Surface modification of extracellular vesicles with polyoxazolines to enhance their plasma stability and tumor accumulation.

Extracellular vesicles (EVs) are future promising therapeutics, but their instability in vivo after administration remains an important barrier to their further development. Many groups evaluated EV surface modification strategies to add a targeting group with the aim of controlling EV biodistribution. Conversely, fewer groups focused on their stabilization to obtain "stealth" allogenic EVs. Modulating their stabilization and biodistribution is an essential prerequisite for their development as nano-therapeutics. Here, we explored polyoxazolines with lipid anchors association to the EV membrane (POxylation as an alternative to PEGylation) to stabilize EVs in plasma and control their biodistribution, while preserving their native properties. We found that this modification maintained and seemed to potentiate the immunomodulatory properties of EVs derived from mesenchymal stem/stromal cells (MSC). Using a radiolabeling protocol to track EVs at a therapeutically relevant concentration in vivo, we demonstrated that POxylation is a promising option to stabilize EVs in plasma because it increased EV half-life by 6 fold at 6 h post-injection. Moreover, EV accumulation in tumors was higher after POxylation than after PEGylation.

Enhancing Extracellular Vesicle Detection via Cotargeting Tetraspanin Biomarkers.

Extracellular vesicles (EVs) are emerging as key diagnostic biomarkers due to their widespread presence in body fluids and the proteins on their surfaces, which reflect the identity and condition of their parent cells. Research has focused on detecting EVs with biosensors that target individual transmembrane proteins (TMPs) like tetraspanins. However, due to TMP heterogeneity and the formation of tetraspanin-enriched microdomains (TEMs), cotargeting multiple TMPs is a promising strategy for enhancing EV detection. In this work, we introduce a dual-antibody surface functionalization approach using surface plasmon resonance (SPR) biosensors to cotarget tetraspanins on EVs derived from mouse macrophages. The expression of EV tetraspanin markers followed the trend of CD9 > CD63 > CD81, which was consistent with the EV detection targeting their nontetraspanin partners, exhibiting LFA-1 > ICAM-1 > VCAM-1, and suggesting a differential role of tetraspanins with their associated TMPs. Cotargeting EV tetraspanins via CD81/CD63, CD81/CD9, and CD63/CD9 dual monoclonal antibody surfaces resulted in higher EV detection compared to predictions based on binding with two monoclonal antibodies against tetraspanins without cotargeting. Furthermore, the optimization of dual monoclonal antibody surface ratios to improve cotargeting effect yielded a statistically significant enhancement in the sensitivity of EV detection. These findings underscore the importance of TEMs in designing EV-based biosensing platforms to achieve optimized sensitivity in EV detection.

Simultaneous Multi-miRNA Detection in Urinary Small Extracellular Vesicles Using Target-Triggered Locked Hairpin DNA-Functionalized Au Nanoprobes for Systemic Lupus Erythematosus Diagnosis.

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by multiorgan involvement and complex clinical manifestations, leading to cumbersome diagnostic processes. MicroRNAs (miRNAs) in small extracellular vesicles (sEVs) have emerged as promising biomarkers for liquid biopsy. Herein, we constructed a simple multi-miRNA detection platform based on target-triggered locked hairpin DNA-functionalized Au nanoprobes (AuNP@LH) as a simple and noninvasive tool for the diagnosis and classification of SLE. The nanoprobes were prepared by modifying locked hairpin DNA designed for target miRNAs on gold nanoparticles. In the presence of target miRNAs, target-triggered hairpin assembly amplification was induced, and then fluorophore-labeled bolt DNA was released, resulting in a fluorescence signal responsive to miRNA concentration. Benefiting from the enzyme-free amplification strategy, the limits of detection (LOD) of three miRNA biomarkers for SLE were 19 pM for microRNA-146a, 66 pM for microRNA-29c, and 19 pM for microRNA-150. The proposed probes have been successfully applied to simultaneously detect multiple miRNAs in urinary sEVs from patients diagnosed with SLE and healthy controls, which exhibited good practicability in SLE diagnosis with the area under curve (AUC) of the receiver characteristic curve reaching 1.00. Furthermore, SLE patients with different disease severity can be differentiated with 81.2% accuracy. Predictably, with the advantages of low cost, rapidity, high sensitivity, and noninvasiveness, our multi-miRNA detection platform is a potential tool for multiple miRNA analysis and related clinical applications.

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.

Snorkel-tag based affinity chromatography for recombinant extracellular vesicle purification.

Extracellular vesicles (EVs) are lipid nanoparticles and play an important role in cell-cell communications, making them potential therapeutic agents and allowing to engineer for targeted drug delivery. The expanding applications of EVs in next generation medicine is still limited by existing tools for scaling standardized EV production, single EV tracing and analytics, and thus provide only a snapshot of tissue-specific EV cargo information. Here, we present the Snorkel-tag, for which we have genetically fused the EV surface marker protein CD81, to a series of tags with an additional transmembrane domain to be displayed on the EV surface, resembling a snorkel. This system enables the affinity purification of EVs from complex matrices in a non-destructive form while maintaining EV characteristics in terms of surface protein profiles, associated miRNA patterns and uptake into a model cell line. Therefore, we consider the Snorkel-tag to be a widely applicable tool in EV research, allowing for efficient preparation of EV standards and reference materials, or dissecting EVs with different surface markers when fusing to other tetraspanins in vitro or in vivo.

Protein profile of extracellular vesicles derived from adult Parascaris spp.

BACKGROUND: Parascaris spp. represent a significant threat to equine health worldwide, particularly in foals. The long-term survival of parasites in the host necessitates persistent modulation of the host immune response. Intercellular communication achieved through the exchange of molecules via extracellular vesicles (EVs) released from the parasite could be a crucial factor in this regard. This study aimed to isolate and characterize EVs released by adult male and female Parascaris worms and conduct a proteomic analysis to identify sex-specific proteins and potential immunomodulatory factors. METHODS: Live adult Parascaris worms were collected, and EVs were isolated from spent culture media using differential ultracentrifugation. Nanoparticle tracking analysis and transmission electron microscopy confirmed the size, concentration, and morphology of the isolated EVs. Proteins within the isolated EVs were analyzed using mass spectrometry-based proteomics (LC-MS/MS). RESULTS: Proteomic analysis revealed a total of 113 proteins in Parascaris EVs, with several proteins showing homology to known helminth exosome proteins and exhibiting immunomodulatory functions. Sex-specific differences in EV protein composition were observed, with a distinct abundance of C-type lectins in female EVs, suggesting potential sex-specific roles or regulation. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses revealed metabolic pathways shared between male and female Parascaris EVs, as well as differences in signal transduction, and cell growth and death pathways, indicating sex-specific variations. CONCLUSIONS: These findings imply that Parascaris EVs and their protein cargo are complex. This data potentially opens avenues for discovering innovative approaches to managing and understanding helminth infection.

Development of complementary analytical methods to characterize extracellular vesicles.

BACKGROUND: Extracellular vesicles (EVs) are involved in intercellular communication and various biological processes. They hold clinical promise for the diagnosis and management of a wide range of pathologies, including cancer, cardiovascular diseases and degenerative diseases, and are of interest as regenerative therapies. Understanding the complex structure of these EVs is essential to perceive the current challenges associated with their analysis and characterization. Today, challenges remain in terms of access to high-yield, high-purity isolation methods, as well as analytical methods for characterizing and controlling the quality of these products for clinical use. RESULTS: We isolated EVs from the same immortalized human cell culture supernatant using two commonly used approaches, namely differential ultracentrifugation and membrane affinity. Then we evaluated EV morphology, size, zeta potential, particle and protein content, as well as protein identity using cryogenic electron microscopy, nanoparticle tracking analysis, asymmetric field flow fractionation (AF4) and size exclusion chromatography (SEC) coupled to multi angle light scattering, bicinchoninic acid assay, electrophoretic light scattering, western blotting and high-resolution mass spectrometry. Compared to membrane affinity isolation, dUC is a more efficient isolation process for obtaining particles with the characteristics expected for EVs and more specifically for exosomes. To validate an isolation process, cryogenic electron microscopy is essential to confirm vesicles with membranes. High resolution mass spectrometry is powerful for understanding the mechanism of action of vesicles. Separative methods, such as AF4 and SEC, are interesting for separating vesicle subpopulations and contaminants. SIGNIFICANCE: This study provides a critical assessment of eight different techniques for analyzing EVs, some of which are mandatory for in-depth characterization and deciphering, while others are more appropriate for routine analysis, once the production and isolation process has been validated. The strengths and limitations of the different approaches used are highlighted.

Thermosensitive hydrogel as a sustained release carrier for mesenchymal stem cell-derived extracellular vesicles in the treatment of intrauterine adhesion.

Intrauterine adhesion (IUA), a prevalent etiology of female infertility, is attributed to endometrial damage. However, conventional therapeutic interventions for IUA are plagued by high recurrence rates. Human umbilical cord mesenchymal stem cell-derived extracellular vesicles (hUCMSC-EVs) demonstrate the promising therapeutic effects on IUA, but the current efficacy of extracellular vesicles (EVs) is hindered by lower retention and bioavailability. In this study, a thermosensitive hydrogel was utilized as a prolonged release carrier to improve the retention and bioavailability of hUCMSC-EVs in IUA treatment. The hydrogel-EVs complex effectively prolonged EVs retention in human endometrial stromal cells and an IUA mouse model. The complex exhibited superior protection against cellular injury, significantly alleviated endometrial damage, inhibited fibrosis, suppressed inflammation, and improved fertility compared to EVs alone. The results indicated that thermosensitive hydrogel enhanced the therapeutic capacity of EVs for IUA by prolonging their retention in the uterine environment. The hydrogel-EVs complex provides a novel strategy for the sustained release of hUCMSC-EVs in the treatment of IUA.

In Situ, Fusion-Free, Multiplexed Detection of Small Extracellular Vesicle miRNAs for Cancer Diagnostics.

Tumor-derived small extracellular vesicle (sEV) microRNAs (miRNAs) are emerging biomarkers for cancer diagnostics. Conventional sEV miRNA detection methods necessitate the lysis of sEVs, rendering them laborious and time-consuming and potentially leading to damage or loss of miRNAs. Membrane fusion-based in situ detection of sEV miRNAs involves the preparation of probe-loaded vesicles (e.g., liposomes or cellular vesicles), which are typically sophisticated and require specialist equipment. Membrane perforation methods employ chemical treatments that can induce severe miRNA degradation or leaks. Inspired by previous studies that loaded nucleic acids into EVs or cells using hydrophobic tethers for therapeutic applications, herein, we repurposed this strategy by conjugating a hydrophobic tether onto molecular beacons to aid their transportation into sEVs, allowing for in situ detection of miRNAs in a fusion-free and multiplexing manner. This method enables simultaneous detection of multiple miRNA species within serum-derived sEVs for the diagnosis of prostate cancer, breast cancer, and gastric cancer with an accuracy of 83.3%, 81.8%, and 100%, respectively, in a cohort of 66 individuals, indicating that it holds a high application potential in clinical diagnostics.

Incorporation of small extracellular vesicles in PEG/HA-Bio-Oss hydrogel composite scaffold for bone regeneration.

Stem cell derived small extracellular vesicles (sEVs) have emerged as promising nanomaterials for the repair of bone defects. However, low retention of sEVs affects their therapeutic effects. Clinically used natural substitute inorganic bovine bone mineral (Bio-Oss) bone powder lacks high compactibility and efficient osteo-inductivity that limit its clinical application in repairing large bone defects. In this study, a poly ethylene glycol/hyaluronic acid (PEG/HA) hydrogel was used to stabilize Bio-Oss and incorporate rat bone marrow stem cell-derived sEVs (rBMSCs-sEVs) to engineer a PEG/HA-Bio-Oss (PEG/HA-Bio) composite scaffold. Encapsulation and sustained release of sEVs in hydrogel scaffold can enhance the retention of sEVs in targeted area, achieving long-lasting repair effect. Meanwhile, synergistic administration of sEVs and Bio-Oss in cranial defect can improve therapeutic effects. The PEG/HA-Bio composite scaffold showed good mechanical properties and biocompatibility, supporting the growth of rBMSCs. Furthermore, sEVs enhancedin vitrocell proliferation and osteogenic differentiation of rBMSCs. Implantation of sEVs/PEG/HA-Bio in rat cranial defect model promotedin vivobone regeneration, suggesting the great potential of sEVs/PEG/HA-Bio composite scaffold for bone repair and regeneration. Overall, this work provides a strategy of combining hydrogel composite scaffold systems and stem cell-derived sEVs for the application of tissue engineering repair.

Extracellular vesicles containing fullerene derivatives prepared by an exchange reaction for photodynamic therapy.

Extracellular vesicles (EVs) have excellent biocompatibility and long retention times in the circulation and have consequently been expected to be useful as drug-delivery systems. However, their applications have been limited because of the inability to introduce hydrophobic compounds to EVs without the use of harmful organic solvents. Herein, we developed an organic-solvent-free drug-loading technique based on the host exchange reaction. We demonstrated that the exchange reaction enabled quantitative loading of EVs with highly concentrated (0.1 mM) hydrophobic fullerene derivatives. Fullerene derivative-loaded EVs (EVs/C60) could eliminate cancer cell lines more efficiently than fullerene derivative-loaded liposomes (Lip/C60). Moreover, the photodynamic activity of EVs/C60 was fivefold higher than that of the clinically available photosensitizer photofrin. EVs/C60 could efficiently suppress tumor growth in tumor-xenograft model mice.

Cellular Output and Physicochemical Properties of the Membrane-Derived Vesicles Depend on Chemical Stimulants.

Synthetic liposomes are widely used as drug delivery vehicles in biomedical treatments, such as for mRNA-based antiviral vaccines like those recently developed against SARS-CoV-2. Extracellular vesicles (EVs), which are naturally produced by cells, have emerged as a next-generation delivery system. However, key questions regarding their origin within cells remain unresolved. In this regard, plasma membrane vesicles (PMVs), which are essentially produced from the cellular plasma membrane (PM), present a promising alternative. Unfortunately, their properties relevant to biomedical applications have not be extensively studied. Therefore, we conducted a thorough investigation of the methods used in the production of PMVs. By leveraging advanced fluorescence techniques in microscopy and flow cytometry, we demonstrated a strong dependence of the physicochemical attributes of PMVs on the chemicals used during their production. Following established protocols employing chemicals such as paraformaldehyde (PFA), N-ethylmaleimide (NEM) or dl-dithiothreitol (DTT) and by developing a modified NEM-based method that involved a hypotonic shock step, we generated PMVs from THP-1 CD1d cells. We systematically compared key parameters such as vesicle output, their size distribution, vesicular content analysis, vesicular membrane lipid organization and the mobility of a transmembrane protein. Our results revealed distinct trends: PMVs isolated using NEM-based protocols closely resembled natural vesicles, whereas PFA induced significant molecular cross-linking, leading to notable changes in the biophysical properties of the vesicles. Furthermore, our novel NEM protocol enhanced the efficiency of PMV production. In conclusion, our study highlights the unique characteristics of chemically produced PMVs and offers insights into their potentially diverse yet valuable biological functions.

Mitochondrial Extracellular Vesicles: A Promising Avenue for Diagnosing and Treating Lung Diseases.

Mitochondria, pivotal organelles governing cellular biosynthesis, energy metabolism, and signal transduction, maintain dynamic equilibrium through processes such as biogenesis, fusion, fission, and mitophagy. Growing evidence implicates mitochondrial dysfunction in a spectrum of respiratory diseases including acute lung injury/acute respiratory distress syndrome, bronchial asthma, pulmonary fibrosis, chronic obstructive pulmonary disease, and lung cancer. Consequently, identifying methods capable of ameliorating damaged mitochondrial function is crucial for the treatment of pulmonary diseases. Extracellular vesicles (EVs), nanosized membrane vesicles released by cells into the extracellular space, facilitate intercellular communication by transferring bioactive substances or signals between cells or organs. Recent studies have identified abundant mitochondrial components within specific subsets of EVs, termed mitochondrial extracellular vesicles (mitoEVs), whose contents and compositions vary with disease progression. Moreover, mitoEVs have demonstrated reparative mitochondrial functions in injured recipient cells. However, a comprehensive understanding of mitoEVs is currently lacking, limiting their clinical translation prospects. This Review explores the biogenesis, classification, functional mitochondrial cargo, and biological effects of mitoEVs, with a focus on their role in pulmonary diseases. Emphasis is placed on their potential as biological markers and innovative therapeutic strategies in pulmonary diseases, offering fresh insights for mechanistic studies and drug development in various pulmonary disorders.

Hybrid Nanoparticles of Extracellular Vesicles and Gemcitabine Prodrug-Loaded Liposomes with Enhanced Targeting Ability for Effective PDAC Treatment.

Liposomes are applied to various anticancer treatments as representative drug delivery carriers. However, liposomes do not have their own targeting properties; therefore, there are limitations in drug delivery to specific tissues or cells. High targetability in drug delivery is an important factor in improving bioavailability and drug efficacy and reducing side effects; recent research has been actively investigated to modify the surface of liposomes to give them specific functions. In this study, we studied a drug delivery system for anticancer treatment that enhances targeting ability through fusion with exosomes on the surface of liposomes. We designed exosome-liposome hybrid nanoparticles loaded with a gemcitabine prodrug as a treatment for pancreatic ductal adenocarcinoma (PDAC). Membrane fusion with exosomes shows excellent targeting ability to pancreatic cancer cells due to intrinsic targeting ability and expansion of the macropinocytosis pathway.

Predictive Analysis in Oral Cancer Immunotherapy: Profiling Dual PD-L1-Positive Extracellular Vesicle Subtypes with Step-Wedge Microfluidic Chips.

PD-L1-positive extracellular vesicles (PD-L1+ EVs) play a pivotal role as predictive biomarkers in cancer immunotherapy. These vesicles, originating from immune cells (I-PD-L1+ EVs) and tumor cells (T-PD-L1+ EVs), hold distinct clinical predictive values, emphasizing the importance of deeply differentiating the PD-L1+ EV subtypes for effective liquid biopsy analyses. However, current methods such as ELISA lack the ability to differentiate their cellular sources. In this study, a novel step-wedge microfluidic chip that combines magnetic microsphere separation with single-layer fluorescence counting is developed. This chip integrates magnetic microspheres modified with anti-PD-L1 antibodies and fluorescent nanoparticles targeting EpCAM (tumor cell marker) or CD45 (immunocyte marker), enabling simultaneous quantification and sensitive analysis of PD-L1+ EV subpopulations in oral squamous cell carcinoma (OSCC) patients' saliva without background interference. Analysis results indicate reduced levels of I-PD-L1+ EVs in OSCC patients compared to those in healthy individuals, with varying levels of heterogeneous PD-L1+ EVs observed among different patient groups. During immunotherapy, responders exhibit decreased levels of total PD-L1+ EVs and T-PD-L1+ EVs, accompanied by reduced levels of I-PD-L1+ EVs. Conversely, nonresponders show increased levels of I-PD-L1+ EVs. Utilizing the step-wedge microfluidic chip allows for simultaneous detection of PD-L1+ EV subtypes, facilitating the precise prediction of oral cancer immunotherapy outcomes.

Investigating Neuroplasticity Changes Reflected by BDNF Levels in Astrocyte-Derived Extracellular Vesicles in Patients with Depression.

Purpose: To investigate the neuroplasticity hypothesis of depression by measuring brain-derived neurotrophic factor (BDNF) levels in plasma astrocyte-derived extracellular vesicles (ADEVs) and to evaluate their potential as biomarkers for depression compared with plasma BDNF levels. Patients and Methods: Thirty-five patients with major depressive disorder (MDD) and 35 matched healthy controls (HCs) were enrolled. Plasma ADEVs were isolated using a combination of ultracentrifugation and immunoaffinity capture. Isolated ADEVs were validated using transmission electron microscopy, nanoparticle tracking analysis, and Western blotting. BDNF levels were quantified in both ADEVs and plasma. ALG-2-interacting protein X (Alix) and cluster of differentiation 81 (CD81) levels, two established extracellular vesicle markers, were measured in ADEVs. Results: After false discovery rate correction, patients with MDD exhibited higher CD81 levels (P FDR = 0.040) and lower BDNF levels (P FDR = 0.043) in ADEVs than HCs at baseline. BDNF levels in ADEVs normalized to CD81 (P FDR = 0.002) and Alix (P FDR = 0.040) remained consistent with this finding. Following four weeks of selective serotonin reuptake inhibitor treatment (n=10), CD81 levels in ADEVs decreased (P FDR = 0.046), while BDNF levels normalized to CD81 increased (P FDR = 0.022). BDNF levels in ADEVs were more stable than in plasma. Exploratory analysis revealed no correlation between BDNF levels in ADEVs and plasma (ρ=0.117, P = 0.334). Conclusion: This study provides human in vivo evidence supporting the neuroplasticity hypothesis of depression by demonstrating altered BDNF levels in ADEVs. ADEVs may be more suitable for developing biomarkers of depression than plasma-derived biomarkers.

Hydrogel Microneedle Patches Loaded with Stem Cell Mitochondria-Enriched Microvesicles Boost the Chronic Wound Healing.

Rescuing or compensating mitochondrial function represents a promising therapeutic avenue for radiation-induced chronic wounds. Adult stem cell efficacies are primarily dependent on the paracrine secretion of mitochondria-containing extracellular vesicles (EVs). However, effective therapeutic strategies addressing the quantity of mitochondria and mitochondria-delivery system are lacking. Thus, in this study, we aimed to design an effective hydrogel microneedle patch (MNP) loaded with stem cell-derived mitochondria-rich EVs to gradually release and deliver mitochondria into the wound tissues and boost wound healing. We, first, used metformin to enhance mitochondrial biogenesis and thereby increasing the secretion of mitochondria-containing EVs (termed "Met-EVs") in adipose-derived stem cells. To verify the therapeutic effects of Met-EVs, we established an in vitro and an in vivo model of X-ray-induced mitochondrial dysfunction. The Met-EVs ameliorated the mitochondrial dysfunction by rescuing mitochondrial membrane potential, increasing adenosine 5'-triphosphate levels, and decreasing reactive oxygen species production by transferring active mitochondria. To sustain the release of EVs into damaged tissues, we constructed a Met-EVs@Decellularized Adipose Matrix (DAM)/Hyaluronic Acid Methacrylic Acid (HAMA)-MNP. Met-EVs@DAM/HAMA-MNP can load and gradually release Met-EVs and their contained mitochondria into wound tissues to alleviate mitochondrial dysfunction. Moreover, we found Met-EVs@DAM/HAMA-MNP can markedly promote macrophage polarization toward the M2 subtype with anti-inflammatory and regenerative functions, which can, in turn, enhance the healing process in mice with skin wounds combined radiation injuries. Collectively, we successfully fabricated a delivery system for EVs, Met-EVs@DAM/HAMA-MNP, to effectively deliver stem cell-derived mitochondria-rich EVs. The effectiveness of this system has been demonstrated, holding great potential for chronic wound treatments in clinic.

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.

Proteomic Characterization of Transfusable Blood Components: Fresh Frozen Plasma, Cryoprecipitate, and Derived Extracellular Vesicles via Data-Independent Mass Spectrometry.

Extracellular vesicles (EVs) are a heterogeneous collection of particles that play a crucial role in cell-to-cell communication, primarily due to their ability to transport molecules, such as proteins. Thus, profiling EV-associated proteins offers insight into their biological effects. EVs can be isolated from various biological fluids, including donor blood components such as cryoprecipitate and fresh frozen plasma (FFP). In this study, we conducted a proteomic analysis of five single donor units of cryoprecipitate, FFP, and EVs derived from these blood components using a quantitative mass spectrometry approach. EVs were successfully isolated from both cryoprecipitate and FFP based on community guidelines. We identified and quantified approximately 360 proteins across all sample groups. Principal component analysis and heatmaps revealed that both cryoprecipitate and FFP are similar. Similarly, EVs derived from cryoprecipitate and FFP are comparable. However, they differ between the originating fluids and their derived EVs. Using the R-package MS-DAP, differentially expressed proteins (DEPs) were identified. The DEPs for all comparisons, when submitted for gene enrichment analysis, are involved in the complement and coagulation pathways. The protein profile generated from this study will have important clinical implications in increasing our knowledge of the proteins that are associated with EVs derived from blood components.

Injectable Alginate-Based Hydrogels Encapsulating Engineered Endothelial Extracellular Vesicles for the Treatment of Critical Limb Ischemia.

Critical limb ischemia (CLI) is a peripheral arterial disease resulting from chronic inflammation of vascular systems. Recent studies have shown that inhibiting macrophage inflammation has the potential to treat CLI, and extracellular vesicles (EVs) from endothelial cells can inhibit macrophage activation. However, the limited cell-targeting capabilities and rapid clearance of EVs from the injection site limit the in vivo application of the EVs. Here, we modified endothelial EVs with platelet membranes (pM/EVs) to boost the inhibition effects on macrophage inflammation and developed an injectable alginate-based collagen composite (ACC) hydrogel for localized delivery of pM/EVs (pM/EVs@ACC) for CLI treatment. We found that pM/EVs can effectively inhibit macrophage inflammation in vitro. Furthermore, pM/EVs@ACC treatment significantly promotes the recovery of limb functions, restoring the feet' blood supply and relieving inflammation. Our findings provide compelling evidence that the pM/EVs@ACC injectable system mediating delivery of pM/EVs is a promising strategy for CLI treatment.