Exosomes function in cell-cell communication during brain circuit development

Small Differences and Big Changes: The Many Variables of MicroRNA Expression and Function in the Brain

MicroRNAs are emerging as crucial regulators within the complex, dynamic environment of the synapse, and they offer a promising new avenue for the treatment of neurological disease. These small noncoding RNAs modify gene expression in several ways, including posttranscriptional modulation via binding to complementary and semicomplementary sites on target mRNAs. This rapid, finely tuned regulation of gene expression is essential to meet the dynamic demands of the synapse. Here, we provide a detailed review of the multifaceted world of synaptic microRNA regulation. We discuss the many mechanisms by which microRNAs regulate gene expression at the synapse, particularly in the context of neuronal plasticity. We also describe the various factors, such as age, sex, and neurological disease, that can influence microRNA expression and activity in neurons. In summary, microRNAs play a crucial role in the intricate and quickly changing functional requirements of the synapse, and context is essential in the study of microRNAs and their potential therapeutic applications.

Stem cell grafts enhance endogenous extracellular vesicle expression in the stroke brain

Endogenous brain repair occurs following an ischemic stroke but is transient, thus unable to fully mount a neuroprotective response against the evolving secondary cell death. Finding a treatment strategy that may render robust and long-lasting therapeutic effects stands as a clinically relevant therapy for stroke. Extracellular vesicles appear to be upregulated after stroke, which may represent a candidate target for neuroprotection. In this study, we probed whether transplanted stem cells could enhance the expression of extracellular vesicles to afford stable tissue remodeling in the ischemic stroke brain. Aged rats were initially exposed to the established ischemic stroke model of middle cerebral artery occlusion then received intravenous delivery of either bone marrow-derived mesenchymal stem cell transplantation or vehicle. A year later, the animals were assayed for brain damage, inflammation, and extracellular vesicle expression. Our findings revealed that while core infarction was not reduced, the stroke animals transplanted with stem cells displayed a significant reduction in peri-infarct cell loss that coincided with downregulated Iba1-labeled inflammatory cells and upregulated CD63-positive extracellular vesicles that appeared to be co-localized with GFAP-positive astrocytes. Interestingly, grafted stem cells were not detected at one year post-transplantation period, suggesting that the extracellular vesicles likely originated within the host brain. That long-lasting functional benefits persisted in the absence of surviving transplanted stem cells, but with upregulation of endogenous extracellular vesicles, advances the concept that transplantation of stem cells acutely after stroke propels host extracellular vesicles to the ischemic brain, altogether promoting chronic brain remodeling.

Astrocyte modulation of synaptic plasticity mediated by activity-dependent Sonic hedgehog signaling

The influence of neural activity on astrocytes and their reciprocal interactions with neurons has emerged as an important modulator of synapse function. Astrocytes exhibit activity-dependent changes in gene expression, yet the molecular mechanisms by which they accomplish this have remained largely unknown. The molecular signaling pathway, Sonic hedgehog (Shh), mediates neuron-astrocyte communication and regulates the organization of cortical synapses. Here, we demonstrate that neural activity stimulates Shh signaling in cortical astrocytes and upregulates expression of Hevin and SPARC, astrocyte derived molecules that modify synapses. Whisker stimulation and chemogenetic activation both increase Shh activity in deep layers of the somatosensory cortex, where neuron-astrocyte Shh signaling is predominantly found. Experience-dependent Hevin and SPARC require intact Shh signaling and selective loss of pathway activity in astrocytes occludes experience-dependent structural plasticity. Taken together, these data identify Shh signaling as an activity-dependent, neuronal derived cue that stimulates astrocyte interactions with synapses and promotes synaptic plasticity.

Stem cell-derived extracellular vesicles in the therapeutic intervention of Alzheimer's Disease, Parkinson's Disease, and stroke

With the increase in the aging population, the occurrence of neurological disorders is rising. Recently, stem cell therapy has garnered attention due to its convenient sourcing, minimal invasiveness, and capacity for directed differentiation. However, there are some disadvantages, such as poor quality control, safety assessments, and ethical and logistical issues. Consequently, scientists have started to shift their attention from stem cells to extracellular vesicles due to their similar structures and properties. Beyond these parallels, extracellular vesicles can enhance biocompatibility, facilitate easy traversal of barriers, and minimize side effects. Furthermore, stem cell-derived extracellular vesicles can be engineered to load drugs and modify surfaces to enhance treatment outcomes. In this review, we summarize the functions of native stem cell-derived extracellular vesicles, subsequently review the strategies for the engineering of stem cell-derived extracellular vesicles and their applications in Alzheimer's disease, Parkinson's disease, and stroke, and discuss the challenges and solutions associated with the clinical translation of stem cell-derived extracellular vesicles.

A review on separation and application of plant-derived exosome-like nanoparticles

Exosomes-like nanoparticles (ELNs) (exosomes or extracellular vesicles) are vesicle-like bodies secreted by cells. Plant ELNs (PENs) are membrane vesicles secreted by plant cells, with a lipid bilayer as the basic skeleton, enclosing various active substances such as proteins and nucleic acids, which have many physiological and pathological functions. Recent studies have found that the PENs are widespread within different plant species and their biological functions are increasingly recognized. The effective separation method is also necessary for its function and application. Ultracentrifugation, sucrose density gradient ultracentrifugation, ultrafiltration, polymer-based precipitation methods, etc., are commonly used methods for plant exosome-like nanoparticle extraction. In recent years, emerging methods such as size exclusion chromatography, immunoaffinity capture-based technique, and microfluidic technology have shown advancements compared to traditional methods. The standardized separation process for PENs continues to evolve. In this review, we summarized the recent progress in the biogenesis, components, separation methods, and some functions of PENs. When the research on the separation method of PENs and their unique biological structure is further studied. A brand-new idea for the efficient separation and utilization of PENs can be provided in the future, which has a very broad prospect.

Label-free, whole-brain in vivo mapping in an adult vertebrate with third harmonic generation microscopy

Comprehensive understanding of interconnected networks within the brain requires access to high resolution information within large field of views and over time. Currently, methods that enable mapping structural changes of the entire brain in vivo are extremely limited. Third harmonic generation (THG) can resolve myelinated structures, blood vessels, and cell bodies throughout the brain without the need for any exogenous labeling. Together with deep penetration of long wavelengths, this enables in vivo brain-mapping of large fractions of the brain in small animals and over time. Here, we demonstrate that THG microscopy allows non-invasive label-free mapping of the entire brain of an adult vertebrate, Danionella dracula, which is a miniature species of cyprinid fish. We show this capability in multiple brain regions and in particular the identification of major commissural fiber bundles in the midbrain and the hindbrain. These features provide readily discernable landmarks for navigation and identification of regional-specific neuronal groups and even single neurons during in vivo experiments. We further show how this label-free technique can easily be coupled with fluorescence microscopy and used as a comparative tool for studies of other species with similar body features to Danionella, such as zebrafish (Danio rerio) and tetras (Trochilocharax ornatus). This new evidence, building on previous studies, demonstrates how small size and relative transparency, combined with the unique capabilities of THG microscopy, can enable label-free access to the entire adult vertebrate brain.

Extracellular vesicle proteome unveils cathepsin B connection to Alzheimer's disease pathogenesis

Extracellular vesicles (EVs) are membrane vesicles that are released extracellularly and considered to be implicated in the pathogenesis of neurodegenerative diseases including Alzheimer's disease. Here, CSF EVs of 16 ATN-classified cases were subjected to quantitative proteome analysis. In these CSF EVs, levels of 11 proteins were significantly altered during the ATN stage transitions (P < 0.05 and fold-change > 2.0). These proteins were thought to be associated with Alzheimer's disease pathogenesis and represent candidate biomarkers for pathogenic stage classification. Enzyme-linked immunosorbent assay analysis of CSF and plasma EVs revealed altered levels of cathepsin B (CatB) during the ATN transition (seven ATN groups in validation set, n = 136). The CSF and plasma EV CatB levels showed a negative correlation with CSF amyloid-β42 concentrations. This proteomic landscape of CSF EVs in ATN classifications can depict the molecular framework of Alzheimer's disease progression, and CatB may be considered a promising candidate biomarker and therapeutic target in Alzheimer's disease amyloid pathology.

Cholesterol-linoleic acid liposomes induced extracellular vesicles secretion from immortalized adipose-derived mesenchymal stem cells for in vitro cell migration

Extracellular vesicles (EVs) are small vesicles that are naturally released by cells and play a crucial role in cell-to-cell communication, tissue repair and regeneration. As naturally secreted EVs are limited, liposomes with different physicochemical properties, such as 1,2-dioleoyl-3-trimethylammonium propane (DOTAP) and linoleic acid (LA) with modifications have been formulated to improve EVs secretion for in vitro wound healing. Various analyses, including dynamic light scattering (DLS) and transmission electron microscopy (TEM) were performed to monitor the successful preparation of different types of liposomes. The results showed that cholesterol-LA liposomes significantly improved the secretion of EVs from immortalized adipose-derived mesenchymal stem cells (AD-MSCs) by 1.5-fold. Based on the cell migration effects obtained from scratch assay, both LA liposomal-induced EVs and cholesterol-LA liposomal-induced EVs significantly enhanced the migration of human keratinocytes (HaCaT) cell line. These findings suggested that LA and cholesterol-LA liposomes that enhance EVs secretion are potentially useful and can be extended for various tissue regeneration applications.

Blood exosome sensing via neuronal insulin-like growth factor-1 regulates autism-related phenotypes

The development and progression of autism spectrum disorder (ASD) is characterized by multiple complex molecular events, highlighting the importance of the prefrontal brain regions in this process. Exosomes are nanovesicles that play a critical role in intercellular communication. Peripheral systems influence brain function under both physiological and pathological conditions. We investigated whether this influence was mediated by the direct sensing of peripheral blood exosomes by brain cells. Administration of serum exosomes from rats with valproic acid-induced ASD resulted in ASD-related phenotypes in mice, whereas exosomes from normal rats did not exhibit such effects. RNA sequencing and bioinformatics analysis suggested that negative regulation of medial prefrontal cortex (mPFC) insulin-like growth factor 1 (IGF-1) by exosome-derived miR-29b-3p may contribute to these ASD-associated effects. Further evidence showed that miR-29b-3p-enriched exosomes crossed the blood-brain barrier to reach the mPFC, subsequently inducing the suppression of IGF-1 expression in neurons. Optogenetic activation of excitatory neurons in the mPFC improved behavioral abnormalities in exosome-treated mice. The addition of exogenous IGF-1 or inhibition of miR-29b-3p expression in the mPFC also rescued the ASD-related phenotypes in mice. Importantly, administration of miR-29b-3p-enriched serum exosomes from human donors with ASD into the mouse medial prefrontal cortex was sufficient to induce hallmark ASD behaviors. Together, our findings indicate that blood-brain cross-talk is crucial for ASD pathophysiology and that the brain may sense peripheral system changes through exosomes, which could serve as the basis for future neurological therapies.

Neutrophil membrane-based nanotherapeutics: Propitious paradigm shift in the management of cancer

Cancer is the leading cause of death across the globe, with 19.3 million new cancer cases and 10 million deaths in the year 2020. Conventional treatment modalities have numerous pitfalls, such as off-site cytotoxicity and poor bioavailability. Nanocarriers (NCs) have been explored to deliver various therapeutic moieties such as chemotherapeutic agents and photothermal agents, etc. However, several limitations, such as rapid clearance by the reticuloendothelial system, poor extravasation into the tumor microenvironment, and low systemic half-life are roadblocks to successful clinical translation. To circumvent the pitfalls of currently available treatment modalities, neutrophil membrane (NM)-based nanotherapeutics have emerged as a promising platform for cancer management. Their versatile features such as natural tumor tropism, tumor-specific accumulation, and prevention from rapid clearance owing to their autologous nature make them an effective anticancer NCs. In this manuscript, we have discussed various methods for isolation, coating and characterization of NM. We have discussed the role of NM-coated nanotherapeutics as neoadjuvant and adjuvant in different treatment modalities, such as chemotherapy, photothermal and photodynamic therapies with rationales behind their inclusion. Clinical hurdles faced during the bench-to-bedside translation with possible solutions have been discussed. We believe that in the upcoming years, NM-coated nanotherapeutics will open a new horizon in cancer management.

The role of exosomes in cancer biology by shedding light on their lipid contents

Exosomes are extracellular bilayer membrane nanovesicles released by cells after the fusion of multivesicular bodies (MVBs) with the plasma membrane. One of the interesting features of exosomes is their ability to carry and transfer various molecules, including lipids, proteins, nucleic acids, and therapeutic cargoes among cells. As intercellular signaling organelles, exosomes participate in various signaling processes such as tumor growth, metastasis, angiogenesis, epithelial-to-mesenchymal transition (EMT), and cell physiology such as cell-to-cell communication. Moreover, these particles are considered good vehicles to shuttle vaccines and drugs for therapeutic applications regarding cancers and tumor cells. These bioactive vesicles are also rich in various lipid molecules such as cholesterol, sphingomyelin (SM), glycosphingolipids, and phosphatidylserine (PS). These lipids play an important role in the formation, release, and function of the exosomes and interestingly, some lipids are used as biomarkers in cancer diagnosis. This review aimed to focus on exosomes lipid content and their role in cancer biology.

Exosome-shuttled miR-126 mediates ethanol-induced disruption of neural crest cell-placode cell interaction by targeting SDF1

During embryonic development, 2 populations of multipotent stem cells, cranial neural crest cells (NCCs) and epibranchial placode cells (PCs), are anatomically adjacent to each other. The coordinated migration of NCCs and PCs plays a major role in the morphogenesis of craniofacial skeletons and cranial nerves. It is known that ethanol-induced dysfunction of NCCs and PCs is a key contributor to the defects of craniofacial skeletons and cranial nerves implicated in fetal alcohol spectrum disorder (FASD). However, how ethanol disrupts the coordinated interaction between NCCs and PCs was not elucidated. To fill in this gap, we established a well-designed cell coculture system to investigate the reciprocal interaction between human NCCs (hNCCs) and human PCs (hPCs), and also monitored the migration behavior of NCCs and PCs in zebrafish embryos. We found that ethanol exposure resulted in a disruption of coordinated hNCCs-hPCs interaction, as well as in zebrafish embryos. Treating hNCCs-hPCs with exosomes derived from ethanol-exposed hNCCs (ExoEtOH) mimicked ethanol-induced impairment of hNCCs-hPCs interaction. We also observed that SDF1, a chemoattractant, was downregulated in ethanol-treated hPCs and zebrafish embryos. Meanwhile, miR-126 level in ExoEtOH was significantly higher than that in control exosomes (ExoCon). We further validated that ExoEtOH-encapsulated miR-126 from hNCCs can be transferred to hPCs to suppress SDF1 expression in hPCs. Knockdown of SDF1 replicated ethanol-induced abnormalities either in vitro or in zebrafish embryos. On the contrary, overexpression of SDF1 or inhibiting miR-126 strongly rescued ethanol-induced impairment of hNCCs-hPCs interaction and developmental defects.

Bidirectional crosstalk between the peripheral nervous system and lymphoid tissues/organs

The central nervous system (CNS) influences the immune system generally by regulating the systemic concentration of humoral substances (e.g., cortisol and epinephrine), whereas the peripheral nervous system (PNS) communicates specifically with the immune system according to local interactions/connections. An imbalance between the components of the PNS might contribute to pathogenesis and the further development of certain diseases. In this review, we have explored the "thread" (hardwiring) of the connections between the immune system (e.g., primary/secondary/tertiary lymphoid tissues/organs) and PNS (e.g., sensory, sympathetic, parasympathetic, and enteric nervous systems (ENS)) in health and disease in vitro and in vivo. Neuroimmune cell units provide an anatomical and physiological basis for bidirectional crosstalk between the PNS and the immune system in peripheral tissues, including lymphoid tissues and organs. These neuroimmune interactions/modulation studies might greatly contribute to a better understanding of the mechanisms through which the PNS possibly affects cellular and humoral-mediated immune responses or vice versa in health and diseases. Physical, chemical, pharmacological, and other manipulations of these neuroimmune interactions should bring about the development of practical therapeutic applications for certain neurological, neuroimmunological, infectious, inflammatory, and immunological disorders/diseases.

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.

Neural stem cell-derived extracellular vesicles: mini players with key roles in neurogenesis, immunomodulation, neuroprotection and aging

Neural stem/progenitor cells (NSPCs) are self-renewing and multipotent cells of the central nervous system where they give rise to neurons, astrocytes and oligodendrocytes both during embryogenesis and throughout adulthood, although only in a few discrete niches. NSPC can integrate and send a plethora of signals not only within the local microenvironment but also at distance, including the systemic macroenvironment. Extracellular vesicles (EVs) are currently envisioned as main players in cell-cell communication in basic and translational neuroscience where they are emerging as an acellular alternative in regenerative medicine. At present NSPC-derived EVs represent a largely unexplored area compared to EVs from other neural sources and EVs from other stem cells, i.e., mesenchymal stem cells. On the other hand, available data suggest that NSPC-derived EVs can play key roles on neurodevelopmental and adult neurogenesis, and they are endowed with neuroprotective and immunomodulatory properties, and even endocrine functions. In this review we specifically highlight major neurogenic and "non-neurogenic" properties of NSPC-EVs, the current knowledge on their peculiar cargos and their potential translational value.

Precise profiling of exosomal biomarkers via programmable curved plasmonic nanoarchitecture-based biosensor for clinical diagnosis of Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disease of complex pathogenesis, with overt symptoms following disease progression. Early AD diagnosis is challenging due to the lack of robust biomarkers and limited patient access to diagnostics via neuroimaging and cerebrospinal fluid (CSF) tests. Exosomes present in body fluids are attracting attention as diagnostic biomarkers that directly reflect neuropathological features within the brain. In particular, exosomal miRNAs (exomiRs) signatures are involved in AD pathogenesis, showing a different expression between patients and the healthy controls (HCs). However, low yield and high homologous nature impede the accuracy and reproducibility of exosome blood-based AD diagnostics. Here, we developed a programmable curved plasmonic nanoarchitecture-based biosensor to analyze exomiRs in clinical serum samples for accurate AD diagnosis. To allow the detection of exomiRs in serum at attomolar levels, nanospaces (e.g., nanocrevice and nanocavity) were introduced into the nanostructures to dramatically increase the spectral sensitivity by adjusting the bending angle of the plasmonic nanostructure through sodium chloride concentration control. The developed biosensor classifies individuals into AD, mild cognitive impairment (MCI) patients, and HCs through profiling and quantifying exomiRs. Furthermore, integrating analysis expression patterns of multiple exosomal biomarkers improved serum-based diagnostic performance (average accuracy of 98.22%). Therefore, precise, highly sensitive serum-derived exosomal biomarker detection-based plasmonic biosensor has a robust capacity to predict the molecular pathologic of neurodegenerative disease, progression of cognitive decline, MCI/AD conversion, as well as early diagnosis and treatment.

Blood extracellular vesicles carrying synaptic function- and brain-related proteins as potential biomarkers for Alzheimer's disease

INTRODUCTION

Objective and accessible markers for Alzheimer's disease (AD) and other dementias are critically needed.

METHODS

We identified NMDAR2A, a protein related to synaptic function, as a novel marker of central nervous system (CNS)-derived plasma extracellular vesicles (EVs) and developed a flow cytometry-based technology for detecting such plasma EVs readily. The assay was initially tested in our local cross-sectional study to distinguish AD patients from healthy controls (HCs) or from Parkinson's disease (PD) patients, followed by a validation study using an independent cohort collected from multiple medical centers (the Alzheimer's Disease Neuroimaging Initiative). Cerebrospinal fluid AD molecular signature was used to confirm diagnoses of all AD participants.

RESULTS

Likely CNS-derived EVs in plasma were significantly reduced in AD compared to HCs in both cohorts. Integrative models including CNS-derived EV markers and AD markers present on EVs reached area under the curve of 0.915 in discovery cohort and 0.810 in validation cohort.

DISCUSSION

This study demonstrated that robust and rapid analysis of individual neuron-derived synaptic function-related EVs in peripheral blood may serve as a helpful marker of synaptic dysfunction in AD and dementia.

Extracellular vesicles from the CNS play pivotal roles in neuroprotection and neurodegeneration: lessons from in vitro experiments

Intercellular communication between diverse cell types is crucial for the maintenance of the central nervous system, and exosomes have been shown to play an important role in this process. Exosomes are small extracellular vesicles (EVs) that are released by all cell types and carry cargoes that can elicit downstream effects in recipient cells. Exosomal communication in the central nervous system has been implicated in many neurodegenerative diseases, ranging from Alzheimer's disease to major depressive disorder. Though there remain many unknowns in the field of EV biology, in vitro experiments can provide many insights into their potential roles in health and disease. In this review, we discuss the findings of many in vitro EV experiments, with a focus on the potential roles in regulating cell viability, inflammation, oxidative stress, and neurite integrity in the central nervous system.

Extracellular Vesicles as Therapeutic Resources in the Clinical Environment

The native role of extracellular vesicles (EVs) in mediating the transfer of biomolecules between cells has raised the possibility to use them as therapeutic vehicles. The development of therapies based on EVs is now expanding rapidly; here we will describe the current knowledge on different key points regarding the use of EVs in a clinical setting. These points are related to cell sources of EVs, isolation, storage, and delivery methods, as well as modifications to the releasing cells for improved production of EVs. Finally, we will depict the application of EVs therapies in clinical trials, considering the impact of the COVID-19 pandemic on the development of these therapies, pointing out that although it is a promising therapy for human diseases, we are still in the initial phase of its application to patients.

iTRAQ-Based Proteomic Analysis of APP Transgenic Mouse Urine Exosomes

Alzheimer's disease (AD) is a common dementia disease in the elderly. To get a better understanding of the pathophysiology, we performed a proteomic analysis of the urine exosomes (U-exo) in AD model mice (J20). The polymer precipitation method was used to isolate U-exo from the urine of 3-month-old J20 and wild-type (WT) mice. Neuron-derived exosome (N-exo) was isolated from U-exo by immunoprecipitation. iTRAQ-based MALDI TOF MS/MS was used for proteomic analysis. The results showed that compared to WT, the levels of 61 and 92 proteins were increased in the J20 U-exo and N-exo, respectively. Gene ontology enrichment analysis demonstrated that the sphingolipid catabolic process, ceramide catabolic process, membrane lipid catabolic process, Aβ clearance, and Aβ metabolic process were highly enriched in U-exo and N-exo. Among these, Asah1 was shown to be the key protein in lipid metabolism, and clusterin, ApoE, neprilysin, and ACE were related to Aβ metabolism and clearance. Furthermore, protein-protein interaction analysis identified four protein complexes where clusterin and ApoE participated as partner proteins. Thus, J20 U-exo and N-exo contain proteins related to lipid- and Aβ-metabolism in the early stages of AD, providing a new insight into the underlying pathological mechanism of early AD.

Emerging Role of Neuron-Glia in Neurological Disorders: At a Glance

Based on the diverse physiological influence, the impact of glial cells has become much more evident on neurological illnesses, resulting in the origins of many diseases appearing to be more convoluted than previously happened. Since neurological disorders are often random and unknown, hence the construction of animal models is difficult to build, representing a small fraction of people with a gene mutation. As a result, an immediate necessity is grown to work within in vitro techniques for examining these illnesses. As the scientific community recognizes cell-autonomous contributions to a variety of central nervous system illnesses, therapeutic techniques involving stem cells for treating neurological diseases are gaining traction. The use of stem cells derived from a variety of sources is increasingly being used to replace both neuronal and glial tissue. The brain's energy demands necessitate the reliance of neurons on glial cells in order for it to function properly. Furthermore, glial cells have diverse functions in terms of regulating their own metabolic activities, as well as collaborating with neurons via secreted signaling or guidance molecules, forming a complex network of neuron-glial connections in health and sickness. Emerging data reveals that metabolic changes in glial cells can cause morphological and functional changes in conjunction with neuronal dysfunction under disease situations, highlighting the importance of neuron-glia interactions in the pathophysiology of neurological illnesses. In this context, it is required to improve our understanding of disease mechanisms and create potential novel therapeutics. According to research, synaptic malfunction is one of the features of various mental diseases, and glial cells are acting as key ingredients not only in synapse formation, growth, and plasticity but also in neuroinflammation and synaptic homeostasis which creates critical physiological capacity in the focused sensory system. The goal of this review article is to elaborate state-of-the-art information on a few glial cell types situated in the central nervous system (CNS) and highlight their role in the onset and progression of neurological disorders.

The LINC00623/NAT10 signaling axis promotes pancreatic cancer progression by remodeling ac4C modification of mRNA

BACKGROUND

Although a substantial increase in the survival of patients with other cancers has been observed in recent decades, pancreatic ductal adenocarcinoma (PDAC) remains one of the deadliest diseases. No effective screening approach exists.

METHODS

Differential exosomal long noncoding RNAs (lncRNAs) isolated from the serum of patients with PDAC and healthy individuals were profiled to screen for potential markers in liquid biopsies. The functions of LINC00623 in PDAC cell proliferation, migration and invasion were confirmed through in vivo and in vitro assays. RNA pulldown, RNA immunoprecipitation (RIP) and coimmunoprecipitation (Co-IP) assays and rescue experiments were performed to explore the molecular mechanisms of the LINC00623/NAT10 signaling axis in PDAC progression.

RESULTS

A novel lncRNA, LINC00623, was identified, and its diagnostic value was confirmed, as it could discriminate patients with PDAC from patients with benign pancreatic neoplasms and healthy individuals. Moreover, LINC00623 was shown to promote the tumorigenicity and migratory capacity of PDAC cells in vitro and in vivo. Mechanistically, LINC00623 bound to N-acetyltransferase 10 (NAT10) and blocked its ubiquitination-dependent degradation by recruiting the deubiquitinase USP39. As a key regulator of N4-acetylcytidine (ac4C) modification of mRNA, NAT10 was demonstrated to maintain the stability of oncogenic mRNAs and promote their translation efficiency through ac4C modification.

CONCLUSIONS

Our data revealed the role of LINC00623/NAT10 signaling axis in PDAC progression, showing that it is a potential biomarker and therapeutic target for PDAC.

Engineered extracellular vesicles and their mimetics for cancer immunotherapy

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

Different Sourced Extracellular Vesicles and Their Potential Applications in Clinical Treatments

Extracellular vesicles (EVs) include a heterogeneous group of natural cell-derived nanostructures that are increasingly regarded as promising biotherapeutic agents and drug delivery vehicles in human medicine. Desirable intrinsic properties of EVs including the ability to bypass natural membranous barriers and to deliver their unique biomolecular cargo to specific cell populations position them as fiercely competitive alternatives for currently available cell therapies and artificial drug delivery platforms. EVs with distinct characteristics can be released from various cell types into the extracellular environment as a means of transmitting bioactive components and altering the status of the target cell. Despite the existence of a large number of preclinical studies confirming the therapeutic efficacy of different originated EVs for treating several pathological conditions, in this review, we first provide a brief overview of EV biophysical properties with an emphasis on their intrinsic therapeutic benefits over cell-based therapies and synthetic delivery systems. Next, we describe in detail different EVs derived from distinct cell sources, compare their advantages and disadvantages, and recapitulate their therapeutic effects on various human disorders to highlight the progress made in harnessing EVs for clinical applications. Finally, knowledge gaps and concrete hurdles that currently hinder the clinical translation of EV therapies are debated with a futuristic perspective.

The Emerging Role of the Interaction of Extracellular Vesicle and Autophagy-Novel Insights into Neurological Disorders

Eukaryotic cells release different types of extracellular vesicles (EVs), including exosomes, apoptotic bodies and microvesicles. EVs carry proteins, lipids and nucleic acids specific to cells and cell states. Autophagy is an intracellular degradation process, which, along with EVs, can significantly affect the development and progression of neurological diseases and, therefore, has been the hotspot. Generally, EVs and autophagy are closely associated. EVs and autophagy can interact with each other. On the one hand, the level of autophagy in target cells is closely related to the secretion and transport of EVs. In another, the application of EVs provides a great opportunity for adjuvant treatment of neurological disorders, for which autophagy is an excellent target. EVs can release their cargos into target cells, which, in turn, regulate the autophagic level of target cells through autophagy-related proteins directly and the non-coding RNA, signal transducer and activator of transcription 3 (STAT3), phosphodiesterase enzyme (PDE) 1-B, etc. signaling pathways indirectly, thus regulating the development of related neurological disorders.

Characterization of the microRNA transcriptomes and proteomics of cochlear tissue-derived small extracellular vesicles from mice of different ages after birth

The cochlea is an important sensory organ for both balance and sound perception, and the formation of the cochlea is a complex developmental process. The development of the mouse cochlea begins on embryonic day (E)9 and continues until postnatal day (P)21 when the hearing system is considered mature. Small extracellular vesicles (sEVs), with a diameter ranging from 30 to 200 nm, have been considered a significant medium for information communication in both physiological and pathological processes. However, there are no studies exploring the role of sEVs in the development of the cochlea. Here, we isolated tissue-derived sEVs from the cochleae of FVB mice at P3, P7, P14, and P21 by ultracentrifugation. These sEVs were first characterized by transmission electron microscopy, nanoparticle tracking analysis, and western blotting. Next, we used small RNA-seq and mass spectrometry to characterize the microRNA transcriptomes and proteomes of cochlear sEVs from mice at different ages. Many microRNAs and proteins were discovered to be related to inner ear development, anatomical structure development, and auditory nervous system development. These results all suggest that sEVs exist in the cochlea and are likely to be essential for the normal development of the auditory system. Our findings provide many sEV microRNA and protein targets for future studies of the roles of cochlear sEVs.

Exosome: A novel neurotransmission modulator or non-canonical neurotransmitter?

Neurotransmission is the electrical impulse-triggered propagation of signals between neurons or between neurons and other cell types such as skeletal muscle cells. Recent studies point out the involvement of exosomes, a type of small bilipid layer-enclosed extracellular vesicles, in regulating neurotransmission. Through horizontally transferring proteins, lipids, and nucleic acids, exosomes can modulate synaptic activities rapidly by controlling neurotransmitter release or progressively by regulating neural plasticity including synapse formation, neurite growth & removal, and axon guidance & elongation. In this review, we summarize the similarities and differences between exosomes and synaptic vesicles in their biogenesis, contents, and release. We also highlight the recent progress made in demonstrating the biological roles of exosome in regulating neurotransmission, and propose a modified model of neurotransmission, in which exosomes act as novel neurotransmitters. Lastly, we provide a comprehensive discussion of the enlightenment of the current knowledge on neurotransmission to the future directions of exosome research.

Proteomic screen reveals diverse protein transport between connected neurons in the visual system

Intercellular transfer of toxic proteins between neurons is thought to contribute to neurodegenerative disease, but whether direct interneuronal protein transfer occurs in the healthy brain is not clear. To assess the prevalence and identity of transferred proteins and the cellular specificity of transfer, we biotinylated retinal ganglion cell proteins in vivo and examined biotinylated proteins transported through the rodent visual circuit using microscopy, biochemistry, and mass spectrometry. Electron microscopy demonstrated preferential transfer of biotinylated proteins from retinogeniculate inputs to excitatory lateral geniculate nucleus (LGN) neurons compared with GABAergic neurons. An unbiased mass spectrometry-based screen identified ∼200 transneuronally transported proteins (TNTPs) isolated from the visual cortex. The majority of TNTPs are present in neuronal exosomes, and virally expressed TNTPs, including tau and β-synuclein, were detected in isolated exosomes and postsynaptic neurons. Our data demonstrate transfer of diverse endogenous proteins between neurons in the healthy intact brain and suggest that TNTP transport may be mediated by exosomes.

The promise of exosome applications in treating central nervous system diseases

Exosomes (EXs), a type of extracellular vesicles, are secreted from virtually all types of cells. EXs serve as cell-to-cell communicators by conveying proteins and nucleic acids with regulatory functions. Increasing evidence shows that EXs are implicated in the pathogenesis of central nervous system (CNS) diseases. Moreover, EXs have recently been highlighted as a new promising therapeutic strategy for in vivo delivery of nucleotides and drugs. Studies have revealed that infusion of EXs elicits beneficial effects on the CNS injury animal models. As compared to cell-based therapy, EXs-based therapy for CNS diseases has unique advantages, opening a new path for neurological medicine. In this review, we summarized the current state of knowledge of EXs, the roles and applications of EXs as a viable pathological biomarker, and EX-based therapy for CNS diseases.

Brain exosomes as minuscule information hub for Autism Spectrum Disorder

INTRODUCTION

Autism spectrum disorder (ASD) is a neurodevelopmental disorder initiating in the first three years of life. Early initiation of management therapies can significantly improve the health and quality of life of ASD subjects. Thus, indicating the need for suitable biomarkers for the early identification of ASD. Various biological domains were investigated in the quest for reliable biomarkers. However, most biomarkers are in the preliminary stage, and clinical validation is yet to be defined. Exosome based research gained momentum in various Central Nervous System disorders for biomarker identification. However, the utility and prospect of exosomes in ASD is still underexplored.

AREAS COVERED

In the present review, we summarized the biomarker discovery current status and the future of brain-specific exosomes in understanding pathophysiology and its potential as a biomarker. The studies reviewed herein were identified via systematic search (dated: June 2021) of PubMed using variations related to autism (ASD OR autism OR Autism spectrum disorder) AND exosomes AND/OR biomarkers.

EXPERT OPINION

As exosomess are highly relevant in brain disorders like ASD, direct access to brain tissue for molecular assessment is ethically impossible. Thus investigating the brain-derived exosomes would undoubtedly answer many unsolved aspects of the pathogenesis and provide reliable biomarkers.

The Role of Extracellular Vesicles in the Developing Brain: Current Perspective and Promising Source of Biomarkers and Therapy for Perinatal Brain Injury

This comprehensive review focuses on our current understanding of the proposed physiological and pathological functions of extracellular vesicles (EVs) in the developing brain. Furthermore, since EVs have attracted great interest as potential novel cell-free therapeutics, we discuss advances in the knowledge of stem cell- and astrocyte-derived EVs in relation to their potential for protection and repair following perinatal brain injury. This review identified 13 peer-reviewed studies evaluating the efficacy of EVs in animal models of perinatal brain injury; 12/13 utilized mesenchymal stem cell-derived EVs (MSC-EVs) and 1/13 utilized astrocyte-derived EVs. Animal model, method of EV isolation and size, route, timing, and dose administered varied between studies. Notwithstanding, EV treatment either improved and/or preserved perinatal brain structures both macroscopically and microscopically. Additionally, EV treatment modulated inflammatory responses and improved brain function. Collectively this suggests EVs can ameliorate, or repair damage associated with perinatal brain injury. These findings warrant further investigation to identify the optimal cell numbers, source, and dosage regimens of EVs, including long-term effects on functional outcomes.

Regulation of pyroptosis in cardiovascular pathologies: Role of noncoding RNAs

Cardiovascular disease (CVD) is one of the most important diseases endangering human life. The pathogenesis of CVDs is complex. Pyroptosis, which differs from traditional apoptosis and necrosis, is characterized by cell swelling until membrane rupture, resulting in the release of cell contents and activation of a strong inflammatory response. Recent studies have revealed that inflammation and pyroptosis play important roles in the progression of CVDs. Noncoding RNAs (ncRNAs) are considered promising biomarkers and potential therapeutic targets for the diagnosis and treatment of various diseases, including CVDs. Growing evidence has revealed that ncRNAs can mediate the transcriptional or posttranscriptional regulation of pyroptosis-related genes by participating in the pyroptosis regulatory network. The role and molecular mechanism of pyroptosis-regulating ncRNAs in cardiovascular pathologies are attracting increasing attention. Here, we summarize research progress on pyroptosis and the role of ncRNAs, particularly microRNAs (miRNAs), long ncRNAs (lncRNAs), and circular RNAs (circRNAs), in the regulation of pyroptosis in CVD pathologies. Identifying these disease-related ncRNAs is important for understanding the pathogenesis of CVDs and providing new targets and ideas for their prevention and treatment.

Cerebrospinal Fluid of Patients With Alzheimer's Disease Contains Increased Percentages of Synaptophysin-Bearing Microvesicles

Introduction

In Alzheimer’s disease, the severity of symptoms is linked to a loss of synaptic density and the spread of pathologically hyperphosphorylated tau. The established cerebrospinal fluid markers Aβ, tau and phospho-tau reflect the histopathological hallmarks of Alzheimer’s disease but do not indicate disease progression. Such markers are of special interest, especially for trials of disease modifying drugs. Microvesicles are produced by stressed cells and reflect part of the metabolism of their cells of origin. Therefore, we investigated microvesicles of neuronal origin in cerebrospinal fluid.

Materials and Methods

We used flow cytometry to analyze microvesicles carrying tau, phospho-tau-Thr181, phospho-tau-Ser202Thr205, synaptophysin, and SNAP-25 in the cerebrospinal fluid of 19 patients with Alzheimer’s disease and 15 non-inflammatory neurological disease controls.

Results

The percentages of synaptophysin-bearing microvesicles were significantly higher in the cerebrospinal fluid of patients with Alzheimer’s disease than in the CSF of non-inflammatory neurological disease controls. Tau, phospho-tau-Thr181, phospho-tau-Ser202Thr205, and SNAP-25 did not differ between the groups. The percentages of synaptophysin-bearing vesicles distinguished patients with Alzheimer’s disease from the controls (AUC = 0.81).

Conclusion

The loss of synapses in Alzheimer’s disease may be reflected by synaptophysin-bearing microvesicles in the cerebrospinal fluid. Future studies are needed to investigate the possibility of using these MVs as a marker to determine the activity of Alzheimer’s disease.

Exosomes as drug delivery vehicles and biomarkers for neurological and auditory systems

Exosomes are small extracellular membrane particles that play a crucial role in intracellular signaling. Research shows that exosomes have the potential to be used as biomarkers or drug delivery systems in specific organs, such as the neurological system and the inner ear. Exosomes in neurological and auditory systems release different molecules when under stress versus in healthy states, highlighting their potential use as biomarkers in the identification of diseased states. Studies have suggested that exosomes can be harnessed for drug delivery to hard-to-reach organs, such as cochlear sensory hair cells and the brain due to their ability to cross the blood-labyrinth and blood-brain barriers. In this article, we describe the biogenesis, classification, and characterization methods of exosomes. We then discuss recent studies that indicate their potential usage as biomarkers and drug delivery systems to help treat inner ear and neurological disorders.

The emerging role of exosomes in Alzheimer's disease

Alzheimer's disease (AD), manifested by memory loss and a decline in cognitive functions, is the most prevalent neurodegenerative disease accounting for 60-80 % of dementia cases. But, to-date, there is no effective treatment available to slow or stop the progression of AD. Exosomes are small extracellular vesicles that carry constituents, such as functional messenger RNAs, non-coding RNAs, proteins, lipids, DNA, and other bioactive substances of their source cells. In the brain, exosomes are likely to be sourced by almost all cell types and involve in cell communication to regulate cellular functions. The yet, accumulated evidence on the roles of exosomes and their constituents in the AD pathological process suggests their significance as additional biomarkers and therapeutic targets for AD. This review summarizes the current reported research findings on exosomes roles in the pathogenesis, diagnosis, and treatment of AD.

Regulation of exosome secretion by cellular retinoic acid binding protein 1 contributes to systemic anti-inflammation

Background

Intercellular communications are important for maintaining normal physiological processes. An important intercellular communication is mediated by the exchange of membrane-enclosed extracellular vesicles. Among various vesicles, exosomes can be detected in a wide variety of biological systems, but the regulation and biological implication of exosome secretion/uptake remains largely unclear.

Methods

Cellular retinoic acid (RA) binding protein 1 (Crabp1) knockout (CKO) mice were used for in vivo studies. Extracellular exosomes were monitored in CKO mice and relevant cell cultures including embryonic stem cell (CJ7), macrophage (Raw 264.7) and hippocampal cell (HT22) using Western blot and flow cytometry. Receptor Interacting Protein 140 (RIP140) was depleted by Crispr/Cas9-mediated gene editing. Anti-inflammatory maker was analyzed using qRT-PCR. Clinical relevance was accessed by mining multiple clinical datasets.

Results

This study uncovers Crabp1 as a negative regulator of exosome secretion from neurons. Specifically, RIP140, a pro-inflammatory regulator, can be transferred from neurons, via Crabp1-regulated exosome secretion, into macrophages to promote their inflammatory polarization. Consistently, CKO mice, defected in the negative control of exosome secretion, have significantly elevated RIP140-containing exosomes in their blood and cerebrospinal fluid, and exhibit an increased vulnerability to systemic inflammation. Clinical relevance of this pathway is supported by patients’ data of multiple inflammatory diseases. Further, the action of Crabp1 in regulating exosome secretion involves its ligand and is mediated by its downstream target, the MAPK signaling pathway.

Conclusions

This study presents the first evidence for the regulation of exosome secretion, which mediates intercellular communication, by RA-Crabp1 signaling. This novel mechanism can contribute to the control of systemic inflammation by transferring an inflammatory regulator, RIP140, between cells. This represents a new mechanism of vitamin A action that can modulate the homeostasis of system-wide innate immunity without involving gene regulation.

Emerging roles of extracellular vesicles in COVID-19, a double-edged sword?

The sudden outbreak of SARS‐CoV‐2‐infected disease (COVID‐19), initiated from Wuhan, China, has rapidly grown into a global pandemic. Emerging evidence has implicated extracellular vesicles (EVs), a key intercellular communicator, in the pathogenesis and treatment of COVID‐19. In the pathogenesis of COVID‐19, cells that express ACE2 and CD9 can transfer these viral receptors to other cells via EVs, making recipient cells more susceptible for SARS‐CoV‐2 infection. Once infected, cells release EVs packaged with viral particles that further facilitate viral spreading and immune evasion, aggravating COVID‐19 and its complications. In contrast, EVs derived from stem cells, especially mesenchymal stromal/stem cells, alleviate severe inflammation (cytokine storm) and repair damaged lung cells in COVID‐19 by delivery of anti‐inflammatory molecules. These therapeutic beneficial EVs can also be engineered into drug delivery platforms or vaccines to fight against COVID‐19. Therefore, EVs from diverse sources exhibit distinct effects in regulating viral infection, immune response, and tissue damage/repair, functioning as a double‐edged sword in COVID‐19. Here, we summarize the recent progress in understanding the pathological roles of EVs in COVID‐19. A comprehensive discussion of the therapeutic effects/potentials of EVs is also provided.

Maternal obesity and developmental programming of neuropsychiatric disorders: An inflammatory hypothesis

Maternal obesity is associated with the development of a variety of neuropsychiatric disorders; however, the mechanisms behind this association are not fully understood. Comparison between maternal immune activation and maternal obesity reveals similarities in associated impairments and maternal cytokine profile. Here, we present a summary of recent evidence describing how inflammatory processes contribute towards the development of neuropsychiatric disorders in the offspring of obese mothers. This includes discussion on how maternal cytokine levels, fatty acids and placental inflammation may interact with foetal neurodevelopment through changes to microglial behaviour and epigenetic modification. We also propose an exosome-mediated mechanism for the disruption of brain development under maternal obesity and discuss potential intervention strategies.

Exosomes: A Novel Therapeutic Paradigm for the Treatment of Depression

Extracellular vesicles (EVs) of endocytic origin are known as exosomes. These vesicles are released by cells and are found in biofluids, such as saliva, urine, and plasma. These vesicles are made up of small RNA, DNA, proteins, and play a vital role in many physiological processes. In the central nervous system (CNS), they participate in various physiological processes such as stress of nerve cells, communication between the cells, synaptic plasticity, and neurogenesis. The role of exosomes in depression needs to be explored further. It is known that exosomes can cross the blood brain barrier (BBB), which is made up of glial cells astrocytes. One of the advantages of these vesicles is that they are able to transfer macromolecules like DNA, protein, mRNAs, and miRNAs to recipient cells. This review focuses on the potential role of exosomes in depression and their utilization as a treatment option or diagnostic tool of depression.

Circulating Exosomal Gastric Cancer-Associated Long Noncoding RNA1 as a Biomarker for Early Detection and Monitoring Progression of Gastric Cancer: A Multiphase Study

Questions

What role does circulating exosomal long noncoding RNA-GC1 (lncRNA-GC1) play in gastric cancer (GC), and does lncRNA-GC1 exhibit sufficient diagnostic performance for detecting early-stage GC and for monitoring disease progression?

Findings

In this multiphase study involving 826 participants, including patients with GC, patients with gastric precancerous lesions, and healthy donor individuals, circulating exosomal lncRNA-GC1 served as a noninvasive biomarker for detecting early-stage GC and for monitoring disease progression.

Meaning

For patients with gastric cancer, detection of circulating exosomal lncRNA-GC1 may improve the early diagnostic rate and monitor disease progression.

Importance

The gastric cancer (GC)–associated long noncoding RNA1 (lncRNA-GC1) plays an important role in gastric carcinogenesis. However, exosomal lncRNA-GC1 and its potential role in GC are poorly understood.

Objective

To evaluate the diagnostic value of circulating exosomal lncRNA-GC1 for early detection and monitoring progression of GC.

Design, Setting, and Participants

We performed a multiphase investigation of circulating exosomal lncRNA-GC1 for early detection of GC involving consecutive patients with GC (n = 522), patients with gastric precancerous lesions (n = 85), and healthy donor individuals (HDs; n = 219) from December 2016 to February 2019 at Chinese People’s Liberation Army General Hospital, China. LncRNA-GC1 was measured by reverse transcription–polymerase chain reaction by independent researchers who had no access to patients’ information. Receiver operating characteristic curves were used to calculate diagnostic efficiency in comparison between lncRNA-GC1 and 3 traditional biomarkers (carcinoembryonic antigen [CEA], cancer antigen 72-4 [CA72-4], and CA19-9).

Main Outcomes and Measures

Assessment of diagnostic efficiency on the basis of area under curve (AUC), specificity, and sensitivity.

Results

Of the 826 patients included in the study, 508 were men (61.5%), and the median age of all patients was 60 years (range, 28-82 years). In the test phase, lncRNA-GC1 achieved better diagnostic performance than the standard biomarkers CEA, CA72-4, and CA19-9 (AUC = 0.9033) for distinguishing between the patients with GC and HDs. Additionally, exosomal lncRNA-GC1 levels were significantly higher in culture media from GC cells compared with those of normal gastric epithelial cells (t = 5.310; P = .002). In the verification phase, lncRNA-GC1 retained its diagnostic efficiency in discriminating patients with GC from those with gastric precancerous lesions as well from HDs. Moreover, lncRNA-GC1 exhibited a higher AUC compared with those of CEA, CA72-4, and CA19-9 for early detection of GC with sufficient specificity and sensitivity, especially for patients with GC with negative standard biomarkers. Moreover, the levels of circulating exosomal lncRNA-GC1 were significantly associated with GC from early to advanced stages (HD vs stage I, t = 20.98; P < .001; stage I vs stage II, t = 2.787; P = .006; stage II vs stage III, t = 4.471; P < .001; stage III vs stage IV, t = 1.023; P = .30), independent of pathological grading and Lauren classification (pathological grading: HD vs G1, t = 21.09; P < .001; G1 vs G2, t = 0.3718; P = .71; G2 vs G3, t = 0.3598; P = .72; Lauren classification: t = 24.81; P <.001). In the supplemental phase, the levels of circulating exosomal lncRNA-GC1 were consistent with those in GC tissues and cells and were higher compared with those in normal tissues and cells. Furthermore, the levels of circulating lncRNA-GC1 were unchanged after exosomes were treated with RNase and remained constant after prolonged exposure to room temperature or after repeated freezing and thawing (t = 1.443; P = .39). Total circulating lncRNA-GC1 was nearly all packaged within exosomes rather than a free form in plasma.

Conclusions and Relevence

Circulating exosomal lncRNA-GC1 may serve as a noninvasive biomarker for detecting early-stage GC and for monitoring disease progression. Combining circulating exosomal lncRNA-GC1 detection with endoscopy could improve the early diagnostic rate of GC.

Recent Advances on Extracellular Vesicles in Central Nervous System Diseases

Extracellular vesicles (EVs) are particles released by multiple cells, encapsulated by lipid bilayers and containing a variety of biological materials, including proteins, nucleic acids, lipids and metabolites. With the advancement of separation and characterization methods, EV subtypes and their complex and diverse functions have been recognized. In the central nervous system (CNS), EVs are involved in various physiological and pathological processes, such as regulation of neuronal firing, synaptic plasticity, formation and maintenance of myelin sheath, propagation of neuroinflammation, neuroprotection, and spread and removal of toxic protein aggregates. Activity-dependent alteration of constituents enables EVs to reflect the change of cell and tissue states, and the wide distribution of EVs in biological fluids endows them with potential as diagnostic and prognostic biomarkers for CNS diseases, including neurodegenerative disease, cerebrovascular disease, traumatic brain disease, and brain tumor. Favorable biocompatibility, ability of crossing the blood–brain barrier and protecting contents from degradation, give promising therapeutic effects of EVs, either collected from mesenchymal stem cells culture conditioned media, or designed as drug delivery vehicles loaded with specific agents. In this review, we summarized EVs’ basic biological properties, and mainly focused on their applications in CNS diseases.

Expression and function of Ndel1 during the differentiation of neural stem cells induced by hippocampal exosomesticle

BACKGROUND

In the brain of adult mammals, neural stem cells persist in the subventricular zone of the lateral ventricle and the subgranular zone of the dentate gyrus, which are specialized niches with proliferative capacity. Most neural stem cells are in a quiescent state, but in response to extrinsic stimuli, they can exit from quiescence and become reactivated to produce new neurons, so neural stem cells are considered to be a potential source for cell replacement therapy of many nervous system diseases. We characterized the expression of Ndel1 during the differentiation of neural stem cells induced by hippocampus exosomes, and assessed the effect of Ndel1 on neural stem cells differentiation.

METHODS

Hippocampal exosomes were isolated and extracted, and co-cultured exosomes with neural stem cells. Western blot, flow cytometry, and immunofluorescence analyses were used to analyze expression of neuronal markers. Further, utilizing high-throughput RNA sequencing technology, we found that nudE neurodevelopment protein 1-like 1 was significantly upregulated in exosomes derived from denervated hippocampus, and then characterized its mechanism and function during neural stem cells differentiation by qRT-PCR, western blot, flow cytometry, and immunofluorescence analyses.

RESULTS

Our results revealed that exosomes of denervated hippocampus promoted the differentiation of neural stem cells into neuron. Hence, we identified that nudE neurodevelopment protein 1-like 1 was significantly upregulated and highly expressed in the nervous system. In addition, we found that miR-107-3p may regulate neural stem cell differentiation by targeting Ndel1.

CONCLUSIONS

Our results revealed that deafferentation of the hippocampal exosomes co-cultured with neural stem cells could promote them to differentiate into neurons. Hence, we found that miR-107-3p may regulate neural stem cells differentiation by targeting Ndel1. Importantly, Ndel1 enhanced spatial learning and hippocampal neurogenesis in rats after fimbria fornix transection in vivo. These findings set the stage for a better understanding of neurogenesis, a process that 1 day may inspire new treatments for central nervous system diseases.

Patient-derived iPSC modeling of rare neurodevelopmental disorders: Molecular pathophysiology and prospective therapies

The pathological alterations that manifest during the early embryonic development due to inherited and acquired factors trigger various neurodevelopmental disorders (NDDs). Besides major NDDs, there are several rare NDDs, exhibiting specific characteristics and varying levels of severity triggered due to genetic and epigenetic anomalies. The rarity of subjects, paucity of neural tissues for detailed analysis, and the unavailability of disease-specific animal models have hampered detailed comprehension of rare NDDs, imposing heightened challenge to the medical and scientific community until a decade ago. The generation of functional neurons and glia through directed differentiation protocols for patient-derived iPSCs, CRISPR/Cas9 technology, and 3D brain organoid models have provided an excellent opportunity and vibrant resource for decoding the etiology of brain development for rare NDDs caused due to monogenic as well as polygenic disorders. The present review identifies cellular and molecular phenotypes demonstrated from patient-derived iPSCs and possible therapeutic opportunities identified for these disorders. New insights to reinforce the existing knowledge of the pathophysiology of these disorders and prospective therapeutic applications are discussed.

Caspase-3 Cleaves Extracellular Vesicle Proteins During Auditory Brainstem Development

Sound localization requires extremely precise development of auditory brainstem circuits, the molecular mechanisms of which are largely unknown. We previously demonstrated a novel requirement for non-apoptotic activity of the protease caspase-3 in chick auditory brainstem development. Here, we used mass spectrometry to identify proteolytic substrates of caspase-3 during chick auditory brainstem development. These auditory brainstem caspase-3 substrates were enriched for proteins previously shown to be cleaved by caspase-3, especially in non-apoptotic contexts. Functional annotation analysis revealed that our caspase-3 substrates were also enriched for proteins associated with several protein categories, including proteins found in extracellular vesicles (EVs), membrane-bound nanoparticles that function in intercellular communication. The proteome of EVs isolated from the auditory brainstem was highly enriched for our caspase-3 substrates. Additionally, we identified two caspase-3 substrates with known functions in axon guidance, namely Neural Cell Adhesion Molecule (NCAM) and Neuronal-glial Cell Adhesion Molecule (Ng-CAM), that were found in auditory brainstem EVs and expressed in the auditory pathway alongside cleaved caspase-3. Taken together, these data suggest a novel developmental mechanism whereby caspase-3 influences auditory brainstem circuit formation through the proteolytic cleavage of extracellular vesicle (EV) proteins.

Brain Derived Exosomes Are a Double-Edged Sword in Alzheimer's Disease

Brain derived exosomes (BDEs) are extracellular nanovesicles that are collectively released by all cell lineages of the central nervous system and contain cargo from their original cells. They are emerging as key mediators of communication and waste management among neurons, glial cells and connective tissue during both physiological and pathological conditions in the brain. We review the rapidly growing frontier of BDEs biology in recent years including the involvement of exosomes in neuronal development, maintenance and communication through their multiple signaling functions. Particularly, we highlight the important role of exosomes in Alzheimer's disease (AD), both as a pathogenic agent and as a disease biomarker. Our understanding of such unique nanovesicles may offer not only answers about the (patho) physiological course in AD and associated neurodegenerative diseases but also ideal methods to develop these vesicles as vehicles for drug delivery or as tools to monitor brain diseases in a non-invasive manner because crossing the blood brain barrier is an inherent capability of exosomes. BDEs have potential as biomarkers and as therapeutic tools for AD and related brain disorders in the near future.

An Injectable Nanocomposite Hydrogel for Potential Application of Vascularization and Tissue Repair

In this contribution, an injectable hydrogel was developed with chitosan, gelatin, β-glycerphosphate and Arg-Gly-Asp (RGD) peptide: this hydrogel is liquid in room temperature and rapidly gels at 37 °C; RGD peptide promises better growth microenvironment for various cells, especially endothelial cells (EC), smooth muscle cells (SMC) and mesenchymal stem cells (MSC). Both stromal cell-derived factor-1 (SDF-1) nanoparticle and vascular endothelial growth factor (VEGF) nanoparticles were loaded in the injectable hydrogel to simulate the natural nanoparticles in the extracellular matrix (ECM) to promote angiogenesis. In vitro EC/SMC and MSC/SMC co-culture experiment indicated that the nanocomposite hydrogel accelerated constructing embryonic form of blood vessels, and chick embryo chorioallantoic membrane model demonstrated its ability of improving cells migration and blood vessel regeneration. We injected this nanocomposite hydrogel into rat myocardial infarction (MI) model and the results indicated that the rats heart function recovered better compared control group. We hope this injectable nanocomposite hydrogel may possess wider application in tissue engineering.

The role of non-coding RNAs in neuroprotection and angiogenesis following ischemic stroke

Stroke is the leading cause of death and physical disability worldwide. Non-coding RNAs (ncRNAs) are endogenous molecules that play key roles in the pathophysiology and retrieval processes following ischemic stroke. The potential of ncRNAs, especially microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) in neuroprotection and angiogenesis highlights their potential as targets for therapeutic intervention. In this review, we document the miRNAs and lncRNAs that have been reported to exert regulatory actions in neuroprotective and angiogenic processes through different mechanisms involving their interaction with target coding genes. We believe that exploration of the expression profiles and the possible functions of ncRNAs during the recovery processes will help comprehension of the molecular mechanisms responsible for neuroprotection and angiogenesis, and may also contribute to find biomarkers and targets for future stroke intervention.