Tumour-derived exosomes as antigen delivery carriers in dendritic cell-based immunotherapy for malignant mesothelioma

Unraveling the Connection: Extracellular Vesicles and Non-Small Cell Lung Cancer

Extracellular vesicles (EVs) are nanoscale lipid bilayer vesicles released during cell activation, cellular damage, or apoptosis. They carry nucleic acids, proteins, and lipids facilitating intercellular communication and activate signaling pathways in target cells. In non-small cell lung cancer (NSCLC), EVs may contribute to tumor growth and metastasis by modulating immune responses, facilitating epithelial-mesenchymal transition, and promoting angiogenesis, while potentially contributing to resistance to chemotherapy drugs. EVs in liquid biopsies serve as non-invasive biomarkers for early cancer detection and diagnosis. Due to their small size, inherent molecular transport properties, and excellent biocompatibility, EVs also act as natural drug delivery vehicles in NSCLC therapy.

Exosome-based anticancer vaccines: From Bench to bedside

Exosomes, a subset of extracellular vesicles, are released by all active cells and play a crucial role in intercellular communications. Exosomes could facilitate the transfer of various biologically active molecules, such as DNA, non-coding RNAs, and proteins, from donor to recipient cells, thereby participating in diverse biological and pathological processes. Besides, exosomes possess unique characteristics, including non-toxicity, low-immunogenicity, and stability within biological systems, rendering them highly advantageous for cancer drug development. Meanwhile, accumulating evidence suggests that exosomes originating from tumor cells and immune cells possess distinct composition profiles that play a direct role in anticancer immunotherapy. Of note, exosomes can transport their contents to specific cells, thereby exerting an impact on the phenotype and immune-regulatory functions of targeted cells. Therapeutic cancer vaccines, an emerging therapeutics of immunotherapy, could enhance antitumor immune responses by delivering a large number of tumor antigens, thereby augmenting the immune response against tumor cells. Therefore, the therapeutic rationale of cancer vaccines and exosome-based immunotherapy are almost similar to some extent, but some challenges have hindered their application in the clinical setting. Here, in this review, we first summarized the biogenesis, structure, compositions, and biological functions of exosomes. Then we described the roles of exosomes in cancer biology, particularly in tumor immunity. We also comprehensively reviewed current exosome-based anticancer vaccine development and we divided them into three types. Finally, we give some insights into clinical translation and clinical trial progress of exosome-based anticancer vaccines for future direction.

On-Site Stimulation of Dendritic Cells by Cancer-Derived Extracellular Vesicles on a Core-Shell Nanowire Platform

Extracellular vesicles (EVs) contain a subset of proteins, lipids, and nucleic acids that maintain the characteristics of the parent cell. Immunotherapy using EVs has become a focus of research due to their unique features and bioinspired applications in cancer treatment. Unlike conventional immunotherapy using tumor fragments, EVs can be easily obtained from bodily fluids without invasive actions. We previously fabricated nanowire devices that were specialized for EV collection, but they were not suitable for cell culturing. In this study, we fabricated a ZnO/Al2O3 core-shell nanowire platform that could collect more than 60% of the EVs from the cell supernatant. Additionally, we could continue to culture dendritic cells (DCs) on the platform as an artificial lymph node to investigate cell maturation into antigen-presenting cells. Finally, using this platform, we reproduced a series of on-site immune processes that are among the pivotal immune functions of DCs and include such processes as antigen uptake, antigen presentation, and endocytosis of cancer-derived EVs. This platform provides a new ex vivo tool for EV-DC-mediated immunotherapies.

Umbilical Cord Blood-Derived M1 Macrophage Exosomes Loaded with Cisplatin Target Ovarian Cancer In Vivo and Reverse Cisplatin Resistance

We investigated the therapeutic efficacy of umbilical cord blood (UCB)-derived M1 macrophage exosomes loaded with cisplatin (CIS) in ovarian cancer and platinum resistance. M1 macrophages were purified by using CD14 magnetic beads and characterized by flow cytometry. Our analyses included morphology, particle size, particle concentration, potential, drug loading capacity, counts of entry into cells, antitumor effect in vivo, and the ability to reverse drug resistance. A2780, SKOV3, and A2780/DDP, SKOV3/DDP ovarian cancer cells (CIS-sensitive and CIS-resistant cell lines, respectively) were treated with CIS or CIS-loaded M1 macrophage exosomes (M1exoCISs). The encapsulation efficiency of CIS loading into M1 macrophage exosomes was approximately 30%. In vitro, M1exoCIS treatment reduced the CIS IC50 values of both A2780, SKOV3, and A2780/DDP, SKOV3/DDP cells. We evaluated the effect of M1exoCIS on tumor growth using a mouse ovarian cancer subcutaneous transplantation tumor model inoculated with A2780/DDP cells. M1exoCIS was observed in the liver, spleen, and tumor sites 24 h posttreatment; the fluorescence intensity of M1exoCIS is higher than that of CIS. After 7 days, M1exoCIS significantly inhibited the growth of subcutaneously transplanted tumors compared with CIS alone and had a longer survival time. Moreover, the toxicity test shows that M1exoCIS has less hepatorenal toxicity than CIS. To investigate the mechanism of M1exoCIS targeting, homing, and reversing drug resistance, we performed RT-PCR, Western blotting, and Proteome Profiler Human Receptor Array analyses. We found that A2780 and A2780/DDP cells expressed the integrin β1/CD29 receptor, while M1 exosomes expressed integrin β1/CD29. In addition, M1exos carries long noncoding RNA H19, implicated in PTEN protein upregulation and miR-130a and Pgp gene downregulation, leading to the reversal of CIS drug resistance. Therefore, UCB-derived M1exoCIS target tumor sites of ovarian cancer in vivo and can be used to increase the CIS sensitivity and cytotoxicity.

Cancer treatment therapies: traditional to modern approaches to combat cancers

As far as health issues are concerned, cancer causes one out of every six deaths around the globe. As potent therapeutics are still awaited for the successful treatment of cancer, some unconventional treatments like radiotherapy, surgery, and chemotherapy and some advanced technologies like gene therapy, stem cell therapy, natural antioxidants, targeted therapy, photodynamic therapy, nanoparticles, and precision medicine are available to diagnose and treat cancer. In the present scenario, the prime focus is on developing efficient nanomedicines to treat cancer. Although stem cell therapy has the capability to target primary as well as metastatic cancer foci, it also has the ability to repair and regenerate injured tissues. However, nanoparticles are designed to have such novel therapeutic capabilities. Targeted therapy is also now available to arrest the growth and development of cancer cells without damaging healthy tissues. Another alternative approach in this direction is photodynamic therapy (PDT), which has more potential to treat cancer as it does minimal damage and does not limit other technologies, as in the case of chemotherapy and radiotherapy. The best possible way to treat cancer is by developing novel therapeutics through translational research. In the present scenario, an important event in modern oncology therapy is the shift from an organ-centric paradigm guiding therapy to complete molecular investigations. The lacunae in anticancer therapy may be addressed through the creation of contemporary and pertinent cancer therapeutic techniques. In the meantime, the growth of nanotechnology, material sciences, and biomedical sciences has revealed a wide range of contemporary therapies with intelligent features, adaptable functions, and modification potential. The development of numerous therapeutic techniques for the treatment of cancer is summarized in this article. Additionally, it can serve as a resource for oncology and immunology researchers.

Evaluation of Antioxidant Activity and Drug Delivery Potential of Cell-Derived Extracellular Vesicles from Citrus reticulata Blanco cv. 'Dahongpao'

Plant extracellular vesicles (PEVs) have attracted increasing attention due to their rich composition, good antioxidant and anti-inflammatory activity, and ability to transport drugs. As a common fruit, citrus is an ideal material for extracting PEVs because of the diversity and abundance of bioactive substances in it. In our study, citrus-derived extracellular vesicles (CEVs) were extracted from red mandarin (Citrus reticulata Blanco cv. 'Dahongpao') and it was found that they contain high levels of lipids, proteins, and carbohydrates. The high levels of total phenols and total flavonoids suggest that CEVs have good chemical antioxidant properties. We also demonstrated through cell experiments that CEVs have significant antioxidant and anti-inflammatory effects. Furthermore, we found that CEVs have an encapsulation rate of 71.5 ± 0.19% and a high drug-carrying capacity of 4.96 ± 0.22% and can enhance antioxidant and anti-inflammatory activity when loaded with tangeretin. Our results show that CEVs contain abundant bioactive components, have low toxicity, exhibit good antioxidant and anti-inflammatory properties, and can serve as drug delivery agents. This study has important implications for utilizing citrus materials and developing natural anti-oxidative and anti-inflammatory biomaterials.

An iPSC-derived exosome-pulsed dendritic cell vaccine boosts antitumor immunity in melanoma

Induced pluripotent stem cells (iPSCs) express a broad spectrum of tumor-associated antigens and exert prophylactic effects on various tumors. However, some problems remain, such as potential tumorigenicity, challenges in transport to the lymph nodes and spleen, and limited antitumor effects. Thus, designing a safe and effective iPSC-based tumor vaccine is necessary. We prepared iPSC-derived exosomes and incubated them with DCs (dendritic cells) for pulsing to explore their antitumor effects in murine melanoma models. The antitumor immune response induced by the DC vaccine pulsed with iPSC exosomes (DC + EXO) was assessed in vitro and in vivo. After DC + EXO vaccination, extracted spleen T cells effectively killed a variety of tumor cells (melanoma, lung cancer, breast cancer, and colorectal cancer) in vitro. In addition, DC + EXO vaccination significantly inhibited melanoma growth and lung metastasis in mouse models. Furthermore, DC + EXO vaccination induced long-term T cell responses and prevented melanoma rechallenge. Finally, biocompatibility studies showed that the DC vaccine did not significantly alter the viability of normal cells and mouse viscera. Hence, our research may provide a prospective strategy of a safe and effective iPSC-based tumor vaccine for clinical use.

Extracellular vesicles as next generation immunotherapeutics

Extracellular vesicles (EVs) function as a mode of intercellular communication and molecular transfer to elicit diverse biological/functional response. Accumulating evidence has highlighted that EVs from immune, tumour, stromal cells and even bacteria and parasites mediate the communication of various immune cell types to dynamically regulate host immune response. EVs have an innate capacity to evade recognition, transport and transfer functional components to target cells, with subsequent removal by the immune system, where the immunological activities of EVs impact immunoregulation including modulation of antigen presentation and cross-dressing, immune activation, immune suppression, and immune surveillance, impacting the tumour immune microenvironment. In this review, we outline the recent progress of EVs in immunorecognition and therapeutic intervention in cancer, including vaccine and targeted drug delivery and summarise their utility towards clinical translation. We highlight the strategies where EVs (natural and engineered) are being employed as a therapeutic approach for immunogenicity, tumoricidal function, and vaccine development, termed immuno-EVs. With seminal studies providing significant progress in the sequential development of engineered EVs as therapeutic anti-tumour platforms, we now require direct assessment to tune and improve the efficacy of resulting immune responses - essential in their translation into the clinic. We believe such a review could strengthen our understanding of the progress in EV immunobiology and facilitate advances in engineering EVs for the development of novel EV-based immunotherapeutics as a platform for cancer treatment.

The Genes-Stemness-Secretome Interplay in Malignant Pleural Mesothelioma: Molecular Dynamics and Clinical Hints

MPM has a uniquely poor somatic mutational landscape, mainly driven by environmental selective pressure. This feature has dramatically limited the development of effective treatment. However, genomic events are known to be associated with MPM progression, and specific genetic signatures emerge from the exceptional crosstalk between neoplastic cells and matrix components, among which one main area of focus is hypoxia. Here we discuss the novel therapeutic strategies focused on the exploitation of MPM genetic asset and its interconnection with the surrounding hypoxic microenvironment as well as transcript products and microvesicles representing both an insight into the pathogenesis and promising actionable targets.

Exosomes as smart drug delivery vehicles for cancer immunotherapy

Exosomes (Exos) as drug delivery vehicles have been widely used for cancer immunotherapy owing to their good biocompatibility, low toxicity, and low immunogenicity. Some Exos-based cancer immunotherapy strategies such as tuning of immunosuppressive tumor microenvironment, immune checkpoint blockades, and cancer vaccines have also been investigated in recent years, which all showed excellent therapeutic effects for malignant tumor. Furthermore, some Exos-based drug delivery systems (DDSs) for cancer immunotherapy have also undergone clinic trails, indicating that Exos are a promising drug delivery carrier. In this review, in order to promote the development of Exos-based DDSs in cancer immunotherapy, the biogenesis and composition of Exos, and Exos as drug delivery vehicles for cancer immunotherapy are summarized. Meanwhile, their clinical translation and challenges are also discussed. We hope this review will provide a good guidance for Exos as drug delivery vehicles for cancer immunotherapy.

Potential Roles of Exosomes in the Development and Detection of Malignant Mesothelioma: An Update

Malignant mesothelioma (MM) is a devastating cancer of mesothelial cells, caused by asbestos exposure. Limited knowledge regarding the detection of asbestos exposure and the early diagnosis of MM, as well as a lack of successful treatment options for this deadly cancer, project an immediate need to understand the mechanism(s) of MM development. With the recent discovery of nano-vesicles, namely exosomes, and their enormous potential to contain signature molecules representative of different diseases, as well as to communicate with distant targets, we were encouraged to explore their role(s) in MM biology. In this review, we summarize what we know so far about exosomes and MM based on our own studies and on published literature from other groups in the field. We expect that the information contained in this review will help advance the field of MM forward by revealing the mechanisms of MM development and survival. Based on this knowledge, future therapeutic strategies for MM can potentially be developed. We also hope that the outcome of our studies presented here may help in the detection of MM.

Exploring MicroRNA and Exosome Involvement in Malignant Pleural Mesothelioma Drug Response

Malignant pleural mesothelioma (MPM) is a deadly thoracic malignancy and existing treatment options are limited. Chemotherapy remains the most widely used first-line treatment regimen for patients with unresectable MPM, but is hampered by drug resistance issues. The current study demonstrated a modest enhancement of MPM cell sensitivity to chemotherapy drug treatment following microRNA (miRNA) transfection in MPM cell lines, albeit not for all tested miRNAs. This effect was more pronounced for FAK (PND-1186) small molecule inhibitor treatment; consistent with previously published data. We previously established that MPM response to survivin (YM155) small molecule inhibitor treatment is unrelated to basal survivin expression. Here, we showed that MPM response to YM155 treatment is enhanced following miRNA transfection of YM155-resistant MPM cells. We determined that YM155-resistant MPM cells secrete a higher level of exosomes in comparison to YM155-sensitive MPM cells. Despite this, an exosome inhibitor (GW4896) did not enhance MPM cell sensitivity to YM155. Additionally, our study showed no evidence of a correlation between the mRNA expression of inhibitor of apoptosis (IAP) gene family members and MPM cell sensitivity to YM155. However, two drug transporter genes, ABCA6 and ABCA10, were upregulated in the MPM cell lines and correlated with poor sensitivity to YM155.

Harnessing the Therapeutic Potential of Exosomes: A Novel Strategy for Anticancer and Antiviral Therapy

Exosomes are extracellular membrane bound vesicles released from almost all cell types and can be retrieved from all body fluids. The molecular constituents of these extracellular bodies vary depending on their cell of origin, from which they can transport molecules such as DNA, RNA, proteins lipids, and several metabolites. They have been shown to execute several functions such as in cell growth, migration, differentiation, neuronal signaling, immune cell modulation, and some diseases such as cancer through intercellular communication and signaling. They are also described to act as key players in viral persistence and dissemination. Due to their ability to elicit potent cellular responses, high level of tolerance in host cells, and high efficiency in penetrating other cells, they are proposed to be potential therapeutics as well as vehicles for drug delivery. In recent years, several studies have been conducted in quest for the development of an effective anticancer therapy or antiviral therapy against highly persistent viruses. However, most of these studies become halted due to failure to achieve desired therapeutic outcomes. Nevertheless, the in vitro/in vivo application of exosomes in tumor and infectious disease diagnosis and therapy is prospective. This review discusses the role of exosomes as predictive markers for immune activation and potential targets for anticancer/antiviral therapies.

Engineered extracellular vesicles and their mimetics for cancer immunotherapy

Extracellular vesicles (EVs) are heterogeneous membranous vesicles secreted by living cells that are involved in many physiological and pathological processes as intermediaries for intercellular communication and molecular transfer. Recent studies have shown that EVs can regulate the occurrence and development of tumors by transferring proteins, lipids and nucleic acids to immune cells as signaling molecules. As a new diagnostic biomarker and drug delivery system, EVs have broad application prospects in immunotherapy. In addition, the breakthrough of nanotechnology has promoted the development and exploration of engineered EVs for immune-targeted therapy. Herein, we review the uniqueness of EVs in immune regulation and the engineering strategies used for immunotherapy and highlight the logic of their design through typical examples. The present situation and challenges of clinical transformation are discussed, and the development prospects of EVs in immunotherapy are proposed. The goal of this review is to provide new insights into the design of immune-regulatory EVs and expand their application in cancer immunotherapy.

The tumor-targeted CD40 agonist CEA-CD40 promotes T cell priming via a dual mode of action by increasing antigen delivery to dendritic cells and enhancing their activation

Tumor-targeted CD40 agonism represents an attractive strategy for cancer immunotherapy (CIT) as it promotes dendritic cell (DC) activation and concomitant tumor-specific T cell priming without causing systemic side effects. We developed the bispecific CD40 agonistic antibody CEA-CD40, which triggers CD40 stimulation exclusively in the presence of carcinoembryonic antigen (CEA), a glycoprotein specifically expressed on tumor cells. In this study, we demonstrate that CEA-CD40 can enable potent in vitro DC activation and consecutive T cell cross-priming in a CEA-specific manner. Furthermore, we provide evidence that CEA-CD40 increases colocalization of CEA⁺ tumor material and DCs. Using CEA⁺ tumor-derived extracellular vesicles (EVs), which are known to be an excellent tumor antigen source, we show that CEA-CD40 mediates delivery of CEA⁺ EVs to DCs. Importantly, our data indicates that this fosters acquisition of tumor EV major histocompatibility complex I/peptide complexes by DCs, consequently improving CD8⁺ T cell priming against EV-associated antigen in vitro. Thus, we provide mechanistic evidence for a dual mode of action of CEA-CD40 for CIT: we suggest that CEA-CD40 has the potential to activate DCs and in addition can promote their loading with tumor antigen derived from EVs to trigger tumor-specific T cell cross-priming.

Exosomes: Small vesicles with big roles in cancer, vaccine development, and therapeutics

Cancer is a deadly disease that is globally and consistently one of the leading causes of mortality every year. Despite the availability of chemotherapy, radiotherapy, immunotherapy, and surgery, a cure for cancer has not been attained. Recently, exosomes have gained significant attention due to the therapeutic potential of their various components including proteins, lipids, nucleic acids, miRNAs, and lncRNAs. Exosomes constitute a set of tiny extracellular vesicles with an approximate diameter of 30-100 nm. They are released from different cells and are present in biofluids including blood, cerebrospinal fluid (CSF), and urine. They perform crucial multifaceted functions in the malignant progression of cancer via autocrine, paracrine, and endocrine communications. The ability of exosomes to carry different cargoes including drug and molecular information to recipient cells make them a novel tool for cancer therapeutics. In this review, we discuss the major components of exosomes and their role in cancer progression. We also review important literature about the potential role of exosomes as vaccines and delivery carriers in the context of cancer therapeutics.

Application of immunotherapy based on dendritic cells stimulated by tumor cell-derived exosomes in a syngeneic breast tumor mouse model

We here evaluated the therapeutic effect of tumor cell-derived exosomes (TEXs)-stimulated dendritic cells (DCs) in a syngeneic orthotopic breast tumor model. The DC line DC2.4 and breast cancer cell line E0771 originally isolated from C57BL/6 mice were used. E0771 cells stably expressing the exosomal CD63-RFP or luciferase (Luc) and DC2.4 cells stably expressing GFP were produced using lentivirus. TEXs were purified from conditioned medium of E0771/CD63-RFP cells. Breast tumor model was established by injecting E0771/Luc cells into mammary gland fat pad of mice. TEXs contained immune modulatory molecules such as HSP70, HSP90, MHC I, MHC II, TGF-β, and PD-L1. TEXs were easily taken by DC2.4 cells, resulting in a significant increase in the in vitro proliferation and migration abilities of DC2.4 cells, accompanied by the upregulation of CD40. TEX-DC-treated group exhibited a decreased tumor growth compared with control group. CD8⁺ cells were more abundant in the tumors and lymph nodes of TEX-DC-treated group than in those of control group, whereas many CD4⁺ or FOXP3+ cells were localized in those of control group. Our results suggest a potential application of TEX-DC-based cancer immunotherapy.

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TEXs contained immune modulatory molecules such as HSP70, HSP90, MHC I, MHC II, TGF-β, and PD-L1. .

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TEXs increased the proliferation and migration capacities of dendritic cells.

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TEXs up regulated CD40 molecule on dendritic cells.

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TEX-stimulated dendritic cells suppressed tumor growth, with accompanying increase in CD8⁺ T cell infiltration.

Bioengineering of Extracellular Vesicles: Exosome-Based Next-Generation Therapeutic Strategy in Cancer

Extracellular nano vesicles and exosomes hold compelling evidence in intercellular communication. Exosomal intracellular signal transduction is mediated by the transfer of cargo proteins, lipids, micro (mi)RNAs, long noncoding (lnc)RNAs, small interfering (si)RNAs, DNA, and other functional molecules that play a pivotal role in regulating tumor growth and metastasis. However, emerging research trends indicate that exosomes may be used as a promising tool in anticancer treatment. This review features a majority of the bioengineering applications of fabricated exosomal cargoes. It also encompasses how the manipulation and delivery of specific cargoes-noncoding RNAs (ncRNAs), recombinant proteins, immune-modulators, chemotherapeutic drugs, and other small molecules-may serve as a precise therapeutic approach in cancer management.

Development of Extracellular Vesicle Therapeutics: Challenges, Considerations, and Opportunities

Extracellular vesicles (EVs) hold great promise as therapeutic modalities due to their endogenous characteristics, however, further bioengineering refinement is required to address clinical and commercial limitations. Clinical applications of EV-based therapeutics are being trialed in immunomodulation, tissue regeneration and recovery, and as delivery vectors for combination therapies. Native/biological EVs possess diverse endogenous properties that offer stability and facilitate crossing of biological barriers for delivery of molecular cargo to cells, acting as a form of intercellular communication to regulate function and phenotype. Moreover, EVs are important components of paracrine signaling in stem/progenitor cell-based therapies, are employed as standalone therapies, and can be used as a drug delivery system. Despite remarkable utility of native/biological EVs, they can be improved using bio/engineering approaches to further therapeutic potential. EVs can be engineered to harbor specific pharmaceutical content, enhance their stability, and modify surface epitopes for improved tropism and targeting to cells and tissues in vivo. Limitations currently challenging the full realization of their therapeutic utility include scalability and standardization of generation, molecular characterization for design and regulation, therapeutic potency assessment, and targeted delivery. The fields' utilization of advanced technologies (imaging, quantitative analyses, multi-omics, labeling/live-cell reporters), and utility of biocompatible natural sources for producing EVs (plants, bacteria, milk) will play an important role in overcoming these limitations. Advancements in EV engineering methodologies and design will facilitate the development of EV-based therapeutics, revolutionizing the current pharmaceutical landscape.

Overview of the Therapeutic Applications of Stem Cell-Derived Exosomes: A Research and Commercial Perspective

Progress in extracellular vesicle (EV) research over the past two decades has generated significant interest in using EVs in the biomedical field. Exosomes are a subgroup of EVs that comprise endocytic membrane-bound nanovesicles of 40 to 160 nm diameter. These vesicles have been shown to facilitate intercellular communication via the delivery of cellular molecules. There are currently several exciting applications for exosomes being developed in therapeutics, diagnostics, drug delivery, and cellular reprogramming. Stem cell-derived exosomes present the opportunity to harness the power of stem cells while circumventing several of the risks associated with their use. This review summarizes the recent developments in exosome technology and lends a prospective view to the future of exosome use and application in research and medicine. Through a review of relevant patent filings, recent literature, and ongoing clinical trials, a valuable overview of the field of exosomes is provided. © 2021 Wiley Periodicals LLC.

The Immune Microenvironment of Malignant Pleural Mesothelioma: A Literature Review

Malignant pleural mesothelioma (MPM) is a rare and aggressive tumour with a poor prognosis, associated with asbestos exposure. Nowadays, treatment is based on chemotherapy with a median overall survival of less than two years. This review highlights the main characteristics of the immune microenvironment in MPM with special emphasis on recent biological advances. The MPM microenvironment is highly infiltrated by tumour-associated macrophages, mainly M2-macrophages. In line with infiltration by M2-macrophages, which contribute to immune suppression, other effectors of innate immune response are deficient in MPM, such as dendritic cells or natural killer cells. On the other hand, tumour infiltrating lymphocytes (TILs) are also found in MPM, but CD4+ and CD8+ TILs might have decreased cytotoxic effects through T-regulators and high expression of immune checkpoints. Taken together, the immune microenvironment is particularly heterogeneous and can be considered as mainly immunotolerant or immunosuppressive. Therefore, identifying molecular vulnerabilities is particularly relevant to the improvement of patient outcomes and the assessment of promising treatment approaches.

Murine Leukemia-Derived Extracellular Vesicles Elicit Antitumor Immune Response

Background

Extracellular vesicles (EVs) are heterogeneous lipid bilayer particles secreted by cells. EVs contain proteins, RNA, DNA and other cargo that can have immunomodulatory effects. Cancer-derived EVs have been described as having immunomodulating effects in vivo with immunosuppressive and pro-tumor growth capabilities. However, cancer-derived EVs have also been harnessed and utilized for anti-cancer potential.

Methods

To assess the immunomodulatory effect of EVs produced by acute myeloid leukemia (AML) cells, we isolated vesicles secreted by the murine AML cell line, C1498, and investigated their effect on in vitro and in vivo immune responses.

Results

These leukemia-derived EVs were found to induce increased proliferation of CD3+ cells and enhanced cytolytic activity of CD3+ cells directed toward leukemic cells in vitro. Injection of leukemia-derived EVs into syngeneic naïve mice induced T cell responses in vivo and resulted in enhanced immune responses upon T cell re-stimulation in vitro.

Conclusion

These findings indicate that C1498-derived EVs have immunomodulatory effects on cell-mediated immune responses that could potentially be utilized to facilitate anti-leukemia immune responses.

Extracellular vesicles in immunomodulation and tumor progression

Extracellular vesicles have emerged as prominent regulators of the immune response during tumor progression. EVs contain a diverse repertoire of molecular cargo that plays a critical role in immunomodulation. Here, we identify the role of EVs as mediators of communication between cancer and immune cells. This expanded role of EVs may shed light on the mechanisms behind tumor progression and provide translational diagnostic and prognostic tools for immunologists.

Myeloid-derived suppressor cells: Bridging the gap between inflammation and pancreatic adenocarcinoma

Pancreatic cancer has been identified as one of the deadliest malignancies because it remains asymptomatic and usually presents in the advanced stage. Tumour immune evasion is a well-known mechanism of tumorigenesis in various forms of human malignancies. Chronic inflammation via complex networking of various inflammatory cytokines in the local tissue microenvironment dysregulates the immune system and support tumour development. Pro-inflammatory mediators present in the tumour microenvironment increase the tumour burden by causing immune suppression through the generation of myeloid-derived suppressor cells (MDSCs) and T regulatory cells. These cells, along-with myofibroblasts, create a highly immunosuppressive and resistant tumour microenvironment and are thus considered as one of the culprits for the failure of anti-cancer chemotherapies in pancreatic adenocarcinoma patients. Targeting these MDSCs using various combinatorial approaches might have the potential for abrogating the resistance and suppressive nature of the pancreatic tumour microenvironment. Therefore, there is more curiosity in studying the crosstalk of MDSCs with other immune cells during pathological conditions and the underlying mechanisms of immunosuppression in the current scenario. In this article, the possible role of MDSCs in inflammation-mediated tumour progression of pancreatic adenocarcinoma has been discussed.

Tumor-Derived Exosomes Enriched by miRNA-124 Promote Anti-tumor Immune Response in CT-26 Tumor-Bearing Mice

Exosomes have been introduced as a new alternative delivery system for the transmission of small molecules. Tumor-derived exosomes (TEXs) not only contain tumor-associated antigens to stimulate antitumor immune responses but also act as natural carriers of microRNAs. The aim of the current study was to evaluate the efficacy of miR-124-3p-enriched TEX (TEXomiR) as cell-free vaccine in the induction of antitumor immune responses in a mouse model of colorectal cancer. Briefly, the exosomes were isolated from cultured CT-26 cell line, and modified calcium chloride method was used to deliver miR-124-3p mimic into the exosomes. We used a CT-26-induced BALB/c mouse model of colorectal cancer and analyzed the effect of TEXomiR on survival, tumor size, spleen and tumor-infiltrated lymphocytes, and splenocyte proliferation. Furthermore, intra-tumor regulatory T cells, cytotoxic activity of the splenocytes, and cytokine secretion was also evaluated to describe the anti-tumor immune response. When the tumor size reached 100 mm³, the mice were injected with TEXomiR, TEX, and/or phosphate-buffered saline (PBS) subcutaneously three times with 3-day interval, and then tumor size was monitored every 2 days. The in vitro results indicated that TEXs could efficiently deliver functional miR-124-3p mimic. The in vivo evaluation in tumor-bearing mice showed that treatment with TEXomiR can elicit a stronger anti-tumor immune response than unloaded TEX and PBS. Significant tumor growth inhibition and increased median survival time was achieved in tumor-bearing mice treated with TEXomiR. A significant decrease in CD4/CD8 and Treg/CD8 ratio in tumor tissue was demonstrated. Moreover, increased cytotoxicity and proliferation of splenocytes in the TEXomiR group compared to the TEX and PBS groups were identified. Taken together, our data demonstrated that tumor-derived exosomes efficiently deliver miR-124-3p mimic, and TEXomiR promotes anti-tumor immune responses.

Factors Affecting Extracellular Vesicles Based Drug Delivery Systems

Extracellular vesicles (EVs) play major roles in intracellular communication and participate in several biological functions in both normal and pathological conditions. Surface modification of EVs via various ligands, such as proteins, peptides, or aptamers, offers great potential as a means to achieve targeted delivery of therapeutic cargo, i.e., in drug delivery systems (DDS). This review summarizes recent studies pertaining to the development of EV-based DDS and its advantages compared to conventional nano drug delivery systems (NDDS). First, we compare liposomes and exosomes in terms of their distinct benefits in DDS. Second, we analyze what to consider for achieving better isolation, yield, and characterization of EVs for DDS. Third, we summarize different methods for the modification of surface of EVs, followed by discussion about different origins of EVs and their role in developing DDS. Next, several major methods for encapsulating therapeutic cargos in EVs have been summarized. Finally, we discuss key challenges and pose important open questions which warrant further investigation to develop more effective EV-based DDS.

Dendritic cells loaded with exosomes derived from cancer stem cell-enriched spheroids as a potential immunotherapeutic option

Cancer stem cells (CSCs) are responsible for therapeutic resistance and recurrence in colorectal cancer. Despite advances in immunotherapy, the inability to specifically eradicate CSCs has led to treatment failure. Hence, identification of appropriate antigen sources is a major challenge in designing dendritic cell (DC)‐based therapeutic strategies against CSCs. Here, in an in vitro model using the HT‐29 colon cancer cell line, we explored the efficacy of DCs loaded with exosomes derived from CSC‐enriched colonospheres (CSC_enr‐EXOs) as an antigen source in activating CSC‐specific T‐cell responses. HT‐29 lysate, HT‐29‐EXOs and CSC_enr lysate were independently assessed as separate antigen sources. Having confirmed CSCs enrichment in spheroids, CSC_enr‐EXOs were purified and characterized, and their impact on DC maturation was investigated. Finally, the impact of the antigen‐pulsed DCs on the proliferation rate and also spheroid destructive capacity of autologous T cells was assessed. CSC_enr‐EXOs similar to other antigen groups had no suppressive/negative impacts on phenotypic maturation of DCs as judged by the expression level of costimulatory molecules. Notably, similar to CSC_enr lysate, CSC_enr‐EXOs significantly increased the IL‐12/IL‐10 ratio in supernatants of mature DCs. CSC_enr‐EXO‐loaded DCs effectively promoted T‐cell proliferation. Importantly, T cells stimulated with CSC_enr‐EXOs disrupted spheroids' structure. Thus, CSC_enr‐EXOs present a novel and promising antigen source that in combination with conventional tumour bulk‐derived antigens should be further explored in pre‐clinical immunotherapeutic settings for the efficacy in hampering recurrence and metastatic spread.

Regulation of Antitumor Immune Responses by Exosomes Derived from Tumor and Immune Cells

Exosomes are lipid membrane-enclosed vesicles released by all cell types that act at the paracrine or endocrine level to favor cell differentiation, tissue homeostasis, organ remodeling and immune regulation. Their biosynthesis begins with a cell membrane invagination which generates an early endosome that matures to a late endosome. By inward budding of the late endosome membrane, a multivesicular body (MVB) with intraluminal vesicles (ILVs) is generated. The fusion of MVBs with the plasma membrane releases ILVs into the extracellular space as exosomes, ranging in size from 30 to 100 nm in diameter. The bilipid exosome membrane is rich in cholesterol, ceramides and phosphatidylserine and can be loaded with DNA, RNA, microRNAs, proteins and lipids. It has been demonstrated that exosome secretion is a common mechanism used by the tumor to generate an immunosuppressive microenvironment that favors cancer development and progression, allowing tumor escape from immune control. Due to their ability to transport proteins, lipids and nucleic acids from the cell that gave rise to them, exosomes can be used as a source of biomarkers with great potential for clinical applications in diagnostic, prognostic or therapeutic areas. This article will review the latest research findings on exosomes and their contribution to cancer development.

Extracellular Vesicles: An Emerging Nanoplatform for Cancer Therapy

Extracellular vesicles (EVs) are cell-derived membrane particles that represent an endogenous mechanism for cell-to-cell communication. Since discovering that EVs have multiple advantages over currently available delivery platforms, such as their ability to overcome natural barriers, intrinsic cell targeting properties, and circulation stability, the potential use of EVs as therapeutic nanoplatforms for cancer studies has attracted considerable interest. To fully elucidate EVs' therapeutic function for treating cancer, all current knowledge about cellular uptake and trafficking of EVs will be initially reviewed. In order to further improve EVs as anticancer therapeutics, engineering strategies for cancer therapy have been widely explored in the last decade, along with other cancer therapies. However, therapeutic applications of EVs as drug delivery systems have been limited because of immunological concerns, lack of methods to scale EV production, and efficient drug loading. We will review and discuss recent progress and remaining challenges in developing EVs as a delivery nanoplatform for cancer therapy.

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.

A Protocol for Isolation, Purification, Characterization, and Functional Dissection of Exosomes

Extracellular vesicles (EVs) are membrane-enclosed vesicles released by cells. They carry proteins, nucleic acids, and metabolites which can be transferred to a recipient cell, locally or at a distance, to elicit a functional response. Since their discovery over 30 years ago, the functional repertoire of EVs in both physiological (e.g., organ morphogenesis, embryo implantation) and pathological (e.g., cancer, neurodegeneration) conditions has cemented their crucial role in intercellular communication. Moreover, because the cargo encapsulated within circulating EVs remains protected from degradation, their diagnostic as well as therapeutic (such as drug delivery tool) applications have garnered vested interest. Global efforts have been made to purify EV subtypes from biological fluids and in vitro cell culture media using a variety of strategies and techniques, with a major focus on EVs of endocytic origin called exosomes (30-150 nm in size). Given that the secretome comprises of soluble secreted proteins, protein aggregates, RNA granules, and EV subtypes (such as exosomes, shed microvesicles, apoptotic bodies), it is imperative to purify exosomes to homogeneity if we are to perform biochemical and biophysical characterization and, importantly, functional dissection. Besides understanding the composition of EV subtypes, defining molecular bias of how they reprogram target cells also remains of paramount importance in this area of active research. Here, we outline a systematic "how to" protocol (along with useful insights/tips) to obtain highly purified exosomes and perform their biophysical and biochemical characterization. This protocol employs a mass spectrometry-based proteomics approach to characterize the protein composition of exosomes. We also provide insights on different isolation strategies and their usefulness in various downstream applications. We outline protocols for lipophilic labeling of exosomes to study uptake by a recipient cell, investigating cellular reprogramming using proteomics and studying functional response to exosomes in the Transwell-Matrigel™ Invasion assay.

Defined serum-free three-dimensional culture of umbilical cord-derived mesenchymal stem cells yields exosomes that promote fibroblast proliferation and migration in vitro

Stem cell-derived exosomes are emerging as novel and clinically relevant cell-free therapeutics for regenerative therapy. This work focused on investigating the stimulation of fibroblasts by exosomes derived from umbilical cord-derived mesenchymal stem cells (ucMSC) in a defined serum-free three-dimensional (3D) culture. 3D culture of ucMSC was carried out in medium supplemented with KnockOut serum replacement (KO-medium) using the Aggrewell system. ucMSC in KO-medium formed spheroids with maintained size and integrity throughout culture. This enabled the isolation of vesicles from ucMSC spheroids in KO-medium with sizes that fall within the exosomal size range and were positive for the expression of canonical exosomal markers CD63, CD9, CD81, Alix, and TSG101. The ucMSC-derived exosomes (ExoucMSC ) were shown to significantly increase the migration and proliferation of murine fibroblasts in vitro. To conclude, 3D culture of ucMSC in defined serum-free KO-medium formed viable spheroids which enabled the isolation of ExoucMSC with the potential of accelerating wound healing.

Exosomes: Cell-Derived Nanoplatforms for the Delivery of Cancer Therapeutics

Exosomes are cell-secreted nanovesicles that naturally contain biomolecular cargoes such as lipids, proteins, and nucleic acids. Exosomes mediate intercellular communication, enabling the transfer biological signals from the donor cells to the recipient cells. Recently, exosomes are emerging as promising drug delivery vehicles due to their strong stability in blood circulation, high biocompatibility, low immunogenicity, and natural targeting ability. In particular, exosomes derived from specific types of cells can carry endogenous signaling molecules with therapeutic potential for cancer treatment, thus presenting a significant impact on targeted drug delivery and therapy. Furthermore, exosomes can be engineered to display targeting moieties on their surface or to load additional therapeutic agents. Therefore, a comprehensive understanding of exosome biogenesis and the development of efficient exosome engineering techniques will provide new avenues to establish convincing clinical therapeutic strategies based on exosomes. This review focuses on the therapeutic applications of exosomes derived from various cells and the exosome engineering technologies that enable the accurate delivery of various types of cargoes to target cells for cancer therapy.

Emerging Role of Extracellular Vesicles in Immune Regulation and Cancer Progression

Simple Summary

Accumulating evidence has reported that extracellular vesicles secreted by different tumor microenvironment cells can interfere with the host immune system. These vesicles transmit the signals in the tumor microenvironment that affect the proliferation, apoptosis, activation, and, metabolism of immune cells such as dendritic cells, T cells, macrophages, and natural killer cells, creating a pro-tumoral environment for tumor progression and survival. In this review, we summarize the recent literature on the function of extracellular vesicles derived from tumor cells and immune cells in regulating the critical processes associated with cancer progression. Besides, we also provide insights on how the extracellular vesicles are employed as diagnostic and prognostic biomarkers and drug carriers in cancer.

Abstract

The development of effective therapies for cancer treatment requires a better understanding of the tumor extracellular environment and a dynamic interaction between tumor cells, the cells of the immune system, and the tumor stroma. Increasing evidence suggests that extracellular vesicles play an important role in this interaction. Extracellular vesicles are nanometer-sized membrane-bound vesicles secreted by various types of cells that facilitate intracellular communication by transferring proteins, various lipids, and nucleic acids, especially miRNAs, between cells. Extracellular vesicles play discrete roles in the immune regulatory functions, such as antigen presentation, and activation or suppression of immune cells. Achieving therapeutic intervention through targeting of extracellular vesicles is a crucial area of research now. Thus, a deeper knowledge of exosome biology and the molecular mechanism of immune regulation is likely to provide significant insight into therapeutic intervention utilizing extracellular vesicles to combat this dreadful disease. This review describes the recent updates on immune regulation by extracellular vesicles in cancer progression and possible use in cancer therapy.

Exosome-based immunotherapy: a promising approach for cancer treatment

In the era of the rapid development of cancer immunotherapy, there is a high level of interest in the application of cell-released small vesicles that stimulate the immune system. As cell-derived nanovesicles, exosomes show great promise in cancer immunotherapy because of their immunogenicity and molecular transfer function. The cargoes carried on exosomes have been recently identified with improved technological advances and play functional roles in the regulation of immune responses. In particular, exosomes derived from tumor cells and immune cells exhibit unique composition profiles that are directly involved in anticancer immunotherapy. More importantly, exosomes can deliver their cargoes to targeted cells and thus influence the phenotype and immune-regulation functions of targeted cells. Accumulating evidence over the last decade has further revealed that exosomes can participate in multiple cellular processes contributing to cancer development and therapeutic effects, showing the dual characteristics of promoting and suppressing cancer. The potential of exosomes in the field of cancer immunotherapy is huge, and exosomes may become the most effective cancer vaccines, as well as targeted antigen/drug carriers. Understanding how exosomes can be utilized in immune therapy is important for controlling cancer progression; additionally, exosomes have implications for diagnostics and the development of novel therapeutic strategies. This review discusses the role of exosomes in immunotherapy as carriers to stimulate an anti-cancer immune response and as predictive markers for immune activation; furthermore, it summarizes the mechanism and clinical application prospects of exosome-based immunotherapy in human cancer.

Functionalized exosome harboring bioactive molecules for cancer therapy

Exosomes are nanosized vesicles with a lipid membrane that are secreted by most cells and play a crucial role as intermediates of intercellular communication because they carry bioactive molecules. Exosomes are promising for drug delivery of chemicals, proteins, and nucleic acids owing to their inherent properties such as excellent biocompatibility, high tumor targetability, and prolonged circulation in vivo. In this review, we cover recent approaches and advances made in the field of exosome-mediated delivery of bioactive molecules for cancer therapy and factors that affect the clinical use of exosomes. This review can be used as a guideline for further study in expanding the utility of therapeutic exosomes.

Three-dimensional culture of dental pulp pluripotent-like stem cells (DPPSCs) enhances Nanog expression and provides a serum-free condition for exosome isolation

Stem cell-derived exosomes have been identified as novel cell-free therapeutics for regenerative medicine. Three-dimensional (3D) culture of stem cells were reported to improve their "stemness" and therapeutic efficacy. This work focused on establishing serum-free 3D culture of dental pulp pluripotent-like stem cells (DPPSCs)-a newly characterized pluripotent-like stem cell for exosome production. DPPSCs were expanded in regular 2D culture in human serum-supplemented (HS)-medium and transferred to a micropatterned culture plate for 3D culture in HS-medium (default) and medium supplemented with KnockOut™ serum replacement (KO-medium). Bright-field microscopy observation throughout the culture period (24 days) revealed that DPPSCs in KO-medium formed spheroids of similar morphology and size to that in HS-medium. qRT-PCR analysis showed similar Oct4A gene expression in DPPSC spheroids in both HS-medium and KO-medium, but Nanog expression significantly increased in the latter. Vesicles isolated from DPPSC spheroids in KO-medium in the first 12 days of culture showed sizes that fall within the exosomal size range by nanoparticle tracking analysis (NTA) and express the canonical exosomal markers. It is concluded that 3D culture of DPPSCs in KO-medium provided an optimal serum-free condition for successful isolation of DPPSC-derived exosomes for subsequent applications in regenerative medicine.

Perspectives in Manipulating EVs for Therapeutic Applications: Focus on Cancer Treatment

Extracellular vesicles (EVs) receive special attention from oncologists due to their assumed usefulness as prognostic markers, vaccines to induce anti-cancer immune response, and physiological delivery tools. The latter application, which supports the reduction of side effects of treatment, is still fraught with many challenges, including established methods for loading EVs with selected cargo and directing them towards target cells. EVs could be loaded with selected cargo either in vitro using several physicochemical techniques, or in vivo by modification of parental cell, which may have an advantage over in vitro procedures, since some of them significantly influence EVs’ properties. Otherwise, our research findings suggest that EVs could be passively supplemented with micro RNAs (miRNAs) or miRNA antagonists to induce expected biological effect. Furthermore, our observations imply that antigen-specific antibody light chains could coat the surface of EVs to increase the specificity of cell targeting. Finally, the route of EVs’ administration also determines their bioavailability and eventually induced therapeutic effect. Besides, EV membrane lipids may possibly possess immune adjuvant activity. The review summarizes the current knowledge on the possibilities to manipulate EVs to use them as a delivery tool, with the special emphasis on anti-cancer therapy.

Methods for the Determination of the Purity of Exosomes

BACKGROUND

Exosomes open exciting new opportunities for advanced drug transport and targeted release. Furthermore, exosomes may be used for vaccination, immunosuppression or wound healing. To fully utilize their potential as drug carriers or immune-modulatory agents, the optimal purity of exosome preparations is of crucial importance.

METHODS

Articles describing the isolation and purification of exosomes were retrieved from the PubMed database.

RESULTS

Exosomes are often separated from biological fluids containing high concentrations of proteins, lipids and other molecules that keep vesicle purification challenging. A great number of purification protocols have been published, however, their outcome is difficult to compare because the assessment of purity has not been standardized. In this review, we first give an overview of the generation and composition of exosomes, as well as their multifaceted biological functions that stimulated various medical applications. Finally, we describe various methods that have been used to purify small vesicles and to assess the purity of exosome preparations and critically compare the quality of these evaluation protocols.

CONCLUSION

Combinations of various techniques have to be applied to reach the required purity and quality control of exosome preparations.

Tumor-derived exosomes: the next generation of promising cell-free vaccines in cancer immunotherapy

Identification of immunogenic tumor antigens that are efficiently processed and delivered by dendritic cells to prime the immune system and to induce an appropriate immune response is a research hotspot in the field of cancer vaccine development. High biosafety is an additional demand. Tumor-derived exosomes (TEXs) are nanosized lipid bilayer encapsulated vesicles that shuttle bioactive information to the tumor microenvironment facilitating tumor progression. However, accumulating evidence points toward the capacity of TEXs to efficiently stimulate immune responses against tumors provided they are appropriately administered. After briefly describing the function of exosomes in cancer biology and their communication with immune cells, we summarize in this review in vitro and preclinical studies eliciting the potency of TEXs in inducing effective anti-tumor responses and recently modified strategies further improving TEX-vaccination efficacy. We interpret the available data as TEXs becoming a lead in cancer vaccination based on tumor antigen-selective high immunogenicity.

Application of mesenchymal stem cell exosomes and their drug-loading systems in acute liver failure

Stem cell exosomes are nanoscale membrane vesicles released from stem cells of various origins that can regulate signal transduction pathways between liver cells, and their functions in intercellular communication have been recognized. Due to their natural substance transport properties and excellent biocompatibility, exosomes can also be used as drug carriers to release a variety of substances, which has great prospects in the treatment of critical and incurable diseases. Different types of stem cell exosomes have been used to study liver diseases. Due to current difficulties in the treatment of acute liver failure (ALF), this review will outline the potential of stem cell exosomes for ALF treatment. Specifically, we reviewed the pathogenesis of acute liver failure and the latest progress in the use of stem cell exosomes in the treatment of ALF, including the role of exosomes in inhibiting the ALF inflammatory response and regulating signal transduction pathways, the advantages of stem cell exosomes and their use as a drug‐loading system, and their pre‐clinical application in the treatment of ALF. Finally, the clinical research status of stem cell therapy for ALF and the current challenges of exosome clinical transformation are summarized.

Noninvasive Photoacoustic Imaging of Dendritic Cell Stimulated with Tumor Cell-Derived Exosome

PURPOSE

The tools to trigger dendritic cell (DC) activation and to verify DC migration in vivo are important for directing DC immunotherapy toward successful treatment. We evaluated whether tumor cell-derived exosome (TEX)-stimulated DC migration into lymph node (LN) in mouse could be tracked using gold nanoparticle (GN)-labeling and ultrasound (US)-guided photoacoustic imaging (PAI).

PROCEDURES

GFP-transduced DC2.4 cells were used. RFP-tagged TEXs were purified from a stable 4T1 cell line overexpressing the exosomal CD63-RFP fusion protein. The TEX uptake by DCs was visualized using confocal laser scanning microscopy. GNs with surface plasmon resonance at 808 nm were used for DC-labeling. DCs that migrated into axillary LN were longitudinally monitored by US-guided PAI and analyzed by silver staining and immunohistochemistry.

RESULTS

TEXs were easily internalized in DCs, increased proliferation and migration capacities, and upregulated co-stimulatory molecules, CCR7 and TNF-α without cytotoxicity. The GN-labeling exerted no adverse effects on the biological functions of DCs. US-guided PAI and DC-labeling allowed for sensitive and longitudinal monitoring of TEX-stimulated DC migration toaxillary LN.

CONCLUSIONS

TEXs efficiently activated DCs and GN-labeled DC migration into LN was successfully monitored using US-guided PAI, suggesting that TEXs are a good source for DC activation and US-guided PAI is a cost-effective and easy-to-use imaging modality for noninvasive tracking of DCs.

Alarmin-painted exosomes elicit persistent antitumor immunity in large established tumors in mice

Treating large established tumors is challenging for dendritic cell (DC)-based immunotherapy. DC activation with tumor cell-derived exosomes (TEXs) carrying multiple tumor-associated antigen can enhance tumor recognition. Adding a potent adjuvant, high mobility group nucleosome-binding protein 1 (HMGN1), boosts DCs’ ability to activate T cells and improves vaccine efficiency. Here, we demonstrate that TEXs painted with the functional domain of HMGN1 (TEX-N1ND) via an exosomal anchor peptide potentiates DC immunogenicity. TEX-N1ND pulsed DCs (DC_TEX-N1ND) elicit long-lasting antitumor immunity and tumor suppression in different syngeneic mouse models with large tumor burdens, most notably large, poorly immunogenic orthotopic hepatocellular carcinoma (HCC). DC_TEX-N1ND show increased homing to lymphoid tissues and contribute to augmented memory T cells. Importantly, N1ND-painted serum exosomes from cancer patients also promote DC activation. Our study demonstrates the potency of TEX-N1ND to strengthen DC immunogenicity and to suppress large established tumors, and thus provides an avenue to improve DC-based immunotherapy.

The use of tumour exosome-activated dendritic cell (DC) immunotherapy shows promise for the treatment of large established tumours. Here, the authors generate alarmin HMGN1-attached tumour exosomes which significantly improve therapy efficacy by boosting DC activation in several preclinical mouse models.

Extracellular vesicles as biomarkers in malignant pleural mesothelioma: A review

Extracellular vesicles (EV) are secreted by all cells, including cancer cells, as a mode of intercellular transport and communication. The main types of EV known to date include exosomes, microvesicles and apoptotic bodies, as well as oncosomes and large oncosomes, which are specific to cancer cells. These different EV populations carry specific cargo from one cell to another to stimulate a specific response. They can be found in all body fluids and can be detected in liquid biopsies. EV released from mesothelioma cells can reveal important information about the molecules and signalling pathways involved in the development and progression of the tumour. The presence of tumour-derived EV in circulating body fluids makes them potential novel biomarkers for early diagnosis, prognostication and surveillance of cancer. In this review, we explore the characteristics and functional roles of EV reported in the literature, with a focus on their role in malignant pleural mesothelioma.

Transcytosis of Bacillus subtilis extracellular vesicles through an in vitro intestinal epithelial cell model

Bacterial EVs have been related to inter-kingdom communication between probiotic/pathogenic bacteria and their hosts. Our aim was to investigate the transcytosis process of B. subtilis EVs using an in vitro intestinal epithelial cell model. In this study, using Confocal Laser Scanning Microscopy, we report that uptake and internalization of CFSE-labeled B. subtilis EVs (115 nm ± 27 nm) by Caco-2 cells are time-dependent. To study the transcytosis process we used a transwell system and EVs were quantified in the lower chamber by Fluorescence and Nanoparticle Tracking Analysis measurements. Intact EVs are transported across a polarized cell monolayer at 60-120 min and increased after 240 min with an estimated average uptake efficiency of 30% and this process is dose-dependent. EVs movement into intestinal epithelial cells was mainly through Z axis and scarcely on X and Y axis. This work demonstrates that EVs could be transported across the gastrointestinal epithelium. We speculate this mechanism could be the first step allowing EVs to reach the bloodstream for further delivery up to extraintestinal tissues and organs. The expression and further encapsulation of bioactive molecules into natural nanoparticles produced by probiotic bacteria could have practical implications in food, nutraceuticals and clinical therapies.

Exosomes and cancer: From oncogenic roles to therapeutic applications

Exosomes belong to extracellular vehicles that were produced and secreted from most eukaryotic cells and are involved in cell-to-cell communications. They are an effective delivery system for biological compounds such as mRNAs, microRNAs (miRNAs), proteins, lipids, saccharides, and other physiological compounds to target cells. In this way, they could influence on cellular pathways and mediate their physiological behaviors including cell proliferation, tumorigenesis, differentiation, and so on. Many research studies focused on their role in cancers and also on potentially therapeutic and biomarker applications. In the current study, we reviewed the exosomes' effects on cancer progression based on their cargoes including miRNAs, long noncoding RNAs, circular RNAs, DNAs, mRNAs, proteins, and lipids. Moreover, their therapeutic roles in cancer were considered. In this regard, we have given a brief overview of challenges and obstacles in using exosomes as therapeutic agents.

Immunotherapy Based on Dendritic Cell-Targeted/-Derived Extracellular Vesicles-A Novel Strategy for Enhancement of the Anti-tumor Immune Response

Dendritic cell (DC)-based anti-tumor vaccines have great potential for the treatment of cancer. To date, a large number of clinical trials involving DC-based vaccines have been conducted with a view to treating tumors of different histological origins. However, DC-based vaccines had several drawbacks, including problems with targeted delivery of tumor antigens to DCs and prolong storage of cellular vaccines. Therefore, the development of other immunotherapeutic approaches capable of enhancing the immunogenicity of existing DC-based vaccines or directly triggering anti-tumor immune responses is of great interest. Extracellular vesicles (EVs) are released by almost all types of eukaryotic cells for paracrine signaling. EVs can interact with target cells and change their functional activity by delivering different signaling molecules including mRNA, non-coding RNA, proteins, and lipids. EVs have potential benefits as natural vectors for the delivery of RNA and other therapeutic molecules targeted to DCs, T-lymphocytes, and tumor cells; therefore, EVs are a promising entity for the development of novel cell-free anti-tumor vaccines that may be a favourable alternative to DC-based vaccines. In the present review, we discuss the anti-tumor potential of EVs derived from DCs, tumors, and other cells. Methods of EV isolation are systematized, and key molecules carried by EVs that are necessary for the activation of a DC-mediated anti-tumor immune response are analyzed with a focus on the RNA component of EVs. Characteristics of anti-tumor immune responses induced by EVs in vitro and in vivo are reviewed. Finally, perspectives and challenges with the use of EVs for the development of anti-tumor cell-free vaccines are considered.

Intercellular Crosstalk Via Extracellular Vesicles in Tumor Milieu as Emerging Therapies for Cancer Progression

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Increasing evidence has suggested that extracellular vesicles (EV) mediated bidirectional transfer of functional molecules (such as proteins, different types of RNA, and lipids) between cancer cells and tumor stromal cells (immune cells, endothelial cells, fibroblasts, stem cells) and strongly contributed to the reinforcement of cancer progression. Thus, intercellular EV-mediated signaling in tumor microenvironment (TME) is essential in the modulation of all processes that support and promote tumor development like immune suppression, angiogenesis, invasion and metastasis, and resistance of tumor cells to anticancer treatments.

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Besides EV potential to revolutionize our understanding of the cancer cell-stromal cells crosstalk in TME, their ability to selectively transfer different cargos to recipient cells has created excitement in the field of tumortargeted delivery of specific molecules for anticancer treatments. Therefore, in tight connection with previous findings, this review brought insight into the dual role of EV in modulation of TME. Thus, on one side EV create a favorable phenotype of tumor stromal cells for tumor progression; however, as a future new class of anticancer drug delivery systems EV could re-educate the TME to overcome main supportive processes for malignancy progression.