Isolation of High-Purity Extracellular Vesicles by Extracting Proteins Using Aqueous Two-Phase System

Exosome isolation based on polyethylene glycol (PEG): a review

Exosome acts as an outstanding biomarker for ongoing studies, diagnosis and prognosis of multiples diseases. Therefore, the call for economically and efficiently isolating a large number of exosomes is an active area of investigation. However, to date, the challenges including complex isolated procedure, uneconomical equipment, low protein content and distinct loss in the particle number of exosomes etc. still encounter in exosome isolation. Polyethylene glycol (PEG)-induced exosome isolation increasingly attracts wide attention of scientists. PEG precipitation reveals higher performance in the yield of exosomes among multiple common isolation techniques. PEG-based precipitation is a temporarily low-purity, but inexpensive, time-save, labor-less, convenient and high-yield technique to gain exosomes with high biological activities. Hence, the PEG-based exosome isolation approach wins the endorsement of experimental workers. Herein, we summary the existing knowledge on procedures of PEG-based exosomes separation from different biospecimens, the binding process of PEG to exosomes, some notices, demerits, merits of PEG-based exosome isolation, and at last the advantages by combining PEG-precipitation to other techniques for exosome isolation, with a view to eliciting profound insights for investigators who recruit PEG for exosome separation, and advancing references for the standardization of PEG-based exosome isolation in future.

Diagnosis of Prostate Cancer Metastasis via Extracellular Vesicles Isolated Using Two-Phase Interface as Membrane-Less Filter

Extracellular vesicles (EVs), nano-sized particles secreted by cells, are increasingly recognized as promising biomarkers. However, the isolation and purification of EVs need improvement, impeding their practical application. Aqueous two-phase systems (ATPS) offer a method to separate EVs with high purity and yield compared to other techniques, yet the unclear isolation mechanism limits efficiency. To elucidate the separation process and enhance ATPS-based EV isolation, Kramers' theory and Fick's law are employed. The simulations and experiments reveal that the liquid-liquid interface in ATPS acts as a size cut-off filter for EVs, functioning without a membrane. It is discovered that rapid transport of particles to the interface is crucial for fast isolation, but this transport in separated phases relies solely on diffusion, which slows the process. To address this, a vortex is introduced to enhance particle movement through convection, significantly improving efficiency. This method achieves over 80% recovery of EVs from blood plasma and removes more than 90% of low-density lipoprotein, high-density lipoprotein, and albumin within an hour. Applying this ATPS-based membrane-less filter to plasma from prostate cancer patients, concentrations of markers on EVs are quantified. Using machine learning, metastatic and non-metastatic prostate cancer are distinguished with greater accuracy than the traditional PSA-based method.

The prospective roles of exosomes in pituitary tumors

Pituitary neuroendocrine tumors are common, typically benign intracranial neoplasms arising from well-differentiated anterior pituitary cells with prevalence of clinically relevant pituitary tumor of 89 in 100 000 people. Despite the growing number of published studies, there is still a need for diagnostic and predictive biomarkers of pituitary adenomas. Prompt determination of tendency of the tumor for invasive growth and aggressive behavior would allow for earlier and more effective treatment. Extracellular vesicles (EVs), including exosomes, are particles released by cells containing cell-specific cargo including a variety of bioactive molecules, such as DNA, messenger RNA, microRNA, long non-coding RNA, circular RNA, proteins, and lipids surrounded by lipid membranes, which act as mediators of cell to cell communication. The ability of exosomes to reflect the functional state of the tumor, transport informative molecules, and accessibility in body fluids make them promising candidates in the search for biomarkers and new therapeutic methods. This study aims to investigate the involvement of exosomes in the pathology of pituitary adenoma and their potential clinical applications.

Salivary Extracellular Vesicles Separation: Analysis of Ultracentrifugation-Based Protocols

INTRODUCTION

The clinical potential of extracellular vesicles (EVs) is widely acknowledged, yet the standardization and reproducibility of its separation remain challenging. This study compares three protocols: ultracentrifugation (UC), UC with purification step (UC + PS), and a combined protocol using polymer-based precipitation and UC (PBP + UC).

METHODS

Salivary samples were collected from healthy donors. EVs were separated (UC, UC + PS, and PBP + UC) and characterized using transmission electron microscopy, nanoparticle tracking analysis, EV purity, RNA concentration, and Western blotting. miRNA expression was evaluated by quantitative RT-PCR. Statistical analyses comparing groups were performed using ANOVA.

RESULTS

All methods successfully separated CD9+ and CD63+ EVs from saliva. The UC + PS and PBP + UC protocols yielded the highest concentrations of EVs, enriched in < 200 nm vesicles. EV purity and RNA recovery were comparable among all methods. Expression of miR-16, miR-27a, and miR-99a was successfully detected using all methods.

CONCLUSIONS

The UC + PS and PBP + UC protocols demonstrate comparable efficiency in separating salivary EVs. However, the combined PBP + UC protocol, with its simplified processing capability, offers a significant advantage, particularly in the initial phase of EV separation. This finding suggests its potential application in clinical settings where time-sensitive simple processing is critical. Further validation is needed to confirm its effectiveness for transcriptomic and proteomic analyses.

Repeated Injections of Mesenchymal Stem Cell-Derived Exosomes Ameliorate Erectile Dysfunction in a Cavernous Nerve Injury Rat Model

PURPOSE

To evaluate the therapeutic effect of repeated injections of mesenchymal stem cell (MSC)-derived exosomes on the erectile dysfunction (ED) of bilateral cavernous nerve injury (BCNI) rat model and to identify potential target genes of these injections.

MATERIALS AND METHODS

MSC-derived exosomes were isolated using an aqueous two-phase system. Rats were randomly assigned into four groups: Normal, BCNI, exosome once, and exosome-repeat groups. After four weeks, we measured the intracavernosal pressure (ICP)/mean arterial pressure (MAP) ratio to evaluate erectile function and examined cavernous nerve tissues for histological and molecular analyses. RNA sequencing in penile tissues was used to determine differentially expressed genes and was verified by quantitative polymerase chain reaction. Human umbilical vein endothelial cells (HUVECs) were used for in vitro studies to analyze biological roles.

RESULTS

The ICP/MAP ratios in the exosome-once and exosome-repeat groups were significantly increased compared to those in the BCNI group. Interestingly, the ICP/MAP ratio showed a greater increase in the exosome-repeat group, which also showed significantly increased smooth muscle/collagen ratio, α-smooth muscle actin and neuronal nitric oxide synthase expression, and cyclic guanosine monophosphate level compared to the BCNI and exosome-once groups. Three genes were significantly differentially expressed in the exosome group, among which Ras homolog family member B promoted cell proliferation and angiogenesis of HUVECs.

CONCLUSIONS

Repeated injections of MSC-derived exosomes can be effective in the treatment of rat models with ED induced by cavernous nerve injury.

Vascularized platforms for investigating cell communication via extracellular vesicles

The vascular network plays an essential role in the maintenance of all organs in the body via the regulated delivery of oxygen and nutrients, as well as tissue communication via the transfer of various biological signaling molecules. It also serves as a route for drug administration and affects pharmacokinetics. Due to this importance, engineers have sought to create physiologically relevant and reproducible vascular systems in tissue, considering cell-cell and extracellular matrix interaction with structural and physical conditions in the microenvironment. Extracellular vesicles (EVs) have recently emerged as important carriers for transferring proteins and genetic material between cells and organs, as well as for drug delivery. Vascularized platforms can be an ideal system for studying interactions between blood vessels and EVs, which are crucial for understanding EV-mediated substance transfer in various biological situations. This review summarizes recent advances in vascularized platforms, standard and microfluidic-based techniques for EV isolation and characterization, and studies of EVs in vascularized platforms. It provides insights into EV-related (patho)physiological regulations and facilitates the development of EV-based therapeutics.

Plant-derived extracellular vesicles: a synergetic combination of a drug delivery system and a source of natural bioactive compounds

Exosomes are extracellular nanovesicles secreted by all cell types and have been studied to understand and treat many human diseases. Exosomes are involved in numerous physiological and pathological processes, intercellular communication, and the transfer of substances. Over the years, several studies have explored mammalian-derived exosomes for therapeutic and diagnostic uses. Only recently have plant-derived extracellular vesicles (EVs) attracted attention for their ability to overcome many defects associated with using mammalian-derived extracellular vesicles, such as safety and scale-up issues. The ease of large-scale production, low toxicity, low immunogenicity, efficient cellular uptake, high biocompatibility, and high stability of these nanovesicles make them attractive for drug delivery systems. In addition, their native contents of proteins, miRNAs and secondary metabolites could be exploited for pharmaceutical applications in combination with other drugs. The present review intends to provide adequate tools for studying and developing drug delivery systems based on plant-derived EVs. Therefore, indications concerning extraction methods, characterisation, and drug loading will be offered. Their biological composition and content will also be reported. Finally, the current applications of these systems as nanocarriers for pharmacologically active substances will be shown.

Advancements in Aqueous Two-Phase Systems for Enzyme Extraction, Purification, and Biotransformation

In recent years, the increasing need for energy conservation and environmental protection has driven industries to explore more efficient and sustainable processes. Liquid-liquid extraction (LLE) is a common method used in various sectors for separating components of liquid mixtures. However, the traditional use of toxic solvents poses significant health and environmental risks, prompting the shift toward green solvents. This review deals with the principles, applications, and advantages of aqueous two-phase systems (ATPS) as an alternative to conventional LLE. ATPS, which typically utilize water and nontoxic components, offer significant benefits such as high purity and single-step biomolecule extraction. This paper explores the thermodynamic principles of ATPS, factors influencing enzyme partitioning, and recent advancements in the field. Specific emphasis is placed on the use of ATPS for enzyme extraction, showcasing its potential in improving yields and purity while minimizing environmental impact. The review also highlights the role of ionic liquids and deep eutectic solvents in enhancing the efficiency of ATPS, making them viable for industrial applications. The discussion extends to the challenges of integrating ATPS into biotransformation processes, including enzyme stability and process optimization. Through comprehensive analysis, this paper aims to provide insights into the future prospects of ATPS in sustainable industrial practices and biotechnological applications.

A comprehensive review of engineered exosomes from the preparation strategy to therapeutic applications

Exosomes exhibit high bioavailability, biological stability, targeted specificity, low toxicity, and low immunogenicity in shuttling various bioactive molecules such as proteins, lipids, RNA, and DNA. Natural exosomes, however, have limited production, targeting abilities, and therapeutic efficacy in clinical trials. On the other hand, engineered exosomes have demonstrated long-term circulation, high stability, targeted delivery, and efficient intracellular drug release, garnering significant attention. The engineered exosomes bring new insights into developing next-generation drug delivery systems and show enormous potential in therapeutic applications, such as tumor therapies, diabetes management, cardiovascular disease, and tissue regeneration and repair. In this review, we provide an overview of recent advancements associated with engineered exosomes by focusing on the state-of-the-art strategies for cell engineering and exosome engineering. Exosome isolation methods, including traditional and emerging approaches, are systematically compared along with advancements in characterization methods. Current challenges and future opportunities are further discussed in terms of the preparation and application of engineered exosomes.

Cinnamaldehyde-Treated Bone Marrow Mesenchymal-Stem-Cell-Derived Exosomes via Aqueous Two-Phase System Attenuate IL-1β-Induced Inflammation and Catabolism via Modulation of Proinflammatory Signaling Pathways

Osteoarthritis (OA) is a degenerative joint disorder that is distinguished by inflammation and chronic cartilage damage. Interleukin-1β (IL-1β) is a proinflammatory cytokine that plays an important role in the catabolic processes that underlie the pathogenesis of OA. In this study, we investigate the therapeutic efficacy of exosomes derived from untreated bone-marrow-derived mesenchymal stem cells (BMMSC-Exo) and those treated with cinnamaldehyde (BMMSC-CA-Exo) for preventing the in vitro catabolic effects of IL-1β on chondrocytes. We stimulated chondrocytes with IL-1β to mimic the inflammatory microenvironment of OA. We then treated these chondrocytes with BMMSC-Exo and BMMSC-CA-Exo isolated via an aqueous two-phase system and evaluated their effects on the key cellular processes using molecular techniques. Our findings revealed that treatment with BMMSC-Exo reduces the catabolic effects of IL-1β on chondrocytes and alleviates inflammation. However, further studies directly comparing treatments with BMMSC-Exo and BMMSC-CA-Exo are needed to determine if CA preconditioning can provide additional anti-inflammatory benefits to the exosomes beyond those of CA preconditioning or treatment with regular BMMSC-Exo. Through a comprehensive molecular analysis, we elucidated the regulatory mechanisms underlying this protective effect. We found a significant downregulation of proinflammatory signaling pathways in exosome-infected chondrocytes, suggesting the potential modulation of the NF-κB and MAPK signaling cascades. Furthermore, our study identified the molecular cargo of BMMSC-Exo and BMMSC-CA-Exo, determining the key molecules, such as anti-inflammatory cytokines and cartilage-associated factors, that may contribute to their acquisition of chondroprotective properties. In summary, BMMSC-Exo and BMMSC-CA-Exo exhibit the potential as therapeutic agents for OA by antagonizing the in vitro catabolic effects of IL-1β on chondrocytes. The regulation of the proinflammatory signaling pathways and bioactive molecules delivered by the exosomes suggests a multifaceted mechanism of action. These findings highlight the need for further investigation into exosome-based therapies for OA and joint-related diseases.

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.

Exploring the Potential of Plant-Derived Exosome-like Nanovesicle as Functional Food Components for Human Health: A Review

Plant-derived exosome-like nanovesicles (PELNs) are bilayer membrane-enclosed nanovesicles secreted by plant cells, serving as carriers of various substances such as proteins, RNA, and metabolites. The mounting evidence suggests that PELN plays a crucial role in transmembrane signaling, nutrient transportation, apoptosis, and regulation of gut microbiota composition. This makes it a promising "dark nutrient" for plants to modulate human physiology and pathogenesis. A comprehensive understanding of PELN formation, uptake, and functional mechanisms can offer novel insights into plant nutrition and functional properties, thereby facilitating the precise development of plant-based foods and drugs. This article provides a summary of PELN extraction and characterization, as well as absorption and delivery processes. Furthermore, it focuses on the latest discoveries and underlying physiological mechanisms of PELN's functions while exploring future research directions.

Exploring the role of polymers to overcome ongoing challenges in the field of extracellular vesicles

Extracellular vesicles (EVs) are naturally occurring nanoparticles released from all eucaryotic and procaryotic cells. While their role was formerly largely underestimated, EVs are now clearly established as key mediators of intercellular communication. Therefore, these vesicles constitute an attractive topic of study for both basic and applied research with great potential, for example, as a new class of biomarkers, as cell-free therapeutics or as drug delivery systems. However, the complexity and biological origin of EVs sometimes complicate their identification and therapeutic use. Thus, this rapidly expanding research field requires new methods and tools for the production, enrichment, detection, and therapeutic application of EVs. In this review, we have sought to explain how polymer materials actively contributed to overcome some of the limitations associated to EVs. Indeed, thanks to their infinite diversity of composition and properties, polymers can act through a variety of strategies and at different stages of EVs development. Overall, we would like to emphasize the importance of multidisciplinary research involving polymers to address persistent limitations in the field of EVs.

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.

A survey to evaluate parameters governing the selection and application of extracellular vesicle isolation methods

Extracellular vesicles (EVs) continue to gain interest across the scientific community for diagnostic and therapeutic applications. As EV applications diversify, it is essential that researchers are aware of challenges, in particular the compatibility of EV isolation methods with downstream applications and their clinical translation. We report outcomes of the first cross-comparison study looking to determine parameters (EV source, starting volume, operator experience, application and implementation parameters such as cost and scalability) governing the selection of popular EV isolation methods across disciplines. Our findings highlighted an increased clinical focus, with 36% of respondents applying EVs in therapeutics and diagnostics. Data indicated preferential selection of ultracentrifugation for therapeutic applications, precipitation reagents in clinical settings and size exclusion chromatography for diagnostic applications utilising biofluids. Method selection was influenced by operator experience, with increased method diversity when EV research was not the respondents primary focus. Application and implementation criteria were indicated to be major influencers in method selection, with UC and SEC chosen for their abilities to process large and small volumes, respectively. Overall, we identified parameters influencing method selection across the breadth of EV science, providing a valuable overview of practical considerations for the effective translation of research outcomes.

Comparison of extracellular vesicle isolation processes for therapeutic applications

While extracellular vesicles (EVs) continue to gain interest for therapeutic applications, their clinical translation is limited by a lack of optimal isolation methods. We sought to determine how universally applied isolation methods impact EV purity and yield. EVs were isolated by ultracentrifugation (UC), polyethylene glycol precipitation, Total Exosome Isolation Reagent, an aqueous two-phase system with and without repeat washes or size exclusion chromatography (SEC). EV-like particles could be detected for all isolation methods but varied in their purity and relative expression of surface markers (Alix, Annexin A2, CD9, CD63 and CD81). Assessments of sample purity were dependent on the specificity of characterisation method applied, with total particle counts and particle to protein (PtP) ratios often not aligning with quantitative measures of tetraspanin surface markers obtained using high-resolution nano-flow cytometry. While SEC resulted in the isolation of fewer particles with a relatively low PtP ratio (1.12 × 107 ± 1.43 × 106 vs highest recorded; ATPS/R 2.01 × 108 ± 1.15 × 109, p ⩽ 0.05), EVs isolated using this method displayed a comparatively high level of tetraspanin positivity (e.g. ExoELISA CD63⁺ particles; 1.36 × 1011 ± 1.18 × 1010 vs ATPS/R 2.58 × 1010 ± 1.92 × 109, p ⩽ 0.001). Results originating from an accompanying survey designed to evaluate pragmatic considerations surrounding method implementation (e.g. scalability and cost) identified that SEC and UC were favoured for overall efficiency. However, reservations were highlighted in the scalability of these methods, which could potentially hinder downstream therapeutic applications. In conclusion, variations in sample purity and yield were evident between isolation methods, while standard non-specific assessments of sample purity did not align with advanced quantitative high-resolution analysis of EV surface markers. Reproducible and specific assessments of EV purity will be critical for informing therapeutic studies.

Engineered exosomes for studies in tumor immunology

Exosomes are a type of extracellular vesicle (EV) with diameters of 30-150 nm secreted by most of the cells into the extracellular spaces and can alter the microenvironment through cell-to-cell interactions by fusion with the plasma membrane and subsequent endocytosis and release of the cargo. Because of their biocompatibility, low toxicity and immunogenicity, permeability (even through the blood-brain barrier (BBB)), stability in biological fluids, and ability to accumulate in the lesions with higher specificity, investigators have started making designer's exosomes or engineered exosomes to carry biologically active protein on the surface or inside the exosomes as well as using exosomes to carry drugs, micro RNA, and other products to the site of interest. In this review, we have discussed biogenesis, markers, and contents of various exosomes including exosomes of immune cells. We have also discussed the current methods of making engineered and designer's exosomes as well as the use of engineered exosomes targeting different immune cells in the tumors, stroke, as well as at peripheral blood. Genetic engineering and customizing exosomes create an unlimited opportunity to use in diagnosis and treatment. Very little use has been discovered, and we are far away to reach its limits.

Emerging Role of Edible Exosomes-Like Nanoparticles (ELNs) as Hepatoprotective Agents

Liver diseases are responsible for over 2 million deaths each year and the number is rapidly increasing. There is a strong link between edibles, gut microbiota, liver fat and the liver damage. There are very limited therapeutic options for treatment specifically for Alcoholic liver disease (ALD) and Non-Alcoholic liver disease (NAFLD). Recently, identified Edible Exosomes-like nanoparticles (ELNs) are plant derived membrane bound particles, released by microvesicular bodies for cellular communication and regulate immune responses against many pathogens. Many studies have identified their role as hepatoprotective agent as they carry bioactive material as cargoes which are transferred to recipient cells and affect various biological functions in liver. They are also known to carry specific miRNA, which increases the copy number of beneficial bacteria and the production of lactic acid metabolites in gut and hence restrains from liver injury through portal vein. Few in-vitro studies also have been reported about the anti-inflammatory, anti-oxidant and detoxification properties of ELNs which again protects the liver. The properties such as small size, biocompatibility, stability, low toxicity and non-immunogenicity make ELNs as a better therapeutic option. But, till now, studies on the effect of ELNs as therapeutics are still at its infancy yet promising. Here we discuss about the isolation, characterization, their role in maintaining the gut microbiome and liver homeostasis. Also, we give an outline about the latest advances in ELNs modifications, its biological effects, limitations and we propose the future prospective of ELNs as therapeutics.

Principles and Problems of Exosome Isolation from Biological Fluids

Exosomes, the subclass of small membrane extracellular vesicles, have great diagnostic and therapeutic potential, but the lack of standardized methods for their efficient isolation and analysis limits the introduction of exosomal technologies into clinical practice. This review discusses the problems associated with the isolation of exosomes from biological fluids, as well as the principles of traditional and alternative methods of isolation. The aim of the presented review is to illustrate the variety of approaches based on the physical and biochemical properties of exosomes that can be used for exosome isolation. The advantages and disadvantages of different methods are discussed.

Small but Mighty-Exosomes, Novel Intercellular Messengers in Neurodegeneration

Simple Summary

Exosomes are biological nanoparticles recently recognized as intercellular messengers. They contain a cargo of lipids, proteins, and RNA. They can transfer their content to not only cells in the vicinity but also to cells at a distance. This unique ability empowers them to modulate the physiology of recipient cells. In brain, exosomes play a role in neurodegenerative diseases such as Alzheimer’s disease and Parkinson’s disease and amyotrophic lateral sclerosis.

Abstract

Exosomes of endosomal origin are one class of extracellular vesicles that are important in intercellular communication. Exosomes are released by all cells in our body and their cargo consisting of lipids, proteins and nucleic acids has a footprint reflective of their parental origin. The exosomal cargo has the power to modulate the physiology of recipient cells in the vicinity of the releasing cells or cells at a distance. Harnessing the potential of exosomes relies upon the purity of exosome preparation. Hence, many methods for isolation have been developed and we provide a succinct summary of several methods. In spite of the seclusion imposed by the blood–brain barrier, cells in the CNS are not immune from exosomal intrusive influences. Both neurons and glia release exosomes, often in an activity-dependent manner. A brief description of exosomes released by different cells in the brain and their role in maintaining CNS homeostasis is provided. The hallmark of several neurodegenerative diseases is the accumulation of protein aggregates. Recent studies implicate exosomes’ intercellular communicator role in the spread of misfolded proteins aiding the propagation of pathology. In this review, we discuss the potential contributions made by exosomes in progression of Alzheimer’s disease, Parkinson’s disease, and amyotrophic lateral sclerosis. Understanding contributions made by exosomes in pathogenesis of neurodegeneration opens the field for employing exosomes as therapeutic agents for drug delivery to brain since exosomes do cross the blood–brain barrier.

Pathways and Mechanisms of Cellular Cholesterol Efflux-Insight From Imaging

Cholesterol is an essential molecule in cellular membranes, but too much cholesterol can be toxic. Therefore, mammalian cells have developed complex mechanisms to remove excess cholesterol. In this review article, we discuss what is known about such efflux pathways including a discussion of reverse cholesterol transport and formation of high-density lipoprotein, the function of ABC transporters and other sterol efflux proteins, and we highlight their role in human diseases. Attention is paid to the biophysical principles governing efflux of sterols from cells. We also discuss recent evidence for cholesterol efflux by the release of exosomes, microvesicles, and migrasomes. The role of the endo-lysosomal network, lipophagy, and selected lysosomal transporters, such as Niemann Pick type C proteins in cholesterol export from cells is elucidated. Since oxysterols are important regulators of cellular cholesterol efflux, their formation, trafficking, and secretion are described briefly. In addition to discussing results obtained with traditional biochemical methods, focus is on studies that use established and novel bioimaging approaches to obtain insight into cholesterol efflux pathways, including fluorescence and electron microscopy, atomic force microscopy, X-ray tomography as well as mass spectrometry imaging.

Stimuli-Mediated Specific Isolation of Exosomes from Blood Plasma for High-Throughput Profiling of Cancer Biomarkers

Exosomes, ranging from 30-150 nm in diameter, have emerged as promising non-invasive biomarkers for the diagnosis and prognosis of numerous diseases. However, current research on exosomes is largely restricted by the lack of an efficient method to isolate exosomes from real samples. Herein, the first stimuli-mediated enrichment and purification system to selectively and efficiently extract exosomes from clinical plasma for high-throughput profiling of exosomal mRNAs as cancer biomarkers is presented. This novel isolation system relies on specific installation of the stimuli-responsive copolymers onto exosomal phospholipid bilayers, by which the enrichment and purification are exclusively achieved for exosomes rather than the non-vesicle counterparts co-existing in real samples. The stimuli-mediated isolation system outperforms conventional methods such as ultracentrifugation and polyethylene glycol-based precipitation in terms of isolation yield, purity, and retained bioactivity. The high performance of the isolation system is demonstrated by enriching exosomes from 77 blood plasma samples and validated the clinical potentials in profiling exosomal mRNAs for cancer diagnosis and discrimination with high accuracy. This simple isolation system can boost the development of extracellular vesicle research, not limited to exosomes, in both basic and clinical settings.

Capsule-like DNA Hydrogels with Patterns Formed by Lateral Phase Separation of DNA Nanostructures

Phase separation is a key phenomenon in artificial cell construction. Recent studies have shown that the liquid-liquid phase separation of designed-DNA nanostructures induces the formation of liquid-like condensates that eventually become hydrogels by lowering the solution temperature. As a compartmental capsule is an essential artificial cell structure, many studies have focused on the lateral phase separation of artificial lipid vesicles. However, controlling phase separation using a molecular design approach remains challenging. Here, we present the lateral liquid-liquid phase separation of DNA nanostructures that leads to the formation of phase-separated capsule-like hydrogels. We designed three types of DNA nanostructures (two orthogonal and a linker nanostructure) that were adsorbed onto an interface of water-in-oil (W/O) droplets via electrostatic interactions. The phase separation of DNA nanostructures led to the formation of hydrogels with bicontinuous, patch, and mix patterns, due to the immiscibility of liquid-like DNA during the self-assembly process. The frequency of appearance of these patterns was altered by designing DNA sequences and altering the mixing ratio of the nanostructures. We constructed a phase diagram for the capsule-like DNA hydrogels by investigating pattern formation under various conditions. The phase-separated DNA hydrogels did not only form on the W/O droplet interface but also on the inner leaflet of lipid vesicles. Notably, the capsule-like hydrogels were extracted into an aqueous solution, maintaining the patterns formed by the lateral phase separation. In addition, the extracted hydrogels were successfully combined with enzymatic reactions, which induced their degradation. Our results provide a method for the design and control of phase-separated hydrogel capsules using sequence-designed DNAs. We envision that by incorporating various DNA nanodevices into DNA hydrogel capsules, the capsules will gain molecular sensing, chemical-information processing, and mechanochemical actuating functions, allowing the construction of functional molecular systems.

Therapeutic mesenchymal stromal stem cells: Isolation, characterization and role in equine regenerative medicine and metabolic disorders

Mesenchymal stromal cells (MSC) have become a popular treatment modality in equine orthopaedics. Regenerative therapies are especially interesting for pathologies like complicated tendinopathies of the distal limb, osteoarthritis, osteochondritis dissecans (OCD) and more recently metabolic disorders. Main sources for MSC harvesting in the horse are bone marrow, adipose tissue and umbilical cord blood. While the acquisition of umbilical cord blood is fairly easy and non-invasive, extraction of bone marrow and adipose tissue requires more invasive techniques. Characterization of the stem cells as a result of any isolation method, is also a crucial step for the confirmation of the cells' stemness properties; thus, three main characteristics must be fulfilled by these cells, namely: adherence, expression of a series of well-defined differentiation clusters as well as pluripotency. EVs, resulting from the paracrine action of MSCs, also play a key role in the therapeutic mechanisms mediated by stem cells; MSC-EVs are thus largely implicated in the regulation of proliferation, maturation, polarization and migration of various target cells. Evidence that EVs alone represent a complex network 0involving different soluble factors and could then reflect biophysical characteristics of parent cells has fuelled the importance of developing highly specific techniques for their isolation and analysis. All these aspects related to the functional and technical understanding of MSCs will be discussed and summarized in this review.

Immunostaining Extracellular Vesicles Based on an Aqueous Two-Phase System: For Analysis of Tetraspanins

Immunostaining of extracellular vesicles (EVs) has become necessary for the characterization of EV subtypes, clarification of the EV biogenesis/cellular uptake pathway, drug delivery, etc. Immunostained EVs must be in suspension for further downstream analyses or uses. However, conventional EV immunostaining methods yielding EVs in suspension lack either sufficient recovery or staining specificity because of the washing steps. In this study, we have devised and tested a method to wash immunostained EVs with successive aqueous two-phase system (ATPS) separations. The ATPS is a liquid-liquid extraction procedure that ensures a gentle separation of target molecules. The ATPS has been successfully employed to separate EVs from other impurities with high yield and high purity. Immunostained EVs were washed with the ATPS and compared with other immunostaining methods to confirm the proposed method's high EV recovery and staining accuracy. According to the result, the ATPS-based EV immunostaining method required as low as ∼1 μg without compromise of accuracy and recovery.

Therapeutic and Diagnostic Translation of Extracellular Vesicles in Cardiovascular Diseases: Roadmap to the Clinic

Exosomes are small membrane-bound vesicles of endocytic origin that are actively secreted. The potential of exosomes as effective communicators of biological signaling in myocardial function has previously been investigated, and a recent explosion in exosome research not only underscores their significance in cardiac physiology and pathology, but also draws attention to methodological limitations of studying these extracellular vesicles. In this review, we discuss recent advances and challenges in exosome research with an emphasis on scientific innovations in isolation, identification, and characterization methodologies, and we provide a comprehensive summary of web-based resources available in the field. Importantly, we focus on the biology and function of exosomes, highlighting their fundamental role in cardiovascular pathophysiology to further support potential applications of exosomes as biomarkers and therapeutics for cardiovascular diseases.

Aqueous Two-Phase System (ATPS)-Based Polymersomes for Particle Isolation and Separation

Aqueous two-phase systems (ATPSs) have been widely used in the separation, purification, and enrichment of biomolecules for their excellent biocompatibility. While ultracentrifugation and microfluidic devices have been combined with ATPS to facilitate the separation of biomolecules and achieve high recovery yields, they often lack the ability to effectively isolate and separate biomolecules in low concentrations. In this work, we present a strategy that leverages the preferential partitioning of biomolecules in ATPS droplets to efficiently separate model extracellular vesicle (EV) particles. We demonstrate that the additional oil phase between the inner ATPS droplets and the aqueous continuous phase in triple emulsion droplets resolves the size controllability and instability issues of ATPS droplets, enabling the production of highly monodisperse ATPS-based polymersomes with enhanced stability for effective isolation of ATPS droplets from the surrounding environment. Furthermore, we achieve separation of model EV particles in a single dextran (DEX)-rich droplet by the massive production of ATPS-based polymersomes and osmotic-pressure-induced rupture of the selected polymersome in a hypertonic solution composed of poly(ethylene glycol) (PEG).

Isolation of extracellular vesicles from small volumes of plasma using a microfluidic aqueous two-phase system

As conventional bulky methods for extracellular vesicle (EV) separation are unsuitable for small volumes of samples, microfluidic devices are thought to offer a solution for the integrated and automatic processing of EV separation. This study demonstrates a simple microfluidic aqueous two-phase system (ATPS) for EV separation with high recovery efficiency to overcome the limitation of previous devices, which require complex external equipment or high cost manufacturing. With polyethylene glycol and dextran in the microfluidic channel, the isolation mechanism of the microfluidic ATPS was analyzed by comparison between two-phase and one-phase systems. Our device could facilitate continuous EV isolation with 83.4% recovery efficiency and remove 65.4% of the proteins from the EV-protein mixture. EVs were also successfully isolated from human plasma at high recovery efficiency.

Nanoparticles from Equine Fetal Bone Marrow-Derived Cells Enhance the Survival of Injured Chondrocytes

Simple Summary

Reports on the potential of using mesenchymal stem cells (MSCs) for treating equine degenerative joint diseases have been increasing over the past few years, in spite of limitations such as uncontrolled differentiation, immunogenicity, and tumorigenicity. We elucidated an allogenic alternative, where equine bone marrow-derived cells (BMC)-derived nanoparticles (BMC-NPs) can be used to promote the growth of chondrocytes, and simultaneously reduce their cytokine-induced apoptosis. The role of BMC-NPs in activation of signaling pathway molecules was also established.

Abstract

Recent studies have shown that mesenchymal stem cells (MSCs) can play a restorative role against degenerative joint diseases in horses. The purpose of this study was to investigate whether fetal bone marrow-derived cells (BMC)-derived nanoparticles (BMC-NPs) can stimulate the survival of equine chondrocytes. Equine fetal BMCs were isolated and characterized, and the role of BMC-NPs s in equine chondrocytes undergoing inflammatory cell death was examined. BMCs have several characteristics, such as the potential to differentiate into chondrocytes and osteocytes. Additionally, BMCs expressed immunoregulatory genes in response to treatment with tumor necrosis factor-alpha (TNF-α) and Interleukin 1 beta (IL-1β). We found that BMC-NPs were taken up by equine chondrocytes. Functionally, BMC-NPs promoted the growth of chondrocytes, and reduced apoptosis induced by inflammatory cytokines. Furthermore, we observed that BMC-NPs upregulated the phosphorylation of protein kinase B (Akt) in the presence of IL-1β, and reduced the phosphorylation of TNF-α-induced activation of extracellular signal-regulated kinase 1/2 (ERK1/2) in the chondrocytes. Cumulatively, our study demonstrated that equine fetal BMC-NPs have the potential to stimulate the survival of chondrocytes damaged by inflammatory cytokines. Thus, BMC-NPs may become an alternative cell-free allogenic therapeutic for degenerative joint diseases in horses.

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

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

The Application of MSCs-Derived Extracellular Vesicles in Bone Disorders: Novel Cell-Free Therapeutic Strategy

Bone is crucial for supporting the body, protecting other organs, providing minerals, and secreting hormone to regulate other organ's function. Bone disorders result in pain and disability, severely affecting human health, reducing the quality of life and increasing costs to society. With the rapid increase in the aging population worldwide, bone disorders have become one major disease. As a result, efficacious therapies of bone disorders have become the focus of attention worldwide. Mesenchymal stem cells (MSCs) have been widely explored as a new therapeutic method for numerous diseases. Recent evidence suggests that the therapeutic effects of MSCs are mainly mediated by their extracellular vesicles (EV). MSCs-derived extracellular vesicles (MSCs-EV) is indicated as a novel cell-free alternative to cell therapy with MSCs in regenerative medicine. Here, we review the current knowledge of EV and highlight the application studies of MSCs-EV in bone disorders by focusing on osteoarthritis (OA), rheumatoid arthritis (RA), osteoporosis (OP), and bone fracture. Moreover, we discuss the key issues and perspectives of MSCs-EV as a clinical therapeutic strategy for bone diseases.

THE PRESENT AND FUTURE OF THE MASS SPECTROMETRY-BASED INVESTIGATION OF THE EXOSOME LANDSCAPE

Exosomes are critical intercellular messengers released upon the fusion of multivesicular bodies with the cellular plasma membrane that deliver their cargo in the form of extracellular vesicles. Containing numerous nonrandomly packed functional proteins, lipids, and RNAs, exosomes are vital intercellular messengers that contribute to the physiologic processes of the healthy organism. During the post-genome era, exosome-oriented proteomics have garnered great interest. Since its establishment, mass spectrometry (MS) has been indispensable for the field of proteomics research and has advanced rapidly to interrogate biological samples at a higher resolution and sensitivity. Driven by new methodologies and more advanced instrumentation, MS-based approaches have revolutionized our understanding of protein biology. As the access to online proteomics database platforms has blossomed, experimental data processing occurs with more speed and accuracy. Here, we review recent advances in the technological progress of MS-based proteomics and several new detection strategies for MS-based proteomics research. We also summarize the use of integrated online databases for proteomics research in the era of big data. © 2020 John Wiley & Sons Ltd. Mass Spec Rev.

The Role of Bacterial Membrane Vesicles in the Dissemination of Antibiotic Resistance and as Promising Carriers for Therapeutic Agent Delivery

The rapid emergence and spread of antibiotic-resistant bacteria continues to be an issue difficult to deal with, especially in the clinical, animal husbandry, and food fields. The occurrence of multidrug-resistant bacteria renders treatment with antibiotics ineffective. Therefore, the development of new therapeutic methods is a worthwhile research endeavor in treating infections caused by antibiotic-resistant bacteria. Recently, bacterial membrane vesicles (BMVs) have been investigated as a possible approach to drug delivery and vaccine development. The BMVs are released by both pathogenic and non-pathogenic Gram-positive and Gram-negative bacteria, containing various components originating from the cytoplasm and the cell envelope. The BMVs are able to transform bacteria with genes that encode enzymes such as proteases, glycosidases, and peptidases, resulting in the enhanced antibiotic resistance in bacteria. The BMVs can increase the resistance of bacteria to antibiotics. However, the biogenesis and functions of BMVs are not fully understood in association with the bacterial pathogenesis. Therefore, this review aims to discuss BMV-associated antibiotic resistance and BMV-based therapeutic interventions.

Urinary extracellular vesicles: Origin, role as intercellular messengers and biomarkers; efficient sorting and potential treatment options

Urinary extracellular vesicles (uEVs) are a heterogenous group of vesicles consisting mainly of microvesicles and exosomes that originate predominantly (99.96%) from kidney, the urinary tract epithelium and the male reproductive tract. Secreted EVs contain molecular cargo from parental cells and provide an attractive source for biomarkers, a potential readout of physiological and pathophysiological mechanisms, and events associated with the urinary system. uEVs are readily enriched and isolated from urine samples and we review 6 standard methods that allow for downstream analysis of the uEV cargo. Although the use of uEVs as a surrogate readout for physiological changes in tissue protein levels is widespread, the protein abundance in uEVs is affected significantly by mechanisms that regulate protein sorting and secretion in uEVs. Data suggest that baseline kidney tissue and uEV levels of apical membrane-associated electrolyte transport proteins are not directly related in human patients. Recent evidence indicates that EVs may contribute to physiological and pathophysiological intercellular signalling and EVs confer protection against renal ischemia-reperfusion injury. The therapeutic use of EVs as information carriers has mainly been explored in vitro and a major hurdle lies in the translation of the in vitro findings into an in vivo setting. Thus, the EV research field is moving from a technical focus to a more physiological focus, allowing for a deeper understanding of human physiology, development of diagnostic tools and potential treatment strategies for precision medicine.

Optimized Isolation of Extracellular Vesicles From Various Organic Sources Using Aqueous Two-Phase System

From biomarkers to drug carriers, Extracellular Vesicles (EVs) are being used successfully in numerous applications. However, while the subject has been steadily rising in popularity, current methods of isolating EVs are lagging behind, incapable of isolating EVs at a high enough quantity or quality while also requiring expensive, specialized equipment. The “isolation problem” is one of the major obstacles in the field of EV research - and even more so for their potential, widespread use for clinical diagnosis and therapeutic applications. Aqueous Two-Phase Systems (ATPS) has been reported previously as a promising method for isolating EVs quickly and efficiently, and with little contaminants - however, this method has not seen widespread use. In this study, an ATPS-based isolation protocol is used to isolate small EVs from plant, cell culture, and parasite culture sources. Isolated EVs were characterized in surface markers, size, and morphological manner. Additionally, the capacity of ATPS-based EV isolation in removing different contaminants was shown by measuring protein, fatty acid, acid, and phenol red levels of the final isolate. In conclusion, we have shown that EVs originating from different biological sources can be isolated successfully in a cost-effective and user-friendly manner with the use of aqueous two-phase systems.

The importance of extracellular vesicle purification for downstream analysis: A comparison of differential centrifugation and size exclusion chromatography for helminth pathogens

BACKGROUND

Robust protocols for the isolation of extracellular vesicles (EVs) from the rest of their excretory-secretory products are necessary for downstream studies and application development. The most widely used purification method of EVs for helminth pathogens is currently differential centrifugation (DC). In contrast, size exclusion chromatography (SEC) has been included in the purification pipeline for EVs from other pathogens, highlighting there is not an agreed research community 'gold standard' for EV isolation. In this case study, Fasciola hepatica from natural populations were cultured in order to collect EVs from culture media and evaluate a SEC or DC approach to pathogen helminth EV purification.

METHODOLOGY/PRINCIPAL FINDINGS

Transmission electron and atomic force microscopy demonstrated that EVs prepared by SEC were both smaller in size and less diverse than EV resolved by DC. Protein quantification and Western blotting further demonstrated that SEC purification realised a higher EV purity to free excretory-secretory protein (ESP) yield ratio compared to DC approaches as evident by the reduction of soluble free cathepsin L proteases in SEC EV preparations. Proteomic analysis further highlighted DC contamination from ESP as shown by an increased diversity of protein identifications and unique peptide hits in DC EVs as compared to SEC EVs. In addition, SEC purified EVs contained less tegumental based proteins than DC purified EVs.

CONCLUSIONS/SIGNIFICANCE

The data suggests that DC and SEC purification methods do not isolate equivalent EV population profiles and caution should be taken in the choice of EV purification utilised, with certain protocols for DC preparations including more free ES proteins and tegumental artefacts. We propose that SEC methods should be used for EV purification prior to downstream studies.

Roles and Regulation of Extracellular Vesicles in Cardiovascular Mineral Metabolism

Cardiovascular calcification is a multifaceted disease that is a leading independent predictor of cardiovascular morbidity and mortality. Recent studies have identified a calcification-prone population of extracellular vesicles as the putative elementary units of vascular microcalcification in diseased heart valves and vessels. Their action is highly context-dependent; extracellular vesicles released by smooth muscle cells, valvular interstitial cells, endothelial cells, and macrophages may promote or inhibit mineralization, depending on the phenotype of their originating cells and/or the extracellular environment to which they are released. In particular, emerging roles for vesicular microRNAs, bioactive lipids, metabolites, and protein cargoes in driving this pro-calcific switch underpin the necessity of innovative strategies to employ next-generation sequencing and omics technologies in order to better understand the pathobiology of these nano-sized entities. Furthermore, a recent body of work has emerged that centers on the novel re-purposing of extracellular vesicles and exosomes as potential therapeutic avenues for cardiovascular calcification. This review aims to highlight the role of extracellular vesicles as constituents of cardiovascular calcification and summarizes recent advances in our understanding of the biophysical nature of vesicle accumulation, aggregation, and mineralization. We also comprehensively discuss the latest evidence that extracellular vesicles act as key mediators and regulators of cell/cell communication, osteoblastic/osteoclastic differentiation, and cell/matrix interactions in cardiovascular tissues. Lastly, we highlight the importance of robust vesicle isolation and characterization when studying these phenomena, and offer a brief primer on working with cardiovascular applications of extracellular vesicles.

Toward Exosome-Based Neuronal Diagnostic Devices

Targeting exosome for liquid biopsy has gained significant attention for its diagnostic and therapeutic potential. For detecting neuronal disease diagnosis such as Alzheimer's disease (AD), the main technique for identifying AD still relies on positron-emission tomography (PET) imaging to detect the presence of amyloid-β (Aβ). While the detection of Aβ in cerebrospinal fluid has also been suggested as a marker for AD, the lack of quantitative measurements has compromised existing assays. In cerebrospinal fluid, in addition to Aβ, T-Tau, and P-Tau, alpha-synuclein has been considered a biomarker of neurodegeneration. This review suggests that and explains how the exosome can be used as a neuronal diagnostic component. To this end, we summarize current progress in exosome preparation/isolation and quantification techniques and comment on the outlooks for neuronal exosome-based diagnostic techniques.

Salivary Exosomes: Emerging Roles in Systemic Disease

Saliva, which contains biological information, is considered a valuable diagnostic tool for local and systemic diseases and conditions because, similar to blood, it contains important molecules like DNA, RNA, and proteins. Exosomes are cell-derived vesicles 30-100 nm in diameter with substantial biological functions, including intracellular communication and signalling. These vesicles, which are present in bodily fluids, including saliva, are released upon fusion of multivesicular bodies (MVBs) with the cellular plasma membrane. Salivary diagnosis has notable advantages, which include noninvasiveness, ease of collection, absence of coagulation, and a similar content as plasma, as well as increased patient compliance compared to other diagnostic approaches. However, investigation of the roles of salivary exosomes is still in its early years. In this review, we first describe the characteristics of endocytosis and secretion of salivary exosomes, as well as database and bioinformatics analysis of exosomes. Then, we describe strategies for the isolation of exosomes from human saliva and the emerging role of salivary exosomes as potential biomarkers of oral and other systemic diseases. Given the ever-growing role of salivary exosomes, defining their functions and understanding their specific mechanisms will provide novel insights into possible applications of salivary exosomes in the diagnosis and treatment of systemic diseases.

Purification of bacterial inulinase in aqueous two-phase systems

In this study, extracellular inulinase from Bacillus sp. 11/3 was partially purified and concentrated using aqueous two-phase system (ATPS). Two different phase forming salts and four types of polyethylene glycol (PEG) were used. Binodal curves and tie-length lines (TLLs) for eight ATPS were developed. For inulinase purification, concentrations of PEG and salt according to binodal curves (between 17 and 26%) were chosen. All ATPSs for inulinase purification were characterized. An ATPS consisted of 26% PEG1000 and 26% MgSO₄ was found to be the most suitable for inulinase purification. This ATPS has 28.47% TLL, 1.03 of volume ratio, purification factor of 4.65 fold and recovery yield of 66.17%. On the SDS-PAGE electrophoresis two protein bands with molecular weight of around 24 and 56 kDa were observed. The partially purified enzymes had optimal activity at pH 8.0 and 6.5, optimal temperature at 30 and 70°C and kinetic parameters K_m = 26.32 mmol and V_max = 526 mmol/min.

Aqueous two-phase system to isolate extracellular vesicles from urine for prostate cancer diagnosis

Analyzing extracellular vesicles (EVs) is an attractive approach to diagnosis of prostate diagnosis. However, existing methods of EVs isolation have low efficiency, purity, and long process time, and therefore have low diagnostic ability. To solve these the problems, a two-phase system is adapted to isolate EVs from a patient’s urine. Urine from 20 prostate cancer (PCA) patients and 10 benign prostate hyperplasia patients was used to quantify the EVs-isolation ability of an aqueous two-phase system (ATPS) and to compare the diagnostic ability of ATPS with that of the conventional diagnosis method. An optimized ATPS isolates EVs with ~100% efficiency within ~30 min, with 14 times as high as achieved by ultracentrifugation. Afterward, PCR and ELISA are used to detect EVs derived from PCA cells in urine. The results demonstrate that diagnostic ability based on ATPS is better than other conventional diagnostic methods. ATPS can obtain a high quality and quantity of EVs from patients’ urine. EVs contain cancer-related protein and genes, so these abundant sources enable diagnosis with high specificity and sensitivity. Therefore, ATPS is a useful tool to increase the specificity and sensitivity of diagnosis.

Emerging Biotechnology Applications of Aqueous Two-Phase Systems

Liquid-liquid phase separation between aqueous solutions containing two incompatible polymers, a polymer and a salt, or a polymer and a surfactant, has been exploited for a wide variety of biotechnology applications throughout the years. While many applications for aqueous two-phase systems fall within the realm of separation science, the ability to partition many different materials within these systems, coupled with recent advances in materials science and liquid handling, has allowed bioengineers to imagine new applications. This progress report provides an overview of the history and key properties of aqueous two-phase systems to lend context to how these materials have progressed to modern applications such as cellular micropatterning and bioprinting, high-throughput 3D tissue assembly, microscale biomolecular assay development, facilitation of cell separation and microcapsule production using microfluidic devices, and synthetic biology. Future directions and present limitations and design considerations of this adaptable and promising toolkit for biomolecule and cellular manipulation are further evaluated.

Isolation of Extracellular Vesicles: General Methodologies and Latest Trends

BACKGROUND

Extracellular vesicles (EVs) play an essential role in the communication between cells and transport of diagnostically significant molecules. A wide diversity of approaches utilizing different biochemical properties of EVs and a lack of accepted protocols make data interpretation very challenging.

SCOPE OF REVIEW

This review consolidates the data on the classical and state-of-the-art methods for isolation of EVs, including exosomes, highlighting the advantages and disadvantages of each method. Various characteristics of individual methods, including isolation efficiency, EV yield, properties of isolated EVs, and labor consumption are compared.

MAJOR CONCLUSIONS

A mixed population of vesicles is obtained in most studies of EVs for all used isolation methods. The properties of an analyzed sample should be taken into account when planning an experiment aimed at studying and using these vesicles. The problem of adequate EVs isolation methods still remains; it might not be possible to develop a universal EV isolation method but the available protocols can be used towards solving particular types of problems.

GENERAL SIGNIFICANCE

With the wide use of EVs for diagnosis and therapy of various diseases the evaluation of existing methods for EV isolation is one of the key problems in modern biology and medicine.

Methodological Guidelines to Study Extracellular Vesicles

Owing to the relationship between extracellular vesicles (EVs) and physiological and pathological conditions, the interest in EVs is exponentially growing. EVs hold high hopes for novel diagnostic and translational discoveries. This review provides an expert-based update of recent advances in the methods to study EVs and summarizes currently accepted considerations and recommendations from sample collection to isolation, detection, and characterization of EVs. Common misconceptions and methodological pitfalls are highlighted. Although EVs are found in all body fluids, in this review, we will focus on EVs from human blood, not only our most complex but also the most interesting body fluid for cardiovascular research.

Proteomic analysis of exosomal cargo: the challenge of high purity vesicle isolation

The re-discovery of exosomes as intercellular messengers with high potential for diagnostic and therapeutic utility has led to them becoming a popular topic of research in recent years. One of the essential research areas in this field is the characterization of exosomal cargo, which includes numerous non-randomly packed proteins and nucleic acids. Unexpectedly, a very challenging aspect of exploration of extracellular vesicles has turned out to be their effective and selective isolation. The plurality of developed protocols leads to qualitative and quantitative variability in terms of the obtained exosomes, which significantly affects the results of downstream analyses and makes them difficult to compare, reproduce and interpret between research groups. Currently, there is a general consensus among the exosome-oriented community concerning the urgent need for the optimization and standardization of methods employed for the purification of these vesicles. Hence, we review here several strategies for exosome preparation including ultracentrifugation, chemical precipitation, affinity capturing and filtration techniques. The advantages and disadvantages of different approaches are discussed with special emphasis being placed on their adequacy for proteomics applications, which are particularly sensitive to sample quality. We conclude that certain methods, exemplified by ultracentrifugation combined with iodixanol density gradient centrifugation or gel filtration, although labor-intensive, provide superior quality exosome preparations suitable for reliable analysis by mass spectrometry.

RNA in Salivary Extracellular Vesicles as a Possible Tool for Systemic Disease Diagnosis

Saliva contains biological information as blood and is recognized as a valuable diagnostic medium for their noninvasiveness. Although "-omics" researches have tried to investigate saliva, the origin and significance of its contents are not clear, and its usage is largely confined to oral disease in the diagnostic and prognostic field. In an attempt to broaden the applicability of saliva and to find systemic disease-derived RNA in saliva, we made mouse models that had human melanoma and isolated extracellular vesicles (EVs) from their saliva by an aqueous 2-phase system (ATPS), then identified and evaluated their expression of human melan-A RNA, which is associated with melanoma on skin. With ATPS, EVs were isolated efficiently and stably while taking less time compared to isolation by ultracentrifugation. When ATPS was used to isolate EVs from saliva, the mean ± SD percentage of EVs recovered from initial EVs was 38.22% ± 18.55% by the number of particles, and the mean ± SD percentage of RNA recovered from the initial amount was 60.33% ± 5.34%. RNAs within isolated EVs were analyzed subsequently by reverse transcription quantitative polymerase chain reaction and polymerase chain reaction from saliva and plasma. In melanoma mice, amplification of human melan-A was identified from saliva and plasma, even though a relative amount of normalized melan-A was lower than that of plasma. These results present a possibility that RNAs derived from systemic disease are transferred into saliva from blood in EVs. Also, they suggest that saliva could be exploited in obtaining information about systemic disease, not only about oral disease, by examining RNAs in EVs from saliva instead of blood.