Emerging role of neuronal exosomes in the central nervous system

How does exosome cause diabetes?

Exosomes are extracellular vesicles that are widely distributed in multiple cell types and circulating body fluids. They have a specific effect on the target cells by releasing different vesicle contents. They have recently been recognized as important means of intercellular communication, being involved, for example, in the development of diabetes by increasing β-cell apoptosis, activating autoimmunity, and regulating cytokines to affect islet β-cell function and insulin sensitivity. An in-depth study of the role of exosome in the pathogenesis of diabetes may therefore provide a novel means of diagnosing and treating diabetes. In this review, we detail how exosome is involved in the development of diabetes.

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.

Mitigation of Oxidative Stress in Idiopathic Pulmonary Fibrosis Through Exosome-Mediated Therapies

Idiopathic pulmonary fibrosis (IPF) poses a formidable clinical challenge, characterized by the thickening of alveolar septa and the onset of pulmonary fibrosis. The pronounced activation of oxidative stress emerges as a pivotal hallmark of inflammation. Traditional application of exogenous antioxidants proves inadequate in addressing oxidative stress, necessitating exploration into strategies to augment their antioxidant efficacy. Exosomes, nano-sized extracellular vesicles harboring a diverse array of bioactive factors, present as promising carriers with the potential to meet this challenge. Recent attention has been directed towards the clinical applications of exosomes in IPF, fueling the impetus for this comprehensive review. We have compiled fresh insights into the role of exosomes in modulating oxidative stress in IPF and delved into their potential as carriers for regulating endogenous reactive oxygen species generation. This review endeavors to bridge the divide between exosome research and IPF, traversing from bedside to bench. Through the synthesis of recent findings, we propose exosomes as a novel and promising strategy for improving the outcomes of IPF therapy.

Environmental pollutants and exosomes: A new paradigm in environmental health and disease

This study investigates the intricate interplay between environmental pollutants and exosomes, shedding light on a novel paradigm in environmental health and disease. Cellular stress, induced by environmental toxicants or disease, significantly impacts the production and composition of exosomes, crucial mediators of intercellular communication. The heat shock response (HSR) and unfolded protein response (UPR) pathways, activated during cellular stress, profoundly influence exosome generation, cargo sorting, and function, shaping intercellular communication and stress responses. Environmental pollutants, particularly lipophilic ones, directly interact with exosome lipid bilayers, potentially affecting membrane stability, release, and cellular uptake. The study reveals that exposure to environmental contaminants induces significant changes in exosomal proteins, miRNAs, and lipids, impacting cellular function and health. Understanding the impact of environmental pollutants on exosomal cargo holds promise for biomarkers of exposure, enabling non-invasive sample collection and real-time insights into ongoing cellular responses. This research explores the potential of exosomal biomarkers for early detection of health effects, assessing treatment efficacy, and population-wide screening. Overcoming challenges requires advanced isolation techniques, standardized protocols, and machine learning for data analysis. Integration with omics technologies enhances comprehensive molecular analysis, offering a holistic understanding of the complex regulatory network influenced by environmental pollutants. The study underscores the capability of exosomes in circulation as promising biomarkers for assessing environmental exposure and systemic health effects, contributing to advancements in environmental health research and disease prevention.

Engineered exosomes with enhanced stability and delivery efficiency for glioblastoma therapy

Due to the blood-brain barrier (BBB), the application of chemical drugs for glioblastoma treatment is severely limited. Recently, exosomes have been widely applied for drug delivery to the brain. However, the differences in brain targeting efficiency among exosomes derived from different cell sources, as well as the premature drug leakage during circulation, still limit the therapeutic efficacy. Here, we designed a functional oligopeptide-modified exosome loaded with doxorubicin (Pep2-Exos-DOX) for glioblastoma treatment. BV2 mouse microglial cell line was selected as the exosome source due to the favorable BBB penetration. To avoid drug release in the circulation, a redox-response oligopeptide was designed for incorporation into the membranes of exosomes to lock the drug during circulation. The enrichment of the drug in glioblastoma was confirmed. Pharmacodynamic evaluation showed Pep2-Exos-DOX possessed significant anti-cancer activity against glioblastoma as well as relative biosafety. This exosome-based drug delivery system modified with redox-response oligopeptides provides us a novel strategy for brain diseases treatment.

Hypoxia-Induced Neuronal Activity in Glioma Patients Polarizes Microglia by Potentiating RNA m6A Demethylation

PURPOSE

Neuronal activity in the brain has been reported to promote the malignant progression of glioma cells via nonsynaptic paracrine and electrical synaptic integration mechanisms. However, the interaction between neuronal activity and the immune microenvironment in glioblastoma (GBM) remains largely unclear.

EXPERIMENTAL DESIGN

By applying chemogenetic techniques, we enhanced and inhibited neuronal activity in vitro and in a mouse model to study how neuronal activity regulates microglial polarization and affects GBM progression.

RESULTS

We demonstrate that hypoxia drove glioma stem cells (GSC) to produce higher levels of glutamate, which activated local neurons. Neuronal activity promoted GBM progression by facilitating microglial M2 polarization through enriching miR-200c-3p in neuron-derived exosomes, which decreased the expression of the m6A writer zinc finger CCCH-type containing 13 (ZC3H13) in microglia, impairing methylation of dual specificity phosphatase 9 (DUSP9) mRNA. Downregulation of DUSP9 promoted ERK pathway activation, which subsequently induced microglial M2 polarization. In the mouse model, cortical neuronal activation promoted microglial M2 polarization whereas cortical neuronal inhibition decreased microglial M2 polarization in GBM xenografts. miR-200c-3p knockdown in cortical neurons impaired microglial M2 polarization and GBM xenograft growth, even when cortical neurons were activated. Treatment with the anti-seizure medication levetiracetam impaired neuronal activation and subsequently reduced neuron-mediated microglial M2 polarization.

CONCLUSIONS

These findings indicated that hypoxic GSC-induced neuron activation promotes GBM progression by polarizing microglia via the exosomal miR-200c-3p/ZC3H13/DUSP9/p-ERK pathway. Levetiracetam, an antiepileptic drug, blocks the abnormal activation of neurons in GBM and impairs activity-dependent GBM progression. See related commentary by Cui et al., p. 1073.

Extracellular vesicles in Alzheimer's disease

Extracellular vesicles (EVs) are small vesicles released by cells that facilitate cell signaling. They are categorized based on their biogenesis and size. In the context of the central nervous system (CNS), EVs have been extensively studied for their role in both normal physiological functions and diseases like Alzheimer's disease (AD). AD is a neurodegenerative disorder characterized by cognitive decline and neuronal death. EVs have emerged as potential biomarkers for AD due to their involvement in disease progression. Specifically, EVs derived from neurons, astrocytes, and neuron precursor cells exhibit changes in quantity and composition in AD. Neuron-derived EVs have been found to contain key proteins associated with AD pathology, such as amyloid beta (Aß) and tau. Increased levels of Aß in neuron-derived EVs isolated from the plasma have been observed in individuals with AD and mild cognitive impairment, suggesting their potential as early biomarkers. However, the analysis of tau in neuron-derived EVs is still inconclusive. In addition to Aß and tau, neuron-derived EVs also carry other proteins linked to AD, including synaptic proteins. These findings indicate that EVs could serve as biomarkers for AD, particularly for early diagnosis and disease monitoring. However, further research is required to validate their use and explore potential therapeutic applications. To summarize, EVs are small vesicles involved in cell signaling within the CNS. They hold promise as biomarkers for AD, potentially enabling early diagnosis and monitoring of disease progression. Ongoing research aims to refine their use as biomarkers and uncover additional therapeutic applications.

Vesiclepedia 2024: an extracellular vesicles and extracellular particles repository

Vesiclepedia (http://www.microvesicles.org) is a free web-based compendium of DNA, RNA, proteins, lipids and metabolites that are detected or associated with extracellular vesicles (EVs) and extracellular particles (EPs). EVs are membranous vesicles that are secreted ubiquitously by cells from all domains of life from archaea to eukaryotes. In addition to EVs, it was reported recently that EPs like exomeres and supermeres are secreted by some mammalian cells. Both EVs and EPs contain proteins, nucleic acids, lipids and metabolites and has been proposed to be implicated in several key biological functions. Vesiclepedia catalogues proteins, DNA, RNA, lipids and metabolites from both published and unpublished studies. Currently, Vesiclepedia contains data obtained from 3533 EV studies, 50 550 RNA entries, 566 911 protein entries, 3839 lipid entries, 192 metabolite and 167 DNA entries. Quantitative data for 62 822 entries from 47 EV studies is available in Vesiclepedia. The datasets available in Vesiclepedia can be downloaded as tab-delimited files or accessible through the FunRich-based Vesiclepedia plugin.

Elevated SIRT2 of serum exosomes is positively correlated with diagnosis of acute ischemic stroke patients

BACKGROUND

Silent Information Regulator 2 (SIRT2) protein inhibition has been shown to play a neuroprotective role in acute ischemic stroke (AIS) in mice. However, its role in AIS patients has not been fully understood. In this study, we aimed to analyze SIRT2 protein expression in serum exosomes of AIS and non-AIS patients, and evaluate its potential role in diagnosis and prognosis of AIS.

METHODS

Serum exosomes from 75 non-AIS subjects and 75 AIS patients were isolated. The SIRT2 protein levels in exosomes were analyzed using enzyme linked immunosorbent assay (ELISA). The National Institutes of Health Stroke Scale (NIHSS) was used to evaluate the severity of the disease. The modified Rankin Scale (mRS) was employed to assess the functional outcomes of the patients at 3-months following stroke onset.

RESULTS

The SIRT2 protein concentration of serum exosomes were higher in AIS patients than non-AIS patients (p < 0.001). Furthermore, the receiver operative characteristic curve (ROC) demonstrated that higher serum exosome SIRT2 could differentiate AIS patients from non-AIS patients with a sensitivity of 81.3% and a specificity of 75.3%. The area under the curve was 0.838 (95% CI: 0.775, 0.902). Additionally, higher SIRT2 concentration of serum exosomes were associated with NIHSS ≥ 4 (p < 0.001) and mRS ≥ 3 (p = 0.025) in AIS patients. The ROC analysis showed SIRT2 could discriminate stroke with NIHSS ≥ 4 from mild stroke (NIHSS < 4) with a sensitivity of 75.0% and a specificity of 69.6%. The area under the curve was 0.771 (95% CI: 0.661,0.881). Similarly, the test showed SIRT2 could differentiate between AIS patients with mRS ≥ 3 from those with mRS < 3 with a sensitivity of 78.3% and a specificity of 51.9%. The area under the curve was 0.663 (95% CI: 0.531,0.796). The logistic regression analysis revealed that SIRT2 concentration in serum exosomes can independently predict the diagnosis of AIS (odd ratio = 1.394, 95%CI 1.231-1.577, p < 0.001) and higher NIHSS scores (≥ 4) (odd ratio = 1.258, 95%CI 1.084-1.460, p = 0.002). However, it could not independently predict the prognosis of AIS (odd ratio = 1.065, 95%CI 0.983-1.154, p = 0.125).

CONCLUSION

The elevation of SIRT2 in serum exosomes may be a valuable biomarker of AIS, which may be a potential diagnostic tool to facilitate decision making for AIS patients.

Extracellular Vesicles Derived From Neural Stem Cells, Astrocytes, and Microglia as Therapeutics for Easing TBI-Induced Brain Dysfunction

Extracellular vesicles (EVs) derived from neural stem cells (NSC-EVs), astrocytes (ADEVs), and microglia (MDEVs) have neuroregenerative properties. This review discusses the therapeutic efficacy of NSC-EVs, ADEVs, and MDEVs in traumatic brain injury (TBI) models. The translational value and future directions for such EV therapy are also deliberated. Studies have demonstrated that NSC-EV or ADEV therapy can mediate neuroprotective effects and improve motor and cognitive function after TBI. Furthermore, NSC-EVs or ADEVs generated after priming parental cells with growth factors or brain-injury extracts can mediate improved therapeutic benefits. However, the therapeutic effects of naïve MDEVs are yet to be tested rigorously in TBI models. Studies using activated MDEVs have reported both adverse and beneficial effects. NSC-EV, ADEV, or MDEV therapy for TBI is not ready for clinical translation. Rigorous testing of their efficacy for preventing chronic neuroinflammatory cascades and enduring motor and cognitive impairments after treatment in the acute phase of TBI, an exhaustive evaluation of their miRNA or protein cargo, and the effects of delayed EV administration post-TBI for reversing chronic neuroinflammation and enduring brain impairments, are needed. Moreover, the most beneficial route of administration for targeting EVs into different neural cells in the brain after TBI and the efficacy of well-characterized EVs from NSCs, astrocytes, or microglia derived from human pluripotent stem cells need to be evaluated. EV isolation methods for generating clinical-grade EVs must also be developed. Overall, NSC-EVs and ADEVs promise to mitigate TBI-induced brain dysfunction, but additional preclinical studies are needed before their clinical translation.

Comparison of two methods for extracting exosomes from the nucleus accumbens in mice

BACKGROUND

Exosomes bind to and are endocytosed by neurons of various brain regions. Methods for isolating and extracting exosomes from specific brain samples are critical. At present, the most important extractive methods for exosomes are Ultracentrifugation and exosome isolation kit extraction. Both of these extraction methods have applications in neuroscience. We compare these methods to reveal the differences.

METHODS

We sectioned the nucleus accumbens of mice, and isolated exosomes. A culture medium containing exosomes was extracted using ultracentrifugation (UC) and a total exosome isolation kit (TEI). The exosomes were examined using transmission electron microscopy (TEM), measurement regarding the diameter of the exosomes was done, and the thermal allodynia and western blotting analysis were also conducted, respectively.

RESULTS

Transmission electron microscopy observations showed that the ultracentrifugation samples had higher purity and fewer impurities than the kit samples. The results from the two methods were then compared with a number ratio regarding the percentage was not statistically significant. Marker protein tests showed that proteins were expressed under both methods. The thermal allodynia testing observed that the two extraction methods did not affect pain behavior regarding the detection. After the kit extraction method, there were substantial white subjects suspended by PBS.

CONCLUSION

Our study compared the different protocols regarding exosome extraction from the nucleus accumbens and compared the quality of two principal methods for exosome extraction from a culture medium containing exosomes. It was found that the extraction quality of exosomes by ultracentrifugation was better, but the technical difficulty was greater.

Exosomes as biomarkers and therapeutic measures for ischemic stroke

Ischemic stroke (IS) is the leading cause of long-term disability in the world and characterized by high morbidity, recurrence, complications, and mortality. Due to the lack of early diagnostic indicators, limited therapeutic measures and inadequate prognostic indicators, the diagnosis and treatment of IS remains a particular challenge at present. It has recently been reported that exosomes (EXOs) play a significant role in the pathogenesis and treatment of IS. The purpose of this paper is to probe the role of EXOs in diagnostic biomarkers and therapeutic measures for IS and to provide innovative ideas for improving the prognosis of IS.

Applications of Extracellular Vesicles in Nervous System Disorders: An Overview of Recent Advances

Diseases affecting the brain and spinal cord fall under the umbrella term "central nervous system disease". Most medications used to treat or prevent chronic diseases of the central nervous system cannot cross the blood-brain barrier (BBB) and hence cannot reach their intended target. Exosomes facilitate cellular material movement and signal transmission. Exosomes can pass the blood-brain barrier because of their tiny size, high delivery efficiency, minimal immunogenicity, and good biocompatibility. They enter brain endothelial cells via normal endocytosis and reverse endocytosis. Exosome bioengineering may be a method to produce consistent and repeatable isolation for clinical usage. Because of their tiny size, stable composition, non-immunogenicity, non-toxicity, and capacity to carry a wide range of substances, exosomes are indispensable transporters for targeted drug administration. Bioengineering has the potential to improve these aspects of exosomes significantly. Future research into exosome vectors must focus on redesigning the membrane to produce vesicles with targeting abilities to increase exosome targeting. To better understand exosomes and their potential as therapeutic vectors for central nervous system diseases, this article explores their basic biological properties, engineering modifications, and promising applications.

Emerging Roles of Extracellular Vesicles in Alzheimer's Disease: Focus on Synaptic Dysfunction and Vesicle-Neuron Interaction

Alzheimer's disease (AD) is considered by many to be a synaptic failure. Synaptic function is in fact deeply affected in the very early disease phases and recognized as the main cause of AD-related cognitive impairment. While the reciprocal involvement of amyloid beta (Aβ) and tau peptides in these processes is under intense investigation, the crucial role of extracellular vesicles (EVs) released by different brain cells as vehicles for these molecules and as mediators of early synaptic alterations is gaining more and more ground in the field. In this review, we will summarize the current literature on the contribution of EVs derived from distinct brain cells to neuronal alterations and build a working model for EV-mediated propagation of synaptic dysfunction in early AD. A deeper understanding of EV-neuron interaction will provide useful targets for the development of novel therapeutic approaches aimed at hampering AD progression.

Circulating brain-derived extracellular vesicles expressing neuroinflammatory markers are associated with HIV-related neurocognitive impairment

Background

Neurocognitive impairment remains prevalent in people with HIV (PWH) despite long term virological suppression by antiretroviral therapy (ART) regimens. Systemic and neuro-inflammatory processes are suggested to contribute to the complex pathology leading to cognitive impairment in this population, yet the underlying mechanisms remain unresolved. Extracellular vesicles (EVs) play a central role in intracellular communication and have emerged as key modulators of immunological and inflammatory responses. In this report, we examined the impact of EVs in PWH experiencing cognitive deficits to determine their relevance in HIV associated neuropathology.

Methods

EV phenotypes were measured in plasma samples from 108 PWH with either cognitive impairment (CI, n=92) or normal cognition (NC, n=16) by flow cytometry. Matched cerebrospinal fluid (CSF)-derived EVs were similarly profiled from a subgroup of 84 individuals who underwent a lumbar puncture. Peripheral blood mononuclear cells were assayed by flow cytometry to measure monocyte frequencies in a subset of 32 individuals.

Results

Plasma-EVs expressing CD14, CD16, CD192, C195, and GFAP were significantly higher in HIV-infected individuals with cognitive impairment compared to individuals with normal cognition. Increased CSF-EVs expressing GFAP and CD200 were found in the cognitive impairment group compared to the normal cognition group. Frequencies of patrolling monocytes correlated with plasma-EVs expressing CD14, CD66b, MCSF, MAP2, and GFAP. Frequencies of CD195 expression on monocytes correlated positively with plasma-EVs expressing CD41a, CD62P, and CD63. Expression of CD163 on monocytes correlated positively with CSF-EVs expressing GFAP and CD200. Finally, the expression of CD192 on total monocytes correlated with CSF-EVs expressing CD200, CD62P, and CD63.

Conclusions

EVs expressing monocyte activation and neuronal markers associated with HIV associated cognitive impairment, suggesting that distinct EV subsets may serve as novel biomarkers of neuronal injury in HIV infection. Further circulating platelet EV levels were linked to monocyte activation indicating a potential novel interaction in the pathogenesis of HIV-related cognitive impairment.

Molecular actions of exosomes and their theragnostics in colorectal cancer: current findings and limitations

Extracellular vesicles (EVs) are cell-released, membranous structures essential for intercellular communication. The biochemical compositions and physiological impacts of exosomes, lipid-bound, endosomal origin EVs, have been focused on, especially on the tumor-host interactions in a defined tumor microenvironment (TME). Despite recent progress in targeted therapy and cancer immunotherapy in colorectal cancer (CRC), cancer patients still suffer from distal metastasis and tumor relapse, suggesting unmet needs for biomarkers directing therapeutic interventions and predicting treatment responsiveness. As exosomes are indispensable for intercellular communication and high exosome abundance makes them feasible biomarker molecules, this review discusses exosome heterogeneity and how exosomes orchestrate the interplay among tumor cells, cancer stem cells (CSCs) and host cells, including stromal cells, endothelial cells and immunocytes, in the CRC TME. This review also discusses mechanisms for loading exosomal contents and potential exosomal DNA, RNA and protein biomarkers for early CRC detection. Finally, we summarize the diagnostic and therapeutic exosomes in clinical trials. We envision that detecting and targeting cancer-specific exosomes could provide therapeutic advances in developing personalized cancer medicine.

RNA-Binding Proteins as Epigenetic Regulators of Brain Functions and Their Involvement in Neurodegeneration

A central aspect of nervous system development and function is the post-transcriptional regulation of mRNA fate, which implies time- and site-dependent translation, in response to cues originating from cell-to-cell crosstalk. Such events are fundamental for the establishment of brain cell asymmetry, as well as of long-lasting modifications of synapses (long-term potentiation: LTP), responsible for learning, memory, and higher cognitive functions. Post-transcriptional regulation is in turn dependent on RNA-binding proteins that, by recognizing and binding brief RNA sequences, base modifications, or secondary/tertiary structures, are able to control maturation, localization, stability, and translation of the transcripts. Notably, most RBPs contain intrinsically disordered regions (IDRs) that are thought to be involved in the formation of membrane-less structures, probably due to liquid-liquid phase separation (LLPS). Such structures are evidenced as a variety of granules that contain proteins and different classes of RNAs. The other side of the peculiar properties of IDRs is, however, that, under altered cellular conditions, they are also prone to form aggregates, as observed in neurodegeneration. Interestingly, RBPs, as part of both normal and aggregated complexes, are also able to enter extracellular vesicles (EVs), and in doing so, they can also reach cells other than those that produced them.

Exosomal noncoding RNAs in central nervous system diseases: biological functions and potential clinical applications

Central nervous system (CNS) disease is a general term for a series of complex and diverse diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), CNS tumors, stroke, epilepsy, and amyotrophic lateral sclerosis (ALS). Interneuron and neuron-glia cells communicate with each other through their homeostatic microenvironment. Exosomes in the microenvironment have crucial impacts on interneuron and neuron-glia cells by transferring their contents, such as proteins, lipids, and ncRNAs, constituting a novel form of cell-to-cell interaction and communication. Exosomal noncoding RNAs (ncRNAs), including microRNAs (miRNAs), long noncoding RNAs (lncRNAs), circular RNAs (circRNAs), and PIWI-interacting RNAs (piRNAs), regulate physiological functions and maintain CNS homeostasis. Exosomes are regarded as extracellular messengers that transfer ncRNAs between neurons and body fluids due to their ability to cross the blood-brain barrier. This review aims to summarize the current understanding of exosomal ncRNAs in CNS diseases, including prospective diagnostic biomarkers, pathological regulators, therapeutic strategies and clinical applications. We also provide an all-sided discussion of the comparison with some similar CNS diseases and the main limitations and challenges for exosomal ncRNAs in clinical applications.

Long Non-Coding RNAs, Extracellular Vesicles and Inflammation in Alzheimer's Disease

Alzheimer's Disease (AD) has currently no effective treatment; however, preventive measures have the potential to reduce AD risk. Thus, accurate and early prediction of risk is an important strategy to alleviate the AD burden. Neuroinflammation is a major factor prompting the onset of the disease. Inflammation exerts its toxic effect via multiple mechanisms. Amongst others, it is affecting gene expression via modulation of non-coding RNAs (ncRNAs), such as miRNAs. Recent evidence supports that inflammation can also affect long non-coding RNA (lncRNA) expression. While the association between miRNAs and inflammation in AD has been studied, the role of lncRNAs in neurodegenerative diseases has been less explored. In this review, we focus on lncRNAs and inflammation in the context of AD. Furthermore, since plasma-isolated extracellular vesicles (EVs) are increasingly recognized as an effective monitoring strategy for brain pathologies, we have focused on the studies reporting dysregulated lncRNAs in EVs isolated from AD patients and controls. The revised literature shows a positive association between pro-inflammatory lncRNAs and AD. However, the reports evaluating lncRNA alterations in EVs isolated from the plasma of patients and controls, although still limited, confirm the value of specific lncRNAs associated with AD as reliable biomarkers. This is an emerging field that will open new avenues to improve risk prediction and patient stratification, and may lead to the discovery of potential novel therapeutic targets for 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.

Neurovascular Unit-Derived Extracellular Vesicles: From Their Physiopathological Roles to Their Clinical Applications in Acute Brain Injuries

Extracellular vesicles (EVs) form a heterogeneous group of membrane-enclosed structures secreted by all cell types. EVs export encapsulated materials composed of proteins, lipids, and nucleic acids, making them a key mediator in cell–cell communication. In the context of the neurovascular unit (NVU), a tightly interacting multicellular brain complex, EVs play a role in intercellular communication and in maintaining NVU functionality. In addition, NVU-derived EVs can also impact peripheral tissues by crossing the blood–brain barrier (BBB) to reach the blood stream. As such, EVs have been shown to be involved in the physiopathology of numerous neurological diseases. The presence of NVU-released EVs in the systemic circulation offers an opportunity to discover new diagnostic and prognostic markers for those diseases. This review outlines the most recent studies reporting the role of NVU-derived EVs in physiological and pathological mechanisms of the NVU, focusing on neuroinflammation and neurodegenerative diseases. Then, the clinical application of EVs-containing molecules as biomarkers in acute brain injuries, such as stroke and traumatic brain injuries (TBI), is discussed.

Mechanisms and Biomarker Potential of Extracellular Vesicles in Stroke

Simple Summary

A stroke occurs when there is a lack of blood flow to the brain. Stroke injures the brain and can have devastating outcomes depending on the size and location of the brain tissue affected. Currently, there are only a limited number of treatment options for stroke. Extracellular vesicles are small vesicles secreted by cells. Importantly, extracellular vesicles have specific markers indicating the cell they were released from and can pass from the brain into the blood. For these reasons, assessing extracellular vesicles in the blood may create a window into changes occurring in the brain. Assessing changes in extracellular vesicles in the blood during stroke may produce new insight into the cellular changes in the brain causing injury during stroke. This in turn may generate potential targets for the development of future treatments. We summarize what is known about changes in brain-cell-specific extracellular vesicles during stroke and stress the importance of continuing to study these changes.

Abstract

Stoke is a prevalent and devastating neurologic condition with limited options for therapeutic management. Since brain tissue is rarely accessible clinically, peripheral biomarkers for the central nervous system’s (CNS’s) cellular response to stroke may prove critical for increasing our understanding of stroke pathology and elucidating novel therapeutic targets. Extracellular vesicles (EVs) are cell-derived, membrane-enclosed vesicles secreted by all cell types within the CNS that can freely pass the blood-brain barrier (BBB) and contain unique markers and content linked to their cell of origin. These unique qualities make brain-derived EVs novel candidates for non-invasive blood-based biomarkers of both cell specificity and cell physiological state during the progression of stroke and recovery. While studies are continuously emerging that are assessing the therapeutic potential of EVs and profiling EV cargo, a vast minority of these studies link EV content to specific cell types. A better understanding of cell-specific EV release during the acute, subacute, and chronic stages of stroke is needed to further elucidate the cellular processes responsible for stroke pathophysiology. Herein, we outline what is known about EV release from distinct cell types of the CNS during stroke and the potential of these EVs as peripheral biomarkers for cellular function in the CNS during stroke.

Recent advances in diagnostics of neonatal hypoxic ischemic encephalopathy

The prognosis in neonatal hypoxic ischemic encephalopathy (HIE) depends on early differential diagnosis for justified administration of emergency therapeutic hypothermia. The moment of therapy initiation directly affects the long-term neurological outcome: the earlier the commencement, the better the prognosis. This review analyzes recent advances in systems biology that facilitate early differential diagnosis of HIE as a pivotal complement to clinical indicators. We discuss the possibilities of clinical translation for proteomic, metabolomic and extracellular vesicle patterns characteristic of HIE and correlations with severity and prognosis. Identification and use of selective biomarkers of brain damage in neonates during the first hours of life is hindered by systemic effects of hypoxia. Chromatography– mass spectrometry blood tests allow analyzing hundreds and thousands of metabolites in a small biological sample to identify characteristic signatures of brain damage. Clinical use of advanced analytical techniques will facilitate the accurate and timely diagnosis of HIE for enhanced management.

Astrocytes: GABAceptive and GABAergic Cells in the Brain

Astrocytes, the most numerous glial cells in the brain, play an important role in preserving normal neural functions and mediating the pathogenesis of neurological disorders. Recent studies have shown that astrocytes are GABAceptive and GABAergic astrocytes express GABA_A receptors, GABA_B receptors, and GABA transporter proteins to capture and internalize GABA. GABAceptive astrocytes thus influence both inhibitory and excitatory neurotransmission by controlling the levels of extracellular GABA. Furthermore, astrocytes synthesize and release GABA to directly regulate brain functions. In this review, we highlight recent research progresses that support astrocytes as GABAceptive and GABAergic cells. We also summarize the roles of GABAceptive and GABAergic astrocytes that serve as an inhibitory node in the intercellular communication in the brain. Besides, we discuss future directions for further expanding our knowledge on the GABAceptive and GABAergic astrocyte signaling.

Differential Effects of APOE Genotype on MicroRNA Cargo of Cerebrospinal Fluid Extracellular Vesicles in Females With Alzheimer's Disease Compared to Males

Multiple biological factors, including age, sex, and genetics, influence Alzheimer's disease (AD) risk. Of the 6.2 million Americans living with Alzheimer's dementia in 2021, 3.8 million are women and 2.4 million are men. The strongest genetic risk factor for sporadic AD is apolipoprotein E-e4 (APOE-e4). Female APOE-e4 carriers develop AD more frequently than age-matched males and have more brain atrophy and memory loss. Consequently, biomarkers that are sensitive to biological risk factors may improve AD diagnostics and may provide insight into underlying mechanistic changes that could drive disease progression. Here, we have assessed the effects of sex and APOE-e4 on the miRNA cargo of cerebrospinal fluid (CSF) extracellular vesicles (EVs) in AD. We used ultrafiltration (UF) combined with size exclusion chromatography (SEC) to enrich CSF EVs (e.g., Flotillin+). CSF EVs were isolated from female and male AD or controls (CTLs) that were either APOE-e3,4 or -e3,3 positive (n = 7/group, 56 total). MiRNA expression levels were quantified using a custom TaqMan™ array that assayed 190 miRNAs previously found in CSF, including 25 miRNAs that we previously validated as candidate AD biomarkers. We identified changes in the EV miRNA cargo that were affected by both AD and sex. In total, four miRNAs (miR-16-5p, -331-3p, -409-3p, and -454-3p) were significantly increased in AD vs. CTL, independent of sex and APOE-e4 status. Pathway analysis of the predicted gene targets of these four miRNAs with identified pathways was highly relevant to neurodegeneration (e.g., senescence and autophagy). There were also three miRNAs (miR-146b-5p, -150-5p, and -342-3p) that were significantly increased in females vs. males, independent of disease state and APOE-e4 status. We then performed a statistical analysis to assess the effect of APOE genotype in AD within each sex and found that APOE-e4 status affects different subsets of CSF EV miRNAs in females vs. males. Together, this study demonstrates the complexity of the biological factors associated with AD risk and the impact on EV miRNAs, which may contribute to AD pathophysiology.

Extracellular Vesicles: Emerging Roles in Developing Therapeutic Approach and Delivery Tool of Chinese Herbal Medicine for the Treatment of Depressive Disorder

Extracellular vesicles (EVs) are lipid bilayer-delimited particles released by cells, which play an essential role in intercellular communication by delivering cellular components including DNA, RNA, lipids, metabolites, cytoplasm, and cell surface proteins into recipient cells. EVs play a vital role in the pathogenesis of depression by transporting miRNA and effector molecules such as BDNF, IL34. Considering that some herbal therapies exhibit antidepressant effects, EVs might be a practical delivery approach for herbal medicine. Since EVs can cross the blood-brain barrier (BBB), one of the advantages of EV-mediated herbal drug delivery for treating depression with Chinese herbal medicine (CHM) is that EVs can transfer herbal medicine into the brain cells. This review focuses on discussing the roles of EVs in the pathophysiology of depression and outlines the emerging application of EVs in delivering CHM for the treatment of depression.

Adipose stem cell-derived extracellular vesicles ameliorates corticosterone-induced apoptosis in the cortical neurons via inhibition of ER stress

Background

Corticosterone (CORT) can induce neuronal damage in various brain regions, including the cerebral cortex, the region implicated in depression. However, the underlying mechanisms of these CORT-induced effects remain poorly understood. Recently, many studies have suggested that adipose stem cell-derived extracellular vesicles (A-EVs) protect neurons in the brain.

Methods

To investigated neuroprotection effects of A-EVs in the CORT-induced cortical neurons, we cultured cortical neurons from E15 mice for 7 days, and the cultured cortical neurons were pretreated with different numbers (5 × 10⁵–10⁷ per mL) of A-EVs (A-EVs⁵, A-EVs⁶, A-EVs⁷) for 30 min followed by administration of 200 μM CORT for 24 h.

Results

Here, we show that A-EVs exert antiapoptotic effects by inhibiting endoplasmic reticulum (ER) stress in CORT-induced cortical neurons. We found that A-EVs prevented neuronal cell death induced by CORT in cultured cortical neurons. More importantly, we found that CORT exposure in cortical neurons resulted in increased levels of apoptosis-related proteins such as cleaved caspase-3. However, pretreatment with A-EVs rescued the levels of caspase-3. Intriguingly, CORT-induced apoptosis involved upstream activation of ER stress proteins such as GRP78, CHOP and ATF4. However, pretreatment with A-EVs inhibited ER stress-related protein expression.

Conclusion

Our findings reveal that A-EVs exert antiapoptotic effects via inhibition of ER stress in CORT-induced cell death.

Anti-Microbial Activity of Phytocannabinoids and Endocannabinoids in the Light of Their Physiological and Pathophysiological Roles

Antibiotic resistance has become an increasing challenge in the treatment of various infectious diseases, especially those associated with biofilm formation on biotic and abiotic materials. There is an urgent need for new treatment protocols that can also target biofilm-embedded bacteria. Many secondary metabolites of plants possess anti-bacterial activities, and especially the phytocannabinoids of the Cannabis sativa L. varieties have reached a renaissance and attracted much attention for their anti-microbial and anti-biofilm activities at concentrations below the cytotoxic threshold on normal mammalian cells. Accordingly, many synthetic cannabinoids have been designed with the intention to increase the specificity and selectivity of the compounds. The structurally unrelated endocannabinoids have also been found to have anti-microbial and anti-biofilm activities. Recent data suggest for a mutual communication between the endocannabinoid system and the gut microbiota. The present review focuses on the anti-microbial activities of phytocannabinoids and endocannabinoids integrated with some selected issues of their many physiological and pharmacological activities.

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.

Exosomes: A Tool for Bone Tissue Engineering

Mesenchymal stem cells (MSCs) have been repeatedly shown to be a valuable source for cell-based therapy in regenerative medicine, including bony tissue repair. However, engraftment at the injury site is poor. Recently, it has been suggested that MSCs and other cells act through a paracrine signaling mechanism. Exosomes are nanostructures that have been implicated in this process. They carry DNA, RNA, proteins, and lipids and play an important role in cell-to-cell communication directly modulating their target cell at a transcriptional level. In a bone microenvironment, they have been shown to increase osteogenesis and osteogenic differentiation in vivo and in vitro. In the following review, we will discuss the most advanced and significant knowledge of biological functions of exosomes in bone regeneration and their clinical applications in osseous diseases. Impact statement Mesenchymal stem cells have been shown to be a promising tool in bone tissue engineering. Recently, it has been suggested that they secrete exosomes containing messenger RNA, proteins, and lipids, thus acting through paracrine signaling mechanisms. Considering that exosomes are nonteratogenic and have low immunogenic potential, they could potentially replace stem-cell based therapy and thus eradicate the risk of neoplastic transformation associated with cell transplantations in bone regeneration.

Extracellular Vesicles Derived from Young Neural Cultures Attenuate Astrocytic Reactivity In Vitro

Extracellular vesicles (EVs) play an important role in intercellular communication and are involved in both physiological and pathological processes. In the central nervous system (CNS), EVs secreted from different brain cell types exert a sundry of functions, from modulation of astrocytic proliferation and microglial activation to neuronal protection and regeneration. However, the effect of aging on the biological functions of neural EVs is poorly understood. In this work, we studied the biological effects of small EVs (sEVs) isolated from neural cells maintained for 14 or 21 days in vitro (DIV). We found that EVs isolated from 14 DIV cultures reduced the extracellular levels of lactate dehydrogenase (LDH), the expression levels of the astrocytic protein GFAP, and the complexity of astrocyte architecture suggesting a role in lowering the reactivity of astrocytes, while EVs produced by 21 DIV cells did not show any of the above effects. These results in an in vitro model pave the way to evaluate whether similar results occur in vivo and through what mechanisms.

Extracellular Vesicles in Lung Cancer Metastasis and Their Clinical Applications

Extracellular vesicles (EVs) are heterogenous membrane-encapsulated vesicles secreted by every cell into the extracellular environment. EVs carry bioactive molecules, including proteins, lipids, DNA, and different RNA forms, which can be internalized by recipient cells, thus altering their biological characteristics. Given that EVs are commonly found in most body fluids, they have been widely described as mediators of communication in several physiological and pathological processes, including cancer. Moreover, their easy detection in biofluids makes them potentially useful candidates as tumor biomarkers. In this manuscript, we review the current knowledge regarding EVs and non-coding RNAs and their role as drivers of the metastatic process in lung cancer. Furthermore, we present the most recent applications for EVs and non-coding RNAs as cancer therapeutics and their relevance as clinical biomarkers.

Small nucleolar RNAs in plasma extracellular vesicles and their discriminatory power as diagnostic biomarkers of Alzheimer's disease

The clinical diagnosis of Alzheimer's disease, at its early stage, remains a difficult task. Advanced imaging technologies and laboratory assays to detect Aβ peptides Aβ42 and Aβ40, total and phosphorylated tau in CSF provide a set of biomarkers of developing AD brain pathology and facilitate the diagnostic process. The search for biofluid biomarkers, other than in CSF, and the development of biomarker assays have accelerated significantly and now represent the fastest-growing field in AD research. The goal of this study was to determine the differential enrichment of noncoding RNAs (ncRNAs) in plasma-derived extracellular vesicles (EV) of AD patients and Cognitively Normal controls (NC). Using RNA-seq, we profiled four significant classes of ncRNAs: miRNAs, snoRNAs, tRNAs, and piRNAs. We report a significant enrichment of SNORDs - a group of snoRNAs, in AD samples compared to NC. To verify the differential enrichment of two clusters of SNORDs - SNORD115 and SNORD116, localized on human chromosome 15q11-q13, we used plasma samples of an independent group of AD patients and NC. We applied ddPCR technique and identified SNORD115 and SNORD116 with a high discriminatory power to differentiate AD samples from NC. The results of our study present evidence that AD is associated with changes in the enrichment of SNORDs, transcribed from imprinted genomic loci, in plasma EV and provide a rationale to further explore the validity of those SNORDs as plasma biomarkers of AD.

Neurotransmitter-stimulated neuron-derived sEVs have opposite effects on amyloid β-induced neuronal damage

The ratio of excitatory to inhibitory neurotransmitters is essential for maintaining the firing patterns of neural networks, and is strictly regulated within individual neurons and brain regions. Excitatory to inhibitory (E/I) imbalance has been shown to participate in the progression of neurodegenerative diseases, including Alzheimer's disease (AD). Glutamate excitotoxicity and GABAergic neuron dysfunction appear to be key components of the neuronal cell death that takes place in AD. Since extracellular vesicles (EVs) are now explored as an important vehicle in transmitting signals between cells, we hypothesized that the function of neuron-derived small EVs (sEVs) might be regulated by the status of neurotransmitter balance and that sEVs might affect amyloid β (Aβ) toxicity on neurons. This study aimed to reveal the effects of sEVs from unbalanced neurotransmitter-stimulated neurons on Aβ-induced toxicity. We demonstrated the opposite effects of the two groups of sEVs isolated from neurons stimulated by glutamate or GABA on Aβ toxicity in vivo and in vitro. The sEVs released from GABA-treated neurons alleviated Aβ-induced damage, while those released from glutamate-treated neurons aggravated Aβ toxicity. Furthermore, we compared the microRNA (miRNA) composition of sEVs isolated from glutamate/GABA/PBS-treated neurons. Our results showed that glutamate and GABA oppositely regulated miR-132 levels in sEVs, resulting in the opposite destiny of recipient cells challenged with Aβ. Our results indicated that manipulating the function of sEVs by different neurotransmitters may reveal the mechanisms underlying the pathogenesis of AD and provide a promising strategy for AD treatment.

Tissue-derived extracellular vesicles: Research progress from isolation to application

Extracellular vesicles (EVs) are the structures that all cells release into the environment. They are separated by a lipid bilayer and contain the cellular components that release them. To date, most studies have been performed on EVs derived from cell supernatants or different body fluids, while the number of studies on EV isolation directly from tissues is still limited. Studies of EV isolation directly from tissues may provide us with better information. This review summarizes the role of EV in the extracellular matrix, the protocol for isolation of EV in the tissue interstitium, and the application of the protocol in different tissues.

Small Neuron-Derived Extracellular Vesicles from Individuals with Down Syndrome Propagate Tau Pathology in the Wildtype Mouse Brain

Individuals with Down syndrome (DS) exhibit Alzheimer's disease (AD) pathology at a young age, including amyloid plaques and neurofibrillary tangles (NFTs). Tau pathology can spread via extracellular vesicles, such as exosomes. The cargo of neuron-derived small extracellular vesicles (NDEVs) from individuals with DS contains p-Tau at an early age. The goal of the study was to investigate whether NDEVs isolated from the blood of individuals with DS can spread Tau pathology in the brain of wildtype mice. We purified NDEVs from the plasma of patients with DS-AD and controls and injected small quantities using stereotaxic surgery into the dorsal hippocampus of adult wildtype mice. Seeding competent Tau conformers were amplified in vitro from DS-AD NDEVs but not NDEVs from controls. One month or 4 months post-injection, we examined Tau pathology in mouse brains. We found abundant p-Tau immunostaining in the hippocampus of the mice injected with DS-AD NDEVs compared to injections of age-matched control NDEVs. Double labeling with neuronal and glial markers showed that p-Tau staining was largely found in neurons and, to a lesser extent, in glial cells and that p-Tau immunostaining was spreading along the corpus callosum and the medio-lateral axis of the hippocampus. These studies demonstrate that NDEVs from DS-AD patients exhibit Tau seeding capacity and give rise to tangle-like intracellular inclusions.

Exosomes: Structure, Biogenesis, Types and Application in Diagnosis and Gene and Drug Delivery

In recent times, several approaches for targeted gene therapy (GT) had been studied. However, the emergence of extracellular vesicles (EVs) as a shuttle carrying genetic information between cells has gained a lot of interest in scientific communities. Owing to their higher capabilities in dealing with short sequences of nucleic acid (mRNA, miRNA), proteins, recombinant proteins, exosomes, the most popular form of EVs are viewed as reliable biological therapeutic conveyers. They have natural access through every biological membrane and can be employed for site-specific and efficient drug delivery without eliciting any immune responses hence, qualifying as an ideal delivery vehicle. Also, there are many research studies conducted in the last few decades on using exosome-mediated gene therapy into developing an effective therapy with the concept of a higher degree of precision in gene isolation, purification and delivery mechanism loading, delivery and targeting protocols. This review discusses several facets that contribute towards developing an efficient therapeutic regime for gene therapy, highlighting limitations and drawbacks associated with current GT and suggested therapeutic regimes.

Zeb2/Axin2-Enriched BMSC-Derived Exosomes Promote Post-Stroke Functional Recovery by Enhancing Neurogenesis and Neural Plasticity

Exosomes harvested from bone marrow-derived mesenchymal stromal cells (BMSCs) have shown treatment potential in many diseases. In vitro, Zeb2/Axin2 stimulated endogenous neurogenesis, which induced functional recovery after stroke. Here, we investigated whether the Zeb2/Axin2-enriched exosomes harvested from BMSCs transfected with a Zeb2/Axin2 overexpression plasmid would enhance neurological recovery. Compared with the control, both exosome treatments significantly improved functional recovery, and Zeb2/Axin2-enriched exosomes had significantly more improved effects on neurological function, neurogenesis, and neurite remodeling/neuronal dendrite plasticity than the control BMSC exosome treatment in a middle cerebral artery occlusion MCAO rat model. After stimulation with Zeb2/Axin2-enriched BMSC exosomes, the spatial memory and nerve function of MCAO rats showed marked recovery. The number of neurons was increased in the subventricular zone (SVZ), hippocampus, and cortex area, while the expression of nerve growth factors (NGF, BDNF, etc.) was upregulated. In the ischemic boundary zone, Zeb2/Axin2-enriched exosomes promoted synaptic remodeling by increasing the number of synapses and reversed the axonal loss of phosphorylated neurofilament (SMI-31) and synaptophysin (SYN) caused by ischemic injury, thus alleviating axonal demise and promoting synaptic proliferation. In vitro, Zeb2/Axin2-enriched exosomes significantly increased neurite branching and elongation of cultured cortical embryonic rat neurons under oxygen- and glucose-deprived (OGD) conditions. Moreover, Ex-Zeb2/Axin2-enriched exosomes downregulated the protein level of SOX10, endothelin-3/EDNRB, and Wnt/β-catenin expression. In conclusion, exosomes harvested from Ex-Zeb2/Axin2 BMSC could improve post-stroke neuroplasticity and functional recovery in MCAO rats by promoting proliferation and differentiation of neural stem cells. The mechanism may be related to the SOX10, Wnt/β-catenin, and endothelin-3/EDNRB pathways.

Trends in the biological functions and medical applications of extracellular vesicles and analogues

Natural extracellular vesicles (EVs) play important roles in many life processes such as in the intermolecular transfer of substances and genetic information exchanges. Investigating the origins and working mechanisms of natural EVs may provide an understanding of life activities, especially regarding the occurrence and development of diseases. Additionally, due to their vesicular structure, EVs (in small molecules, nucleic acids, proteins, etc.) could act as efficient drug-delivery carriers. Herein, we describe the sources and biological functions of various EVs, summarize the roles of EVs in disease diagnosis and treatment, and review the application of EVs as drug-delivery carriers. We also assess the challenges and perspectives of EVs in biomedical applications.

The Depolarization-Evoked, Ca2+-Dependent Release of Exosomes From Mouse Cortical Nerve Endings: New Insights Into Synaptic Transmission

Whether exosomes can be actively released from presynaptic nerve terminals is a matter of debate. To address the point, mouse cortical synaptosomes were incubated under basal and depolarizing (25 mM KCl-enriched medium) conditions, and extracellular vesicles were isolated from the synaptosomal supernatants to be characterized by dynamic light scattering, transmission electron microscopy, Western blot, and flow cytometry analyses. The structural and biochemical analysis unveiled that supernatants contain vesicles that have the size and the shape of exosomes, which were immunopositive for the exosomal markers TSG101, flotillin-1, CD63, and CD9. The marker content increased upon the exposure of nerve terminals to the high-KCl stimulus, consistent with an active release of the exosomes from the depolarized synaptosomes. High KCl-induced depolarization elicits the Ca2+-dependent exocytosis of glutamate. Interestingly, the depolarization-evoked release of exosomes from cortical synaptosomes also occurred in a Ca2+-dependent fashion, since the TSG101, CD63, and CD9 contents in the exosomal fraction isolated from supernatants of depolarized synaptosomes were significantly reduced when omitting external Ca2+ ions. Differently, (±)-baclofen (10 µM), which significantly reduced the glutamate exocytosis, did not affect the amount of exosomal markers, suggesting that the GABAB-mediated mechanism does not control the exosome release. Our findings suggest that the exposure of synaptosomes to a depolarizing stimulus elicits a presynaptic release of exosomes that occurs in a Ca2+-dependent fashion. The insensitivity to the presynaptic GABAB receptors, however, leaves open the question on whether the release of exosomes could be a druggable target for new therapeutic intervention for the cure of synaptopathies.

Central Nervous System Cell-Derived Exosomes in Neurodegenerative Diseases

Exosomes are a type of extracellular vesicles secreted by almost all kinds of mammalian cells that shuttle "cargo" from one cell to another, indicative of its role in cell-to-cell transportation. Interestingly, exosomes are known to undergo alterations or serve as a pathway in multiple diseases, including neurodegenerative diseases. In the central nervous system (CNS), exosomes originating from neurons or glia cells contribute to or inhibit the progression of CNS-related diseases in special ways. In lieu of this, the current study investigated the effect of CNS cell-derived exosomes on different neurodegenerative diseases.

Cocaine Induces Sex-Associated Changes in Lipid Profiles of Brain Extracellular Vesicles

Cocaine is a highly addictive stimulant with diverse effects on physiology. Recent studies indicate the involvement of extracellular vesicles (EVs) secreted by neural cells in the cocaine addiction process. It is hypothesized that cocaine affects secretion levels of EVs and their cargos, resulting in modulation of synaptic transmission and plasticity related to addiction physiology and pathology. Lipids present in EVs are important for EV formation and for intercellular lipid exchange that may trigger physiological and pathological responses, including neuroplasticity, neurotoxicity, and neuroinflammation. Specific lipids are highly enriched in EVs compared to parent cells, and recent studies suggest the involvement of various lipids in drug-induced synaptic plasticity during the development and maintenance of addiction processes. Therefore, we examined interstitial small EVs isolated from the brain of mice treated with either saline or cocaine, focusing on the effects of cocaine on the lipid composition of EVs. We demonstrate that 12 days of noncontingent repeated cocaine (10 mg/kg) injections to mice, which induce locomotor sensitization, cause lipid composition changes in brain EVs of male mice as compared with saline-injected controls. The most prominent change is the elevation of GD1a ganglioside in brain EVs of males. However, cocaine does not affect the EV lipid profiles of the brain in female mice. Understanding the relationship between lipid composition in EVs and vulnerability to cocaine addiction may provide insight into novel targets for therapies for addiction.

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.

The role of extracellular vesicles in regulating local and systemic inflammation in cardiovascular disease

Extracellular vesicles are heterogeneous structures surrounded by cell membranes and carry complex contents including nucleotides, proteins, and lipids. These proteins include cytokines and chemokines that are important for exaggerating local and systemic inflammation in disease. Extracellular vesicles are mainly categorized as exosomes and micro-vesicles, which are directly shed from the endosomal system or originated from the cell membrane, respectively. By transporting several bioactive molecules to recipient cells and tissues, extracellular vesicles have favorable, neutral, or detrimental impacts on their targets, such as switching cell phenotype, modulating gene expression, and controlling biological pathways such as inflammatory cell recruitment, activation of myeloid cells and cell proliferation. Extracellular vesicles mediate these functions via both autocrine and paracrine signaling. In the cardiovascular system, extracellular vesicles can be secreted by multiple cell types like cardiomyocytes, smooth muscle cells, macrophages, monocytes, fibroblasts, and endothelial cells, and affect functions of cells or tissues in distant organs. These effects involve maintaining homeostasis, regulating inflammation, and triggering pathological process in cardiovascular disease. In this review, we mainly focus on the role of micro-vesicles and exosomes, two important subtypes of extracellular vesicles, in local and systemic inflammation in cardiovascular diseases such as myocardial infarction, atherosclerosis and heart failure. We summarize recent findings and knowledge on the effect of extracellular vesicles in controlling both humoral and cellular immunity, and the therapeutic approaches to harness this knowledge to control exacerbated inflammation in cardiovascular diseases.

Extracellular vesicles (exosomes and ectosomes) play key roles in the pathology of brain diseases

Last century, neurons and glial cells were mostly believed to play distinct functions, relevant for the brain. Progressively, however, it became clear that neurons, astrocytes and microglia co-operate intensely with each other by release/binding of signaling factors, direct surface binding and generation/release of extracellular vesicles, the exosomes and ectosomes, called together vesicles in this abstract. The present review is focused on these vesicles, fundamental in various brain diseases. Their properties are extraordinary. The specificity of their membrane governs their fusion with distinct target cells, variable depending on the state and specificity of their cells of origin and target. Result of vesicle fusion is the discharge of their cargos into the cytoplasm of target cells. Cargos are composed of critical molecules, from proteins (various nature and function) to nucleotides (especially miRNAs), playing critical roles in immune and neurodegenerative diseases. Among immune diseases is multiple sclerosis, affected by extensive dysregulation of co-trafficking neural and glial vesicles, with distinct miRNAs inducing severe or reducing effects. The vesicle-dependent differences between progressive and relapsing-remitting forms of the disease are relevant for clinical developments. In Alzheimer’s disease the vesicles can affect the brain by changing their generation and inducing co-release of effective proteins, such Aβ and tau, from neurons and astrocytes. Specific miRNAs can delay the long-term development of the disease. Upon their traffic through the blood-brainbarrier, vesicles of various origin reach fluids where they are essential for the identification of biomarkers, important for diagnostic and therapeutic innovations, critical for the future of many brain patients.

Size, Shape, and Distribution of Multivesicular Bodies in the Juvenile Rat Somatosensory Cortex: A 3D Electron Microscopy Study

Multivesicular bodies (MVBs) are membrane-bound organelles that belong to the endosomal pathway. They participate in the transport, sorting, storage, recycling, degradation, and release of multiple substances. They interchange cargo with other organelles and participate in their renovation and degradation. We have used focused ion beam milling and scanning electron microscopy (FIB-SEM) to obtain stacks of serial sections from the neuropil of the somatosensory cortex of the juvenile rat. Using dedicated software, we have 3D-reconstructed 1618 MVBs. The mean density of MVBs was 0.21 per cubic micron. They were unequally distributed between dendrites (39.14%), axons (18.16%), and nonsynaptic cell processes (42.70%). About one out of five MVBs (18.16%) were docked on mitochondria, representing the process by which the endosomal pathway participates in mitochondrial maintenance. Other features of MVBs, such as the presence of tubular protrusions (6.66%) or clathrin coats (19.74%) can also be interpreted in functional terms, since both are typical of early endosomes. The sizes of MVBs follow a lognormal distribution, with differences across cortical layers and cellular compartments. The mean volume of dendritic MVBs is more than twice as large as the volume of axonic MVBs. In layer I, they are smaller, on average, than in the other layers.

Stem cells for the treatment of glioblastoma: a 20-year perspective

Glioblastoma, the deadliest form of primary brain tumor, remains a disease without cure. Treatment resistance is in large part attributed to limitations in the delivery and distribution of therapeutic agents. Over the last 20 years, numerous preclinical studies have demonstrated the feasibility and efficacy of stem cells as antiglioma agents, leading to the development of trials to test these therapies in the clinic. In this review we present and analyze these studies, discuss mechanisms underlying their beneficial effect and highlight experimental progress, limitations and the emergence of promising new therapeutic avenues. We hope to increase awareness of the advantages brought by stem cells for the treatment of glioblastoma and inspire further studies that will lead to accelerated implementation of effective therapies.

Glioblastoma is the deadliest and most common form of brain tumor, for which there is no cure. It is very difficult to deliver medicine to the tumor cells, because they spread out widely into the normal brain, and local blood vessels represent a barrier that most medicines cannot cross. It was shown, in many studies over the last 20 years, that stem cells are attracted toward the tumor and that they can deliver many kinds of therapeutic agents directly to brain cancer cells and shrink the tumor. In this review we analyze these studies and present new discoveries that can be used to make stem cell therapies for glioblastoma more effective to prolong the life of patients with brain tumors.

Proteome profiling of neuron-derived exosomes in Alzheimer's disease reveals hemoglobin as a potential biomarker

Alzheimer's disease is a chronic and progressive neurodegenerative disorder, which is the most common cause of dementia worldwide. Although amyloid plaques and neurofibrillary tangles are identified as the hallmarks of the disease, the only valid diagnostic method yet is post-mortem imaging of these molecules in brain sections. Exosome is a type of extracellular vesicles secreted into extracellular space and plays fundamental roles in healthy and pathological conditions, including cell-to-cell communication. In this study, we aimed to investigate the proteomic contents of neuron-derived exosomes (NDEs) from AD patients and healthy controls (HCs) to identify a possible marker for AD diagnosis. We identified alpha-globin, beta-globin, and delta-globin increase in neuron-derived exosomes of AD patients compared to HCs with LC-MS/MS proteomics analysis. Then, we confirmed the high hemoglobin (Hb) level in NDEs of AD patients with ELISA. We found the area under the curve of hemoglobin level as 0.6913 with ROC analysis. Cargo proteins of NDEs may be useful diagnostic biomarker for AD.

The Role of Exosomes in Lysosomal Storage Disorders

Exosomes, small membrane-bound organelles formed from endosomal membranes, represent a heterogenous source of biological and pathological biomarkers capturing the metabolic status of a cell. Exosomal cargo, including lipids, proteins, mRNAs, and miRNAs, can either act as inter-cellular messengers or are shuttled for autophagic/lysosomal degradation. Most cell types in the central nervous system (CNS) release exosomes, which serve as long and short distance communicators between neurons, astrocytes, oligodendrocytes, and microglia. Lysosomal storage disorders are diseases characterized by the accumulation of partially or undigested cellular waste. The exosomal content in these diseases is intrinsic to each individual disorder. Emerging research indicates that lysosomal dysfunction enhances exocytosis, and hence, in lysosomal disorders, exosomal secretion may play a role in disease pathogenesis. Furthermore, the unique properties of exosomes and their ability to carry cargo between adjacent cells and organs, and across the blood-brain barrier, make them attractive candidates for use as therapeutic delivery vehicles. Thus, understanding exosomal content and function may have utility in the treatment of specific lysosomal storage disorders. Since lysosomal dysfunction and the deficiency of at least one lysosomal enzyme, glucocerebrosidase, is associated with the development of parkinsonism, the study and use of exosomes may contribute to an improved understanding of Parkinson disease, potentially leading to new therapeutics.