Cancer therapy based on extracellular vesicles as drug delivery vehicles

MMP2 enzyme-responsive extracellular vesicles as dual-targeted carriers to promote the phagocytosis of macrophages

Combination therapy using inhibition of tumor cell escape and alteration of the tumor microenvironment offers a new strategy for cancer treatment. This study aimed to develop an extracellular vesicle (EV) carrier that regulates tumor cells and the tumor microenvironment to achieve efficient tumor immunotherapy. The ligand modified on carriers targets the immune checkpoint CD47 protein, blocking tumor cell escape. This ligand is cleaved by the MMP2 enzyme and assembles into nanofibers, extending the retention time in the tumor. The carriers target the CD206 protein, enabling efficient uptake by M2 macrophages. Carriers with a high density of ligands (anti-CD206) exhibit strong receptorligand interactions with tumor cells. Due to their high rigidity, these EVs have difficulty deforming during the transmembrane process, reducing resistance and resulting in low uptake efficiency by M2 cells. The optimal uptake efficiency by M2 macrophages is achieved when the mass ratio of ligand to EVs is 1:25. Crocin loaded in EVs facilitates the polarization of M2 macrophages into M1 cells, which can phagocytize tumor cells. This study reveals a potential strategy for using extracellular vesicles in tumor treatment.

Bacterial Extracellular Vesicles: Potential Therapeutic Applications, Challenges, and Future Prospects

Almost all cell types naturally secret extracellular vesicles (EVs) in the extracellular space with variable metabolic cargo facilitating intracellular communication, posing immune-modulation capacity. Thus, "bacterial extracellular vesicles" (BEVs), with their great immunoregulatory, immune response stimulation and disease condition-altering potential, have gained importance in the medical and therapeutic industry. Various subtypes of BEVs were observed and reported in the literature, such as exosomes (30-150 nm), microvesicles (100-1000 nm), apoptotic bodies (1000-5000 nm), and oncosomes (1000-10,000 nm). As biological systems are complex entities, inserting BEVs requires extra high purity. Various techniques for BEV isolation have been employed alone or with other strategies, such as ultracentrifugation, precipitation, size-exclusion chromatography, affinity-based separation, ultrafiltration, and field-flow fractionation. But to date, no BEV isolation method is considered perfect as the lack of standard protocols limits their scale-up. Medical research has focused on BEVs to explore their diverse therapeutic potential. This review particularly focused on the recent advancements in the potential medical application of BEVs, current challenges, and prospects associated with their scale-up.

Characterizing Extracellular Vesicles Generated from the Integra CELLine Culture System and Their Endocytic Pathways for Intracellular Drug Delivery

Extracellular vesicles (EVs) have attracted great attention as promising intracellular drug delivery carriers. While the endocytic pathways of small EVs (sEVs, <200 nm) have been reported, there is limited understanding of large EVs (lEVs, >200 nm), despite their potential applications for drug delivery. Additionally, the low yield of EVs during isolation remains a major challenge in their application. Herein, we aimed to compare the endocytic pathways of sEVs and lEVs using MIA PaCa-2 pancreatic cancer cell-derived EVs as models and to explore the efficiency of their production. The cellular uptake of EVs by MIA PaCa-2 cells was assessed and the pathways were investigated with the aid of endocytic inhibitors. The yield and protein content of sEVs and lEVs from the Integra CELLine culture system and the conventional flasks were compared. Our findings revealed that both sEVs and lEVs produced by the Integra CELLine system entered their parental cells via multiple routes, including caveolin-mediated endocytosis, clathrin-mediated endocytosis, and actin-dependent phagocytosis or macropinocytosis. Notably, caveolin- and clathrin-mediated endocytosis were more prominent in the uptake of sEVs, while actin-dependent phagocytosis and macropinocytosis were significant for both sEVs and lEVs. Compared with conventional flasks, the Integra CELLine system demonstrated a 9-fold increase in sEVs yield and a 6.5-fold increase in lEVs yield, along with 3- to 4-fold higher protein content per 1010 EVs. Given that different endocytic pathways led to distinct intracellular trafficking routes, this study highlights the unique potentials of sEVs and lEVs for intracellular cargo delivery. The Integra CELLine proves to be a highly productive and cost-effective system for generating EVs with favourable properties for drug delivery.

Recent advances to address challenges in extracellular vesicle-based applications for lung cancer

Lung cancer, highly prevalent and the leading cause of cancer-related death globally, persists as a significant challenge due to the lack of definitive tumor markers for early diagnosis and personalized therapeutic interventions. Recently, extracellular vesicles (EVs), functioning as natural carriers for intercellular communication, have received increasing attention due to their ability to traverse biological barriers and deliver diverse biological cargoes, including cytosolic proteins, cell surface proteins, microRNA, lncRNA, circRNA, DNA, and lipids. EVs are increasingly recognized as a valuable resource for non-invasive liquid biopsy, as well as drug delivery platforms, and anticancer vaccines for precision medicine in lung cancer. Herein, given the diagnostic and therapeutic potential of tumor-associated EVs for lung cancer, we discuss this topic from a translational standpoint. We delve into the specific roles that EVs play in lung cancer carcinogenesis and offer a particular perspective on how advanced engineering technologies can overcome the current challenges and expedite and/or enhance the translation of EVs from laboratory research to clinical settings.

The role of mesenchymal stem cells in cancer and prospects for their use in cancer therapeutics

Mesenchymal stem cells (MSCs) are recruited by malignant tumor cells to the tumor microenvironment (TME) and play a crucial role in the initiation and progression of malignant tumors. This role encompasses immune evasion, promotion of angiogenesis, stimulation of cancer cell proliferation, correlation with cancer stem cells, multilineage differentiation within the TME, and development of treatment resistance. Simultaneously, extensive research is exploring the homing effect of MSCs and MSC-derived extracellular vesicles (MSCs-EVs) in tumors, aiming to design them as carriers for antitumor substances. These substances are targeted to deliver antitumor drugs to enhance drug efficacy while reducing drug toxicity. This paper provides a review of the supportive role of MSCs in tumor progression and the associated molecular mechanisms. Additionally, we summarize the latest therapeutic strategies involving engineered MSCs and MSCs-EVs in cancer treatment, including their utilization as carriers for gene therapeutic agents, chemotherapeutics, and oncolytic viruses. We also discuss the distribution and clearance of MSCs and MSCs-EVs upon entry into the body to elucidate the potential of targeted therapies based on MSCs and MSCs-EVs in cancer treatment, along with the challenges they face.

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

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

Advances of machine learning-assisted small extracellular vesicles detection strategy

Detection of extracellular vesicles (EVs), particularly small EVs (sEVs), is of great significance in exploring their physiological characteristics and clinical applications. The heterogeneity of sEVs plays a crucial role in distinguishing different types of cells and diseases. Machine learning, with its exceptional data processing capabilities, offers a solution to overcome the limitations of conventional detection methods for accurately classifying sEV subtypes and sources. Principal component analysis, linear discriminant analysis, partial least squares discriminant analysis, XGBoost, support vector machine, k-nearest neighbor, and deep learning, along with some combined methods such as principal component-linear discriminant analysis, have been successfully applied in the detection and identification of sEVs. This review focuses on machine learning-assisted detection strategies for cell identification and disease prediction via sEVs, and summarizes the integration of these strategies with surface-enhanced Raman scattering, electrochemistry, inductively coupled plasma mass spectrometry and fluorescence. The performance of different machine learning-based detection strategies is compared, and the advantages and limitations of various machine learning models are also evaluated. Finally, we discuss the merits and limitations of the current approaches and briefly outline the perspective of potential research directions in the field of sEV analysis based on machine learning.

The role of extracellular vesicles from placenta and endometrium in pregnancy: Insights from tumor biology

Extracellular vesicles (EVs) are small membrane-bound particles secreted by various cell types that play a critical role in intercellular communication by packaging and delivering biomolecules. In recent years, EVs have emerged as essential messengers in mediating physiological and pathological processes in tumor biology. The tumor microenvironment (TME) plays a pivotal role in tumor generation, progression, and metastasis. In this review, we provide an overview of the impact of tumor-derived EVs on both tumor cells and the TME. Moreover, we draw parallels between tumor biology and pregnancy, as successful embryo implantation also requires intricate intercellular communication between the placental trophecepiblast and the endometrial epithelium. Additionally, we discuss the involvement of EVs in targeting immune responses, trophoblast invasion, migration, and angiogenesis, which are shared biological processes between tumors and pregnancy. Specifically, we highlight the effects of placenta-derived EVs on the fetal-maternal interface, placenta, endometrium, and maternal system, as well as the role of endometrium-derived EVs in embryo-endometrial communication. However, challenges still exist in EVs research, including the standardization of EVs isolation methods for diagnostic testing, which also apply to reproductive systems where EVs-mediated communication is proposed to take place. Through this review, we aim to deepen the understanding of EVs, particularly in the context of reproductive biology, and encourage further investigation in this field.

Extracellular vesicles: powerful candidates in nano-drug delivery systems

Extracellular vesicles (EVs), which are nanoparticles that are actively released by cells, contain a variety of biologically active substances, serve as significant mediators of intercellular communication, and participate in many processes, in health and pathologically. Compared with traditional nanodrug delivery systems (NDDSs), EVs have unique advantages due to their natural physiological properties, such as their biocompatibility, stability, ability to cross barriers, and inherent homing properties. A growing number of studies have reported that EVs deliver therapeutic proteins, small-molecule drugs, siRNAs, miRNAs, therapeutic proteins, and nanomaterials for targeted therapy in various diseases. However, due to the lack of standardized techniques for isolating, quantifying, and characterizing EVs; lower-than-anticipated drug loading efficiency; insufficient clinical production; and potential safety concerns, the practical application of EVs still faces many challenges. Here, we systematically review the current commonly used methods for isolating EVs, summarize the types and methods of loading therapeutic drugs into EVs, and discuss the latest progress in applying EVs as NDDs. Finally, we present the challenges that hinder the clinical application of EVs.

Anti-cancer bioactivity of sweet basil leaf derived extracellular vesicles on pancreatic cancer cells

Most living organisms secrete tiny lipid bilayer particles encapsulating various biomolecular entities, including nucleic acids and proteins. These secreted extracellular vesicles (EVs) are shown to aid in communication between cells and their environment. EVs are mainly involved in the signalling and manipulation of physiological processes. Plant EVs display similar functional activity as seen in mammalian EVs. Medicinal plants have many bioactive constituents with potential applications in cancer treatment. Particularly, Basil (Ocimum basilicum), has wide therapeutic properties including anti-inflammatory, anti-cancer, and anti-infection, among others. In this study, we focused on using EVs purified from Apoplast Washing Fluid (AWF) of Basil plant leaves as a biological therapeutic agent against cancer. Characterization of Basil EVs revealed a size range of 100-250 nm, which were later assessed for their cell uptake and apoptosis inducing abilities in pancreatic cancer cells. Basil plant EVs (BasEVs) showed a significant cytotoxic effect on pancreatic cancer cell line MIA PaCa-2 at a concentration of 80 and 160 μg/mL in cell viability, as well as clonogenic assays. Similarly, RT-PCR and western blot analysis has shown up regulation in apoptotic gene and protein expression of Bax, respectively, in BasEV treatment groups compared to untreated controls of MIA PaCa-2. Overall, our results suggest that EVs from basil plants have potent anti-cancer effects in pancreatic cancer cells and can serve as a drug delivery system, demanding an investigation into the therapeutic potential of other medicinal plant EVs.

Advances and challenges in clinical applications of tumor cell-derived extracellular vesicles

Extracellular vesicles (EVs) are a class of substances that feature vesicle-like structures. Initially deemed to be "biological waste", recent studies have highlighted the crucial role of EVs in mediating information communication between cells by transporting bioactive components. Specifically, tumor cell-derived extracellular vesicles (TEVs) contain components that can be utilized for disease diagnosis and as vaccines to activate the immune system. Moreover, since TEVs have a phospholipid bilayer shell and can transport exogenous substances, they are being increasingly explored as drug delivery vehicles in anti-tumor therapy. TEVs have proven highly compatible with their corresponding tumor cells, allowing for efficient drug delivery and exerting killing effects on tumor cells through various mechanisms such as domino effects, lysosomal pathways, and inhibition of drug efflux from tumor tissues. Despite these promising developments, challenges remain in the clinical applications of EVs derived from tumor cells. This paper outlines the current advances and limitations in this field, highlighting the potential of TEVs as a powerful tool for combating cancer.

Imaging of Light-Enhanced Extracellular Vesicle-Mediated Delivery of Oxaliplatin to Colorectal Cancer Cells via Laser Ablation, Inductively Coupled Plasma Mass Spectrometry

Extracellular vesicles (EVs) are lipid bilayer structures released by all cells that mediate cell-to-cell communication via the transfer of bioactive cargo. Because of the natural origin of EVs, their efficient uptake by recipient cells, capacity to stabilize and transport biomolecules and their potential for cell/tissue targeting and preferential uptake by cancer cells, they have enormous potential for bioengineering into improved and targeted drug delivery systems. In this work, we investigated the use of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) as a tool to measure the loading of platinum-based chemotherapeutic agents. The EV loading of oxaliplatin via co-incubation was demonstrated, and LA-ICP-MS imaging showed greater efficiency of delivery to colorectal cancer cells compared to free oxaliplatin, leading to enhanced cytotoxic effect. Further, the impact of EV co-loading with a porphyrin (C5SHU, known as 'C5') photosensitizer on oxaliplatin delivery was assessed. Fluorescence analysis using nano-flow cytometry showed dose-dependent EV loading as well as a trend towards the loading of larger particles. Exposure of OXA-C5-EV-treated colorectal cancer cells to light indicated that delivery was enhanced by both light exposure and porphyrins, with a synergistic effect on cell viability observed between oxaliplatin, EVs and light exposure after the delivery of the co-loaded EVs. In summary, this work demonstrates the utility of LA-ICP-MS and mass spectrometry imaging in assessing the loading efficiency and cellular delivery of platinum-based therapeutics, which would also be suitable for agents containing other elements, confirms that EVs are more efficient at delivery compared to free drugs, and describes the use of light exposure in optimizing delivery and therapeutic effects of EV-mediated drug delivery both in combination and independently of porphyrin-based photosensitizers.

Engineered exosomes: a promising vehicle in cancer therapy

During the past few decades, researchers have attempted to discover an effective treatment for cancer. Exosomes are natural nanovesicles released by various cells and play a role in communication between cells. While natural exosomes have high clinical potential, their inherent limitations have prompted researchers to design exosomes with improved therapeutic properties. To achieve this purpose, researchers have undertaken exosome engineering to modify the surface properties or internal composition of exosomes. After these modifications, engineered exosomes can be used as carriers for delivery of chemotherapeutic agents, targeted drug delivery or development of cancer vaccines. The present study provides an overview of exosomes, including their biogenesis, biological functions, isolation techniques, engineering methods, and potential applications in cancer therapy.

Ultra-efficient radio-immunotherapy for reprogramming the hypoxic and immunosuppressive tumor microenvironment with durable innate immune memory

Radiosensitization efficacy of conventional tumor radiosensitizers has been frequently limited by insufficient competence for tumor microenvironment (TME) regulation and unfavorable cellular uptake at biological barriers. Here, we reported an ultra-efficient radiotherapy (RT) strategy by synthesizing an extracellular vesicles (EVs)-encapsulated hollow MnO2 to load metformin (Met@HMnER). It demonstrated significant RT enhancement by morphological control of catalyst and cellular respiratory depression against conventional solid MnO2. Furthermore, the target-modified EVs clothing retains outstanding metformin loading capacity while endowing enhanced biological barrier penetration. A noticeably durable innate immune activation of NK cells was triggered with this nanoplatform via the cGAS-STING pathway. The enhanced immunocompetence was verified on distal metastasis and in-situ recurrence model in vivo, This work paved a new path for synergistic and robust innate immunity in clinical cancer treatment.

Exosomal non-coding RNAs in glioma progression: insights into tumor microenvironment dynamics and therapeutic implications

Gliomas are the most common and deadly types of brain tumors, known for their extensive genetic and epigenetic variability, which poses considerable challenges for pharmacological treatment. Glioma heterogeneity is also related to their intricate and dynamic tumor microenvironment (TME), which comprises a diverse array of cell types, including immune cells, vascular cells, glial cells, and neural precursors, collectively influencing tumor behavior and progression. A pivotal aspect of this intercellular communication relies on the exchange of extracellular vesicles (EVs), which contain and transfer complex molecular cargoes typical of their cells of origin, such as proteins, lipids, carbohydrates, metabolites, and non-coding RNAs (ncRNAs), that encompass microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs). Glioma cells actively release EVs loaded with specific ncRNAs that can target genes and other ncRNAs in recipient cells residing within the TME. Among these recipient cells, prominent players include tumor-associated macrophages and microglia (TAMs), non-neoplastic astrocytes and endothelial cells. The intricate interplay between EVs derived from glioma cells and these recipient cells significantly contributes to the establishment of a tumor-permissive microenvironment, promoting tumor cell proliferation, migration, angiogenesis, and invasion, by targeting various downstream pathways. This review critically examines the current understanding of the intricate interplay between glioma, exosomal ncRNAs, and various components of the glioma TME. By shedding light on the roles of ncRNAs in mediating intercellular communication, this review underscores their significance in orchestrating TME transformation and highlights their potential as novel therapeutic targets for effectively tackling glioma progression.

Transcriptome profiling of patient-derived tumor xenografts suggests novel extracellular matrix-related signatures for gastric cancer prognosis prediction

BACKGROUND

A major obstacle to the development of personalized therapies for gastric cancer (GC) is the prevalent heterogeneity at the intra-tumor, intra-patient, and inter-patient levels. Although the pathological stage and histological subtype diagnosis can approximately predict prognosis, GC heterogeneity is rarely considered. The extracellular matrix (ECM), a major component of the tumor microenvironment (TME), extensively interacts with tumor and immune cells, providing a possible proxy to investigate GC heterogeneity. However, ECM consists of numerous protein components, and there are no suitable models to screen ECM-related genes contributing to tumor growth and prognosis. We constructed patient-derived tumor xenograft (PDTX) models to obtain robust ECM-related transcriptomic signatures to improve GC prognosis prediction and therapy design.

METHODS

One hundred twenty two primary GC tumor tissues were collected to construct PDTX models. The tumorigenesis rate and its relationship with GC prognosis were investigated. Transcriptome profiling was performed for PDTX-originating tumors, and least absolute shrinkage and selection operator (LASSO) Cox regression analysis was applied to extract prognostic ECM signatures and establish PDTX tumorigenicity-related gene (PTG) scores. The predictive ability of the PTG score was validated using two independent cohorts. Finally, we combined PTG score, age, and pathological stage information to establish a robust nomogram for GC prognosis prediction.

RESULTS

We found that PDTX tumorigenicity indicated a poor prognosis in patients with GC, even at the same pathological stage. Transcriptome profiling of PDTX-originating GC tissues and corresponding normal controls identified 383 differentially expressed genes, with enrichment of ECM-related genes. A robust prognosis prediction model using the PTG score showed robust performance in two validation cohorts. A high PTG score was associated with elevated M2 polarized macrophage and cancer-associated fibroblast infiltration. Finally, combining the PTG score with age and TNM stage resulted in a more effective prognostic model than age or TNM stage alone.

CONCLUSIONS

We found that ECM-related signatures may contribute to PDTX tumorigenesis and indicate a poor prognosis in GC. A feasible survival prediction model was built based on the PTG score, which was associated with immune cell infiltration. Together with patient ages and pathological TNM stages, PTG score could be a new approach for GC prognosis prediction.

Recent Trends in the Use of Small Extracellular Vesicles as Optimal Drug Delivery Vehicles in Oncology

Small extracellular vesicles (sEVs) are produced by most cells and play an important role in cell-to-cell communication and maintaining cellular homeostasis. Their ability to transfer biological cargo to target cells makes them a promising tool for cancer drug delivery. Advances in sEV engineering, EV mimetics, and ligand-directed targeting have improved the efficacy of anticancer drug delivery and functionality. EV-based RNA interference and hybrid miRNA transfer have also been extensively used in various preclinical cancer models. Despite these developments, gaps still exist in our understanding of using sEVs to treat solid tumor malignancies effectively. This article provides an overview of the last five years of sEV research and its current status for the efficient and targeted elimination of cancer cells, which could advance cancer research and bring sEV formulations into clinical use.

Extracellular vesicles: a rising star for therapeutics and drug delivery

Extracellular vesicles (EVs) are nano-sized, natural, cell-derived vesicles that contain the same nucleic acids, proteins, and lipids as their source cells. Thus, they can serve as natural carriers for therapeutic agents and drugs, and have many advantages over conventional nanocarriers, including their low immunogenicity, good biocompatibility, natural blood-brain barrier penetration, and capacity for gene delivery. This review first introduces the classification of EVs and then discusses several currently popular methods for isolating and purifying EVs, EVs-mediated drug delivery, and the functionalization of EVs as carriers. Thereby, it provides new avenues for the development of EVs-based therapeutic strategies in different fields of medicine. Finally, it highlights some challenges and future perspectives with regard to the clinical application of EVs.

Functionalisation of extracellular vesicles with cyclic-RGDyC potentially for glioblastoma targeted intracellular drug delivery

With the intrinsic ability to cross the blood-brain barrier, small extracellular vesicles (sEVs) hold promise as endogenous brain-targeted drug delivery nano-platforms for glioblastoma (GBM) treatment. To increase GBM targetability, this study aimed to functionalise sEVs with cyclic arginine-glycine-aspartic acid-tyrosine-cysteine (cRGDyC), a ligand for integrin (α_vβ₃) that is overexpressed in GBM cells. Firstly, the intrinsic cellular uptake of sEVs derived from GBM U87 and pancreatic cancer MIA PaCa-2 cells was investigated on the donor cells. To obtain functionalised sEVs (cRGDyC-sEVs), DSPE-mPEG₂₀₀₀-maleimide was incubated with the selected (U87) sEVs, and cRGDyC was subsequently conjugated to the maleimide groups via a thiol-maleimide coupling reaction. The GBM cell targetability and intracellular trafficking of cRGDyC-sEVs were evaluated on U87 cells by fluorescence and confocal microscopy, using unmodified sEVs as a reference. The cytotoxicity of doxorubicin-loaded vesicles (Dox@sEVs, Dox@cRGDyC-sEVs) was compared with a standard liposome formulation (Dox@Liposomes) and free Dox. Both U87 and MIA PaCa-2 cell-derived sEVs displayed tropism with the former being >4.9-fold more efficient to be internalised into U87. Therefore, the U87-derived sEVs were chosen for GBM-targeting. Approximately 4000 DSPE-mPEG₂₀₀₀-maleimide were inserted onto each sEV with cRGDyC conjugated to the maleimide group. The cell targetability of cRGDyC-sEVs to U87 cells improved 2.4-fold than natural sEVs. Despite their proneness to be colocalised with endosomes/lysosomes, both Dox@sEVs and Dox@cRGDyC-sEVs showed superior cytotoxicity to U87 GBM cells compared to Dox@Liposomes, particularly Dox@cRGDyC-sEVs. Overall, U87-derived sEVs were successufully conjugated with cRGDyC via a PEG linker, and cRGDyC-sEVs were demonstrated to be a potnetial integrin-targeting drug delivery vehicle for GBM treatment. Graphic abstract.

Extracellular Vesicles as Therapeutic Resources in the Clinical Environment

The native role of extracellular vesicles (EVs) in mediating the transfer of biomolecules between cells has raised the possibility to use them as therapeutic vehicles. The development of therapies based on EVs is now expanding rapidly; here we will describe the current knowledge on different key points regarding the use of EVs in a clinical setting. These points are related to cell sources of EVs, isolation, storage, and delivery methods, as well as modifications to the releasing cells for improved production of EVs. Finally, we will depict the application of EVs therapies in clinical trials, considering the impact of the COVID-19 pandemic on the development of these therapies, pointing out that although it is a promising therapy for human diseases, we are still in the initial phase of its application to patients.

Human macrophage-engineered vesicles for utilization in ovarian cancer treatment

Background

Ovarian cancer is a deadly female malignancy with a high rate of recurrent and chemotherapy-resistant disease. Tumor-associated macrophages (TAMs) are a significant component of the tumor microenvironment and include high levels of M2-protumor macrophages that promote chemoresistance and metastatic spread. M2 macrophages can be converted to M1 anti-tumor macrophages, representing a novel therapeutic approach. Vesicles engineered from M1 macrophages (MEVs) are a novel method for converting M2 macrophages to M1 phenotype-like macrophages.

Methods

Macrophages were isolated and cultured from human peripheral blood mononuclear cells. Macrophages were stimulated to M1 or M2 phenotypes utilizing LPS/IFN-γ and IL-4/IL-13, respectively. M1 MEVs were generated with nitrogen cavitation and ultracentrifugation. Co-culture of ovarian cancer cells with macrophages and M1 MEVs was followed by cytokine, PCR, and cell viability analysis. Murine macrophage cell line, RAW264.7 cells were cultured and used to generate M1 MEVs for use in ovarian cancer xenograft models.

Results

M1 MEVs can effectively convert M2 macrophages to an M1-like state both in isolation and when co-cultured with ovarian cancer cells in vitro, resulting in a reduced ovarian cancer cell viability. Additionally, RAW264.7 M1 MEVs can localize to ovarian cancer tumor xenografts in mice.

Conclusion

Human M1 MEVs can repolarize M2 macrophages to a M1 state and have anti-cancer activity against ovarian cancer cell lines. RAW264.7 M1 MEVs localize to tumor xenografts in vivo murine models.

Extracellular Vesicles and Viruses: Two Intertwined Entities

Viruses share many attributes in common with extracellular vesicles (EVs). The cellular machinery that is used for EV production, packaging of substrates and secretion is also commonly manipulated by viruses for replication, assembly and egress. Viruses can increase EV production or manipulate EVs to spread their own genetic material or proteins, while EVs can play a key role in regulating viral infections by transporting immunomodulatory molecules and viral antigens to initiate antiviral immune responses. Ultimately, the interactions between EVs and viruses are highly interconnected, which has led to interesting discoveries in their associated roles in the progression of different diseases, as well as the new promise of combinational therapeutics. In this review, we summarize the relationships between viruses and EVs and discuss major developments from the past five years in the engineering of virus-EV therapies.

Extracellular Vesicles as Drug Targets and Delivery Vehicles for Cancer Therapy

Extracellular vesicles (EVs) are particles that are released from cells into the extracellular space both under pathological and normal conditions. It is now well established that cancer cells secrete more EVs compared to non-cancerous cells and that, captivatingly, several proteins that are involved in EV biogenesis and secretion are upregulated in various tumours. Recent studies have revealed that EVs facilitate the interaction between cancer cells and their microenvironment and play a substantial role in the growth of tumours. As EVs are involved in several aspects of cancer progression including angiogenesis, organotropism, pre-metastatic niche formation, fostering of metastasis, and chemoresistance, inhibiting the release of EVs from cancer and the surrounding tumour microenvironment cells has been proposed as an ideal strategy to treat cancer and associated paraneoplastic syndromes. Lately, EVs have shown immense benefits in preclinical settings as a novel drug delivery vehicle. This review provides a brief overview of the role of EVs in various hallmarks of cancer, focusing on (i) strategies to treat cancer by therapeutically targeting the release of tumour-derived EVs and (ii) EVs as valuable drug delivery vehicles. Furthermore, we also outline the drawbacks of the existing anti-cancer treatments and the future prospective of EV-based therapeutics.

Amplification of anticancer efficacy by co-delivery of doxorubicin and lonidamine with extracellular vesicles

Chemotherapy is commonly used for the treatment of lung cancer, but strong side effects and low treatment efficacy limit its clinical application. Here, extracellular vesicles (EVs) as natural drug delivery carriers were used to load conventional anticancer drug doxorubicin (DOX) and a chemosensitizer lonidamine (LND). Two types of EVs with different sizes (16k EVs and 120k EVs) were prepared using different centrifugation forces. We found that co-delivery of DOX and LND with both EVs enhanced the cytotoxicity and reduced the dose of the anticancer drug significantly in vitro. Effective delivery of anti-cancer drugs to cancer cells was achieved by direct fusion of EVs with the plasma membrane of cancer cells. On the other hand, DOX and LND inhibited cancer cell proliferation by increasing DNA damage, suppressing ATP production, and accelerating ROS generation synergistically. DOX and LND loaded EVs were also applied to the mouse lung cancer model and exhibited significant anticancer activity. In vivo study showed that smaller EVs exhibited higher anticancer efficiency. In conclusion, the co-delivery of the anticancer drug and the chemosensitizer with EVs may have potential clinical applications for cancer therapy.

In Vivo Imaging for the Visualization of Extracellular Vesicle-Based Tumor Therapy

Extracellular vesicles (EVs) exhibiting versatile biological functions provide promising prospects as natural therapeutic agents and drug delivery vehicles. For future clinical translation, revealing the fate of EVs in vivo, especially their accumulation at lesion sites, is very important. The continuous development of in vivo imaging technology has made it possible to track the real-time distribution of EVs. This article reviews the applications of mammal-, plant-, and bacteria-derived EVs in tumor therapy, the labeling methods of EVs for in vivo imaging, the advantages and disadvantages of different imaging techniques, and possible improvements for future work.

Design and fabrication of chitosan-based AIE active micelles for bioimaging and intelligent delivery of paclitaxel

In this study, cetyl 4-formylbenzoate alkyl and 4-(2-hydroxyethoxy) benzophenonesalicylaldazide modified biotinylated chitosan (CS-BT-HBS-CB) featured with aggregation-induced emission (AIE) characteristic, active tumor-targeting ability and pH-responsive drug release property was designed and synthesized. The polymer was fabricated by introducing hydrophobic segment, tumor targeting ligand, acid-sensitive bond and AIE fluorophore to the backbone of chitosan. Due to its amphiphilicity, the polymer could self-assemble into micelles and encapsulate paclitaxel (PTX) to form PTX-loaded CS-BT-HBS-CB micelles. The mean size of the micelles was 167 nm, which was beneficial to the EPR effect. Moreover, with the help of above functional groups, the micelles exhibited excellent AIE effect, triggered drug release behavior by acidic condition, selective internalization by MCF-7 cells and excellent cellular imaging capability. In vivo studies revealed that the PTX-loaded CS-BT-HBS-CB micelles could enhance the antitumor efficacy with low systemic toxicity. This micellar system would be a potential candidate for cancer therapy and bioimaging.

Cell-derived extracellular vesicles for CRISPR/Cas9 delivery: engineering strategies for cargo packaging and loading

Genome editing technology has emerged as a potential therapeutic tool for treating incurable diseases. In particular, the discovery of clustered regularly interspaced short palindromic repeats (CRISPR)/Cas systems and the design of single-guide RNAs (sgRNAs) have revolutionized genome editing applications. Unfortunately, compared with the rapid development of gene-editing tools, the progress in the development of delivery technologies is lagging behind and thus limiting the clinical application of genome editing. To overcome these limitations, researchers have investigated various delivery systems, including viral and non-viral vectors for delivering CRISPR/Cas and sgRNA complexes. As natural endogenous nanocarriers, extracellular vesicles (EVs) present advantages of biocompatibility, low immunogenicity, stability, and high permeability, making them one of the most promising drug delivery vehicles. This review provides an overview of the fundamental mechanisms of EVs from the aspects of biogenesis, trafficking, cargo delivery, and function as nanotherapeutic agents. We also summarize the latest trends in EV-based CRISPR/Cas delivery systems and discuss the prospects for future development. In particular, we put our emphasis on the state-of-the-art engineering strategies to realize efficient cargo packaging and loading. Altogether, EVs hold promise in bridging genome editing in the laboratory and clinical applications of gene therapies by providing a safe, effective, and targeted delivery vehicle.

Tumor suppressive role of microRNA-139-5p in bone marrow mesenchymal stem cells-derived extracellular vesicles in bladder cancer through regulation of the KIF3A/p21 axis

The emerging roles of extracellular vesicles (EVs) in bladder cancer have recently been identified. This study aims to elucidate the role of microRNA-139-5p (miR-139-5p) shuttled by bone marrow mesenchymal stem cells (BMSCs)-derived EVs (BMSCs-EVs) in bladder cancer, with the possible mechanism explored. Expression of miR-139-5p and KIF3A was tested, followed by an analysis of their correlation. EVs were isolated from BMSCs and co-cultured with T24 or BOY-12E cells with miR-139-5p mimic/inhibitor, oe-KIF3A, and/or si-p21 transfected to study the roles of miR-139-5p/KIF3A/p21 in bladder cancer cell functions. A nude mouse model of subcutaneous xenograft tumor was constructed to detect the effect of miR-139-5p in BMSCs-EVs on the tumorigenesis and lung metastasis of bladder cancer cells in vivo. It was identified that miR-139-5p was highly expressed in BMSCs-EVs, but poorly expressed in bladder cancer. BMSCs-EVs transferred miR-139-5p into bladder cancer cells where miR-139-5p inhibited the malignant features of bladder cancer cells in vitro. miR-139-5p in BMSCs-EVs targeted KIF3A and inhibited the expression of KIF3A, thereby activating p21. miR-139-5p in BMSCs-EVs arrested the tumorigenesis and lung metastasis of bladder cancer cells in vivo by modulation of the KIF3A/p21 axis. Altogether, BMSCs-EVs carried miR-139-5p targeted KIF3A to activate p21, thus delaying the occurrence of bladder cancer.

Extracellular vesicles deliver sodium iodide symporter protein and promote cancer cell radioiodine therapy

Extracellular vesicles (EVs) are a promising carrier for various cargos with antitumor effects, but their capacity to transfer the ability to transport radioiodine for cancer theranostics remains unexplored. Herein, we tested the hypothesis that EVs can be loaded with the sodium iodide symporter (NIS) protein and efficiently deliver the payload to recipient cancer cells to facilitate radioiodine uptake. The results revealed that donor cells either transduced with an adenoviral vector for transient expression or engineered for stable overexpression secreted EVs that contained substantial amounts of NIS protein but not NIS mRNA. Huh7 liver cancer cells treated with EVs secreted from each of the donor cell types showed significantly increased plasma membrane NIS protein, indicating efficient payload delivery. Furthermore, intact function of the delivered NIS protein was confirmed by significantly increased radioiodine transport in recipient cancer cells that peaked at 48 h. Importantly, NIS protein delivered by EVs significantly enhanced the antitumor effects of ¹³¹I radiotherapy. These results reveal that EVs are a promising vehicle to deliver NIS protein to cancer cells in sufficient amounts for radioiodine-based theranostics.

Recent progresses in exosome-based systems for targeted drug delivery to the brain

Despite the multiple ongoing and novel initiatives for developing brain-targeted drug delivery systems, insurmountable obstacles remain. A perfect drug delivery device that can bypass the brain-blood barrier and boost therapeutic efficacy is urgently needed for clinical applications. Exosomes hold unrivaled benefits as a drug delivery vehicle for treating brain diseases due to their endogenous and innate attributes. Unique properties, such as the ability to penetrate physical barriers, biocompatibility, innate targeting features, ability to leverage natural intracellular trafficking pathways, favored tumor homing, and stability, make exosomes suitable for brain-targeted drug delivery. Herein, we provide an overview of recent exosome-based drug delivery nanoplatforms and discuss how these inherent vesicles can be used to deliver therapeutic agents to the brain to cure neurodegenerative diseases, brain tumors, and other brain disorders. Moreover, we review the current roadblocks associated with exosomes and other brain-targeted drug delivery systems and discuss future directions for achieving successful therapy outcomes.

Extracellular vesicle-based macromolecule delivery systems in cancer immunotherapy

Great attention has been paid to the impressive role the macromolecules played in cancer immunotherapy, however, the applications were largely limited by their poor circulation stability, low cellular uptake efficiency, and off-target effects. As an important messenger of intercellular communication, extracellular vesicles (EVs) exhibit unique advantages in macromolecule delivery compared to traditional synthetic carriers, offering new possibilities for modern drug delivery. These naturally derived carriers can achieve stable, efficient, and selective delivery of macromolecules and improve the efficacy and potentiality of macromolecular drugs in cancer immunotherapy. This review provides a brief overview of the unique features of EVs related to macromolecule delivery, the strategies and recent advances of using EVs as macromolecule delivery carriers in cancer immunotherapy.

Extracellular Vesicles and Hepatocellular Carcinoma: Opportunities and Challenges

The incidence of hepatocellular carcinoma (HCC) is increasing worldwide. Extracellular vesicles (EVs) contain sufficient bioactive substances and are carriers of intercellular information exchange, as well as delivery vehicles for nucleic acids, proteins and drugs. Although EVs show great potential for the treatment of HCC and their role in HCC progression has been extensively studied, there are still many challenges such as time-consuming extraction, difficult storage, easy contamination, and low drug loading rate. We focus on the biogenesis, morphological characteristics, isolation and extraction of EVs and their significance in the progression of HCC, tumor invasion, immune escape and cancer therapy for a review. EVs may be effective biomarkers for molecular diagnosis of HCC and new targets for tumor-targeted therapy.

Extracellular Vesicles in Cardiovascular Diseases: Diagnosis and Therapy

Cardiovascular diseases (CVDs) are the leading cause of global mortality. Therapy of CVDs is still a great challenge since many advanced therapies have been developed. Multiple cell types produce nano-sized extracellular vesicles (EVs), including cardiovascular system-related cells and stem cells. Compelling evidence reveals that EVs are associated with the pathophysiological processes of CVDs. Recently researches focus on the clinical transformation in EVs-based diagnosis, prognosis, therapies, and drug delivery systems. In this review, we firstly discuss the current knowledge about the biophysical properties and biological components of EVs. Secondly, we will focus on the functions of EVs on CVDs, and outline the latest advances of EVs as prognostic and diagnostic biomarkers, and therapeutic agents. Finally, we will introduce the specific application of EVs as a novel drug delivery system and its application in CVDs therapy. Specific attention will be paid to summarize the perspectives, challenges, and applications on EVs’ clinical and industrial transformation.

Multifunctional Nanosystems Powered Photodynamic Immunotherapy

Photodynamic Therapy (PDT) with the intrinsic advantages including non-invasiveness, spatiotemporal selectivity, low side-effects, and immune activation ability has been clinically approved for the treatment of head and neck cancer, esophageal cancer, pancreatic cancer, prostate cancer, and esophageal squamous cell carcinoma. Nevertheless, the PDT is only a strategy for local control of primary tumor, that it is hard to remove the residual tumor cells and inhibit the tumor metastasis. Recently, various smart nanomedicine-based strategies are developed to overcome the barriers of traditional PDT including the drawbacks of traditional photosensitizers, limited tissue penetrability of light, inefficient induction of tumor cell death and tumor resistance to the therapy. More notably, a growing number of studies have focused on improving the therapeutic efficiency by eliciting host immune system with versatile nanoplatforms, which heralds a broader clinical application prospect of PDT in the future. Herein, the pathways of PDT induced-tumor destruction, especially the host immune response is summarized, and focusing on the recent progress of nanosystems-enhanced PDT through eliciting innate immunity and adaptive immunity. We expect it will provide some insights for conquering the drawbacks current PDT and expand the range of clinical application through this review.

Near-infrared analysis of nanofibrillated cellulose aerogel manufacturing

Biomaterial aerogel fabrication by freeze-drying must be further improved to reduce the costs of lengthy freeze-drying cycles and to avoid the formation of spongy cryogels and collapse of the aerogel structures. Residual water content is a critical quality attribute of the freeze-dried product, which can be monitored in-line with near-infrared (NIR) spectroscopy. Predictive models of NIR have not been previously applied for biomaterials and the models were mostly focused on the prediction of only one formulation at a time. We recorded NIR spectra of different nanofibrillated cellulose (NFC) hydrogel formulations during the secondary drying and set up a partial least square regression model to predict their residual water contents. The model can be generalized to measure residual water of formulations with different NFC concentrations and the excipients, and the NFC fiber concentrations and excipients can be separated with the principal component analysis. Our results provide valuable information about the freeze-drying of biomaterials and aerogel fabrication, and how NIR spectroscopy can be utilized in the optimization of residual water content.

The Landscape of Nanovectors for Modulation in Cancer Immunotherapy

Immunotherapy represents a promising strategy for the treatment of cancer, which functions via the reprogramming and activation of antitumor immunity. However, adverse events resulting from immunotherapy that are related to the low specificity of tumor cell-targeting represent a limitation of immunotherapy's efficacy. The potential of nanotechnologies is represented by the possibilities of immunotherapeutical agents being carried by nanoparticles with various material types, shapes, sizes, coated ligands, associated loading methods, hydrophilicities, elasticities, and biocompatibilities. In this review, the principal types of nanovectors (nanopharmaceutics and bioinspired nanoparticles) are summarized along with the shortcomings in nanoparticle delivery and the main factors that modulate efficacy (the EPR effect, protein coronas, and microbiota). The mechanisms by which nanovectors can target cancer cells, the tumor immune microenvironment (TIME), and the peripheral immune system are also presented. A possible mathematical model for the cellular communication mechanisms related to exosomes as nanocarriers is proposed.

Pioneer Role of Extracellular Vesicles as Modulators of Cancer Initiation in Progression, Drug Therapy, and Vaccine Prospects

Cancer is one of the leading diseases, causing deaths worldwide. Nearly 10 million deaths were reported in 2020 due to cancer alone. Several factors are involved in cancer progressions, such as lifestyle and genetic characteristics. According to a recent report, extracellular vesicles (EVs) are involved in cancer initiation, progression, and therapy failure. EVs can play a major role in intracellular communication, the maintenance of tissue homeostasis, and pathogenesis in several types of diseases. In a healthy person, EVs carry different cargoes, such as miRNA, lncRNA etc., to help other body functions. On the other hand, the same EV in a tumor microenvironment carries cargoes such as miRNA, lncRNA, etc., to initiate or help cancer progression at various stages. These stages may include the proliferation of cells and escape from apoptosis, angiogenesis, cell invasion, and metastasis, reprogramming energy metabolism, evasion of the immune response, and transfer of mutations. Tumor-derived EVs manipulate by altering normal functions of the body and affect the epigenetics of normal cells by limiting the genetic makeup through transferring mutations, histone modifications, etc. Tumor-derived EVs also pose therapy resistance through transferring drug efflux pumps and posing multiple drug resistances. Such EVs can also help as biomarkers for different cancer types and stages, which ultimately help with cancer diagnosis at early stages. In this review, we will shed light on EVs' role in performing normal functions of the body and their position in different hallmarks of cancer, in altering the genetics of a normal cell in a tumor microenvironment, and their role in therapy resistance, as well as the importance of EVs as diagnostic tools.

Cell-Derived Biogenetic Gold Nanoparticles for Sensitizing Radiotherapy and Boosting Immune Response against Cancer

The biosynthesis of nanomedicine has gained enormous attention and exhibited promising prospects, while the underlying mechanism and advantage remain not fully understood. Here, a cell-reactor based on tumor cells is developed to obtain biogenetic gold nanoparticles (Au@MC38) for sensitizing radiotherapy and boosting immune responses. It demonstrates that the intracellular biomineralization and exocytosis process of Au@MC38 can be regulated by the cellular metabolites level and other factors, such as glutathione and reactive oxygen species (ROS), autophagy, and UV irradiation. The elucidation of mechanisms may promote the understanding of interaction principles between nanoparticles and biosystems in the process of biosynthesis. Combined with radiotherapy, Au@MC38 strengthens the radiation-induced DNA damage and ROS generation, thus aggravating cell apoptosis and necrosis. Benefiting from homologous targeting and transcytosis effect, Au@MC38 demonstrates good tumor distribution. Local radiation-induced immunogenic cell death initiates an effective immune response. Especially, CD8a⁺ dendritic cells are significantly increased in mice that received combinatorial treatment. This radio-sensitization strategy has demonstrated the effective inhibition on primary and metastatic tumors, and achieved satisfactory survival benefit in combinatorial with immune checkpoint blockade. Thus, this bio-inspired synthetic strategy may impulse the development of biosynthesis and its therapeutic applications, contributing to a non-invasive and efficient modality for nanomedicine exploitation.

Promises of phytochemical based nano drug delivery systems in the management of cancer

Cancer is the leading cause of human disease and death worldwide, accounting for 7.6 million deaths per year and projected to reach 13.1 million by 2030. Many phytochemicals included in traditional medicine have been utilized in the management of cancer. Conventional chemotherapy is generally known to be the most effective treatment of metastatic cancer but these cancerous cells might grow resistant to numerous anticancer drugs over time that resulting in treatment failure. This review tried to portray the advancement in the anticancer and chemopreventive effects of several phytochemicals and some of its members encapsulated in the nano-based delivery system of the drug. It comprises the issue associated with limited use of each phytoconstituents in human cancer treatment are discussed, and the benefits of entrapment into nanocarriers are evaluated in terms of drug loading efficiency, nanocarrier size, release profile of the drug, and in vitro and/or in vivo research and treatment testing, such as cytotoxicity assays and cell inhibition/viability.

Application of extracellular vesicles in the diagnosis and treatment of prostate cancer: Implications for clinical practice

Extracellular vesicles (EV) are cell-derived lipid bilayer-delimited structures providing an important means of intercellular communication. Recent studies have shown that EV, particularly exosomes and large-oncosomes contain miRNA and proteins crucial in prostate cancer (PCa) progression, metastasis and treatment resistance. This includes not just EV released from PCa cells, but also from other cells in the tumor microenvironment. PCa patient derived EV have a unique composition compared to healthy and benign prostatic diseases. As such, EV show promise as diagnostic liquid biopsy biomarkers, both as an adjunct and alternative to the invasive current gold-standard. EV could also be utilized to stratify patients' risk and predict response to hormonal, chemo, immune- and targeted therapy, which will direct future treatment decisions in PCa. We present a summary of the current evidence on the role of EV in PCa and the application of EV in PCa diagnosis and treatment to optimize patient outcomes.

Dually targeted bioinspired nanovesicle delays advanced prostate cancer tumour growth in vivo

Prostate cancer (PC) is second-leading cancer in men, with limited treatment options available for men with advanced and metastatic PC. Prostate-specific antigen (PSA) and prostate-specific membrane antigen (PSMA) have been exploited as therapeutic targets in PC due to their upregulation in the advanced stages of the disease. To date, several PSA- and PSMA-activatable prodrugs have been developed to reduce the systemic toxicity of existing chemotherapeutics. Bioinspired nanovesicles have been exploited in drug delivery, offering prolonged drug blood circulation and higher tumour accumulation. For the first time, this study describes the engineering of dually targeted PSA/PSMA nanovesicles for advanced PC. PSMA-targeted bioinspired hybrids were prepared by hydrating a lipid film with anti-PSMA-U937 cell membranes and DOX-PSA prodrug, followed by extrusion. The bioinspired hybrids were characterised using dynamic light scattering, transmission electron microscopy, Dot blot, flow cytometry and Western blot. Cellular binding and toxicity studies in PC cancer cell lines were carried out using flow cytometry, confocal microscopy, and resazurin assay. Finally, tumour targeting and therapeutic efficacy studies were performed in solid and metastatic C4-2B-tumor-bearing mice. Interestingly, our PSMA-targeted hybrids demonstrated high cell uptake in PSMA-expressing cells with significant accumulation in solid and metastatic C4-2B tumour tissues following intravenous administration. More promisingly, our dually targeted PSA/PSMA hybrid significantly slowed down the C4-2B tumour growth in vivo, compared to free DOX-PSA and non-targeted PSA-hybrid. Our PSA/PSMA bioinspired hybrid could offer a highly selective treatment for advanced PC with lower side effects. STATEMENT OF SIGNIFICANCE: This study investigates a new approach to treat prostate cancer using dually targeted bioinspired nanovesicle . Our bioinspired vesicles are made mainly of a human blood cell membrane with a ligand recognising a specific marker (PSMA) on the surface of the prostate cancer cells. The present work describes the successful loading of a doxorubicin prodrug linked to a PSA- activatable peptide into these targeted bioinspired nanovesicle , where the active PSA enzyme presents in these cells converts the drug to its active form. Our dually targeted PSA/PSMA hybrid vesicles has successfully improved site-specific prodrug delivery to tackle advanced prostate cancer, offering a novel and effective prostate cancer treatment.

Zebrafish as a preclinical model for Extracellular Vesicle-based therapeutic development

Extracellular Vesicles (EVs) are released during various pathophysiological processes and reflect the state of their cell of origin. Once released, they can propagate through biological fluids, target cells, deliver their content and elicit functional responses. These specific features would allow their harnessing as biomarkers, drug nano-vehicles and therapeutic intrinsic modulators. However, the further development of their potential therapeutic application is hampered by the lack of knowledge about how EVs behave in vivo. Recent advances in the field of imaging EVs in vivo now allow live-tracking of endogenous and exogenous EV in various model organisms at high spatiotemporal resolution to define their distribution, half-life and fate. This review highlights current imaging tools available to image EVs in vivo and how live imaging especially in the zebrafish embryo can bring further insights into the characterization of EVs dynamics, biodistribution and functions to potentiate their development for therapeutic applications.

Extracellular vesicles as a next-generation drug delivery platform

Extracellular-vesicle-based cell-to-cell communication is conserved across all kingdoms of life. There is compelling evidence that extracellular vesicles are involved in major (patho)physiological processes, including cellular homoeostasis, infection propagation, cancer development and cardiovascular diseases. Various studies suggest that extracellular vesicles have several advantages over conventional synthetic carriers, opening new frontiers for modern drug delivery. Despite extensive research, clinical translation of extracellular-vesicle-based therapies remains challenging. Here, we discuss the uniqueness of extracellular vesicles along with critical design and development steps required to utilize their full potential as drug carriers, including loading methods, in-depth characterization and large-scale manufacturing. We compare the prospects of extracellular vesicles with those of the well established liposomes and provide guidelines to direct the process of developing vesicle-based drug delivery systems.

Exosomes as Naturally Occurring Vehicles for Delivery of Biopharmaceuticals: Insights from Drug Delivery to Clinical Perspectives

Exosomes as nanosized vesicles are emerging as drug delivery systems for therapeutics owing to their natural origin, their ability to mediate intercellular communication, and their potential to encapsulate various biological molecules such as proteins and nucleic acids within the lipid bilayer membrane or in the lumen. Exosomes contain endogenous components (proteins, lipids, RNA) that could be used to deliver cargoes to target cells, offering an opportunity to diagnose and treat various diseases. Owing to their ability to travel safely in extracellular fluid and to transport cargoes to target cells with high efficacy, exosomes offer enhanced delivery of cargoes in vivo. However, several challenges related to the stabilization of the exosomes, the production of sufficient amounts of exosomes with safety and efficacy, the efficient loading of drugs into exosomes, the clearance of exosomes from circulation, and the transition from the bench scale to clinical production may limit their development and clinical use. For the clinical use of exosomes, it is important to understand the molecular mechanisms behind the transport and function of exosome vesicles. This review exploits techniques related to the isolation and characterization of exosomes and their drug delivery potential to enhance the therapeutic outcome and stabilization methods. Further, routes of administration, clinical trials, and regulatory aspects of exosomes will be discussed in this review.

Harnessing the therapeutic potential of extracellular vesicles for cancer treatment

Cancer therapeutic strategies include surgeries, radiotherapy, chemotherapy, targeted therapy and immunotherapies. However, current cancer treatment still faces challenges such as postoperative residuals, postoperative recurrence, chemoradiotherapy resistance and lack of drugs with high specificity, due to the complexity of the cancer environment. Extracellular vesicles (EVs) are lipid-capsuled membrane vesicles secreted from cells, communicating vital messages between cells and regarding function in tumorigenesis and metastasis. Investigation of compositions and functions of EVs may open unprecedented, promising avenues for cancer therapeutics. This review brings new perspectives from both researchers and clinicians in the EV field, emphasizing the ties between basic research and ongoing clinical trials. In sum, our review summarizes the roles EVs play in cancer therapy, ranging from mechanisms to applications in cancer treatment. In particular, it focuses on their therapeutic potential with an eye toward clinical relevance.

The role and application of small extracellular vesicles in gastric cancer

Gastric cancer (GC) is a common tumour that affects humans worldwide, is highly malignant and has a poor prognosis. Small extracellular vesicles (sEVs), especially exosomes, are nanoscale vesicles released by various cells that deliver bioactive molecules to recipient cells, affecting their biological characteristics, changing the tumour microenvironment and producing long-distance effects. In recent years, many studies have clarified the mechanisms by which sEVs function with regard to the initiation, progression, angiogenesis, metastasis and chemoresistance of GC. These molecules can function as mediators of cell-cell communication in the tumour microenvironment and might affect the efficacy of immunotherapy. Due to their unique physiochemical characteristics, sEVs show potential as effective antitumour vaccines as well as drug carriers. In this review, we summarize the roles of sEVs in GC and highlight the clinical application prospects in the future.

Simultaneous imaging of cancer biomarkers in live cells based on DNA-engineered exosomes

Cancer biomarkers are directly related to the development of cancers. Noninvasive identification of the location and expression levels of these biomarkers in live cancer cells offers great potential for accurate early-stage cancer diagnosis and cancer metastasis monitoring. Herein, we propose a DNA-engineered exosome (DNA-Exo) nanoplatform to image dual cancer biomarkers at the single-cell level, in which DNA probes were modified with the cholesterol group to facilely anchor on the exosomal membrane through hydrophobic interaction. Fluorophore-labeled DNA aptamer and hairpin probes targeting two kinds of cancer biomarkers of transmembrane glycoprotein mucin 1 (MUC1) and cytoplasmic microRNA-21 (miR-21), respectively, were employed for convenient dual-fluorescence imaging of cancer cells. The cellular uptake of DNA-Exos induced the specific recognition of MUC1 and miR-21, allowing the acquisition of the expression levels and spatial distributions of these two biomarkers in three tested cell lines. Our work demonstrated that the proposed DNA-Exos with designable functions have the capacity to visually discriminate different cell types based on the specific recognition of analytes.

Recent Advancement and Technical Challenges in Developing Small Extracellular Vesicles for Cancer Drug Delivery

Extracellular vesicles (EVs) are a heterogeneous population of lipid bilayer membrane-enclosed vesicles and act like 'messages in a bottle' in cell-cell communication by transporting their cargoes to recipient cells. Small EVs (sEVs, < 200 nm) are highly researched recently and have been harnessed as novel delivery systems for the treatment of various diseases, including neurodegenerative disorders, cardiovascular diseases, and most importantly cancer primarily because of their non-immunogenicity, tissue penetration and cell-tropism. This review will first provide a comprehensive overview of sEVs regarding the current understanding on their properties, biogenesis, new classification by the ISEV, composition, as well as their roles in cancer development (thereby called "oncosomes"). The primary focus will be given to the current state of sEVs as natural nanocarriers for cancer drug delivery, the technologies and challenges involved in sEV isolation and characterization, therapeutic cargo loading, and surface modification to enhance tumor-targeting. We will also provide examples of sEV products under clinical trials. Furthermore, the current challenges as well as the advance in "sEV mimetics" to address some of the sEVs limitations is briefly discussed. We seek to advance our understanding of sEVs to unlock their full potential as superior drug delivery vehicles in cancer therapy.

An ultracentrifugation - hollow-fiber flow field-flow fractionation orthogonal approach for the purification and mapping of extracellular vesicle subtypes

In the course of their life span, cells release a multitude of different vesicles in the extracellular matrix (EVs), constitutively and/or upon stimulation, carrying signals either inside or on their membrane for intercellular communication. As a natural delivery tool, EVs present many desirable advantages, such as biocompatibility and low toxicity. However, due to the complex biogenesis of EVs and their high heterogeneity in size distribution and composition, the characterization and quantification of EVs and their subpopulations still represents an enticing analytical challenge. Centrifugation methods allow to obtain different subpopulations in an easy way from cell culture conditioned medium and biological fluids including plasma, amniotic fluid and urine, but they still present some drawbacks and limitations. An unsatisfactory isolation can limit their downstream analysis and lead to wrong conclusions regarding biological activities. Isolation and characterization of biologically relevant nanoparticles like EVs is crucial to investigate specific molecular and signaling patterns and requires new combined approaches. Our work was focused on HF5 (miniaturized, hollow-fiber flow field-flow fractionation), and its hyphenation to ultracentrifugation techniques, which are the most assessed techniques for vesicle isolation. We exploited model samples obtained from culture medium of murine myoblasts (C2C12), known to release different subsets of membrane-derived vesicles. Large and small EVs (LEVs and SEVs) were isolated by differential ultracentrifugation (UC). Through an HF5 method employing UV, fluorescence and multi-angle laser scattering as detectors, we characterized these subpopulations in terms of size, abundance and DNA/protein content; moreover, we showed that microvesicles tend to hyper-aggregate and partially release nucleic matter. The quali-quantitative information we obtained from the fractographic profiles was improved with respect to Nano Tracking Analysis (NTA) estimation. The SEV population was then further separated using density gradient centrifugation (DGC), and four fractions were submitted again to HF5-multidetection. This technique is based on a fully orthogonal principle, since F4 does not separate by density, and provided uncorrelated information for each of the fractions processed. The "second dimension" achieved with HF5 showed good promise in sorting particles with both different size and content, and allowed to identify the presence of fibrilloid nucleic matter. This analytical bidimensional approach proved to be effective for the characterization of highly complex biological samples such as mixtures of EVs and could provide purified fractions for further biological characterization.