Exosome Biochemistry and Advanced Nanotechnology for Next-Generation Theranostic Platforms

Design and Optimization of the Circulatory Cell-Driven Drug Delivery Platform

Achievement of high targeting efficiency for a drug delivery system remains a challenge of tumor diagnoses and nonsurgery therapies. Although nanoparticle-based drug delivery systems have made great progress in extending circulation time, improving durability, and controlling drug release, the targeting efficiency remains low. And the development is limited to reducing side effects since overall survival rates are mostly unchanged. Therefore, great efforts have been made to explore cell-driven drug delivery systems in the tumor area. Cells, particularly those in the blood circulatory system, meet most of the demands that the nanoparticle-based delivery systems do not. These cells possess extended circulation times and innate chemomigration ability and can activate an immune response that exerts therapeutic effects. However, new challenges have emerged, such as payloads, cell function change, cargo leakage, and in situ release. Generally, employing cells from the blood circulatory system as cargo carriers has achieved great benefits and paved the way for tumor diagnosis and therapy. This review specifically covers (a) the properties of red blood cells, monocytes, macrophages, neutrophils, natural killer cells, T lymphocytes, and mesenchymal stem cells; (b) the loading strategies to balance cargo amounts and cell function balance; (c) the cascade strategies to improve cell-driven targeting delivery efficiency; and (d) the features and applications of cell membranes, artificial cells, and extracellular vesicles in cancer treatment.

Advanced Nanotechnologies for Extracellular Vesicle-Based Liquid Biopsy

Extracellular vesicles (EVs) are emerging as a new source of biomarkers in liquid biopsy because of their wide presence in most body fluids and their ability to load cargoes from disease-related cells. Owing to the crucial role of EVs in disease diagnosis and treatment, significant efforts have been made to isolate, detect, and analyze EVs with high efficiency. A recent overview of advanced EV detection nanotechnologies is discussed here. First, several key challenges in EV-based liquid biopsies are introduced. Then, the related pivotal advances in nanotechnologies for EV isolation based on physical features, chemical affinity, and the combination of nanostructures and chemical affinity are summarized. Next, a summary of high-sensitivity sensors for EV detection and advanced approaches for single EV detection are provided. Later, EV analysis is introduced in practical clinical scenarios, and the application of machine learning in this field is highlighted. Finally, future opportunities for the development of next-generation nanotechnologies for EV detection are presented.

Extracellular Vesicle Nanoarchitectonics for Novel Drug Delivery Applications

Extracellular vesicles (EVs) can transfer intercellular messages in various (patho)physiological processes and transport biomolecules to recipient cells. EVs possess the capacity to evade the immune system and remain stable over long periods, identifying them as natural carriers for drugs and biologics. However, the challenges associated with EVs isolation, heterogeneity, coexistence with homologous biomolecules, and lack of site-specific delivery, have impeded their potential. In recent years, the amalgamation of EVs with rationally engineered nanostructures has been proposed for achieving effective drug loading and site-specific delivery. With the advancement of nanotechnology and nanoarchitectonics, different nanostructures with tunable size, shapes, and surface properties can be integrated with EVs for drug loading, target binding, efficient delivery, and therapeutics. Such integration may enable improved cellular targeting and the protection of encapsulated drugs for enhanced and specific delivery to target cells. This review summarizes the recent development of nanostructure amalgamated EVs for drug delivery, therapeutics, and real-time monitoring of disease progression. With a specific focus on the exosomal cargo, diverse drug delivery system, and biomimetic nanostructures based on EVs for selective drug delivery, this review also chronicles the needs and challenges of EV-based biomimetic nanostructures and provides a future outlook on the strategies posed.

Ultrasensitive Exosome Detection by Modularized SERS Labeling for Postoperative Recurrence Surveillance

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

Cryo-self-assembled silk fibroin sponge as a biodegradable platform for enzyme-responsive delivery of exosomes

Although advances in protein assembly preparation have provided a new platform for drug delivery during tissue engineering, achieving long-term controlled exosome delivery remains a significant challenge. Diffusion-dominated exosome release using protein hydrogels results in burst release of exosomes. Here, a fibroin-based cryo-sponge was developed to provide controlled exosome release. Fibroin chains can self-assemble into silk I structures under ice-cold conditions when annealed above the glass transition temperature. Exosome release is enzyme-responsive, with rates primarily determined by enzymatic degradation of the scaffolds. In vivo experiments have demonstrated that exosomes remain in undigested sponge material for two months, superior to their retention in fibrin glue, a commonly used biomaterial in clinical practice. Fibroin cryo-sponges were implanted subcutaneously in nude mice. The exosome-containing sponge group exhibited better neovascularization and tissue ingrowth effects, demonstrating the efficacy of this exosome-encapsulating strategy by realizing sustained release and maintaining exosome bioactivity. These silk fibroin cryo-sponges containing exosomes provide a new platform for future studies of exosome therapy.

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The glass transition temperature of fibroin solution is affected by ions.

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Silk fibroin could self-assembly into silk I structure when annealed below 0 °C.

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Encapsulation of exosomes into the fibroin cryo-sponge would not destroy the integrity of exosomes.

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The release of exosomes from fibroin cryo-sponges is dominated by scaffold degradation.

Piezo-photocatalytic effect mediating reactive oxygen species burst for cancer catalytic therapy

A piezo-photocatalytic therapy based on thermally treated natural sphalerite nanosheet (NSH700 NS) heterojunction was applied to efficiently induce intracellular ROS burst and apoptosis of cancer cells. Upon ultrasound and laser irradiation, the formation of a polarized electric field and band bending of NSH700 NSs allow the directional separation of charges both in the bulk and their interface, thereby minimizing the probability of charge recombination. The piezo-photocatalytic effect leads to an efficient catalytic performance, exhibiting high-performance superoxide radical (˙O₂^-) and hydroxyl radical (˙OH) generation and glutathione (GSH) depletion, which results in a intracellular ROS burst-triggered apoptosis of cancer cells both in vitro and in vivo.

Designer exosomes enabling tumor targeted efficient chemo/gene/photothermal therapy

Exosomes, endogenous nanosized particles (50-150 nm) secreted and absorbed by cells, have been recently used as diagnostic and therapeutic platforms in cancer treatment. The integration of exosome-based delivery with multiple therapeutic modalities could result in better clinical outcomes and reduced-sided effects. Here, we combined the targeting and biocompatibility of designer exosomes with chemo/gene/photothermal therapy. Our platform consists of exosomes loaded with internalized doxorubicin (DOX, a model cancer drug) and coated with magnetic nanoparticles conjugated with molecular beacons capable of targeting miR-21 for responsive molecular imaging. The coated magnetic nanoparticle enables enrichment of the exosomes at the tumor site by external magnetic field guidance. After the exosomes are gathered at the tumor site, the application of near-infrared radiation (NIR) induces localized hyperthermia and triggers the release of cargoes loaded inside the exosome. The released molecular beacon can target the miR-21 for both imaging and gene silencing. Meanwhile, the released doxorubicin serves to kill the cancer cells. About 91.04 % of cancer cells are killed after treatment with Exo-DOX-Fe₃O₄@PDA-MB under NIR. The ability of the exosome-based method for cancer therapy has been demonstrated by animal models, in which the tumor size is reduced dramatically by 97.57 % with a magnetic field-guided tumor-targeted chemo/gene/photothermal approach. Thus, we expected this designer exosome-mediated multi-mode therapy to be a promising platform for the next-generation precision cancer nanomedicines.

Current strategies in tailoring methods for engineered exosomes and future avenues in biomedical applications

Exosomes are naturally occurring nanovesicles of endosomal origin, responsible for cellular communication. Depending on the cell type, exosomes display disparity in the cargo and are involved in up/down regulation of different biological pathways. Naturally secreted exosomes, owing to their inherent delivery potential, non-immunogenic nature and limited structural resemblance to the cells have emerged as ideal candidates for various drug delivery and therapeutic applications. Moreover, the structural versatility of exosomes provides greater flexibility for surface modifications to be made in the native configuration, by different methods, like genetic-engineering, chemical procedures, physical methods and microfluidic-technology, to enhance the cargo quality for expanded biomedical applications. Post isolation and prior to engineering exosomes for various applications, the internal and external structural compositions of exosomes are studied via different techniques. Efficiency and scalability of the exosome modification methods are pivotal in determining the scope of the technique for clinical applications. This review majorly focuses on different methods employed for engineering exosomes, and advantages/disadvantages associated with different tailoring approaches, along with the efficacy of engineered exosomes in biomedical applications. Further, the review highlights the importance of a relatively recent avenue for delivery of exosomes via scaffold-based delivery of naïve/engineered exosomes for regenerative medicine and tissue engineering. This review is based on the recent knowledge generated in this field and our comprehension in this domain.

MSC-derived small extracellular vesicles overexpressing miR-20a promoted the osteointegration of porous titanium alloy by enhancing osteogenesis via targeting BAMBI

BACKGROUND

Patients with osteoporosis have a high risk of implant loosening due to poor osteointegration, possibly leading to implant failure, implant revision, and refracture. RNA interference therapy is an emerging epigenetic treatment, and we found that miR-20a could enhance osteogenesis. Moreover, small extracellular vesicles (sEVs) derived from bone marrow mesenchymal stem cells (hBM-MSCs) were utilized as nanoscale carriers for the protection and transportation of miR-20a (sEV-20a). In this study, we intended to determine whether sEVs overexpressing miR-20a could exert a superior effect on osteoporotic bone defects and the underlying mechanism.

METHODS

For evaluating the effect of sEV-20a on osteogenesis, in vitro and in vivo studies were performed. In vitro, we first showed that miR-20a was upregulated in the osteogenic process and overexpressed sEVs with miR-20a by the transfection method. Then, the proliferation, migration, and osteogenic differentiation abilities of hBM-MSCs treated with sEV-20a were detected by CCK-8 assays, alkaline phosphatase staining and alizarin red staining, qRT-PCR, and western blot. In vivo, we established an osteoporotic bone defect model and evaluated the effect of sEV-20a on bone formation by micro-CT, sequential fluorescent labeling, and histological analysis. To further explore the mechanism, we applied a bioinformatics method to identify the potential target of miR-20a.

RESULTS

In vitro, sEV-20a was successfully established and proved to promote the migration and osteogenesis of hBM-MSCs. In vivo, sEV-20a promoted osteointegration in an osteoporotic rat model. To further elucidate the related mechanism, we proved that miR-20a could enhance osteogenesis by targeting BAMBI.

CONCLUSIONS

Collectively, the in vitro and in vivo results confirmed that MSC-derived sEV-20a therapy effectively promoted osteoporotic porous titanium alloy osteointegration via pro-osteogenic effects by targeting BAMBI.

AC electrokinetic isolation and detection of extracellular vesicles from dental pulp stem cells: Theoretical simulation incorporating fluid mechanics

Extracellular vesicles (EVs) are cell-derived nanoscale vesicles involved in intracellular communication and the transportation of biomarkers. EVs released by mesenchymal stem cells have been recently reported to play a role in cell-free therapy of many diseases. However, the demand for better research tools to replace the tedious conventional methods used to study EVs is getting stronger. EVs' manipulation using alternating current (AC) electrokinetic forces in a microfluidic device has appeared to be a reliable and sensitive diagnosis and trapping technique. Given that different AC electrokinetic forces may contribute to the overall motion of particles and fluids in a microfluidic device, EVs' electrokinetic trapping must be examined considering all dominant forces involved depending on the experimental conditions. In this paper, AC electrokinetic trapping of EVs using an interdigitated electrode arrays is investigated. A 2D numerical simulation incorporating the two significant AC electrokinetic phenomena (Dielectrophoresis and AC electroosmosis) has been performed. Theoretical predictions are then compared with experimental results and allow for a plausible explanation of observations inconsistent with DEP theory. It is demonstrated that the inconsistencies can be attributed to a significant extent to the contribution of the AC electroosmotic effect.

Biogenesis, Membrane Trafficking, Functions, and Next Generation Nanotherapeutics Medicine of Extracellular Vesicles

Extracellular vesicles (EVs) are a heterogeneous group of membrane-limited vesicles and multi-signal messengers loaded with biomolecules. Exosomes and ectosomes are two different types of EVs generated by all cell types. Their formation depends on local microdomains assembled in endocytic membranes for exosomes and in the plasma membrane for ectosomes. Further, EV release is a fundamental process required for intercellular communication in both normal physiology and pathological conditions to transmit/exchange bioactive molecules to recipient cells and the extracellular environment. The unique structure and composition of EVs enable them to serve as natural nanocarriers, and their physicochemical properties and biological functions can be used to develop next-generation nano and precision medicine. Knowledge of the cellular processes that govern EVs biology and membrane trafficking is essential for their clinical applications. However, in this rapidly expanding field, much remains unknown regarding EV origin, biogenesis, cargo sorting, and secretion, as well as EV-based theranostic platform generation. Hence, we present a comprehensive overview of the recent advances in biogenesis, membrane trafficking, and functions of EVs, highlighting the impact of nanoparticles and oxidative stress on EVs biogenesis and release and finally emphasizing the role of EVs as nanotherapeutic agents.

Phosphatidylcholine-Engineered Exosomes for Enhanced Tumor Cell Uptake and Intracellular Antitumor Drug Delivery

Exosomes derived from non-tumor cells hold great potential as drug delivery vehicles because of their good biosafety and natural transference of bioactive cargo between cells. However, compared to tumor-derived exosomes, efficient delivery is limited by their weak interactions with tumor cells. It is essential to engineer exosomes that improve tumor cellular internalization efficiency. A simple and effective strategy to enhance tumor cell uptake by engineering the exosome membrane lipids can be established by drawing on the role of lipids in tumor exosomes interacting with tumor cells. Amphiphilic phosphatidylcholine (PC) molecules are inserted into the membrane lipid layer of reticulocyte-derived exosomes (Exos) by simple incubation to construct PC-engineered exosomes (PC-Exos). It is demonstrated that PC-Exos showed significantly enhanced tumor cell internalization and uptake rate compared to native Exos, up to a twofold increase. After therapeutic agent loading, PC-Exos remarkably promotes intracellular drug or RNA accumulation in cancer cells, thus showing enhanced in vitro anti-tumor activity. This work demonstrates the crucial role of engineering exosomal lipids in modulating cancer cellular uptake, which may shed light on the design of high-efficiency exosome-based drug delivery carriers.

A Highly Specific Multiple Enhancement Theranostic Nanoprobe for PET/MRI/PAI Image-Guided Radioisotope Combined Photothermal Therapy in Prostate Cancer

An integrated molecular probe for combined tumor-targeted multimodal imaging and therapy in the era of precision medicine requires a multiplexed platform that simultaneously has high targeting specificity, versatile conjugation capability, and biocompatibility. Here, a novel biocompatible melanin nanoprobe (PMNs-II-813) coupled with a highly specific prostate-specific membrane antigen small molecule inhibitor is developed for the targeted multimodal diagnosis and treatment of prostate cancer. The melanin nanoparticles demonstrate photoacoustic imaging and photothermal therapy (PTT) functionalities via strong near-infrared absorption. The imaging contrast agents ⁸⁹ Zr and Mn²⁺ are stably conjugated to the nanoparticles for positron emission tomography (PET) and magnetic resonance imaging (MRI). Fusion PET/MRI with PMNs-II-813 enables the monitoring of treatment effects in real time and lasts for more than 1 week, demonstrating the capability for multimodal theranostics in prostate cancer. Labeling with a therapeutic radionuclide, ¹³¹ I, simultaneously endows the nanoprobe with the capability for radioisotope therapy (RIT) and PTT under triple-modal imaging guidance. Combined PTT and RIT has an inhibitory effect on prostate cancer growth (tumor inhibition rate of ≈93% 20 days after treatment), which is significantly better than that with the single treatment. Overall, it is believed that PMNs-II-813 has potential for clinical translation to treat prostate cancer.

Berberine-loaded M2 macrophage-derived exosomes for spinal cord injury therapy

Spinal cord injury (SCI) causes immune activation of resident macrophages/microglia. Activated macrophages/microglia have two different phenotypes, the pro-inflammatory classically activated (M1) phenotype and the anti-inflammatory alternatively activated (M2) phenotype. M1 phenotype macrophages/microglia are the key factor in inflammation. The treatment of SCI remains a huge challenge due to the nontargeting and inefficiency of anti-inflammatory drugs through the blood-brain barrier (BBB). The purpose of this experiment was to design M2-type primary peritoneal macrophages exosomes (Exos) as a drug carrier for berberine (Ber), which can be efficiently targeted to deliver drugs to the injured spinal cord due to the natural advantage of Exos across the BBB. The Exos with particle size of 125±12 nm were loaded with by an ultrasonic method and the drug loading reached 17.13 ±1.64%. The Ber release experiment showed that the loaded sample (Exos-Ber) exhibited sustained release effect, and the cumulative release amount reached 71.44±2.86% within 48 h. In vitro and in vivo experiments confirmed that the Exos-Ber could decrease the M1 protein marker iNOS, elevate the M2 protein marker CD206 and reduce inflammatory and apoptotic cytokines (TNF-α, IL-1β, IL-6, Caspase 9, Caspase 8), which showed that Exos-Ber had a good anti-inflammatory and anti-apoptotic effect by inducing macrophages/microglia from the M1 phenotype to M2 phenotype polarization. Moreover, the motor function of SCI mice was significantly improved after Exos-Ber treatment, indicating that Exos-Ber is a potential agent for SCI therapy. STATEMENT OF SIGNIFICANCE: Efficient targeting strategy for drug delivery. In addition to good biocompatibility and stealth ability, M2 macrophage-derived Exosomes present natural inflammatory targeting ability. The inflammatory microenvironment after spinal cord injury provides motivation for the targeting of exosomes. Natural drug carrier with higher safety. With the rapid development of nanomaterials, drug carriers have become more selective. However, due to the special microenvironment after central nervous system damage, some non-degradable inorganic materials will increase the pressure of self-healing and even secondary damage to neurons, which has been solved by the emergence of exosomes. Some previous studies used tumor cell line exosomes as drug carriers, but the carcinogenic factors carried by themselves have extremely high hidden dangers, and endogenous macrophage exosomes have absolute advantages over their safety.

The Emerging World of Membrane Vesicles: Functional Relevance, Theranostic Avenues and Tools for Investigating Membrane Function

Lipids are essential components of cell membranes and govern various membrane functions. Lipid organization within membrane plane dictates recruitment of specific proteins and lipids into distinct nanoclusters that initiate cellular signaling while modulating protein and lipid functions. In addition, one of the most versatile function of lipids is the formation of diverse lipid membrane vesicles for regulating various cellular processes including intracellular trafficking of molecular cargo. In this review, we focus on the various kinds of membrane vesicles in eukaryotes and bacteria, their biogenesis, and their multifaceted functional roles in cellular communication, host-pathogen interactions and biotechnological applications. We elaborate on how their distinct lipid composition of membrane vesicles compared to parent cells enables early and non-invasive diagnosis of cancer and tuberculosis, while inspiring vaccine development and drug delivery platforms. Finally, we discuss the use of membrane vesicles as excellent tools for investigating membrane lateral organization and protein sorting, which is otherwise challenging but extremely crucial for normal cellular functioning. We present current limitations in this field and how the same could be addressed to propel a fundamental and technology-oriented future for extracellular membrane vesicles.

Palladium Nanoparticle-Induced Oxidative Stress, Endoplasmic Reticulum Stress, Apoptosis, and Immunomodulation Enhance the Biogenesis and Release of Exosome in Human Leukemia Monocytic Cells (THP-1)

Background

Exosomes are endosome-derived nano-sized vesicles that have emerged as important mediators of intercellular communication and play significant roles in various diseases. However, their applications are rigorously restricted by the limited secretion competence of cells. Therefore, strategies to enhance the production and functions of exosomes are warranted. Studies have shown that nanomaterials can significantly enhance the effects of cells and exosomes in intercellular communication; however, how palladium nanoparticles (PdNPs) enhance exosome release in human leukemia monocytic cells (THP-1) remains unclear. Therefore, this study aimed to address the effect of PdNPs on exosome biogenesis and release in THP-1 cells.

Methods

Exosomes were isolated by ultracentrifugation and ExoQuick^TM and characterized by dynamic light scattering, nanoparticle tracking analysis system, scanning electron microscopy, transmission electron microscopy, EXOCET^TM assay, and fluorescence polarization. The expression levels of exosome markers were analyzed via quantitative reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay.

Results

PdNP treatment enhanced the biogenesis and release of exosomes by inducing oxidative stress, endoplasmic reticulum stress, apoptosis, and immunomodulation. The exosomes were spherical in shape and had an average diameter of 50–80 nm. Exosome production was confirmed via total protein concentration, exosome counts, acetylcholinesterase activity, and neutral sphingomyelinase activity. The expression levels of TSG101, CD9, CD63, and CD81 were significantly higher in PdNP-treated cells than in control cells. Further, cytokine and chemokine levels were significantly higher in exosomes isolated from PdNP-treated THP-1 cells than in those isolated from control cells. THP-1 cells pre-treated with N-acetylcysteine or GW4869 showed significant decreases in PdNP-induced exosome biogenesis and release.

Conclusion

To our knowledge, this is the first study showing that PdNPs stimulate exosome biogenesis and release and simultaneously increase the levels of cytokines and chemokines by modulating various physiological processes. Our findings suggest a reasonable approach to improve the production of exosomes for various therapeutic applications.

Extracellular vesicles in kidneys and their clinical potential in renal diseases

Extracellular vesicles (EVs), such as exosomes and microvesicles, are cell-derived lipid bilayer membrane particles, which deliver information from host cells to recipient cells. EVs are involved in various biological processes including the modulation of the immune response, cell-to-cell communications, thrombosis, and tissue regeneration. Different types of kidney cells are known to release EVs under physiologic as well as pathologic conditions, and recent studies have found that EVs have a pathophysiologic role in different renal diseases. Given the recent advancement in EV isolation and analysis techniques, many studies have shown the diagnostic and therapeutic potential of EVs in various renal diseases, such as acute kidney injury, polycystic kidney disease, chronic kidney disease, kidney transplantation, and renal cell carcinoma. This review updates recent clinical and experimental findings on the role of EVs in renal diseases and highlights the potential clinical applicability of EVs as novel diagnostics and therapeutics.

Engineered Extracellular Vesicles for Cancer Therapy

Extracellular vesicles (EVs) have emerged as a novel cell-free strategy for the treatment of many diseases including cancer. As a result of their natural properties to mediate cell-to-cell communication and their high physiochemical stability and biocompatibility, EVs are considered as excellent delivery vehicles for a variety of therapeutic agents such as nucleic acids and proteins, drugs, and nanomaterials. Increasing studies have shown that EVs can be modified, engineered, or designed to improve their efficiency, specificity, and safety for cancer therapy. Herein, a comprehensive overview of the recent advances in the strategies and methodologies of engineering EVs for scalable production and improved cargo-loading and tumor-targeting is provided. Additionally, the potential applications of engineered EVs in cancer therapy are discussed by presenting prominent examples, and the opportunities and challenges for translating engineered EVs into clinical practice are evaluated.

Prospects and challenges of extracellular vesicle-based drug delivery system: considering cell source

Extracellular vesicles (EVs), including exosomes, microvesicles, and apoptotic bodies, are nanosized membrane vesicles derived from most cell types. Carrying diverse biomolecules from their parent cells, EVs are important mediators of intercellular communication and thus play significant roles in physiological and pathological processes. Owing to their natural biogenesis process, EVs are generated with high biocompatibility, enhanced stability, and limited immunogenicity, which provide multiple advantages as drug delivery systems (DDSs) over traditional synthetic delivery vehicles. EVs have been reported to be used for the delivery of siRNAs, miRNAs, protein, small molecule drugs, nanoparticles, and CRISPR/Cas9 in the treatment of various diseases. As a natural drug delivery vectors, EVs can penetrate into the tissues and be bioengineered to enhance the targetability. Although EVs' characteristics make them ideal for drug delivery, EV-based drug delivery remains challenging, due to lack of standardized isolation and purification methods, limited drug loading efficiency, and insufficient clinical grade production. In this review, we summarized the current knowledge on the application of EVs as DDS from the perspective of different cell origin and weighted the advantages and bottlenecks of EV-based DDS.

Self-Activatable Photo-Extracellular Vesicle for Synergistic Trimodal Anticancer Therapy

Extracellular vesicles (EVs) hold great potential in both disease treatment and drug delivery. However, accurate drug release from EVs, as well as the spontaneous treatment effect cooperation of EVs and drugs at target tissues, is still challenging. Here, an engineered self-activatable photo-EV for synergistic trimodal anticancer therapy is reported. M1 macrophage-derived EVs (M1 EVs) are simultaneously loaded with bis[2,4,5-trichloro-6-(pentyloxycarbonyl) phenyl] oxalate (CPPO), chlorin e6 (Ce6), and prodrug aldoxorubicin (Dox-EMCH). After administration, the as-prepared system actively targets tumor cells because of the tumor-homing capability of M1 EVs, wherein M1 EVs repolarize M2 to M1 macrophages, which not only display immunotherapy effects but also produce H₂ O₂ . The reaction between H₂ O₂ and CPPO generates chemical energy that activates Ce6, creating both chemiluminescence for imaging and singlet oxygen (¹ O₂ ) for photodynamic therapy (PDT). Meanwhile, ¹ O₂ -induced membrane rupture leads to the release of Dox-EMCH, which is then activated and penetrates the deep hypoxic areas of tumors. The synergism of immunotherapy, PDT, and chemotherapy results in potent anticancer efficacy, showing great promise to fight cancers.

Milk exosomes: A biogenic nanocarrier for small molecules and macromolecules to combat cancer

Exosomes are unique biogenic nanocarriers of endocytic origin that are generated from most of the cells and found in biofluids like milk, plasma, saliva, and urine. Bovine milk represents the largest and an economic source for the production of exosomes. In recent past, the utility of the milk exosomes as drug carriers is intensified. Exosomes are emerging for delivery of both small and large therapeutics due to their biocompatibility. In this article, we highlighted the various exosomal isolation techniques, physicochemical properties, their biodistribution, and utility of milk exosomes in delivering the small drug molecules and siRNA to combat cancer.

Roles of Bile-Derived Exosomes in Hepatobiliary Disease

Exosomes are vesicles with a diameter of 30-150 nm produced by living cells and secreted into the extracellular matrix. Exosomes mediate cellular communication by carrying active molecules, such as nucleic acids, proteins, and liposomes. Although exosomes are found in various body fluids, little is known about bile-derived exosomes. This review is the first to summarize the methods of bile storage and isolation of biliary exosomes, highlighting the roles of bile-derived exosomes, especially exosomal noncoding RNAs, in physiological and disease states and discussing their potential clinical applications.

Emerging Antioxidant Paradigm of Mesenchymal Stem Cell-Derived Exosome Therapy

Mesenchymal stem cell-derived exosomes have been under investigation as potential treatments for a diverse range of diseases, and many animal and clinical trials have achieved encouraging results. However, it is well known that the biological activity of the exosomes is key to their therapeutic properties; however, till date, it has not been completely understood. Previous studies have provided different explanations of therapeutic mechanisms of the exosomes, including anti-inflammatory, immunomodulatory, and anti-aging mechanisms. The pathological effects of oxidative stress often include organ damage, inflammation, and disorders of material and energy metabolism. The evidence gathered from research involving animal models indicates that exosomes have antioxidant properties, which can also explain their anti-inflammatory and cytoprotective effects. In this study, we have summarized the antioxidant effects of exosomes in in vivo and in vitro models, and have evaluated the anti-oxidant mechanisms of exosomes by demonstrating a direct reduction in excessive reactive oxygen species (ROS), promotion of intracellular defence of anti-oxidative stress, immunomodulation by inhibiting excess ROS, and alteration of mitochondrial performance. Exosomes exert their cytoprotective and anti-inflammatory properties by regulating the redox environment and oxidative stress, which explains the therapeutic effects of exosomes in a variety of diseases, mechanisms that can be well preserved among different species.

Progress of exosomes in the diagnosis and treatment of lung cancer

The incidence and mortality of lung cancer account for first place all over the world. Lung cancer lacks early diagnostic biomarkers; lung cancer patients are usually diagnosed in both middle and advanced stages and have poor treatment outcomes. It is more important to find the first diagnostic tools for lung cancer with high specificity and sensitivity. Besides, exosomes are usually nanometer-sized bi-layered lipid vesicles formed and produced by various types of cells. As one of the main modes of intercellular communication, they can deliver multiple functional biomolecules, such as DNA, microRNAs, messenger RNA (mRNA), long non-coding RNA, and proteins, and the events as mentioned above affects different physiological processes of recipient cells. It has been reported that exosomes are involved in different types of cancer, including lung cancer. Various studies proved that exosomes are involved in multiple cancer processes such as cell proliferation, metastasis, epithelial-mesenchymal transition (EMT), angiogenesis, and the tumor microenvironment in lung cancer. Tumor-derived exosomes (TEX) contain a variety of stimulatory and inhibitory factors involved in regulating immune response, which can affect the tumor microenvironment (TME) and thus participate in the formation and progression of lung cancer. This review's primary purpose to review the latest research progress of exosomes in diagnosing and treating lung cancer.

In Vivo Tracking of Extracellular Vesicles by Nuclear Imaging: Advances in Radiolabeling Strategies

Extracellular vesicles (EVs) are naturally secreted vesicles that have attracted a large amount of interest in nanomedicine in recent years due to their innate biocompatibility, high stability, low immunogenicity, and important role in cell-to-cell communication during pathological processes. Their versatile nature holds great potential to improve the treatment of several diseases through their use as imaging biomarkers, therapeutic agents, and drug-delivery vehicles. However, the clinical translation of EV-based approaches requires a better understanding of their in vivo behavior. Several imaging technologies have been used for the non-invasive in vivo tracking of EVs, with a particular emphasis on nuclear imaging due to its high sensitivity, unlimited penetration depth and accurate quantification. In this article, we will review the biological function and inherent characteristics of EVs and provide an overview of molecular imaging modalities used for their in vivo monitoring, with a special focus on nuclear imaging. The advantages of radionuclide-based imaging modalities make them a promising tool to validate the use of EVs in the clinical setting, as they have the potential to characterize in vivo the pharmacokinetics and biological behavior of the vesicles. Furthermore, we will discuss the current methods available for radiolabeling EVs, such as covalent binding, encapsulation or intraluminal labeling and membrane radiolabeling, reporting the advantages and drawbacks of each radiolabeling approach.

Activatable nanomedicine for overcoming hypoxia-induced resistance to chemotherapy and inhibiting tumor growth by inducing collaborative apoptosis and ferroptosis in solid tumors

Hypoxia has been firmly correlated to the drug resistance of solid tumors. Alleviation of hypoxia by tumor reoxygenation is expected to sensitize the chemotherapy toward solid tumors. Alternatively, ferroptosis provides a therapeutic strategy to overcome apoptotic resistance and multidrug resistance of solid tumors, collaboratively strengthening the chemotherapy toward hypoxic tumors. Herein, an ultrasound (US)-activatable nanomedicine was developed for overcoming hypoxia-induced resistance to chemotherapy and efficiently inhibiting tumor growth by inducing sensitized apoptosis and collaborative ferroptosis of tumor cells. This nanomedicine was constructed by integrating ferrate and doxorubicin into biocompatible hollow mesoporous silica nanoplatforms, followed by assembling a solid-liquid phase-change material of n-heneicosane. The US-induced mild hyperthermia initiates the phase change of n-heneicosane, enabling US-activated co-release of ferrate and doxorubicin. Results reveal that the released ferrate effectively reacts with water as well as the over-expressed hydrogen peroxide and glutathione in tumor cells, achieving tumor-microenvironment-independent reoxygenation and glutathione-depletion in tumors. The reoxygenation down-regulates expressions of hypoxia-inducible factor 1α and multidrug resistance gene/transporter P-glycoprotein in tumor cells, sensitizing the apoptosis-based doxorubicin chemotherapy. More importantly, exogenous iron metabolism from the nanomedicine initiates intracellular Fenton reactions, leading to reactive oxygen species overproduction and iron-dependent ferroptotic death of tumor cells. Furthermore, the glutathione-depletion inactivates the glutathione peroxidase 4 (GPX4, a critical regulatory target in ferroptosis), inhibiting the reduction of lipid peroxides and reinforcing the ferroptotic cell death. The sensitized chemotherapy together with the iron-dependent ferroptosis of tumor cells play a synergistic role in boosting the growth suppression of hypoxic osteosarcoma in vivo. Additionally, the nanomedicine acts as a nanoprobe for in vivo photoacoustic imaging and glutathione tracking, showing great potential as theranostic agents for hypoxic solid tumors treatment.

Isolation and characterization of exosomes for cancer research

Exosomes are a subset of extracellular vesicles that carry specific combinations of proteins, nucleic acids, metabolites, and lipids. Mounting evidence suggests that exosomes participate in intercellular communication and act as important molecular vehicles in the regulation of numerous physiological and pathological processes, including cancer development. Exosomes are released by various cell types under both normal and pathological conditions, and they can be found in multiple bodily fluids. Moreover, exosomes carrying a wide variety of important macromolecules provide a window into altered cellular or tissue states. Their presence in biological fluids renders them an attractive, minimally invasive approach for liquid biopsies with potential biomarkers for cancer diagnosis, prediction, and surveillance. Due to their biocompatibility and low immunogenicity and cytotoxicity, exosomes have potential clinical applications in the development of innovative therapeutic approaches. Here, we summarize recent advances in various technologies for exosome isolation for cancer research. We outline the functions of exosomes in regulating tumor metastasis, drug resistance, and immune modulation in the context of cancer development. Finally, we discuss prospects and challenges for the clinical development of exosome-based liquid biopsies and therapeutics.

Characterization and stabilization in process development and product formulation for super large proteinaceous particles

Super large proteinaceous particles (SLPPs) such as virus, virus like particles, and extracellular vesicles have successful and promising applications in vaccination, gene therapy, and cancer treatment. The unstable nature, the complex particulate structure and composition are challenges for their manufacturing and applications. Rational design of the processing should be built on the basis of fully understanding the characteristics of these bio-particles. This review highlights useful analytical techniques for characterization and stabilization of SLPPs in the process development and product formulations, including high performance size exclusion chromatography, multi-angle laser light scattering, asymmetrical flow field-flow fractionation, nanoparticle tracking analysis, CZE, differential scanning calorimetry, differential scanning fluorescence, isothermal titration calorimetry , and dual polarization interferometry. These advanced analytical techniques will be helpful in obtaining deep insight into the mechanism related to denaturation of SLPPs, and more importantly, in seeking solutions to preserve their biological functions against deactivation or denaturation. Combination of different physicochemical techniques, and correlation with in vitro or in vivo biological activity analyses, are considered to be the future trend of development in order to guarantee a high quality, safety, and efficacy of SLPPs.

Illuminating Platinum Transportation while Maximizing Therapeutic Efficacy by Gold Nanoclusters via Simultaneous Near-Infrared-I/II Imaging and Glutathione Scavenging

Killing tumor cells with a visualized system is a promising strategy in tumor therapy to achieve minimal side effects and high efficiency. Herein, a theranostic nanomedicine (AuNCs-Pt) is developed based on nanocarrier gold nanoclusters (AuNCs) with bifunctions of both NIR-I/NIR-II imaging and glutathione-scavenging abilities. AuNCs-Pt possesses NIR-II imaging capability on a fatal high-grade serous ovarian cancer (HGSOC) model in the deep abdomen, thus facilitating it to be a promising tool for monitoring platinum transportation. Meanwhile, AuNCs-Pt depletes intracellular glutathione to minimize platinum detoxification, effectively maximizing the chemotherapeutic efficacy of platinum. AuNCs-Pt is used to eradicate the tumor burden in this study on a HGSOC model and a patient-derived tumor xenograft model of hepatocellular carcinoma, suggesting great potential for clinical visualized therapy and platinum drug sensitization.

Mycobacterium tuberculosis extracellular vesicles: exploitation for vaccine technology and diagnostic methods

Tuberculosis (TB) is a fatal epidemic disease usually caused by Mycobacterium tuberculosis (Mtb). Pervasive latent infection, multidrug- and extensively drug-resistant tuberculosis (MDR- and XDR-TB), and TB/HIV co-infection make TB a global health problem, which emphasises the design and development of efficient vaccines and diagnostic biomarkers. Extracellular vesicles (EVs) secretion is a conserved phenomenon in all the domains of life. Various cargos such as nucleic acids, toxins, lipoproteins, and enzymes have been recognised in these nano-sized vesicles that may be involved in bacterial physiology and pathogenesis. The intrinsic adjuvant effect, native immunogenic cargo, sensing by host immune cells, circulation in all body fluids, and comprehensive distribution of antigens introduce EVs as a promising tool for designing novel vaccines, diagnostic biomarkers, and drug delivery systems. Genetic engineering of the EV-producing bacteria and the subsequent production of proper EVs could facilitate the development of the EV-based therapeutic applications. Recently, it was demonstrated that thick-walled mycobacteria release EVs, which contain immunodominant cargos such as lipoglycans and lipoproteins. The present article is a comprehensive review on the recent findings of Mtb EVs biology and the exploitation of EVs for the vaccine technology and diagnostic methods.

Engineering Gadolinium-Integrated Tellurium Nanorods for Theory-Oriented Photonic Hyperthermia in the NIR-II Biowindow

Near-infrared (NIR) light-triggered hyperthermia has exhibited promising prospects in oncology therapy due to the unique merits including minimal invasiveness, monitorable, excellent therapeutic effect, and negligible side effects. Especially, the second NIR biowindow (NIR-II, 1000-1700 nm) with less absorbance and scattering by skin tissue, and deep tissue penetration, has received extensive attention for photonic hyperthermia. Unfortunately, the dissatisfactory photothermal conversion efficiency (PCE) and cumbersome preparation process of photo-driven heat conversion nanomaterials seriously hamper the future clinical application. To combat the aforementioned challenges, high imaging performance and desired therapeutic outcome 1D nanorods are constructed based on gadolinium-integrated tellurium nanorods (Te-Gd). In this system, magnetic resonance (MR) imaging and X-ray computed tomography (CT) imaging-guided photonic hyperthermia can be easily implemented in cooperation with Te-Gd. Importantly, Te-Gd possesses high PCE (41%) in the NIR-II biowindow because the transition of the excited electron can easily occur from the valence band (VB) to the conduction band (CB) on (1 0 1) and (1 0 2) crystal planes. Furthermore, the distinctive photostability, high tumor accumulation, as well as low systemic adverse effects of Te-Gd guarantee the potential in the clinic.

Exosome-Derived LncRNAs in Lung Cancer

As extracellular vesicles, exosomes are released from most cells to perform cell–cell communication. Recent studies have shown that exosomes could be released into tumor microenvironment and blood to promote tumor progression through packaging and transmitting various bioactive molecules, such as cholesterol, proteins, lipids, miRNAs, mRNAs, and long non-coding RNAs (lncRNAs) to distant cells. LncRNAs have emerged as a major class of non-coding transcripts. A lot of LncRNAs have been discovered during the past few years of research on genomics. They have been proven to participate in various biological functions and disease processes through multiple mechanisms. In this review, we analyzed the role of exosome-derived lncRNAs in lung carcinogenesis and metastasis. We also highlight opportunities for the clinical potential of exosomes with specific lncRNAs as biomarkers and therapeutic intervention in lung cancer.

Detection and significance of exosomal mRNA expression profiles in the cerebrospinal fluid of patients with meningeal carcinomatosis

Exosomes are cell-derived membrane vesicles with cargo that can be transported into receiver cells to exert their biological roles. Exosomal RNA signature profiles and exosome-derived proteomics are often used to explore the molecular regulation of diseases, and can mirror the conditional state of their tissue of origin, thus serving as biomarkers. The onset of meningeal carcinomatosis (MC) is concealed, and early diagnosis is difficult. To enable early diagnosis of MC, it is essential to identify new biomarkers. Few studies have investigated the function of exosomes in MC. In this study, high-throughput sequencing was used to examine the mRNA profiles of exosomes in the cerebrospinal fluid (CSF) of patients with MC. We further analyzed the functions and signaling pathways associated with the differentially expressed genes in exosomes to reveal the putative mechanisms by which the exosomal mRNAs function in MC. In summary, this study identified biomarker candidates for MC, and provided new insights into the significant role of exosomal mRNA regulation in MC.

Reversal of the immunosuppressive tumor microenvironment by nanoparticle-based activation of immune-associated cells

Immunotherapy that activates the host immune system to reverse immunosuppression has emerged as a new generation of cancer treatment in both preclinical studies and clinical trials. Although immunotherapy has shown significant achievements in the treatment of various cancers, it faces challenges that limit its further evolution such as poor permeation and modest responsiveness. The development of nanoparticle drug delivery system has provided an opportunity to overcome these drawbacks and to achieve optimized immunotherapy. Based on the research of our group, we here introduce the new strategies being employed using nanoscale intelligent drug delivery systems to enhance the effects of cancer immunotherapy. We also provide a perspective on the further possible application of nanoparticles in more effective antitumor immunotherapy.

Novel potential tumor biomarkers: Circular RNAs and exosomal circular RNAs in gastrointestinal malignancies

BACKGROUND

Circular RNAs (circRNAs) are structural ubiquitous RNA molecules. Accumulating evidences have elucidated that circRNAs play essential roles in the pathogenesis of diseases including cancers. Exosomal circRNAs are those circRNAs stably existing in exosomes and having high clinical values as novel potential diagnostic biomarkers of many diseases. Gastrointestinal (GI) malignancies, including pancreatic cancer, colorectal cancer, hepatocellular carcinoma (HCC), and gastric cancer, are leading causes of mortality worldwide and a major global health burden. However, no ideal tumor biomarkers of screening early GI cancers are currently available.

METHODS

We collected data through Web of Science. The search terms used were as follows: circular RNA, circRNA, exosomes, exosomal circRNAs, biomarkers, gastrointestinal malignancies, pancreatic cancer, hepatocellular carcinoma, HCC, gastric cancer, colorectal cancer, physiological functions, biogenesis, molecular mechanism. Only articles published in English were included.

RESULTS

We found that several circRNAs and exosomal circRNAs have been used as potential biomarkers to screen GI cancers including pancreatic cancer (hsa_circ_0001649, circ_0007534, circ_0030235, circRHOT1, circZMYM2, circ-LDLRAD3, chr14:101402109-101464448C, chr4:52729603-52780244C, circ-IARS, and circ-PDE8A), HCC (circSETD3, circADAMTS13, hsa_circ_0007874, hsa_circ_104135, circFBLIM1, cSMARCA5, circRNA-100338, and circPTGR1), colorectal cancer (hsa_circ_0001178, hsa_circ_0000826, hsa_circ_0004771, circDDX17, circITGA7, and circHIPK3), and gastric cancer (hsa_circ_0074362, circNRIP1, circAKT3, circ-DONSON, circPSMC3, circ-KIAA1244, circPVRL3, circPVT1, hsa_circ_0000096, ciRS-133, hsa_circ_0001017, and hsa_circ_0061276).

CONCLUSION

CircRNAs and exosomal circRNAs have the potential high clinical diagnostic values for GI malignancies.

Zeolites for theranostic applications

Theranostic platforms bring about a revolution in disease management. During recent years, theranostic nanoparticles have been utilized for imaging and therapy simultaneously. Zeolites, because of their porous structure and tunable properties, which can be modified with various materials, can be used as a delivery agent. The porous structure of a zeolite enables it to be loaded and unloaded with various molecules such as therapeutic agents, photosensitizers, biological macromolecules, MRI contrast agents, radiopharmaceuticals, near-infrared (NIR) fluorophores, and microbubbles. Furthermore, theranostic zeolite nanocarriers can be further modified with targeting ligands, which is highly interesting for targeted cancer therapies.

Engineering blood exosomes for tumor-targeting efficient gene/chemo combination therapy

Rationale: Developing an effective nanoplatform to realize 'multi-in-one' is essential to broaden the therapeutic potential of combination therapy. Exosomes are ideal candidates since their intrinsic abilities of integrating multiple contents and functions. However, only limited efforts have been devoted to engineering exosomes to integrate the needed properties, also considering the safety and yield, for tumor-targeted and efficient gene/chemo combination therapy.

Methods: Herein, by manipulating the exosome membrane, blood exosomes with high abundance and safety are engineered as a versatile combinatorial delivery system, where the doxorubicin (Dox) and cholesterol-modified miRNA21 inhibitor (miR-21i) are co-embedded into the lipid bilayer of exosomes, and the magnetic molecules and endosomolytic peptides L17E are bind to the exosome membrane through ligand-receptor coupling and electrostatic interactions, respectively.

Results: It is proved that such engineering strategy not only preserves their intrinsic features, but also readily integrates multiple properties of tumor targeting, efficient transfection and gene/chemo combination therapy into blood exosomes. The lipid bilayer structure of exosomes allows them to co-load Dox and miR-21i with high-payloads. Moreover, profiting from the integration of magnetic molecules and L17E peptides, the engineered exosomes exhibit an enhanced tumor accumulation and an improved endosome escape ability, thereby specifically and efficiently delivering encapsulated cargos to tumor cells. As a result, a remarkable inhibition of tumor growth is observed in the tumor-bearing mice, and without noticeable side effects.

Conclusions: This study demonstrates the potential of engineered blood exosomes as feasible co-delivery nanosystem for tumor-targeted and efficient combination therapy. Further development by replacing the drugs combined regimens can potentially make this engineered exosome become a general platform for the design of safe and effective combination therapy modality.

Endothelial Progenitor Cell-Derived Extracellular Vesicles: A Novel Candidate for Regenerative Medicine and Disease Treatment

Extracellular vesicles (EVs) are a heterogeneous group of membranous structures, which can be secreted by most cell types. As a product of paracrine secretion, EVs are considered to be a regulatory mediator for intercellular communication. There are many bioactive cargos in EVs, such as proteins, lipids, and nucleic acids. As the precursor cell of vascular endothelial cells (ECs), endothelial progenitor cells (EPCs) are first discovered in peripheral blood. With the development of studies about the functions of EPCs, an increasing number of researchers focus on EPC-derived EVs (EPC-EVs). EPC-EVs exert key functions for promoting angiogenesis in regenerative medicine and show significant therapeutic effects on a variety of diseases such as circulatory diseases, kidney diseases, diabetes, bone diseases, and tissue/organ damages. This article reviews the current knowledge on the role of EPC-EVs in regenerative medicine and disease treatment, discussing the main challenges and future directions in this field.

The essential role of osteoclast-derived exosomes in magnetic nanoparticle-infiltrated hydroxyapatite scaffold modulated osteoblast proliferation in an osteoporosis model

Magnetic hydroxyapatite (MHA) scaffolds promoted osteoblast proliferation in a model of osteoporosis through altering the osteoclast-derived exosomal cargo and decreasing the efficiency of exosome uptake by osteoblasts. Noticeably, certain proteins including ubiquitin, ATP and reactive oxygen species decreased in the osteoclast-derived exosomal cargo with MHA stimulation, while Rho kinase increased.

Molecular function predictions and diagnostic value analysis of plasma exosomal miRNAs in Hirschsprung's disease

Aim: To discover the potential roles of plasma exosomal miRNAs in Hirschsprung's disease (HSCR) and identify potential noninvasive biomarkers for early diagnosis of HSCR. Materials & methods: Plasma samples were collected from HSCR patients and matched controls. Exosomes were isolated before high-throughput Illumina sequencing was utilized to gain a profile of dysregulated exosomal miRNAs, followed with further verification in two separate cohorts. Bioinformatics analyses were also adopted to explore the molecular functions of dysregulated miRNAs in Hirschsprung's disease. Results & conclusion: 31 dysregulated miRNAs were identified with five considered as promising HSCR signatures. Gene enrichment analysis disclosed that the upregulated miRNAs were most likely to participate in 'extracellular matrix-receptor interaction' and contribute to HSCR through interfering in cell junctions.

Surface plasmon resonance assay for exosomes based on aptamer recognition and polydopamine-functionalized gold nanoparticles for signal amplification

A novel surface plasmon resonance (SPR) strategy is introduced for the specific determination of exosomes based on aptamer recognition and polydopamine-functionalized gold nanoparticle (Au@PDA NP)-assisted signal amplification. Exosomes derived from hepatic carcinoma SMMC-7721 were selected as the model target. SMMC-7721 exosomes can be specifically captured by the aptamer ZY-sls that was complementary to the DNA tetrahedron probes (DTPs), and then the CD63 aptamer-linked Au@PDA NPs recognized SMMC-7721 exosomes for signal amplification. The DTPs were modified on a Au film for preventing Au deposition on the surface during the introduction of HAuCl₄, and PDA coated on the AuNPs was used to reduce HAuCl₄ in situ without any reductant assistance. It results in a further enhanced SPR signal. The assay can clearly distinguish SMMC-7721 exosomes from others (HepG2 exosomes, Bel-7404 exosomes, L02 exosomes, MCF-7 exosomes, and SW480 exosomes, respectively). SMMC-7721 exosomes are specifically determined as low as 5.6 × 10⁵ particles mL^-1. The method has successfully achieved specific determination of SMMC-7721 exosomes even in 50% of human serum without any pretreatment. Graphical abstract A novel surface plasmon resonance (SPR) strategy was introduced for the specific determination of exosomes based on aptamer recognition and polydopamine functionalized gold nanoparticles (Au@PDA NPs). The SPR signal was improved using the Au@PDA NPs assisted amplification.

Bioinspired exosome-like therapeutics and delivery nanoplatforms

Exosomes have emerged as appealing candidate therapeutic agents and delivery nanoplatforms due to their endogenous features and unique biological properties. However, obstacles such as low isolation yield, considerable complexity and potential safety concerns, and inefficient drug payload substantially hamper their therapeutic applicability. To this end, developing bioinspired exosome-like nanoparticles has become a promising area to overcome certain limitations of their natural counterparts. Synthetically fabrication of exosome-like nanoparticles that harbor only crucial components of exosomes through controllable protocols strongly increases the pharmaceutical acceptability of these vesicles. Assembly of exosome-like nanovesicles derived from producer cells allows for a promising strategy for scale-up production. To improve the loading capability and delivery efficiency of exosomes, hybrid exosome-like nanovesicles and membrane-camouflaged nanoparticles towards better bridging synthetic nanocarriers with natural exosomes could be designed. Building off these observations, herein, efforts are made to give an overview of bioinspired exosome-like therapeutics and delivery nanoplatforms. We briefly recapitulate the recent advance in exosome biology with focus on tailoring exosomes as therapeutics and delivery vehicles. Furthermore, we elaborately discuss the biomimicry methodologies for preparation of exosome-like nanoparticles with special emphasis on offering insights into strategies for rational design of exosome-like biomaterials as effective and safe therapeutics and delivery nanoplatforms.

Fibroblast Growth Factor 2-Mediated Regulation of Neuronal Exosome Release Depends on VAMP3/Cellubrevin in Hippocampal Neurons

Extracellular vesicles (EVs) are endogenous membrane-derived vesicles that shuttle bioactive molecules between glia and neurons, thereby promoting neuronal survival and plasticity in the central nervous system (CNS) and contributing to neurodegenerative conditions. Although EVs hold great potential as CNS theranostic nanocarriers, the specific molecular factors that regulate neuronal EV uptake and release are currently unknown. A combination of patch-clamp electrophysiology and pH-sensitive dye imaging is used to examine stimulus-evoked EV release in individual neurons in real time. Whereas spontaneous electrical activity and the application of a high-frequency stimulus induce a slow and prolonged fusion of multivesicular bodies (MVBs) with the plasma membrane (PM) in a subset of cells, the neurotrophic factor basic fibroblast growth factor (bFGF) greatly increases the rate of stimulus-evoked MVB-PM fusion events and, consequently, the abundance of EVs in the culture medium. Proteomic analysis of neuronal EVs demonstrates bFGF increases the abundance of the v-SNARE vesicle-associated membrane protein 3 (VAMP3, cellubrevin) on EVs. Conversely, knocking-down VAMP3 in cultured neurons attenuates the effect of bFGF on EV release. The results determine the temporal characteristics of MVB-PM fusion in hippocampal neurons and reveal a new function for bFGF signaling in controlling neuronal EV release.

Progress in Microfluidics-Based Exosome Separation and Detection Technologies for Diagnostic Applications

Exosomes are secreted by most cell types and circulate in body fluids. Recent studies have revealed that exosomes play a significant role in intercellular communication and are closely associated with the pathogenesis of disease. Therefore, exosomes are considered promising biomarkers for disease diagnosis. However, exosomes are always mixed with other components of body fluids. Consequently, separation methods for exosomes that allow high-purity and high-throughput separation with a high recovery rate and detection techniques for exosomes that are rapid, highly sensitive, highly specific, and have a low detection limit are indispensable for diagnostic applications. For decades, many exosome separation and detection techniques have been developed to achieve the aforementioned goals. However, in most cases, these two techniques are performed separately, which increases operation complexity, time consumption, and cost. The emergence of microfluidics offers a promising way to integrate exosome separation and detection functions into a single chip. Herein, an overview of conventional and microfluidics-based techniques for exosome separation and detection is presented. Moreover, the advantages and drawbacks of these techniques are compared.