Separation of distinct exosome subpopulations: isolation and characterization approaches and their associated challenges

Harnessing exosomes and plant-derived exosomes as nanocarriers for the efficient delivery of plant bioactives

Exosomes, a category of extracellular vesicle (EV), are phospholipid bilayer structures ranging from 30 to 150 nm, produced by various organisms through the endosomal pathway. Recent studies have established the utilization of exosomes as nanocarriers for drug distribution across various therapeutic areas including cancer, acute liver injury, neuroprotection, oxidative stress, inflammation, etc. The importance of plant-derived exosomes and exosome vesicles derived from mammalian cells or milk, loaded with potent plant bioactives for various therapeutic indications are discussed along with insights into future perspectives. Moreover, this review provides a detailed understanding of exosome biogenesis, their composition, classification, stability of different types of exosomes, and different routes of administration along with the standard techniques used for isolating, purifying, and characterizing exosomes.

Label-free single-vesicle based surface enhanced Raman spectroscopy: A robust approach for investigating the biomolecular composition of small extracellular vesicles

Small extracellular vesicles (sEVs) are cell-released vesicles ranging from 30-150nm in size. They have garnered increasing attention because of their potential for both the diagnosis and treatment of disease. The diversity of sEVs derives from their biological composition and cargo content. Currently, the isolation of sEV subpopulations is primarily based on bio-physical and affinity-based approaches. Since a standardized definition for sEV subpopulations is yet to be fully established, it is important to further investigate the correlation between the biomolecular composition of sEVs and their physical properties. In this study, we employed a platform combining single-vesicle surface-enhanced Raman spectroscopy (SERS) and machine learning to examine individual sEVs isolated by size-exclusion chromatography (SEC). The biomolecular composition of each vesicle examined was reflected by its corresponding SERS spectral features (biomolecular "fingerprints"), with their roots in the composition of their collective Raman-active bonds. Origins of the SERS spectral features were validated through a comparative analysis between SERS and mass spectrometry (MS). SERS fingerprinting of individual vesicles was effective in overcoming the challenges posed by EV population averaging, allowing for the possibility of analyzing the variations in biomolecular composition between the vesicles of similar and/or different sizes. Using this approach, we uncovered that each of the size-based fractions of sEVs contained particles with predominantly similar SERS spectral features. Indeed, more than 84% of the vesicles residing within a particular group were clearly distinguishable from that of the other EV sub-populations, despite some spectral variations within each sub-population. Our results suggest the possibility that size-based EV fractionation methods produce samples where similarly eluted sEVs are correlated with their respective biochemical contents, as reflected by their SERS spectra. Our findings therefore highlight the possibility that the biogenesis and respective biological functionalities of the various sEV fractions may be inherently different.

Proteomic profiling of mesenchymal stem cell-derived extracellular vesicles: Impact of isolation methods on protein cargo

Extracellular vesicles (EVs) are nanosized vesicles with a lipid bilayer that are secreted by cells and play a critical role in cell-to-cell communication. Despite the promising reports regarding their diagnostic and therapeutic potential, the utilization of EVs in the clinical setting is limited due to insufficient information about their cargo and a lack of standardization in isolation and analysis methods. Considering protein cargos in EVs as key contributors to their therapeutic potency, we conducted a tandem mass tag (TMT) quantitative proteomics analysis of three subpopulations of mesenchymal stem cell (MSC)-derived EVs obtained through three different isolation techniques: ultracentrifugation (UC), high-speed centrifugation (HS), and ultracentrifugation on sucrose cushion (SU). Subsequently, we checked EV marker expression, size distribution, and morphological characterization, followed by bioinformatic analysis. The bioinformatic analysis of the proteome results revealed that these subpopulations exhibit distinct molecular and functional characteristics. The choice of isolation method impacts the proteome of isolated EVs by isolating different subpopulations of EVs. Specifically, EVs isolated through the high-speed centrifugation (HS) method exhibited a higher abundance of ribosomal and mitochondrial proteins. Functional apoptosis assays comparing isolated mitochondria with EVs isolated through different methods revealed that HS-EVs, but not other EVs, induced early apoptosis in cancer cells. On the other hand, EVs isolated using the sucrose cushion (SU) and ultracentrifugation (UC) methods demonstrated a higher abundance of proteins primarily involved in the immune response, cell-cell interactions and extracellular matrix interactions. Our analyses unveil notable disparities in proteins and associated biological functions among EV subpopulations, underscoring the importance of meticulously selecting isolation methods and resultant EV subpopulations based on the intended application.

Increasing the sensitivity and accuracy of detecting exosomes as biomarkers for cancer monitoring using optical nanobiosensors

The advancement of nanoscience and material design in recent times has facilitated the creation of point-of-care devices for cancer diagnosis and biomolecule sensing. Exosomes (EXOs) facilitate the transfer of bioactive molecules between cancer cells and diverse cells in the local and distant microenvironments, thereby contributing to cancer progression and metastasis. Specifically, EXOs derived from cancer are likely to function as biomarkers for early cancer detection due to the genetic or signaling alterations they transport as payload within the cancer cells of origin. It has been verified that EXOs circulate steadily in bodily secretions and contain a variety of information that indicates the progression of the tumor. However, acquiring molecular information and interactions regarding EXOs has presented significant technical challenges due to their nanoscale nature and high heterogeneity. Colorimetry, surface plasmon resonance (SPR), fluorescence, and Raman scattering are examples of optical techniques utilized to quantify cancer exosomal biomarkers, including lipids, proteins, RNA, and DNA. Many optically active nanoparticles (NPs), predominantly carbon-based, inorganic, organic, and composite-based nanomaterials, have been employed in biosensing technology. The exceptional physical properties exhibited by nanomaterials, including carbon NPs, noble metal NPs, and magnetic NPs, have facilitated significant progress in the development of optical nanobiosensors intended for the detection of EXOs originating from tumors. Following a summary of the biogenesis, biological functions, and biomarker value of known EXOs, this article provides an update on the detection methodologies currently under investigation. In conclusion, we propose some potential enhancements to optical biosensors utilized in detecting EXO, utilizing various NP materials such as silicon NPs, graphene oxide (GO), metal NPs, and quantum dots (QDs).

Insights into optimizing exosome therapies for acute skin wound healing and other tissue repair

Exosome therapy holds great promise as a novel approach to improve acute skin wound healing. This review provides a comprehensive overview of the current understanding of exosome biology and its potential applications in acute skin wound healing and beyond. Exosomes, small extracellular vesicles secreted by various stem cells, have emerged as potent mediators of intercellular communication and tissue repair. One advantage of exosome therapy is its ability to avoid potential risks associated with stem cell therapy, such as immune rejection or stem cells differentiating into unwanted cell types. However, further research is necessary to optimize exosome therapy, not only in the areas of exosome isolation, characterization, and engineering, but also in determining the optimal dose, timing, administration, and frequency of exosome therapy. Thus, optimization of exosome therapy is critical for the development of more effective and safer exosome-based therapies for acute skin wound healing and other diseases induced by cancer, ischemia, or inflammation. This review provides valuable insights into the potential of exosome therapy and highlights the need for further research to optimize exosome therapy for clinical use.

Exosome-mediated tumor metastasis: Biology, molecular targets and immuno-therapeutic options

Small extracellular vesicles called exosomes play a crucial part in promoting intercellular communication. They act as intermediaries for the exchange of bioactive chemicals between cells, released into the extracellular milieu by a variety of cell types. Within the context of cancer progression, metastasis is a complex process that plays a significant role in the spread of malignant cells from their main site of origin to distant anatomical locations. This complex process plays a key role in the domain of cancer-related deaths. In summary, the trajectory of current research in the field of exosome-mediated metastasis is characterized by its unrelenting quest for more profound understanding of the molecular nuances, the development of innovative diagnostic tools and therapeutic approaches, and the unwavering dedication to transforming these discoveries into revolutionary clinical applications. This unrelenting pursuit represents a shared desire to improve the prognosis for individuals suffering from metastatic cancer and to nudge the treatment paradigm in the direction of more effective and customized interventions.

Exploiting Sound for Emerging Applications of Extracellular Vesicles

Extracellular vesicles are nano- to microscale, membrane-bound particles released by cells into extracellular space, and act as carriers of biomarkers and therapeutics, holding promising potential in translational medicine. However, the challenges remain in handling and detecting extracellular vesicles for disease diagnosis as well as exploring their therapeutic capability for disease treatment. Here, we review the recent engineering and technology advances by leveraging the power of sound waves to address the challenges in diagnostic and therapeutic applications of extracellular vesicles and biomimetic nanovesicles. We first introduce the fundamental principles of sound waves for understanding different acoustic-assisted extracellular vesicle technologies. We discuss the acoustic-assisted diagnostic methods including the purification, manipulation, biosensing, and bioimaging of extracellular vesicles. Then, we summarize the recent advances in acoustically enhanced therapeutics using extracellular vesicles and biomimetic nanovesicles. Finally, we provide perspectives into current challenges and future clinical applications of the promising extracellular vesicles and biomimetic nanovesicles powered by sound.

A state-of-the-art review of the recent advances in exosome isolation and detection methods in viral infection

Proteins, RNA, DNA, lipids, and carbohydrates are only some of the molecular components found in exosomes released by tumor cells. They play an essential role in healthy and diseased cells as messengers of short- and long-distance intercellular communication. However, since exosomes are released by every kind of cell and may be found in blood and other bodily fluids, they may one day serve as biomarkers for a wide range of disorders. In many pathological conditions, including cancer, inflammation, and infection, they play a role. It has been shown that the biogenesis of exosomes is analogous to that of viruses and that the exosomal cargo plays an essential role in the propagation, dissemination, and infection of several viruses. Bidirectional modulation of the immune response is achieved by the ability of exosomes associated with viruses to facilitate immunological escape and stimulate the body's antiviral immune response. Recently, exosomes have received a lot of interest due to their potential therapeutic use as biomarkers for viral infections such as human immunodeficiency virus (HIV), Hepatitis B virus (HBV), Hepatitis C virus (HCV), Epstein-Barr virus (EBV), and SARS-CoV-2. This article discusses the purification procedures and detection techniques for exosomes and examines the research on exosomes as a biomarker of viral infection.

Optimized procedure for high-throughput transcriptome profiling of small extracellular vesicles isolated from low volume serum samples

OBJECTIVES

Small extracellular vesicles (EVs) contain various signaling molecules, thus playing a crucial role in cell-to-cell communication and emerging as a promising source of biomarkers. However, the lack of standardized procedures impedes their translation to clinical practice. Thus, we compared different approaches for high-throughput analysis of small EVs transcriptome.

METHODS

Small EVs were isolated from 150 μL of serum. Quality and quantity were assessed by dynamic light scattering, transmission electron microscopy, and Western blot. Comparison of RNA extraction efficiency was performed, and expression of selected genes was analyzed by RT-qPCR. Whole transcriptome analysis was done using microarrays.

RESULTS

Obtained data confirmed the suitability of size exclusion chromatography for isolation of small EVs. Analyses of gene expression showed the best results in case of samples isolated by Monarch Total RNA Miniprep Kit. Totally, 7,182 transcripts were identified to be deregulated between colorectal cancer patients and healthy controls. The majority of them were non-coding RNAs with more than 70 % being lncRNAs, while protein-coding genes represented the second most common gene biotype.

CONCLUSIONS

We have optimized the protocol for isolation of small EVs and their RNA from low volume of sera and confirmed the suitability of Clariom D Pico Assays for transcriptome profiling.

Thermosensitive Capturer Coupled with the CD63 Aptamer for Highly Efficient Isolation of Exosomes

Exosomes are bioactive substances secreted by various cells that play a crucial role in cell communication. Due to their nanoscale size and interference from nonexosome proteins, the rapid capture and nondestructive release of exosomes remain a technical challenge which significantly hinders their biomedical application. To overcome this obstacle, we have designed a CD63 aptamer-based thermosensitive copolymer for the effective isolation of exosomes from mesenchymal stem cells (MSCs). A thermal-responsive copolymer, poly(N-isopropylacrylamide-co-butyl methacrylate-co-N-hydroxysuccinimide methacrylate) P(NIPAM-co-BMA-co-NHSMA, PNB), was prepared, which could realize reversible hydrophilic/hydrophobic phase transition by varying temperature. Then, CD63 aptamers were further modified to the copolymer to form the PNB-aptamer, where the aptamer units, acting as a "lock and key", specifically bind exosomes. Under the low critical solution temperature (LCST) of the PNB-aptamer, it can maintain a hydrophilic state, capturing exosomes from the cell culture medium. Subsequently, exosome-carrying PNB-aptamers can endure from hydrophilic to hydrophobic phase transition by increasing the temperature above its LCST, and then they can be collected after centrifugation. By introducing the complementary sequence of the CD63 aptamer, the stronger binding affinity between the complementary sequence and the aptamers facilitates the release of exosomes from the PNB-aptamer. The yield of exosome samples captured from a MSC culture medium by the PNB-aptamer system (around 62%) is considerably higher than that obtained by the current "gold standard" ultrafiltration (UC) approach (around 42%). Thus, the PNB-aptamer capturer provides a potential strategy for highly efficient exosome isolation.

Novel insights into the isolation of extracellular vesicles by anion exchange chromatography

Extracellular vesicles (EVs) are membrane structures enclosed by a lipid bilayer that are released into the extracellular space by all types of cells. EVs are involved in many physiological processes by transporting biologically active substances. Interest in EVs for diagnostic biomarker research and therapeutic drug delivery applications has increased in recent years. The realization of the full therapeutic potential of EVs is currently hampered by the lack of a suitable technology for the isolation and purification of EVs for downstream pharmaceutical applications. Anion Exchange Chromatography (AEX) is an established method in which specific charges on the AEX matrix can exploit charges on the surface of EVs and their interactions to provide a productive and scalable separation and purification method. The established AEX method using Eshmuno® Q, a strong tentacle anion exchange resin, was used to demonstrate the principal feasibility of AEX-based isolation and gain insight into isolated EV properties. Using several EV analysis techniques to provide a more detailed insight into EV populations during AEX isolation, we demonstrated that although the composition of CD9/63/81 remained constant for tetraspanin positive EVs, the size distribution and purity changed during elution. Higher salt concentrations eluted larger tetraspanin negative vesicles.

Unveiling the Complex World of Extracellular Vesicles: Novel Characterization Techniques and Manufacturing Considerations

Extracellular vesicles (EVs) function as potent mediators of intercellular communication for many in vivo processes, contributing to both health and disease related conditions. Given their biological origins and diverse functionality from correspondingly unique "cargo" compositions, both endogenous and modified EVs are garnering attention as promising therapeutic modalities and vehicles for targeted therapeutic delivery applications. Their diversity in composition, however, has revealed a significant need for more comprehensive analytical-based characterization methods, and manufacturing processes that are consistent and scalable. In this review, we explore the dynamic landscape of EV research and development efforts, ranging from novel isolation approaches, to their analytical assessment through novel characterization techniques, and to their production by industrial-scale manufacturing process considerations. Expanding the horizon of these topics to EVs for in-human applications, we underscore the need for stringent development and adherence to Good Manufacturing Practice (GMP) guidelines. Wherein, the intricate interplay of raw materials, production in bioreactors, and isolation practices, along with analytical assessments compliant with the Minimal Information for Studies of Extracellular Vesicles (MISEV) guidelines, in conjunction with reference standard materials, collectively pave the way for standardized and consistent GMP production processes.

Size-exclusion chromatography-based extracellular vesicle size subtyping and multiplex membrane protein profiling for differentiating gastrointestinal cancer prognosis

Extracellular vesicles (EVs), as a type of subcellular structure, have been extensively researched for their potential for developing advanced diagnostic technologies for various diseases. However, the biomolecular and biophysical heterogeneity of EVs has restricted their application in clinical settings. In this article, we developed a size-exclusion chromatography-based technique for simultaneous EV size subtyping and protein profiling. By eluting fluorescent aptamer-treated patient plasma through a size-exclusion column, the mixture can be classified into 50 nm aptamer-bound EVs, 100 nm aptamer-bound EVs and free-floating aptamers, which could further enable multiplex EV membrane protein profiling by analyzing the fluorescence intensities of EV-bound aptamers. Using this technique, we successfully identified EV size subtypes for differentiating gastrointestinal cancer prognosis states. Overall, we developed a rapid, user-friendly and low-cost EV size subtyping and protein profiling technique, which holds great potential for identifying crucial EV size subtypes for disease diagnosis in the clinic.

An immuno-magnetophoresis-based microfluidic chip to isolate and detect HER2-Positive cancer-derived exosomes via multiple separation

Exosomes are useful for cancer diagnosis and monitoring. However, clinical samples contain impurities that complicate direct analyses of cancer-derived exosomes. Therefore, a microfluidic chip-based magnetically labeled exosome isolation system (MEIS-chip) was developed as a lab-on-a-chip platform for human epidermal growth factor receptor 2 (HER2)-positive cancer diagnosis and monitoring. Various magnetic nanoclusters (MNCs) were synthesized with different degrees of magnetization, and antibodies were introduced to capture HER2-overexpressing and common exosomes using immunoaffinity. MNC-bonded exosomes were separated into different exits according to their magnetization degrees. The MEIS-chip efficiently separated HER2-overexpressing exosomes from common exosomes that did not contain disease-related information. The simultaneous separation of HER2-and non-HER2-overexpressing exosomes provided a means of analyzing high-purity HER2-overexpressing exosomes while minimizing the contribution of non-target exosomes, reducing misdiagnosis risk. Notably, common exosomes served as a negative control for monitoring real-time changes in HER2 expression. These findings support the application of MEIS-chip for cancer diagnosis and treatment monitoring via effective exosome isolation.

Application of exosome engineering modification in targeted delivery of therapeutic drugs

Cancer is the leading cause of premature death in humans. Scientists have developed several therapeutic drugs for cancer treatment. However, drug delivery faces many problems. First, traditional drugs do not target tumors and are prone to causing significant toxic side effects. Second, suitable drug carriers are essential for improving drug delivery to tumors or circulating cancer cells. Exosomes are natural extracellular vesicles with low immunogenicity and prolonged blood circulation in vivo. These characteristics render exosomes ideal drug carriers. This review highlights the properties of exosomes and mechanisms of exosome biogenesis. It also summarizes the engineering modification methods for enhancing exosome yield, targeting, and drug-loading capacity.

Dental Pulp Stem Cell-Derived Exosomes Regulate Anti-Inflammatory and Osteogenesis in Periodontal Ligament Stem Cells and Promote the Repair of Experimental Periodontitis in Rats

Purpose

Dental pulp stem cell-derived exosomes (DPSC-EXO), which have biological characteristics similar to those of metrocytes, have been found to be closely associated with tissue regeneration. Periodontitis is an immune inflammation and tissue destructive disease caused by plaque, resulting in alveolar bone loss and periodontal epithelial destruction. It is not clear whether DPSC-EXO can be used as an effective therapy for periodontal regeneration. The purpose of this study was not only to verify the effect of DPSC-EXO on reducing periodontitis and promoting periodontal tissue regeneration, but also to reveal the possible mechanism.

Methods

DPSC-EXO was isolated by ultracentrifugation. Then it characterized by transmission electron microscope (TEM), nanoparticle tracking analysis (NTA) and Western Blot. In vitro, periodontal ligament stem cells (PDLSCs) were treated with DPSC-EXO, the abilities of cell proliferation, migration and osteogenic potential were evaluated. Furthermore, we detected the expression of IL-1β, TNF-αand key proteins in the IL-6/JAK2/STAT3 signaling pathway after simulating the inflammatory environment by LPS. In addition, the effect of DPSC-EXO on the polarization phenotype of macrophages was detected. In vivo, the experimental periodontitis in rats was established and treated with DPSC-EXO or PBS. After 4 weeks, the maxillae were collected and detected by micro-CT and histological staining.

Results

DPSC-EXO promoted the proliferation, migration and osteogenesis of PDLSCs in vitro. DPSC-EXO also regulated inflammation by inhibiting the IL-6/JAK2/STAT3 signaling pathway during acute inflammatory stress. In addition, the results showed that DPSC-EXO could polarize macrophages from the M1 phenotype to the M2 phenotype. In vivo, we found that DPSC-EXO could effectively reduce alveolar bone loss and promote the healing of the periodontal epithelium in rats with experimental periodontitis.

Conclusion

DPSC-EXO plays an important role in inhibiting periodontitis and promoting tissue regeneration. This study provides a promising acellular therapy for periodontitis.

Ti3C2 and Ti2C MXene materials for high-performance isolation of extracellular vesicles via coprecipitation

Two-dimensional (2D) materials such as MXenes, are usually well utilized in the field of catalysts and battery due to their good hydrophilicity and diversified surface terminals. However, their potential applications in the treatment of biological samples have not been widely concerned. Extracellular vesicles (EVs) contain unique molecular signatures and could be used as biomarkers for the detection of severe diseases such as cancer, as well as monitoring the therapeutic response. In this work, two kinds of MXene materials (Ti₃C₂ and Ti₂C) were successfully synthesized and employed in the isolation of EVs from the biological samples by taking advantage of the affinity interaction between the titanium (Ti) in MXenes and the phospholipid membrane of EVs. Compared with Ti₂C MXene materials, TiO₂ beads and the other EVs isolation methods, Ti₃C₂ MXene materials exhibited excellent isolation performance via the coprecipitation with EVs due to the abundant unsaturated coordination of Ti²⁺/Ti³⁺, and the dosage of materials was the lowest. Meanwhile, the whole isolation process could be done within 30 min and integrated well with the following analysis of proteins and ribonucleic acids (RNAs), which was also convenient and economic. Furthermore, the Ti₃C₂ MXene materials were used to isolate the EVs from the blood plasma of colorectal cancer (CRC) patients and healthy donors. Proteomics analysis of EVs showed that 67 proteins were up-regulated, in which most of them were closely related to CRC progression. These findings indicate that the MXene material-based EVs isolation method via coprecipitation provides an efficient tool for early diagnosis of diseases.

Secretome-based acellular therapy of bone marrow-derived mesenchymal stem cells in degenerative and immunological disorders: A narrative review

The bone marrow (BM) plays a pivotal role in homeostasis by supporting hematopoiesis and immune cells' activation, maturation, interaction, and deployment. "BMSC-derived secretome" refers to the complete repertoire of secreted molecules, including nucleic acids, chemokines, growth factors, cytokines, and lipids from BM-derived mesenchymal stem cells (BMSCs). BMSC-derived secretomes are the current molecular platform for acellular therapy. Secretomes are highly manipulable and can be synthesised in vast quantities using commercially accessible cell lines in the laboratory. Secretomes are less likely to elicit an immunological response because they contain fewer surface proteins. Moreover, the delivery of BMSC-derived secretomes has been shown in numerous studies to be an effective, cell-free therapy method for alleviating the symptoms of inflammatory and degenerative diseases. As a result, secretome delivery from BMSCs has the same therapeutic effects as BMSCs transplantation but may have fewer adverse effects. Additionally, BMSCs' secretome has therapeutic promise for organoids and parabiosis studies. This review focuses on recent advances in secretome-based cell-free therapy, including its manipulation, isolation, characterisation, and delivery systems. The diverse bioactive molecules of secretomes that successfully treat inflammatory and degenerative diseases of the musculoskeletal, cardiovascular, nervous, respiratory, reproductive, gastrointestinal, and anti-ageing systems were also examined in this review. However, secretome-based therapy has some unfavourable side effects that may restrict its uses. Some of the adverse effects of this modal therapy were briefly mentioned in this review.

Potential Avenues for Exosomal Isolation and Detection Methods to Enhance Small-Cell Lung Cancer Analysis

Around the world, lung cancer has long been the main factor in cancer-related deaths, with small-cell lung cancer (SCLC) being the deadliest form of lung cancer. Cancer cell-derived exosomes and exosomal miRNAs are considered promising biomarkers for diagnosing and prognosis of various diseases, including SCLC. Due to the rapidity of SCLC metastasis, early detection and diagnosis can offer better diagnosis and prognosis and therefore increase the patient's chances of survival. Over the past several years, many methodologies have been developed for analyzing non-SCLC-derived exosomes. However, minimal advances have been made in SCLC-derived exosome analysis methodologies. This Review discusses the epidemiology and prominent biomarkers of SCLC. Followed by a discussion about the effective strategies for isolating and detecting SCLC-derived exosomes and exosomal miRNA, highlighting the critical challenges and limitations of current methodologies. Finally, an overview is provided detailing future perspectives for exosome-based SCLC research.

Preparation of Nanoparticle-Loaded Extracellular Vesicles Using Direct Flow Filtration

Extracellular vesicles (EVs) have shown great potential as cell-free therapeutics and biomimetic nanocarriers for drug delivery. However, the potential of EVs is limited by scalable, reproducible production and in vivo tracking after delivery. Here, we report the preparation of quercetin-iron complex nanoparticle-loaded EVs derived from a breast cancer cell line, MDA-MB-231br, using direct flow filtration. The morphology and size of the nanoparticle-loaded EVs were characterized using transmission electron microscopy and dynamic light scattering. The SDS-PAGE gel electrophoresis of those EVs showed several protein bands in the range of 20-100 kDa. The analysis of EV protein markers by a semi-quantitative antibody array confirmed the presence of several typical EV markers, such as ALIX, TSG101, CD63, and CD81. Our EV yield quantification suggested a significant yield increase in direct flow filtration compared with ultracentrifugation. Subsequently, we compared the cellular uptake behaviors of nanoparticle-loaded EVs with free nanoparticles using MDA-MB-231br cell line. Iron staining studies indicated that free nanoparticles were taken up by cells via endocytosis and localized at a certain area within the cells while uniform iron staining across cells was observed for cells treated with nanoparticle-loaded EVs. Our studies demonstrate the feasibility of using direct flow filtration for the production of nanoparticle-loaded EVs from cancer cells. The cellular uptake studies suggested the possibility of deeper penetration of the nanocarriers because the cancer cells readily took up the quercetin-iron complex nanoparticles, and then released nanoparticle-loaded EVs, which can be further delivered to regional cells.

Extracellular Vesicle-Based Drug Delivery Systems for Head and Neck Squamous Cell Carcinoma: A Systematic Review

It is estimated that there are over 890,000 new cases of head and neck squamous cell carcinoma (HNSCC) worldwide each year, accounting for approximately 5% of all cancer cases. Current treatment options for HNSCC often cause significant side effects and functional impairments, thus there is a challenge to discover more acceptable treatment technologies. Extracellular vesicles (EVs) can be utilized for HNSCC treatment in several ways, for example, for drug delivery, immune modulation, as biomarkers for diagnostics, gene therapy, or tumor microenvironment modulation. This systematic review summarizes new knowledge regarding these options. Articles published up to 11 December 2022, were identified by searching the electronic databases PubMed/MEDLINE, Scopus, Web of Science, and Cochrane. Only full-text original research papers written in English were considered eligible for analysis. The quality of studies was assessed using the Office of Health Assessment and Translation (OHAT) Risk of Bias Rating Tool for Human and Animal Studies, modified for the needs of this review. Of 436 identified records, 18 were eligible and included. It is important to note that the use of EVs as a treatment for HNSCC is still in the early stages of research, so we summarized information on challenges such as EV isolation, purification, and standardization of EV-based therapies in HNSCC.

Urinary Exosomes: A Promising Biomarker for Disease Diagnosis

Exosomes are nanoscale vesicles derived from endocytosis, formed by fusion of multivesicular bodies with membranes and secreted into the extracellular matrix or body fluids. Many studies have shown that exosomes can be present in a variety of biological fluids, such as plasma, urine, saliva, amniotic fluid, ascites, and sweat, and most types of cells can secrete exosomes. Exosomes play an important role in many aspects of human development, including immunity, cardiovascular diseases, neurodegenerative diseases, and neoplasia. Urine can be an alternative to blood or tissue samples as a potential source of disease biomarkers because of its simple, noninvasive, sufficient, and stable characteristics. Therefore, urinary exosomes have valuable potential for early screening, monitoring disease progression, prognosis, and treatment. The method for isolating urinary exosomes has been perfected, and exosome proteomics is widely used. Therefore, we review the potential use of urinary exosomes for disease diagnosis and summarize the related literature.

Emerging role of mesenchymal stem/stromal cells (MSCs) and MSCs-derived exosomes in bone- and joint-associated musculoskeletal disorders: a new frontier

Exosomes are membranous vesicles with a 30 to 150 nm diameter secreted by mesenchymal stem/stromal cells (MSCs) and other cells, such as immune cells and cancer cells. Exosomes convey proteins, bioactive lipids, and genetic components to recipient cells, such as microRNAs (miRNAs). Consequently, they have been implicated in regulating intercellular communication mediators under physiological and pathological circumstances. Exosomes therapy as a cell-free approach bypasses many concerns regarding the therapeutic application of stem/stromal cells, including undesirable proliferation, heterogeneity, and immunogenic effects. Indeed, exosomes have become a promising strategy to treat human diseases, particularly bone- and joint-associated musculoskeletal disorders, because of their characteristics, such as potentiated stability in circulation, biocompatibility, low immunogenicity, and toxicity. In this light, a diversity of studies have indicated that inhibiting inflammation, inducing angiogenesis, provoking osteoblast and chondrocyte proliferation and migration, and negative regulation of matrix-degrading enzymes result in bone and cartilage recovery upon administration of MSCs-derived exosomes. Notwithstanding, insufficient quantity of isolated exosomes, lack of reliable potency test, and exosomes heterogeneity hurdle their application in clinics. Herein, we will deliver an outline respecting the advantages of MSCs-derived exosomes-based therapy in common bone- and joint-associated musculoskeletal disorders. Moreover, we will have a glimpse the underlying mechanism behind the MSCs-elicited therapeutic merits in these conditions.

Magnetic enrichment of immuno-specific extracellular vesicles for mass spectrometry using biofilm-derived iron oxide nanowires

Immuno-specific enrichment of extracellular vesicles (EVs) can provide important information into cellular pathways underpinning various pathologies and for non-invasive diagnostics, including mass spectrometry-based analyses. Herein, we report an optimised protocol for immuno-magnetic enrichment of specific EV subtypes and their subsequent processing with liquid chromatography-tandem mass spectrometry (LC-MS/MS). Specifically, we conjugated placental alkaline phosphatase (PLAP) antibodies to magnetic iron oxide nanowires (NWs) derived from bacterial biofilms and demonstrated the utility of this approach by enriching placenta-specific EVs (containing PLAP) from cell culture media. We demonstrate efficient PLAP+ve EV enrichment for both NW-PLAP and Dynabeads™-PLAP, with high PLAP protein recovery (83.7 ± 8.9% and 83.2 ± 5.9%, respectively), high particle-to-protein ratio (7.5 ± 0.7 × 10⁹ and 7.1 ± 1.2 × 10⁹, respectively), and low non-specific binding of non-target EVs (7 ± 3.2% and 5.4 ± 2.2%, respectively). Furthermore, our optimized EV enrichment and processing approach identified 2518 and 2545 protein groups with LC-MS/MS for NW-PLAP and Dynabead™-PLAP, respectively, with excellent reproducibility (Pearson correlation 0.986 and 0.988). These findings demonstrate that naturally occurring iron oxide NWs have comparable performance to current gold standard immune-magnetic beads. The optimized immuno-specific EV enrichment for LC-MS/MS method provides a low-cost and highly-scalable yet efficient, high-throughput approach for quality EV proteomic studies.

Analyzing bronchoalveolar fluid derived small extracellular vesicles using single-vesicle SERS for non-small cell lung cancer detection

An emerging body of research by biologists and clinicians has demonstrated the clinical application of small extracellular vesicles (sEVs, also commonly referred to as exosomes) as biomarkers for cancer detections. sEVs isolated from various body fluids such as blood, saliva, urine, and cerebrospinal fluid have been used for biomarker discoveries with highly encouraging outcomes. Among the biomarkers discovered are those responsible for multiple cancer types and immune responses. These biomarkers are recapitulated from the tumor microenvironments. Yet, despite numerous discussions of sEVs in scientific literature, sEV-based biomarkers have so far played only a minor role for cancer diagnostics in the clinical setting, notably less so than other techniques such as imaging and biopsy. In this paper, we report the results of a pilot study (n = 10 from each of the patient and the control group) using bronchoalveolar lavage fluid to determine the presence of sEVs related to non-small cell lung cancer in twenty clinical samples examined using surface enhanced Raman spectroscopy (SERS).

The exosome: a review of current therapeutic roles and capabilities in human reproduction

Exosomes are nano-vesicles (30-150 nm) which may be useful as therapeutic delivery vehicles and as diagnostic biomarkers. Exosomes are produced naturally within the human body and therefore are not prone to immunogenicity effects which would otherwise destroy unelicited foreign bodies. Clinically, they have been regarded as ideal candidates for applications relating to biomarker developments for the early detection of different diseases. Furthermore, exosomes may be of interest as potential drug delivery vehicles, which may improve factors such as bioavailability of loaded molecular cargo, side effect profiles, off-target effects, and pharmacokinetics of drug molecules. In this review, the therapeutic potential of exosomes and their use as clinical biomarkers for early diagnostics will be explored, alongside exosomes as therapeutic delivery vehicles. This review will evaluate techniques for cargo loading, and the capacity of loaded exosomes to improve various reproductive disease states. It becomes important, therefore, to consider factors such as loading efficiency, loading methods, cell viability, exosomal sources, exosome isolation, and the potential therapeutic benefits of exosomes. Issues related to targeted drug delivery will also be discussed. Finally, the variety of therapeutic cargo and the application of appropriate loading methods is explored, in the context of establishing clinical utility. Exosomes have more recently been widely accpeted as potential tools for disease diagnostics and the targeted delivery of certain therapeutic molecules-and in due time exosomes will be utilised more commonly within the clinical setting. Specifically, exosomal biomarkers can be identified and related to various detrimental conditions which occur during pregnancy. Considering, this review will explore the potential future of exosomes as both diagnostic tools and therapeutic delivery vehicles to treat related conditions, including the challenges which exist towards incorporating exosomes within the clinical environment to benefit patients.

Magnetic Nanoparticles for Protein Separation and Purification

Proteins are essential for various functions such as brain activity and muscle contraction in humans. Even though food is a source of proteins, the bioavailability of proteins in most foods is usually limited due to matrix interaction with other biomolecules. Thus, it is essential to extract these proteins and provide them as a nutraceutical supplement to maintain protein levels and avoid protein deficiency. Hence, protein purification and extraction from natural sources are highly significant in biomedical applications. Chromatography, crude mechanical disruption, use of extractive chemicals, and electrophoresis are some of the methods applied to isolate specific proteins. Even though these methods possess several advantages, they are unable to extract specific proteins with high purity. A suitable alternative is the use of nanoparticles, which can be beneficial in protein purification and extraction. Notably, magnetic iron and iron-based nanoparticles have been employed in protein extraction processes and can be reused via demagnetization due to their magnetic property, smaller size, morphology, high surface-to-volume ratio, and surface charge-mediated property. This chapter is a summary of various magnetic nanoparticles (MNPs) that can be used for the biomolecular separation of proteins.

Applications of Exosomes in Diagnosing Muscle Invasive Bladder Cancer

Muscle Invasive Bladder Cancer (MIBC) is a subset of bladder cancer with a significant risk for metastases and death. It accounts for nearly 25% of bladder cancer diagnoses. A diagnostic work-up for MIBC is inclusive of urologic evaluation, radiographic imaging with a CT scan, urinalysis, and cystoscopy. These evaluations, especially cystoscopy, are invasive and carry the risk of secondary health concerns. Non-invasive diagnostics such as urine cytology are an attractive alternative currently being investigated to mitigate the requirement for cystoscopy. A pitfall in urine cytology is the lack of available options with high reliability, specificity, and sensitivity to malignant bladder cells. Exosomes are a novel biomarker source which could resolve some of the concerns with urine cytology, due to the high specificity as the surrogates of tumor cells. This review serves to define muscle invasive bladder cancer, current urine cytology methods, the role of exosomes in MIBC, and exosomes application as a diagnostic tool in MIBC. Urinary exosomes as the specific populations of extracellular vesicles could provide additional biomarkers with specificity and sensitivity to bladder malignancies, which are a consistent source of cellular information to direct clinicians for developing treatment strategies. Given its strong presence and differentiation ability between normal and cancerous cells, exosome-based urine cytology is highly promising in providing a perspective of a patient’s bladder cancer.

Extracellular Vesicles and Membrane Protrusions in Developmental Signaling

During embryonic development, cells communicate with each other to determine cell fate, guide migration, and shape morphogenesis. While the relevant secreted factors and their downstream target genes have been characterized extensively, how these signals travel between embryonic cells is still emerging. Evidence is accumulating that extracellular vesicles (EVs), which are well defined in cell culture and cancer, offer a crucial means of communication in embryos. Moreover, the release and/or reception of EVs is often facilitated by fine cellular protrusions, which have a history of study in development. However, due in part to the complexities of identifying fragile nanometer-scale extracellular structures within the three-dimensional embryonic environment, the nomenclature of developmental EVs and protrusions can be ambiguous, confounding progress. In this review, we provide a robust guide to categorizing these structures in order to enable comparisons between developmental systems and stages. Then, we discuss existing evidence supporting a role for EVs and fine cellular protrusions throughout development.

Magnetic guanidyl-functionalized covalent organic framework composite: a platform for specific capture and isolation of phosphopeptides and exosomes

A guanidine-functionalized (GF) covalent organic framework (COF) nanocomposite has been developed by a post-synthetic approach for specific capture and separation of phosphopeptides and exosomes. The abundant binding sites on COF can immobilize a large number of gold nanoparticles (AuNPs), which can be used to react with amino groups to graft polyethyleneimine (PEI). Finally, Fe₃O₄@COF@Au@PEI-GF is obtained through the reaction of PEI and guanidyl group for phosphopeptides and exosomes detection. This composite shows a low detection limit (0.02 fmol), size exclusion effect (β-casein digests:Albumin from bovine serum protein = 1:10,000), good reusability (10 cycles), and high selectivity (β-casein digests:Albumin from bovine serum digests = 1:10,000). For complex biological sample, 4 phosphopeptides can be successfully identified from human serum. Furthermore, for the first time, we used guanidyl-functionalized probe to capture exosomes in human serum, providing a new method for enriching exosomes. The above experiments showed that Fe₃O₄@COF@Au@PEI-GF not only effectively enrich phosphopeptides and remove macromolecular proteins, but also successfully separate and capture exosomes. This demonstrates the great potential of this composite for the specific enrichment of phosphopeptides and isolation of exosomes.

Exosome derived from stem cell: A promising therapeutics for wound healing

A wound occurs when the epidermis and dermis of the skin are damaged internally and externally. The traditional wound healing method is unsatisfactory, which will prolong the treatment time and increase the treatment cost, which brings economic and psychological burdens to patients. Therefore, there is an urgent need for a new method to accelerate wound healing. As a cell-free therapy, exosome derived from stem cell (EdSC) offers new possibilities for wound healing. EdSC is the smallest extracellular vesicle secreted by stem cells with diameters of 30–150 nm and a lipid bilayer structure. Previous studies have found that EdSC can participate in and promote almost all stages of wound healing, including regulating inflammatory cells; improving activation of fibroblasts, keratinocytes, and endothelial cells; and adjusting the ratio of collagen Ⅰ and Ⅲ. We reviewed the relevant knowledge of wounds; summarized the biogenesis, isolation, and identification of exosomes; and clarified the pharmacological role of exosomes in promoting wound healing. This review provides knowledge support for the pharmacological study of exosomes.

Isolation of circulating exosomes and identification of exosomal PD-L1 for predicting immunotherapy response

Exosomes, a subgroup of extracellular vesicles secreted by multiple cells, have great potential as cancer biomarkers in clinical applications. However, enrichment and detection of exosomes from complex media remain a huge challenge due to their small size. Herein, we used iodixanol density gradient centrifugation for the isolation and purification of exosomes and label-free detection of exosomal PD-L1 using a biochip based on surface plasmon resonance (SPR-Exo_PD-L1). The obtained exosomes are lipid-bilayer vesicles and the classical exosome markers CD9, CD63 and CD81 are highly enriched. Besides, PD-L1 is specifically expressed on exosomes instead of non-vesicular components or large extracellular vesicles. Compared with enzyme-linked immunosorbent assays, the SPR-Exo_PD-L1 assay could better distinguish exosomes derived from melanoma cells with different levels of PD-L1. Accurate measurement of exosomal PD-L1 could provide critical clinical information for cancer diagnosis and personalized immunotherapy of cancer.

Advances of exosomes in periodontitis treatment

Periodontitis is an inflammatory disease initiated by dysbiosis of the local microbial community. Periodontitis can result in destruction of tooth-supporting tissue; however, overactivation of the host immune response is the main reason for alveolar bone loss. Periodontal tissue cells, immune cells, and even further activated osteoclasts and neutrophils play pro-inflammatory or anti-inflammatory roles. Traditional therapies for periodontitis are effective in reducing the microbial quantities and improving the clinical symptoms of periodontitis. However, these methods are non-selective, and it is still challenging to achieve an ideal treatment effect in clinics using the currently available treatments and approaches. Exosomes have shown promising potential in various preclinical and clinical studies, including in the diagnosis and treatment of periodontitis. Exos can be secreted by almost all types of cells, containing specific substances of cells: RNA, free fatty acids, proteins, surface receptors and cytokines. Exos act as local and systemic intercellular communication medium, play significant roles in various biological functions, and regulate physiological and pathological processes in numerous diseases. Exos-based periodontitis diagnosis and treatment strategies have been reported to obtain the potential to overcome the drawbacks of traditional therapies. This review focuses on the accumulating evidence from the last 5 years, indicating the therapeutic potential of the Exos in preclinical and clinical studies of periodontitis. Recent advances on Exos-based periodontitis diagnosis and treatment strategies, existing challenges, and prospect are summarized as guidance to improve the effectiveness of Exos on periodontitis in clinics.

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.

Extracellular Vesicle-Based Multianalyte Liquid Biopsy as a Diagnostic for Cancer

Liquid biopsy is the analysis of materials shed by tumors into circulation, such as circulating tumor cells, nucleic acids, and extracellular vesicles (EVs), for the diagnosis and management of cancer. These assays have rapidly evolved with recent FDA approvals of single biomarkers in patients with advanced metastatic disease. However, they have lacked sensitivity or specificity as a diagnostic in early-stage cancer, primarily due to low concentrations in circulating plasma. EVs, membrane-enclosed nanoscale vesicles shed by tumor and other cells into circulation, are a promising liquid biopsy analyte owing to their protein and nucleic acid cargoes carried from their mother cells, their surface proteins specific to their cells of origin, and their higher concentrations over other noninvasive biomarkers across disease stages. Recently, the combination of EVs with non-EV biomarkers has driven improvements in sensitivity and accuracy; this has been fueled by the use of machine learning (ML) to algorithmically identify and combine multiple biomarkers into a composite biomarker for clinical prediction. This review presents an analysis of EV isolation methods, surveys approaches for and issues with using ML in multianalyte EV datasets, and describes best practices for bringing multianalyte liquid biopsy to clinical implementation. Expected final online publication date for the Annual Review of Biomedical Data Science, Volume 5 is August 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Harnessing the Therapeutic Potential of Extracellular Vesicles for Biomedical Applications Using Multifunctional Magnetic Nanomaterials

Extracellular vesicles (e.g., exosomes) carrying various biomolecules (e.g., proteins, lipids, and nucleic acids) have rapidly emerged as promising platforms for many biomedical applications. Despite their enormous potential, their heterogeneity in surfaces and sizes, the high complexity of cargo biomolecules, and the inefficient uptake by recipient cells remain critical barriers for their theranostic applications. To address these critical issues, multifunctional nanomaterials, such as magnetic nanomaterials, with their tunable physical, chemical, and biological properties, may play crucial roles in next-generation extracellular vesicles (EV)-based disease diagnosis, drug delivery, tissue engineering, and regenerative medicine. As such, one aims to provide cutting-edge knowledge pertaining to magnetic nanomaterials-facilitated isolation, detection, and delivery of extracellular vesicles and their associated biomolecules. By engaging the fields of extracellular vesicles and magnetic nanomaterials, it is envisioned that their properties can be effectively combined for optimal outcomes in biomedical applications.

Overview of extracellular vesicle characterization techniques and introduction to combined reflectance and fluorescence confocal microscopy to distinguish extracellular vesicle subpopulations

Extracellular vesicles (EVs) are nanoparticles (30 to 1000 nm in diameter) surrounded by a lipid-bilayer which carry bioactive molecules between local and distal cells and participate in intercellular communication. Because of their small size and heterogenous nature they are challenging to characterize. Here, we discuss commonly used techniques that have been employed to yield information about EV size, concentration, mechanical properties, and protein content. These include dynamic light scattering, nanoparticle tracking analysis, flow cytometry, transmission electron microscopy, atomic force microscopy, western blotting, and optical methods including super-resolution microscopy. We also introduce an innovative technique for EV characterization which involves immobilizing EVs on a microscope slide before staining them with antibodies targeting EV proteins, then using the reflectance mode on a confocal microscope to locate the EV plane. By then switching to the microscope's fluorescence mode, immunostained EVs bearing specific proteins can be identified and the heterogeneity of an EV preparation can be determined. This approach does not require specialist equipment beyond the confocal microscopes that are available in many cell biology laboratories, and because of this, it could become a complementary approach alongside the aforementioned techniques to identify molecular heterogeneity in an EV preparation before subsequent analysis requiring specialist apparatus.

Efficient exosome subpopulation isolation and proteomic profiling using a Sub-ExoProfile chip towards cancer diagnosis and treatment

Deconstruction of the heterogeneity of surface marker-dependent exosome subpopulations by the Sub-ExoProfile chip.

Improving Isolation of Extracellular Vesicles by Utilizing Nanomaterials

Extracellular vesicles (EVs) as the new form of cellular communication have been demonstrated their potential use for disease diagnosis, prognosis and treatment. EVs are vesicles with a lipid bilayer and are present in various biofluids, such as blood, saliva and urine. Therefore, EVs have emerged as one of the most appealing sources for the discovery of clinical biomarkers. However, isolation of the target EVs from different biofluids is required for the use of EVs as diagnostic and therapeutic entities in clinical settings. Owing to their unique properties and versatile functionalities, nanomaterials have been widely investigated for EV isolation with the aim to provide rapid, simple, and efficient EV enrichment. Herein, this review presents the progress of nanomaterial-based isolations for EVs over the past five years (from 2017 to 2021) and discusses the use of nanomaterials for EV isolations based on the underlying mechanism in order to offer insights into the design of nanomaterials for EV isolations.

Fast quantification of extracellular vesicles levels in early breast cancer patients by Single Molecule Detection Array (SiMoA)

PURPOSE

Preliminary reports suggest that extracellular vesicles (EVs) might be a promising biomarker for breast cancer (BC). However, the quantification of plasmatic levels of EVs is a complex task. To overcome these limitations, we developed a new, fast, and easy to use assay for the quantification of EVs directly in plasma based on the use of Single-Molecule Array (SiMoA).

METHODS

By using SiMoA to identify CD9+/CD63+ EVs, we analyzed plasma samples of 181 subjects (95 BC and 86 healthy controls, HC). A calibration curve, made of a serial dilution of lyophilized standards from human plasma, was used in each run to ensure the obtainment of quantitative results from the assay. In a subgroup of patients, EVs concentrations were estimated in plasma before and after 30 days from cancer surgery. Additional information on the size of EVs were also acquired using a Nanosight system to obtain a clearer understanding of the mechanism underlying the releases of EVs associated with the presence of cancer.

RESULTS

The measured levels of EVs resulted significantly higher in BC patients (median values 1179.1 ng/µl vs 613.0 ng/µl, p < 0.0001). ROC curve was used to define the optimal cut-off level of the test at 1034.5 ng/µl with an AUC of 0.75 [95% CI 0.68-0.82]. EVs plasmatic concentrations significantly decreased after cancer surgery compared to baseline values (p = 0.014). No correlation was found between EVs concentration and clinical features of BC.

CONCLUSION

SiMoA assay allows plasmatic EVs levels detection directly without any prior processing. EVs levels are significantly higher in BC patients and significantly decreases after cancer surgery.

Nanoparticle-Enabled Multiplexed Electrochemical Immunoassay for Detection of Surface Proteins on Extracellular Vesicles

Extracellular vesicles (EVs) are lipid bilayer particles secreted from various cells. EVs carry molecular information of parent cells and hold considerable promise for early disease diagnostics. This paper describes a general strategy for multiplexed immunosensing of EV surface proteins, focusing on surface markers CD63, CD81, nephrin, and podocin to prove the concept. This sensing strategy entailed functionalizing gold nanoparticles (AuNPs) with two types of antibodies and then tagging with metal ions, either Pb2+ or Cu2+. The metal ions served as redox reporters, generating unique redox peaks at -0.23 and 0.28 V (vs Ag/AgCl) during electrochemical oxidation of Pb2+ and Cu2+, respectively. Capture of EVs on the working electrode, followed by labeling with immunoprobes and square wave voltammetry, produced redox currents proportional to concentrations of EVs and levels of expression of EV surface markers. Importantly, metal-ion tagging of immunoprobes enabled detection of two EV surface markers simultaneously from the same electrode. We demonstrated dual detection of either CD63/CD81 or podocin/nephrin surface markers from urinary EVs. The NP-enabled immunoassay had a sensitivity of 2.46 × 105 particles/mL (or 40.3 pg/mL) for CD63- and 5.80 × 105 particles/mL (or 47.7 pg/mL) for CD81-expressing EVs and a linear range of four orders of magnitude. The limit of detection for podocin and nephrin was 3.1 and 3.8 pg/mL, respectively. In the future, the capacity for multiplexing may be increased by extending the repertoire of metal ions used for redox tagging of AuNPs.

A Portable Device for Simple Exosome Separation from Biological Samples

Exosomes are membrane-bound nanovesicles secreted by most types of cells, which contain a series of biologically important molecules, such as miRNAs, proteins, and lipids, etc. Emerging evidence show that exosomes can affect the physiological status of cells and are involved in various pathological processes. However, due to their small size and density close to body fluids, it is challenging to separate exosomes from a small volume of biological samples in a simple manner. Herein, we propose a new strategy for isolating circulating exosomes from biological samples in a portable device. This method synergistically integrates chitosan electrostatic-adsorption, scaffold substrates, and shuttle flow to enable the highly effective capture of circulating exosomes with a recovery rate of over 80% within 20 min, which is much better than the performance of traditional ultracentrifugation (5–25%, 3 h). Besides, the isolated exosomes from samples could be lysed in situ and further subjected to RNA concentration detection and protein analysis. In particular, all the necessary procedures for exosome separation could be integrated into a single device without the need for bulky equipment. This established device is portable and easy to operate, which provides a promising platform for the study of exosome biology and clinical diagnosis.

Exosomal Proteins and miRNAs as Mediators of Amyotrophic Lateral Sclerosis

Recent advances in the neurobiology and neurogenerative diseases have attracted growing interest in exosomes and their ability to carry and propagate active biomolecules as a means to reprogram recipient cells. Alterations in exosomal protein content and nucleic acid profiles found in human biological fluids have been correlated with various diseases including amyotrophic lateral sclerosis (ALS). In ALS pathogenesis, these lipid-bound nanoscale vesicles have emerged as valuable candidates for diagnostic biomarkers. Moreover, their capacity to spread misfolded proteins and functional non-coding RNAs to interconnected neuronal cells make them putative mediators for the progressive motor degeneration found remarkably apparent in ALS. This review outlines current knowledge concerning the biogenesis, heterogeneity, and function of exosomes in the brain as well as a comprehensive probe of currently available literature on ALS-related exosomal proteins and microRNAs. Lastly, with the rapid development of employing nanoparticles for drug delivery, we explore the therapeutic potentials of exosomes as well as underlying limitations in current isolation and detection methodologies.

Microsphere mediated exosome isolation and ultra-sensitive detection on a dielectrophoresis integrated microfluidic device

Tumor-derived exosomes have been recognized as potential biomarkers for cancer diagnosis because they are actively involved in cancer progression and metastasis. However, progress in practical exosome analysis is still slow due to the limitation in exosome isolation and detection. The development of microfluidic devices has provided a promising analytical platform compared with traditional methods. In this study, we develop an exosome isolation and detection method based on a microfluidic device (ExoDEP-chip), which realized microsphere mediated dielectrophoretic isolation and immunoaffinity detection. Exosomes were firstly isolated by binding to antibodies pre-immobilized on the polystyrene (PS) microsphere surface and were further detected using fluorescently labeled antibodies by fluorescence microscopy. Single microspheres were then trapped into single microwells under the DEP force in the ExoDEP-chip. A wide range from 1.4 × 10³ to 1.4 × 10⁸ exosomes per mL with a detection limit of 193 exosomes per mL was obtained. Through monitoring five proteins (CD81, CEA, EpCAM, CD147, and AFP) of exosomes from three different cell lines (A549, HEK293, and HepG2), a significant difference in marker expression levels was observed in different cell lines. Therefore, this method has good prospects in exosome-based tumor marker detection and cancer diagnosis.

Ultrasensitive Exosome Detection by Modularized SERS Labeling for Postoperative Recurrence Surveillance

Exosome-based liquid biopsy holds great potential in monitoring tumor progression. Current exosome detection biosensors rely on signal amplification strategies to improve sensitivity; however, these strategies pay little attention to manipulating the number of signal reporters, limiting the rational optimization of the biosensors. Here, we have developed a modularized surface-enhanced Raman spectroscopy (SERS) labeling strategy, where each Raman reporter is coupled with lysine as a signal-lysine module, and thus the number of Raman reporters can be precisely controlled by the modularized solid-phase peptide synthesis. Using this strategy, we screened out an optimum Raman biosensor for ultrasensitive exosome detection, with the limit of detection of 2.4 particles per microliter. This biosensor enables a successful detection of the tumor with an average diameter of approximately 3.55 mm, and thus enables successful surveillance of the postoperative tumor recurrence in mice models and distinguishing cancer patients from healthy subjects. Our work provides a de novo strategy to precisely amplify signals toward a myriad of biosensor-related medical applications.