisms. These practical systems provide vital information about the factors involved in cancer development that could lead to more effective cancer treatment. Meanwhile, microfluidic approaches can also significantly benefit cancer research due to their proper sensitivity, high throughput, low material consumption, low cost, and advanced spatial and temporal control. Thereby, employing CRISPR-Cas- and microfluidics-based approaches toward exosome monitoring could be considered a valuable source of information for cancer therapy and diagnosis. This review assesses the recent progress in these promising diagnosis approaches toward accurate cancer therapy and in-depth study of cancer cell behavior.

Engineering of Cell Derived-Nanovesicle as an Alternative to Exosome Therapy

BACKGROUND

Exosomes, nano-sized vesicles ranging between 30 and 150 nm secreted by human cells, play a pivotal role in long-range intercellular communication and have attracted significant attention in the field of regenerative medicine. Nevertheless, their limited productivity and cost-effectiveness pose challenges for clinical applications. These issues have recently been addressed by cell-derived nanovesicles (CDNs), which are physically synthesized exosome-mimetic nanovesicles from parent cells, as a promising alternative to exosomes. CDNs exhibit structural, physical, and biological properties similar to exosomes, containing intracellular protein and genetic components encapsulated by the cell plasma membrane. These characteristics allow CDNs to be used as regenerative medicine and therapeutics on their own, or as a drug delivery system.

METHODS

The paper reviews diverse methods for CDN synthesis, current analysis techniques, and presents engineering strategies to improve lesion targeting efficiency and/or therapeutic efficacy.

RESULTS

CDNs, with their properties similar to those of exosomes, offer a cost-effective and highly productive alternative due to their non-living biomaterial nature, nano-size, and readiness for use, allowing them to overcome several limitations of conventional cell therapy methods.

CONCLUSION

Ongoing research and enhancement of CDNs engineering, along with comprehensive safety assessments and stability analysis, exhibit vast potential to advance regenerative medicine by enabling the development of efficient therapeutic interventions.

Recent Progress in the Application of Exosome Analysis in Ovarian Cancer Management

Exosomes are very small (nano-sized) vesicles participating in tumor development by involvement in intercellular communication mediated by transferring biocomponents. Exosomes appear to play vital roles in various cancer development, such as ovarian cancer, a common malignancy in women. Several hallmarks of ovarian cancer are reported to be affected by the exosomemediated cellular cross-talk, including modulating peritoneal dissemination and chemoresistance. Since the expression of some biomolecules, such as miRNAs and mRNA, is changed in ovarian cancer, these exo-biomolecules can be applied as prognostic, diagnostic, and therapeutic biomarkers. Also, the selective loading of specific chemotherapeutic agents into exosomes highlights these biocarries as potential delivery devices. Exosomes could be artificially provided and engineered to better target the site of interest in ovarian cancer. In the present review, we summarize the notable achievement of exosome application in ovarian cancer management to gain applicable transitional insight against this cancer.

Exosomes: Methods for Isolation and Characterization in Biological Samples

Exosomes are small lipid bilayer-encapsulated nanosized extracellular vesicles of endosomal origin. Exosomes are secreted by almost all cell types and are a crucial player in intercellular communication. Exosomes transmit cellular information from donor to recipient cells in the form of proteins, lipids, and nucleic acids and influence several physiological and pathological responses. Due to their capacity to carry a variety of cellular cargo, low immunogenicity and cytotoxicity, biocompatibility, and ability to cross the blood-brain barrier, these nanosized vesicles are considered excellent diagnostic tools and drug-delivery vehicles. Despite their tremendous potential, the progress in therapeutic applications of exosomes is hindered by inadequate isolation techniques, poor characterization, and scarcity of specific biomarkers. The current research in the field is focused on overcoming these limitations. In this chapter, we have reviewed conventional exosome isolation and characterization methods and recent advancements, their advantages and limitations, persistent challenges in exosome research, and future directions.

A review on the use of extracellular vesicles for the delivery of drugs and biological therapeutics

INTRODUCTION

Exosomes, a type of extracellular vesicles, are effective tools for delivering small-molecule drugs and biological therapeutics into cells and tissues. Surface modifications with targeting ligands ensure precise delivery to specific cells, minimizing accumulation in healthy organs and reducing the side effects. This is a rapidly growing area in drug delivery research and this review aims to comprehensively discuss the recent advances in the field.

AREA COVERED

Recent studies have presented compelling evidence supporting the application of exosomes as efficient delivery vehicles that escape endosome trapping, achieving effective in vivo delivery in animal models. This review provides a systemic discussion on the exosome-based delivery technology, with topics covering exosome purification, surface modification, and targeted delivery of various cargos ranging from siRNAs, miRNAs, and proteins, to small molecule drugs.

EXPERT OPINION

Exosome-based gene and drug delivery has low toxicity and low immunogenicity. Surface modifications of the exosomes can effectively avoid endosome trapping and increase delivery efficiency. This exciting technology can be applied to improve the treatments for a wide variety of diseases.

Translational Challenges and Prospective Solutions in the Implementation of Biomimetic Delivery Systems

Biomimetic delivery systems (BDSs), inspired by the intricate designs of biological systems, have emerged as a groundbreaking paradigm in nanomedicine, offering unparalleled advantages in therapeutic delivery. These systems, encompassing platforms such as liposomes, protein-based nanoparticles, extracellular vesicles, and polysaccharides, are lauded for their targeted delivery, minimized side effects, and enhanced therapeutic outcomes. However, the translation of BDSs from research settings to clinical applications is fraught with challenges, including reproducibility concerns, physiological stability, and rigorous efficacy and safety evaluations. Furthermore, the innovative nature of BDSs demands the reevaluation and evolution of existing regulatory and ethical frameworks. This review provides an overview of BDSs and delves into the multifaceted translational challenges and present emerging solutions, underscored by real-world case studies. Emphasizing the potential of BDSs to redefine healthcare, we advocate for sustained interdisciplinary collaboration and research. As our understanding of biological systems deepens, the future of BDSs in clinical translation appears promising, with a focus on personalized medicine and refined patient-specific delivery systems.

Ultrafast and Controlled Capturing, Loading, and Release of Extracellular Vesicles by a Portable Microstructured Electrochemical Fluidic Device

Extracellular vesicles (EVs) are secreted by all living cells and are found in body fluids. They exert numerous physiological and pathological functions and serve as cargo shuttles. Due to their safety and inherent bioactivity, they have emerged as versatile therapeutic agents, biomarkers, and potential drug carriers. Despite the growing interest in EVs, current progress in this field is, in part, limited by relatively inefficient isolation techniques. Conventional methods are indeed slow, laborious, require specialized laboratory equipment, and may result in low yield and purity. This work describes an electrochemically controlled "all-in-one" device enabling capturing, loading, and releasing of EVs. The device is composed of a fluidic channel confined within antibody-coated microstructured electrodes. It rapidly isolates EVs with a high level of purity from various biofluids. As a proof of principle, the device is applied to isolate EVs from skin wounds of healthy and diabetic mice. Strikingly, it is found that EVs from healing wounds of diabetic mice are enriched in mitochondrial proteins compared to those of healthy mice. Additionally, the device improves the loading protocol of EVs with polyplexes, and may therefore find applications in nucleic acid delivery. Overall, the electrochemical device can greatly facilitate the development of EVs-based technologies.

Rapid purification and multiparametric characterization of circulating small extracellular vesicles utilizing a label-free lab-on-a-chip device

Nano-scale extracellular vesicles are lipid-bilayer delimited particles that are naturally secreted by all cells and have emerged as valuable biomarkers for a wide range of diseases. Efficient isolation of small extracellular vesicles while maintaining yield and purity is crucial to harvest their potential in diagnostic, prognostic, and therapeutic applications. Most conventional methods of isolation suffer from significant shortcomings, including low purity or yield, long duration, need for large sample volumes, specialized equipment, trained personnel, and high costs. To address some of these challenges, our group has reported a novel insulator-based dielectrophoretic device for rapid isolation of small extracellular vesicles from biofluids and cell culture media based on their size and dielectric properties. In this study, we report a comprehensive characterization of small extracellular vesicles isolated from cancer-patients' biofluids at a twofold enrichment using the device. The three-fold characterization that was performed using conventional flow cytometry, advanced imaging flow cytometry, and microRNA sequencing indicated high yield and purity of the isolated small extracellular vesicles. The device thus offers an efficient platform for rapid isolation while maintaining biomolecular integrity.

Direct isolation of small extracellular vesicles from human blood using viscoelastic microfluidics

Small extracellular vesicles (sEVs; <200 nm) that contain lipids, nucleic acids, and proteins are considered promising biomarkers for a wide variety of diseases. Conventional methods for sEV isolation from blood are incompatible with routine clinical workflows, significantly hampering the utilization of blood-derived sEVs in clinical settings. Here, we present a simple, viscoelastic-based microfluidic platform for label-free isolation of sEVs from human blood. The separation performance of the device is assessed by isolating fluorescent sEVs from whole blood, demonstrating purities and recovery rates of over 97 and 87%, respectively. Significantly, our viscoelastic-based microfluidic method also provides for a remarkable increase in sEV yield compared to gold-standard ultracentrifugation, with proteomic profiles of blood-derived sEVs purified by both methods showing similar protein compositions. To demonstrate the clinical utility of the approach, we isolate sEVs from blood samples of 20 patients with cancer and 20 healthy donors, demonstrating that elevated sEV concentrations can be observed in blood derived from patients with cancer.

Filtration-based technologies for isolation, purification and analysis of extracellular vesicles

The involvement of extracellular vesicles (EVs) in cellular communication with multifactorial and multifaceted biological activity has generated significant interest, highlighting their potential diagnostic and therapeutic applications. EVs are found in nearly all biological fluids creating a broad spectrum of where potential disease markers can be found for liquid biopsy development and what subtypes can be used for treatment of diseases. Complexity of biological fluids has generated a variety of different approaches for EV isolation and identification that may in one way or another be most optimal for research studies or clinical use. Each approach has its own advantages and disadvantages, significance of which can be evaluated depending on the end goal of the study. One of the methods is based on filtration which has received attention in the past years due its versatility, low cost and other advantages. Introduction of different approaches for EV capture and analysis that are based on filtration gave rise to new subcategories of filtration techniques which are presented in this overview. Miniaturization and combination of filtration-based approaches with microfluidics is also highlighted due its future prospects in healthcare, especially point-of-need technologies.

Extracellular Vesicles as Source of Biomarkers in Glomerulonephritis

Kidney disease is a global health and healthcare burden. Glomerulonephritis (Gn), both primary and secondary, is generally characterized by an inflammatory glomerular injury and may lead to end-stage renal disease. Kidney biopsy is fundamental to the diagnosis; however, kidney biopsy presents some concerns that may partly hamper the clinical process. Therefore, more accurate diagnostic tools are needed. Extracellular vesicles (EVs) are membranous vesicles released by cells and found in bodily fluids, including urine. EVs mediate intercellular signaling both in health and disease. EVs can have both harmful and cytoprotective effects in kidney diseases, especially Gn. Previous findings reported that the specific cargo of urinary EV contains an aerobic metabolic ability that may either restore the recipient cell metabolism or cause oxidative stress production. Here, we provide an overview of the most recent proteomic findings on the role of EVs in several aspects of glomerulopathies, with a focus on this metabolic and redox potential. Future studies may elucidate how the ability of EVs to interfere with aerobic metabolism and redox status can shed light on aspects of Gn etiology which have remained elusive so far.

Extracellular vesicles: effectors of transfusion-related acute lung injury

Respiratory transfusion reactions represent some of the most severe adverse reactions related to receiving blood products. Of those, transfusion-related acute lung injury (TRALI) is associated with elevated morbidity and mortality. TRALI is characterized by severe lung injury associated with inflammation, pulmonary neutrophil infiltration, lung barrier leak, and increased interstitial and airspace edema that cause respiratory failure. Presently, there are few means of detecting TRALI beyond clinical definitions based on physical examination and vital signs or preventing/treating TRALI beyond supportive care with oxygen and positive pressure ventilation. Mechanistically, TRALI is thought to be mediated by the culmination of two successive proinflammatory hits, which typically comprise a recipient factor (1st hit-e.g., systemic inflammatory conditions) and a donor factor (2nd hit-e.g., blood products containing pathogenic antibodies or bioactive lipids). An emerging concept in TRALI research is the contribution of extracellular vesicles (EVs) in mediating the first and/or second hit in TRALI. EVs are small, subcellular, membrane-bound vesicles that circulate in donor and recipient blood. Injurious EVs may be released by immune or vascular cells during inflammation, by infectious bacteria, or in blood products during storage, and can target the lung upon systemic dissemination. This review assesses emerging concepts such as how EVs: 1) mediate TRALI, 2) represent targets for therapeutic intervention to prevent or treat TRALI, and 3) serve as biochemical biomarkers facilitating TRALI diagnosis and detection in at-risk patients.

Harnessing the therapeutic potential of mesenchymal stem cell-derived exosomes in cardiac arrest: Current advances and future perspectives

BACKGROUND

Cardiac arrest (CA), characterized by sudden onset and high mortality rates, is one of the leading causes of death globally, with a survival rate of approximately 6-24%. Studies suggest that the restoration of spontaneous circulation (ROSC) hardly improved the mortality rate and prognosis of patients diagnosed with CA, largely due to ischemia-reperfusion injury.

MAIN BODY

Mesenchymal stem cells (MSCs) exhibit self-renewal and strong potential for multilineage differentiation. Their effects are largely mediated by extracellular vesicles (EVs). Exosomes are the most extensively studied subgroup of EVs. EVs mainly mediate intercellular communication by transferring vesicular proteins, lipids, nucleic acids, and other substances to regulate multiple processes, such as cytokine production, cell proliferation, apoptosis, and metabolism. Thus, exosomes exhibit significant potential for therapeutic application in wound repair, tissue reconstruction, inflammatory reaction, and ischemic diseases.

CONCLUSION

Based on similar pathological mechanisms underlying post-cardiac arrest syndrome involving various tissues and organs in many diseases, the review summarizes the therapeutic effects of MSC-derived exosomes and explores the prospects for their application in the treatment of CA.

A tale of exosomes and their implication in cancer

Cancer is a cause of high deaths worldwide and also a huge burden for the health system. Cancer cells have unique properties such as a high rate of proliferation, self-renewal, metastasis, and treatment resistance, therefore, the development of novel diagnoses of cancers is a tedious task. Exosomes are secreted by virtually all cell types and have the ability to carry a multitude of biomolecules crucial for intercellular communication, hence, contributing a crucial part in the onset and spread of cancer. These exosomal components can be utilized in the development of markers for diagnostic and prognostic purposes for various cancers. This review emphasized primarily the following topics: exosomes structure and functions, isolation and characterization strategies of exosomes, the role of exosomal contents in cancer with a focus in particular on noncoding RNA and protein, exosomes, and the cancer microenvironment interactions, cancer stem cells, and tumor diagnosis and prognosis based on exosomes.

The Role of Small Extracellular Vesicles Derived from Mesenchymal Stromal Cells on Myocardial Protection: a Review of Current Advances and Future Perspectives

Small extracellular vesicles (SEVs) secreted by mesenchymal stromal cells (MSCs) are considered one of the most promising biological therapies in recent years. The protective effect of MSCs-derived SEVs on myocardium is mainly related to their ability to deliver cargo, anti-inflammatory properties, promotion of angiogenesis, immunoregulation, and other factors. Herein, this review focuses on the biological properties, isolation methods, and functions of SEVs. Then, the roles and potential mechanisms of SEVs and engineered SEVs in myocardial protection are summarized. Finally, the current situation of clinical research on SEVs, the difficulties encountered, and the future fore-ground of SEVs are discussed. In conclusion, although there are some technical difficulties and conceptual contradictions in the research of SEVs, the unique biological functions of SEVs provide a new direction for the development of regenerative medicine. Further exploration is warranted to establish a solid experimental and theoretical basis for future clinical application of SEVs.

Continuous-flow label-free size fractionation of extracellular vesicles through electrothermal fluid rolls and dielectrophoresis synergistically integrated in a microfluidic device

Extracellular vesicles (EVs) are cell-derived bioparticles that play significant roles in various biological processes including cell-to-cell communication and intercellular delivery. Additionally, they hold great potential as liquid biopsy biomarkers for pre-diagnostic applications. However, the isolation of EV subpopulations, especially exosomes from a biological fluid remains a challenge due to their submicron range. Here, we demonstrate continuous-flow label-free size fractionation of EVs for the first time through a synergistic combination of electrothermal fluid rolls and dielectrophoresis in a microfluidic device. The device features three dimensional microelectrodes with unique sidewall contours that give rise to effective electrothermal fluid rolls in cooperation with dielectrophoretic forces for the electrokinetic manipulation and size separation of submicron particles. We first validate the device functionality by separating submicron polystyrene particles from binary mixtures with a cut-off size of ∼200 nm and then isolate intact exosomes from cell culture medium or blood serum with a high recovery rate and purity (∼80%). The device operation in a high-conductivity medium renders the method ideal for the purification of target bioparticles directly from physiological fluids, and may offer a robust and versatile platform for EV related diagnostic applications.

Isolation of Bovine Milk Exosome Using Electrophoretic Oscillation Assisted Tangential Flow Filtration with Antifouling of Micro-ultrafiltration Membrane Filters

Tangent flow-driven ultrafiltration (TF-UF) is an efficient isolation process of milk exosomes without morphological deformation. However, the TF-UF approach with micro-ultrafiltration SiN_x membrane filters suffers from the clogging and fouling of micro-ultrafiltration membrane filter pores with large bioparticles. Thus, it is limited in the long term, continuous isolation of large quantities of exosomes. In this work, we introduced electrophoretic oscillation (EPO) in the TF-UF approach to remove pore clogging and fouling of with micro-ultrafiltration SiN_x membrane filters by large bioparticles. As a result, the combined EPO-assisted TF (EPOTF) filtration can isolate large quantities of bovine milk exosomes without deformation. Furthermore, several morphological and biological analyses confirmed that the EPOTF filtration approach could isolate the milk exosomes in high concentrations with high purity and intact morphology. In addition, the uptake test of fluorescent-labeled exosomes by the keratinocyte cells visualized the biological function of purified exosomes. Hence, compared to the TF-UF process, the EPOTF filtration produced a higher yield of bovine milk exosomes without stopping the filtering process for over 200 h. Therefore, this isolation process enables scalable and continuous production of morphologically intact exosomes from bovine milk, suggesting that high-quality exosome purification is possible for future applications such as drug nanocarriers, diagnosis, and treatments.

Clinical Application of Small Extracellular Vesicles in Gynecologic Malignancy Treatments

Small extracellular vesicles (sEVs) are the key mediators of intercellular communication. They have the potential for clinical use as diagnostic or therapeutic biomarkers and have been explored as vectors for drug delivery. Identification of reliable and noninvasive biomarkers, such as sEVs, is important for early diagnosis and precise treatment of gynecologic diseases to improve patient prognosis. Previous reviews have summarized routine sEVs isolation and identification methods; however, novel and unconventional methods have not been comprehensively described. This review summarizes a convenient method of isolating sEVs from body fluids and liquid biopsy-related sEV markers for early, minimally invasive diagnosis of gynecologic diseases. In addition, the characteristics of sEVs as drug carriers and in precision treatment and drug resistance are introduced, providing a strong foundation for identifying novel and potential therapeutic targets for sEV therapy. We propose potential directions for further research on the applications of sEVs in the diagnosis and treatment of gynecologic diseases.

Engineered exosomes from different sources for cancer-targeted therapy

Exosome is a subgroup of extracellular vesicles, which has been serving as an efficient therapeutic tool for various diseases. Engineered exosomes are the sort of exosomes modified with surface decoration and internal therapeutic molecules. After appropriate modification, engineered exosomes are able to deliver antitumor drugs to tumor sites efficiently and precisely with fewer treatment-related adverse effects. However, there still exist many challenges for the clinical translation of engineered exosomes. For instance, what sources and modification strategies could endow exosomes with the most efficient antitumor activity is still poorly understood. Additionally, how to choose appropriately engineered exosomes in different antitumor therapies is another unresolved problem. In this review, we summarized the characteristics of engineered exosomes, especially the spatial and temporal properties. Additionally, we concluded the recent advances in engineered exosomes in the cancer fields, including the sources, isolation technologies, modification strategies, and labeling and imaging methods of engineered exosomes. Furthermore, the applications of engineered exosomes in different antitumor therapies were summarized, such as photodynamic therapy, gene therapy, and immunotherapy. Consequently, the above provides the cancer researchers in this community with the latest ideas on engineered exosome modification and new direction of new drug development, which is prospective to accelerate the clinical translation of engineered exosomes for cancer-targeted therapy.

Liquid Biopsies, Novel Approaches and Future Directions

Cancer is among the leading causes of death worldwide. Early diagnosis and prognosis are vital to improve patients' outcomes. The gold standard of tumor characterization leading to tumor diagnosis and prognosis is tissue biopsy. Amongst the constraints of tissue biopsy collection is the sampling frequency and the incomplete representation of the entire tumor bulk. Liquid biopsy approaches, including the analysis of circulating tumor cells (CTCs), circulating tumor DNA (ctDNA), circulating miRNAs, and tumor-derived extracellular vesicles (EVs), as well as certain protein signatures that are released in the circulation from primary tumors and their metastatic sites, present a promising and more potent candidate for patient diagnosis and follow up monitoring. The minimally invasive nature of liquid biopsies, allowing frequent collection, can be used in the monitoring of therapy response in real time, allowing the development of novel approaches in the therapeutic management of cancer patients. In this review we will describe recent advances in the field of liquid biopsy markers focusing on their advantages and disadvantages.

Recent microfluidic advances in submicron to nanoparticle manipulation and separation

Manipulation and separation of submicron and nanoparticles are indispensable in many chemical, biological, medical, and environmental applications. Conventional technologies such as ultracentrifugation, ultrafiltration, size exclusion chromatography, precipitation and immunoaffinity capture are limited by high cost, low resolution, low purity or the risk of damage to biological particles. Microfluidics can accurately control fluid flow in channels with dimensions of tens of micrometres. Rapid microfluidics advancement has enabled precise sorting and isolating of nanoparticles with better resolution and efficiency than conventional technologies. This paper comprehensively studies the latest progress in microfluidic technology for submicron and nanoparticle manipulation. We first summarise the principles of the traditional techniques for manipulating nanoparticles. Following the classification of microfluidic techniques as active, passive, and hybrid approaches, we elaborate on the physics, device design, working mechanism and applications of each technique. We also compare the merits and demerits of different microfluidic techniques and benchmark them with conventional technologies. Concurrently, we summarise seven standard post-separation detection techniques for nanoparticles. Finally, we discuss current challenges and future perspectives on microfluidic technology for nanoparticle manipulation and separation.

Alternative biological sources for extracellular vesicles production and purification strategies for process scale-up

Extracellular vesicles (EVs) are phospholipidic bi-layer enclosed nanoparticles secreted naturally by all cell types. They are attracting increasing attention in the fields of nanomedicine, nutraceutics and cosmetics as biocompatible carriers for drug delivery, with intrinsic properties beneficial to human health. Scientific work now focuses on developing techniques for isolating EVs that can translate into industrial-scale production and meet rigorous clinical requirements. The science of EVs is ongoing, and many pitfalls must be addressed, such as the requirement for standard, reproducible, inexpensive, and Good Manufacturing Practices (GMP) adherent EV processing techniques. Researchers are exploring the use of alternative sources to EVs derived from mammalian cultures, such as plant EVs, as well as the use of bacteria, algae and milk. Regarding the downstream processing of EVs, many alternative techniques to the ultracentrifugation (UC) protocols most commonly used in the laboratory are emerging. In the context of process scale-up, membrane-based processes for isolation and purification of EVs are the most promising, either as stand-alone processes or in combination with chromatographic techniques. This review discusses current trends on EVs source selection and EVs downstream processing techniques, with a focus on plant-derived EVs and membrane-based techniques for EVs enrichment.

A review on comparative studies addressing exosome isolation methods from body fluids

Exosomes emerged as valuable sources of disease biomarkers and new therapeutic tools. However, extracellular vesicles isolation with exosome-like characteristics from certain biofluids is still challenging which can limit their potential use in clinical settings. While ultracentrifugation-based procedures are the gold standard for exosome isolation from cell cultures, no unique and standardized method for exosome isolation from distinct body fluids exists. The complexity, specific composition, and physical properties of each biofluid constitute a technical barrier to obtain reproducible and pure exosome preparations, demanding a detailed characterization of both exosome isolation and characterization methods. Moreover, some isolation procedures can affect downstream proteomic or RNA profiling analysis. This review compiles and discussed a set of comparative studies addressing distinct exosome isolation methods from human biofluids, including cerebrospinal fluid, plasma, serum, saliva, and urine, also focusing on body fluid specific challenges, physical properties, and other potential variation sources. This summarized information will facilitate the choice of exosome isolation methods, based on the type of biological samples available, and hopefully encourage the use of exosomes in translational and clinical research.

Potential of Mesenchymal Stromal Cell-Derived Extracellular Vesicles as Natural Nanocarriers: Concise Review

Intercellular communication, through direct and indirect cell contact, is mandatory in multicellular organisms. These last years, the microenvironment, and in particular, transfer by extracellular vesicles (EVs), has emerged as a new communication mechanism. Different biological fluids and cell types are common sources of EVs. EVs play different roles, acting as signalosomes, biomarkers, and therapeutic agents. As therapeutic agents, MSC-derived EVs display numerous advantages: they are biocompatible, non-immunogenic, and stable in circulation, and they are able to cross biological barriers. Furthermore, EVs have a great potential for drug delivery. Different EV isolation protocols and loading methods have been tested and compared. Published and ongoing clinical trials, and numerous preclinical studies indicate that EVs are safe and well tolerated. Moreover, the latest studies suggest their applications as nanocarriers. The current review will describe the potential for MSC-derived EVs as drug delivery systems (DDS) in disease treatment, and their advantages. Thereafter, we will outline the different EV isolation methods and loading techniques, and analyze relevant preclinical studies. Finally, we will describe ongoing and published clinical studies. These elements will outline the benefits of MSC-derived EV DDS over several aspects.

Isolation of Extracellular Vesicles from Human Follicular Fluid: Size-Exclusion Chromatography versus Ultracentrifugation

Follicular fluid (FF) is the microenvironment where a growing oocyte develops. Intrafollicular communication ensures oocyte competence and is carried out through paracrine signaling, the exchange of molecules via gap junctions, and the trafficking of extracellular vesicles (EVs). The study of FF-derived EVs is important for both translational and fundamental research in the female reproductive field. This study aimed to compare the efficacy and purity of two EV isolation methods: size-exclusion chromatography (SEC) and ultracentrifugation (UC). EVs isolated using SEC and UC were compared regarding their size and concentration using dynamic light scattering (DLS) and nanoparticle tracking analysis (NTA); protein contamination was assessed with microBCA; specific EV markers were detected with Western blot, and EV morphology was studied with transmission electron microscopy (TEM). Our results show that although both techniques isolated small EVs, a significantly increased yield in particle number was clear with UC compared with SEC. On the other hand, SEC generated purer EVs with fewer protein contaminants and aggregates. In conclusion, the selection of the most suited approach to isolate EVs must be conducted considering the degree of recovery, purity, and downstream application of the isolated EVs.

A compendium of single extracellular vesicle flow cytometry

Flow cytometry (FCM) offers a multiparametric technology capable of characterizing single extracellular vesicles (EVs). However, most flow cytometers are designed to detect cells, which are larger than EVs. Whereas cells exceed the background noise, signals originating from EVs partly overlap with the background noise, thereby making EVs more difficult to detect than cells. This technical mismatch together with complexity of EV-containing fluids causes limitations and challenges with conducting, interpreting and reproducing EV FCM experiments. To address and overcome these challenges, researchers from the International Society for Extracellular Vesicles (ISEV), International Society for Advancement of Cytometry (ISAC), and the International Society on Thrombosis and Haemostasis (ISTH) joined forces and initiated the EV FCM working group. To improve the interpretation, reporting, and reproducibility of future EV FCM data, the EV FCM working group published an ISEV position manuscript outlining a framework of minimum information that should be reported about an FCM experiment on single EVs (MIFlowCyt-EV). However, the framework contains limited background information. Therefore, the goal of this compendium is to provide the background information necessary to design and conduct reproducible EV FCM experiments. This compendium contains background information on EVs, the interaction between light and EVs, FCM hardware, experimental design and preanalytical procedures, sample preparation, assay controls, instrument data acquisition and calibration, EV characterization, and data reporting. Although this compendium focuses on EVs, many concepts and explanations could also be applied to FCM detection of other particles within the EV size range, such as bacteria, lipoprotein particles, milk fat globules, and viruses.

Exosomes and exosome-loaded scaffolds: Characterization and application in modern regenerative medicine

Exosomes (EXOs) are extracellular vesicles derived from the endosome. These heterogeneous nanoparticles (30-150 nm) are secreted from various cells and play important biological roles in intercellular communication. EXOs have received much attention for application in regenerative therapies and tissue repair due to their stability, biosafety, and functional versatility. However, in their free forms, "EXOs have poor bioavailability" at the site of action and are devoid of controlled-release mechanisms. These issues have been largely remedied by scaffolding EXOs with appropriate biomaterials such as hydrogels to create EXOs -loaded scaffold (ELS). These biomaterial-based scaffolds can be rationally designed and functionalized to enhance various aspects of ELS including bioavailability, biocompatibility, and loading/release control. Additionally, the ELS are superior to free EXOs due to reduced injection-related side effects. This review article provides a comprehensive and updated account of EXOs and ELS isolation, characterization, and application in regenerative medicine with a focus on soft tissue repair. We also offer insights into the advantages of ELS therapy compared to stem cell therapy towards application in wound healing, cardiac and bone repair. ELS promotes cell migration to the scaffold and will cause better homing of exosomes. Different types of scaffolds are made and each one can be modified based on the repair in the target tissues so that the reactions between the scaffold and exosome take place properly and effective signals are created for tissue repair.

Exosomes: the latest in regenerative aesthetics

Regenerative aesthetics is a burgeoning field for skin rejuvenation and skin health restoration. Exosomes, or extracellular vesicles, represent a new and minimally invasive addition to the regenerative aesthetic toolbox. These nano-sized vesicles contain bioactive cargo with crucial roles in intercellular communication. Exosome technology, while still in its infancy, is now leveraged in regenerative aesthetic medicine due to its multifaceted role in targeting root causes of skin aging and improving overall tissue homeostasis. The main considerations for practice utilization include variation in exosome purification, isolation, storage, scalability and reproducibility. This review aims at highlighting the current and emerging landscape of exosomes in aesthetic medicine including skin rejuvenation and hair restoration.

Microfluidics facilitating the use of small extracellular vesicles in innovative approaches to male infertility

Sperm are transcriptionally and translationally quiescent and, therefore, rely on the seminal plasma microenvironment for function, survival and fertilization of the oocyte in the oviduct. The male reproductive system influences sperm function via the binding and fusion of secreted epididymal (epididymosomes) and prostatic (prostasomes) small extracellular vesicles (S-EVs) that facilitate the transfer of proteins, lipids and nucleic acids to sperm. Seminal plasma S-EVs have important roles in sperm maturation, immune and oxidative stress protection, capacitation, fertilization and endometrial implantation and receptivity. Supplementing asthenozoospermic samples with normospermic-derived S-EVs can improve sperm motility and S-EV microRNAs can be used to predict non-obstructive azoospermia. Thus, S-EV influence on sperm physiology might have both therapeutic and diagnostic potential; however, the isolation of pure populations of S-EVs from bodily fluids with current conventional methods presents a substantial hurdle. Many conventional techniques lack accuracy, effectiveness, and practicality; yet microfluidic technology has the potential to simplify and improve S-EV isolation and detection.

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 Rise of Extracellular Vesicles as New Age Biomarkers in Cancer Diagnosis: Promises and Pitfalls

Cell-to-cell interactions in the intricate microenvironment of tissue have a significant impact on the progression of cancer at every stage. Both cancer cells and stromal cells are responsible for the secretion of soluble chemical compounds as well as membrane-encased components, which both influence and govern the cell-to-cell interactions within the micro-environment of tumor cells. These membrane structures are identified as extracellular vesicles (EVs), which include exosomes and microvesicles. These nanosized vesicles are made up of bilayered proteolipids and have dimensions ranging from 50 to 1000 nm. It has been speculated that extracellular vesicles that originate from cancer cells perform a variety of functions in the development and progression of cancer which may involve the transport of regulatory materials, such as oncogenic proteins between nearby cells and to distant biological locations. In addition, their level in the serum of cancer patients is noticeably higher than those of healthy controls. The release of extracellular vesicles into the extracellular space is a continual process in both healthy and diseased cells. These extracellular vesicles hold molecular signatures that are defining features of health as well as disease. And hence, the EVs present in biological fluids provide unparalleled and noninvasive access to the necessary molecular details about the health status of the cells. Recent discoveries about these complex extracellular organelles have accelerated the discovery of cancer-specific biological markers as well as the development of unique diagnostic tools based on extracellular vesicles. In this mini-review, we aim to highlight the hopes and hypes associated with the applications of extracellular vesicles as biomarkers for cancer diagnosis.

Isolation and characterization of extracellular vesicles and future directions in diagnosis and therapy

Extracellular vesicles (EVs) are a unique and heterogeneous class of lipid bilayer nanoparticles secreted by most cells. EVs are regarded as important mediators of intercellular communication in both prokaryotic and eukaryotic cells due to their ability to transfer proteins, lipids and nucleic acids to recipient cells. In addition to their physiological role, EVs are recognized as modulators in pathological processes such as cancer, infectious diseases, and neurodegenerative disorders, providing new potential targets for diagnosis and therapeutic intervention. For a complete understanding of EVs as a universal cellular biological system and its translational applications, optimal techniques for their isolation and characterization are required. Here, we review recent progress in those techniques, from isolation methods to characterization techniques. With interest in therapeutic applications of EVs growing, we address fundamental points of EV-related cell biology, such as cellular uptake mechanisms and their biodistribution in tissues as well as challenges to their application as drug carriers or biomarkers for less invasive diagnosis or as immunogens. This article is categorized under: Diagnostic Tools > Biosensing Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease.