Structural-mechanical characterization of nanoparticle exosomes in human saliva, using correlative AFM, FESEM, and force spectroscopy

Mechanical properties of blood exosomes and lipoproteins after the rat whole blood irradiation with X-rays in vitro explored by atomic force microscopy

Blood is a two-component system with two levels of hierarchy: the macrosystem of blood formed elements and the dispersed system of blood nanoparticles. Biological nanoparticles are the key participants in communication between the irradiated and non-irradiated cells and inducers of the non-targeted effects of ionizing radiation. The work aimed at studying by atomic force microscopy the structural, mechanical, and electrical properties of exosomes and lipoproteins (LDL/VLDL) isolated from rat blood after its exposure to X-rays in vitro.

MATERIALS AND METHODS

The whole blood of Wistar rats fed with a high-fat diet was irradiated with X-rays (1 and 100 Gy) in vitro. The structural and mechanical properties (the elastic modulus and nonspecific adhesion force) of exosome and lipoprotein isolates from the blood by ultracentrifugation method were studied using Bruker Bioscope Resolve atomic force microscope in PF QNM mode, their electric properties (the zeta-potential) was measured by electrophoretic mobility.

RESULTS

Lipoproteins isolated from non-irradiated blood were softer (Me(LQ; UQ): 7.8(4.9;12.1) MPa) compared to blood nanoparticles of its exosome fraction (34.8(22.6;44.9) MPa) containing both exosomes and non-membrane nanoparticles. X-ray blood irradiation with a dose of 1 Gy significantly weakened the elastic properties of lipoproteins. Exposure of the blood to 100 Gy X-rays made lipoproteins stiffer and their nonspecific adhesive properties stronger. The radiation effects on the mechanical parameters of exosomes and non-membrane nanoparticles in exosome fractions differed. The significant radiation-induced change in electric properties of the studied nanoparticles was detected only for lipoproteins in the blood irradiated with 1 Gy X-rays. The low-dose radiation-induced changes in zeta-potential and increase in lipoprotein size with the appearance of a soft thick surface layer indicate the formation of the modified lipoproteins covered with a corona from macromolecules of irradiated blood.

CONCLUSION

Our data obtained using the nanomechanical mapping mode of AFM are the first evidence of the significant radiation-induced changes in the structural and mechanical properties of the dispersed system of blood nanoparticles after the X-ray irradiation of the blood.

Unveiling the potential: Extracellular vesicles from plant cell suspension cultures as a promising source

Extracellular vesicles are secreted by all eukaryotic cells and they have an important role in intercellular signaling. Plant extracellular vesicles (PEVs) are a novel area of research that has gained attention due to their potential implications in biomolecule transport and therapeutic applications. PEVs are lipid bilayer-enclosed structures that contain a diverse cargo of biomolecules such as proteins and lipids. Moreover, it is known that PEVs have a noticeable therapeutic potential for various conditions such as inflammation and oxidative stress. However, there are critical problems such as removing the endosomes and plant-derived biomolecules that decrease the standardization and therapeutic efficacy of PEVs. In our study, the aim was to characterize plant cell suspension-derived extracellular vesicles (PCSEVs) obtained from two different plant cell suspension cultures: Stevia rebaudiana and Vaccaria hispanica. These vesicles were isolated using ultrafiltration and characterized with nanoparticle tracking analysis (NTA) and atomic force microscopy (AFM). The molecular composition of PCSEVs was profiled and the cellular uptake assay was performed. Our results demonstrated that PCSEVs have a spherical shape, less than 200 nm. In the fatty acid analysis, the primary components in PCSEVs were palmitic acid, linoleic acid, and cis-vaccenic acid. The protein content of Stevia rebaudiana-derived EVs (SDEVs) was largely associated with proteins involved in extracellular structures and functions. Conversely, Vaccaria hispanica-derived EVs (HDEVs) displayed a higher presence of cytosolic proteins. These findings contribute to the understanding of PCSEVs and open up potential avenues in extracellular vesicle research, pointing to promising prospects for future innovations in various fields.

Nanoplasmonic sensors for extracellular vesicles and bacterial membrane vesicles

Extracellular vesicles (EVs) are promising tools for the early diagnosis of diseases, and bacterial membrane vesicles (MVs) are especially important in health and environment monitoring. However, detecting EVs or bacterial MVs presents significant challenges for the clinical translation of EV-based diagnostics. In this Review, we provide a comprehensive discussion on the basics of nanoplasmonic sensing and emphasize recent developments in nanoplasmonics-based optical sensors to effectively identify EVs or bacterial MVs. We explore various nanoplasmonic sensors tailored for EV or bacterial MV detection, emphasizing the application of localized surface plasmon resonance through gold nanoparticles and their multimers. Additionally, we highlight advanced EV detection techniques based on surface plasmon polaritons using plasmonic thin film and nanopatterned structures. Furthermore, we evaluate the improved detection capability of surface-enhanced Raman spectroscopy in identifying and classifying these vesicles, aided by plasmonic nanostructures. Nanoplasmonic sensing techniques have remarkable precision and sensitivity, making them a potential tool for accurate EV detection in clinical applications, facilitating point-of-care molecular diagnostics. Finally, we summarize the challenges associated with nanoplasmonic EV or bacterial MV sensors and offer insights into potential future directions for this evolving field.

Canine Mesenchymal Stromal Cell Exosomes: State-of-the-Art Characterization, Functional Analysis and Applications in Various Diseases

Canine mesenchymal stromal cells (MSCs) possess the capacity to differentiate into a variety of cell types and secrete a wide range of bioactive molecules in the form of soluble and membrane-bound exosomes. Extracellular vesicles/exosomes are nano-sized vesicles that carry proteins, lipids, and nucleic acids and can modulate recipient cell response in various ways. The process of exosome formation is a physiological interaction between cells. With a significant increase in basic research over the last two decades, there has been a tremendous expansion in research in MSC exosomes and their potential applications in canine disease models. The characterization of exosomes has demonstrated considerable variations in terms of source, culture conditions of MSCs, and the inclusion of fetal bovine serum or platelet lysate in the cell cultures. Furthermore, the amalgamation of exosomes with various nano-materials has become a novel approach to the fabrication of nano-exosomes. The fabrication of exosomes necessitates the elimination of extrinsic proteins, thus enhancing their potential therapeutic uses in a variety of disease models, including spinal cord injury, osteoarthritis, and inflammatory bowel disease. This review summarizes current knowledge on the characteristics, biological functions, and clinical relevance of canine MSC exosomes and their potential use in human and canine research. As discussed, exosomes have the ability to control lethal vertebrate diseases by administration directly at the injury site or through specific drug delivery mechanisms.

Proteomic Analysis of Salivary Extracellular Vesicles from COVID-19 Patients Reveals a Specific Anti-COVID-19 Response Protein Signature

Despite the understanding of the coronavirus disease-19 (COVID-19), the role of salivary extracellular vesicles (sEVs) in COVID-19 remains unclear. Exploring the proteomic cargo of sEVs could prove valuable for diagnostic and prognostic purposes in assessing COVID-19. The proteomic cargo of sEVs from COVID-19(+) subjects and their healthy close contacts (HCC) was explored. sEVs were isolated by ultracentrifugation from unstimulated saliva samples, and subsequently characterized through nanoparticle tracking, transmission electron microscopy, and Western blot analyses. The proteomic cargo of sEVs was processed by LC-MS/MS. sEVs were morphologically compatible with EVs, with the presence of Syntenin-1 and CD81 EV markers. The sEV pellet showed 1417 proteins: 1288 in COVID-19(+) cases and 1382 in HCC. In total, 124 proteins were differentially expressed in sEVs from COVID-19(+) subjects. "Coronavirus-disease response", "complement and coagulation cascades", and "PMN extracellular trap formation" were the most enriched KEGG pathways in COVID-19(+) cases. The most represented biological processes were "Hemoglobin and haptoglobin binding" and "oxygen carrier activity", and the best-denoted molecular functions were "regulated exocytosis and secretion" and "leucocyte and PMN mediated immunity". sEV proteomic cargo in COVID-19(+) suggests activity related to immune response processes, oxygen transport, and antioxidant mechanisms. In contrast, in HCC, sEV signature profiles are mainly associated with epithelial homeostasis.

Targeted exosome-based nanoplatform for new-generation therapeutic strategies

Exosomes, typically 30-150 nm in size, are lipid-bilayered small-membrane vesicles originating in endosomes. Exosome biogenesis is regulated by the coordination of various mechanisms whereby different cargoes (e.g. proteins, nucleic acids, and lipids) are sorted into exosomes. These components endow exosomes with bioregulatory functions related to signal transmission and intercellular communication. Exosomes exhibit substantial potential as drug-delivery nanoplatforms owing to their excellent biocompatibility and low immunogenicity. Proteins, miRNA, siRNA, mRNA, and drugs have been successfully loaded into exosomes, and these exosome-based delivery systems show satisfactory therapeutic effects in different disease models. To enable targeted drug delivery, genetic engineering and chemical modification of the lipid bilayer of exosomes are performed. Stimuli-responsive delivery nanoplatforms designed with appropriate modifications based on various stimuli allow precise control of on-demand drug delivery and can be utilized in clinical treatment. In this review, we summarize the general properties, isolation methods, characterization, biological functions, and the potential role of exosomes in therapeutic delivery systems. Moreover, the effective combination of the intrinsic advantages of exosomes and advanced bioengineering, materials science, and clinical translational technologies are required to accelerate the development of exosome-based delivery nanoplatforms.

Impact of Choline Hydroxide-Supported Magnetic Nanoparticles on Peroxidase Activity and Conformational Stability of Cytochrome c

Nanotechnology has advanced significantly; however, little is known about the potential implications on human health-related issues, particularly blood carrying enzymes. Ionic liquids are also well-recognized for maintaining the structure and activity of enzymes. In this regard, we delineate a facile synthetic approach of preparation of Fe3O4 nanoparticles (NPs) as well as choline hydroxide [CH][OH] ionic liquid (IL)-supported Fe3O4 NPs (Fe3O4-CHOH). This approach of combining magnetic nanoparticles (MNPs) with IL results in distinctive properties, which may offer enormous utility in the field of biomedical research due to the effortless separation of MNPs by an external magnetic field. Detailed characterization of MNPs including Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), and scanning electron microscopy (SEM) was carried out. The biomolecular interactions of Fe3O4 and Fe3O4-CHOH NPs with cytochrome c (Cyt c) were studied in detail using various spectroscopic and microscopic techniques. From spectroscopic studies, it can be concluded that the secondary structure of Cyt c is more stable in the presence of Fe3O4-CHOH NPs than Fe3O4 NPs. The binding constant of Cyt c in the presence of MNPs was also calculated using the Benesi-Hildebrand equation. Furthermore, dynamic light scattering (DLS), ζ-potential, and microscopic studies were performed to study the interaction of Cyt c with MNPs. These studies provided evidence favoring the formation of bionanoconjugates of Cyt c with MNPs. Moreover, the enzymatic activity of Cyt c increases in the presence of both MNPs. The peroxidase activity of Cyt c in MNPs explicitly elucidates that the enzyme is preserved for a long time in the presence of Fe3O4-CHOH NPs. Later on, TEM and field emission scanning electron microscopy (FESEM) were also performed to gather more information regarding the morphology of Cyt c in the presence of MNPs.

Emerging Role of Extracellular Vesicles in Intercellular Communication in the Brain: Implications for Neurodegenerative Diseases and Therapeutics

Extracellular vesicles (EVs) are minute lipid-bilayer sacs discharged by cells, encompassing a diverse array of proteins, nucleic acids, and lipids. The identification of EVs as pivotal agents in intercellular communication has sparked compelling research pathways in the realms of cell biology and neurodegenerative diseases. Utilizing EVs for medicinal reasons has garnered interest due to the adaptability of EV-mediated communication. EVs can be classified based on their physical characteristics, biochemical composition, or cell of origin following purification. This review delves into the primary sub-types of EVs, providing an overview of the biogenesis of each type. Additionally, it explores the diverse environmental conditions triggering EV release and the originating cells, including stem cells and those from the Central Nervous System. Within the brain, EVs play a pivotal role as essential mediators of intercellular communication, significantly impacting synaptic plasticity, brain development, and the etiology of neurological diseases. Their potential diagnostic and therapeutic applications in various brain-related conditions are underscored, given their ability to carry specific cargo. Specially engineered EVs hold promise for treating diverse diseases, including neurodegenerative disorders. This study primarily emphasizes the diagnostic and potential therapeutic uses of EVs in neurological disorders such as Alzheimer's Disease, Huntington's Disease, Parkinson's Disease, Amyotrophic Lateral Sclerosis, and Prions disease. It also summarizes innovative techniques for detecting EVs in the brain, suggesting that EVs could serve as non-invasive biomarkers for early detection, disease monitoring, and prognosis in neurological disorders.

Towards the Clinical Implementation of Extracellular Vesicle-Based Biomarker Assays for Cancer

BACKGROUND

Substantial research has been devoted to elucidating the role of extracellular vesicles (EVs) in the different hallmarks of cancer. Consequently, EVs are increasingly explored as a source of cancer biomarkers in body fluids. However, the heterogeneity in EVs, the complexity of body fluids, and the diversity in methods available for EV analysis, challenge the development and translation of EV-based biomarker assays.

CONTENT

Essential steps in EV-associated biomarker development are emphasized covering biobanking, biomarker discovery, verification and validation, and clinical implementation. A meticulous study design is essential and ideally results from close interactions between clinicians and EV researchers. A plethora of different EV preparation protocols exists which warrants quality control and transparency to ensure reproducibility and thus enable verification of EV-associated biomarker candidates identified in the discovery phase in subsequent independent cohorts. The development of an EV-associated biomarker assay requires thorough analytical and clinical validation. Finally, regulatory affairs must be considered for clinical implementation of EV-based biomarker assays.

SUMMARY

In this review, the current challenges that prevent us from exploiting the full potential of EV-based biomarker assays are identified. Guidelines and tools to overcome these hurdles are highlighted and are crucial to advance EV-based biomarker assays into clinical use.

Microscopy based methods for characterization, drug delivery, and understanding the dynamics of nanoparticles

Nanomedicine is an emerging field that exploits nanotechnology for the development of novel therapeutic and diagnostic modalities. Researches are been focussed in nanoimaging to develop noninvasive, highly sensitive, and reliable tools for diagnosis and visualization in nanomedical field. The application of nanomedicine in healthcare requires in-depth understanding of their structural, physical and morphological properties, internalization inside living system, biodistribution and localization, stability, mode of action and possible toxic health effects. Microscopic techniques including fluorescence-based confocal laser scanning microscopy, super-resolution fluorescence microscopy and multiphoton microscopy; optical-based Raman microscopy, photoacoustic microscopy and optical coherence tomography; photothermal microscopy; electron microscopy (transmission electron microscope and scanning electron microscope); atomic force microscopy; X-ray microscopy and, correlative multimodal imaging are recognized as an indispensable tool in material research and aided in numerous discoveries. Microscopy holds great promise in detecting the fundamental structures of nanoparticles (NPs) that determines their performance and applications. Moreover, the intricate details that allows assessment of chemical composition, surface topology and interfacial properties, molecular, microstructure, and micromechanical properties are also elucidated. With plethora of applications, microscopy-based techniques have been used to characterize novel NPs alongwith their proficient designing and adoption of safe strategies to be exploited in nanomedicine. Consequently, microscopic techniques have been extensively used in the characterization of fabricated NPs, and their biomedical application in diagnostics and therapeutics. The present review provides an overview of the microscopy-based techniques for in vitro and in vivo application in nanomedical investigation alongwith their challenges and advancement to meet the limitations of conventional methods.

Leukemia-derived Exosomes Can Induce Responses Related to Tumorigenesis on Non-tumoral Astrocytes

Cancer is the second cause of disability and death worldwide. Identifying communication between cancer cells and normal cells can shed light on the underlying metastatic mechanisms. Among different suspected mechanisms, exosomes derived from cancer cells have been introduced as a main key player in metastatic processes. To this point, we evaluated the effects of exosomes derived from the leukemia nalm6 cell line on astrocytes behavior, such as proliferation and inflammatory pathways. To assess astrocyte responses, data were obtained by MTT, Annexin/PI to indicate proliferation and apoptosis. Further analyses were performed by Real-time PCR and western blot to assess the expression of IL6, IL1β, NFkβ, TNFα, and aquaporin-4 (AQP4). Our results demonstrated that the proliferation of astrocytes was significantly increased when treated with exosomes derived from Nalm6 cells. We also found that the expression of IL6, IL1β, NFkβ, and TNFα were significantly increased at the mRNA level when exposed to exosomes derived from Nalm6 cells. Finally, the mRNA and protein levels of AQP4 were profoundly increased after being treated by exosomes derived from Nalm6 cells. To sum up, our data indicated that the secretion of cancer cells could induce responses related to tumorigenesis. However, further studies on this topic are warranted to clarify exosomes' role in metastasis.

Exploring the Versatility of Exosomes: A Review on Isolation, Characterization, Detection Methods, and Diverse Applications

Extracellular vesicles (EVs) are crucial mediators of intercellular communication and can be classified based on their physical properties, biomolecular structure, and origin. Among EVs, exosomes have garnered significant attention due to their potential as therapeutic and diagnostic tools. Exosomes are released via fusion of multivesicular bodies on plasma membranes and can be isolated from various biofluids using methods such as differential ultracentrifugation, immune affinity capture, ultrafiltration, and size exclusion chromatography. Herein, an overview of different techniques for exosome characterization and isolation, as well as the diverse applications of exosome detection, including their potential use in drug delivery and disease diagnosis, is provided. Additionally, we discuss the emerging field of exosome detection by sensors, which offers an up-and-coming avenue for point-of-care diagnostic tools development. Overall, this review aims to provide a exhaustive and up-to-date summary of the current state of exosome research.

Plant exosome nanovesicles (PENs): green delivery platforms

Natural plants have been attracting increasing attention in biomedical research due to their numerous benefits. Plant exosome-derived vesicles, some of the plant's components, are small nanoscale vesicles secreted by plant cells. These vesicles are rich in bioactive substances and play significant roles in intercellular communication, information transfer, and maintaining homeostasis in organisms. They also hold promise for treating diseases, and their vesicular structures make them suitable carriers for drug delivery, with large-scale production feasible. Therefore, this paper aims to provide an overview of nanovesicles from different plant sources and their extraction methods. We also outline the biological activities of nanovesicles, including their anti-inflammatory, anti-viral, and anti-tumor properties, and systematically introduce their applications in drug delivery. These applications include transdermal delivery, targeted drug delivery, gene delivery, and their potential use in the modern food industry. This review provides new ideas and methods for future research on plant exosomes, including their empowerment by artificial intelligence and gene editing, as well as their potential application in the biomedicine, food, and agriculture industries.

Guidelines for the purification and characterization of extracellular vesicles of parasites

Parasites are responsible for the most neglected tropical diseases, affecting over a billion people worldwide (WHO, 2015) and accounting for billions of cases a year and responsible for several millions of deaths. Research on extracellular vesicles (EVs) has increased in recent years and demonstrated that EVs shed by pathogenic parasites interact with host cells playing an important role in the parasite's survival, such as facilitation of infection, immunomodulation, parasite adaptation to the host environment and the transfer of drug resistance factors. Thus, EVs released by parasites mediate parasite-parasite and parasite-host intercellular communication. In addition, they are being explored as biomarkers of asymptomatic infections and disease prognosis after drug treatment. However, most current protocols used for the isolation, size determination, quantification and characterization of molecular cargo of EVs lack greater rigor, standardization, and adequate quality controls to certify the enrichment or purity of the ensuing bioproducts. We are now initiating major guidelines based on the evolution of collective knowledge in recent years. The main points covered in this position paper are methods for the isolation and molecular characterization of EVs obtained from parasite-infected cell cultures, experimental animals, and patients. The guideline also includes a discussion of suggested protocols and functional assays in host cells.

Programming Cell-Derived Vesicles with Enhanced Immunomodulatory Properties

Tumor-associated macrophages are the predominant immune cells present in the tumor microenvironment and mostly exhibit a pro-tumoral M2-like phenotype. However, macrophage biology is reversible allowing them to acquire an anti-tumoral M1-like phenotype in response to external stimuli. A potential therapeutic strategy for treating cancer may be achieved by modulating macrophages from an M2 to an M1-like phenotype with the tumor microenvironment. Here, programmed nanovesicles are generated as an immunomodulatory therapeutic platform with the capability to re-polarize M2 macrophages toward a proinflammatory phenotype. Programmed nanovesicles are engineered from cellular membranes to have specific immunomodulatory properties including the capability to bidirectionally modulate immune cell polarization. These programmed nanovesicles decorated with specific membrane-bound ligands can be targeted toward specific cell types including immune cells. Macrophage-derived vesicles are engineered to enhance immune cell reprogramming toward a proinflammatory phenotype.

Extracellular Vesicles: Techniques and Biomedical Applications Related to Single Vesicle Analysis

Extracellular vesicles (EVs) are extensively dispersed lipid bilayer membrane vesicles involved in the delivery and transportation of molecular payloads to certain cell types to facilitate intercellular interactions. Their significant roles in physiological and pathological processes make EVs outstanding biomarkers for disease diagnosis and treatment monitoring as well as ideal candidates for drug delivery. Nevertheless, differences in the biogenesis processes among EV subpopulations have led to a diversity of biophysical characteristics and molecular cargos. Additionally, the prevalent heterogeneity of EVs has been found to substantially hamper the sensitivity and accuracy of disease diagnosis and therapeutic monitoring, thus impeding the advancement of clinical applications. In recent years, the evolution of single EV (SEV) analysis has enabled an in-depth comprehension of the physical properties, molecular composition, and biological roles of EVs at the individual vesicle level. This review examines the sample acquisition tactics prior to SEV analysis, i.e., EV isolation techniques, and outlines the current state-of-the-art label-free and label-based technologies for SEV identification. Furthermore, the challenges and prospects of biomedical applications based on SEV analysis are systematically discussed.

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.

Relevance of multilamellar and multicompartmental vesicles in biological fluids: understanding the significance of proportional variations and disease correlation

Extracellular vesicles (EVs) have garnered significant interest in the field of biomedical science due to their potential applications in therapy and diagnosis. These vesicles participate in cell-to-cell communication and carry a diverse range of bioactive cargo molecules, such as nucleic acids, proteins, and lipids. These cargoes play essential roles in various signaling pathways, including paracrine and endocrine signaling. However, our understanding of the morphological and structural features of EVs is still limited. EVs could be unilamellar or multilamellar or even multicompartmental structures. The relative proportions of these EV subtypes in biological fluids have been associated with various human diseases; however, the mechanism remains unclear. Cryo-electron microscopy (cryo-EM) holds great promise in the field of EV characterization due to high resolution properties. Cryo-EM circumvents artifacts caused by fixation or dehydration, allows for the preservation of native conformation, and eliminates the necessity for staining procedures. In this review, we summarize the role of EVs biogenesis and pathways that might have role on their structure, and the role of cryo-EM in characterization of EVs morphology in different biological samples and integrate new knowledge of the alterations of membranous structures of EVs which could be used as biomarkers to human diseases.

Exosomal delivery of cannabinoids against cancer

Exosomes are extracellular vesicles (EVs) originating from endosomes that play a role in cellular communication. These vesicles which mimic the parental cells that release them are promising candidates for targeted drug delivery and therapeutic applications against cancer because of their favorable biocompatibility, specific targeting, low toxicity, and immunogenicity. Currently, Delta-9-tetrahydrocannabinol (THC), cannabidiol (CBD) and other cannabinoids (e.g., CBG, THCV, CBC), are being explored for their anticancer and anti-proliferative properties. Several mechanisms, including cell cycle arrest, proliferation inhibition, activation of autophagy and apoptosis, inhibition of adhesion, metastasis, and angiogenesis have been proposed for their anticancer activity. EVs could be engineered as cannabinoid delivery systems for tumor-specificity leading to superior anticancer effects. This review discusses current techniques for EV isolation from various sources, characterization and strategies to load them with cannabinoids. More extensively, we culminate information available on different sources of EVs that have anticancer activity, mechanism of action of cannabinoids against various wild type and resistant tumors and role of CBD in histone modifications and cancer epigenetics. We have also enumerated the role of EVs containing cannabinoids against various tumors and in chemotherapy induced neuropathic pain.

Extracellular vesicle-matrix interactions

The extracellular matrix in microenvironments harbors a variety of signals to control cellular functions and the materiality of tissues. Most efforts to synthetically reconstitute the matrix by biomaterial design have focused on decoupling cell-secreted and polymer-based cues. Cells package molecules into nanoscale lipid membrane-bound extracellular vesicles and secrete them. Thus, extracellular vesicles inherently interact with the meshwork of the extracellular matrix. In this Review, we discuss various aspects of extracellular vesicle-matrix interactions. Cells receive feedback from the extracellular matrix and leverage intracellular processes to control the biogenesis of extracellular vesicles. Once secreted, various biomolecular and biophysical factors determine whether extracellular vesicles are locally incorporated into the matrix or transported out of the matrix to be taken up by other cells or deposited into tissues at a distal location. These insights can be utilized to develop engineered biomaterials where EV release and retention can be precisely controlled in host tissue to elicit various biological and therapeutic outcomes.

Technological aspects of manufacturing and analytical control of biological nanoparticles

Extracellular vesicles (EVs) are cell-derived biological nanoparticles that gained great interest for drug delivery. EVs have numerous advantages compared to synthetic nanoparticles, such as ideal biocompatibility, safety, ability to cross biological barriers and surface modification via genetic or chemical methods. On the other hand, the translation and the study of these carriers resulted difficult, mostly because of significant issues in up-scaling, synthesis and impractical methods of quality control. However, current manufacturing advances enable EV packaging with any therapeutic cargo, including DNA, RNA (for RNA vaccines and RNA therapeutics), proteins, peptides, RNA-protein complexes (including gene-editing complexes) and small molecules drugs. To date, an array of new and upgraded technologies have been introduced, substantially improving EV production, isolation, characterization and standardization. The used-to-be "gold standards" of EV manufacturing are now outdated, and the state-of-art requires extensive revision. This review re-evaluates the pipeline for EV industrial production and provides a critical overview of the modern technologies required for their synthesis and characterization.

Protein corona and exosomes: new challenges and prospects

Recent advances in extracellular vesicle (EVs) detection and isolation methods have led to the development of novel therapeutic modalities. Among different types of EVs, exosomes (Exos) can transfer different signaling biomolecules and exhibit several superior features compared to whole-cell-based therapies. Therapeutic factors are normally loaded into the Exo lumen or attached to their surface for improving the on-target delivery rate and regenerative outcomes. Despite these advantages, there are several limitations in the application of Exos in in vivo conditions. It was suggested that a set of proteins and other biological compounds are adsorbed around Exos in aqueous phases and constitute an external layer named protein corona (PC). Studies have shown that PC can affect the physicochemical properties of synthetic and natural nanoparticles (NPs) after introduction in biofluids. Likewise, PC is generated around EVs, especially Exos in in vivo conditions. This review article is a preliminary attempt to address the interfering effects of PC on Exo bioactivity and therapeutic effects. Video Abstract.

Placenta-Derived Extracellular Vesicles in Pregnancy Complications and Prospects on a Liquid Biopsy for Hemoglobin Bart's Disease

Extracellular vesicles (EVs) are nano-scaled vesicles released from all cell types into extracellular fluids and specifically contain signature molecules of the original cells and tissues, including the placenta. Placenta-derived EVs can be detected in maternal circulation at as early as six weeks of gestation, and their release can be triggered by the oxygen level and glucose concentration. Placental-associated complications such as preeclampsia, fetal growth restriction, and gestational diabetes have alterations in placenta-derived EVs in maternal plasma, and this can be used as a liquid biopsy for the diagnosis, prediction, and monitoring of such pregnancy complications. Alpha-thalassemia major ("homozygous alpha-thalassemia-1") or hemoglobin Bart's disease is the most severe form of thalassemia disease, and this condition is lethal for the fetus. Women with Bart's hydrops fetalis demonstrate signs of placental hypoxia and placentomegaly, thereby placenta-derived EVs provide an opportunity for a non-invasive liquid biopsy of this lethal condition. In this article, we introduced clinical features and current diagnostic markers of Bart's hydrops fetalis, extensively summarize the characteristics and biology of placenta-derived EVs, and discuss the challenges and opportunities of placenta-derived EVs as part of diagnostic tests for placental complications focusing on Bart's hydrop fetalis.

A guide to mass spectrometric analysis of extracellular vesicle proteins for biomarker discovery

Exosomes (small extracellular vesicles) in living organisms play an important role in processes such as cell proliferation or intercellular communication. Recently, exosomes have been extensively investigated for biomarker discoveries for various diseases. An important aspect of exosome analysis involves the development of enrichment methods that have been introduced for successful isolation of exosomes. These methods include ultracentrifugation, size exclusion chromatography, polyethylene glycol-based precipitation, immunoaffinity-based enrichment, ultrafiltration, and asymmetric flow field-flow fractionation among others. To confirm the presence of exosomes, various characterization methods have been utilized such as Western blot analysis, atomic force microscopy, electron microscopy, optical methods, zeta potential, visual inspection, and mass spectrometry. Recent advances in high-resolution separations, high-performance mass spectrometry and comprehensive proteome databases have all contributed to the successful analysis of exosomes from patient samples. Herein we review various exosome enrichment methods, characterization methods, and recent trends of exosome investigations using mass spectrometry-based approaches for biomarker discovery.

Cellular communication through extracellular vesicles and lipid droplets

Cellular communication is essential for effective coordination of biological processes. One major form of intercellular communication occurs via the release of extracellular vesicles (EVs). These vesicles mediate intercellular communication through the transfer of their cargo and are actively explored for their role in various diseases and their potential therapeutic and diagnostic applications. Conversely, lipid droplets (LDs) are vesicles that transfer cargo within cells. Lipid droplets play roles in various diseases and evidence for their ability to transfer cargo between cells is emerging. To date, there has been little interdisciplinary research looking at the similarities and interactions between these two classes of small lipid vesicles. This review will compare the commonalities and differences between EVs and LDs including their biogenesis and secretion, isolation and characterisation methodologies, composition, and general heterogeneity and discuss challenges and opportunities in both fields.

Label-Free Identification of Exosomes using Raman Spectroscopy and Machine Learning

Exosomes, nano-sized extracellular vesicles (EVs) secreted from cells, carry various cargo molecules reflecting their cells of origin. As EV content, structure, and size are highly heterogeneous, their classification via cargo molecules by determining their origin is challenging. Here, a method is presented combining surface-enhanced Raman spectroscopy (SERS) with machine learning algorithms to employ the classification of EVs derived from five different cell lines to reveal their cellular origins. Using an artificial neural network algorithm, it is shown that the label-free Raman spectroscopy method's prediction ratio correlates with the ratio of HT-1080 exosomes in the mixture. This machine learning-assisted SERS method enables a new direction through label-free investigation of EV preparations by differentiating cancer cell-derived exosomes from those of healthy. This approach will potentially open up new avenues of research for early detection and monitoring of various diseases, including cancer.

Nanostructures and Nanotechnologies for the Detection of Extracellular Vesicle

Liquid biopsy has been taken as a minimally invasive examination and a promising surrogate to the clinically applied tissue-based test for the diagnosis and molecular analysis of cancer. Extracellular vesicles (EVs) carry complex molecular information from the tumor, allowing for the multicomponent analysis of cancer and would be beneficial to personalized medicine. In this review, the advanced nanomaterials and nanotechniques for the detection and molecular profiling of EVs, highlight the advantages of nanotechnology in the high-purity isolation and the high-sensitive and high-specific identification of EVs, are summarized. An outlook on the clinical application of nanotechnology-based liquid biopsy in the diagnosis, prognostication, and surveillance of cancer is also provided. It provides information for developing liquid biopsy based on EVs by discussing the advantages and challenges of functionalized nanomaterials and various nanotechnologies.

Small extracellular vesicles in breast cancer brain metastasis and the prospect of clinical application

Extracellular vesicles (EVs) are nanoscale extracellular particles that have received widespread scientific attention for carrying a variety of biomolecules such as nucleic acids and proteins and participating in the process of intercellular information exchange, making them become a research hotspot due to their potential diagnostic value. Breast cancer is the leading cause of cancer-related death in women, approximately 90% of patient deaths are due to metastasis complications. Brain metastasis is an important cause of mortality in breast cancer patients, about 10-15% of breast cancer patients will develop brain metastasis. Therefore, early prevention of brain metastasis and the development of new treatments are crucial. Small EVs have been discovered to be involved in the entire process of breast cancer brain metastasis (BCBM), playing an important role in driving organ-specific metastasis, forming pre-metastatic niches, disrupting the blood-brain barrier, and promoting metastatic tumor cell proliferation. We summarize the mechanisms of small EVs in the aforementioned pathological processes at the cellular and molecular levels, and anticipate their potential applications in the treatment of breast cancer brain metastasis, with the hope of providing new ideas for the precise treatment of breast cancer brain metastasis.

Integrating Cutting-Edge Methods to Oral Cancer Screening, Analysis, and Prognosis

Oral cancer (OC) has become a significant barrier to health worldwide due to its high morbidity and mortality rates. OC is among the most prevalent types of cancer that affect the head and neck region, and the overall survival rate at 5 years is still around 50%. Moreover, it is a multifactorial malignancy instigated by genetic and epigenetic variabilities, and molecular heterogeneity makes it a complex malignancy. Oral potentially malignant disorders (OPMDs) are often the first warning signs of OC, although it is challenging to predict which cases will develop into malignancies. Visual oral examination and histological examination are still the standard initial steps in diagnosing oral lesions; however, these approaches have limitations that might lead to late diagnosis of OC or missed diagnosis of OPMDs in high-risk individuals. The objective of this review is to present a comprehensive overview of the currently used novel techniques viz., liquid biopsy, next-generation sequencing (NGS), microarray, nanotechnology, lab-on-a-chip (LOC) or microfluidics, and artificial intelligence (AI) for the clinical diagnostics and management of this malignancy. The potential of these novel techniques in expanding OC diagnostics and clinical management is also reviewed.

Advances in Extracellular Vesicle Nanotechnology for Precision Theranostics

Extracellular vesicles (EVs) have increasingly been recognized as important cell surrogates influencing many pathophysiological processes, including cellular homeostasis, cancer progression, neurologic disease, and infectious disease. These behaviors enable EVs broad application prospects for clinical application in disease diagnosis and treatment. Many studies suggest that EVs are superior to conventional synthetic carriers in terms of drug delivery and circulating biomarkers for early disease diagnosis, opening up new frontiers for modern theranostics. Despite these clinical potential, EVs containing diverse cellular components, such as nucleic acids, proteins, and metabolites are highly heterogeneous and small size. The limitation of preparatory, engineering and analytical technologies for EVs poses technical barriers to clinical translation. This article aims at present a critical overview of emerging technologies in EVs field for biomedical applications and challenges involved in their clinic translations. The current methods for isolation and identification of EVs are discussed. Additionally, engineering strategies developed to enhance scalable production and improved cargo loading as well as tumor targeting are presented. The superior clinical potential of EVs, particularly in terms of different cell origins and their application in the next generation of diagnostic and treatment platforms, are clarified.

Advances in exosome analysis

There is growing demand for novel biomarkers that detect early stage disease as well as monitor clinical management and therapeutic strategies. Exosome analysis could provide the next advance in attaining that goal. Exosomes are membrane encapsulated biologic nanometric-sized particles of endocytic origin which are released by all cell types. Unfortunately, exosomes are exceptionally challenging to characterize with current technologies. Exosomes are between 30 and 200nm in diameter, a size that makes them out of the sensitivity range to most cell-oriented sorting or analysis platforms, i.e., traditional flow cytometers. The most common methods for targeting exosomes to date typically involve purification followed by the characterization and the specific determination of their cargo. The whole procedure is time consuming, requiring thus skilled personnel as well as laboratory facilities and benchtop instrumentation. The most relevant methodology for exosome isolation, characterization and quantification is addressed in this chapter, including the most up-to-date approaches to explore the potential usefulness of exosomes as biomarkers in liquid biopsies and in advanced nanomedicine.

Nanoscale biophysical properties of small extracellular vesicles from senescent cells using atomic force microscopy, surface potential microscopy, and Raman spectroscopy

Cells secrete extracellular vesicles (EVs) carrying cell-of-origin markers to communicate with surrounding cells. EVs regulate physiological processes ranging from intercellular signaling to waste management. However, when senescent cells (SnCs) secrete EVs, the EVs, which are newly regarded as senescence-associated secretory phenotype (SASP) factors, can evoke inflammation, senescence induction, and metabolic disorders in neighboring cells. Unlike other soluble SASP factors, the biophysical properties of EVs, including small EVs (sEVs), derived from SnCs have not yet been investigated. In this study, sEVs were extracted from a human IMR90 lung fibroblast in vitro senescence model. Their biomechanical properties were mapped using atomic force microscopy-based quantitative nanomechanical techniques, surface potential microscopy, and Raman spectroscopy. The surfaces of sEVs derived from SnCs are slightly stiffer but their cores are softer than those of sEVs secreted from non-senescent cells (non-SnCs). This inversely proportional relationship between deformation and stiffness, attributed to a decrease in the concentration of genetic and protein materials inside the vesicles and the adsorption of positively charged SASP factors onto the vesicle surfaces, respectively, was found to be a peculiar characteristic of SnC-derived sEVs. Our results demonstrate that the biomechanical properties of SnC-derived sEVs differ from those of non-SnC-derived sEVs and provide insight into the mechanisms underlying their formation and composition.

Methods to analyze extracellular vesicles at single particle level

Extracellular vesicles (EVs) are nano-sized vesicles derived from cells that transport biomaterials between cells through biofluids. Due to their biological role and components, they are considered as potential drug carriers and for diagnostic applications. Today's advanced nanotechnology enables single-particle-level analysis that was difficult in the past due to its small size below the diffraction limit. Single EV analysis reveals the heterogeneity of EVs, which could not be discovered by various ensemble analysis methods. Understanding the characteristics of single EVs enables more advanced pathological and biological researches. This review focuses on the advanced techniques employed for EV analysis at the single particle level and describes the principles of each technique.

Engineered stem cell exosomes for oral and maxillofacial wound healing

Wound healing of the oral and maxillofacial area affects the quality of life and mental health of the patient; therefore, effective therapies are required to promote wound healing. However, traditional treatment methods have limited efficacy. Exosomes secreted by stem cells used for oral and maxillofacial wound healing have shown outstanding results. Stem cell-derived exosomes possess the regenerative and repair ability of stem cells. Moreover, they are nontumorigenic and have good biosafety. However, the application of natural stem cell exosomes is limited owing to their low yield, impurity, lack of targeting, and low drug delivery rate. Many modification methods have been developed to engineered stem cell exosomes with beneficial properties, such as modifying parent cells and directly processing stem cell exosomes. These methods include coincubation, genetic engineering, electroporation, ultrasound, and artificial synthesis of engineered stem cell exosomes. These engineered stem cell exosomes can cargo nucleic acids, proteins, and small molecules. This gives them anti-inflammatory and cell proliferation regulatory abilities and enables the targeted promotion of efficient soft tissue repair after trauma. Engineered stem cell exosomes can decrease inflammation, promote fibroblast proliferation, and angiogenesis, and decrease scar formation to promote oral and maxillofacial wound healing, including diabetic and burn wounds. Thus, engineered stem cell exosomes are an effective treatment that has the potential for oral and maxillofacial wound healing.

The roles of small extracellular vesicles as prognostic biomarkers and treatment approaches in triple-negative breast cancer

Triple-negative breast cancer (TNBC) is a particularly aggressive and invasive breast cancer subtype and is associated with poor clinical outcomes. Treatment approaches for TNBC remain limited partly due to the lack of expression of well-known molecular targets. Small extracellular vesicles (sEVs) carrying a variety of bioactive contents play an important role in intercellular communications. The biomolecules including nucleic acids, proteins, and metabolites can be transferred locally or systematically to recipient cells and regulate their biological states and are involved in physiological and pathological processes. Recently, despite the extensive attraction to the physiological functions of sEVs, few studies focus on the roles of sEVs in TNBC. In this review, we will summarize the involvement of sEVs in the tumor microenvironment of TNBC. Moreover, we will discuss the potential roles of sEVs as diagnostic markers and treatment therapy in this heterogeneous breast cancer subtype. We finally summarize the clinical application of sEVs in TNBC.

Diagnosis of hepatocellular carcinoma based on salivary protein glycopatterns and machine learning algorithms

Objectives

Hepatocellular carcinoma (HCC) is difficult to diagnose early and progresses rapidly, making it one of the most deadly malignancies worldwide. This study aimed to evaluate whether salivary glycopattern changes combined with machine learning algorithms could help in the accurate diagnosis of HCC.

Methods

Firstly, we detected the alteration of salivary glycopatterns by lectin microarrays in 118 saliva samples. Subsequently, we constructed diagnostic models for hepatic cirrhosis (HC) and HCC using three machine learning algorithms: Least Absolute Shrinkage and Selector Operation, Support Vector Machine (SVM), and Random Forest (RF). Finally, the performance of the diagnostic models was assessed in an independent validation cohort of 85 saliva samples by a series of evaluation metrics, including area under the receiver operator curve (AUC), accuracy, specificity, and sensitivity.

Results

We identified alterations in the expression levels of salivary glycopatterns in patients with HC and HCC. The results revealed that the glycopatterns recognized by 22 lectins showed significant differences in the saliva of HC and HCC patients and healthy volunteers. In addition, after Boruta feature selection, the best predictive performance was obtained with the RF algorithm for the construction of models for HC and HCC. The AUCs of the RF-HC model and RF-HCC model in the validation cohort were 0.857 (95% confidence interval [CI]: 0.780–0.935) and 0.886 (95% CI: 0.814–0.957), respectively.

Conclusions

Detecting alterations in salivary protein glycopatterns with lectin microarrays combined with machine learning algorithms could be an effective strategy for diagnosing HCC in the future.

Extracellular Vesicles: A New Frontier for Cardiac Repair

The ability of extracellular vesicles (EVs) to regulate a broad range of cellular processes has recently been used to treat diseases. Growing evidence indicates that EVs play a cardioprotective role in heart disease by activating beneficial signaling pathways. Multiple functional components of EVs and intracellular molecular mechanisms are involved in the process. To overcome the shortcomings of native EVs such as their heterogeneity and limited tropism, a series of engineering approaches has been developed to improve the therapeutic efficiency of EVs. In this review, we present an overview of the research and future directions for EVs-based cardiac therapies with an emphasis on EVs-mediated delivery of therapeutic agents. The advantages and limitations of various modification strategies are discussed, and possible opportunities for improvement are proposed. An in-depth understanding of the endogenous properties of EVs and EVs engineering strategies could lead to a promising cell-free therapy for cardiac repair.

Exosomics in oral cancer diagnosis, prognosis, and therapeutics - An emergent and imperative non-invasive natural nanoparticle-based approach

Exosomes- the natural nanoparticles belonging to heterogeneous vesicles are released via nearly all sorts of cells, including tumour cells, to oprate intercellular communication. Selective packaging of exosomes amid nucleic acids, phospholipids, and proteins makes them ideal for intercellular communications occurring among different cells. The existence of exosomes has been validated in various biofluids, including saliva. Being non-invasive and in direct contact with oral malignant cells, saliva establishes itself as a preeminent source of early cancer biomarkers. In context, the role and providence of both recipient and donor secreting cells are persuaded through exosomal cargo.Several studies have emphasized the influence of exosomal contents in different stages of cancer development, reconciling interactions between tumour cells and their surrounding niche. More explicitly, a transformation of exosomal contents such as nucleic acids, lipids, and proteins can endorse tumour progression and help ascertain a secluded pre-metastatic niche crammed with substances that errand cancer cell proliferation,angiogenesis, metastasis, and drug resistance. The blooming field of exosomes has directed the evolution of high-end isolation and characterization techniques along with the development of an entirely new field- exosomics that comprises complete analysis of exosomal cargo in various physiological conditions, including oral cancer. Researchers have discovered multiple pathways involved in exosome biogenesis to understand numerous events associated with cancer progression. Tissue-specific packaging of exosomes makes them a novel source of prognostic and diagnostic biomarkers and potential therapeutic targets. The extent of the current review confers the contemporary perception of the versatile task of exosomes, especially salivary exosomes, as potential biomarkers in the progression and diagnosis as well as therapeutics of oral cancers and their potential employment in clinical applications.

Triple negative breast cancer-derived small extracellular vesicles as modulator of biomechanics in target cells

Extracellular vesicle (EV) mediated communication has recently been proposed as one of the pivotal routes in the development of cancer metastasis. EVs are nano-sized vesicles swapped between cells, carrying a biologically active content that can promote tumor-induced immune suppression, metastasis and angiogenesis. Thus, EVs constitute a potential target in cancer therapy. However, their role in triggering the premetastatic niche and in tumor spreading is still unclear. Here, we focused on the EV ability to modulate the biomechanical properties of target cells, known to play a crucial role in metastatic spreading. To this purpose, we isolated and thoroughly characterized triple-negative breast cancer (TNBC)-derived small EVs. We then evaluated variations in the mechanical properties (cell stiffness, cytoskeleton/nuclear/morphology and Yap activity rearrangements) of non-metastatic breast cancer MCF7 cells upon EV treatment. Our results suggest that TNBC-derived small EVs are able to directly modify MCF7 cells by inducing a decrease in cell stiffness, rearrangements in cytoskeleton, focal adhesions and nuclear/cellular morphology, and an increase in Yap downstream gene expression. Testing the biomechanical response of cells after EV addition might represent a new functional assay in metastatic cancer framework that can be exploited for future application both in diagnosis and in therapy.

Integrated Strategies for a Holistic View of Extracellular Vesicles

Extracellular vesicles (EVs) are receiving increasing attention for their role in spreading both beneficial and harmful information during cell-cell communication. The complexity and heterogeneity of the origin of EVs make integrated molecular, structural, and functional studies extremely challenging but necessary at the same time. In fact, a comprehensive interdisciplinary approach is needed to correlate the features of EVs, target cells/organs, and the pathophysiological outcomes exerted by the EVs' actions. Based on these premises, after introducing a brief state-of-the-art outline on the current analytical approaches exploited to characterize EVs, this review aims to highlight the effectiveness of those studies where authors put in correlation the diverse EV data collected from different points of view. Although these examples are still just a few, they still represent an excellent starting point to be taken as a reference in the perspective for improving the correlation among EV-related clinical aspects. Of course, to fully reach this goal, several points need to be further improved and developed. Undoubtedly, new avenues in diagnostic, prognostic, and therapeutic applications by EVs will be initiated by integrative strategies, combining biophysical approaches, high-throughput omics technologies, and computational models.

Saliva Diagnostics

Cancer remains one of the leading causes of death, and early detection of this disease is crucial for increasing survival rates. Although cancer can be diagnosed following tissue biopsy, the biopsy procedure is invasive; liquid biopsy provides an alternative that is more comfortable for the patient. While blood, urine, and cerebral spinal fluid can all be used as a source of liquid biopsy, saliva is an ideal source of body fluid that is readily available and easily collected in the most noninvasive manner. Characterization of salivary constituents in the disease setting provides critical data for understanding pathophysiology and the evaluation of diagnostic potential. The aim of saliva diagnostics is therefore to develop a rapid and noninvasive detection of oral and systemic diseases that could be used together with compact analysis systems in the clinic to facilitate point-of-care diagnostics.

Extending applications of AFM to fluidic AFM in single living cell studies

In this article, a review of a series of applications of atomic force microscopy (AFM) and fluidic Atomic Force Microscopy (fluidic AFM, hereafter fluidFM) in single-cell studies is presented. AFM applications involving single-cell and extracellular vesicle (EV) studies, colloidal force spectroscopy, and single-cell adhesion measurements are discussed. FluidFM is an offshoot of AFM that combines a microfluidic cantilever with AFM and has enabled the research community to conduct biological, pathological, and pharmacological studies on cells at the single-cell level in a liquid environment. In this review, capacities of fluidFM are discussed to illustrate (1) the speed with which sequential measurements of adhesion using coated colloid beads can be done, (2) the ability to assess lateral binding forces of endothelial or epithelial cells in a confluent cell monolayer in an appropriate physiological environment, and (3) the ease of measurement of vertical binding forces of intercellular adhesion between heterogeneous cells. Furthermore, key applications of fluidFM are reviewed regarding to EV absorption, manipulation of a single living cell by intracellular injection, sampling of cellular fluid from a single living cell, patch clamping, and mass measurements of a single living cell.

Recent advances in optical label-free characterization of extracellular vesicles

Extracellular vesicles (EVs) are complex biological nanoparticles endogenously secreted by all eukaryotic cells. EVs carry a specific molecular cargo of proteins, lipids, and nucleic acids derived from cells of origin and play a significant role in the physiology and pathology of cells, organs, and organisms. Upon release, they may be found in different body fluids that can be easily accessed via noninvasive methodologies. Due to the unique information encoded in their molecular cargo, they may reflect the state of the parent cell and therefore EVs are recognized as a rich source of biomarkers for early diagnostics involving liquid biopsy. However, body fluids contain a mixture of EVs released by different types of healthy and diseased cells, making the detection of the EVs of interest very challenging. Recent research efforts have been focused on the detection and characterization of diagnostically relevant subpopulations of EVs, with emphasis on label-free methods that simplify sample preparation and are free of interfering signals. Therefore, in this paper, we review the recent progress of the label-free optical methods employed for the detection, counting, and morphological and chemical characterization of EVs. We will first briefly discuss the biology and functions of EVs, and then introduce different optical label-free techniques for rapid, precise, and nondestructive characterization of EVs such as nanoparticle tracking analysis, dynamic light scattering, atomic force microscopy, surface plasmon resonance spectroscopy, Raman spectroscopy, and SERS spectroscopy. In the end, we will discuss their applications in the detection of neurodegenerative diseases and cancer and provide an outlook on the future impact and challenges of these technologies to the field of liquid biopsy via EVs.

Unveiling the Native Morphology of Extracellular Vesicles from Human Cerebrospinal Fluid by Atomic Force and Cryogenic Electron Microscopy

Extracellular vesicles (EVs) are membranous structures in biofluids with enormous diagnostic/prognostic potential for application in liquid biopsies. Any such downstream application requires a detailed characterization of EV concentration, size and morphology. This study aimed to observe the native morphology of EVs in human cerebrospinal fluid after traumatic brain injury. Therefore, they were separated by gravity-driven size-exclusion chromatography (SEC) and investigated by atomic force microscopy (AFM) in liquid and cryogenic transmission electron microscopy (cryo-TEM). The enrichment of EVs in early SEC fractions was confirmed by immunoblot for transmembrane proteins CD9 and CD81. These fractions were then pooled, and the concentration and particle size distribution were determined by Tunable Resistive Pulse Sensing (around 10¹⁰ particles/mL, mode 100 nm) and Nanoparticle Tracking Analysis (around 10⁹ particles/mL, mode 150 nm). Liquid AFM and cryo-TEM investigations showed mode sizes of about 60 and 90 nm, respectively, and various morphology features. AFM revealed round, concave, multilobed EV structures; and cryo-TEM identified single, double and multi-membrane EVs. By combining AFM for the surface morphology investigation and cryo-TEM for internal structure differentiation, EV morphological subpopulations in cerebrospinal fluid could be identified. These subpopulations should be further investigated because they could have different biological functions.

Electrical characterization of tumor-derived exosomes by conductive atomic force microscopy

The physical properties of tumor-derived exosomes have gained much attention because they are helpful to better understand the exosomes in biomedicine. In this study, the conductive atomic force microscopy (C-AFM) was employed to perform the electrical characterizations of exosomes, and it obtained the topography and current images of samples simultaneously. The exosomes were absorbed onto the mica substrates coated with a gold film of 20 nm thick for obtaining the current images of samples by C-AFM in air. The results showed that the single exosomes had the weak conductivity. Furthermore, the currents on exosomes were measured at different bias voltages and pH conditions. It illustrated that the conductivity of exosomes was affected by external factors such as bias voltages and solutions with different pH values. In addition, the electrical responses of low and high metastatic potential cell-derived exosomes were also compared under different voltages and pH conditions. This work is important for better understanding the physical properties of tumor-derived exosomes and promoting the clinical applications of tumor-derived exosomes.

Target-Specific Exosome Isolation through Aptamer-Based Microfluidics

Exosomes (30–100 nm in diameter) are a group of cell-derived membrane vesicles, packaged as valuable cargo with lipid, proteins, and genetic materials from their parent cells. With the increasing interest in exosomes for diagnostic and therapeutic applications, the rapid isolation of pure exosome populations has become a hot topic. In this paper, we propose modified microchannels with aptamer in a microfluidics system for rapid and efficient isolation of exosomes by targeting exosome-carrying CD63 and PTK 7. The capture efficiency in surface-modified channels reaches around 10⁷–10⁸ particles/mL in 20 min, and purified exosomes with reliable size can be achieved.