Engineering Exosomes Endowed with Targeted Delivery of Triptolide for Malignant Melanoma Therapy

Recent progress in engineered extracellular vesicles and their biomedical applications

AIMS

To present the recent update on the isolation, engineering techniques for extracellular vesicles, limitations associated with different isolation techniques, different biomedical applications, and challenges of engineered extracellular vesicles for the benefit of researchers from academic, industry, etc. MATERIALS AND METHODS: Peer-reviewed articles from most recognized journals were collected, and presented information was analyzed to discuss collection, chemical, electroporation, cellular, and membrane surface engineering to design extracellular vesicles for various therapeutic applications. In addition, we present the applications and limitations of techniques for the collection of extracellular vesicles.

KEY FINDINGS

There is a need for isolation techniques with the gold standard. However, advanced extracellular vesicle isolation techniques showed improved recovery, and purity of extracellular vesicles. Tumor therapy is a major part of the therapy section that illustrates the role of engineered extracellular vesicles in synergetic therapy such as phototherapy, theragnostic, and delivery of genetic materials. In addition, extracellular vesicles have shown their potential in the treatment of retinal disorders, neurodegenerative disease, tuberculosis, osteoporosis, inflammatory bowel disease, vaccine production, and wound healing.

SIGNIFICANCE

Engineered extracellular vesicles can deliver cargo to the specific cells, elicit an immune response and could be used for the development of the vaccines in the future. However, the progress is at the initial stage. Overall, this review will provide a comprehensive understanding and could serve as a reference for researchers in the clinical translation of engineered extracellular vesicles in different biomedical fields.

Engineered hsa-miR-455-3p-Abundant Extracellular Vesicles Derived from 3D-Cultured Adipose Mesenchymal Stem Cells for Tissue-Engineering Hyaline Cartilage Regeneration

Efforts are made to enhance the inherent potential of extracellular vesicles (EVs) by utilizing 3D culture platforms and engineered strategies for functional cargo-loading. Three distinct types of adipose mesenchymal stem cells-derived EVs (ADSCs-EVs) are successfully isolated utilizing 3D culture platforms consisting of porous gelatin methacryloyl (PG), PG combined with sericin methacryloyl (PG/SerMA), or PG combined with chondroitin sulfate methacryloyl (PG/ChSMA). These correspond to PG-EVs, PG/SerMA-EVs, and PG/ChSMA-EVs, respectively. Unique microRNA (miRNA) profiles are observed in each type of ADSCs-EVs. Notably, PG-EVs encapsulate higher levels of hsa-miR-455-3p and deliver more hsa-miR-455-3p to chondrocytes, which results in the activation of the hsa-miR-455-3p/PAK2/Smad2/3 axis and the subsequent hyaline cartilage regeneration. Furthermore, the functionality of PG-EVs is optimized through engineered strategies, including agomir/lentivirus transfection, electroporation, and Exo-Fect transfection. These strategies, referred to as Agomir-EVs, Lentivirus-EVs, Electroporation-EVs, and Exo-Fect-EVs, respectively, are ranked based on their efficacy in encapsulating hsa-miR-455-3p, delivering hsa-miR-455-3p to chondrocytes, and promoting cartilage formation via the hsa-miR-455-3p/PAK2/Smad2/3 axis. Notably, Exo-Fect-EVs exhibit the highest efficiency. Collectively, the 3D culture conditions and engineered strategies have an impact on the miRNA profiles and cartilage regeneration capabilities of ADSCs-EVs. The findings provide valuable insights into the mechanisms underlying the promotion of cartilage regeneration by ADSCs-EVs.

Exosomes-based dual drug-loaded nanocarrier for targeted and multiple proliferative vitreoretinopathy therapy

Proliferative vitreoretinopathy (PVR) is a common cause of vision loss after retinal reattachment surgery and ocular trauma. The key pathogenic mechanisms of PVR development include the proliferation, migration and epithelial-mesenchymal transition (EMT) of retinal pigment epithelial cells (RPEs) activated by the growth factors and cytokines after surgery. Although some drugs have been tried in PVR treatments as basic investigations, the limited efficacy remains an obstacle, which may be due to the single pharmacological action and lack of targeting. Herein, the anti-proliferative Daunorubicin and anti-inflammatory Dexamethasone were co-loaded in the RPEs-derived exosomes (Exos), obtaining an Exos-based dual drug-loaded nanocarrier (Exos@D-D), and used for multiple PVR therapy. Owing to the advantages of homologous Exos and the dual drug loading, Exos@D-D showed good RPEs targeting as well as improved uptake efficiency, and could inhibit the proliferation, migration, as well as EMT of RPEs effectively. The animal studies have also demonstrated that Exos@D-D effectively inhibits the production of proliferative membranes and prevents the further development of inflammation, shows significant therapeutic effects on PVR and good biocompatibility. Such Exos-based dual drug-loaded nanocarrier investigation not only provides a promising approach for multifunctional exosome drug delivery systems construction, but also has great potential in PVR clinical therapy application.

Nintedanib-loaded exosomes from adipose-derived stem cells inhibit pulmonary fibrosis induced by bleomycin

BACKGROUND

Pulmonary fibrosis (PF) is a progressive lung disorder with a high mortality rate; its therapy remains limited due to the inefficiency of drug delivery. In this study, the system of drug delivery of nintedanib (Nin) by exosomes derived from adipose-derived stem cells (ADSCs-Exo, Exo) was developed to effectively deliver Nin to lung lesion tissue to ensure enhanced anti-fibrosis therapy.

METHODS

The bleomycin (BLM)-induced PF model was constructed in vivo and in vitro. The effects of Exo-Nin on BLM-induced PF and its regulatory mechanism were examined using RT-qPCR, Western blotting, immunofluorescence, and H&E staining.

RESULTS

We found Exo-Nin significantly improved BLM-induced PF in vivo and in vitro compared to Nin and Exo groups alone. Mechanistically, Exo-Nin alleviated fibrogenesis by suppressing endothelial-mesenchymal transition through the down-regulation of the TGF-β/Smad pathway and the attenuation of oxidative stress in vivo and in vitro.

CONCLUSIONS

Utilizing adipose stem cell-derived exosomes as carriers for Nin exhibited a notable enhancement in therapeutic efficacy. This improvement can be attributed to the regenerative properties of exosomes, indicating promising prospects for adipose-derived exosomes in cell-free therapies for PF.

IMPACT

The system of drug delivery of nintedanib (Nin) by exosomes derived from adipose-derived stem cells was developed to effectively deliver Nin to lung lesion tissue to ensure enhanced anti-fibrosis therapy. The use of adipose stem cell-derived exosomes as the carrier of Nin may increase the therapeutic effect of Nin, which can be due to the regenerative properties of the exosomes and indicate promising prospects for adipose-derived exosomes in cell-free therapies for PF.

Collision of herbal medicine and nanotechnology: a bibliometric analysis of herbal nanoparticles from 2004 to 2023

BACKGROUND

Herbal nanoparticles are made from natural herbs/medicinal plants, their extracts, or a combination with other nanoparticle carriers. Compared to traditional herbs, herbal nanoparticles lead to improved bioavailability, enhanced stability, and reduced toxicity. Previous research indicates that herbal medicine nanomaterials are rapidly advancing and making significant progress; however, bibliometric analysis and knowledge mapping for herbal nanoparticles are currently lacking. We performed a bibliometric analysis by retrieving publications related to herbal nanoparticles from the Web of Science Core Collection (WoSCC) database spanning from 2004 to 2023. Data processing was performed using the R package Bibliometrix, VOSviewers, and CiteSpace.

RESULTS

In total, 1876 articles related to herbal nanoparticles were identified, originating from various countries, with China being the primary contributing country. The number of publications in this field increases annually. Beijing University of Chinese Medicine, Shanghai University of Traditional Chinese Medicine, and Saveetha University in India are prominent research institutions in this domain. The Journal "International Journal of Nanomedicine" has the highest number of publications. The number of authors of these publications reached 8234, with Yan Zhao, Yue Zhang, and Huihua Qu being the most prolific authors and Yan Zhao being the most frequently cited author. "Traditional Chinese medicine," "drug delivery," and "green synthesis" are the main research focal points. Themes such as "green synthesis," "curcumin," "wound healing," "drug delivery," and "carbon dots" may represent emerging research areas.

CONCLUSIONS

Our study findings assist in identifying the latest research frontiers and hot topics, providing valuable references for scholars investigating the role of nanotechnology in herbal medicine.

Significance of TRAIL/Apo-2 ligand and its death receptors in apoptosis and necroptosis signalling: Implications for cancer-targeted therapeutics

The human immune defensesystem routinely expresses the tumour necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL), which is the most prevalent element for antitumor immunity. TRAIL associates with its death receptors (DRs), DR4 (TRAIL-R1), and DR5 (TRAIL-R2), in cancer cells to initiate the intracellular apoptosis cascade. Accordingly, numerous academic institutions and pharmaceutical companies havetried to exploreTRAIL's capacity to kill tumourcells by producing recombinant versions of it (rhTRAIL) or TRAIL receptor agonists (TRAs) [monoclonal antibody (mAb), synthetic and natural compounds, etc.] and molecules that sensitize TRAIL signalling pathway for therapeutic applications. Recently, several microRNAs (miRs) have been found to activate or inhibit death receptor signalling. Therefore, pharmacological regulation of these miRs may activate or resensitize the TRAIL DRs signal, and this is a novel approach for developing anticancer therapeutics. In this article, we will discuss TRAIL and its receptors and molecular pathways by which it induces various cell death events. We will unravel potential innovative applications of TRAIL-based therapeutics, and other investigated therapeutics targeting TRAIL-DRs and summarize the current preclinical pharmacological studies and clinical trials. Moreover, we will also emphasizea few situations where future efforts may be addressed to modulate the TRAIL signalling pathway.

Orally Deliverable Sequence-Targeted Fucoxanthin-Loaded Biomimetic Extracellular Vesicles for Alleviation of Nonalcoholic Fatty Liver Disease

Extracellular vesicles (EVs) possess favorable biocompatibility and immunological characteristics, making them optimal carriers for bioactive substances. In this study, an innovative hepatic-targeted vesicle system encapsulating with fucoxanthin (GA-LpEVs-FX) was successfully designed and used to alleviate nonalcoholic fatty liver disease. The formulation entails the self-assembly of EVs derived from Lactobacillus paracasei (LpEVs), modification with glycyrrhetinic acid (GA) via amide reaction offering the system liver-targeting capacity and loading fucoxanthin (FX) through sonication treatment. In vitro experiments demonstrated that GA-LpEVs-FX effectively mitigated hepatic lipid accumulation and attenuated reactive oxygen species-induced damage resulting lipid accumulation (p < 0.05). In vivo, GA-LpEVs-FX exhibited significant downregulation of lipogenesis-related proteins, namely, fatty acid synthase (FAS), acetyl-CoA carboxylase (ACC1), and sterol regulatory element binding protein 1 (SREBP-1), subsequently ameliorating lipid metabolism disorders (p < 0.05), and the stability of GA-LpEVs-FX significantly improved compared to free FX. These findings establish a novel formulation for utilizing foodborne components for nonalcoholic fatty liver disease alleviation.

Extracellular vesicles as tools and targets in therapy for diseases

Extracellular vesicles (EVs) are nano-sized, membranous structures secreted into the extracellular space. They exhibit diverse sizes, contents, and surface markers and are ubiquitously released from cells under normal and pathological conditions. Human serum is a rich source of these EVs, though their isolation from serum proteins and non-EV lipid particles poses challenges. These vesicles transport various cellular components such as proteins, mRNAs, miRNAs, DNA, and lipids across distances, influencing numerous physiological and pathological events, including those within the tumor microenvironment (TME). Their pivotal roles in cellular communication make EVs promising candidates for therapeutic agents, drug delivery systems, and disease biomarkers. Especially in cancer diagnostics, EV detection can pave the way for early identification and offers potential as diagnostic biomarkers. Moreover, various EV subtypes are emerging as targeted drug delivery tools, highlighting their potential clinical significance. The need for non-invasive biomarkers to monitor biological processes for diagnostic and therapeutic purposes remains unfulfilled. Tapping into the unique composition of EVs could unlock advanced diagnostic and therapeutic avenues in the future. In this review, we discuss in detail the roles of EVs across various conditions, including cancers (encompassing head and neck, lung, gastric, breast, and hepatocellular carcinoma), neurodegenerative disorders, diabetes, viral infections, autoimmune and renal diseases, emphasizing the potential advancements in molecular diagnostics and drug delivery.

Exosome-based delivery strategies for tumor therapy: an update on modification, loading, and clinical application

Malignancy is a major public health problem and among the leading lethal diseases worldwide. Although the current tumor treatment methods have therapeutic effect to a certain extent, they still have some shortcomings such as poor water solubility, short half-life, local and systemic toxicity. Therefore, how to deliver therapeutic agent so as to realize safe and effective anti-tumor therapy become a problem urgently to be solved in this field. As a medium of information exchange and material transport between cells, exosomes are considered to be a promising drug delivery carrier due to their nano-size, good biocompatibility, natural targeting, and easy modification. In this review, we summarize recent advances in the isolation, identification, drug loading, and modification of exosomes as drug carriers for tumor therapy alongside their application in tumor therapy. Basic knowledge of exosomes, such as their biogenesis, sources, and characterization methods, is also introduced herein. In addition, challenges related to the use of exosomes as drug delivery vehicles are discussed, along with future trends. This review provides a scientific basis for the application of exosome delivery systems in oncological therapy.

Emerging role of extracellular vesicles in veterinary practice: novel opportunities and potential challenges

Extracellular vesicles are nanoscale vesicles that transport signals between cells, mediating both physiological and pathological processes. EVs facilitate conserved intercellular communication. By transferring bioactive molecules between cells, EVs coordinate systemic responses, regulating homeostasis, immunity, and disease progression. Given their biological importance and involvement in pathogenesis, EVs show promise as biomarkers for veterinary diagnosis, and candidates for vaccine production, and treatment agents. Additionally, different treatment or engineering methods could be used to boost the capability of extracellular vesicles. Despite the emerging veterinary interest, EV research has been predominantly human-based. Critical knowledge gaps remain regarding isolation protocols, cargo loading mechanisms, in vivo biodistribution, and species-specific functions. Standardized methods for veterinary EV characterization and validation are lacking. Regulatory uncertainties impede veterinary clinical translation. Advances in fundamental EV biology and technology are needed to propel the veterinary field forward. This review introduces EVs from a veterinary perspective by introducing the latest studies, highlighting their potential while analyzing challenges to motivate expanded veterinary investigation and translation.

Encapsulation and assessment of therapeutic cargo in engineered exosomes: a systematic review

Exosomes are nanoscale extracellular vesicles secreted by cells and enclosed by a lipid bilayer membrane containing various biologically active cargoes such as proteins, lipids, and nucleic acids. Engineered exosomes generated through genetic modification of parent cells show promise as drug delivery vehicles, and they have been demonstrated to have great therapeutic potential for treating cancer, cardiovascular, neurological, and immune diseases, but systematic knowledge is lacking regarding optimization of drug loading and assessment of delivery efficacy. This review summarizes current approaches for engineering exosomes and evaluating their drug delivery effects, and current techniques for assessing exosome drug loading and release kinetics, cell targeting, biodistribution, pharmacokinetics, and therapeutic outcomes are critically examined. Additionally, this review synthesizes the latest applications of exosome engineering and drug delivery in clinical translation. The knowledge compiled in this review provides a framework for the rational design and rigorous assessment of exosomes as therapeutics. Continued advancement of robust characterization methods and reporting standards will accelerate the development of exosome engineering technologies and pave the way for clinical studies.

Exosomes as Targeted Delivery Drug System: Advances in Exosome Loading, Surface Functionalization and Potential for Clinical Application

Exosomes are subtypes of vesicles secreted by almost all cells and can play an important role in intercellular communication. They contain various proteins, lipids, nucleic acids and other natural substances from their metrocytes. Exosomes are expected to be a new generation of drug delivery systems due to their low immunogenicity, high potential to transfer bioactive substances and biocompatibility. However, exosomes themselves are not highly targeted, it is necessary to develop new surface modification techniques and targeted drug delivery strategies, which are the focus of drug delivery research. In this review, we introduced the biogenesis of exosomes and their role in intercellular communication. We listed various advanced exosome drug-loading techniques. Emphatically, we summarized different exosome surface modification techniques and targeted drug delivery strategies. In addition, we discussed the application of exosomes in vaccines and briefly introduced milk exosomes. Finally, we clarified the clinical application prospects and shortcomings of exosomes.

Biology and function of exosomes in tumor immunotherapy

Exosomes are nano-scale extracellular vesicles that are found widely in various biological fluids. As messengers, exosomes deliver characteristic biological information from donor cells, facilitating their accumulation and subsequent transfer of information to tumor immune cells. Immunotherapy is a cutting-edge strategy for cancer therapy, but it has not yet reached its full potential owing to severe side effects and limited efficacy. Exosomes possess antigens and immunostimulatory molecules and can serve as cell-free vaccines to induce antitumor immunity. In addition, given their stability, low immunogenicity, and targeting ability, exosomes represent ideal drug delivery systems in tumor immunotherapy by delivering cargoes, including non-coding ribonucleic acids (RNAs), membrane proteins, chemotherapeutic agents, and immune cell death inducers. Exosomes can also be engineered to precisely target tumor cells. However, as a rising star in tumor immunotherapy, exosomes are also impeded by some challenges, including the lack of uniform technical standards for their isolation and purification, the need to improve exosomal cargo loading for efficient exosome delivery, and the expansion of clinical trials, which are currently in their infancy. Long-term, multi-center, and large-scale clinical trials are needed to evaluate the performance of exosomes in the future. Nonetheless, exosomes have demonstrated encouraging performance in tumor immunotherapy. In this review, we summarize the potential and challenges of exosomes in tumor immunotherapy, with the aim to shed light on exosomes as new-era tumor immunotherapy tools.

Nanodrug Delivery Strategies to Signaling Pathways in Alopecia

Over 50% of the global population suffers from hair loss. The mixed results in the treatment of hair loss reveal the limitations of conventional commercial topical drugs. One the one hand, the definite pathogenesis of hair loss is still an enigma. On the other hand, targeted drug carriers ensure the drug therapeutic effect and low side effects. This review highlights the organization and overview of nine crucial signaling pathways associated with hair loss, as well as the development of nanobased topical delivery systems loading the clinical drugs, which will fuel emerging hair loss treatment strategies.

Haematopoietic cell-derived exosomes in cancer development and therapeutics: From basic science to clinical practice

BACKGROUND

The tumour microenvironment (TME) is a specialised niche involving intercellular communication among cancer cells and various host cells. Among the host cells, the quantity and quality of immune cells within the TME play essential roles in cancer development and management. The immunologically suppressive, so-called 'cold' TME established by a series of tumour-host interactions, including generating immunosuppressive cytokines and recruiting regulatory host immune cells, is associated with resistance to therapies and worse clinical outcomes.

MAIN BODY

Various therapeutic approaches have been used to target the cold TME, including immune checkpoint blockade therapy and adoptive T-cell transfer. A promising, less explored therapeutic strategy involves targeting TME-associated exosomes. Exosomes are nanometer-sized, extracellular vesicles that transfer material from donor to recipient cells. These particles can reprogram the recipient cells and modulate the TME. In particular, exosomes from haematopoietic cells are known to promote or suppress cancer progression under specific conditions. Understanding the effects of haematopoietic cell-secreted exosomes may foster the development of therapeutic exosomes (tExos) for personalised cancer treatment. However, the development of exosome-based therapies has unique challenges, including scalable production, purification, storage and delivery of exosomes and controlling batch variations. Clinical trials are being conducted to verify the safety, feasibility, availability and efficacy of tExos.

CONCLUSION

This review summarises our understanding of how haematopoietic cell-secreted exosomes regulate the TME and antitumour immunity and highlights present challenges and solutions for haematopoietic cell-derived exosome-based therapies.

Engineered extracellular vesicles-like biomimetic nanoparticles as an emerging platform for targeted cancer therapy

Nanotechnology offers the possibility of revolutionizing cancer theranostics in the new era of precision oncology. Extracellular vesicles (EVs)-like biomimetic nanoparticles (EBPs) have recently emerged as a promising platform for targeted cancer drug delivery. Compared with conventional synthetic vehicles, EBPs have several advantages, such as lower immunogenicity, longer circulation time, and better targeting capability. Studies on EBPs as cancer therapeutics are rapidly progressing from in vitro experiments to in vivo animal models and early-stage clinical trials. Here, we describe engineering strategies to further improve EBPs as effective anticancer drug carriers, including genetic manipulation of original cells, fusion with synthetic nanomaterials, and direct modification of EVs. These engineering approaches can improve the anticancer performance of EBPs, especially in terms of tumor targeting effectiveness, stealth property, drug loading capacity, and integration with other therapeutic modalities. Finally, the current obstacles and future perspectives of engineered EBPs as the next-generation delivery platform for anticancer drugs are discussed.

Tumor-targeted exosomes for delivery of anticancer drugs

Exosomes are small phospholipid bilayer vesicles that are naturally produced by all living cells, both prokaryotes and eukaryotes. The exosomes due to their unique size, reduced immunogenicity, and their ability to mimic synthetic liposomes in carrying various anticancer drugs have been tested as drug delivery vehicles for cancer treatment. An added advantage of developing exosomes as a drug carrier is the ease of manipulating their intraluminal content and their surface modification to achieve tumor-targeted drug delivery. In the past ten-years, there has been an exponential increase in the number of exosome-related studies in cancer. Preclinical studies demonstrate exosomes-mediated delivery of chemotherapeutics, biologicals and natural products produce potent anticancer activity both, in vitro and in vivo. In contrast, the number of exosome-based clinical trials are few due to challenges in the manufacturing and scalability related to large-scale production of exosomes and their storage and stability. Herein, we discuss recent advances in exosome-based drug delivery for cancer treatment in preclinical and clinical studies and conclude with challenges to be overcome for translating a larger number of exosome-based therapies into the clinic.

Research progress of exosomes as drug carriers in cancer and inflammation

Extracellular vesicles (EVs) could be produced by most cells and play an important role in disease development. As a subtype of EVs, exosomes exhibit suitable size, rich surface markers and diverse contents, making them more appealing as potential drug carriers. Compared with traditional synthetic nanoparticles, exosomes possess superior biocompatibility and much lower immunogenicity. This work reviewed the most up-to-date research progress of exosomes as carriers for nucleic acids, proteins and small molecule drugs for cancer and inflammation management. The drug loading strategies and potential cellular uptake behaviour of exosomes are highlighted, trying to provide reference for future exosome design and application.

Targeted delivery of triptolide by dendritic cell-derived exosomes for colitis and rheumatoid arthritis therapy in murine models

BACKGROUND AND PURPOSE

Triptolide (TP) elicits a beneficial effect in the treatment of autoimmune diseases, such as ulcerative colitis (UC) and rheumatoid arthritis (RA). However, its multiorgan toxicity needs to be resolved. Dendritic cells (DCs) are the primary target of TP, which induces immunosuppression, and DC-derived exosomes (DEX) can selectively enter DCs in vivo. Here, we encapsulated TP with DEX (DEXTP) to generate TP-targeted delivery to reduce toxicity.

EXPERIMENTAL APPROACH

The effect of DEXTP was evaluated in murine colitis and RA models. Toxicity was examined by haematoxylin and eosin staining and serum biochemical marker detection. Affinity of DEXs for DCs was tracked by fluorescent labelling. The immune environment was evaluated and mimicked in vitro for further analysis of the mechanism.

KEY RESULTS

DEXTP effectively carried TP to DCs in vivo, and alleviated local inflammation and damage in colitis and RA mice with no obvious toxicity. Additionally, DEXTP reshaped the immune milieu by decreasing CD4⁺ T-cell levels and increasing regulatory T-cell levels in vivo. Furthermore, consistent T-cell differentiation was observed in vitro, and DC activation was inhibited by alterations in surface factors and secrete cytokines, and by induction of apoptosis or other form of death.

CONCLUSIONS AND IMPLICATIONS

Encapsulating TP with DEX is a new method that both reduces the toxicity of TP and induces immunosuppression in UC and RA mice. The underlying immune mechanism involves DEXTP targeting DCs in vivo, to inhibit DC activation and induce DC apoptosis, which further induces T-cell immunosuppression.

Extracellular Vesicles-Based Cell-Cell Communication in Melanoma: New Perspectives in Diagnostics and Therapy

Extracellular vesicles (EVs) are a heterogeneous group of cell-secreted particles that carry cargo of functional biomolecules crucial for cell-to-cell communication with both physiological and pathophysiological consequences. In this review, we focus on evidence demonstrating that the EV-mediated crosstalk between melanoma cells within tumor, between melanoma cells and immune and stromal cells, promotes immune evasion and influences all steps of melanoma development from local progression, pre-metastatic niche formation, to metastatic colonization of distant organs. We also discuss the role of EVs in the development of resistance to immunotherapy and therapy with BRAF^V600/MEK inhibitors, and shortly summarize the recent advances on the potential applications of EVs in melanoma diagnostics and therapy.

Advances in Extracellular Vesicle Nanotechnology for Precision Theranostics

Extracellular vesicles (EVs) have increasingly been recognized as important cell surrogates influencing many pathophysiological processes, including cellular homeostasis, cancer progression, neurologic disease, and infectious disease. These behaviors enable EVs broad application prospects for clinical application in disease diagnosis and treatment. Many studies suggest that EVs are superior to conventional synthetic carriers in terms of drug delivery and circulating biomarkers for early disease diagnosis, opening up new frontiers for modern theranostics. Despite these clinical potential, EVs containing diverse cellular components, such as nucleic acids, proteins, and metabolites are highly heterogeneous and small size. The limitation of preparatory, engineering and analytical technologies for EVs poses technical barriers to clinical translation. This article aims at present a critical overview of emerging technologies in EVs field for biomedical applications and challenges involved in their clinic translations. The current methods for isolation and identification of EVs are discussed. Additionally, engineering strategies developed to enhance scalable production and improved cargo loading as well as tumor targeting are presented. The superior clinical potential of EVs, particularly in terms of different cell origins and their application in the next generation of diagnostic and treatment platforms, are clarified.

Exploiting the potential of extracellular vesicles as delivery vehicles for the treatment of melanoma

Melanoma, the most aggressive skin cancer that originated from genetic mutations in the melanocytes, is still a troublesome medical problem under the current therapeutic approaches, which include surgical resection, chemotherapy, photodynamic therapy, immunotherapy, biochemotherapy and targeted therapy. Nanotechnology has significantly contributed to the development of cancer treatment in the past few years, among which extracellular vesicles (EVs) are nanosized lipid bilayer vesicles secreted from almost all cells that play essential roles in many physiological and pathological processes. In terms of melanoma therapy, the unique physicochemical properties of EVs make them promising nanocarriers for drug transportation compared to other synthetic nanocarriers. Moreover, EVs can be further engineered to maximize their drug delivery potential. Herein, in this minireview, we gave a brief overview of EV-based drug delivery strategies for melanoma therapy, in which different therapeutics delivered via EVs were summarized. We also highlighted the current progress of the EV-based delivery platform for melanoma therapy in clinical trials. The obstacles to applying exosomes in clinical practice toward further translation of EVs melanoma therapy were also discussed at the end. In summary, EVs offer promising prospects for melanoma therapy, whilst the ways for unlocking EVs’ full potential in melanoma therapies should be further investigated by solving relevant issues which hamper EVs-based melanoma therapy translation in the future.

Targeting Capabilities of Native and Bioengineered Extracellular Vesicles for Drug Delivery

Extracellular vesicles (EVs) are highly promising as drug delivery vehicles due to their nanoscale size, stability and biocompatibility. EVs possess natural targeting abilities and are known to traverse long distances to reach their target cells. This long-range organotropism and the ability to penetrate hard-to-reach tissues, including the brain, have sparked interest in using EVs for the targeted delivery of pharmaceuticals. In addition, EVs can be readily harvested from an individual’s biofluids, making them especially suitable for personalized medicine applications. However, the targeting abilities of unmodified EVs have proven to be insufficient for clinical applications. Multiple attempts have been made to bioengineer EVs to fine-tune their on-target binding. Here, we summarize the current state of knowledge on the natural targeting abilities of native EVs. We also critically discuss the strategies to functionalize EV surfaces for superior long-distance targeting of specific tissues and cells. Finally, we review the challenges in achieving specific on-target binding of EV nanocarriers.

Engineering Milk-Derived Exosome for Enhancing Cellular Astaxanthin Delivery

Astaxanthin (AST), a fat-soluble carotenoid, shows excellent antioxidant and anti-inflammatory activities, but its low biocompatibility and stability limit its application in the food industry. In this work, we constructed the targeted hyaluronic acid (HA)-modified milk exosome-based astaxanthin delivery system to improve the biocompatibility stability and targeted transport properties of astaxanthin. Nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FTIR) showed that HA was efficiently modified onto the surface of the milk exosome by an amide condensation reaction. The fluorescence images showed that the targeted delivery system accumulated in RAW264.7 macrophages, and the targeting effect on inflammatory cells was significantly enhanced. Compared with free astaxanthin, the delivery system could enhance the cellular uptake of astaxanthin and alleviate the overproduction of reactive oxygen species significantly and the depolarization of mitochondrial membrane potential in a lipopolysaccharide-induced cellular model. The delivery system also notably inhibited the expression of IL-1β, IL-6, and other inflammatory factors. Therefore, the targeted hyaluronic acid-modified milk exosome-based astaxanthin delivery system prevents the activation of macrophages and the production of inflammatory mediators and has the potential to apply to the prevention of chronic inflammatory diseases.

αvβ3 integrin-specific exosomes engineered with cyclopeptide for targeted delivery of triptolide against malignant melanoma

Background

Melanoma is the most malignant skin tumor and is difficult to cure with the alternative treatments of chemotherapy, biotherapy, and immunotherapy. Our previous study showed that triptolide (TP) exhibited powerful tumoricidal activity against melanoma. However, the clinical potential of TP is plagued by its poor aqueous solubility, short half-life, and biotoxicity. Therefore, developing an ideal vehicle to efficiently load TP and achieving targeted delivery to melanoma is a prospective approach for making full use of its antitumor efficacy.

Results

We applied exosome (Exo) derived from human umbilical cord mesenchymal stromal cells (hUCMSCs) and engineered them exogenously with a cyclic peptide, arginine-glycine-aspartate (cRGD), to encapsulate TP to establish a bionic-targeted drug delivery system (cRGD-Exo/TP), achieving synergism and toxicity reduction. The average size of cRGD-Exo/TP was 157.34 ± 6.21 nm, with a high drug loading of 10.76 ± 1.21%. The in vitro antitumor results showed that the designed Exo delivery platform could be effectively taken up by targeted cells and performed significantly in antiproliferation, anti-invasion, and proapoptotic activities in A375 cells via the caspase cascade and mitochondrial pathways and cell cycle alteration. Furthermore, the biodistribution and pharmacokinetics results demonstrated that cRGD-Exo/TP possessed superior tumor targetability and prolonged the half-life of TP. Notably, cRGD-Exo/TP significantly inhibited tumor growth and extended survival time with negligible systemic toxicity in tumor-bearing mice.

Conclusion

The results indicated that the functionalized Exo platform provides a promising strategy for targeted therapy of malignant melanoma.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-022-01597-1.

Microfluidic Approaches for Affinity-Based Exosome Separation

As a subspecies of extracellular vesicles (EVs), exosomes have provided promising results in diagnostic and theranostic applications in recent years. The nanometer-sized exosomes can be extracted by liquid biopsy from almost all body fluids, making them especially suitable for mainly non-invasive point-of-care (POC) applications. To achieve this, exosomes must first be separated from the respective biofluid. Impurities with similar properties, heterogeneity of exosome characteristics, and time-related biofouling complicate the separation. This practical review presents the state-of-the-art methods available for the separation of exosomes. Furthermore, it is shown how new separation methods can be developed. A particular focus lies on the fabrication and design of microfluidic devices using highly selective affinity separation. Due to their compactness, quick analysis time and portable form factor, these microfluidic devices are particularly suitable to deliver fast and reliable results for POC applications. For these devices, new manufacturing methods (e.g., laminating, replica molding and 3D printing) that use low-cost materials and do not require clean rooms are presented. Additionally, special flow routes and patterns that increase contact surfaces, as well as residence time, and thus improve affinity purification are displayed. Finally, various analyses are shown that can be used to evaluate the separation results of a newly developed device. Overall, this review paper provides a toolbox for developing new microfluidic affinity devices for exosome separation.

Immune-Cell-Derived Exosomes for Cancer Therapy

Exosomes are a type of extracellular vesicles secreted by cells in normal or pathological conditions for cell-cell communication. With immunomodulatory characteristics and potential therapeutic properties, immune-cell-derived exosomes play an important role in cancer therapy. They express various antigens on their surface, which can be employed for antigen presentation, immunological activation, and metabolic regulation, leading to the killing of cancerous cells. In addition, immune-cell-derived exosomes have received extensive attention as a drug delivery platform in effective antitumor therapy due to their excellent biocompatibility, low immunogenicity, and high loading capacity. In this review, the biological and therapeutic characteristics of immune-cell-derived exosomes are comprehensively outlined. The antitumor mechanism of exosomes secreted by immune cells, including macrophages, dendritic cells, T cells, B cells, and natural killer cells, are systematically summarized. Moreover, the applications of immune-cell-derived exosomes as nanocarriers to transport antitumor agents (chemotherapeutic drugs, genes, proteins, etc.) are discussed. More importantly, the existing challenges of immune-cell-derived exosomes are pointed out, and their antitumor potentials are also discussed.

Bioinspired soft nanovesicles for site-selective cancer imaging and targeted therapies

Cell-to-cell communication within the heterogeneous solid tumor environment plays a significant role in the uncontrolled metastasis of cancer. To inhibit the metastasis and growth of cancer cells, various chemically designed and biologically derived nanosized biomaterials have been applied for targeted cancer therapeutics applications. Over the years, bioinspired soft nanovesicles have gained tremendous attention for targeted cancer therapeutics due to their easy binding with tumor microenvironment, natural targeting ability, bio-responsive nature, better biocompatibility, high cargo capacity for multiple therapeutics agents, and long circulation time. These cell-derived nanovesicles guard their loaded cargo molecules from immune clearance and make them site-selective to cancer cells due to their natural binding and delivery abilities. Furthermore, bioinspired soft nanovesicles prevent cell-to-cell communication and secretion of cancer cell markers by delivering the therapeutics agents predominantly. Cell-derived vesicles, namely, exosomes, extracellular vesicles, and so forth have been recognized as versatile carriers for therapeutic biomolecules. However, low product yield, poor reproducibility, and uncontrolled particle size distribution have remained as major challenges of these soft nanovesicles. Furthermore, the surface biomarkers and molecular contents of these vesicles change with respect to the stage of disease and types. Here in this review, we have discussed numerous examples of bioinspired soft vesicles for targeted imaging and cancer therapeutic applications with their advantages and limitations. Importance of bioengineered soft nanovesicles for localized therapies with their clinical relevance has also been addressed in this article. Overall, cell-derived nanovesicles could be considered as clinically relevant platforms for cancer therapeutics. This article is categorized under: Biology-Inspired Nanomaterials > Nucleic Acid-Based Structures Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Extracellular Vesicles as Novel Drug-Delivery Systems through Intracellular Communications

Since it has been reported that extracellular vesicles (EVs) carry cargo using cell-to-cell comminication according to various in vivo situations, they are exprected to be applied as new drug-delivery systems (DDSs). In addition, non-coding RNAs, such as microRNAs (miRNAs), have attracted much attention as potential biomarkers in the encapsulated extracellular-vesicle (EV) form. EVs are bilayer-based lipids with heterogeneous populations of varying sizes and compositions. The EV-mediated transport of contents, which includes proteins, lipids, and nucleic acids, has attracted attention as a DDS through intracellular communication. Many reports have been made on the development of methods for introducing molecules into EVs and efficient methods for introducing them into target vesicles. In this review, we outline the possible molecular mechanisms by which miRNAs in exosomes participate in the post-transcriptional regulation of signaling pathways via cell–cell communication as novel DDSs, especially small EVs.

Exosome-Mediated Therapeutic Strategies for Management of Solid and Hematological Malignancies

Exosomes are small membrane vesicles of endocytic origin containing cytokines, RNAs, growth factors, proteins, lipids, and metabolites. They have been identified as fundamental intercellular communication controllers in several diseases and an enormous volume of data confirmed that exosomes could either sustain or inhibit tumor onset and diffusion in diverse solid and hematological malignancies by paracrine signaling. Thus, exosomes might constitute a promising cell-free tumor treatment alternative. This review focuses on the effects of exosomes in the treatment of tumors, by discussing the most recent and promising data from in vitro and experimental in vivo studies and the few existing clinical trials. Exosomes are extremely promising as transporters of drugs, antagomir, genes, and other therapeutic substances that can be integrated into their core via different procedures. Moreover, exosomes can augment or inhibit non-coding RNAs, change the metabolism of cancer cells, and modify the function of immunologic effectors thus modifying the tumor microenvironment transforming it from pro-tumor to antitumor milieu. Here, we report the development of currently realized exosome modifiers that offer indications for the forthcoming elaboration of other more effective methods capable of enhancing the activity of the exosomes.

Membrane protein-chimeric liposome-mediated delivery of triptolide for targeted hepatocellular carcinoma therapy

Triptolide (TPL) is a diterpenoid triepoxide with broad antitumor efficacy, while lack of mechanism of action, severe systemic toxicity, and poor water solubility of TPL limited its usage. To unveil the mechanism of action and improve the pharmaceutical properties of TPL, here we explored the molecular mechanism of TPL and then fabricated TPL-loaded membrane protein-chimeric liposomes (TPL@MP-LP) and tested its anticancer efficacy against hepatocellular carcinoma (HCC). CCK8 assay, colony formation assay, EdU assay, and flow cytometry were used to examine the activity of TPL. RNA sequence and gain-and-loss of function assays were used to explore the molecular mechanisms. TPL@MP-LP was characterized by size, zeta potential, polydispersity index, and transmission electron microscopy. Cellular uptake and cell viability assay were performed to evaluate the internalization and anticancer efficacy of TPL@MP-LP in vitro. Biodistribution and in vivo antitumor efficacy of TPL@MP-LP were evaluated on orthotopic HCC mice models. TPL robustly inhibited HCC cells by inducing cell proliferation arrest, apoptosis via the mitochondrial pathway, and necroptosis via RIPK1/RIPK3/MLKL signaling. TPL was successfully loaded into MP-LP, with a drug-loading capacity of 5.62 ± 0.80%. MP-LP facilitated TPL internalization and TPL@MP-LP exerted enhanced anticancer efficacy against Huh7 cells. TPL@MP-LP showed targeting ability to the tumor site. More importantly, TPL@MP-LP treatment suppressed tumor growth but showed minimal damage to liver and renal functions. TPL exerted anticancer effects on HCC via inducing cell proliferation arrest, apoptosis, and necroptosis, and the MP-LP might be a promising delivery strategy to improve the antitumor efficacy while mitigating toxicity of TPL for HCC therapy.