Therapeutic applications of extracellular vesicles: clinical promise and open questions

The Construction of Biomimetic Cementum Through a Combination of Bioskiving and Fluorine-Containing Biomineralization

Despite tremendous attention is given to the construction of biomimetic cementum for regeneration of tooth cementum, the lack of recapitulating the composition and hierarchical structure of cementum often leads to the poor performance of constructed materials. How to highly mimic the sophisticated composition and hierarchy of cementum remains a longstanding challenge in constructing the biomimetic cementum. Inspired by cementum formation process, a novel construction approach via a combination of bioskiving and fluorine-containing biomineralization is developed in this study. The alternative collagen lamellae (ACL) that can highly mimic the rotated plywood structure of cementum collagen matrix is fabricated via bioskiving. Followed by biomineralization in the amorphous calcium phosphate (ACP) solution with different concentration of fluorine, a series of biomimetic cementum is constructed. Screened by physicochemical characterization, the biomimetic cementum with the composition and hierarchical structure highly similar to human cementum is selected. Through in vitro biological assay, this biomimetic cementum is proven to significantly promote the adhesion, proliferation, and cementogenic differentiation of periodontal ligament cells (PDLCs). Furthermore, in vivo study demonstrates that biomimetic cementum could induce cementogenesis. This biomimetic cementum constructed via combinatory application of bioskiving and fluorine-containing biomineralization stands as a promising candidate for achieving cementum regeneration.

Human Pluripotent Stem Cell-Derived Extracellular Vesicles: Characteristics and Applications

Extracellular vesicles (EVs), including exosomes and microvesicles, are found to play an important role in various biological processes and maintaining tissue homeostasis. Because of the protective effects, stem cell-derived EVs can be used to reduce oxidative stress and apoptosis in the recipient cells. In addition, EVs/exosomes have been used as directional communication tools between stem cells and parenchymal cells, giving them the ability to serve as biomarkers. Likewise, altered EVs/exosomes can be utilized for drug delivery by loading with proteins, small interfering RNAs, and viral vectors, in particular, because EVs/exosomes are able to cross the blood-brain barrier. In this review article, the properties of human induced pluripotent stem cell (iPSC)-derived EVs are discussed. The biogenesis, that is, how EVs originate in the endosomal compartment or from the cell layer of microvesicles, EV composition, the available methods of purification, and characterizations of EVs/exosomes are summarized. In particular, EVs/exosomes derived from iPSCs of different lineage specifications and the applications of these stem cell-derived exosomes in neurological diseases are discussed. Impact statement In this review, we summarized the work related to extracellular vesicles (EVs) derived from human pluripotent stem cells (hPSCs). In particular, EVs/exosomes derived from hPSCs of different lineage specifications and the applications of these stem cell-derived exosomes in neurological diseases are discussed. The results highlight the important role of cell-cell interactions in neural cellular phenotype and neurodegeneration. The findings reported in this article are significant for pluripotent stem cell-derived cell-free products toward applications in stem cell-based therapies.

A Review of Gene Therapy Delivery Systems for Intervertebral Disc Degeneration

Background: :

Intervertebral Disc (IVD) degeneration is a major public health concern, and gene therapy seems a promising approach to delay or even reverse IVD degeneration. However, the delivery system used to transfer exogenous genes into intervertebral disc cells remains a challenge.

Methods::

The MEDLINE, Web of Science, and Scopus databases were searched for English-language articles related to gene therapy for IVD degeneration articles from 1999 to May 2019. The keywords included “gene therapy” AND “intervertebral disc”. The history of the development of different delivery systems was analysed, and the latest developments in viral and non-viral vectors for IVD degeneration treatment were reviewed.

Results: :

Gene therapy delivery systems for IVD degeneration are divided into two broad categories: viral and non-viral vectors. The most commonly used viral vectors are adenovirus, adeno-associated virus (AAV), and lentivirus. Enthusiasm for the use of adenovirus vectors has gradually declined and has been replaced by a preference for lentivirus and AAV vectors. New technologies, such as RNAi and CRISPR, have further enhanced the advantage of viral vectors. Liposomes are the classic non-viral vector, and their successors, polyplex micelles and exosomes, have more potential for use in gene therapy for IVD degeneration.

Conclusion::

Lentivirus and AAV are the conventional viral vectors used in gene therapy for IVD degeneration, and the new technologies RNAi and CRISPR have further enhanced their advantages. Nonviral vectors, such as polyplex micelles and exosomes, are promising gene therapy vectors for IVD degeneration.

Lipidomics and RNA sequencing reveal a novel subpopulation of nanovesicle within extracellular matrix biomaterials

Biomaterials composed of extracellular matrix (ECM) provide both mechanical support and a reservoir of constructive signaling molecules that promote functional tissue repair. Recently, matrix-bound nanovesicles (MBVs) have been reported as an integral component of ECM bioscaffolds. Although liquid-phase extracellular vesicles (EVs) have been the subject of intense investigation, their similarity to MBV is limited to size and shape. Liquid chromatography-mass spectrometry (LC-MS)-based lipidomics and redox lipidomics were used to conduct a detailed comparison of liquid-phase EV and MBV phospholipids. Combined with comprehensive RNA sequencing and bioinformatic analysis of the intravesicular cargo, we show that MBVs are a distinct and unique subpopulation of EV and a distinguishing feature of ECM-based biomaterials. The results begin to identify the differential biologic activities mediated by EV that are secreted by tissue-resident cells and deposited within the ECM.

Clinical applications of exosome membrane proteins

Extracellular vesicles (EVs) are small membranous particles that can mediate cell-to-cell communication and which are divided into at least three categories according to their subcellular origin and size: exosomes, microvesicles, and apoptotic bodies. Exosomes are the smallest (30–150 nm) of these EVs, and play an important role in EV-mediated cell-to-cell interactions, by transferring proteins, nucleic acids and, lipids from their parental cells to adjacent or distant cells to alter their phenotypes. Most exosome studies in the past two decades have focused on their nucleic acid composition and their transfer of mRNAs and microRNAs to neighboring cells. However, exosomes also carry specific membrane proteins that can identify the physiological and pathological states of their parental cells or indicate their preferential target cells or tissues. Exosome membrane protein expression can also be directly employed or modified to allow exosomes to serve as drug delivery systems and therapeutic platforms, including in targeted therapy approaches. This review will briefly summarize information on exosome membrane proteins components and their role in exosome–cell interactions, including proteins associated with specific cell-interactions and diseases, and the potential for using exosome membrane proteins in therapeutic targeting approaches.

Plant plasma membrane vesicles interaction with keratinocytes reveals their potential as carriers

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Broccoli root vesicles showed stability and high entrapment efficiency.

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Nanoencapsulation with membrane vesicles provide an efficient system for keratinocytes cell delivery.

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Effectivity is probed by penetrating in skin layers.

During the last few years, membrane vesicles (as exovesicles) have emerged as potential nanocarriers for therapeutic applications. They are receiving attention due to their proteo-lipid nature, size, biocompatibility and biodegradability. In this work, we investigated the potential use of isolated root plasma membrane vesicles from broccoli plants as nanocarriers. For that, the entrapment efficiency and integrity of the vesicles were determined. Also, the delivery of keratinocytes and penetrability through skin were studied. The results show that the broccoli vesicles had high stability, in relation to their proteins, and high entrapment efficiency. Also, the interaction between the vesicles and keratinocytes was proven by the delivery of an encapsulated fluorescent product into cells and by the detection of plant proteins in the keratinocyte plasma membrane, showing the interactions between the membranes of two species of distinct biological kingdoms. Therefore, these results, together with the capacity of brassica vesicles to cross the skin layers, detected by fluorescent penetration, enable us to propose a type of nanocarrier obtained from natural plant membranes for use in transdermal delivery.

Chemoenzymatic Labeling of Extracellular Vesicles for Visualizing Their Cellular Internalization in Real Time

Extracellular vesicles (EVs) are intercellular communicators that are heavily implicated in diverse pathological processes. However, it is poorly understood how EVs interact with recipient cells due to the lack of appropriate tracking techniques. Here, we report a robust chemoenzymatic labeling technique for visualizing the internalization process of EVs into target cells in real time. This method uses phospholipase D (PLD) to catalyze the in situ exchange of choline by alkyne in the native EV phosphatidylcholine. Subsequent alkyne-azide click chemistry allows conjugation of Cy5 dyes for visualizing EVs internalization by confocal fluorescence microscopy. The fluorescent labeling of EVs was accomplished in an efficient and biocompatible way, without affecting both the morphology and biological activity of EVs. We applied this chemoenzymatic labeling strategy to monitor the cellular uptake of cancer cell-derived EVs in real time and to further reveal multiple internalization mechanisms. This robust, biocompatible labeling strategy provides an essential tool for EV-related studies ranging from chemical biology to drug delivery.

COVID-19 and Extracellular Vesicles: An Intriguing Interplay

BACKGROUND

The outbreak of severe acute respiratory syndrome β-coronavirus 2 (SARS-CoV-2) has the potential to become a long-lasting global health crisis. The number of people infected with the novel coronavirus has surpassed 22 million globally, resulting in over 700,000 deaths with more than 15 million people having recovered (https://covid19.who.int). Enormous efforts are underway for rapid vaccine and treatment developments. Amongst the many ways of tackling the novel coronavirus disease 2019 (COVID-19) pandemic, extracellular vesicles (EVs) are emerging.

SUMMARY

EVs are lipid bilayer-enclosed structures secreted from all types of cells, including those lining the respiratory tract. They have established roles in lung immunity and are involved in the pathogenesis of various lung diseases, including viral infection. In this review, we point out the roles and possible contribution of EVs in viral infections, as well as ongoing EV-based approaches for the treatment of COVID-19, including clinical trials. Key Messages: EVs share structural similarities to viruses and recent findings demonstrate that viruses exploit EVs for cellular exit and EVs exploit viral entry mechanisms for cargo delivery. Moreover, EV-virus interplay could be exploited for future antiviral drug and vaccine development. EV-based therapies, especially the mesenchymal stem cell-derived EVs, are being intensively studied for the treatment of COVID-19.

Protective Role of Astrocyte-Derived Exosomal microRNA-361 in Cerebral Ischemic-Reperfusion Injury by Regulating the AMPK/mTOR Signaling Pathway and Targeting CTSB

BACKGROUND

Evidence has shown that microRNAs (miRNAs) are implicated in ischemic diseases. Therefore, the aim of the present study was to identify the functions of astrocyte (ATC)-derived exosomal miR-361 on cerebral ischemic-reperfusion (I/R) injury.

METHODS

A rat model of cerebral I/R injury was initially established, followed by injection of ATC-derived exosomes. Next, the protective function of ATC-derived exosomes in rats with cerebral I/R injury was evaluated, and then the effect of miR-361 on rats with cerebral I/R injury was evaluated by changing miR-361 expression in exosomes. PC12 cells that underwent oxygen-glucose deprivation/reoxygenation were used to simulate I/R in vitro. The effect of ATC-derived exosomal miR-361 on the viability and apoptosis of OGD/R-treated PC12 cells was also assessed. The bioinformatic analysis predicted the targeted gene of miR-361.

RESULTS

It was found that I/R was damaging to the brain nerves of rats, while ATC-derived exosomal miR-361 relieved nerve damage caused by I/R. Furthermore, the in vitro experiments demonstrated that ATC-derived exosomal miR-361 increased OGD/R-inhibited PC12 cell activity and suppressed cell apoptosis. Bioinformatics predicted that miR-361 targeted cathepsin B (CTSB). CTSB upregulation blocked the protective roles of miR-361. In addition, miR-361 was found to downregulate the AMPK / mTOR signaling pathway by targeting CTSB.

CONCLUSION

The present study demonstrated that ATC-derived exosomal miR-361 alleviates nerve damage in rats with cerebral I/R injury by targeting CTSB and downregulating the AMPK/mTOR pathway. This may offer novel insights into treatment for I/R injury.

Reprogramming Exosomes for Immunotherapy

Exosomes are nanosized vesicles secreted by nearly all types of cells and play important roles in intercellular communication. Given their unique and important pharmacological properties, exosomes have been emerging as a new class of cell-free therapeutics. Herein, we describe exosomes developed against epidermal growth factor receptor (EGFR), a key factor in epithelial malignancies, involved in enhanced tumor growth, invasion, and metastasis. The exosomes are genetically modified for displaying two distinct types of monoclonal antibodies on the exosome surface, resulting in novel synthetic multivalent antibodies retargeted exosomes (SMART-Exos) that can simultaneously target tumor-associated human EGFR and T-cell surface CD3 receptor. By redirecting and activating T cells toward attacking EGFR-expressing cancer cells, the designed SMART-Exos exhibit highly potent and specific antitumor activity. In this chapter, the methodologies are outlined for generating and using SMART-Exos for cancer immunotherapy.

A comprehensive proteomics profiling identifies NRP1 as a novel identity marker of human bone marrow mesenchymal stromal cell-derived small extracellular vesicles

BACKGROUND

Clinical applications have shown extracellular vesicles (EVs) to be a major paracrine effector in therapeutic responses produced by human mesenchymal stromal/stem cells (hMSCs). As the regenerative capacity of EVs is mainly ascribed to the transfer of proteins and RNA composing its cargo, and to the activity attributed by the protein surface markers, we sought to profile the protein composition of small EVs released from hMSCs to identify hMSC-EV biomarkers with potential clinical relevance.

METHODS

Small EVs were produced and qualified from five human bone marrow MSC donors at low passage following a 48-h culture in exosome-depleted medium further processed by steps of centrifugation, filtration, and precipitation. Quantitative proteomic analysis comparing the protein profile of the EVs released from hMSCs and their parental cell was conducted using tandem mass tag labeling combined to mass spectrometry (LC-MS/MS) to identify enriched EV protein markers.

RESULTS

Nanoparticle tracking analysis showed no differences in the EV concentration and size among the five hMSC donors (1.83 × 1010 ± 3.23 × 109/mL), with the mode particle size measuring at 109.3 ± 5.7 nm. Transmission electron microscopy confirmed the presence of nanovesicles with bilayer membranes. Flow cytometric analysis identified commonly found exosomal (CD63/CD81) and hMSC (CD105/CD44/CD146) markers from released EVs in addition to surface mediators of migration (CD29 and MCSP). Quantitative proteomic identified 270 proteins significantly enriched by at least twofold in EVs released from hMSCs as compared to parental hMSCs, where neuropilin 1 (NRP1) was identified among 21 membrane-bound proteins regulating the migration and invasion of cells, as well as chemotaxis and vasculogenesis. Validation by western blot of multiple batches of EVs confirmed consistent enrichment of NRP1 in the nanovesicles released from all five hMSC donors.

CONCLUSION

The identification and verification of NRP1 as a novel enriched surface marker from multiple batches of EVs derived from multiple hMSC donors may serve as a biomarker for the assessment and measurement of EVs for therapeutic uses.

Advances on Non-Genetic Cell Membrane Engineering for Biomedical Applications

Cell-based therapeutics are very promising modalities to address many unmet medical needs, including genetic engineering, drug delivery, and regenerative medicine as well as bioimaging. To enhance the function and improve the efficacy of cell-based therapeutics, a variety of cell surface engineering strategies (genetic engineering and non-genetic engineering) are developed to modify the surface of cells or cell-based therapeutics with some therapeutic molecules, artificial receptors, and multifunctional nanomaterials. In comparison to complicated procedures and potential toxicities associated with genetic engineering, non-genetic engineering strategies have emerged as a powerful and compatible complement to traditional genetic engineering strategies for enhancing the function of cells or cell-based therapeutics. In this review, we will first briefly summarize key non-genetic methodologies including covalent chemical conjugation (surface reactive groups-direct conjugation, and enzymatically mediated and metabolically mediated indirect conjugation) and noncovalent physical bioconjugation (biotinylation, electrostatic interaction, and lipid membrane fusion as well as hydrophobic insertion), which have been developed to engineer the surface of cell-based therapeutics with various materials. Next, we will comprehensively highlight the latest advances in non-genetic cell membrane engineering surrounding different cells or cell-based therapeutics, including whole-cell-based therapeutics, cell membrane-derived therapeutics, and extracellular vesicles. Advances will be focused specifically on cells that are the most popular types in this field, including erythrocytes, platelets, cancer cells, leukocytes, stem cells, and bacteria. Finally, we will end with the challenges, future trends, and our perspectives of this relatively new and fast-developing research field.

Genetically Engineered Cell-Derived Nanoparticles for Targeted Breast Cancer Immunotherapy

Exosomes are nanosized membranous vesicles secreted by a variety of cells. Due to their unique and pharmacologically important properties, cell-derived exosome nanoparticles have drawn significant interest for drug development. By genetically modifying exosomes with two distinct types of surface-displayed monoclonal antibodies, we have developed an exosome platform termed synthetic multivalent antibodies retargeted exosome (SMART-Exo) for controlling cellular immunity. Here, we apply this approach to human epidermal growth factor receptor 2 (HER2)-expressing breast cancer by engineering exosomes through genetic display of both anti-human CD3 and anti-human HER2 antibodies, resulting in SMART-Exos dually targeting T cell CD3 and breast cancer-associated HER2 receptors. By redirecting and activating cytotoxic T cells toward attacking HER2-expressing breast cancer cells, the designed SMART-Exos exhibited highly potent and specific anti-tumor activity both in vitro and in vivo. This work demonstrates preclinical feasibility of utilizing endogenous exosomes for targeted breast cancer immunotherapy and the SMART-Exos as a broadly applicable platform technology for the development of next-generation immuno-nanomedicines.

Stem cell-derived extracellular vesicles: role in oncogenic processes, bioengineering potential, and technical challenges

Extracellular vesicles (EVs) are cellular-derived versatile transporters with a specialized property for trafficking a variety of cargo, including metabolites, growth factors, cytokines, proteins, lipids, and nucleic acids, throughout the microenvironment. EVs can act in a paracrine manner to facilitate communication between cells as well as modulate immune, inflammatory, regenerative, and remodeling processes. Of particular interest is the emerging association between EVs and stem cells, given their ability to integrate complex inputs for facilitating cellular migration to the sites of tissue injury. Additionally, stem cell-derived EVs can also act in an autocrine manner to influence stem cell proliferation, mobilization, differentiation, and self-renewal. Hence, it has been postulated that stem cells and EVs may work synergistically in the process of tissue repair and that dysregulation of EVs may cause a loss of homeostasis in the microenvironment leading to disease. By harnessing the property of EVs for delivery of small molecules, stem cell-derived EVs possess significant potential as a platform for developing bioengineering approaches for next-generation cancer therapies and targeted drug delivery methods. Although one of the main challenges of clinical cancer treatment remains a lack of specificity for the delivery of effective treatment options, EVs can be modified via genetic, biochemical, or synthetic methods for enhanced targeting ability of chemotherapeutic agents in promoting tumor regression. Here, we summarize recent research on the bioengineering potential of EV-based cancer therapies. A comprehensive understanding of EV modification may provide a novel strategy for cancer therapy and for the utilization of EVs in the targeting of oncogenic processes. Furthermore, innovative and emerging new technologies are shifting the paradigm and playing pivotal roles by continually expanding novel methods and materials for synthetic processes involved in the bioengineering of EVs for enhanced precision therapeutics.

Neural stem cell transplantation therapy for brain ischemic stroke: Review and perspectives

Brain ischemic stroke is one of the most common causes of death and disability, currently has no efficient therapeutic strategy in clinic. Due to irreversible functional neurons loss and neural tissue injury, stem cell transplantation may be the most promising treatment approach. Neural stem cells (NSCs) as the special type of stem cells only exist in the nervous system, can differentiate into neurons, astrocytes, and oligodendrocytes, and have the abilities to compensate insufficient endogenous nerve cells and improve the inflammatory microenvironment of cell survival. In this review, we focused on the important role of NSCs therapy for brain ischemic stroke, mainly introduced the methods of optimizing the therapeutic efficacy of NSC transplantation, such as transfection and overexpression of specific genes, pretreatment of NSCs with inflammatory factors, and co-transplantation with cytokines. Next, we discussed the potential problems of NSC transplantation which seriously limited their rapid clinical transformation and application. Finally, we expected a new research topic in the field of stem cell research. Based on the bystander effect, exosomes derived from NSCs can overcome many of the risks and difficulties associated with cell therapy. Thus, as natural seed resource of nervous system, NSCs-based cell-free treatment is a newly therapy strategy, will play more important role in treating ischemic stroke in the future.

Rapid On-Demand Extracellular Vesicle Augmentation with Versatile Oligonucleotide Tethers

Exosomes show potential as ideal vehicles for drug delivery because of their natural role in transferring biological cargo between cells. However, current methods to engineer exosomes without negatively impacting their function remain challenging. Manipulating exosome-secreting cells is complex and time-consuming, while direct functionalization of exosome surface proteins suffers from low specificity and low efficiency. We demonstrate a rapid, versatile, and scalable method with oligonucleotide tethers to enable diverse surface functionalization on both human and murine exosomes. These exosome surface modifiers, which range from reactive functional groups and small molecules to aptamers and large proteins, can readily and efficiently enhance native exosome properties. We show that cellular uptake of exosomes can be specifically altered with a tethered AS1411 aptamer, and targeting specificity can be altered with a tethered protein. We functionalize exosomes with an immunomodulatory protein, FasL, and demonstrate their biological activity both in vitro and in vivo. FasL-functionalized exosomes, when bioprinted on a collagen matrix, allows spatial induction of apoptosis in tumor cells and, when injected in mice, suppresses proliferation of alloreactive T cells. This oligonucleotide tethering strategy is independent of the exosome source and further circumvents the need to genetically modify exosome-secreting cells.

Nanostructured Modulators of Neuroglia

Biological and synthetic nanostructures can influence both glia and neurons in the central nervous system. Neurons represent only a small proportion (about 10%) of cells in the brain, whereas glial cells are the most abundant cell type. Non-targeted nanomedicines are mainly internalized by glia, in particular microglia, and to a lesser extent by astrocytes. Internalized nanomedicines by glia indirectly modify the functional status of neurons. The mechanisms of biochemical, morphological and functional changes of neural cells exposed to nanomedicines are still not well-understood. This minireview provides a cross-section of morphological and biochemical changes in glial cells and neurons exposed to different classes of hard and soft nanostructures.

The potential of exosomes in the therapy of the cartilage and bone complications; emphasis on osteoarthritis

Osteoarthritis is a prevalent worldwide joint disease, which demonstrates a remarkable adverse effect on the patients' life modality. Medicinal agents, exclusively nonsteroidal anti-inflammatory drugs (NSAIDs), have been routinely applied in the clinic. But, their effects are restricted to pain control with insignificant effects on cartilage renovation, which would finally lead to cartilage destruction. In the field of regenerative medicine, many researchers have tried to use stem cells to repair tissues and other human organs. However, in recent years, with the discovery of extracellular microvesicles, especially exosomes, researchers have been able to offer more exciting alternatives on the subject. Exosomes and microvesicles are derived from different types of bone cells such as mesenchymal stem cells, osteoblasts, and osteoclasts. They are also recognized to play substantial roles in bone remodeling processes including osteogenesis, osteoclastogenesis, and angiogenesis. Specifically, exosomes derived from a mesenchymal stem cell have shown a great potential for the desired purpose. Exosomal products include miRNA, DNA, proteins, and other factors. At present, if it is possible to extract exosomes from various stem cells effectively and load certain products or drugs into them, they can be used in diseases, such as rheumatoid arthritis, osteoarthritis, bone fractures, and other diseases. Of course, to achieve proper clinical use, advances have to be made to establish a promising regenerative ability for microvesicles for treatment purposes in the orthopedic disorders. In this review, we describe the exosomes biogenesis and bone cell derived exosomes in the regenerate process of bone and cartilage remodeling.

Functional extracellular vesicles engineered with lipid-grafted hyaluronic acid effectively reverse cancer drug resistance

Multidrug resistance (MDR) is a key issue accounting for ineffectiveness of cancer chemotherapy. Numerous multifunctional nanocarriers have been developed to increase drug delivery efficacy and inhibit drug efflux for overcoming cancer drug resistance. However, limited success has been achieved in clinic because of nanocarriers' complicated multi-step fabrication procedures and their undesired side toxicity as well as potential immunogenicity. Here, hyaluronic acid (HA) functionalized extracellular vesicles (EVs) are generated as natural vehicles to efficiently deliver doxorubicin (DOX) and reverse MDR. The EVs isolated from noncancerous HEK293T cells (hEVs) reduce P-glycoprotein (P-gp) expression in drug resistant MCF7/ADR cells. To acquire tumor-targeting capability, hEVs are modified with lipidomimetic chains-grafted HA (lipHA) by a simple incubation. Owing to CD44-mediated cancer-specific targeting and P-gp suppressive capability, the HA-functionalized hEVs (lipHA-hEVs) remarkably promote the intracellular DOX accumulation in drug resistant breast cancer cells. In preclinical MDR tumor models, lipHA-hEVs deeply penetrate into tumor tissue and effectively transport DOX into tumor local, while eliminating DOX's systemic toxicity. Importantly, DOX@lipHA-hEVs inhibited MDR tumor growth by 89% and extend animal survival time by approximately 50%. Thus, our engineered tumor-targeting hEVs are promising natural carriers for overcoming cancer MDR.

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.

Exosomes derived from miR-375-overexpressing human adipose mesenchymal stem cells promote bone regeneration

OBJECTIVES

The present study aimed to investigate whether exosomes derived from miR-375-overexpressing human adipose mesenchymal stem cells (hASCs) could enhance bone regeneration.

MATERIALS AND METHODS

Exosomes enriched with miR-375 (Exo [miR-375]) were generated from hASCs stably overexpressing miR-375 after lentiviral transfection and identified with transmission electron microscopy, nanosight and western blotting. The construction efficiency of Exo (miR-375) was evaluated with qRT-PCR and incubated with human bone marrow mesenchymal stem cells (hBMSCs) to optimize the effective dosage. Then, the osteogenic capability of Exo (miR-375) was investigated with ALP and ARS assays. Furthermore, dual-luciferase reporter assay and western blotting were conducted to reveal the underlying mechanism of miR-375 in osteogenic regulation. Finally, Exo (miR-375) were embedded with hydrogel and applied to a rat model of calvarial defect, and μ-CT analysis and histological examination were conducted to evaluate the therapeutic effects of Exo (miR-375) in bone regeneration.

RESULTS

miR-375 could be enriched in exosomes by overexpressing in the parent cells. Administration of Exo (miR-375) at 50 μg/mL improved the osteogenic differentiation of hBMSCs. With miR-375 absorbed by hBMSCs, insulin-like growth factor binding protein 3 (IGFBP3) was inhibited by binding to its 3'UTR, and recombinant IGFBP3 protein reduced the osteogenic effects triggered by Exo (miR-375). After incorporated with hydrogel, Exo (miR-375) displayed a slow and controlled release, and further in vivo analysis demonstrated that Exo (miR-375) enhanced the bone regenerative capacity in a rat model of calvarial defect.

CONCLUSIONS

Taken together, our study demonstrated that exosomes derived from miR-375-overexpressing hASCs promoted bone regeneration.

Human CAP cells represent a novel source for functional, miRNA-loaded exosome production

Exosomes represent a promising delivery tool for nucleic acid-based pharmaceuticals. They are highly suitable for transporting therapeutic miRNAs to tumor cells, due to their natural membrane components. Further, exosomes are capable of effectively protecting nucleic acids against ribonucleases and enable the delivery of their content through cell membranes. However, no suitable production host for miRNA containing exosomes of non-tumorigenic origin has yet been identified. In this study we engineered an immortalised human amniocyte cell line (CAP^® cells), whose exosomes were enriched and characterised. The cell line modifications not only enabled the production of GFP-labelled but also pro-apoptotic miRNA containing exosomes without negative influence on host cell growth. Furthermore, we demonstrated that pro-apoptotic miRNA containing CAP exosomes are taken up by ovarian cancer cells. Strikingly, delivery of functional exosomal miRNA led to downregulation of several reported target genes in the treated tumor cells. In summary, we revealed CAP cells of non-tumorigenic origin as a novel and efficient exosome production host with the potential to produce functional miRNA-loaded exosomes.

Strategies for the use of Extracellular Vesicles for the Delivery of Therapeutics

Extracellular vesicles (EVs) are nanosized, membrane-bound vesicles released from eukaryotic and prokaryotic cells that can transport cargo containing DNA, RNA, lipids and proteins, between cells as a means of intercellular communication. Although EVs were initially considered to be cellular debris deprived of any essential biological functions, emerging literature highlights the critical roles of EVs in the context of intercellular signaling, maintenance of tissue homeostasis, modulation of immune responses, inflammation, cancer progression, angiogenesis, and coagulation under both physiological and pathological states. Based on the ability of EVs to shuttle proteins, lipids, carbohydrates, mRNAs, long non-coding RNAs (lncRNAs), microRNAs, chromosomal DNA, and mitochondrial DNA into target cells, the presence and content of EVs in biofluids have been exploited for biomarker research in the context of diagnosis, prognosis and treatment strategies. Additionally, owing to the characteristics of EVs such as stability in circulation, biocompatibility as well as low immunogenicity and toxicity, these vesicles have become attractive systems for the delivery of therapeutics. More recently, EVs are increasingly being exploited as conduits for delivery of therapeutics for anticancer strategies, immunomodulation, targeted drug delivery, tissue regeneration, and vaccination. In this review, we highlight and discuss the multiple strategies that are employed for the use of EVs as delivery vehicles for therapeutic agents, including the potential advantages and challenges involved. Graphical abstract.

Clinical implications of extracellular vesicles in neurodegenerative diseases

Introduction: Extracellular vesicles (EVs) released by neural cells play a crucial role in intracellular communication in both physiological and pathological states. Recent studies have shown that the neuropathogenic manifestation of many progressive nervous system diseases including Parkinson's disease (PD), Alzheimer's diseases (AD), and amyotrophic lateral sclerosis (ALS). These diseases are frequently found to be associated with the accumulation of misfolded proteins, exploit EVs for the spread of aggregates to naive cells in a prion-like mechanism. Therefore, characterization of EVs and understanding their mechanism of action could open a window of opportunity to discover biomarkers and therapeutic targets in a disease-specific manner. Areas covered: In this review, we discuss the role of neural cells-derived EVs in normal and disease states. We also highlight their biomedical potential in modern medicine, including the use of circulating EVs as biomarkers for diagnosis with a special focus on newly-identified potential biomarkers in neurodegenerative disease, and novel methodologies in EVs isolation. Expert opinion: Systematic and comprehensive analysis of EVs in different biofluid sources is needed. Considering the potential for tremendous clinical benefits of EVs research in neurodegenerative disease, there is also an urgent need to standardize neural cells-derived EV enrichment protocols for consensus results.

Nanoparticle technology and stem cell therapy team up against neurodegenerative disorders

The convergence of nanoparticles and stem cell therapy holds great promise for the study, diagnosis, and treatment of neurodegenerative disorders. Researchers aim to harness the power of nanoparticles to regulate cellular microenvironment, improve the efficiency of cell and drug delivery to the brain, and enhance the survival of stem cell transplants. Understanding the various properties of different nanoparticles is key to applying them to clinical therapies; the many distinct types of nanoparticles offer unique capacities for medical imaging, diagnosis, and treatment of neurodegeneration disorders. In this review we introduce the biology of Alzheimer's, Parkinson's Disease, and amyotrophic lateral sclerosis, and discuss the potentials and shortcomings of metal, silica, lipid-based, polymeric, and hydrogel nanoparticles for diagnosis and treatment of neurodegenerative disorders. We then provide an overview of current strategies in stem cell therapies and how they can be combined with nanotechnology to improve clinical outcomes.

FZD10 Carried by Exosomes Sustains Cancer Cell Proliferation

Extracellular vesicles (EVs) are involved in intercellular communication during carcinogenesis, and cancer cells are able to secrete EVs, in particular exosomes containing molecules, that can be transferred to recipient cells to induce pathological processes and significant modifications, as metastasis, increase of proliferation, and carcinogenesis evolution. FZD proteins, a family of receptors comprised in the Wnt signaling pathway, play an important role in carcinogenesis of the gastroenteric tract. Here, a still unknown role of Frizzled 10 (FZD10) protein was identified. In particular, the presence of FZD10 and FZD10-mRNA in exosomes extracted from culture medium of the untreated colorectal, gastric, hepatic, and cholangio cancer cell lines, was detected. A substantial reduction in the FZD10 and FZD10-mRNA level was achieved in FZD10-mRNA silenced cells and in their corresponding exosomes. Concomitantly, a significant decrease in viability of the silenced cells compared to their respective controls was observed. Notably, the incubation of silenced cells with the exosomes extracted from culture medium of the same untreated cells promoted the restoration of the cell viability and, also, of the FZD10 and FZD10-mRNA level, thus indicating that the FZD10 and FZD10-mRNA delivering exosomes may be potential messengers of cancer reactivation and play an active role in long-distance metastatization.

Scalable Production and Isolation of Extracellular Vesicles: Available Sources and Lessons from Current Industrial Bioprocesses

Potential applications of extracellular vesicles (EVs) are attracting increasing interest in the fields of medicine, cosmetics, and nutrition. However, the manufacturing of EVs is currently characterized by low yields. This limitation severely hampers progress in research at the laboratory and clinical scales, as well as the realization of successful and cost-effective EV-based products. Moreover, the high level of heterogeneity of EVs further complicates reproducible manufacturing on a large scale. In this review, possible directions toward the scalable production of EVs are discussed. In particular, two strategies are considered: i) the optimization of upstream unit operations and ii) the exploitation of well-established and mature technologies already in use in other industrial bioprocesses.

Cancer Immunotherapy Based on Natural Killer Cells: Current Progress and New Opportunities

Cancer immunotherapy has been firmly established as a new milestone for cancer therapy, with the development of multiple immune cells as therapeutic tools. Natural killer (NK) cells are innate immune cells endowed with potent cytolytic activity against tumors, and meanwhile act as regulatory cells for the immune system. The efficacy of NK cell-mediated immunotherapy can be enhanced by immune stimulants such as cytokines and antibodies, and adoptive transfer of activated NK cells expanded ex vivo. In addition, NK cells can arm themselves with chimeric antigen receptors (CARs), which may greatly enhance their anti-tumor activity. Most recently, extracellular vesicles (EVs) derived from NK cells show promising anti-tumor effects in preclinical studies. Herein, we carefully review the current progress in these NK cell-based immunotherapeutic strategies (NK cells combined with stimulants, adoptive transfer of NK cells, CAR-NK cells, and NK EVs) for the treatment of cancers, and discussed the challenges and opportunities for opening a new horizon for cancer immunotherapy.

Crucial Role of Extracellular Vesicles in Bronchial Asthma

Extracellular vesicles (EVs) are circulating vesicles secreted by various cell types. EVs are classified into three groups according to size, structural components, and generation process of vesicles: exosomes, microvesicles, and apoptotic bodies. Recently, EVs have been considered to be crucial for cell-to-cell communications and homeostasis because they contain intracellular proteins and nucleic acids. Epithelial cells from mice suffering from bronchial asthma (BA) secrete more EVs and suppress inflammation-induced EV production. Moreover, microarray analyses of bronchoalveolar lavage fluid have revealed that several microRNAs are useful novel biomarkers of BA. Mesenchymal stromal cell-derived EVs are possible candidates of novel BA therapy. In this review, we highlight the biologic roles of EVs in BA and review novel EV-targeted therapy to help understanding by clinicians and biologists.

Extracellular Vesicles Suppress Basal and Lipopolysaccharide-Induced NFκB Activity in Human Periodontal Ligament Stem Cells

Periodontitis is an infectious disease characterized by chronic inflammation and progressive destruction of periodontal tissues. Chronic inflammatory environment may affect immunomodulatory function of periodontal ligament stem cells (PDLSCs) and promote shift toward proinflammatory phenotype contributing to propagation of periodontitis. Therefore, suppression of inflammatory response in PDLSCs represents a novel therapeutic approach. Extracellular vesicles (EVs) have been shown to display anti-inflammatory and immunosuppressive actions in different tissues and could represent a potent therapeutic tools against chronic inflammation during periodontitis. In the present study, we investigated the effects of EVs on the basal and lipopolysaccharide (LPS)-induced activity of NFκB signaling pathway in PDLSCs. We also examined the impact of EVs on the osteogenic differentiation and expression of osteogenesis-related genes. EVs were purified by differential ultracentrifugation from PDLSCs grown on gelatin-coated alginate microcarriers in a bioreactor. NFκB reporter assays demonstrated that EVs permanently suppressed basal and LPS-induced activity of NFκB in PDLSCs. Combined treatment with EVs and anti-TLR4 antibody (Ab) resulted in attenuation of the inhibitory effect on the NFκB activity, suggesting a possible interference through a competition for TLR4 signaling pathway. EVs also increased phosphorylation of Akt and its downstream target GSK3β (Ser 9) indicating that PI3K/Akt signaling pathway may act as suppressor of NFκB activity. LPS stimulated osteogenic mineralization of PDLSCs. Unexpectedly, anti-TLR4 blocking Ab per se significantly decreased osteogenic mineralization of PDLSCs. EVs did not affect osteogenic mineralization, but partially suppressed inhibitory effect of anti-TLR4 blocking Ab. Gene expression studies revealed significant effects of EVs on osteogenesis-related genes and possible interference with TLR4 signaling in PDLSCs. In conclusion, our study demonstrates that EVs suppress basal and LPS-induced activity of NFκB signaling pathway in PDLSCs and could potentially be used for targeting of chronic inflammation during periodontitis.

Exosomes from Microglia Attenuate Photoreceptor Injury and Neovascularization in an Animal Model of Retinopathy of Prematurity

The role of microglia in the pathophysiology of ischemic retinal diseases has been studied extensively. Exosomes from microglial cells exert protective effects during several nervous system diseases, but their roles in hypoxia-induced retinopathy remain unclear. In our study, exosomes derived from microglial cells were injected into the vitreous body of mice with oxygen-induced retinopathy (OIR). Results showed that exosome-treated OIR mice exhibited smaller avascular areas and fewer neovascular tufts in addition to decreased vascular endothelial growth factor (VEGF) and transforming growth factor β (TGF-β) expression. Moreover, photoreceptor apoptosis was suppressed by exosome injection. Mechanistically, exosomes from microglial cells were incorporated into photoreceptors in vitro and inhibited the inositol-requiring enzyme 1α (IRE1α)-X-box binding protein 1 (XBP1) cascade, which contributes to hypoxia-induced photoreceptor apoptosis. Furthermore, the exosomes also downregulated the mRNA and protein levels of VEGF and TGF-β in hypoxia-exposed photoreceptors. A microRNA assay showed that microRNA-24-3p (miR-24-3p) levels were extremely high in exosomes from microglial cells, suggesting that this could be the key molecule that inhibits the hypoxia-induced expression of IRE1α in photoreceptors. These findings delineate a novel exosome-mediated mechanism of microglial cell-photoreceptor crosstalk that facilitates normal angiogenesis and visual function in OIR mice; thus, our results also suggest a potential therapeutic approach for retinopathy of prematurity.

Physical Structuring of Injectable Polymeric Systems to Controllably Deliver Nanosized Extracellular Vesicles

Extracellular vesicles (EVs) are emerging as a promising alternative approach to cell-therapies. However, to realize the potential of these nanoparticles as new regenerative tools, healthcare materials that address the current limitations of systemic administration need to be developed. Here, two technologies for controlling the structure of alginate based microgel suspensions are used to develop sustained local release of EVs, in vitro. Microparticles formed using a shearing technique are compared to those manufactured using vibrational technology, resulting in either anisotropic sheet-like or spheroid particles, respectively. EVs harvested from preosteoblasts are isolated using differential ultracentrifugation and successfully loaded into the two systems, while maintaining their structures. Promisingly, in addition to exhibiting even EV distribution and high stability, controlled release of vesicles from both structures is exhibited, in vitro, over the 12 days studied. Interestingly, a significantly greater number of EVs are released from the suspensions formed by shearing (69.9 ± 10.5%), compared to the spheroids (35.1 ± 7.6%). Ultimately, alterations to the hydrogel physical structures have shown to tailor nanoparticle release while simultaneously providing ideal material characteristics for clinical injection. Thus, the sustained release mechanisms achieved through manipulating the formation of such biomaterials provide a key to unlocking the therapeutic potential held within EVs.

Cushioned-Density Gradient Ultracentrifugation (C-DGUC) improves the isolation efficiency of extracellular vesicles

Ultracentrifugation (UC) is recognized as a robust approach for the isolation of extracellular vesicles (EVs). However, recent studies have highlighted limitations of UC including low recovery efficiencies and aggregation of EVs that could impact downstream functional analyses. We tested the benefit of using a liquid cushion of iodixanol during UC to address such shortcomings. In this study, we compared the yield and purity of EVs isolated from J774A.1 macrophage conditioned media by conventional UC and cushioned-UC (C-UC). We extended our study to include two other common EV isolation approaches: ultrafiltration (UF) and polyethylene glycol (PEG) sedimentation. After concentrating EVs using these four methods, the concentrates underwent further purification by using OptiPrep density gradient ultracentrifugation (DGUC). Our data show that C-DGUC provides a two-fold improvement in EV recovery over conventional UC-DGUC. We also found that UF-DGUC retained ten-fold more protein while PEG-DGUC achieved similar performance in nanoparticle and protein recovery compared to C-DGUC. Regarding purity as assessed by nanoparticle to protein ratio, our data show that EVs isolated by UC-DGUC achieved the highest purity while C-DGUC and PEG-DGUC led to similarly pure preparations. Collectively, we demonstrate that the use of a high-density iodixanol cushion during the initial concentration step improves the yield of EVs derived from cell culture media compared to conventional UC. This enhanced yield without substantial retention of protein contaminants and without exposure to forces causing aggregation offers new opportunities for the isolation of EVs that can subsequently be used for functional studies.

Human Amniotic Epithelial Cell-Derived Exosomes Restore Ovarian Function by Transferring MicroRNAs against Apoptosis

Premature ovarian failure (POF) is one of the most common complications among female patients with tumors treated with chemotherapy and requires advanced treatment strategies. Human amniotic epithelial cell (hAEC)-based therapy mediates tissue regeneration in a variety of diseases, and increasing evidence suggests that the therapeutic efficacy of hAECs mainly depends on paracrine action. This study aimed to identify exosomes derived from hAECs and explored the therapeutic potential in ovaries damaged by chemotherapy and the underlying molecular mechanism. hAEC-derived exosomes exhibited a cup- or sphere-shaped morphology with a mean diameter of 100 nm and were positive for Alix, CD63, and CD9. hAEC exosomes increased the number of follicles and improved ovarian function in POF mice. During the early stage of transplantation, hAEC exosomes significantly inhibited granulosa cell apoptosis, protected the ovarian vasculature from damage, and were involved in maintaining the number of primordial follicles in the injured ovaries. Enriched microRNAs (miRNAs) existed in hAEC exosomes, and target genes were enriched in phosphatidylinositol signaling and apoptosis pathways. Studies in vitro demonstrated that hAEC exosomes inhibited chemotherapy-induced granulosa cell apoptosis via transferring functional miRNAs, such as miR-1246. Our findings demonstrate that hAEC-derived exosomes have the potential to restore ovarian function in chemotherapy-induced POF mice by transferring miRNAs.

Targeted Drug Delivery in Lipid-like Nanocages and Extracellular Vesicles

The possibility of targeted drug delivery to a specific tissue, organ, or cell has opened new promising avenues in treatment development. The technology of targeted delivery aims to create multifunctional carriers that are capable of long circulation in the patient's organism and possess low toxicity at the same time. The surface of modern synthetic carriers has high structural similarity to the cell membrane, which, when combined with additional modifications, also promotes the transfer of biological properties in order to penetrate physiological barriers effectively. Along with artificial nanocages, further efforts have recently been devoted to research into extracellular vesicles that could serve as natural drug delivery vehicles. This review provides a detailed description of targeted delivery systems that employ lipid and lipid-like nanocages, as well as extracellular vesicles with a high level of biocompatibility, highlighting genetically encoded drug delivery vehicles.

Exosomal delivery of doxorubicin enables rapid cell entry and enhanced in vitro potency

Doxorubicin is a chemotherapeutic agent that is commonly used to treat a broad range of cancers. However, significant cardiotoxicity, associated with prolonged exposure to doxorubicin, limits its continued therapeutic use. One strategy to prevent the uptake of doxorubicin into cardiac cells is the encapsulation of the drug to prevent non-specific uptake and also to improve the drugs’ pharmacokinetic properties. Although encapsulated forms of doxorubicin limit the cardiotoxicity observed, they are not without their own liabilities as an increased amount of drug is deposited in the skin where liposomal doxorubicin can cause palmar-plantar erythrodysesthesia. Exosomes are small endogenous extracellular vesicles, that transfer bioactive material from one cell to another, and are considered attractive drug delivery vehicles due to their natural origin. In this study, we generated doxorubicin-loaded exosomes and demonstrate their rapid cellular uptake and re-distribution of doxorubicin from endosomes to the cytoplasm and nucleus resulting in enhanced potency in a number of cultured and primary cell lines when compared to free doxorubicin and liposomal formulations of doxorubicin. In contrast to other delivery methods for doxorubicin, exosomes do not accumulate in the heart, thereby providing potential for limiting the cardiac side effects and improved therapeutic index.

Effect of MSCs and MSC-Derived Extracellular Vesicles on Human Blood Coagulation

Mesenchymal stem cells (MSCs) have emerged as a potent therapeutic tool for the treatment of a number of pathologies, including immune pathologies. However, unwelcome effects of MSCs on blood coagulation have been reported, motivating us to explore the thrombotic properties of human MSCs from the umbilical cord. We revealed strong procoagulant effects of MSCs on human blood and platelet-free plasma using rotational thromboelastometry and thrombodynamic tests. A similar potentiation of clotting was demonstrated for MSC-derived extracellular vesicles (EVs). To offer approaches to avoid unwanted effects, we studied the impact of a heparin supplement on MSC procoagulative properties. However, MSCs still retained procoagulant activity toward blood from children receiving a therapeutic dose of unfractionated heparin. An analysis of the mechanisms responsible for the procoagulant effect of MSCs/EVs revealed the presence of tissue factor and other proteins involved in coagulation-associated pathways. Also, we found that some MSCs and EVs were positive for annexin V, which implies the presence of phosphatidylserine on their surfaces, which can potentiate clot formation. Thus, we revealed procoagulant activity of MSCs/EVs associated with the presence of phosphatidylserine and tissue factor, which requires further analysis to avoid adverse effects of MSC therapy in patients with a risk of thrombosis.

Mesenchymal Stromal Cell Derived Extracellular Vesicles Reduce Hypoxia-Ischaemia Induced Perinatal Brain Injury

BACKGROUND

Neonatal hypoxic-ischemic (HI) insult is a leading cause of disability and death in newborns, with therapeutic hypothermia being the only currently available clinical intervention. Thus there is a great need for adjunct and novel treatments for enhanced or alternative post-HI neuroprotection. Extracellular vesicles (EVs) derived from mesenchymal stromal/stem cells (MSCs) have recently been shown to exhibit regenerative effects in various injury models. Here we present findings showing neuroprotective effects of MSC-derived EVs in the Rice-Vannucci model of severe HI-induced neonatal brain insult.

METHODS

Mesenchymal stromal/stem cell-derived EVs were applied intranasally immediately post HI-insult and behavioral outcomes were observed 48 h following MSC-EV treatment, as assessed by negative geotaxis. Brains were thereafter excised and assessed for changes in glial responses, cell death, and neuronal loss as markers of damage at 48 h post HI-insult.

RESULTS

Brains of the MSC-EV treated group showed a significant decrease in microglial activation, cell death, and percentage tissue volume loss in multiple brain regions, compared to the control-treated groups. Furthermore, negative geotaxis test showed improved behavioral outcomes at 48 h following MSC-EV treatment.

CONCLUSION

Our findings highlight the clinical potential of using MSC-derived EVs following neonatal hypoxia-ischaemia.

Cannabidiol Affects Extracellular Vesicle Release, miR21 and miR126, and Reduces Prohibitin Protein in Glioblastoma Multiforme Cells

Glioblastoma multiforme (GBM) is the most common and aggressive form of primary malignant brain tumor in adults, with poor prognosis. Extracellular vesicles (EVs) are key-mediators for cellular communication through transfer of proteins and genetic material. Cancers, such as GBM, use EV release for drug-efflux, pro-oncogenic signaling, invasion and immunosuppression; thus the modulation of EV release and cargo is of considerable clinical relevance. As EV-inhibitors have been shown to increase sensitivity of cancer cells to chemotherapy, and we recently showed that cannabidiol (CBD) is such an EV-modulator, we investigated whether CBD affects EV profile in GBM cells in the presence and absence of temozolomide (TMZ). Compared to controls, CBD-treated cells released EVs containing lower levels of pro-oncogenic miR21 and increased levels of anti-oncogenic miR126; these effects were greater than with TMZ alone. In addition, prohibitin (PHB), a multifunctional protein with mitochondrial protective properties and chemoresistant functions, was reduced in GBM cells following 1 h CBD treatment. This data suggests that CBD may, via modulation of EVs and PHB, act as an adjunct to enhance treatment efficacy in GBM, supporting evidence for efficacy of cannabinoids in GBM.

Exosomes from M1-Polarized Macrophages Enhance Paclitaxel Antitumor Activity by Activating Macrophages-Mediated Inflammation

Objective: Exosomes (Exos) are membrane-encased vesicles derived by nearly all cell types for intercellular communication and regulation. They also received attention for their use as natural therapeutic platforms and drug delivery system. Classically activated M1 macrophages suppress tumor growth by releasing pro-inflammatory factors. This study investigated the suitability of M1-exosomes (M1-Exos) as drug carrier and their effect on the NF-κB signal pathway and further detected whether macrophages repolarization can potentiate the antitumor activities of chemotherapeutics. Methods: M1-Exos were isolated from M1-macrophages by ultracentrifugation and characterized by transmission electron, nanoparticle tracking analysis, dynamic light scattering and western blot. Then M1-Exos were used as Paclitaxel (PTX) carriers to prepare a nano-formulation (PTX- M1-Exos). A relatively simple slight sonication method was used to prepare the drug delivery system (PTX-M1-Exos). The cytotoxicity of PTX-M1-Exos on cancer cells was detected by MTT and flow cytometry in vitro. 4T1 tumor bearing mice were used to perform the therapeutic effect of PTX-M1-Exos in vivo. Results: The expression of caspase-3 in breast cancer cells was increased when co-incubated with macrophages in the presence of M1-Exos in vitro. The production of pro-inflammatory cytokines was increased after exposure of macrophages in M1-Exos. M1-Exos provided a pro-inflammatory environment which enhanced the anti-tumor activity via caspase-3 mediated pathway. The treatment of M1-Exos to the tumor bearing mice exhibit anti-tumor effects in vivo. Meanwhile, the treatment of PTX-M1-Exos demonstrated higher anti-tumor effects than the M1-Exos or PTX group. Conclusion: The results in our study indicate that the M1-Exos act as the carrier to deliver PTX into the tumor tissues, and also enhance the anti-tumor effects of chemotherapeutics in tumor bearing mice.

Adipose-derived exosomes: A novel adipokine in obesity-associated diabetes

Dysfunction of the adipose tissue is a central driver for obesity-associated diabetes. It is characterized by dysregulated adipokine secretion, which contributes to insulin resistance of key metabolic tissues, including the liver, skeletal muscles, and fat itself. The inter-organ cross talk between the adipose tissue and the other organs as well as the intra-organ cross talk between adipocytes and macrophages within the adipose tissue, traditionally mediated by hormones, was recently evidenced to be regulated by adipose-derived exosomes. Exosomes are nano-sized membrane-bound vesicles secreted by the donor cells to modify intercellular communication by translating constituent nucleic acids and proteins to the target cells. Herein, we reviewed the latest progress in understanding the role of adipose-derived exosomes in the development of insulin resistance, a key mechanism that underpins diabetes and diabetic complications, with a special focus on the role of exosomal miRNAs (micro RNAs) and proteins, and discusses the potential implications of targeting adipose tissue-derived exosomes for diabetic therapeutics.

Stem Cell-Derived Extracellular Vesicles for Treating Joint Injury and Osteoarthritis

Extracellular vesicles (EVs) are nanoscale particles secreted by almost all cell types to facilitate intercellular communication. Stem cell-derived EVs theoretically have the same biological functions as stem cells, but offer the advantages of small size, low immunogenicity, and removal of issues such as low cell survival and unpredictable long-term behaviour associated with direct cell transplantation. They have been an area of intense interest in regenerative medicine, due to the potential to harness their anti-inflammatory and pro-regenerative effects to induce healing in a wide variety of tissues. However, the potential of using stem cell-derived EVs for treating joint injury and osteoarthritis has not yet been extensively explored. The pathogenesis of osteoarthritis, with or without prior joint injury, is not well understood, and there is a longstanding unmet clinical need to develop new treatments that provide a therapeutic effect in preventing or stopping joint degeneration, rather than merely relieving the symptoms of the disease. This review summarises the current evidence relating to stem cell-derived EVs in joint injury and osteoarthritis, providing a concise discussion of their characteristics, advantages, therapeutic effects, limitations and outlook in this exciting new area.

Photoactivatable Prodrug of Doxazolidine Targeting Exosomes

Natural lipid nanocarriers, exosomes, carry cell-signaling materials such as DNA and RNA for intercellular communications. Exosomes derived from cancer cells contribute to the progression and metastasis of cancer cells by transferring oncogenic signaling molecules to neighboring and remote premetastatic sites. Therefore, applying the unique properties of exosomes for cancer therapy has been expected in science, medicine, and drug discovery fields. Herein, we report that an exosome-targeting prodrug system, designated MARCKS-ED-photodoxaz, could spatiotemporally control the activation of an exquisitely cytotoxic agent, doxazolidine (doxaz), with UV light. The MARCKS-ED peptide enters a cell by forming a complex with the exosomes in situ at its plasma membrane and in the media. MARCKS-ED-photodoxaz releases doxaz under near-UV irradiation to inhibit cell growth with low nanomolar IC₅₀ values. The MARCKS-ED-photodoxaz system targeting exosomes and utilizing photochemistry will potentially provide a new approach for the treatment of cancer, especially for highly progressive and invasive metastatic cancers.

Extracellular vesicles secreted by hypoxia pre-challenged mesenchymal stem cells promote non-small cell lung cancer cell growth and mobility as well as macrophage M2 polarization via miR-21-5p delivery

Objective

To investigate the lung cancer-promoting mechanism of mesenchymal stem cell-secreted extracellular vesicles (MSC-EV).

Methods

EV were isolated from culture media of human bone marrow-derived MSCs that were pre-challenged with or without hypoxia (referred to as H-EV and N-EV, respectively). After treatment with N-EV or H-EV, A549 and H23 cell proliferation, apoptosis, trans-well invasion and epithelial-to-mesenchymal transition (EMT) were examined. Polarization of human primary monocytes-derived macrophages with or without N-EV or H-EV induction were analyzed by flow cytometry and ELISA. PTEN, PDCD4 or RECK gene was overexpressed in A549 cells, while miR-21-5p was knocked down in MSCs, A549 or H23 lung cancer cells or primary monocytes by miR-21-5p inhibitor transfection. Protein level of PTEN, PDCD4, RECK, AKT or STAT3 as well as phosphorylation level of AKT or STAT3 protein were assayed by western blot. Tumorigenicity of A549 and H23 cells with or without MSC-EV co-injection was assayed on immunocompromised mice. The xenograft tumor were examined for cell proliferation, angiogenesis, apoptosis and intra-tumoral M1/M2 macrophage polarization.

Results

Comparing to N-EV, H-EV treatment significantly increased A549 and H23 cell proliferation, survival, invasiveness and EMT as well as macrophage M2 polarization. MiR-21-5p knocked down significantly abrogated the cancer-promoting and macrophage M2 polarizing effects of H-EV treatment. H-EV treatment downregulated PTEN, PDCD4 and RECK gene expression largely through miR-21-5p. Overexpressing PTEN, PDCD4 and RECK in A549 cells significantly reduced the miR-21-5p-mediated anti-apoptotic and pro-metastatic effect of H-EV, while overexpressing PTEN in monocytes significantly reduced macrophage M2 polarization after induction with the presence of H-EV. H-EV co-injection significantly increased tumor growth, cancer cell proliferation, intra-tumoral angiogenesis and M2 polarization of macrophages in vivo partially through miR-21-5p.

Conclusions

Increased miR-21-5p delivery by MSC-EV after hypoxia pre-challenge can promote lung cancer development by reducing apoptosis and promoting macrophage M2 polarization.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1027-0) contains supplementary material, which is available to authorized users.