Targeting central nervous system extracellular vesicles enhanced triiodothyronine remyelination effect on experimental autoimmune encephalomyelitis

Targeting of Extracellular Vesicle-Based Therapeutics to the Brain

Extracellular vesicles (EVs) have been explored as promising vehicles for drug delivery. One of the most valuable features of EVs is their ability to cross physiological barriers, particularly the blood-brain barrier (BBB). This significantly enhances the development of EV-based drug delivery systems for the treatment of CNS disorders. The present review focuses on the factors and techniques that contribute to the successful delivery of EV-based therapeutics to the brain. Here, we discuss the major methods of brain targeting which includes the utilization of different administration routes, capitalizing on the biological origins of EVs, and the modification of EVs through the addition of specific ligands on to the surface of EVs. Finally, we discuss the current challenges in large-scale EV production and drug loading while highlighting future perspectives regarding the application of EV-based therapeutics for brain delivery.

Inflammation-Targeted Biomimetic Nano-Decoys via Inhibiting the Infiltration of Immune Cells and Effectively Delivering Glucocorticoids for Enhanced Multiple Sclerosis Treatment

Excessive infiltration of neutrophil and inflammatory cytokines accumulation as well as the inadequate delivery of drugs to the targeted site are key pathological cascades in multiple sclerosis (MS). Herein, inflammation-targeting biomimetic nano-decoys (TFMN) is developed that inhibit the infiltration of immune cells and effectively deliver glucocorticoids to lesions for enhanced MS treatment. Nano-decoys encapsulated with the glucocorticoid methylprednisolone (MPS) are prepared by coating neutrophil membrane (NM) on nanoparticles formed by the self-assembly of tannic acid and poloxamer188/pluronic68. Benefiting from the natural inflammation-targeting ability of activated neutrophil membranes, TFMN can target the lesion site and prevent neutrophils infiltration by adsorbing and neutralizing elevated neutrophil-related cytokines, subsequently modulating the inflammatory microenvironment in experimental autoimmune encephalomyelitis mice. TFMN exhibits a strong antioxidant capacity and scavenged excessive reactive oxygen species to enhance neuronal protection. Furthermore, at the inflammation site, perforin, discharged by cytotoxic T-lymphocytes, triggered the controlled release of MPS within the TFMN through perforin-formed pores in the NM. Simultaneously, this mechanism protected neurons from perforin-induced toxicity. The MPS liberated at the targeted site achieves optimal drug accumulation, thereby enhancing therapeutic efficacy. In conclusion, the innovative system shows potential for integrating various therapeutic agents, offering a novel strategy for CNS disorders.

Targeted Drug Delivery to ACE2+ Cells Using Engineered Extracellular Vesicles: A Potential Therapeutic Approach for COVID-19

BACKGROUND

Extracellular vesicles (EVs) are emerging as potential drug carriers in the fight against COVID-19. This study investigates the ability of EVs as drug carriers to target SARS-CoV-2-infected cells.

METHODS

EVs were modified using Xstamp technology to carry the virus's RBD, enhancing targeting ability to hACE2+ cells and improving drug delivery efficiency. Characterization confirmed EVs' suitability as drug carriers. For in vitro tests, A549, Caco-2, and 4T1 cells were used to assess the targeting specificity of EVRs (EVs with membrane-surface enriched RBD). Moreover, we utilized an ex vivo lung tissue model overexpressing hACE2 as an ex vivo model to confirm the targeting capability of EVRs toward lung tissue. The study also evaluated drug loading efficiency and assessed the potential of the anti-inflammatory activity on A549 lung cancer cells exposed to lipopolysaccharide.

RESULTS

The results demonstrate the successful construction of RBD-fused EVRs on the membrane- surface. In both in vitro and ex vivo models, EVRs significantly enhance their targeting ability towards hACE2+ cells, rendering them a safe and efficient drug carrier. Furthermore, ultrasound loading efficiently incorporates IL-10 into EVRs, establishing an effective drug delivery system that ameliorates the pro-inflammatory response induced by LPS-stimulated A549 cells.

CONCLUSION

These findings indicate promising opportunities for engineered EVs as a novel nanomedicine carrier, offering valuable insights for therapeutic strategies against COVID-19 and other diseases.

Autophagy in Multiple Sclerosis: Phagocytosis and Autophagy of Oligodendrocyte Precursor Cells

Multiple sclerosis (MS) is a leading cause of chronic neurological dysfunction in young to middle-aged adults, affecting approximately 2.5 million people worldwide. It is characterized by inflammation, multifocal demyelination, axonal loss, and white and gray matter gliosis. Autophagy is a highly conserved protein degradation pathway. Polymorphisms in autophagy-related genes have been implicated in a variety of autoimmune diseases, including systemic lupus erythematosus, rheumatoid arthritis, psoriasis and MS. However, the significance of autophagy in MS remains to be elucidated. This paper aims to explore the potential role of autophagy-related genes in MS diseases by using bioinformatics combined with machine learning methods. Finally, we obtained 9 autophagy genes with the highest correlation with MS, and further changes in these autophagy genes were verified in the experimental autoimmune encephalomyelitis (EAE) model and oligodendrocyte precursor cells (OPCs) engulfed myelin debris (MD). Combined with bioinformatic analysis and experimental data, Becn1 showed obvious expression abnormalities suggesting that this gene has vital functions in autophagy and MD engulfed by OPCs. This work will be of great significance for the further exploration of autophagy-related genes in demyelinating diseases.

Stem Cell Derived Extracellular Vesicle Therapy for Multiple Sclerosis, A Systematic Review and Meta-Analysis of Preclinical Studies

Stem cell therapy holds promise for multiple sclerosis (MS), with efficacy of different stem cell types reported across a range of preclinical MS animal models. While stem cell therapy has been approved for a small number of diseases in humans, extracellular vesicles (EVs) may provide an efficacious, cost-effective, and safer alternative to stem cell therapy. To this end, we conducted a systematic review with meta-analysis to assess the effectiveness of stem cell-derived secretome (EV and conditioned media (CM)) in animal models of MS. The data were extracted to calculate standardized mean differences for primary outcome measure of disease severity, using a random effect model. Additionally, several subgroup analyses were conducted to assess the impact of various study variables such as stem cell type and source, stem cell modification, route and time of administration, number of animals and animal's age, and EV isolation methods on secondary outcome. Publication quality and risk of bias were assessed. Overall, 19 preclinical studies were included in the meta-analysis where stem cell EV/CM was found to significantly reduce disease severity in EV-treated (SMD = 2, 95% CI: 1.18-2.83, P < .00001) and CM-treated animals (SMD = 2.58, 95% CI: 1.34-3.83, P < .00001) compared with controls. Our analysis indicated that stem cell secretome has a positive effect on reducing demyelination, systemic neuroinflammation, and disease severity in preclinical models of MS. These findings indicate a potential therapeutic effect that merits investigation and validation in clinical settings.

Exosomes in Action: Unraveling Their Role in Autoimmune Diseases and Exploring Potential Therapeutic Applications

Exosomes are double phospholipid membrane vesicles that are synthesized and secreted by a variety of cells, including T cells, B cells, dendritic cells, immune cells, are extracellular vesicles. Recent studies have revealed that exosomes can play a significant role in under both physiological and pathological conditions. They have been implicated in regulation of inflammatory responses, immune response, angiogenesis, tissue repair, and antioxidant activities, particularly in modulating immunity in autoimmune diseases (AIDs). Moreover, variations in the expression of exosome-related substances, such as miRNA and proteins, may not only offer valuable perspectives for the early warning, and prognostic assessment of various AIDs, but may also serve as novel markers for disease diagnosis. This article examines the impact of exosomes on the development of AIDs and explores their potential for therapeutic application.

Emerging technologies for engineering of extracellular vesicles

Extracellular vesicles (EVs) are lipid-bilayer membrane-enclosed vesicles that are secreted by all cell types. Natural EVs contain biological information such as proteins, nucleic acids, and lipids from their parent cells. Therefore, EVs have been extensively studied as diagnostic biomarkers and therapeutic tools under normal and pathological conditions. However, some drawbacks, including low yield, poor therapeutic effects, lack of imaging, and targeting capacity of natural EVs, still need to be improved. Emerging engineering technologies have rendered EVs new properties or functionalities that broadened their applications in the biomedical field. Herein, in this review, we gave a brief overview of advanced strategies for EV engineering. We focused on pre-treatment of parent cells to regulate their released EVs. Meanwhile, we summarized and discussed the direct modification of EVs to achieve drug loading, imaging, and targeting functionalities for downstream applications.

Combination Therapy with Resveratrol and Celastrol Using Folic Acid-Functionalized Exosomes Enhances the Therapeutic Efficacy of Sepsis

Overactivated macrophages are a prominent feature of many inflammatory and autoimmune diseases, including sepsis. Attention and regulation of macrophages activity is of great significance for sepsis treatment. Herein, this study shows that folic acid-functionalized exosomes accumulate in the lung of septic mice and specifically target inflammatory macrophages. Therefore, FA-functionalized exosomes co-loaded with resveratrol (an anti-inflammatory polyphenol) and celastrol (an immunosuppressive pentacyclic triterpenoid; FA-Exo/R+C), which exhibit powerful anti-inflammatory and immunosuppressive activities against LPS-stimulated macrophages in vitro by regulating NF-κB and ERK1/2 signaling pathways, are designed. Encouraged by these positive data, the efficacy of FA-Exo/R+C is systematically investigated in an LPS-induced mouse sepsis model. FA-Exo/R+C shows striking therapeutic benefits in terms of attenuated cytokine storm, reduced acute lung injury, and increased survival of septic mice by inhibiting the inflammation and proliferation of proinflammatory M1 macrophages. Importantly, multiple administrations of FA-Exo/R+C significantly enhance and prolong the protective effect, and resist rechallenge to LPS. Collectively, the strategy of co-delivering drugs combination through functionalized exosomes offers a new avenue for sepsis treatment.

Neural stem cell-derived extracellular vesicles: The light of central nervous system diseases

Central nervous system (CNS) diseases are the leading cause of death worldwide. By performing compensatory functions and improving the inflammatory microenvironment, the transplantation of neural stem cells (NSCs) can promote functional recovery from brain injury, aging, brain tumours, and other diseases. However, the ability of NSCs to differentiate into neurons is limited, and they are associated with a risk of tumourigenicity. NSC-derived extracellular vesicles (NSC-EVs) can modulate the local microenvironment of the nervous system as well as distant neuronal functions. Thus, cell-free therapy may be a novel remedy for CNS disorders. This article reviews the characteristics, contents, and mechanisms of action of NSC-EVs as well as their roles and application prospects in various CNS diseases.

Extracellular vesicles: a rising star for therapeutics and drug delivery

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

An appraisal of emerging therapeutic targets for multiple sclerosis derived from current preclinical models

INTRODUCTION

Multiple sclerosis (MS) is a chronic inflammatory, demyelinating, and neurodegenerative condition affecting the central nervous system (CNS). Although therapeutic approaches have become available over the last 20 years that markedly slow the progression of disease, there is no cure for MS. Furthermore, the capacity to repair existing CNS damage caused by MS remains very limited.

AREAS COVERED

Several animal models are widely used in MS research to identify potential druggable targets for new treatment of MS. In this review, we look at targets identified since 2019 in studies using these models, and their potential for effecting a cure for MS.

EXPERT OPINION

Refinement of therapeutic strategies targeting key molecules involved in the activation of immune cells, cytokine, and chemokine signaling, and the polarization of the immune response have dominated recent publications. While some progress has been made in identifying effective targets to combat chronic demyelination and neurodegeneration, much more work is required. Progress is largely limited by the gaps in knowledge of how the immune system and the nervous system interact in MS and its animal models, and whether the numerous targets present in both systems respond in the same way in each system to the same therapeutic manipulation.

Engineered extracellular vesicles for delivery of siRNA promoting targeted repair of traumatic spinal cord injury

Spinal cord injury (SCI) is a severe disease of the nervous system that causes irreparable damage and loss of function, for which no effective treatments are available to date. Engineered extracellular vesicles (EVs) carrying therapeutic molecules hold promise as an alternative SCI therapy depending on the specific functionalized EVs and the appropriate engineering strategy. In this study, we demonstrated the design of a drug delivery system of peptide CAQK-modified, siRNA-loaded EVs (C-EVs-siRNA) for SCI-targeted therapy. The peptide CAQK was anchored through a chemical modification to the membranes of EVs isolated from induced neural stem cells (iNSCs). CCL2-siRNA was then loaded into the EVs through electroporation. The modified EVs still maintained the basic properties of EVs and showed favorable targeting and therapeutic effects in vitro and in vivo. C-EVs-siRNA specifically delivered siRNA to the SCI region and was taken up by target cells. C-EVs-siRNA used the inherent anti-inflammatory and neuroreparative functions of iNSCs-derived EVs in synergy with the loaded siRNA, thus enhancing the therapeutic effect against SCI. The combination of targeted modified EVs and siRNA effectively regulated the microenvironmental disturbance after SCI, promoted the transformation of microglia/macrophages from M1 to M2 and limited the negative effects of the inflammatory response and neuronal injury on functional recovery in mice after SCI. Thus, engineered EVs are a potentially feasible and efficacious treatment for SCI, and may also be used to develop targeted treatments for other diseases.

Resveratrol-loaded macrophage exosomes alleviate multiple sclerosis through targeting microglia

Despite exosome promise as endogenous drug delivery vehicles, the current understanding of exosome may be insufficient to develop their various applications. Here we synthesized five sialic acid analogues with different length N-acyl side chains and screened out the optimal metabolic precursor for exosome labeling via bio-orthogonal click chemistry. In proof-of-principle labeling experiments, exosomes derived from macrophages (RAW-Exo) strongly co-localized with central nervous system (CNS) microglia. Inspired by this discovery, we developed a resveratrol-loaded RAW-Exo formulation (RSV&Exo) for multiple sclerosis (MS) treatment. Intranasal administration of RSV&Exo significantly inhibited inflammatory responses in the CNS and peripheral system in a mouse model of MS and effectively improved the clinical evolution of MS in vivo. These findings suggested the feasibility and efficacy of engineered RSV&Exo administration for MS, providing a potential therapeutic strategy for CNS diseases.

Extracellular Vesicle-Based Therapeutics in Neurological Disorders

Neurological diseases remain some of the major causes of death and disability in the world. Few types of drugs and insufficient delivery across the blood-brain barrier limit the treatment of neurological disorders. The past two decades have seen the rapid development of extracellular vesicle-based therapeutics in many fields. As the physiological and pathophysiological roles of extracellular vesicles are recognized in neurological diseases, they have become promising therapeutics and targets for therapeutic interventions. Moreover, advanced nanomedicine technologies have explored the potential of extracellular vesicles as drug delivery systems in neurological diseases. In this review, we discussed the preclinical strategies for extracellular vesicle-based therapeutics in neurological disorders and the struggles involved in their clinical application.

Extracellular Vesicles in Chronic Demyelinating Diseases: Prospects in Treatment and Diagnosis of Autoimmune Neurological Disorders

Extracellular vesicles (EVs) represent membrane-enclosed structures that are likely to be secreted by all living cell types in the animal organism, including cells of peripheral (PNS) and central nervous systems (CNS). The ability to cross the blood-brain barrier (BBB) provides the possibility not only for various EV-loaded molecules to be delivered to the brain tissues but also for the CNS-to-periphery transmission of these molecules. Since neural EVs transfer proteins and RNAs are both responsible for functional intercellular communication and involved in the pathogenesis of neurodegenerative diseases, they represent attractive diagnostic and therapeutic targets. Here, we discuss EVs' role in maintaining the living organisms' function and describe deviations in EVs' structure and malfunctioning during various neurodegenerative diseases.

Phospholipid-Membrane-Based Nanovesicles Acting as Vaccines for Tumor Immunotherapy: Classification, Mechanisms and Applications

Membrane vesicles, a group of nano- or microsized vesicles, can be internalized or interact with the recipient cells, depending on their parental cells, size, structure and content. Membrane vesicles fuse with the target cell membrane, or they bind to the receptors on the cell surface, to transfer special effects. Based on versatile features, they can modulate the functions of immune cells and therefore influence immune responses. In the field of tumor therapeutic applications, phospholipid-membrane-based nanovesicles attract increased interest. Academic institutions and industrial companies are putting in effort to design, modify and apply membrane vesicles as potential tumor vaccines contributing to tumor immunotherapy. This review focuses on the currently most-used types of membrane vesicles (including liposomes, bacterial membrane vesicles, tumor- and dendritic-cell-derived extracellular vesicles) acting as tumor vaccines, and describes the classification, mechanism and application of these nanovesicles.

Biomaterials constructed for MSC-derived extracellular vesicle loading and delivery—a promising method for tissue regeneration

Mesenchymal stem cells (MSCs) have become the preferred seed cells for tissue regeneration. Nevertheless, due to their immunogenicity and tumorigenicity, MSC transplantation remains questionable. Extracellular vesicles (EVs) derived from MSCs are becoming a promising substitute for MSCs. As a route of the MSC paracrine, EVs have a nano-sized and bilayer lipid-enclosed structure, which can guarantee the integrity of their cargoes, but EVs cannot obtain full function in vivo because of the rapid biodegradation and clearance by phagocytosis. To improve the efficacy and targeting of EVs, methods have been proposed and put into practice, especially engineered vesicles and EV-controlled release systems. In particular, EVs can be cell or tissue targeting because they have cell-specific ligands on their surfaces, but their targeting ability may be eliminated by the biodegradation of the phagocytic system during circulation. Novel application strategies have been proposed beyond direct injecting. EV carriers such as biodegradable hydrogels and other loading systems have been applied in tissue regeneration, and EV engineering is also a brand-new method for higher efficacy. In this review, we distinctively summarize EV engineering and loading system construction methods, emphasizing targeting modification methods and controlled release systems for EVs, which few literature reviews have involved.

Tailored Extracellular Vesicles: Novel Tool for Tissue Regeneration

Extracellular vesicles (EVs) play an essential part in multiple pathophysiological processes including tissue injury and regeneration because of their inherent characteristics of small size, low immunogenicity and toxicity, and capability of carrying a variety of bioactive molecules and mediating intercellular communication. Nevertheless, accumulating studies have shown that the application of EVs faces many challenges such as insufficient therapeutic efficacy, a lack of targeting capability, low yield, and rapid clearance from the body. It is known that EVs can be engineered, modified, and designed to encapsulate therapeutic cargos like proteins, peptides, nucleic acids, and drugs to improve their therapeutic efficacy. Targeted peptides, antibodies, aptamers, magnetic nanoparticles, and proteins are introduced to modify various cell-derived EVs for increasing targeting ability. In addition, extracellular vesicle mimetics (EMs) and self-assembly EV-mimicking nanocomplex are applied to improve production and simplify EV purification process. The combination of EVs with biomaterials like hydrogel, and scaffolds dressing endows EVs with long-term therapeutic efficacy and synergistically enhanced regenerative outcome. Thus, we will summarize recent developments of EV modification strategies for more extraordinary regenerative effect in various tissue injury repair. Subsequently, opportunities and challenges of promoting the clinical application of engineered EVs will be discussed.

Extracellular Vesicles for Immunomodulation in Tissue Regeneration

A large number of people suffer from tissue injury and defect worldwide, which constitutes a critical challenge for regenerative medicine. During the complicated process of tissue repair and regeneration, immune response that involves many kinds of immune cells often concurrently exists and plays a significant role, thus providing a promising target for the development of therapeutic strategies. As a critical player in cell-cell communication, extracellular vesicles (EVs) are a cluster of nano-sized vesicles of different categories, which have been reported to possess favorable immunoregulatory potential, and participate in the process of tissue repair and regeneration. Furthermore, EVs can be engineered with genetic or chemical strategies for optimized performance as therapeutic mediators. Here, we provide an outline on the biology of EVs as well as the role of EVs in immune regulation, focusing on exosomes, microvesicles, and apoptotic vesicles. We further summarize the applications of EV-based therapies for tissue regeneration, with particular emphasis on the modulation of immune system. Also, we have discussed the construction strategies of engineered EVs and the immunomodulatory capability of engineered EVs as well as their therapeutic potential in tissue repair. This review will highlight the outstanding potential of EV-based therapeutic strategies for tissue repair and regeneration.

Analysis of 5-Methylcytosine Regulators and DNA Methylation-Driven Genes in Colon Cancer

Background: Epigenetic-driven events are important molecular mechanisms of carcinogenesis. The 5-methylcytosine (5mC) regulators play important roles in the methylation-driven gene expression. However, the effect of the 5mC regulators on the oncogenic pathways in colon cancer (CC) remains unclear. Also, the clinical value of such epigenetic-driven events needs further research.

Methods: The transcriptome and matching epigenetic data were obtained from The Cancer Genome Atlas dataset. The gene set variation analysis identified the oncogenic pathways adjusted by 5mC regulators. The “edgeR” and “methylmix” package identified the differential expression genes of DNA methylation-driven genes. The correlation between 5mC regulators or transcription factors and shortlisted genes was investigated by calculating the Spearman's rank correlation coefficient. Among them, the genes related to diagnosis were screened out based on differential gene expression in extracellular vesicles (EVs) by the “limma” package and histology by immunohistochemistry. Then, a risk signature was constructed by fitting the generalized linear model and validated by the receiver operating characteristic curve.

Results: MYC targets pathway and phosphatidylinositol-3-kinase–AKT–mammalian target of rapamycin signaling pathway were identified as the hallmark-related pathways associated with 5mC regulators. Also, the P53 pathway was subject to the influence of regulators' expression. A five methylation-driven gene signature (FIRRE, MYBL2, TGFBI, AXIN2, and SLC35D3) was developed as the biomarker for CC diagnosis. Meanwhile, those genes positively related to 5mC regulators and interacted with their relevant or transcription factors.

Conclusion: In general, 5mC regulators are positively related to each other and DNA methylation-driven genes, with the relationship of multiple active and inhibitory pathways related to cancer. Meanwhile, the signature (FIRRE, MYBL2, TGFBI, AXIN2, and SLC35D3) can prefigure prospective diagnosis in CC.

Engineered extracellular vesicles encapsulated Bryostatin-1 as therapy for neuroinflammation

Targeted and effective drug delivery to central nervous system (CNS) lesions is a major challenge in the treatment of multiple sclerosis (MS). Extracellular vesicles (EVs) have great promise as a drug delivery nanosystem given their unique characteristics, including a strong cargo-loading capacity, low immunogenicity, high biocompatibility, inherent stability, high delivery efficiency, ease of manipulation, and blood-brain barrier (BBB) penetration. Clinical applications are, however, limited by their insufficient targeting capability and "dilution effects" upon systemic administration. Neural stem cells (NSCs) provide an abundant source of EVs because of their remarkable capacity for self-renewal. Here, we developed a novel therapeutic strategy for local delivery and treatment using EVPs, which are derived from NSCs with the expression of the CNS lesion targeting ligand-PDGFRα. Furthermore, we used EVPs as a targeting carrier for encapsulating Bryostatin-1 (Bryo-1), a natural compound with remarkable anti-inflammation ability. Our data showed that Bryo-1 delivered by EVPs was more stable and concentrated in the CNS than native Bryo-1. Systemic injection of a low dosage (1 × 10⁸ particles) of EVPs + Bryo-1, versus only EVPs or Bryo-1 administration, significantly ameliorated clinical disease development, decreased the infiltration of pro-inflammatory cells, blocked myelin loss and astrogliosis, protected BBB integrity, and altered microglia pro-inflammatory phenotype in the CNS of EAE mice. Taken as a whole, our study showed that engineered EVs have a CNS targeting capacity, and it provides potentially powerful therapeutic effects for the treatment of various neuroinflammatory diseases.