Exosomal cargo-loading and synthetic exosome-mimics as potential therapeutic tools

Potential roles of extracellular vesicles in osteonecrosis of femoral head: A systematic review

Extracellular vesicles (EVs), have been utilised for the diagnosis and treatment of osteonecrosis of femoral head (ONFH). Hence, we aimed to review the available evidence on the potential roles of EVs in ONFH systematically. The PubMed, EMBASE, and Science Citation Index databases were searched exhaustively from inception to June 2020. All in vitro and in vivo studies on the use of EVs in ONFH diagnosis and treatment were included. The final analysis included 14 studies. These studies were categorised according to the cell source, target cell types, secreted product types, production method, storage, and study design. The animal model, together with the ONFH induction method, used in the in vivo studies was also considered. For in vivo studies, effects on cellular proliferation and apoptosis and bone and vascular tissues and biomarkers for ONFH diagnosis were assessed, whereas in the in vitro studies, effects on EVs internalization; proliferation, viability, and migration; osteogenic and adipogenic differentiation; apoptosis; and angiogenesis were evaluated. Both in vitro and in vivo studies showed promoting effects of EVs on proliferation, osteogenic differentiation, and angiogenesis and inhibitory effects on apoptosis and adipogenic differentiation in both glucocorticoid-induced and traumatic ONFH models. Additionally, EVs in blood showed diagnostic potential for ONFH. This systemic review provides a deeper understanding of the role of EVs, thereby facilitating the development of novel therapeutic strategies.

Adipose stem cell secretome markedly improves rodent heart and human induced pluripotent stem cell-derived cardiomyocyte recovery from cardioplegic transport solution exposure

Heart transplantation is a life-saving therapy for end-stage organ failure. Organ deterioration during transportation limits storage to 4 hours, limiting hearts available. Approaches ameliorating organ damage could increase the number of hearts acceptable for transplantation. Prior studies show that adipose-derived stem/stromal cell secretome (ASC-S) rescues tissues from postischemic damage in vivo. This study tested whether ASC-S preserved the function of mouse hearts and human induced pluripotent stem cell-derived cardiomyocytes (iCM) exposed to organ transportation and transplantation conditions. Hearts were subjected to cold University of Wisconsin (UW) cardioplegic solution ± ASC-S for 6 hours followed by analysis using the Langendorff technique. In parallel, the effects of ASC-S on the recovery of iCM from UW solution were examined when provided either during or after cold cardioplegia. Exposure of hearts and iCM to UW deteriorated contractile activity and caused cell apoptosis, worsening in iCM as a function of exposure time; these were ameliorated by augmenting with ASC-S. Silencing of superoxide dismutase 3 and catalase expression prior to secretome generation compromised the ASC-S cardiomyocyte-protective effects. In this study, a novel in vitro iCM model was developed to complement a rodent heart model in assessing efficacy of approaches to improve cardiac preservation. ASC-S displays strong cardioprotective activity on iCM either with or following cold cardioplegia. This effect is associated with ASC-S-mediated cellular clearance of reactive oxygen species. The effect of ASC-S on the temporal recovery of iCM function supports the possibility of lengthening heart storage by augmenting cardioplegic transport solution with ASC-S, expanding the pool of hearts for transplantation.

The Role(s) of Eicosanoids and Exosomes in Human Parturition

The roles that eicosanoids play during pregnancy and parturition are crucial to a successful outcome. A better understanding of the regulation of eicosanoid production and the roles played by the various end products during pregnancy and parturition has led to our view that accurate measurements of a panel of those end products has exciting potential as diagnostics and prognostics of preterm labor and delivery. Exosomes and their contents represent an exciting new area for research of movement of key biological factors circulating between tissues and organs akin to a parallel endocrine system but involving key intracellular mediators. Eicosanoids and enzymes regulating their biosynthesis and metabolism as well as regulatory microRNAs have been identified within exosomes. In this review, the regulation of eicosanoid production, abundance and actions during pregnancy will be explored. Additionally, the functional significance of placental exosomes will be discussed.

A Review of Biomimetic Nanoparticle Drug Delivery Systems Based on Cell Membranes

Cancers have always been an intractable problem because of recurrence and drug resistance. In the past few decades, nanoparticles have been explored intensely to diagnose, prevent and treat malignancy due to their good penetrability and better targeting. However, most nanocarriers have poor biodegradation and can be discharged out of the body quickly or cleared by immune cells while failing to obtain effective drug concentration at the specific sites. The emergence of biological membrane encapsulation technology relieves the fast clearance of antitumor drugs and reduces toxicity in vivo. This review will discuss the advantages and disadvantages of several blood cell membrane-coated nanoparticles and further introduce exosome-carried drugs to evidence the promising prospect of biomimetic nanoparticle drug delivery systems.

Exosome as a Natural Gene Delivery Vector for Cancer Treatment

Background:

Current gene therapy vectors such as viral, non-viral, and bacterial vectors, which are used for cancer treatment, but there are certain safety concerns and stability issues of these conventional vectors. Exosomes are the vesicles of size 40-100 nm secreted from multivesicular bodies into the extracellular environment by most of the cell types in-vivo and in-vitro. As a natural nanocarrier, exosomes are immunologically inert, biocompatible, and can cross biological barriers like the blood-brain barrier, intestinal barrier, and placental barrier.

Objective:

This review focusses on the role of exosome as a carrier to efficiently deliver a gene for cancer treatment and diagnosis. The methods for loading of nucleic acids onto the exosomes, advantages of exosomes as a smart intercellular shuttle for gene delivery and therapeutic applications as a gene delivery vector for siRNA, miRNA and Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) and also the limitations of exosomes as a gene carrier are all reviewed in this article.

Methods:

Mostly, electroporation and chemical transfection are used to prepare gene loaded exosomes.

Results:

Exosome-mediated delivery is highly promising and advantageous in comparison to the current delivery methods for systemic gene therapy. Targeted exosomes, loaded with therapeutic nucleic acids, can efficiently promote the reduction of tumor proliferation without any adverse effects.

Conclusion:

In the near future, exosomes can become an efficient gene carrier for delivery and a biomarker for the diagnosis and treatment of cancer.

The roles of exosomes in cancer drug resistance and its therapeutic application

Exosomes are a category of extracellular vesicles with a size ranging from 40 to 160 nm, which can be secreted by multiple cells in the tumor microenvironment. Exosomes serve as communicators in regulating biological functions and pathological processes, including drug response. Through transporting the cargo such as protein or nucleic acid, exosomes can modulate drug sensitivity via multiple mechanisms. Additionally, exosomes can be deployed as a delivery system to treat cancer due to their high-efficient loading capacity and tolerable toxicity. Recent studies have demonstrated the high efficacy of exosomes in cancer therapy. Herein, we conduct this review to summarize the mechanism of exosome-mediated drug resistance and the therapeutic potential of exosomes in cancer.

An Overview of Exosomes in Cancer Therapy: A Small Solution to a Big Problem

Exosomes are defined as a type of extracellular vesicle released when multivesicular bodies of the endocytic pathway fuse with the plasma membrane. They are characterized by their role in extracellular communication, partly due to their composition, and present the ability to recognize and interact with cells from the immune system, enabling an immune response. Their targeting capability and nanosized dimensions make them great candidates for cancer therapy. As chemotherapy is associated with cytotoxicity and multiple drug resistance, the use of exosomes targeting capabilities, able to deliver anticancer drugs specifically to cancer cells, is a great approach to overcome these disadvantages. The objective is to assess treatment efficiency in reducing tumor cells, as well as overall safety and response by cancer carriers. So far, results show exosomes as a promising therapeutic strategy in the fight against cancer. This review summarizes the characteristics and composition of exosomes, as well as explaining in detail the involved parties in the origin of exosomes. Furthermore, some considerations about exosome application in immunotherapy are addressed. The main isolation and loading methods are described to give an insight into how exosomes can be obtained and manipulated. Finally, some therapeutic applications of exosomes in cancer therapy are described.

Advances in Exosome-Based Drug Delivery and Tumor Targeting: From Tissue Distribution to Intracellular Fate

Exosomes or small extracellular vesicles are considered a new generation of bioinspired-nanoscale drug delivery system (DDS). Endogenous exosomes function as signalosomes since they convey signals via ligands or adhesion molecules located on the exosomal membrane, or packaged inside the exosome. Recently, exosome membrane modification, therapeutic payloads encapsulation, and modulation of in vivo disposition of exosomes have been extensively investigated, among which significant advances have been made to optimize exosome-mediated delivery to solid tumors. Exosomes, specifically tumor cell-derived exosomes, are presumed to have tumor-preferential delivery due to the homotypic features. However, quality attributes that dictate the tissue distribution, cell type-selective uptake, and intracellular payload release of the administered exosomes, as well as the spatiotemporal information regarding exosome fate in vivo, remain to be further investigated. This review summarizes recent advances in developing exosomes as drug delivery platforms with a focus on tumor targeting. The pharmacokinetic features of naive exosomes and factors influencing their intracellular fate are summarized. Recent strategies to improve tumor targeting of exosomes are also reviewed in the context of the biological features of tumor and tumor microenvironment (TME). Selected approaches to augment tumor tissue deposition of exosomes, as well as methods to enhance intracellular payload delivery, are summarized with emphasis on the underlying mechanisms (eg, passive or active targeting, endosomal escape, etc.). In conclusion, this review highlights recently reported tumor-targeting strategies of exosome-based drug delivery, and it's in the hope that multiple approaches might be employed in a synergistic combination in the development of exosome-based cancer therapy.

Recent Advancements in the Loading and Modification of Therapeutic Exosomes

Exosomes have a rapid development of bio-nanoparticles for drug delivery and confluent advances in next-generation diagnostics, monitoring the progression of several diseases, and accurate guidance for therapy. Based on their prominent stability, cargo-carriage properties, stable circulating capability, and favorable safety profile, exosomes have great potential to regulate cellular communication by carrying variable cargoes into specific site. However, the specific loading strategies and modification methods for engineered exosomes to enhance the targeting ability are unclear. The clinical application of exosomes is still limited. In this review, we discuss both original and modified exosomes for loading specific therapeutic molecules (proteins, nucleic acids, and small molecules) and the design strategies used to target specific cells. This review can be used as a reference for further loading and modification strategies as well as for the therapeutic applications of exosomes.

MiR-223-3p inhibits rTp17-induced inflammasome activation and pyroptosis by targeting NLRP3

The incidence of syphilis caused by Treponema pallidum subsp pallidum (T pallidum) infection is accompanied by inflammatory injuries of vascular endothelial cells. Studies have revealed that T pallidum infection could induce inflammasome activation and pyroptosis in macrophages. MicroRNA‐223‐3p (miR‐223‐3p) was reported to be a negative regulator in inflammatory diseases. The present study aimed to explore whether miR‐223‐3p regulates T pallidum‐induced inflammasome activation and pyroptosis in vascular endothelial cells, and determine the mechanisms which underlie this process. MiR‐223‐3p levels in syphilis and control samples were determined. The biological function of miR‐223‐3p in the NLRP3 inflammasome and pyroptosis was evaluated in T pallidum‐infected human umbilical vein endothelial cells (HUVECs). We observed a dramatic decrease in miR‐223‐3p levels in syphilis patients (n = 20) when compared to healthy controls (n = 20). Moreover, miR‐223‐3p showed a notable inhibitory effect on recombinant Tp17 (rTP17)‐induced caspase‐1 activation, resulting in decrease in IL‐1β production and pyroptosis, which was accompanied by the release of lactate dehydrogenase (LDH) in HUVECs. Additionally, the dual‐luciferase assay confirmed that NLRP3 is a direct target of miR‐223‐3p. Moreover, NLRP3 overexpression or knockdown largely blocked the effects of miR‐223‐3p on T pallidum‐induced inflammasome activation and pyroptosis in HUVECs. Most importantly, a notable negative correlation was observed between miR‐223‐3p and NLRP3, caspase‐1, and IL‐1β, respectively, in the serum of syphilis patients and healthy controls. Taken together, our results reveal that miR‐223‐3p targets NLRP3 to suppress inflammasome activation and pyroptosis in T pallidum‐infected endothelial cells, implying that miR‐223‐3p could be a potential target for syphilis patients.

Small Extracellular Vesicles from Lipopolysaccharide-Preconditioned Dental Follicle Cells Promote Periodontal Regeneration in an Inflammatory Microenvironment

Lipopolysaccharide (LPS)-induced inflammatory microenvironment can enhance the dental follicle cells (DFCs) proliferation, differentiation, and adhesion abilities beneficial to periodontal regeneration, which possibly attributes the success to exosomes according to recent studies. This study aimed to investigate the therapeutic efficacy and underlying mechanisms of LPS-preconditioned DFC-derived small extracellular vesicles (sEVs), which enriched exosomes for periodontal regeneration in an inflammatory microenvironment. LPS preconditioning could significantly increase the secretion of sEVs derived from DFCs. Both LPS-preconditioned dental follicle cell-derived sEV (L-D-sEV) and DFC-derived sEV (D-sEV) promoted the proliferation of periodontal ligament cells from periodontitis (p-PDLCs) with a dose-dependent and saturable manner and also enhanced the migration and differentiation of p-PDLCs. Furthermore, L-D-sEV showed a modest benefit than D-sEV to promote p-PDLCs differentiation. In vivo, an L-D-sEV-loaded hydrogel applied in the treatment of periodontitis was beneficial to repair lost alveolar bone in the early stage of treatment and to maintain the level of alveolar bone in the late stage of treatment in experimental periodontitis rats, which could partly decrease the expression of the RANKL/OPG ratio. In conclusion, L-D-sEV was beneficial to p-PDLCs forming an integrity periodontal tissue. The biological injectable L-D-sEV-loaded hydrogel could be used as a treatment method for experimental periodontitis in rats, promoting periodontal tissue regeneration and providing a new alternative cell therapy method for periodontal tissue regeneration.

Improvement, scaling-up, and downstream analysis of exosome production

Exosomes are the most researched extracellular vesicles. In many biological, physiological, and pathological studies, they have been identified as suitable candidates for treatment and diagnosis of diseases by acting as the carriers of both drugs and genes. Considerable success has been achieved regarding the use of exosomes for tissue regeneration, cancer diagnosis, and targeted drug/gene delivery to specific tissues. While major progress has been made in exosome extraction and purification, extraction of large quantities of exosomes is still a major challenge. This issue limits the scope of both exosome-based research and therapeutic development. In this review, we have aimed to summarize experimental studies focused at increasing the number of exosomes. Biotechnological studies aimed at identifying the pathways of exosome biogenesis to manipulate some genes in order to increase the production of exosomes. Generally, two major strategies are employed to increase the production of exosomes. First, oogenesis pathways are genetically manipulated to overexpress activator genes of exosome biogenesis and downregulate the genes involved in exosome recycling pathways. Second, manipulation of the cell culture medium, treatment with specific drugs, and limiting certain conditions can force the cell to produce more exosomes. In this study, we have reviewed and categorized these strategies. It is hoped that the information presented in this review will provide a better understanding for expanding biotechnological approaches in exosome-based therapeutic development.

Distinct miRNA Profile of Cellular and Extracellular Vesicles Released from Chicken Tracheal Cells Following Avian Influenza Virus Infection

Innate responses provide the first line of defense against viral infections, including the influenza virus at mucosal surfaces. Communication and interaction between different host cells at the early stage of viral infections determine the quality and magnitude of immune responses against the invading virus. The release of membrane-encapsulated extracellular vesicles (EVs), from host cells, is defined as a refined system of cell-to-cell communication. EVs contain a diverse array of biomolecules, including microRNAs (miRNAs). We hypothesized that the activation of the tracheal cells with different stimuli impacts the cellular and EV miRNA profiles. Chicken tracheal rings were stimulated with polyI:C and LPS from Escherichia coli 026:B6 or infected with low pathogenic avian influenza virus H4N6. Subsequently, miRNAs were isolated from chicken tracheal cells or from EVs released from chicken tracheal cells. Differentially expressed (DE) miRNAs were identified in treated groups when compared to the control group. Our results demonstrated that there were 67 up-regulated miRNAs, 157 down-regulated miRNAs across all cellular and EV samples. In the next step, several genes or pathways targeted by DE miRNAs were predicted. Overall, this study presented a global miRNA expression profile in chicken tracheas in response to avian influenza viruses (AIV) and toll-like receptor (TLR) ligands. The results presented predicted the possible roles of some DE miRNAs in the induction of antiviral responses. The DE candidate miRNAs, including miR-146a, miR-146b, miR-205a, miR-205b and miR-449, can be investigated further for functional validation studies and to be used as novel prophylactic and therapeutic targets in tailoring or enhancing antiviral responses against AIV.

Biomimetic nanovesicle design for cardiac tissue repair

Cardiovascular disease is a major cause of mortality and morbidity worldwide. Exosome therapies are promising for cardiac repair. Exosomes transfer cargo between cells, have high uptake by native cells and are ideal natural carriers for proteins and nucleic acids. Despite their proreparative potential, exosome production is dependent on parent cell state with typically low yields and cargo variability. Therefore, there is potential value in engineering exosomes to maximize their benefits by delivering customized, potent cargo for cardiovascular disease. Here, we outline several methods of exosome engineering focusing on three important aspects: optimizing cargo, homing to target tissue and minimizing clearance. Finally, we put these methods in context of the cardiac field and discuss the future potential of vesicle design.

Exosomics

Extracellular vesicles have been the focus of a large number of studies in the past five years. Exosomes, a subgroup of extracellular vesicles, are of particularly high interest because they partake in a wide number of biological pathways. Produced by a variety of cells, exosomes have an important role in both physiological and pathological conditions. Exosome cargo heavily defines the vesicles’ unique characteristics, and the cargo with the most intriguing prospects in its’ biomedical applications is the non-coding RNAs. Non-coding RNAs, and specifically microRNAs are implicated in the regulation of many biological processes and have been associated with numerous diseases. Exosomes containing such important cargo can be used as biomarkers, therapeutic biomaterials, or even drug carriers. The potential media use of exosomes seems promising. However, some obstacles should be overcome before their clinical application. Synthetic exosome-like biomolecules may be a solution, but their production is still in their beginning stages. This review provides concise information regarding the current trends in exosome studies.

Efficient Doxorubicin Loading to Isolated Dexosomes of Immature JAWSII Cells: Formulated and Characterized as the Bionanomaterial

Immature dendritic cells (IDc), 'dexosomes', are promising natural nanomaterials for cancer diagnose and therapy. Dexosomes were isolated purely from small-scale-up production by using t25-cell-culture flasks. Total RNA was measured as 1.43 ± 0.33 ng/10⁶ cell. Despite the fact that they possessed a surface that is highly abundant in protein, this did not become a significant effect on the DOX loading amount. Ultrasonication was used for doxorubicin (DOX) loading into the IDc dexosomes. In accordance with the literature, three candidate DOX formulations were designed as IC50 values; dExoIII, 1.8 µg/mL, dExoII, 1.2 µg/mL, and dExoI, 0.6 µg/mL, respectively. Formulations were evaluated by MTT test against highly metastatic A549 (CCL-185; ATTC) cell line. Confocal images of unloaded (naïve) were obtained by CellMask^TM membrane staining before DOX loading. Although, dexosome membranes were highly durable subsequent to ultrasonication, it was observed that dexosomes could not be stable above 70 °C during the SEM-image analyses. dExoIII displayed sustained release profile. It was found that dynamic light scattering (DLS) and nanoparticle tracking analysis (NTA) results were in good agreement with each other. Zeta potentials of loaded dexosomes have approximately between -15 to -20 mV; and, their sizes are 150 nm even after ultrasonication. IDcJAWSII dexosomes can be able to be utilized as the "BioNanoMaterial" after DOX loading via ultrasonication technique.

Exosome: a significant nano-scale drug delivery carrier

In recent years, due to the limitations of the nature of therapeutic agents, many synthetic nano-delivery systems have emerged to enhance the efficacy of drugs. Extracellular vesicles are currently a class of natural nano-scale drug carriers released by cells. As a tiny vesicle with a lipid bilayer membrane that can be secreted by most cells in the body, exosomes carry and transmit important signal molecules, Therefore, they have been a research hotspot in biomedicine and biomaterials due to their size advantages and huge potential in drug therapy. Many people are optimistic about the clinical application prospects of exosomes and are actively exploring the broad functions of exosomes and developing exosome therapeutic agents to make positive contributions to human health. In this review, we provide basic knowledge and focus on summarizing the advantages of exosomes as drug carriers, methods of loading drugs, targeting strategies, in vivo and in vitro tracing methods, and some of the latest developments in exosomes as drug carriers. In particular, the review provides an outlook for this field.

The Role of MicroRNAs in Repair Processes in Multiple Sclerosis

Multiple sclerosis (MS) is an autoimmune disorder characterised by demyelination of central nervous system neurons with subsequent damage, cell death and disability. While mechanisms exist in the CNS to repair this damage, they are disrupted in MS and currently there are no treatments to address this deficit. In recent years, increasing attention has been paid to the influence of the small, non-coding RNA molecules, microRNAs (miRNAs), in autoimmune disorders, including MS. In this review, we examine the role of miRNAs in remyelination in the different cell types that contribute to MS. We focus on key miRNAs that have a central role in mediating the repair process, along with several more that play either secondary or inhibitory roles in one or more aspects. Finally, we consider the current state of miRNAs as therapeutic targets in MS, acknowledging current challenges and potential strategies to overcome them in developing effective novel therapeutics to enhance repair mechanisms in MS.

Extracellular Vesicles as Delivery Vehicles of Specific Cellular Cargo

Extracellular vesicles (EVs) mediate cell-to-cell communication via the transfer of biomolecules locally and systemically between organs. It has been elucidated that the specific EV cargo load is fundamental for cellular response upon EV delivery. Therefore, revealing the specific molecular machinery that functionally regulates the precise EV cargo intracellularly is of importance in understanding the role of EVs in physiology and pathophysiology and conveying therapeutic use. The purpose of this review is to summarize recent findings on the general rules, as well as specific modulator motifs governing EV cargo loading. Finally, we address available information on potential therapeutic strategies to alter cargo loading.

Exosome biogenesis, secretion and function of exosomal miRNAs in skeletal muscle myogenesis

Exosomes are membrane-bound extracellular vesicles that are produced in the endosomal compartment of most mammalian cell types and then released. Exosomes are effective carriers for the intercellular material transfer of material that can influence a series of physiological and pathological processes in recipient cells. Among loaded cargoes, non-coding RNAs (ncRNAs) vary for the exosome-producing cell and its homeostatic state, and characterization of the biogenesis and secretion of exosomal ncRNAs and the functions of these ncRNAs in skeletal muscle myogenesis remain preliminary. In this review, we will describe what is currently known of exosome biogenesis, release and uptake of exosomal ncRNAs, as well as the varied functions of exosomal miRNAs in skeletal muscle myogenesis.

MiRNA Profiling in Plasma Neural-Derived Small Extracellular Vesicles from Patients with Alzheimer's Disease

Small extracellular vesicles (EVs) are able to pass from the central nervous system (CNS) into peripheral blood and contain molecule markers of their parental origin. The aim of our study was to isolate and characterize total and neural-derived small EVs (NDEVs) and their micro RNA (miRNA) cargo in Alzheimer's disease (AD) patients. Small NDEVs were isolated from plasma in a population consisting of 40 AD patients and 40 healthy subjects (CTRLs) using high throughput Advanced TaqMan miRNA OpenArrays^®, which enables the simultaneous determination of 754 miRNAs. MiR-23a-3p, miR-223-3p, miR-100-3p and miR-190-5p showed a significant dysregulation in small NDEVs from AD patients as compared with controls (1.16 ± 0.49 versus 7.54 ± 2.5, p = 0.026; 9.32 ± 2.27 versus 0.66 ± 0.18, p <0.0001; 0.069 ± 0.01 versus 0.5 ± 0.1, p < 0.0001 and 2.9 ± 1.2 versus 1.93 ± 0.9, p < 0.05, respectively). A further validation analysis confirmed that miR-23a-3p, miR-223-3p and miR-190a-5p levels in small NDEVs from AD patients were significantly upregulated as compared with controls (p = 0.008; p = 0.016; p = 0.003, respectively) whereas miR-100-3p levels were significantly downregulated (p = 0.008). This is the first study that carries out the comparison between total plasma small EV population and NDEVs, demonstrating the presence of a specific AD NDEV miRNA signature.

Harnessing helminth-driven immunoregulation in the search for novel therapeutic modalities

Parasitic helminths have coevolved with humans over millennia, intricately refining and developing an array of mechanisms to suppress or skew the host’s immune system, thereby promoting their long-term survival. Some helminths, such as hookworms, cause little to no overt pathology when present in modest numbers and may even confer benefits to their human host. To exploit this evolutionary phenomenon, clinical trials of human helminth infection have been established and assessed for safety and efficacy for a range of immune dysfunction diseases and have yielded mixed outcomes. Studies of live helminth therapy in mice and larger animals have convincingly shown that helminths and their excretory/secretory products possess anti-inflammatory drug-like properties and represent an untapped pharmacopeia. These anti-inflammatory moieties include extracellular vesicles, proteins, glycans, post-translational modifications, and various metabolites. Although the concept of helminth-inspired therapies holds promise, it also presents a challenge to the drug development community, which is generally unfamiliar with foreign biologics that do not behave like antibodies. Identification and characterization of helminth molecules and vesicles and the molecular pathways they target in the host present a unique opportunity to develop tailored drugs inspired by nature that are efficacious, safe, and have minimal immunogenicity. Even so, much work remains to mine and assess this out-of-the-box therapeutic modality. Industry-based organizations need to consider long-haul investments aimed at unraveling and exploiting unique and differentiated mechanisms of action as opposed to toe-dipping entries with an eye on rapid and profitable turnarounds.

The Progress in Diagnosis and Treatment of Exosomes and MicroRNAs on Epileptic Comorbidity Depression

The occurrence of epilepsy can increase the incidence of depression, and the risk of epilepsy in the patients with depression is also high, both of which have an adverse effect on the life and the psychology of the patient, which is not conducive to the prognosis of the patients with epilepsy. With lucubrating the function of exosomes and microRNAs, some scholars found that the exosomes and its microRNAs have development prospect in the diagnosis and treatment of the disease. MicroRNAs are involved in the regulation of seizures and depression, as biomarkers, that can significantly improve the management of epileptic patients and play a preventive role in the occurrence of epilepsy and epilepsy depressive disorder. Moreover, due to its regulation to genes, appropriate application of microRNAs may have therapeutic effect on epilepsy and depression with the characteristics of long distance transmission and stability of exosomes, to a certain extent. This provides a great convenience for the diagnosis and treatment of epileptic comorbidity depression.

Novel Applications of Mesenchymal Stem Cell-derived Exosomes for Myocardial Infarction Therapeutics

Cardiovascular diseases (CVDs) are the leading cause of mortality and morbidity globally, representing approximately a third of all deaths every year. The greater part of these cases is represented by myocardial infarction (MI), or heart attack as it is better known, which occurs when declining blood flow to the heart causes injury to cardiac tissue. Mesenchymal stem cells (MSCs) are multipotent stem cells that represent a promising vector for cell therapies that aim to treat MI due to their potent regenerative effects. However, it remains unclear the extent to which MSC-based therapies are able to induce regeneration in the heart and even less clear the degree to which clinical outcomes could be improved. Exosomes, which are small extracellular vesicles (EVs) known to have implications in intracellular communication, derived from MSCs (MSC-Exos), have recently emerged as a novel cell-free vector that is capable of conferring cardio-protection and regeneration in target cardiac cells. In this review, we assess the current state of research of MSC-Exos in the context of MI. In particular, we place emphasis on the mechanisms of action by which MSC-Exos accomplish their therapeutic effects, along with commentary on the current difficulties faced with exosome research and the ongoing clinical applications of stem-cell derived exosomes in different medical contexts.

Predicting the presence of breast cancer using circulating small RNAs, including those in the extracellular vesicles

Emerging evidence indicates that small RNAs, including microRNAs (miRNAs) and their isoforms (isomiRs), and transfer RNA fragments (tRFs), are differently expressed in breast cancer (BC) and can be detected in blood circulation. Circulating small RNAs and small RNAs in extracellular vesicles (EVs) have emerged as ideal markers in small RNA‐based applications for cancer detection. In this study, we first undertook small RNA sequencing to assess the expression of circulating small RNAs in the serum of BC patients and cancer‐free individuals (controls). Expression of 3 small RNAs, namely isomiR of miR‐21‐5p (3′ addition C), miR‐23a‐3p and tRF‐Lys (TTT), was significantly higher in BC samples and was validated by small RNA sequencing in an independent cohort. Our constructed model using 3 small RNAs showed high diagnostic accuracy with an area under the receiver operating characteristic curve of 0.92 and discriminated early‐stage BCs at stage 0 from control. To test the possibility that these small RNAs are released from cancer cells, we next examined EVs from the serum of BC patients and controls. Two of the 3 candidate small RNAs were identified, and shown to be abundant in EVs of BC patients. Interestingly, these 2 small RNAs are also more abundantly detected in culture media of breast cancer cell lines (MCF‐7 and MDA‐MB‐231). The same tendency in selective elevation seen in total serum, serum EV, and EV derived from cell culture media could indicate the efficiency of this model using total serum of patients. These findings indicate that small RNAs serve as significant biomarkers for BC detection.

Electron Microscopy-Based Comparison and Investigation of the Morphology of Exosomes Derived from Hepatocellular Carcinoma Cells Isolated at Different Centrifugal Speeds

Exosomes derived from hepatocellular carcinoma (HCC) cells are nanovesicles and are involved in the occurrence and development of HCC, they also serve as important carriers and drug targets of nanodrug delivery systems. The external shape and internal structure of exosomes are important indexes of identification, and isolated intact morphology is crucial to biological function integrity. However, given their susceptibility to various influencing factors, the external shape and internal structure of exosomes derived from HCC cells remain incompletely studied. In this study, exosomes purified from HCC cells were isolated at different centrifugation speeds and examined via multiple electron microscopy (EM) techniques. The results demonstrate that exosomes possess a nearly spherical shape and bilipid membranous vesicle with a concave cavity structure containing electron-dense and coated vesicles, suggesting the possible existence of subpopulations of exosomes with specific functions. The exosomes isolated at ultracentrifugation (UC) speed (≥110,000×g) presented irregular and diverse external morphologies, indicating the effect on the integrity of the exosomes. Transforming growth factor signaling bioactive substances (TGF-β1, S100A8, and S100A9) can be found in exosomes by performing Western blotting, showing that the internal content is associated with metastasis of HCC. These findings show that EMelectron microscopy and UC speed can affect exosome characteristics, including external shape, internal structure, and content of bioactive substances. The electron-dense and coated vesicles that had been discovered in exosomes might become new additional morphological features, which could help to improve the interpretation of experimental results and widen our understanding of exosome morphology.

Hypoxia in tumor microenvironment regulates exosome biogenesis: Molecular mechanisms and translational opportunities

Hypoxia is a key feature of solid tumors, associated with disease aggressiveness and poor outcome. Besides undergoing broad intracellular molecular and metabolic adaptations, hypoxic tumor cells extensively communicate with their microenvironment to concoct conditions favorable for their survival, growth and metastatic spread. This mode of communication is through diverse secretory factors including exosomes (extracellular vesicles of endosomal origin and ~30-150 nm in diameter) which could carry package of molecular information including proteins, nucleic acids, lipids, and metabolites wrapped in lipid bilayer. Numerous studies have concluded that hypoxia promotes exosomes secretion by cancer cells. Moreover, exosomal cargo is considerably altered under hypoxia, dictating tumor cells communication with its local and distant microenvironment. In this review, we have summarized the effects of hypoxia on exosomes (Exo^Hypoxic) secretion and cargo sorting (miRNAs, proteins, lipids and metabolites) as well as their biological effects in local and distant microenvironment. We have described the key molecular mechanisms (e.g. HIF-1α, ceramides, RAB GTPases, tetraspanins, oxidative stress etc) involved in the production of Exo^Hypoxic. Lastly, we have highlighted the potential usefulness of Exo^Hypoxic in cancer prognosis as well as therapeutic opportunities in targeting Exo^Hypoxic.

99mTc-radiolabeled HER2 targeted exosome for tumor imaging

Exosomes represent unique features including nontoxicity, non-immunogenicity, biodegradability, and targeting ability that make them suitable candidates for clinical applications. Therefore, in this study, ^99mTc-radiolabel HER2 targeted exosomes (^99mTc-exosomes) were provided for tumor imaging. These exomes are obtained from genetically engineered cells and possessed DARPin G3 as a ligand for HER2 receptors. These exosomes were radiolabeled using fac-[^99mTc(CO)₃(H₂O)₃]⁺ synthon. The quality control showed high radiochemical purity (RCP) for ^99mTc-exosomes (>96%). ^99mTc-exosomes displayed a higher affinity toward SKOV-3 cells (higher HER2 expression) in comparison with MCF-7, HT29, U87-MG, A549 cell lines at different levels of HER2 expression. Trastuzumab (an antibody with a high affinity toward HER2) inhibited the binding of ^99mTc-exosomes to SKOV-3 cells up to 40%. Biodistribution study in SKOV-3 tumor bearing nude mice confirmed the ability of ^99mTc-exosomes for accumulation in the tumor. ^99mTc-exosomes can visualize tumor in SKOV-3 tumor-bearing nude mouse. The blockage of HER2 receptors using trastuzumab (excessive amount) suggests the ^99mTc-exosomes binding to the receptors and reduced the accumulation of ^99mTc-exosomes in the tumor site. This suggest that ^99mTc-exosomes interact with HER2 receptors and act through specific targeting.

Exosomal Nrf2: From anti-oxidant and anti-inflammation response to wound healing and tissue regeneration in aged-related diseases

Accumulation of oxidative stress in cells is an essential feature of cellular senescence and aging. This phenomenon is involved in different age-related diseases through dysregulation of homeostasis and impairing repair and regeneration (wound healing) capacity, which can suppress antioxidant responses such as the activity of antioxidant enzymes and damaged protein clearance system. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcription factor which regulates basal and inducible expression pattern of specific genes (antioxidants and detoxifications) through antioxidant element response (ARE) sites in the stress condition, specifically in chronic and age-related stresses. Nrf2 maintains cellular redox hemostasis and promotes rejuvenation. Exosomes are nanoscale vesicles that are released by various cells to actively regulate the complex cellular signaling networks. Exosomal-Nrf2 and exosomal-Nrf2-mediated products can modulate oxidative hemostasis in target cells to induce tissue repairing with therapeutic proposes, and regeneration capability. In this study, we summarized the role of exosomal-Nrf2 in different age-related diseases, including diabetic foot ulcers, atherosclerosis, chronic heart failure, reproductive cell failures, and neurodegenerative diseases. In addition, we briefly explained the crosstalk between plant exosomes and mammalian cell metabolism in the benefit of cellular stress suppression.

Hepatocellular carcinoma-derived exosomes in organotropic metastasis, recurrence and early diagnosis application

Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer, despite improvements in the clinical trial and diagnosis, HCC still remains high mortality due to the 70% recurrence and lung metastasis after surgical resection. Exosomes are small membrane vesicles, which are shuttled from donor cells to recipient cells, contributing to the recruitment and reprogramming of constituents via an autocrine or paracrine fashion. HCC derived exosomes could redirect metastasis of tumor cells which lack the capacity to metastasize to a specific organ via generating pre-metastatic niche. These findings emphasize a practical and potentially feasible role of exosomes in the treatment of patients with HCC, both as a target and a vehicle for drug design. We herein summarize recent findings that implicate oncogenes and non-canonical signaling of HCC exosomes, as well as the impact of exosomal bioactive molecules in high recurrence induced by organ-specific metastasis. The aim of review is to illustrate the underlying mechanism of exosomes in tumor metastasis, immune evasion, and the potential application of prognostic biomarker in HCC process.

Exosomes as a storehouse of tissue remodeling proteases and mediators of cancer progression

Rapidly increasing scientific reports of exosomes and their biological effects have improved our understanding of their cellular sources and their cell-to-cell communication. These nano-sized vesicles act as potent carriers of regulatory bio-macromolecules and can induce regulatory functions by delivering them from its source to recipient cells. The details of their communication network are less understood. Recent studies have shown that apart from delivering its cargo to the cells, it can directly act on extracellular matrix (ECM) proteins and growth factors and can induce various remodeling events. More importantly, exosomes carry many surface-bound proteases, which can cleave different ECM proteins and carbohydrates and can shed cell surface receptors. These local extracellular events can modulate signaling cascades, which consequently influences the whole tissue and organ. This review aims to highlight the critical roles of exosomal proteases and their mechanistic insights within the cellular and extracellular environment.

Curcumin stimulates exosome/microvesicle release in an in vitro model of intracellular lipid accumulation by increasing ceramide synthesis

Curcumin, a hydrophobic polyphenol found in the rhizome of Curcuma longa, has been shown to reduce intracellular lipid accumulation in mouse models of lysosomal storage diseases such as Niemann-Pick type C. Exosomes are small extracellular vesicles secreted by cells in response to changes in intracellular ceramide composition. Curcumin can induce exosome/microvesicle release in cellular models of lipid deposition; however, the mechanism by which curcumin stimulates this release is unknown. In a model of lipid trafficking impairment in C6 glia cells, we show that curcumin stimulated ceramide synthesis by increasing the intracellular concentration of ceramide-dihydroceramide. Ceramide overload increased exosome/microvesicle secretion 10-fold, thereby reducing the concentration of lipids in the endolysosomal compartment. These effects were blocked by inhibitors of serine palmitoyltransferase (myriocin) and ceramide synthase (fumonisin B1). It is concluded that the decrease in intracellular lipid deposition induced by curcumin is mediated by increased ceramide synthesis and exosome/microvesicle release. This action may represent an additional health benefit of curcumin.

Mircrining the injured heart with stem cell-derived exosomes: an emerging strategy of cell-free therapy

Bone marrow-derived mesenchymal stem cells (MSCs) have successfully progressed to phase III clinical trials successive to an intensive in vitro and pre-clinical assessment in experimental animal models of ischemic myocardial injury. With scanty evidence regarding their cardiogenic differentiation in the recipient patients' hearts post-engraftment, paracrine secretion of bioactive molecules is being accepted as the most probable underlying mechanism to interpret the beneficial effects of cell therapy. Secretion of small non-coding microRNA (miR) constitutes an integral part of the paracrine activity of stem cells, and there is emerging interest in miRs' delivery to the heart as part of cell-free therapy to exploit their integral role in various cellular processes. MSCs also release membrane vesicles of diverse sizes loaded with a wide array of miRs as part of their paracrine secretions primarily for intercellular communication and to shuttle genetic material. Exosomes can also be loaded with miRs of interest for delivery to the organs of interest including the heart, and hence, exosome-based cell-free therapy is being assessed for cell-free therapy as an alternative to cell-based therapy. This review of literature provides an update on cell-free therapy with primary focus on exosomes derived from BM-derived MSCs for myocardial repair.

Clinical Potential of Extracellular Vesicles in Type 2 Diabetes

Type 2 diabetes (T2D) is a major public health disease which is increased in incidence and prevalence throughout the whole world. Insulin resistance (IR) in peripheral tissues and insufficient pancreatic β-cell mass and function have been recognized as primary mechanisms in the pathogenesis of T2D, while recently, systemic chronic inflammation resulting from obesity and a sedentary lifestyle has also gained considerable attention in T2D progression. Nowadays, accumulating evidence has revealed extracellular vesicles (EVs) as critical mediators promoting the pathogenesis of T2D. They can also be used in the diagnosis and treatment of T2D and its complications. In this review, we briefly introduce the basic concepts of EVs and their potential roles in the pathogenesis of T2D. Then, we discuss their diagnostic and therapeutic potentials in T2D and its complications, hoping to open new prospects for the management of T2D.

Cytochalasin-B-Inducible Nanovesicle Mimics of Natural Extracellular Vesicles That Are Capable of Nucleic Acid Transfer

Extracellular vesicles provide cell-to-cell communication and have great potential for use as therapeutic carriers. This study was aimed at the development of an extracellular vesicle-based system for nucleic acid delivery. Three types of nanovesicles were assayed as oligonucleotide carriers: mesenchymal stem cell-derived extracellular vesicles and mimics prepared either by cell treatment with cytochalasin B or by vesicle generation from plasma membrane. Nanovesicles were loaded with a DNA oligonucleotide by freezing/thawing, sonication, or permeabilization with saponin. Oligonucleotide delivery was assayed using HEK293 cells. Extracellular vesicles and mimics were characterized by a similar oligonucleotide loading level but different efficiency of oligonucleotide delivery. Cytochalasin-B-inducible nanovesicles exhibited the highest level of oligonucleotide accumulation in HEK293 cells and a loading capacity of 0.44 ± 0.05 pmol/µg. The loaded oligonucleotide was mostly protected from nuclease action.

Long noncoding RNAs and exosomal lncRNAs: classification, and mechanisms in breast cancer metastasis and drug resistance

Breast cancer is the most common cancer, and the second cause of cancer-related deaths (after lung cancer) among women. Developing tumor metastasis and invasion is the most important cause of death in breast cancer patients. Several key factors participate in breast cancer metastasis including long noncoding RNAs (lncRNAs). lncRNAs are a category of cellular RNAs that are longer than 200 nucleotides in length. Accumulating evidence suggests that lncRNAs have the potential to be promising diagnostic, prognostic biomarkers and therapeutic targets in breast cancer. Understanding the role of lncRNAs and their mechanisms of functions might help to further discovery of breast cancer biological characteristics. In this review, we discuss physiological functions, epigenetic regulation, transcriptional regulation of lncRNAs, and their important role in tumor progression and metastasis. Some lncRNAs function as oncogenes and some function as tumor suppressors. Interestingly, recent reports depict that hypomethylation of promoters of lncRNAs play a pivotal role in cancer progression, suggesting the importance of epigenetic regulation. Furthermore, we discuss the role of lncRNAs in exosomes and their function in drug resistance, and therapeutic importance of exosomal lncRNAs in cancer biology. In summary, lncRNAs have a great potential to consider them as novel prognostic biomarkers as well as new therapeutic targets in breast cancer.

MiR-216a-5p-containing exosomes suppress rTp17-induced inflammatory response by targeting TLR4

Syphilis caused by Treponema pallidum (T. pallidum) infection is accompanied by inflammatory injury of tissue, and has a worldwide distribution and increasing incidence over the past decade. Tp17 has been reported to be a strong membrane immunogen, and was initially observed to play a role in inflammation during syphilis, reacting intensely with human syphilitic sera. We therefore used recombinant Tp17 (rTp17) as a stimulator in our study. Increasing evidence has demonstrated that microRNA (miRNA)-containing exosomes have emerged as a potential effective therapeutic target for many diseases. However, the biological functions and molecular mechanisms of miR-216a-5p in syphilis pathogenesis remain unknown. Our study first identified dramatically decreased miR-216a-5p in plasma of syphilis patients compared with the healthy control, which was negatively correlated with the expression of inflammatory cytokines, including IL-1β, IL-6, and TNF-α. Moreover, endothelial cells treated with miR-216a-5p-containing exosomes significantly attenuated the rTp17-induced inflammatory response. More importantly, we identified that miR-216a-5p could bind to the 3′-untranslated region (UTR) of Toll-like receptor (TLR) 4 (TLR4), and overexpression of TLR4 largely rescued the miR-216a-5p-mediated suppression of rTp17-induced inflammatory cytokine production and the TLR4-MYD88 signaling pathway. Thus, our results reveal a novel role of miR-216a-5p-containing exosomes in endothelial cells, implying a potential therapeutic target for inflammation in syphilis patients.

Cell-Derived Vesicles for in Vitro and in Vivo Targeted Therapeutic Delivery

Efficient delivery of therapeutics across the cell membrane to the interior of the cell remains a challenge both in vitro and in vivo. Here, we demonstrate that vesicles derived from cellular membranes can be efficiently loaded with cargo that can then be delivered to the interior of the cell. These vesicles demonstrated cell-targeting specificity as well as the ability to deliver a wide range of different cargos. We utilized this approach to deliver both lipophilic and hydrophilic cargos including therapeutics and DNA in vitro. We further demonstrated in vivo targeting and delivery using fluorescently labeled vesicles to target tumor xenografts in an animal. Cell-derived vesicles can be generated in high yields and are easily loaded with a variety of cargos. The ability of these vesicles to specifically target the same cell type from which they originated provides an efficient means of delivering cargo, such as therapeutics, both in vitro and in vivo.

Evaluation of circulating small extracellular vesicles derived miRNAs as biomarkers of early colon cancer: a comparison with plasma total miRNAs

Early diagnosis of colon cancer (CC) is clinically important, as it can significantly improve patients’ survival rate and quality of life. Although the potential role for small extracellular vesicles (sEVs) in early detection of many diseases has been repeatedly mentioned, systematic screening of plasma sEVs derived early CC specific biomarkers has not yet been reported. In this work, plasma sEVs enriched fractions were derived from 15 early-stage (TisN0M0) CC patients and 10 normal controls (NC). RNA sequencing identified a total number of 95 sEVs enriched fraction derived miRNAs with differential expression between CC and NC, most of which (60/95) was in well accordance with tissue results in the Cancer Genome Atlas (TCGA) dataset. Among those miRNAs, we selected let-7b-3p, miR-139-3p, miR-145-3p, and miR-150-3p for further validation in an independent cohort consisting of 134 participants (58 CC and 76 NC). In the validation cohort, the AUC of 4 individual miRNAs ranged from 0.680 to 0.792. A logistic model combining two miRNAs (i.e. let-7b-3p and miR-145-3p) achieved an AUC of 0.901. Adding the 3rd miRNA into this model can further increase the AUC to 0.927. Side by side comparison revealed that sEVs miRNA profile outperformed cell-free plasma miRNA in the diagnosis of early CC. In conclusion, we suggested that circulating sEVs enriched fractions have a distinct miRNA profile in CC patients, and sEVs derived miRNA could be used as a promising biomarker to detect CC at an early stage.

Exosome-mimetic nanoplatforms for targeted cancer drug delivery

Background

Lack of effective tumor-specific delivery systems remains an unmet clinical challenge for successful translation of innovative therapies, such as, therapeutic oligonucleotides. In the past decade, exosomes have been suggested to be ideal drug delivery systems with application in a broad range of pathologies including cancer, due to their organotropic properties. Tumor-derived exosomes, having tumor-homing properties, can efficiently reach cancer cells and therefore behave as carriers for improved drug delivery to the primary tumor and metastases. However, due to their complex composition, and still undefined biological functions, safety concerns arise hampering their translation to the clinics.

Results

We propose here the development of exosome-mimetic nanosystems (EMNs) that simulate natural tumor-derived exosomes with respect to their structure and functionality, but with a controlled composition, for the targeted delivery of therapeutic oligonucleotides to lung adenocarcinoma cells (microRNA-145 mimics). Making use of the well-known liposome technology, EMNs can be engineered, loaded with the therapeutic compounds, and tailored with specific proteins (integrin α6β4) providing them organotropic properties. EMNs show great similarities to natural exosomes with respect to their physicochemical properties, drug loading capacity, and ability to interact with the cancer target cells in vitro and in vivo, but are easier to manufacture, can be produced at high yields, and are safer by definition.

Conclusions

We have designed a multifunctional nanoplatform mimicking exosomes, EMNs, and proved their potential to reach cancer cells with a similar efficient that tumor-derived exosomes but providing important advantages in terms of production methodology and regulations. Additionally, EMNs are highly versatile systems that can be tunable for a broader range of applications.

Electronic supplementary material

The online version of this article (10.1186/s12951-019-0517-8) contains supplementary material, which is available to authorized users.

Ratiometric theranostic nanoprobe for pH imaging-guided photodynamic therapy

An abnormal pH microenvironment results from the development of tumors, and also affects the therapeutic efficiency of anti-tumor drugs. In this work, a Förster resonance energy transfer (FRET)-based theranostic fluorescent nanoprobe was constructed for simultaneous ratiometric pH sensing and tumor-targeted photodynamic therapy. Based on the FRET process between rhodamine B and protoporphyrin IX (PpIX), the fabricated nanoprobe exhibited excellent pH responsiveness in both solutions and live cells with the ratiometric fluorescence changes. Moreover, this ratiometric pH fluorescent nanoprobe also possessed the capability for pH-responsive singlet oxygen (1O2) generation under light irradiation, guiding robust photodynamic therapy in a pH-dependent manner. Benefiting from the enhanced permeability and retention (EPR) effect, the nanoprobe could significantly inhibit tumor growth and metastasis via targeted photodynamic therapy in vivo. This work presents a novel paradigm for precise tumor theranostics by ratiometric pH fluorescence imaging-guided photodynamic therapy.

Mesenchymal Stem Cell-Derived Extracellular Vesicles as Therapeutics and as a Drug Delivery Platform

Mesenchymal stem cells (MSCs) are one of the most easily accessible stem cells that can be obtained from various human tissues. They have raised considerable interests for their potential applications in tissue repair, anti‐cancer therapy, and inflammation suppression. Stem cell‐based therapy was first used to treat muscular dystrophies and has been studied intensively for its efficacy in various disease models, including myocardial infarction, kidney injuries, liver injuries, and cancers. In this review, we summarized the potential mechanisms underlying MSC‐derived EVs therapy as a drug delivery platform. Additionally, based on currently published data, we predicted a potential therapeutic role of cargo proteins shuttled by EVs from MSCs. These data may support the therapeutic strategy of using the MSC‐derived EVs to accelerate this strategy from bench to bedside. stem cells translational medicine2019;8:880&886

Design strategies and application progress of therapeutic exosomes

Exosomes have great potential to be drug delivery vehicles due to their natural material transportation properties, intrinsic long-term circulatory capability, and excellent biocompatibility, which are suitable for delivering a variety of chemicals, proteins, nucleic acids, and gene therapeutic agents. However, an effective method of loading specific protein agents into exosomes for absorption by target cells is still lacking. The application potential of exosome is still limited. In this review, we discussed the methods for loading specific treating molecules (proteins, nucleic acids and small chemicals) into exosomes, the design strategies for cell and tissue targeting, and the factors for exosome formation. This review can be used as a reference for further research as well as for the development of therapeutic exosomes.

A biomimetic cascade nanoreactor for tumor targeted starvation therapy-amplified chemotherapy

Targeted drug delivery with precisely controlled drug release and activation is highly demanding and challenging for tumor precision therapy. Herein, a biomimetic cascade nanoreactor (designated as Mem@GOx@ZIF-8@BDOX) is constructed for tumor targeted starvation therapy-amplified chemotherapy by assembling tumor cell membrane cloak and glucose oxidase (GOx) onto zeolitic imidazolate framework (ZIF-8) with the loading prodrug of hydrogen peroxide (H₂O₂)-sensitive BDOX. Biomimetic membrane camouflage affords superior immune evasion and homotypic binding capacities, which significantly enhance the tumor preferential accumulation and uptake for targeted drug delivery. Moreover, GOx-induced glycolysis would cut off glucose supply and metabolism pathways for tumor starvation therapy with the transformation of tumor microenvironments. Importantly, this artificial adjustment could trigger the site-specific BDOX release and activation for cascade amplified tumor chemotherapy regardless of the complexity and variability of tumor physiological environments. Both in vitro and in vivo investigations indicate that the biomimetic cascade nanoreactor could remarkably improve the therapeutic efficacy with minimized side effects through the synergistic starvation therapy and chemotherapy. This biomimetic cascade strategy would contribute to developing intelligent drug delivery systems for tumor precision therapy.