Characterization of extracellular vesicles and synthetic nanoparticles with four orthogonal single-particle analysis platforms

Opportunities and challenges of bacterial extracellular vesicles in regenerative medicine

Extracellular vesicles (EVs) are membrane-bound vesicles that are shed or secreted from the cell membrane and enveloped by a lipid bilayer. They possess stability, low immunogenicity, and non-cytotoxicity, exhibiting extensive prospects in regenerative medicine (RM). However, natural EVs pose challenges, such as insufficient targeting capabilities, potential biosafety concerns, and limited acquisition pathways. Although engineered EVs demonstrate excellent therapeutic efficacy, challenges such as low production yield and the complexity of engineering modifications constrain their further clinical applications. Bacteria have advantages such as rapid proliferation, diverse gene editing methods, mature cultivation techniques, and relatively easy preparation of bacterial EVs (BEVs), which can be used to effectively address the challenges currently encountered in the field of EVs. This review provides a description of the biogenesis and pathophysiological functions of BEVs, and strategies for optimizing BEVs preparation to attain efficiency and safety are discussed. An analysis of natural characteristics of BEVs is also conducted to explore how to leverage their advantages or mitigate their limitations, thereby overcoming constraints on the application of BEVs in RM. In summary, engineered BEVs possess characteristics such as high production yield, excellent stability, and high drug-delivering capabilities, laying the foundation for their application in RM.

Quantitative fluorescent nanoparticle tracking analysis and nano-flow cytometry enable advanced characterization of single extracellular vesicles

Current state-of-the-art tools for analysing extracellular vesicles (EVs) offer either highly sensitive but unidimensional bulk measurements of EV components, or high-resolution multiparametric single-particle analyses which lack standardization and appropriate reference materials. This limits the accuracy of the assessment of marker abundance and overall marker distribution amongst individual EVs, and finally, the understanding of true EV heterogeneity. In this study, we aimed to define the standardized operating procedures and reference material for fluorescent characterization of EVs with two commonly used EV analytical platforms-nanoparticle tracking analysis (NTA) and nano-flow cytometry (nFCM). We achieved quantitative fluorescence analyses on ZetaView NTA and NanoAnalyzer nFCM instruments, by utilizing yellow-green FluoSpheres (FS) with assigned ERF (equivalent reference fluorophore) values. This standardization technique allowed for fluorescent EV signal to be expressed in ERF units (indicative of bound fluorescent antibodies per EV), thus enabling measurement of target protein marker abundance on individual EVs, and in the whole EV population. The NTA's and nFCM's limits of detection (LoD) were evaluated at 21 and 9 Alexa Fluor 488 (AF488) molecules, respectively. To complement the limited quantification of markers expressed in a few copies per single EV, in-line bulk fluorescence measurements with a plate reader were performed. This provided absolute marker quantification and more insightful analyses of EV heterogeneity and marker stoichiometry. The standardization method outlined in this work unlocks the full analytical potential of NTA and nFCM, enabling cross-platform data comparison. At the same time, it highlights some of the technical challenges and considerations and thus contributes to the ongoing efforts towards the development of EV analytical tools.

Increased circulating platelet-derived extracellular vesicles in severe COVID-19 disease

Coagulation disturbances are major contributors to COVID-19 pathogenicity, but limited data exist on the involvement of extracellular vesicles (EVs) and residual cells (RCs). Fifty hospitalized COVID-19 patients stratified by their D-dimer levels into high (>1.5 mg/L, n = 15) or low (≤1.5 mg/l, n = 35) and 10 healthy controls were assessed for medium-sized EVs (mEVs; 200-1000 nm) and large EVs/RCs (1000-4000 nm) by high sensitivity flow cytometry. EVs were analyzed for CD61, CD235a, CD45, and CD31, commonly used to detect platelets, red blood cells, leukocytes or endothelial cells, respectively, whilst phosphatidyl serine EVs/RCs were detected by lactadherin-binding implicating procoagulant catalytic surface. Small EV detection (sEVs; 50-200 nm) and CD41a (platelet integrin) colocalization with general EV markers CD9, CD63, and CD81 were performed by single particle interferometric reflectance imaging sensor. Patients with increased D-dimer exhibited the highest number of RCs and sEVs irrespective of cell origin (p < .05). Platelet activation, reflected by increased CD61+ and lactadherin+ mEV and RC levels, associated with coagulation disturbances. Patients with low D-dimer could be discriminated from controls by tetraspanin signatures of the CD41a+ sEVs, suggesting the changes in the circulating platelet sEV subpopulations may offer added prognostic value during COVID progression.

TGF-β regulates the release of breast cancer cell-derived extracellular vesicles and the sorting of their protein cargo by downregulating RAB27B expression

Extracellular vesicles (EVs) are important mediators of intercellular communication in the tumour microenvironment. The cytokine transforming growth factor-β (TGF-β) facilitates cancer progression via EVs secreted by cancer cells, which act on recipient cells in the tumour microenvironment. However, the mechanisms of how TGF-β affects cancer cell EV release and composition are incompletely understood. Here, we systematically investigate the effects of TGF-β on the release and protein composition of EVs from breast cancer cells. TGF-β suppresses the transcription of RAB27B mediated by SMAD3 and thereby hampers EV release. Using click chemistry and quantitative proteomics, we found that TGF-β increases the quantity of protein cargo and changes the composition of EVs by downregulating RAB27B expression. The recomposed EVs, induced by TGF-β or RAB27B depletion, inhibit CD8+ T cell-mediated breast cancer killing. Our findings reveal the critical roles of TGF-β and RAB27B in cancer development by regulating EV release and composition and thus provide potential targets to improve cancer immunotherapy.

Extracellular Vesicles from a Novel Chordoma Cell Line, ARF-8, Promote Tumorigenic Microenvironmental Changes When Incubated with the Parental Cells and with Human Osteoblasts

Chordomas are rare, generally slow-growing spinal tumors that nonetheless exhibit progressive characteristics over time, leading to malignant phenotypes and high recurrence rates, despite maximal therapeutic interventions. The tumors are notoriously resistant to therapies and are often located in regions that complicate achieving gross total resections. Cell lines from these tumors are rare as well. We cultured a new chordoma cell line (ARF-8) derived from an extensive clival chordoma that extended back to the cervical spine. We characterized the ARF-8 cellular and extracellular vesicle (EV) proteomes, as well as the impacts of ARF-8 EVs on the proteomes and secretomes of recipient cells (both ARF-8 and human osteoblasts) in autocrine and paracrine settings. Our proteomic analyses suggested roles for transforming growth factor beta (TGFB/TGFβ), cell-matrix interactions involving the epithelial-to-mesenchymal transition (EMT), and cell-extracellular matrix interactions in cell migration, consistent with a migratory/metastatic tumor phenotype. We demonstrated that ARF-8 tumor cell migration was dependent on general (arginine-glycine-aspartic acid [RGD]-based) integrin activity and that ARF-8 EVs could promote such migration. ARF-8 EVs also prompted proteomic/secretomic changes in human osteoblast cells, again with indications that cell-cell and cell-extracellular matrix interactions would be activated. All the characteristics typically associated with chordomas as cancers-migration and invasion, therapeutic resistance, metastatic potential-can be driven by tumor EVs. Overall, ARF-8 EVs promoted predicted tumorigenic phenotypes in recipient cells and suggested novel therapeutic targets for chordomas.

Mapping bacterial extracellular vesicle research: insights, best practices and knowledge gaps

Bacterial extracellular vesicles (BEVs) enable communication between bacteria and their natural habitats, including multicellular organisms such as humans. Consequently, the study of BEVs has rapidly gained attention with recent research raising the prospect of developing BEVs as biomarkers and treatments to manage (mal)functioning of natural habitats. Although diverse technologies are available, the composition of their source, their heterogeneity in biophysical and biochemical features, and their multifaceted cargo composition challenges the analysis of BEVs. To map current practices in BEV research, we analyzed 845 publications released in 2015-2021, reporting 3338 BEV-related experiments. The extracted data are accessible via the publicly available EV-TRACK knowledgebase ( https://evtrack.org/ ). We identify the need for transparent reporting, delineate knowledge gaps, outline available best practices and define areas in need of guidance to ensure advances in BEV research and accelerate BEV applications.

Simultaneous Protein and RNA Analysis in Single Extracellular Vesicles, Including Viruses

The individual detection of human immunodeficiency virus (HIV) virions and resolution from extracellular vesicles (EVs) during analysis is a difficult challenge. Infectious enveloped virions and nonviral EVs are released simultaneously by HIV-infected host cells, in addition to hybrid viral EVs containing combinations of HIV and host components but lacking replicative ability. Complicating the issue, EVs and enveloped virions are both delimited by a lipid bilayer and share similar size and density. The feature that distinguishes infectious virions from host and hybrid EVs is the HIV genomic RNA (gRNA), which allows the virus to replicate. Single-particle analysis techniques, which provide snapshots of single biological nanoparticles, could resolve infectious virions from EVs. However, current single-particle analysis techniques focus mainly on protein detection, which fail to resolve hybrid EVs from infectious virions. A method to simultaneously detect viral protein and internal gRNA in the same particle would allow resolution of infectious HIV from EVs and noninfectious virions. Here, we introduce SPIRFISH, a high-throughput method for single-particle protein and RNA analysis, combining single particle interferometric reflectance imaging sensor with single-molecule fluorescence in situ hybridization. Using SPIRFISH, we detect HIV-1 envelope protein gp120 and genomic RNA within single infectious virions, allowing resolution against EV background and noninfectious virions. We further show that SPIRFISH can be used to detect specific RNAs within EVs. This may have major utility for EV therapeutics, which are increasingly focused on EV-mediated RNA delivery. SPIRFISH should enable single particle analysis of a broad class of RNA-containing nanoparticles.

Size photometry and fluorescence imaging of immobilized immersed extracellular vesicles

Immunofluorescence analysis of individual extracellular vesicles (EVs) in common fluorescence microscopes is gaining popularity due to its accessibility and high fluorescence sensitivity; however, EV number and size are only measurable using fluorescent stains requiring extensive sample manipulations. Here we introduce highly sensitive label-free EV size photometry (SP) based on interferometric scattering (iSCAT) imaging of immersed EVs immobilized on a glass coverslip. We implement SP on a common inverted epifluorescence microscope with LED illumination and a simple 50:50 beamsplitter, permitting seamless integration of SP with fluorescence imaging (SPFI). We present a high-throughput SPFI workflow recording >10,000 EVs in 7 min over ten 88 × 88 µm2 fields of view, pre- and post-incubation imaging to suppress background, along with automated image alignment, aberration correction, spot detection and EV sizing. We achieve an EV sizing range from 37 to ∼220 nm in diameter with a dual 440 and 740 nm SP illumination scheme, and suggest that this range can be extended by more advanced image analysis or additional hardware customization. We benchmark SP to flow cytometry using calibrated silica nanoparticles and demonstrate superior, label-free sensitivity. We showcase SPFI's potential for EV analysis by experimentally distinguishing surface and volumetric EV dyes, observing the deformation of EVs adsorbed to a surface, and by uncovering distinct subpopulations in <100 nm-in-diameter EVs with fluorescently tagged membrane proteins.

Beyond basic characterization and omics: Immunomodulatory roles of platelet-derived extracellular vesicles unveiled by functional testing

Renowned for their role in haemostasis and thrombosis, platelets are also increasingly recognized for their contribution in innate immunity, immunothrombosis and inflammatory diseases. Platelets express a wide range of receptors, which allows them to reach a variety of activation endpoints and grants them immunomodulatory functions. Activated platelets release extracellular vesicles (PEVs), whose formation and molecular cargo has been shown to depend on receptor-mediated activation and environmental cues. This study compared the immunomodulatory profiles of PEVs generated via activation of platelets by different receptors, glycoprotein VI, C-type lectin-like receptor 2 and combining all thrombin-collagen receptors. Functional assays in vivo in zebrafish and in vitro in human macrophages highlighted distinct homing and secretory responses triggered by the PEVs. In contrast, omics analyses of protein and miRNA cargo combined with physicochemical particle characterization found only subtle differences between the activated PEV types, which were insufficient to predict their different immunomodulatory functions. In contrast, constitutively released PEVs, formed in the absence of an exogenous activator, displayed a distinct immunomodulatory profile from the receptor-induced PEVs. Our findings underscore that PEVs are tunable through receptor-mediated activation. To truly comprehend their role(s) in mediating platelet functions among immune cells, conducting functional assays is imperative.

Engineered plant-derived extracellular vesicles for targeted regulation and treatment of colitis-associated inflammation

Rationale: Inflammatory bowel disease (IBD) is a chronic disorder characterized by persistent inflammation of the gastrointestinal tract. Due to the elusive causes and complex mechanisms of this disorder, the development of highly effective therapeutic drugs is crucial. Extracellular vesicles (EVs) are small membrane-bound structures released by cells into the surrounding environment. Recent research has witnessed a substantial surge in the utilization of plant-derived EVs that offer advantages such as high productivity, low production costs, diverse biological functions, and low cytotoxicity. Herein, Red cabbage-derived EVs (Rabex) were investigated and engineered as potential therapeutic agents for IBD. Methods: Rabex was engineered by surface conjugation with hyaluronic acid (t-Rabex) to simultaneously enhance the targeting of intestinal epithelial and immune cells, thereby improving their therapeutic targeting and efficacy. The properties and therapeutic potential of t-Rabex were assessed through both in vitro studies and in vivo experiments, focusing on their capacity to reach the gastrointestinal tract and exert a therapeutic effect compared to unmodified Rabex. Results: Rabex exhibited dual functions, including the suppression of inflammation in macrophages and promotion of colon epithelial cell regeneration, both of which are critical for effective IBD treatment. In vitro and in vivo studies of t-Rabex have demonstrated its superior targeting efficiency to the gastrointestinal tract and therapeutic efficacy compared to Rabex, making it a promising and more effective IBD treatment. Understanding the mechanism of action of t-Rabex in colonic tissues highlighted its anti-inflammatory, antioxidative, and tight-junction maintenance properties. Conclusions: These findings underscore the potential of t-Rabex as a precise therapeutic agent for IBD and shed light on the diverse applications of plant-derived EVs.

Simultaneous detection of membrane protein and mRNA at single extracellular vesicle level by droplet microfluidics for cancer diagnosis

INTRODUCTION

Simultaneous detection of proteins and mRNA within a single extracellular vesicle (EV) enables comprehensive analysis of specific EVs subpopulations, significantly advancing cancer diagnostics. However, developing a sensitive and user-friendly approach for simultaneously detecting multidimensional biomarkers in single EV is still challenging.

OBJECTIVES

To facilitate the analysis of multidimensional biomarkers in EVs and boost its clinical application, we present a versatile droplet digital system facilitating the concurrent detection of membrane proteins and mRNA at the single EV level with high sensitivity and specificity.

METHODS

The antibody-DNA conjugates were firstly prepared for EVs protein biomarkers recognition and signal transformation. Coupling with the assembled triplex droplet digital PCR system, a versatile droplet digital analysis assay for simultaneous detection of membrane protein and mRNA at a single EV level was developed.

RESULTS

Our new droplet digital system displayed high sensitivity and specificity. Additionally, its clinical application was validated in a breast cancer cohort. As expected, this assay has demonstrated superior performance in distinguishing breast cancer from healthy individuals and benign controls through combined detection of EVs protein and mRNA markers compared to any single kind marker detections, especially for patients with breast cancer at early stage (AUC=0.9229).

CONCLUSION

Consequently, this study proposes a promising strategy for accurately identifying and analyzing specific EV subgroups through the co-detection of proteins and mRNA at the single EV level, holding significant potential for future clinical applications.

Unveiling potential: urinary exosomal mRNAs as non-invasive biomarkers for early prostate cancer diagnosis

BACKGROUND

This study investigated the use of urinary exosomal mRNA as a potential biomarker for the early detection of prostate cancer (PCa).

METHODS

Next-generation sequencing was utilized to analyze exosomal RNA from 10 individuals with confirmed PCa and 10 individuals without cancer. Subsequent validation through qRT-PCR in a larger sample of 43 PCa patients and 92 healthy controls revealed distinct mRNA signatures associated with PCa.

RESULTS

Notably, mRNAs for RAB5B, WWP1, HIST2H2BF, ZFY, MARK2, PASK, RBM10, and NRSN2 showed promise as diagnostic markers, with AUC values between 0.799 and 0.906 and significance p values. Combining RAB5B and WWP1 in an exoRNA diagnostic model outperformed traditional PSA tests, achieving an AUC of 0.923, 81.4% sensitivity, and 89.1% specificity.

CONCLUSIONS

These findings highlight the potential of urinary exosomal mRNA profiling, particularly focusing on RAB5B and WWP1, as a valuable strategy for improving the early detection of PCa.

Measuring Concentration of Nanoparticles in Polydisperse Mixtures Using Interferometric Nanoparticle Tracking Analysis

Quantitative measurements of nanoparticle concentration in liquid suspensions are in high demand, for example, in the medical and food industries. Conventional methods remain unsatisfactory, especially for polydisperse samples with overlapping size ranges. Recently, we introduced interferometric nanoparticle tracking analysis (iNTA) for high-precision measurement of nanoparticle size and refractive index. Here, we show that by counting the number of trajectories that cross the focal plane, iNTA can measure concentrations of subpopulations in a polydisperse mixture in a quantitative manner and without the need for a calibration sample. We evaluate our method on both monodisperse samples and mixtures of known concentrations. Furthermore, we assess the concentration of SARS-CoV-2 in supernatant samples obtained from infected cells.

Cryogenic electron microscopy reveals morphologically distinct subtypes of extracellular vesicles among porcine ejaculate fractions

Seminal plasma (SP) is rich in extracellular vesicles (EVs), which are still poorly studied, especially in livestock species. To better understand their functional role in both spermatozoa and endometrial epithelial cells, proper characterization of EVs is an essential step. The objective was to phenotypically characterize porcine seminal EVs (sEVs) using cryogenic electron microscopy (cryo-EM), which allows visualization of EVs in their native state. Porcine ejaculates are released in fractions, each containing SP from different source. This allows characterization sEVs released from various male reproductive tissues. Two experiments were performed, the first with SP from the entire ejaculate (n:6) and the second with SP from three ejaculate fractions (n:15): the first 10 mL of the sperm-rich ejaculate fraction (SRF-P1) with SP mainly from the epididymis, the remainder of the SRF (SRF-P2) with SP mainly from the prostate, and the post-SRF with SP mainly from the seminal vesicles. The sEVs were isolated by size exclusion chromatography and 1840 cryo-EM sEV images were acquired using a Jeol-JEM-2200FS/CR-EM. The size, electron density, complexity, and peripheral corona layer were measured in each sEV using the ImageJ software. The first experiment showed that sEVs were structurally and morphologically heterogeneous, although most (83.1%) were small (less than 200 nm), rounded, and poorly electrodense, and some have a peripheral coronal layer. There were also larger sEVs (16.9%) that were irregularly shaped, more electrodense, and few with a peripheral coronal layer. The second experiment showed that small sEVs were more common in SRF-P1 and SRF-P2, indicating that they originated mainly from the epididymis and prostate. Large sEVs were more abundant in post-SRF, indicating that they originated mainly from seminal vesicles. Porcine sEVs are structurally and morphologically heterogeneous. This would be explained by the diversity of reproductive organs of origin.

An electro-optical platform for the ultrasensitive detection of small extracellular vesicle sub-types and their protein epitope counts

Methods for detecting proteins in small extracellular vesicles (sEVs) lack sensitivity and quantitative accuracy, missing clues about health and disease. Our study introduces the Nano-Extracellular Omics Sensing (NEXOS) platform, merging electrical (E-NEXOS) and optical detection (O-NEXOS). E-NEXOS determines the concentration of target sEV sub-types, and O-NEXOS quantifies the concentration of target protein epitopes (TEPs) on those TEVs. In this work, both technologies were compared to several sEV detection tools, showing superior detection limits for CD9+CD81+ and CD9+HER2+ sEVs. Furthermore, the additional information on TEVs and TEPs from bulk sEV samples, provided new phenotyping capabilities. We determined the average number of CD81 and HER2 proteins on CD9+ sEVs, a number which was later validated on spiked human plasma. These results highlight the compatibility of NEXOS with complex biofluids and, as importantly, hint at its many potential applications, ranging from basic research to the anticipated clinical translation of sEVs.

RNA Landscapes of Brain and Brain-Derived Extracellular Vesicles in Simian Immunodeficiency Virus Infection and Central Nervous System Pathology

BACKGROUND

Brain tissue-derived extracellular vesicles (bdEVs) act locally in the central nervous system (CNS) and may indicate molecular mechanisms in human immunodeficiency virus (HIV) CNS pathology. Using brain homogenate (BH) and bdEVs from a simian immunodeficiency virus (SIV) model of HIV disease, we identified RNA networks in SIV infection and neuroinflammation.

METHODS

Postmortem occipital cortex samples were obtained from uninfected controls and SIV-infected subjects (acute and chronic phases with or without CNS pathology [SIV encephalitis]). bdEVs were separated and characterized per international consensus guidelines. RNAs from bdEVs and BH were sequenced and quantitative polymerase chain reaction (qPCR)-amplified to detect levels of small RNAs (sRNAs, including microRNAs [miRNAs]) and longer RNAs including messenger RNAs (mRNAs) and circular RNAs (circRNAs).

RESULTS

Dysregulated RNAs in BH and bdEVs were identified in acute and chronic infection with pathology groups, including mRNAs, miRNAs, and circRNAs. Most dysregulated mRNAs in bdEVs reflected dysregulation in source BH. These mRNAs are disproportionately involved in inflammation and immune responses. Based on target prediction, several circRNAs that were differentially abundant in source tissue might be responsible for specific differences in sRNA levels in bdEVs during SIV infection.

CONCLUSIONS

RNA profiling of bdEVs and source tissues reveals potential regulatory networks in SIV infection and SIV-related CNS pathology.

Critical parameters to standardize the size and concentration determination of nanomaterials by nanoparticle tracking analysis

The size and concentration are critical for the diagnostic and therapeutic applications of nanomaterials but the accurate measurement remains challenging. Nanoparticle tracking analysis (NTA) is widely used for size and concentration determination. However, highly repeatable standard operating procedures (SOPs) are absent. We adopted the "search-evaluate-test" strategy to standardize the measurement by searching the critical parameters. The particles per frame are linearly proportional to the sample concentration and the measured results are more accurate and repeatable when the concentration is 108-109 particles/ml. The optimal detection threshold is around 5. The optimal camera level is such that it allows clear observation of particles without diffractive rings and overexposure. The optimal speed is ≤ 50 in AU and ∼ 10 μl/min in flow rate. We then evaluated the protocol using polydisperse polystyrene particles and we found that NTA could discriminate particles in bimodal mixtures with high size resolution but the performance on multimodal mixtures is not as good as that of resistive pulse sensing (RPS). We further analyzed the polystyrene particles, SiO2 particles, and biological samples by NTA following the SOPs. The size and concentration measured by NTA differentially varies to those determined by RPS and transmission electron microscopy.

Microorganism-derived extracellular vesicles: emerging contributors to female reproductive health

Extracellular vesicles (EVs) are cell-derived nanoparticles that carry small molecules, nucleic acids, and proteins long distances in the body facilitating cell-cell communication. Microorganism-derived EVs mediate communication between parent cells and host cells, with recent evidence supporting their role in biofilm formation, horizontal gene transfer, and suppression of the host immune system. As lipid-bound bacterial byproducts, EVs demonstrate improved cellular uptake and distribution in vivo compared to cell-free nucleic acids, proteins, or small molecules, allowing these biological nanoparticles to recapitulate the effects of parent cells and contribute to a range of human health outcomes. Here, we focus on how EVs derived from vaginal microorganisms contribute to gynecologic and obstetric outcomes. As the composition of the vaginal microbiome significantly impacts women's health, we discuss bacterial EVs from both healthy and dysbiotic vaginal microbiota. We also examine recent work done to evaluate the role of EVs from common vaginal bacterial, fungal, and parasitic pathogens in pathogenesis of female reproductive tract disease. We highlight evidence for the role of EVs in women's health, gaps in current knowledge, and opportunities for future work. Finally, we discuss how leveraging the innate interactions between microorganisms and mammalian cells may establish EVs as a novel therapeutic modality for gynecologic and obstetric indications.

One-step and label-free ratiometric fluorescence assay for the detection of plasma exosome towards cancer diagnosis

Exosomes are closely associated with tumor development and are regarded as viable biomarkers for cancer. Here, a ratiometric fluorescence method was proposed for the one-step and label-free detection of plasma exosomes. A bicolor streptavidin magnetic beads were specifically created with an immobilized Cy5-labeled hairpin aptamer for CD63 (Cy5-Apt) on its surface to identify exosome, and a green color SYBR Green I (SGI) embedded in the stem of Cy5-Apt to respond to exosomes. After exosome capture, the Cy5-Apt could undergo a conformational shift and release the encapsulated SGI, allowing exosome measurement based on the fluorescence ratio of Cy5 and SGI. The enrichment, separation and detection of exosomes in proposed method could be completed in one step (30 min), which is a significant improvement over previous method. Furthermore, the use of ratiometric fluorescence and magnetic separation allows for exosome enrichment and interference elimination from complex matrices, improving accuracy and sensitivity. Particularly, the assay could detect exosomes in plasma and has potential to distinguish lung cancer patients from healthy volunteers with an area under the receiver operator characteristic curve of 0.85. Besides, the study provided an efficient method for analyzing the various divisions of exosomes by merely modifying the aptamer, which holds great promise for point-of-care applications.

Engineered PDGFA-ligand-modified exosomes delivery T3 for demyelinating disease targeted therapy

Demyelination is a proper syndrome in plenty of central nervous system (CNS) diseases, which is the main obstacle to recovery and still lacks an effective treatment. To overcome the limitations of the brain-blood barrier on drug permeability, we modified an exosome secreted by neural stem cells (NSCs), which had transfected with lentivirus armed with platelet-derived growth factors A (PDGFA)-ligand. Through the in vivo and in vitro exosomes targeting test, the migration ability to the lesion areas and OPCs significantly improved after ligand modification. Furthermore, the targeted exosomes loaded with 3,5, 30-L-triiodothyronine (T3) have a critical myelination ability in CNS development, administrated to the cuprizone animal model treatment. The data shows that the novel drug vector loaded with T3 significantly promotes remyelination compared with T3 alone. At the same time, it improved the CNS microenvironment by reducing astrogliosis, inhibiting pro-inflammatory microglia, and alleviating axon damage. This investigation provides a straightforward strategy to produce a targeting exosome and indicates a possible therapeutic manner for demyelinating disease.

ESBL-Escherichia coli extracellular vesicles mediate bacterial resistance to β-lactam and mediate horizontal transfer of blaCTX-M-55

OBJECTIVES

Extracellular vesicles (EVs) have become the focus of research as an emerging method of horizontal gene transfer. In recent years, studies on the association between EVs and the spread of bacterial resistance have emerged, but there is a lack of research on the role of EVs secreted by extended-spectrum β-lactamase (ESBL)-producing Escherichia coli in the spread of β-lactam resistance. Therefore, the aim of this study was to investigate the role of EVs in the transmission of β-lactam resistance.

METHODS

In this study, the role of EVs in the transmission of β-lactam resistance in E. coli was evaluated by the EVs-mediated bacterial resistance to β-lactam antibiotics test and the EVs-mediated blaCTX-M-55 transfer experiments using EVs secreted by ESBL-E. coli.

RESULTS

The results showed that ESBL-EVs were protective against β-lactam antibiotic-susceptible bacteria, and this protective effect was dependent on the integrity of the EVs and showed dose- and time-dependent effects. At the same time, ESBL-EVs can also mediate the horizontal transmission of blaCTX-M-55, and EVs-mediated gene transfer is selective, preferring to transfer in more closely related species.

CONCLUSIONS

In this study, we demonstrated the important role of EVs in the transmission of β-lactam resistance in chicken ESBL-E. coli, and evaluated the risk of EVs-mediated horizontal gene transfer, which provided a theoretical basis for elucidating the mechanism of EVs-mediated resistance transmission.

Harnessing Bacterial Extracellular Vesicle Immune Effects for Cancer Therapy

There are a growing number of studies linking the composition of the human microbiome to disease states and treatment responses, especially in the context of cancer. This has raised significant interest in developing microbes and microbial products as cancer immunotherapeutics that mimic or recapitulate the beneficial effects of host-microbe interactions. Bacterial extracellular vesicles (bEVs) are nano-sized, membrane-bound particles secreted by essentially all bacteria species and contain a diverse bioactive cargo of the producing cell. They have a fundamental role in facilitating interactions among cells of the same species, different microbial species, and even with multicellular host organisms in the context of colonization (microbiome) and infection. The interaction of bEVs with the immune system has been studied extensively in the context of infection and suggests that bEV effects depend largely on the producing species. They thus provide functional diversity, while also being nonreplicative, having inherent cell-targeting qualities, and potentially overcoming natural barriers. These characteristics make them highly appealing for development as cancer immunotherapeutics. Both natively secreted and engineered bEVs are now being investigated for their application as immunotherapeutics, vaccines, drug delivery vehicles, and combinations of the above, with promising early results. This suggests that both the intrinsic immunomodulatory properties of bEVs and their ability to be modified could be harnessed for the development of next-generation microbe-inspired therapies. Nonetheless, there remain major outstanding questions regarding how the observed preclinical effectiveness will translate from murine models to primates, and humans in particular. Moreover, research into the pharmacology, toxicology, and mass manufacturing of this potential novel therapeutic platform is still at early stages. In this review, we highlight the breadth of bEV interactions with host cells, focusing on immunologic effects as the main mechanism of action of bEVs currently in preclinical development. We review the literature on ongoing efforts to develop natively secreted and engineered bEVs from a variety of bacterial species for cancer therapy and finally discuss efforts to overcome outstanding challenges that remain for clinical translation.

Spinning with exosomes: electrospun nanofibers for efficient targeting of stem cell-derived exosomes in tissue regeneration

Electrospinning technique converts polymeric solutions into nanoscale fibers using an electric field and can be used for various biomedical and clinical applications. Extracellular vesicles (EVs) are cell-derived small lipid vesicles enriched with biological cargo (proteins and nucleic acids) potential therapeutic applications. In this review, we discuss extending the scope of electrospinning by incorporating stem cell-derived EVs, particularly exosomes, into nanofibers for their effective delivery to target tissues. The parameters used during the electrospinning of biopolymers limit the stability and functional properties of cellular products. However, with careful consideration of process requirements, these can significantly improve stability, leading to longevity, effectiveness, and sustained and localized release. Electrospun nanofibers are known to encapsulate or surface-adsorb biological payloads such as therapeutic EVs, proteins, enzymes, and nucleic acids. Small EVs, specifically exosomes, have recently attracted the attention of researchers working on regeneration and tissue engineering because of their broad distribution and enormous potential as therapeutic agents. This review focuses on current developments in nanofibers for delivering therapeutic cargo molecules, with a special emphasis on exosomes. It also suggests prospective approaches that can be adapted to safely combine these two nanoscale systems and exponentially enhance their benefits in tissue engineering, medical device coating, and drug delivery applications.

Novel multiparametric bulk and single EV pipeline for adipose cell-specific biomarker discovery in paired human biospecimens

Obesity is a global health crisis that contributes to morbidity and mortality worldwide. Obesity's comorbid association with a variety of diseases, from metabolic syndrome to neurodegenerative disease, underscores the critical need to better understand the pathobiology of obesity. Adipose tissue, once seen as an inert storage depot, is now recognized as an active endocrine organ, regulating metabolic and systemic homeostasis. Recent studies spotlight the theranostic utility of extracellular vesicles (EVs) as novel biomarkers and drivers of disease, including obesity-related complications. Adipose-derived EVs (ADEVs) have garnered increased interest for their roles in diverse diseases, however robust isolation and characterization protocols for human, cell-specific EV subsets are limited. Herein, we directly address this technical challenge by establishing a multiparametric analysis framework that leverages bulk and single EV characterization, mRNA phenotyping and proteomics of human ADEVs directly from paired visceral adipose tissue, cultured mature adipocyte conditioned media, and plasma from obese subjects undergoing bariatric surgery. Importantly, rigorous EV phenotyping at the tissue and cell-specific level identified top 'adipose liquid biopsy' candidates that were validated in circulating plasma EVs from the same patient. In summary, our study paves the way toward a tissue and cell-specific, multiparametric framework for studying tissue and circulating adipose EVs in obesity-driven disease.

Approaches to Characterize and Quantify Extracellular Vesicle Surface Conjugation Efficiency

Extracellular vesicles (EVs) are cell-secreted nanovesicles that play an important role in long-range cell-cell communication. Although EVs pose a promising alternative to cell-based therapy, targeted in vivo delivery still falls short. Many studies have explored the surface modification of EVs to enhance their targeting capabilities. However, to our knowledge, there are no standardized practices to confirm the successful surface modification of EVs or calculate the degree of conjugation on EV surfaces (conjugation efficiency). These pieces of information are essential in the reproducibility of targeted EV therapeutics and the determination of optimized conjugation conditions for EVs to see significant therapeutic effects in vitro and in vivo. This review will discuss the vast array of techniques adopted, technologies developed, and efficiency definitions made by studies that have calculated EV/nanoparticle surface conjugation efficiency and how differences between studies may contribute to differently reported conjugation efficiencies.

Manufacturing, quality control, and GLP-grade preclinical study of nebulized allogenic adipose mesenchymal stromal cells-derived extracellular vesicles

BACKGROUND

Human adipose stromal cells-derived extracellular vesicles (haMSC-EVs) have been shown to alleviate inflammation in acute lung injury (ALI) animal models. However, there are few systemic studies on clinical-grade haMSC-EVs. Our study aimed to investigate the manufacturing, quality control (QC) and preclinical safety of clinical-grade haMSC-EVs.

METHODS

haMSC-EVs were isolated from the conditioned medium of human adipose MSCs incubated in 2D containers. Purification was performed by PEG precipitation and differential centrifugation. Characterizations were conducted by nanoparticle tracking analysis, transmission electron microscopy (TEM), Western blotting, nanoflow cytometry analysis, and the TNF-α inhibition ratio of macrophage [after stimulated by lipopolysaccharide (LPS)]. RNA-seq and proteomic analysis with liquid chromatography tandem mass spectrometry (LC-MS/MS) were used to inspect the lot-to-lot consistency of the EV products. Repeated toxicity was evaluated in rats after administration using trace liquid endotracheal nebulizers for 28 days, and respiratory toxicity was evaluated 24 h after the first administration. In vivo therapeutic effects were assessed in an LPS-induced ALI/ acute respiratory distress syndrome (ARDS) rat model.

RESULTS

The quality criteria have been standardized. In a stability study, haMSC-EVs were found to remain stable after 6 months of storage at - 80°C, 3 months at - 20 °C, and 6 h at room temperature. The microRNA profile and proteome of haMSC-EVs demonstrated suitable lot-to-lot consistency, further suggesting the stability of the production processes. Intratracheally administered 1.5 × 108 particles/rat/day for four weeks elicited no significant toxicity in rats. In LPS-induced ALI/ARDS model rats, intratracheally administered haMSC-EVs alleviated lung injury, possibly by reducing the serum level of inflammatory factors.

CONCLUSION

haMSC-EVs, as an off-shelf drug, have suitable stability and lot-to-lot consistency. Intratracheally administered haMSC-EVs demonstrated excellent safety at the tested dosages in systematic preclinical toxicity studies. Intratracheally administered haMSC-EVs improved the lung function and exerted anti-inflammatory effects on LPS-induced ALI/ARDS model rats.

Micro Trojan horses: Engineering extracellular vesicles crossing biological barriers for drug delivery

The biological barriers of the body, such as the blood-brain, placental, intestinal, skin, and air-blood, protect against invading viruses and bacteria while providing necessary physical support. However, these barriers also hinder the delivery of drugs to target tissues, reducing their therapeutic efficacy. Extracellular vesicles (EVs), nanostructures with a diameter ranging from 30 nm to 10 μm secreted by cells, offer a potential solution to this challenge. These natural vesicles can effectively pass through various biological barriers, facilitating intercellular communication. As a result, artificially engineered EVs that mimic or are superior to the natural ones have emerged as a promising drug delivery vehicle, capable of delivering drugs to almost any body part to treat various diseases. This review first provides an overview of the formation and cross-species uptake of natural EVs from different organisms, including animals, plants, and bacteria. Later, it explores the current clinical applications, perspectives, and challenges associated with using engineered EVs as a drug delivery platform. Finally, it aims to inspire further research to help bioengineered EVs effectively cross biological barriers to treat diseases.

Maternal preconception stress produces sex-specific effects at the maternal:fetal interface to impact offspring development and phenotypic outcomes†

Entering pregnancy with a history of adversity, including adverse childhood experiences and racial discrimination stress, is a predictor of negative maternal and fetal health outcomes. Little is known about the biological mechanisms by which preconception adverse experiences are stored and impact future offspring health outcomes. In our maternal preconception stress (MPS) model, female mice underwent chronic stress from postnatal days 28-70 and were mated 2 weeks post-stress. Maternal preconception stress dams blunted the pregnancy-induced shift in the circulating extracellular vesicle proteome and reduced glucose tolerance at mid-gestation, suggesting a shift in pregnancy adaptation. To investigate MPS effects at the maternal:fetal interface, we probed the mid-gestation placental, uterine, and fetal brain tissue transcriptome. Male and female placentas differentially regulated expression of genes involved in growth and metabolic signaling in response to gestation in an MPS dam. We also report novel offspring sex- and MPS-specific responses in the uterine tissue apposing these placentas. In the fetal compartment, MPS female offspring reduced expression of neurodevelopmental genes. Using a ribosome-tagging transgenic approach we detected a dramatic increase in genes involved in chromatin regulation in a PVN-enriched neuronal population in females at PN21. While MPS had an additive effect on high-fat-diet (HFD)-induced weight gain in male offspring, both MPS and HFD were necessary to induce significant weight gain in female offspring. These data highlight the preconception period as a determinant of maternal health in pregnancy and provides novel insights into mechanisms by which maternal stress history impacts offspring developmental programming.

Engineered Extracellular Vesicles in Wound Healing: Design, Paradigms, and Clinical Application

The severe quality of life and economic burden imposed by non-healing skin wounds, infection risks, and treatment costs are affecting millions of patients worldwide. To mitigate these challenges, scientists are relentlessly seeking effective treatment measures. In recent years, extracellular vesicles (EVs) have emerged as a promising cell-free therapy strategy, attracting extensive attention from researchers. EVs mediate intercellular communication, possessing excellent biocompatibility and stability. These features make EVs a potential tool for treating a plethora of diseases, including those related to wound repair. However, there is a growing focus on the engineering of EVs to overcome inherent limitations such as low production, relatively fixed content, and targeting capabilities of natural EVs. This engineering could improve both the effectiveness and specificity of EVs in wound repair treatments. In light of this, the present review will introduce the latest progress in the design methods and experimental paradigms of engineered EVs applied in wound repair. Furthermore, it will comprehensively analyze the current clinical research status and prospects of engineered EVs within this field.

Minimal information for studies of extracellular vesicles (MISEV2023): From basic to advanced approaches

Extracellular vesicles (EVs), through their complex cargo, can reflect the state of their cell of origin and change the functions and phenotypes of other cells. These features indicate strong biomarker and therapeutic potential and have generated broad interest, as evidenced by the steady year-on-year increase in the numbers of scientific publications about EVs. Important advances have been made in EV metrology and in understanding and applying EV biology. However, hurdles remain to realising the potential of EVs in domains ranging from basic biology to clinical applications due to challenges in EV nomenclature, separation from non-vesicular extracellular particles, characterisation and functional studies. To address the challenges and opportunities in this rapidly evolving field, the International Society for Extracellular Vesicles (ISEV) updates its 'Minimal Information for Studies of Extracellular Vesicles', which was first published in 2014 and then in 2018 as MISEV2014 and MISEV2018, respectively. The goal of the current document, MISEV2023, is to provide researchers with an updated snapshot of available approaches and their advantages and limitations for production, separation and characterisation of EVs from multiple sources, including cell culture, body fluids and solid tissues. In addition to presenting the latest state of the art in basic principles of EV research, this document also covers advanced techniques and approaches that are currently expanding the boundaries of the field. MISEV2023 also includes new sections on EV release and uptake and a brief discussion of in vivo approaches to study EVs. Compiling feedback from ISEV expert task forces and more than 1000 researchers, this document conveys the current state of EV research to facilitate robust scientific discoveries and move the field forward even more rapidly.

Extracellular Vesicles as Liquid Biopsy Biomarkers across the Cancer Journey: From Early Detection to Recurrence

BACKGROUND

Cancer is a dynamic process and thus requires highly informative and reliable biomarkers to help guide patient care. Liquid-based biopsies have emerged as a clinical tool for tracking cancer dynamics. Extracellular vesicles (EVs), lipid bilayer delimited particles secreted by cells, are a new class of liquid-based biomarkers. EVs are rich in selectively sorted biomolecule cargos, which provide a spatiotemporal fingerprint of the cell of origin, including cancer cells.

CONTENT

This review summarizes the performance characteristics of EV-based biomarkers at different stages of cancer progression, from early malignancy to recurrence, while emphasizing their potential as diagnostic, prognostic, and screening biomarkers. We discuss the characteristics of effective biomarkers, consider challenges associated with the EV biomarker field, and report guidelines based on the biomarker discovery pipeline.

SUMMARY

Basic science and clinical trial studies have shown the potential of EVs as precision-based biomarkers for tracking cancer status, with promising applications for diagnosing disease, predicting response to therapy, and tracking disease burden. The multi-analyte cargos of EVs enhance the performance characteristics of biomarkers. Recent technological advances in ultrasensitive detection of EVs have shown promise with high specificity and sensitivity to differentiate early-cancer cases vs healthy individuals, potentially outperforming current gold-standard imaging-based cancer diagnosis. Ultimately, clinical translation will be dictated by how these new EV biomarker-based platforms perform in larger sample cohorts. Applying ultrasensitive, scalable, and reproducible EV detection platforms with better design considerations based upon the biomarker discovery pipeline should guide the field towards clinically useful liquid biopsy biomarkers.

Unraveling the surface marker signature of cell-derived vesicles via proteome analysis and nanoparticle flow cytometry

The cell-derived vesicles (CDVs) obtained using a proprietary extrusion process are the foundation of BioDrone platform technology. With superior productivity and versatility, this technology has garnered increasing attention in broad applications, particularly as a drug delivery vehicle. Previously, we showed that CDVs exhibited varying levels of expression for tetraspanin and organelle membrane markers while revealing no discernible differences in physical characteristics compared to naturally produced extracellular vesicles (EVs). To further understand and utilize the therapeutic potentials of CDVs, a more comprehensive study of membrane protein profiles is necessary. In addition, it is crucial to validate that the CDVs produced from extrusion are indeed intact lipid vesicles rather than other impurities. Here, we produced multiple batches of CDVs and EVs from HEK293 cells. CDVs and EVs were subjected to the same purification processes for subsequent proteome and particle analyses. The proteome analyses revealed unique proteome signatures between CDVs, EVs, and parental cells. Extensive proteome analyses identified the nine most prominent membrane markers that are abundant in CDVs compared to cells and EVs. Subsequent western blotting and nanoparticle flow cytometry analyses confirmed that CD63, lysosome-associated membrane glycoprotein 1 (LAMP1), and nicastrin (NCSTN) are highly enriched in CDVs, whereas CD81, CD9, and prostaglandin F2 receptor negative regulator (PTGFRN) are more abundant in EVs. This highlights the unique membrane composition and marker signature of CDVs that are distinct from EVs. Lastly, we demonstrated that more than 90% of the CDVs are genuine lipid vesicles by combining two different classes of vesicle labeling dyes and detergents to disrupt lipid membranes. This indicates that our proprietary extrusion technology is highly compatible with other well-characterized EV production methods. The robust CDV markers identified in this study will also facilitate the engineering of CDVs to achieve enhanced therapeutic effects or tissue-selective cargo delivery.

Dose Determination and Administration of Bacterial Extracellular Vesicles for In Vivo Preclinical Studies

Essentially all bacteria secrete nano-sized (~20-200 nm) bacterial extracellular vesicles (bEVs) loaded with proteins, lipids, glycans, and nucleic acids. bEVs facilitate interactions among cells of the same species, different microbial species, and even with cells of multicellular organisms in the context of colonization or infection. Their interactions with host organism immune cell receptors vary depending on the producing bacterial species and are now being harnessed for the development of bEVs as a potential immunotherapeutic platform. Both basic/mechanistic and preclinical therapeutic development studies are thus increasing in number and require implementation of methods for multiparametric analytical characterization as well as in vivo administration in preclinical animal models of disease. We summarize a variety of analytical methods that can be used to calculate bEV dose for preparations made from diverse bacterial sources (including sterility testing, total protein concentration, particle concentration, and lipopolysaccharide concentration). We also describe basic methodology for intravenous administration of bEV preparations via tail vein injection in laboratory mice. Throughout the description of methodology, we highlight potential pitfalls and alternatives to further equip the reader for troubleshooting should challenges arise. Robust and reproducible characterization is a prerequisite of bEV preparation quality control and consistent dosing during preclinical development. This will allow for more streamlined testing of candidate therapeutic bEVs within a given research laboratory, and furthermore facilitate reproducibility of findings across laboratories.

Multiple Particle Tracking: A Method for Probing Biologically Relevant Mobility of Bacterial Extracellular Vesicles

Bacterial extracellular vesicles (bEVs) are produced by both Gram-negative and Gram-positive bacteria. These biological nanoparticles transport small molecules, nucleic acids, and proteins, enabling communication with both bacterial and mammalian cells. bEVs can evade and disrupt biological barriers, and their lipid membranes protect their cargo from degradation, facilitating long-distance communication in vivo. Furthermore, bacteria are easily manipulated and easily cultured. These combined factors make bEVs an ideal candidate for drug delivery applications. Thus, the study of how bEVs interact with biological barriers is interesting from both a signaling and drug delivery perspective. Here we describe methods for tracking bEV motion in biological matrices ex vivo. We outline methods for growth, isolation, quantification, and labeling, as well as techniques for tracking bEV motion ex vivo and quantifying these data. The methods described here are relevant to bEV communication with host cells as well as drug delivery applications using bEVs.

Assessing Extracellular Vesicles in Human Biofluids Using Flow-Based Analyzers

Extracellular vesicles (EVs) are increasingly being analyzed by flow cytometry. Yet their minuscule size and low refractive index cause the scatter intensity of most EVs to fall below the detection limit of most flow cytometers. A new class of devices, known as spectral flow analyzers, are becoming standards in cell phenotyping studies, largely due to their unique capacity to detect a vast panel of markers with higher sensitivity for light scatter detection. Another class of devices, known as nano-analyzers, provides high-resolution detection of sub-micron-sized particles. Here, the EV phenotyping performance between the Aurora (Cytek) spectral cell analyzer and the NanoFCM (nFCM) nanoflow analyzer are compared. These two devices are specifically chosen given their lead in becoming gold standards in their respective fields. Immune cell-derived EVs remain poorly characterized despite their clinical potential. Therefore, B- and T-cell line-derived EVs and donor-matched human biofluid-derived EVs from plasma, urine, and saliva are used in combination with a panel of established immune markers for this comparative study. A comparative evaluation of both cytometry platforms is performed, discussing their potential and suitability for different applications. It is found that nFCM can accurately i) analyze small EVs (40-200 nm) matching the size accuracy of electron microscopy; ii) measure the concentration of a single EV particle per volume; iii) identify underrepresented EV marker subsets; and iv) provide co-localization of EV surface markers. It can also be shown that human sample biofluids have unique EV marker signatures that can have future clinical relevance. Finally, nFCM and Aurora have their unique strength, preferred fashion of data acquisition, and visualization to fit different research interests.

An ex vivo model of interactions between extracellular vesicles and peripheral mononuclear blood cells in whole blood

Extracellular vesicles (EVs) can be loaded with therapeutic cargo and engineered for retention by specific body sites; therefore, they have great potential for targeted delivery of biomolecules to treat diseases. However, the pharmacokinetics and biodistribution of EVs in large animals remain relatively unknown, especially in primates. We recently reported that when cell culture-derived EVs are administered intravenously to Macaca nemestrina (pig-tailed macaques), they differentially associate with specific subsets of peripheral blood mononuclear cells (PBMCs). More than 60% of CD20+ B cells were observed to associate with EVs for up to 1 h post-intravenous administration. To investigate these associations further, we developed an ex vivo model of whole blood collected from healthy pig-tailed macaques. Using this ex vivo system, we found that labelled EVs preferentially associate with B cells in whole blood at levels similar to those detected in vivo. This study demonstrates that ex vivo blood can be used to study EV-blood cell interactions.

Extracellular Vesicles and Their Renin-Angiotensin Cargo as a Link between Metabolic Syndrome and Parkinson's Disease

Several studies showed an association between metabolic syndrome (MetS) and Parkinson's disease (PD). The linking mechanisms remain unclear. MetS promotes low-grade peripheral oxidative stress and inflammation and dysregulation of the adipose renin-angiotensin system (RAS). Interestingly, brain RAS dysregulation is involved in the progression of dopaminergic degeneration and PD. Circulating extracellular vesicles (EVs) from MetS fat tissue can cross the brain-blood barrier and may act as linking signals. We isolated and characterized EVs from MetS and control rats and analyzed their mRNA and protein cargo using RT-PCR and the ExoView R200 platform, respectively. Furthermore, cultures of the N27 dopaminergic cell line and the C6 astrocytic cell line were treated with EVs from MetS rats. EVs were highly increased in MetS rat serum, which was inhibited by treatment of the rats with the angiotensin type-1-receptor blocker candesartan. Furthermore, EVs from MetS rats showed increased pro-oxidative/pro-inflammatory and decreased anti-oxidative/anti-inflammatory RAS components, which were inhibited in candesartan-treated MetS rats. In cultures, EVs from MetS rats increased N27 cell death and modulated C6 cell function, upregulating markers of neuroinflammation and oxidative stress, which were inhibited by the pre-treatment of cultures with candesartan. The results from rat models suggest EVs and their RAS cargo as a mechanism linking Mets and PD.

Extracellular vesicle-based liquid biopsy biomarkers and their application in precision immuno-oncology

While the field of precision oncology is rapidly expanding and more targeted options are revolutionizing cancer treatment paradigms, therapeutic resistance particularly to immunotherapy remains a pressing challenge. This can be largely attributed to the dynamic tumor-stroma interactions that continuously alter the microenvironment. While to date most advancements have been made through examining the clinical utility of tissue-based biomarkers, their invasive nature and lack of a holistic representation of the evolving disease in a real-time manner could result in suboptimal treatment decisions. Thus, using minimally-invasive approaches to identify biomarkers that predict and monitor treatment response as well as alert to the emergence of recurrences is of a critical need. Currently, research efforts are shifting towards developing liquid biopsy-based biomarkers obtained from patients over the course of disease. Liquid biopsy represents a unique opportunity to monitor intercellular communication within the tumor microenvironment which could occur through the exchange of extracellular vesicles (EVs). EVs are lipid bilayer membrane nanoscale vesicles which transfer a plethora of biomolecules that mediate intercellular crosstalk, shape the tumor microenvironment, and modify drug response. The capture of EVs using innovative approaches, such as microfluidics, magnetic beads, and aptamers, allow their analysis via high throughput multi-omics techniques and facilitate their use for biomarker discovery. Artificial intelligence, using machine and deep learning algorithms, is advancing multi-omics analyses to uncover candidate biomarkers and predictive signatures that are key for translation into clinical trials. With the increasing recognition of the role of EVs in mediating immune evasion and as a valuable biomarker source, these real-time snapshots of cellular communication are promising to become an important tool in the field of precision oncology and spur the recognition of strategies to block resistance to immunotherapy. In this review, we discuss the emerging role of EVs in biomarker research describing current advances in their isolation and analysis techniques as well as their function as mediators in the tumor microenvironment. We also highlight recent lung cancer and melanoma studies that point towards their application as predictive biomarkers for immunotherapy and their potential clinical use in precision immuno-oncology.

Exosomal miR-146a-5p derived from human umbilical cord mesenchymal stem cells can alleviate antiphospholipid antibody-induced trophoblast injury and placental dysfunction by regulating the TRAF6/NF-κB axis

Exosomes originating from human umbilical cord mesenchymal stem cells (hucMSC-exos) have become a novel strategy for treating various diseases owing to their ability to regulate intercellular signal communication. However, the potential of hucMSC-exos to improve placental injury in obstetric antiphospholipid syndrome and its underlying mechanism remain unclear. Our objective was to explore the potential application of hucMSC-exos in the treatment of obstetric antiphospholipid syndrome and elucidate its underlying mechanism. In our study, hucMSC-exos ameliorated the functional impairment of trophoblasts caused by antiphospholipid antibodies in vitro and attenuated placental dysfunction in mice with obstetric antiphospholipid syndrome by delivering miR-146a-5p. Exosomal miR-146a-5p suppressed the expression of tumor necrosis factor receptor-associated factor 6 (TRAF6) and inhibited the activation of NF-κB signaling, leading to the down-regulation of IL-1β and IL-18 to rescue inflammation and modulation of Cleaved-CASP3, BAX, and BCL2 to inhibit apoptosis in HTR8/SVneo cells and mice placenta. This study identified the potential molecular basis of how hucMSC-exos improved antiphospholipid antibody-induced placental injury and highlighted the functional importance of the miR-146a-5p/TRAF6 axis in the progression of obstetric antiphospholipid syndrome. More importantly, this study provided a fresh outlook on the promising use of hucMSC-exos as a novel and effective treatment approach in obstetric antiphospholipid syndrome.

Engineering a tunable micropattern-array assay to sort single extracellular vesicles and particles to detect RNA and protein in situ

The molecular heterogeneity of extracellular vesicles (EVs) and the co-isolation of physically similar particles, such as lipoproteins (LPs), confounds and limits the sensitivity of EV bulk biomarker characterization. Herein, we present a single-EV and particle (siEVP) protein and RNA assay (siEVP PRA) to simultaneously detect mRNAs, miRNAs, and proteins in subpopulations of EVs and LPs. The siEVP PRA immobilizes and sorts particles via positive immunoselection onto micropatterns and focuses biomolecular signals in situ. By detecting EVPs at a single-particle resolution, the siEVP PRA outperformed the sensitivities of bulk-analysis benchmark assays for RNA and protein. To assess the specificity of RNA detection in complex biofluids, EVs from various glioma cell lines were processed with small RNA sequencing, whereby two mRNAs and two miRNAs associated with glioblastoma multiforme (GBM) were chosen for cross-validation. Despite the presence of single-EV-LP co-isolates in serum, the siEVP PRA detected GBM-associated vesicular RNA profiles in GBM patient siEVPs. The siEVP PRA effectively examines intravesicular, intervesicular, and interparticle heterogeneity with diagnostic promise.

Exosomal miR-99b-5p Secreted from Mesenchymal Stem Cells Can Retard the Progression of Colorectal Cancer by Targeting FGFR3

Human bone marrow mesenchymal stem cells (BMSCs) are efficient mass producers of exosomes that can potentially be utilized for delivery of miRNAs in cancer therapy. The current study aimed to assess the role of MSC-exosomal miR-99b-5p during the development of colorectal cancer (CRC). The potential value of using plasma levels of exosomal miR-99b-5p for predicting the liver metastasis of colorectal cancer was also assessed. In this study, we found that overexpression of fibroblast growth factor receptor 3 (FGFR3) was associated with tumor progression in CRC and FGFR3 was the target gene of miR-99b-5p, which was down-regulated in CRC tissues. Furthermore, we observed that elevated miR-99b-5p inhibited CRC cell proliferation, invasion and migration, while reduced levels had the opposite effect on CRC cells. Moreover, exosomal miR-99b-5p delivered by BMSCs was able to limit the proliferation, invasion and migration of CRC cells in vitro, as well as suppressing tumor growth in vivo. Collectively, these findings revealed that MSC-derived exosomal miR-99b-5p can be transferred into CRC cells and which can suppress tumor progression by targeting FGFR3. This highlights the potential of using exosomal miR-99b-5p as a novel diagnostic marker for CRC, while providing a therapeutic target to combat CRC.

A noncanonical function of SKP1 regulates the switch between autophagy and unconventional secretion

Intracellular degradation of proteins and organelles by the autophagy-lysosome system is essential for cellular quality control and energy homeostasis. Besides degradation, endolysosomal organelles can fuse with the plasma membrane and contribute to unconventional secretion. Here, we identify a function for mammalian SKP1 in endolysosomes that is independent of its established role as an essential component of the family of SCF/CRL1 ubiquitin ligases. We found that, under nutrient-poor conditions, SKP1 is phosphorylated on Thr131, allowing its interaction with V1 subunits of the vacuolar ATPase (V-ATPase). This event, in turn, promotes V-ATPase assembly to acidify late endosomes and enhance endolysosomal degradation. Under nutrient-rich conditions, SUMOylation of phosphorylated SKP1 allows its binding to and dephosphorylation by the PPM1B phosphatase. Dephosphorylated SKP1 interacts with SEC22B to promote unconventional secretion of the content of less acidified hybrid endosomal/autophagic compartments. Collectively, our study implicates SKP1 phosphorylation as a switch between autophagy and unconventional secretion in a manner dependent on cellular nutrient status.

Toward a human brain extracellular vesicle atlas: Characteristics of extracellular vesicles from different brain regions, including small RNA and protein profiles

Extracellular vesicles (EVs) are released from different cell types in the central nervous system (CNS) and play roles in regulating physiological and pathological functions. Although brain-derived EVs (bdEVs) have been successfully collected from brain tissue, there is not yet a "bdEV Atlas" of EVs from different brain regions. To address this gap, we separated EVs from eight anatomical brain regions of a single individual and subsequently characterized them by count, size, morphology, and protein and RNA content. The greatest particle yield was from cerebellum, while the fewest particles were recovered from the orbitofrontal, postcentral gyrus, and thalamus regions. EV surface phenotyping indicated that CD81 and CD9 were more abundant than CD63 in all regions. Cell-enriched surface markers varied between brain regions. For example, putative neuronal markers NCAM, CD271, and NRCAM were more abundant in medulla, cerebellum, and occipital regions, respectively. These findings, while restricted to tissues from a single individual, suggest that additional studies are warranted to provide more insight into the links between EV heterogeneity and function in the CNS.

mRNA Synthesis and Encapsulation in Ionizable Lipid Nanoparticles

mRNA vaccines have recently generated significant interest due to their success during the COVID-19 pandemic. Their success is due to advances in mRNA design and encapsulation into ionizable lipid nanoparticles (iLNPs). This has highlighted the potential for the use of mRNA-iLNPs in other settings such as cancer, gene therapy, or vaccines for different infectious diseases. Here, we describe the production of mRNA-iLNPs using commercially available reagents that are suitable for use as vaccines and therapeutics. This article contains detailed protocols for the synthesis of mRNA by in vitro transcription with enzymatic capping and tailing and the encapsulation of the mRNA into iLNPs using the ionizable lipid DLin-MC3-DMA. DLin-MC3-DMA is often used as a benchmark for new formulations and provides an efficient delivery vehicle for screening mRNA design. The protocol also describes how the formulation can be adapted to other lipids. Finally, a stepwise methodology is presented for the characterization and quality control of mRNA-iLNPs, including measuring mRNA concentration and encapsulation efficiency, particle size, and zeta potential. © 2023 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Synthesis of mRNA by in vitro transcription and enzymatic capping and tailing Basic Protocol 2: Encapsulation of mRNA into ionizable lipid nanoparticles Alternate Protocol: Small-scale encapsulation of mRNA using preformed vesicles Basic Protocol 3: Characterization and quality control of mRNA ionizable lipid nanoparticles.

Extracellular Vesicles Derived from Mesenchymal Stem Cells as Cell-Free Therapy for Intrauterine Adhesion

Intrauterine adhesion (IUA) can occur after trauma to the basal layer of the endometrium, contributing to severe complications in females, such as infertility and amenorrhea. To date, the proposed therapeutic strategies are targeted to relieve IUA, such as hysteroscopic adhesiolysis, Foley catheter balloon, and hyaluronic acid injection have been applied in the clinic. However, these approaches showed limited effects in alleviating endometrial fibrosis and thin endometrium. Mesenchymal stem cells (MSCs) can offer the potential for endometrium regeneration owing to reduce inflammation and release growth factors. On this basis, MSCs have been proposed as promising methods to treat intrauterine adhesion. However, due to the drawbacks of cell therapy, the possible therapeutic use of extracellular vesicles released by stem cells is raising increasing interest. The paracrine effect, mediated by MSCs derived extracellular vehicles (MSC-EVs), has recently been suggested as a mechanism for their therapeutic properties. Here, we summarizes the main pathological mechanisms involved in intrauterine adhesion, the biogenesis and characteristics of extracellular vesicles, explaining how these vesicles could provide new opportunities for MSCs.

Outer membrane vesicles from a mosquito commensal mediate targeted killing of Plasmodium parasites via the phosphatidylcholine scavenging pathway

The gut microbiota is a crucial modulator of Plasmodium infection in mosquitoes, including the production of anti-Plasmodium effector proteins. But how the commensal-derived effectors are translocated into Plasmodium parasites remains obscure. Here we show that a natural Plasmodium blocking symbiotic bacterium Serratia ureilytica Su_YN1 delivers the effector lipase AmLip to Plasmodium parasites via outer membrane vesicles (OMVs). After a blood meal, host serum strongly induces Su_YN1 to release OMVs and the antimalarial effector protein AmLip into the mosquito gut. AmLip is first secreted into the extracellular space via the T1SS and then preferentially loaded on the OMVs that selectively target the malaria parasite, leading to targeted killing of the parasites. Notably, these serum-induced OMVs incorporate certain serum-derived lipids, such as phosphatidylcholine, which is critical for OMV uptake by Plasmodium via the phosphatidylcholine scavenging pathway. These findings reveal that this gut symbiotic bacterium evolved to deliver secreted effector molecules in the form of extracellular vesicles to selectively attack parasites and render mosquitoes refractory to Plasmodium infection. The discovery of the role of gut commensal-derived OMVs as carriers in cross-kingdom communication between mosquito microbiota and Plasmodium parasites offers a potential innovative strategy for blocking malaria transmission.

Comprehensive characterization of human brain-derived extracellular vesicles using multiple isolation methods: Implications for diagnostic and therapeutic applications

Extracellular vesicles (EVs) have emerged as critical mediators of intercellular communication and promising biomarkers and therapeutics in the central nervous system (CNS). Human brain-derived EVs (BDEVs) provide a comprehensive snapshot of physiological changes in the brain's environment, however, the isolation of BDEVs and the comparison of different methods for this purpose have not been fully investigated. In this study, we compared the yield, morphology, subtypes and protein cargo composition of EVs isolated from the temporal cortex of aged human brains using three established separation methods: size-exclusion chromatography (SEC), phosphatidylserine affinity capture (MagE) and sucrose gradient ultracentrifugation (SG-UC). Our results showed that SG-UC method provided the highest yield and collected larger EVs compared to SEC and MagE methods as assessed by transmission electron microscopy and nanoparticle tracking analysis (NTA). Quantitative tandem mass-tag (TMT) mass spectrometry analysis of EV samples from three different isolation methods identified a total of 1158 proteins, with SG-UC showing the best enrichment of common EV proteins with less contamination of non-EV proteins. In addition, SG-UC samples were enriched in proteins associated with ATP activity and CNS maintenance, and were abundant in neuronal and oligodendrocytic molecules. In contrast, MagE samples were more enriched in molecules related to lipoproteins, cell-substrate junction and microglia, whereas SEC samples were highly enriched in molecules related to extracellular matrix, Alzheimer's disease and astrocytes. Finally, we validated the proteomic results by performing single-particle analysis using the super-resolution microscopy and flow cytometry. Overall, our findings demonstrate the differences in yield, size, enrichment of EV cargo molecules and single EV assay by different isolation methods, suggesting that the choice of isolation method will have significant impact on the downstream analysis and protein discovery.

Label-free discrimination of extracellular vesicles from large lipoproteins

Extracellular vesicles (EVs) are increasingly gaining interest as biomarkers and therapeutics. Accurate sizing and quantification of EVs remain problematic, given their nanometre size range and small scattering cross-sections. This is compounded by the fact that common EV isolation methods result in co-isolation of particles with comparable features. Especially in blood plasma, similarly-sized lipoproteins outnumber EVs to a great extent. Recently, interferometric nanoparticle tracking analysis (iNTA) was introduced as a particle analysis method that enables determining the size and refractive index of nanoparticles with high sensitivity and precision. In this work, we apply iNTA to differentiate between EVs and lipoproteins, and compare its performance to conventional nanoparticle tracking analysis (NTA). We show that iNTA can accurately quantify EVs in artificial EV-lipoprotein mixtures and in plasma-derived EV samples of varying complexity. Conventional NTA could not report on EV numbers, as it was not able to distinguish EVs from lipoproteins. iNTA has the potential to become a new standard for label-free EV characterization in suspension.

Towards optimised extracellular vesicle proteomics from cerebrospinal fluid

The proteomic profile of extracellular vesicles (EVs) from cerebrospinal fluid (CSF) can reveal novel biomarkers for diseases of the brain. Here, we validate an ultrafiltration combined with size-exclusion chromatography (UF-SEC) method for isolation of EVs from canine CSF and probe the effect of starting volume on the EV proteomics profile. First, we performed a literature review of CSF EV articles to define the current state of art, discovering a need for basic characterisation of CSF EVs. Secondly, we isolated EVs from CSF by UF-SEC and characterised the SEC fractions by protein amount, particle count, transmission electron microscopy, and immunoblotting. Data are presented as mean ± standard deviation. Using proteomics, SEC fractions 3-5 were compared and enrichment of EV markers in fraction 3 was detected, whereas fractions 4-5 contained more apolipoproteins. Lastly, we compared starting volumes of pooled CSF (6 ml, 3 ml, 1 ml, and 0.5 ml) to evaluate the effect on the proteomic profile. Even with a 0.5 ml starting volume, 743 ± 77 or 345 ± 88 proteins were identified depending on whether 'matches between runs' was active in MaxQuant. The results confirm that UF-SEC effectively isolates CSF EVs and that EV proteomic analysis can be performed from 0.5 ml of canine CSF.

Chromatographic Scalable Method to Isolate Engineered Extracellular Vesicles Derived from Mesenchymal Stem Cells for the Treatment of Liver Fibrosis in Mice

New therapeutic options for liver cirrhosis are needed. Mesenchymal stem cell (MSC)-derived extracellular vesicles (EVs) have emerged as a promising tool for delivering therapeutic factors in regenerative medicine. Our aim is to establish a new therapeutic tool that employs EVs derived from MSCs to deliver therapeutic factors for liver fibrosis. EVs were isolated from supernatants of adipose tissue MSCs, induced-pluripotent-stem-cell-derived MSCs, and umbilical cord perivascular cells (HUCPVC-EVs) by ion exchange chromatography (IEC). To produce engineered EVs, HUCPVCs were transduced with adenoviruses that code for insulin-like growth factor 1 (AdhIGF-I-HUCPVC-EVs) or green fluorescent protein. EVs were characterized by electron microscopy, flow cytometry, ELISA, and proteomic analysis. We evaluated EVs' antifibrotic effect in thioacetamide-induced liver fibrosis in mice and on hepatic stellate cells in vitro. We found that IEC-isolated HUCPVC-EVs have an analogous phenotype and antifibrotic activity to those isolated by ultracentrifugation. EVs derived from the three MSCs sources showed a similar phenotype and antifibrotic potential. EVs derived from AdhIGF-I-HUCPVC carried IGF-1 and showed a higher therapeutic effect in vitro and in vivo. Remarkably, proteomic analysis revealed that HUCPVC-EVs carry key proteins involved in their antifibrotic process. This scalable MSC-derived EV manufacturing strategy is a promising therapeutic tool for liver fibrosis.