Increased miR‐124‐3p in microglial exosomes following traumatic brain injury inhibits neuronal inflammation and contributes to neurite outgrowthviatheir transfer into neurons

Engineering small extracellular vesicles: Unlocking the brain's secret passage for central nervous system therapies

Small extracellular vesicles (sEVs), naturally occurring extracellular vesicles, play a pivotal role in intercellular communication and have gained significant attention for their potential in treating central nervous system (CNS) diseases. Due to their ability to cross the blood-brain barrier (BBB) and deliver therapeutic cargo, sEVs are considered a promising vehicle for targeted drug delivery in CNS disorders. Recent advancements in sEVs engineering-such as surface modifications, genetic alterations, and cargo optimization-have substantially enhanced their specificity and therapeutic efficacy. This review examines the relevance of endogenous sEVs in CNS and highlights recent developments in sEVs engineering and cargo optimization. We then discuss strategies for targeting specific brain cells, including neurons, microglia, and endothelial cells. Although clinical applications show promising potential, they remain in early stages, with challenges including large-scale production, precise tracking, standardized preparation, and efficient long-distance targeting. Further research into the cellular mechanisms of sEVs -mediated delivery and the functional differences between sEVs derived from various cell types is crucial for advancing their clinical translation in CNS therapies.

Exosomes: a promising microenvironment modulator for spinal cord injury treatment

Spinal cord injury (SCI) remains a severely disabling disorder that impacts millions globally by causing irreversible damage to the nervous system. Although cell - based therapies have shown notable progress, the post - injury microenvironment presents significant obstacles that hinder the survival and effectiveness of implanted cells, ultimately limiting sustained functional restoration. Exosomes have emerged as a promising cell - free therapeutic alternative due to their stability, low immunogenicity, and ability to carry bioactive molecules such as proteins, microRNAs, and lipids. These vesicles can modulate the injured microenvironment, support neuroprotection, and facilitate repair. This review begins by discussing the pathological alterations that disrupt the microenvironment following SCI. The review then outlines the process of exosome formation and highlights their structural features. Furthermore, the review delves into the diverse cellular sources of exosomes and evaluates their therapeutic relevance in the context of SCI. Special attention is given to the multifaceted roles exosomes play in neuroprotection, such as reinforcing the blood - spinal cord barrier, stimulating axonal regeneration, promoting new blood vessel formation, suppressing programmed cell death in neurons, and modulating inflammatory responses. The synergistic use of exosomes in combination with biomaterials is also explored, with the aim of optimizing their therapeutic potential. Lastly, the review addresses the key obstacles that must be overcome to bring exosome - based treatments into clinical application and offers perspectives on future advancements in this evolving field. In summary, exosomes offer a novel and promising avenue for SCI intervention, holding considerable promise as an alternative to traditional therapeutic approaches.

Resting-State Brain Activity Changes and Their Genetic Correlates in Mild Traumatic Brain Injury

Mild traumatic brain injury (mTBI) often leads to persistent cognitive and emotional symptoms, but the underlying neurobiological mechanisms remain unclear. Although previous studies have reported alterations in resting-state brain activity in mTBI patients, the findings have been inconsistent, and the genetic basis of these changes has not been fully explored. A coordinate-based voxel-wise meta-analysis was conducted to investigate resting-state brain activity changes in mTBI, using nine datasets from 374 patients and 302 healthy controls (HCs). Transcription-neuroimaging association analyses were performed using gene expression data from the Allen Human Brain Atlas (AHBA) to identify genes associated with brain activity alterations. Enrichment analyses were conducted to explore the biological functions of these genes. Compared to HCs, mTBI patients showed increased resting-state brain activity in the left insula and right fusiform gyrus, and decreased activity in the bilateral middle frontal gyrus. Transcription-neuroimaging association analyses identified 840 genes significantly correlated with these brain activity changes. Enrichment analyses revealed 15 biological processes significantly associated with the identified genes, primarily involving chemical synaptic transmission, multicellular organism development, and cell-cell signaling. These genes were also enriched in Pnoc+, Ntsr+, and Cort+ neurons and were expressed predominantly from the late fetal to early adulthood stages. Our findings suggest that alterations in resting-state brain activity in mTBI are linked to specific gene expression patterns, highlighting potential biological pathways involved in mTBI-related brain changes.

Extracellular vesicles in age-related diseases: disease pathogenesis, intervention, and biomarker

Aging is a multifactorial biological process characterized by the irreversible accumulation of molecular damage, leading to an increased risk of age-related diseases. With the global prominent rise in aging populations, elucidating the mechanisms underlying the aging process and developing strategies to combat age-related diseases have become a pressing priority. Extracellular vesicles (EVs) have gained significant attention due to their role in intercellular communication. EVs are known for their ability to deliver biocargoes, such as miRNA, proteins, and lipids, implicating their involvement in disease pathogenesis and intervention. In this review article, we explore the dual role of EVs in age-related diseases: contributing to the pathogenesis of diseases by transferring deleterious molecules, while also offering therapeutic ability by transferring beneficial molecules. We also highlight the application of EVs as biomarkers for early diagnosis of age-related diseases, paving the way for early intervention and precision medicine. Additionally, we discuss how analysing the composition of EVs cargo can provide insights into disease progression. Finally, we address the challenges and future perspectives of EV-based-therapy in clinical translation, including standardization of EVs isolation methods and improving cargo specificity.

Effect of Mechanical Environment Alterations in 3D Stem Cell Culture on the Therapeutic Potential of Extracellular Vesicles

Stem-cell-derived extracellular vesicles (EVs) have emerged as a promising therapeutic option, addressing the limitations of conventional stem cell therapies. However, the variability and poorly defined therapeutic contents of EVs produced under standard 2-dimensional culture conditions present challenges for their clinical application. In this study, we investigated how the therapeutic properties of mesenchymal stem cell (MSC)-derived EVs can be enhanced by culturing MSCs within 3-dimensional hydrogels that have tunable mechanical properties. Our results demonstrate that different mechanical cues from the culture environment can induce specific gene expression changes in MSCs without compromising their inherent characteristics. Furthermore, EVs derived from these MSCs exhibited distinct angiogenic and immunomodulatory activities, which were dependent on the mechanical properties of the hydrogels used. A comprehensive analysis of the cytokines and microRNAs present in the EVs provided additional validation of these findings. By utilizing a noninvasive culture method that eliminates the need for genetic modification or exogenous biochemical supplementation, our approach presents a novel platform for the tailored production of EVs, thereby enhancing their therapeutic potential in regenerative medicine.

M2 microglia-derived small extracellular vesicles modulate NSC fate after ischemic stroke via miR-25-3p/miR-93-5p-TGFBR/PTEN/FOXO3 axis

BACKGROUND

Endogenous neurogenesis could promote stroke recovery. Furthermore, anti-inflammatory phenotypical microglia (M2-microglia) could facilitate Neural Stem Cell (NSC)-mediated neurogenesis following Ischemic Stroke (IS). Nonetheless, the mechanisms through which M2 microglia influence NSC-mediated neurogenesis post-IS remain unclear. On the other hand, M2 microglia-derived small Extracellular Vesicles (M2-sEVs) could exert phenomenal biological effects and play significant roles in cell-to-cell interactions, highlighting their potential involvement in NSC-mediated neurogenesis post-IS, forming the basis of this study.

METHODS

M2-sEVs were first isolated from IL-4-stimulated microglia. For in vivo tests, M2-sEVs were intravenously injected into mice every day for 14 days after transient Middle Cerebral Artery Occlusion (tMCAO). Following that, the infarct volume and neurological function, as well as NSC proliferation in the Subventricular Zone and dentate gyrus, migration, and differentiation in the infarct area, were examined. For in vitro tests, M2-sEVs were administered to NSC subjected to Oxygen-Glucose Deprivation (OGD) and then reoxygenation, after which NSC proliferation and differentiation were assessed. Finally, M2-sEVs were subjected to microRNA sequencing to explore the regulatory mechanisms.

RESULTS

Our findings revealed that M2-sEVs reduced the infarct volume and increased the neurological score in mice post-tMCAO. Furthermore, M2-sEV treatment promoted NSC proliferation and neuronal differentiation both in vivo and in vitro. Additionally, microRNA sequencing revealed miR-93-5p and miR-25-3p enrichment in M2-sEVs. Inhibitors of these miRNAs prevented TGFBR, PTEN, and FOXO3 downregulation in NSC, reversing M2-sEVs' beneficial effects on neurogenesis and sensorimotor recovery.

CONCLUSIONS

M2-sEVs increased NSC proliferation and neuronal differentiation, and protected against IS, at least partially, via delivering miR-25-3p and miR-93-5p to downregulate TGFBR, PTEN, and FOXO3 expression in NSC.

Mesenchymal stem cell exosomes therapy for the treatment of traumatic brain injury: mechanism, progress, challenges and prospects

Traumatic brain injury (TBI) is a heterogeneous disease characterized by brain damage and functional impairment caused by external forces. Under the influence of multiple mechanisms, TBI can cause synaptic dysfunction, protein aggregation, mitochondrial dysfunction, oxidative stress, and neuroinflammatory cascade reactions, resulting in a high disability and mortality rate for patients and a heavy burden on families and society. Exosomes are cell-derived vesicles that encapsulate a variety of molecules, including proteins, lipids, mRNAs, and other small biomolecules. Among these, exosomes derived from mesenchymal stem cells (MSCs) have garnered significant attention owing to their therapeutic potential in the nervous system, offering broad clinical applicability. Recent studies have demonstrated that MSC-derived exosome injections in traumatic brain injury models effectively mitigate local inflammatory damage and promote nerve regeneration following injury. Owing to their small size, challenging replication, ease of preservation, and low immunogenicity, MSC exosomes are emerging as a promising therapeutic strategy for traumatic brain injury. This review explores the pathogenesis of traumatic brain injury, the underlying mechanisms of MSC exosome action, and the potential clinical applications of MSC exosomes in the treatment of traumatic brain injury.

Impact of Microglia-Derived Extracellular Vesicles on Resident Central Nervous System Cell Populations After Acute Brain Injury Under Various External Stimuli Conditions

Acute brain injuries (ABI) caused by various emergencies can lead to structural and functional damage to brain tissue. Common causes include traumatic brain injury, cerebral hemorrhage, ischemic stroke, and heat stroke. Globally, ABI represent a significant portion of neurosurgical cases. Previous studies have emphasized the significant therapeutic potential of stem cell-derived extracellular vesicles (EVs). Recent research indicates that EVs extracted from resident cells in the central nervous system (CNS) also show therapeutic potential following brain injury. Microglia, as innate immune cells of the CNS, respond to changes in the internal environment by altering their phenotype and secreting EVs that impact various CNS cells, including neurons, astrocytes, oligodendrocytes, endothelial cells, neural stem cells (NSCs), and microglia themselves. Notably, under different external stimuli, microglia can either promote neuronal survival, angiogenesis, and myelin regeneration while reducing glial scarring and inflammation, or they can exert opposite effects. This review summarizes and evaluates the current research findings on how microglia-derived EVs influence various CNS cells after ABI under different external stimuli. It analyzes the interaction mechanisms between EVs and resident CNS cells and discusses potential future research directions and clinical applications.

Microglia-derived sEV: Friend or foe in the pathogenesis of cognitive impairment

As immune cells, microglia serve a dual role in cognition. Microglia-derived sEV actively contribute to the development of cognitive impairment by selectively targeting specific cells through various substances such as proteins, RNA, DNA, lipids, and metabolic waste. In recent years, there has been an increasing focus on understanding the pathogenesis and therapeutic potential of sEV. This comprehensive review summarizes the detrimental effects of M1 microglial sEV on pathogenic protein transport, neuroinflammation, disruption of the blood-brain barrier (BBB), neuronal death and synaptic dysfunction in relation to cognitive damage. Additionally, it highlights the beneficial effects of M2 microglia on alleviating cognitive impairment based on evidence from cellular experiments and animal studies. Furthermore, since microglial-secreted sEV can be found in cerebrospinal fluid or cross the BBB into plasma circulation, they play a crucial role in diagnosing cognitive impairment. However, using sEV as biomarkers is still at an experimental stage and requires further clinical validation. Future research should aim to explore the mechanisms underlying microglial involvement in various nervous system disorders to identify novel targets for clinical interventions.

Global status and trends of exosomes in neurodegenerative diseases from 2014 to 2023: a bibliometric and visual analysis

Background

Neurodegenerative diseases (NDs) are chronic and progressive conditions that significantly impact global public health. Recent years have highlighted exosomes as key mechanisms involved in these diseases. This study aims to visualize and analyze the structure and content of exosomes in NDs based on past research to identify new research ideas and directions. Through bibliometric analysis, we assess the current state of research on exosomes in the field of NDs worldwide over the past decade, highlighting significant findings, major research areas, and emerging trends.

Methods

Publications on exosomes in NDs research were obtained from the Web of Science Core Collection (WOSCC) database. Eligible literature was analyzed using Bibliometric R, VOSviewer, and Citespace.

Results

Between 2014 and 2023, 2,393 publications on exosomes in NDs were included in the analysis. The number of relevant publications has been increasing yearly, with China leading in international collaboration, followed by the United States. And China has the largest number of academic scholars as leading and corresponding authors in all the countries, known as the great research society and community. Notable institutions contributing to these publications include Nia, the University of San Francisco California, and Capital Medical University, which rank highly in both publication volume and citations. Dimitrios Kapogiannis is a pivotal figure in the author collaboration network, having produced the highest number of publications (Sato et al., 2011) and amassed 3,921 citations. The journal with the most published articles in this field is The International Journal of Molecular Sciences, which has published 131 articles and received 3,347 citations. A recent analysis of keyword clusters indicates that "Exosome-like liposomes," "Independent mechanisms," and "Therapeutic potential" are emerging research hotspots.

Conclusion

This is the first bibliometric study to provide a comprehensive summary of the research trends and developments regarding exosomes in NDs studies. Future research in this area may explore the role of mesenchymal stromal cells, microRNAs (miRNAs), and targeted drug delivery systems to further investigate the underlying mechanisms and develop new therapeutics.

Metabolic Reprogramming in Primary Microglial Cell and Extracellular Vesicle Triggered by Aβ Exposure

Microglia, key immune cells in the brain, play a pivotal role in brain homeostasis and immune responses. Emerging evidence suggests their critical involvement in Alzheimer's disease (AD) pathogenesis and propagation. The propagation of AD pathology is related to the extracellular matrix of microglia, including extracellular vesicles (EV). Recently, microglia-derived EVs are implicated in inflammatory processes and neuronal death. This study aimed to extensively profile and propose the metabolic role of microglial EVs in AD. Accordingly, we determined the significant alterations of the EV metabolome associated with the metabolites in primary microglial cells. Aβ exposure induced significant metabolic alteration of 39, 18, and 28 metabolites in microglial cells, cultured media, and EVs, respectively. Aβ exposure triggered common alteration of key metabolic pathways between microglial cells and EVs, including purine, amino acid, and fatty acid metabolisms. While most of the common metabolites showed the same directional changes among the microglial system, N-acetyl aspartic acid displayed the opposite directional change in EVs. N-acetyl aspartic acid decreased 2.3-fold and twofold in microglial cells and media, respectively, but increased 3.5-fold in EVs under Aβ exposure. Moreover, mediation analysis proposed key EV metabolites that were directly affected by the metabolic dysregulation of Aβ-exposed microglial cells. The up-regulation of cysteic acid in EVs was mediated by up-regulated IMP in microglial cells. The down-regulation of 1-16:0-lysoPE in EVs was mediated by stearoyl-L-carnitine in microglial cells. Our study sheds new light on the role of microglia and EVs in neurodegenerative diseases, offering promising avenues for future therapeutic interventions.

The roles and therapeutic potential of exosomal non-coding RNAs in microglia-mediated intercellular communication

Exosomes, which are small extracellular vesicles (sEVs), serve as versatile regulators of intercellular communication in the progression of various diseases, including neurological disorders. Among the diverse array of cargo they carry, non-coding RNAs (ncRNAs) play key regulatory roles in various pathophysiological processes. Exosomal ncRNAs derived from distinct cells modulate their reciprocal crosstalk locally or remotely, thereby mediating neurological diseases. Nevertheless, the emerging role of exosomal ncRNAsin microglia-mediated phenotypes remains largely unexplored. This review aims to summarise the biological functions of exosomal ncRNAs and the molecular mechanisms that underlie their impact on microglia-mediated intercellular communication, modulating neuroinflammation and synaptic functions within the landscape of neurological disorders. Furthermore, this review comprehensively described the potential applications of exosomal ncRNAs as diagnostic and prognostic biomarkers, as well as innovative therapeutic targets for the treatment of neurological diseases.

Human-induced pluripotent stem cell-derived neural stem cell exosomes improve blood-brain barrier function after intracerebral hemorrhage by activating astrocytes via PI3K/AKT/MCP-1 axis

JOURNAL/nrgr/04.03/01300535-202502000-00029/figure1/v/2024-05-28T214302Z/r/image-tiff Cerebral edema caused by blood-brain barrier injury after intracerebral hemorrhage is an important factor leading to poor prognosis. Human-induced pluripotent stem cell-derived neural stem cell exosomes (hiPSC-NSC-Exos) have shown potential for brain injury repair in central nervous system diseases. In this study, we explored the impact of hiPSC-NSC-Exos on blood-brain barrier preservation and the underlying mechanism. Our results indicated that intranasal delivery of hiPSC-NSC-Exos mitigated neurological deficits, enhanced blood-brain barrier integrity, and reduced leukocyte infiltration in a mouse model of intracerebral hemorrhage. Additionally, hiPSC-NSC-Exos decreased immune cell infiltration, activated astrocytes, and decreased the secretion of inflammatory cytokines like monocyte chemoattractant protein-1, macrophage inflammatory protein-1α, and tumor necrosis factor-α post-intracerebral hemorrhage, thereby improving the inflammatory microenvironment. RNA sequencing indicated that hiPSC-NSC-Exo activated the PI3K/AKT signaling pathway in astrocytes and decreased monocyte chemoattractant protein-1 secretion, thereby improving blood-brain barrier integrity. Treatment with the PI3K/AKT inhibitor LY294002 or the monocyte chemoattractant protein-1 neutralizing agent C1142 abolished these effects. In summary, our findings suggest that hiPSC-NSC-Exos maintains blood-brain barrier integrity, in part by downregulating monocyte chemoattractant protein-1 secretion through activation of the PI3K/AKT signaling pathway in astrocytes.

The Role of Small Extracellular Vesicles Derived from Glial Cells in the Central Nervous System under both Normal and Pathological Conditions

In recent decades, researchers and clinicians have increasingly focused on glial cell function. One of the primary mechanisms influencing these functions is through extracellular vesicles (EVs), membrane-bound particles released by cells that are essential for intercellular communication. EVs can be broadly categorized into four main types based on their size, origin, and biogenesis: large EVs, small EVs (sEVs), autophagic EVs, and apoptotic bodies. Small EVs (sEVs) are involved in various physiological and pathological processes such as immune responses, angiogenesis, and cellular communication, primarily by transferring proteins, lipids, and nucleic acids to recipient cells. Interactions among glial cells mediated by small EVs can significantly modulate cell polarization and influence glial behavior through miRNA transfer. This communication, facilitated by small EVs in glial cells, is crucial for neuroinflammation, immune responses, and disease progression. This comprehensive review focuses on driven by glial small EVs, highlighting their roles in transporting biomolecules and modulating the functions of recipient cells. Furthermore, we provide an in-depth overview of the specific contributions of small EVs derived from three principal types of glial cells: oligodendrocytes, astrocytes, and microglia.

Stem Cell-Derived Extracellular Vesicle-Mediated Therapeutic Signaling in Spinal Cord Injury

Mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) have emerged as a promising therapeutic strategy for spinal cord injury (SCI). These nanosized vesicles possess unique properties such as low immunogenicity and the ability to cross biological barriers, making them ideal carriers for delivering bioactive molecules to injured tissues. MSC-EVs have been demonstrated to exert multiple beneficial effects in SCI, including reducing inflammation, promoting neuroprotection, and enhancing axonal regeneration. Recent studies have delved into the molecular mechanisms underlying MSC-EV-mediated therapeutic effects. Exosomal microRNAs (miRNAs) have been identified as key regulators of various cellular processes involved in SCI pathogenesis and repair. These miRNAs can influence inflammation, oxidative stress, and apoptosis by modulating gene expression. This review summarized the current state of MSC-EV-based therapies for SCI, highlighting the underlying mechanisms and potential clinical applications. We discussed the challenges and limitations of translating these therapies into clinical practice, such as inconsistent EV production, complex cargo composition, and the need for targeted delivery strategies. Future research should focus on optimizing EV production and characterization, identifying key therapeutic miRNAs, and developing innovative delivery systems to maximize the therapeutic potential of MSC-EVs in SCI.

MicroRNA-specific targets for neuronal plasticity, neurotransmitters, neurotrophic factors, and gut microbes in the pathogenesis and therapeutics of depression

Depression is of great concern because of the huge burden, and it is impacted by various epigenetic modifications, e.g., histone modification, covalent modifications in DNA, and silencing mechanisms of non-coding protein genes, e.g., microRNAs (miRNAs). MiRNAs are a class of endogenous non-coding RNAs. Alternations in specific miRNAs have been observed both in depressive patients and experimental animals. Also, miRNAs are highly expressed in the central nervous system and can be delivered to different tissues via tissue-specific exosomes. However, the mechanism of miRNAs' involvement in the pathological process of depression is not well understood. Therefore, we summarized and discussed the role of miRNAs in depression. Conclusively, miRNAs are involved in the pathology of depression by causing structural and functional changes in synapses, mediating neuronal regeneration, differentiation, and apoptosis, regulating the gut microbes and the expression of various neurotransmitters and BDNF, and mediating inflammatory and immune responses. Moreover, miRNAs can predict the efficacy of antidepressant medications and explain the mechanism of action of antidepressant drugs and aerobic exercise to prevent and assist in treating depression.

Exosomes: new targets for understanding axon guidance in the developing central nervous system

Axon guidance is a key event in neural circuit development that drives the correct targeting of axons to their targets through long distances and unique patterns. Exosomes, extracellular vesicles that are smaller than 100 nm, are secreted by most cell types in the brain. Regulation of cell-cell communication, neuroregeneration, and synapse formation by exosomes have been extensively studied. However, the interaction between exosomes and axon guidance molecules is poorly understood. This review summarizes the relationship between exosomes and canonical and non-canonical guidance cues and hypothesizes a possible model for exosomes mediating axon guidance between cells. The roles of exosomes in axon outgrowth, regeneration, and neurodevelopmental disorders are also reviewed, to discuss exosome-guidance interactions as potential clinical therapeutic targets.

Brain injury biomarkers and applications in neurological diseases

ABSTRACT

Neurological diseases are a major health concern, and brain injury is a typical pathological process in various neurological disorders. Different biomarkers in the blood or the cerebrospinal fluid are associated with specific physiological and pathological processes. They are vital in identifying, diagnosing, and treating brain injuries. In this review, we described biomarkers for neuronal cell body injury (neuron-specific enolase, ubiquitin C-terminal hydrolase-L1, αII-spectrin), axonal injury (neurofilament proteins, tau), astrocyte injury (S100β, glial fibrillary acidic protein), demyelination (myelin basic protein), autoantibodies, and other emerging biomarkers (extracellular vesicles, microRNAs). We aimed to summarize the applications of these biomarkers and their related interests and limits in the diagnosis and prognosis for neurological diseases, including traumatic brain injury, status epilepticus, stroke, Alzheimer's disease, and infection. In addition, a reasonable outlook for brain injury biomarkers as ideal detection tools for neurological diseases is presented.

Regulation of nerve cells and therapeutic potential in central nervous system injury using microglia-derived exosomes

The intercellular communication within the central nervous system (CNS) is of great importance for in maintaining brain function, homeostasis, and CNS regulation. When the equilibrium of CNS is disrupted or injured, microglia are immediately activated and respond to CNS injury. Microglia-derived exosomes are capable of participating in intercellular communication within the CNS by transporting various bioactive substances, including nucleic acids, proteins, lipids, amino acids, and metabolites. Nevertheless, microglia activation is a double-edged sword. Activated microglia can coordinate the neural repair process and, conversely, can amplify tissue injury and impede CNS repair. This work reviewed the roles of exosomes derived from microglia stimulated by different environments (mainly lipopolysaccharide, interleukin-4, and other specific preconditioning) in CNS injury and their possible therapeutic potentials. This work focuses on the regulation of exosomes derived from microglia stimulated by different environments on nerve cells. Meanwhile, we summarized the molecular mechanisms by which the relevant exosomes exert regulatory effects. Exosomes, derived from microglia stimulated by different environments, regulate other nerve cells during the repair of CNS injury, having beneficial or detrimental effects on CNS repair. A comprehensive understanding of the molecular mechanisms underlying their role can provide a robust foundation for the clinical treatment of CNS injury.

Exosomal MiRNA Therapy for Central Nervous System Injury Diseases

Central nervous system diseases include central nervous system injury diseases, neurodegenerative diseases, and other conditions. MicroRNAs (miRNAs) are important regulators of gene expression, with therapeutic potential in modulating genes, pathways, and cells associated with central nervous system injury diseases. This article comprehensively reviews the therapeutic role of exosomal miRNAs in various central nervous system injury diseases, including traumatic brain injury, ischemic stroke, intracerebral hemorrhage, optic nerve injury, and spinal cord injury. This review covers the pathophysiology, animal models, miRNA transfection, administration methods, behavioral tests for evaluating treatment efficacy, and the mechanisms of action of miRNA-based therapies. Finally, this article discusses the future directions of miRNA therapy for central nervous system injury diseases.

Exploring New and Promising Genetic Biomarkers for Evaluating Traumatic Brain Injuries: A Case-Control Study

Traumatic brain injury (TBI) is a common cause of morbidity and death in all age groups, with an estimated 50 million people having brain injury due to trauma each year. Accurate blood-based biomarkers are needed to assist with diagnosis of patients across the spectrum of time and severity. Our objectives were to explore the diagnostic precision of time- and severity- related four blood-based biomarkers: AKT3, GSK-3β, hsa-miR-16-5p, and MALAT-1 for TBI for the purpose of diagnosis, prognosis, and follow-up. 40 samples were recruited as the following: 30 TBI patients and 10 healthy volunteers as controls with matched age and sex. They were divided according to the Glasgow Coma Scale into mild (mTBI), moderate (modTBI), and severe(sTBI) TBI. Blood samples were withdrawn at entry, and after 5 and 30 days, RT-PCR was used for measuring the expression level. The results showed upregulated expression levels of AKT3, hsa-miR-16-5p and significantly downregulated expression levels of GSK-3β in TBI patients compared to controls at all timings measured. mTBI patients showed a higher expression level of hsa-miR-16-5p compared with modTBI, and sTBI patients. MALAT-1 level showed a significant increase in severe cases only. We concluded that AKT3, hsa-miR-16-5p, and GSK-3β are excellent diagnostic biomarkers in TBI patients at initial assessment, as well as at 5 and 30 days following the injury. Moreover, MALAT-1 had good diagnostic value in sTBI patients, and its prognostic value extends to 30 days. GSK-3β was an excellent biomarker for detecting mTBI.

Brain-Derived Exosomal miR-9-5p Induces Ferroptosis in Traumatic Brain Injury-Induced Acute Lung Injury by Targeting Scd1

AIMS

This study aimed to explore the role and underlying mechanisms of brain-derived exosomes in traumatic brain injury-induced acute lung injury (TBI-induced ALI), with a particular focus on the potential regulation of ferroptosis through miRNAs and Scd1.

METHODS

To elucidate TBI-induced ALI, we used a TBI mouse model. Exosomes were isolated from the brains of these mice and characterized using TEM and NTA. LC-MS analysis revealed an increase in the level of ferroptosis in the lung tissues of mice with TBI. Subsequent miRNA and mRNA sequencing revealed the upregulation of miR-9-5p and the downregulation of Scd1 in the pulmonary tissues of these mice. Ferroptosis was assessed by quantifying the levels of ROS, MDA, and Fe2+ and the expression of proteins associated with ferroptosis.

RESULTS

TBI led to the release of exosomes enriched with miR-9-5p, which targeted Scd1 in lung tissue, thereby promoting ferroptosis. Treatment with antagomir 9-5p reduced the level of ALI in TBI mice, indicating that exosomal miR-9-5p plays a significant role in TBI-induced ALI.

CONCLUSION

This study revealed that brain-derived exosomal miR-9-5p mediates ferroptosis in TBI-induced ALI by targeting Scd1. These findings may provide new insights into the complex interplay between TBI and ALI and highlight the potential of miR-9-5p as a target for the development of novel therapeutic strategies.

Blood-derived factors to brain communication in brain diseases

Brain diseases, mainly including acute brain injuries, neurodegenerative diseases, and mental disorders, have posed a significant threat to human health worldwide. Due to the limited regenerative capability and the existence of the blood-brain barrier, the brain was previously thought to be separated from the rest of the body. Currently, various cross-talks between the central nervous system and peripheral organs have been widely described, including the brain-gut axis, the brain-liver axis, the brain-skeletal muscle axis, and the brain-bone axis. Moreover, several lines of evidence indicate that leveraging systemic biology intervention approaches, including but not limited to lifestyle interventions, exercise, diet, blood administration, and peripheral immune responses, have demonstrated a significant influence on the progress and prognosis of brain diseases. The advancement of innovative proteomic and transcriptomic technologies has enriched our understanding of the nuanced interplay between peripheral organs and brain diseases. An array of novel or previously underappreciated blood-derived factors have been identified to play pivotal roles in mediating these communications. In this review, we provide a comprehensive summary of blood-to-brain communication following brain diseases. Special attention is given to the instrumental role of blood-derived signals, positing them as significant contributors to the complex process of brain diseases. The insights presented here aim to bridge the current knowledge gaps and inspire novel therapeutic strategies for brain diseases.

Molecular Targeting of Ischemic Stroke: The Promise of Naïve and Engineered Extracellular Vesicles

Ischemic stroke (IS) remains a leading cause of mortality and long-term disability worldwide, with limited therapeutic options available. Despite the success of early interventions, such as tissue-type plasminogen activator administration and mechanical thrombectomy, many patients continue to experience persistent neurological deficits. The pathophysiology of IS is multifaceted, encompassing excitotoxicity, oxidative and nitrosative stress, inflammation, and blood-brain barrier disruption, all of which contribute to neural cell death, further complicating the treatment of IS. Recently, extracellular vesicles (EVs) secreted naturally by various cell types have emerged as promising therapeutic agents because of their ability to facilitate selective cell-to-cell communication, neuroprotection, and tissue regeneration. Furthermore, engineered EVs, designed to enhance targeted delivery and therapeutic cargo, hold the potential to improve their therapeutic benefits by mitigating neuronal damage and promoting neurogenesis and angiogenesis. This review summarizes the characteristics of EVs, the molecular mechanisms underlying IS pathophysiology, and the emerging role of EVs in IS treatment at the molecular level. This review also explores the recent advancements in EV engineering, including the incorporation of specific proteins, RNAs, or pharmacological agents into EVs to enhance their therapeutic efficacy.

miRNA-124 loaded extracellular vesicles encapsulated within hydrogel matrices for combating chemotherapy-induced neurodegeneration

Chemotherapy-induced neurodegeneration represents a significant challenge in cancer survivorship, manifesting in cognitive impairments that severely affect patients' quality of life. Emerging neuroregenerative therapies offer promise in mitigating these adverse effects, with miRNA-124 playing a pivotal role due to its critical functions in neural differentiation, neurogenesis, and neuroprotection. This review article delves into the innovative approach of using miRNA-124-loaded extracellular vesicles (EVs) encapsulated within hydrogel matrices as a targeted strategy for combating chemotherapy-induced neurodegeneration. We explore the biological underpinnings of miR-124 in neuroregeneration, detailing its mechanisms of action and therapeutic potential. The article further examines the roles and advantages of EVs as natural delivery systems for miRNAs and the application of hydrogel matrices in creating a sustained release environment conducive to neural tissue regeneration. By integrating these advanced materials and biological agents, we highlight a synergistic therapeutic strategy that leverages the bioactive properties of miR-124, the targeting capabilities of EVs, and the supportive framework of hydrogels. Preclinical studies and potential pathways to clinical translation are discussed, alongside the challenges, ethical considerations, and future directions in the field. This comprehensive review underscores the transformative potential of miR-124-loaded EVs in hydrogel matrices, offering insights into their development as a novel and integrative approach for addressing the complexities of chemotherapy-induced neurodegeneration.

The role of autophagy in brain health and disease: Insights into exosome and autophagy interactions

Effective management of cellular components is essential for maintaining brain health, and studies have identified several crucial biological processes in the brain. Among these, autophagy and the role of exosomes in cellular communication are critical for brain health and disease. The interaction between autophagy and exosomes in the nervous system, as well as their contributions to brain damage, have garnered significant attention. This review summarizes that exosomes and their cargoes have been implicated in the autophagy process in the pathophysiology of nervous system diseases. Furthermore, the onset and progression of neurological disorders may be affected by autophagy regulation of the secretion and release of exosomes. These findings may provide new insights into the potential mechanism by which autophagy mediates different exosome secretion and release, as well as the valuable biomedical applications of exosomes in the prevention and treatment of various brain diseases by targeting autophagy.

The Yin and Yang of Microglia-Derived Extracellular Vesicles in CNS Injury and Diseases

Microglia, the resident immune cells of the central nervous system (CNS), play a crucial role in maintaining neural homeostasis but can also contribute to disease and injury when this state is disrupted or conversely play a pivotal role in neurorepair. One way that microglia exert their effects is through the secretion of small vesicles, microglia-derived exosomes (MGEVs). Exosomes facilitate intercellular communication through transported cargoes of proteins, lipids, RNA, and other bioactive molecules that can alter the behavior of the cells that internalize them. Under normal physiological conditions, MGEVs are essential to homeostasis, whereas the dysregulation of their production and/or alterations in their cargoes have been implicated in the pathogenesis of numerous neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), spinal cord injury (SCI), and traumatic brain injury (TBI). In contrast, MGEVs may also offer therapeutic potential by reversing inflammation or being amenable to engineering for the delivery of beneficial biologics or drugs. The effects of MGEVs are determined by the phenotypic state of the parent microglia. Exosomes from anti-inflammatory or pro-regenerative microglia support neurorepair and cell survival by delivering neurotrophic factors, anti-inflammatory mediators, and molecular chaperones. Further, MGEVs can also deliver components like mitochondrial DNA (mtDNA) and proteins to damaged neurons to enhance cellular metabolism and resilience. MGEVs derived from pro-inflammatory microglia can have detrimental effects on neural health. Their cargo often contains pro-inflammatory cytokines, molecules involved in oxidative stress, and neurotoxic proteins, which can exacerbate neuroinflammation, contribute to neuronal damage, and impair synaptic function, hindering neurorepair processes. The role of MGEVs in neurodegeneration and injury-whether beneficial or harmful-largely depends on how they modulate inflammation through the pro- and anti-inflammatory factors in their cargo, including cytokines and microRNAs. In addition, through the propagation of pathological proteins, such as amyloid-beta and alpha-synuclein, MGEVs can also contribute to disease progression in disorders such as AD and PD, or by the transfer of apoptotic or necrotic factors, they can induce neuron toxicity or trigger glial scarring during neurological injury. In this review, we have provided a comprehensive and up-to-date understanding of the molecular mechanisms underlying the multifaceted role of MGEVs in neurological injury and disease. In particular, the role that specific exosome cargoes play in various pathological conditions, either in disease progression or recovery, will be discussed. The therapeutic potential of MGEVs has been highlighted including potential engineering methodologies that have been employed to alter their cargoes or cell-selective targeting. Understanding the factors that influence the balance between beneficial and detrimental exosome signaling in the CNS is crucial for developing new therapeutic strategies for neurodegenerative diseases and neurotrauma.

Brain incoming call from glia during neuroinflammation: Roles of extracellular vesicles

The functionality of the central nervous system (CNS) relies on the connection, integration, and the exchange of information among neural cells. The crosstalk among glial cells and neurons is pivotal for a series of neural functions, such as development of the nervous system, electric conduction, synaptic transmission, neural circuit establishment, and brain homeostasis. Glial cells are crucial players in the maintenance of brain functionality in physiological and disease conditions. Neuroinflammation is a common pathological process in various brain disorders, such as neurodegenerative diseases, and infections. Glial cells, including astrocytes, microglia, and oligodendrocytes, are the main mediators of neuroinflammation, as they can sense and respond to brain insults by releasing pro-inflammatory or anti-inflammatory factors. Recent evidence indicates that extracellular vesicles (EVs) are pivotal players in the intercellular communication that underlies physiological and pathological processes. In particular, glia-derived EVs play relevant roles in modulating neuroinflammation, either by promoting or inhibiting the activation of glial cells and neurons, or by facilitating the clearance or propagation of pathogenic proteins. The involvement of EVs in neurodegenerative diseases such as Alzheimer's Disease (AD), Parkinson's Disease (PD), Huntington's Disease (HD), and Multiple Sclerosis (MS)- which share hallmarks such as neuroinflammation and oxidative stress to DNA damage, alterations in neurotrophin levels, mitochondrial impairment, and altered protein dynamics- will be dissected, showing how EVs act as pivotal cell-cell mediators of toxic stimuli, thereby propagating degeneration and cell death signaling. Thus, this review focuses on the EVs secreted by microglia, astrocytes, oligodendrocytes and in neuroinflammatory conditions, emphasizing on their effects on neurons and on central nervous system functions, considering both their beneficial and detrimental effects.

The regulatory role of miR-21 in ferroptosis by targeting FTH1 and the contribution of microglia-derived miR-21 in exosomes to arsenic-induced neuronal ferroptosis

Arsenic is recognized as a hazardous environmental toxicant strongly associated with neurological damage, but the mechanism is ambiguous. Neuronal cell death is one of the mechanisms of arsenic-induced neurological injury. Ferroptosis is involved in the pathophysiological process of many neurological diseases, however, the role and regulatory mechanism of ferroptosis in nerve injury under arsenic exposure remains uncovered. Our findings confirmed the role of ferroptosis in arsenic-induced learning and memory disorder and revealed miR-21 played a regulatory role in neuronal ferroptosis. Further study discovered that miR-21 regulated neuronal ferroptosis by targeting at FTH1, a finding which has not been documented before. We also found an extra increase of ferroptosis in neuronal cells conditionally cultured by medium collected from arsenic-exposed microglial cells when compared with neuronal cells directly exposed to the same dose of arsenic. Moreover, microglia-derived exosomes removal or miR-21 knockdown in microglia inhibited neuronal ferroptosis, suggesting the role of intercellular communication in the promotion of neuronal ferroptosis. In summary, our findings highlighted the regulatory role of miR-21 in ferroptosis and the contribution of microglia-derived miR-21 in exosomes to arsenic-induced neuronal ferroptosis.

M2 Microglia-derived Exosomes Promote Spinal Cord Injury Recovery in Mice by Alleviating A1 Astrocyte Activation

M2 microglia transplantation has previously demonstrated beneficial effects on spinal cord injury (SCI) by regulating neuroinflammation and enhancing neuronal survival. Exosomes (EXOs), secreted by almost all cell types, embody partial functions and properties of their parent cells. However, the effect of M2 microglia-derived EXOs (M2-EXOs) on SCI recovery and the underlying molecular mechanisms remain unclear. In this study, we isolated M2-EXOs and intravenously introduced them into mice with SCI. Considering the reciprocal communication between microglia and astroglia in both healthy and injured central nervous systems (CNSs), we subsequently focused on the influence of M2-EXOs on astrocyte phenotype regulation. Our findings indicated that M2-EXOs promoted neuron survival and axon preservation, reduced the lesion area, inhibited A1 astrocyte activation, and improved motor function recovery in SCI mice. Moreover, they inhibited the nuclear translocation of p65 and the activation of the NF-κB signalling pathway in A1 astrocytes. Therefore, our research suggests that M2-EXOs mitigate the activation of neurotoxic A1 astrocytes by inhibiting the NF-κB signalling pathway, thereby improving spinal tissue preservation and motor function recovery following SCI. This positions M2-EXOs as a promising therapeutic strategy for SCI.

Effects of ADSC-Derived Exosome LRRC75A-AS1 on Anti-inflammatory Function After SCI

Spinal cord injury (SCI) is a highly debilitating disorder of the central nervous system that can severely impact an affected patient's quality of life. This study aimed to examine how adipose-derived mesenchymal stem cell exosomes (ADSC-exos) can be used to treat spinal cord injury. We analysed differentially expressed mRNAs in SCI using bioinformatics data, gene expression profiles in inflammatory cell models, RT-qPCR and WB. Apoptosis was detected with flow cytometry. Starbase provides the control mechanism for FDFT1. Target interactions were detected with dual-luciferase reporter and RIP assays. Exosomes were isolated from adipose tissue-derived mesenchymal stem cells and subsequently characterized with western blot analysis, transmission electron microscopy and nanoparticle tracking analysis. By analysing the GSE102964 database, we found that FDFT1 was significantly downregulated as SCI progressed. Overexpression of FDFT1 can significantly reverse the inflammatory response and apoptosis of BV2 cells induced by hemin. Mechanically, ADSC-exos can affect the expression of FDFT1 through the ceRNA mechanism mediated by LRRC75A-AS1 and in an RBP-dependent manner mediated by IGF2BP2. The overexpression of LRRC75A-AS1 significantly enhances BV2 apoptosis and can be reversed by FDFT1 knockdown. ADSC-exos LRRC75A-AS1 inhibits inflammation and reduces SCI by increasing the expression and stability of FDFT1 mRNA in a ceRNA and RBP-dependent manner.

Exosomes: A Cellular Communication Medium That Has Multiple Effects On Brain Diseases

Exosomes, as membranous vesicles generated by multiple cell types and secreted to extracellular space, play a crucial role in a range of brain injury-related brain disorders by transporting diverse proteins, RNA, DNA fragments, and other functional substances. The nervous system's pathogenic mechanisms are complicated, involving pathological processes like as inflammation, apoptosis, oxidative stress, and autophagy, all of which result in blood-brain barrier damage, cognitive impairment, and even loss of normal motor function. Exosomes have been linked to the incidence and progression of brain disorders in recent research. As a result, a thorough knowledge of the interaction between exosomes and brain diseases may lead to the development of more effective therapeutic techniques that may be implemented in the clinic. The potential role of exosomes in brain diseases and the crosstalk between exosomes and other pathogenic processes were discussed in this paper. Simultaneously, we noted the delicate events in which exosomes as a media allow the brain to communicate with other tissues and organs in physiology and disease, and compiled a list of natural compounds that modulate exosomes, in order to further improve our understanding of exosomes and propose new ideas for treating brain disorders.

Exosomes derived from microglia overexpressing miR-124-3p alleviate neuronal endoplasmic reticulum stress damage after repetitive mild traumatic brain injury

JOURNAL/nrgr/04.03/01300535-202409000-00033/figure1/v/2024-01-16T170235Z/r/image-tiff We previously reported that miR-124-3p is markedly upregulated in microglia-derived exosomes following repetitive mild traumatic brain injury. However, its impact on neuronal endoplasmic reticulum stress following repetitive mild traumatic brain injury remains unclear. In this study, we first used an HT22 scratch injury model to mimic traumatic brain injury, then co-cultured the HT22 cells with BV2 microglia expressing high levels of miR-124-3p. We found that exosomes containing high levels of miR-124-3p attenuated apoptosis and endoplasmic reticulum stress. Furthermore, luciferase reporter assay analysis confirmed that miR-124-3p bound specifically to the endoplasmic reticulum stress-related protein IRE1α, while an IRE1α functional salvage experiment confirmed that miR-124-3p targeted IRE1α and reduced its expression, thereby inhibiting endoplasmic reticulum stress in injured neurons. Finally, we delivered microglia-derived exosomes containing miR-124-3p intranasally to a mouse model of repetitive mild traumatic brain injury and found that endoplasmic reticulum stress and apoptosis levels in hippocampal neurons were significantly reduced. These findings suggest that, after repetitive mild traumatic brain injury, miR-124-3 can be transferred from microglia-derived exosomes to injured neurons, where it exerts a neuroprotective effect by inhibiting endoplasmic reticulum stress. Therefore, microglia-derived exosomes containing miR-124-3p may represent a novel therapeutic strategy for repetitive mild traumatic brain injury.

Extracellular vesicle therapy in neurological disorders

Extracellular vesicles (EVs) are vital for cell-to-cell communication, transferring proteins, lipids, and nucleic acids in various physiological and pathological processes. They play crucial roles in immune modulation and tissue regeneration but are also involved in pathogenic conditions like inflammation and degenerative disorders. EVs have heterogeneous populations and cargo, with numerous subpopulations currently under investigations. EV therapy shows promise in stimulating tissue repair and serving as a drug delivery vehicle, offering advantages over cell therapy, such as ease of engineering and minimal risk of tumorigenesis. However, challenges remain, including inconsistent nomenclature, complex characterization, and underdeveloped large-scale production protocols. This review highlights the recent advances and significance of EVs heterogeneity, emphasizing the need for a better understanding of their roles in disease pathologies to develop tailored EV therapies for clinical applications in neurological disorders.

Dental Stem Cell-Derived Exosomes: A Review of Their Isolation, Classification, Functions, and Mechanisms

The scientific field concerned with the study of regeneration has developed rapidly in recent years. Stem cell therapy is a highly promising therapeutic modality for repairing tissue defects; however, several limitations exist, such as cytotoxicity, potential immune rejection, and ethical issues. Exosomes secreted by stem cells are cell-specific secreted vesicles that play a regulatory role in many biological functions in the human body; they not only have a series of functional roles of stem cells and exert the expected therapeutic effects, but they can also overcome the mass limitations of stem cells and are thus considered in the research as an alternative treatment strategy for stem cells. Since dental stem cell-derived exosomes (DSC-Exos) are easy to acquire and present modulating effects in several fields, including neurovascular regeneration and craniofacial soft and hard tissue regeneration processes, they are served as an emerging cell-free therapeutic strategy in various systematic diseases. There is a growing body of research on various types of DSC-Exos; however, they lack systematic elaboration and tabular summarization. Therefore, this review presents the isolation, characterization, and phenotypes of DSC-Exos and focuses on their current status of functions and mechanisms, as well as the multiple challenges prior to clinical applications.

The role of exosome-shuttled miRNAs in heavy metal-induced peripheral tissues and neuroinflammation in Alzheimer's disease

Heavy metal-induced neuroinflammation is a significant pathophysiologic mechanism in Alzheimer's disease (AD). Microglia-mediated neuroinflammation plays a crucial role in the pathogenesis of AD. Multiple miRNAs are differentially expressed in peripheral tissues after heavy metal exposure, and increasing evidence suggests that they are involved in AD progression by regulating microglial homeostasis. Exosomes, which are capable of loading miRNAs and crossing the bloodbrain barrier, serve as mediators of communication between peripheral tissues and the brain. In this review, we summarize the current evidence on the link between miRNAs in peripheral tissues and neuroinflammation in AD after heavy metal exposure and propose a role for miRNAs in the microglial neurodegenerative phenotype (MGnD) of AD. This study will help to elucidate the link between peripheral tissue damage and MGnD-mediated neuroinflammation in AD after heavy metal exposure. Additionally, we summarize the regulatory effects of natural compounds on peripheral tissue-derived miRNAs, which could be potential therapeutic targets for natural compounds to regulate peripheral tissue-derived exosomal miRNAs to ameliorate heavy metal-induced MGnD-mediated neuroinflammation in patients with AD after heavy metal exposure.

Profiling of microglial-originated microvesicles to unearthing their lurking potential as potent foreseeable biomarkers for the diagnosis of Alzheimer's disease: A systematic review

BACKGROUND

Alzheimer's Disease is a neurodegenerative disease characterized by accumulation of phosphorylated tau and amyloid deposits within the brain tissues in the elderly population. Numerous studies established that amassment of these toxic accretions within the brain tissues initiates neuronal demise and synaptic impairment which becomes the underlying basis for memory loss and cognitive abnormalities in these patients.

HYPOTHESIS

Hypoxia, oxidative stress, and inflammation are commonly encountered perils in the neuronal milieu that derail the neuron-synapse interactions and maneuver them to undergo apoptosis. A spinoff from neuronal desecration is microglial activation which forms a cardinal role in mounting innate immune defenses for warding off and reversing off toxic stimulus encountered.

RESULTS

A potential ramification of microglial activation in this context is assembly, processing and exuding of micro-vesicles into the extracellular space. These micro-vesicles will be packaged with amyloid and tau deposits which accumulate intracellularly within microglial cells secondary to their professional scavenging function. These microglial MVs are prone to seed tau and amyloid beta into the surrounding neuron-synapse framework, thus are implicated in spreading the disease pathology in AD.

CONCLUSIONS

Therefore, these MVs can be considered as an omen for disease initiation, progression, monitoring as well gauging the treatment response in the clinical AD cohorts. We speculate future research studies to unmask the dormant potential of these microglial MVs as reliable markers for diagnosis, evaluating the disease progression as well as treatment in AD. This will open the door for early diagnosis of AD so as to prioritize management and optimize clinical outcomes..

Exploration of the Key Genes Involved in Non-alcoholic Fatty Liver Disease and Possible MicroRNA Therapeutic Targets

Background

MicroRNAs (miRNAs) are promising therapeutic agents for non-alcoholic fatty liver disease (NAFLD). This study aimed to identify key genes/proteins involved in NAFLD pathogenesis and progression and to evaluate miRNAs influencing their expression.

Methods

Gene expression profiles from datasets GSE151158, GSE163211, GSE135251, GSE167523, GSE46300, and online databases were analyzed to identify significant NAFLD-related genes. Then, protein-protein interaction networks and module analysis identified hub genes/proteins, which were validated using real-time PCR in oleic acid-treated HepG2 cells. Functional enrichment analysis evaluated signaling pathways and biological processes. Gene-miRNA interaction networks identified miRNAs targeting critical NAFLD genes.

Results

The most critical overexpressed hub genes/proteins included: TNF, VEGFA, TLR4, CYP2E1, ACE, SCD, FASN, SREBF2, and TGFB1 based on PPI network analysis, of which TNF, TLR4, SCD, FASN, SREBF2, and TGFB1 were up-regulated in oleic acid-treated HepG2 cells. Functional enrichment analysis for biological processes highlighted programmed necrotic cell death, lipid metabolic process response to reactive oxygen species, and inflammation. In the Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis, the highest adjusted P-value signaling pathways encompassed AGE-RAGE in diabetic complications, TNF, and HIF-1 signaling pathways. In gene-miRNA network analysis, miR-16 and miR-124 were highlighted as the miRNAs exerting the most influence on important NAFLD-related genes.

Conclusion

In silico analyses identified NAFLD therapeutic targets and miRNA candidates to guide further experimental investigation.

Unveiling the Complex Role of Exosomes in Alzheimer's Disease

Alzheimer's disease (AD) is the most common neurodegenerative illness, characterized by memory loss and cognitive decline, accounting for 60-80% of dementia cases. AD is characterized by senile plaques made up of amyloid β (Aβ) protein, intracellular neurofibrillary tangles caused by hyperphosphorylation of tau protein linked with microtubules, and neuronal loss. Currently, therapeutic treatments and nanotechnological developments are effective in treating the symptoms of AD, but a cure for the illness has not yet been found. Recently, the increased study of extracellular vesicles (EVs) has led to a growing awareness of their significant involvement in neurodegenerative disorders, including AD. Exosomes are small extracellular vesicles that transport various components including messenger RNAs, non-coding RNAs, proteins, lipids, DNA, and other bioactive compounds from one cell to another, facilitating information transmission and material movement. There is growing evidence indicating that exosomes have complex functions in AD. Exosomes may have a dual role in Alzheimer's disease by contributing to neuronal death and also helping to alleviate the pathological progression of the disease. Therefore, the primary aim of this review is to outline the updated understandings on exosomes biogenesis and many functions of exosomes in the generation, conveyance, distribution, and elimination of hazardous proteins related to Alzheimer's disease. This review is intended to provide novel insights for understanding the development, specific treatment, and early detection of Alzheimer's disease.

Management of traumatic spinal cord injury: A current concepts review of contemporary and future treatment

Spinal Cord Injury (SCI) is a condition leading to inflammation, edema, and dysfunction of the spinal cord, most commonly due to trauma, tumor, infection, or vascular disturbance. Symptoms include sensory and motor loss starting at the level of injury; the extent of damage depends on injury severity as detailed in the ASIA score. In the acute setting, maintaining mean arterial pressure (MAP) higher than 85 mmHg for up to 7 days following injury is preferred; although caution must be exercised when using vasopressors such as phenylephrine due to serious side effects such as pulmonary edema and death. Decompression surgery (DS) may theoretically relieve edema and reduce intraspinal pressure, although timing of surgery remains a matter of debate. Methylprednisolone (MP) is currently used due to its ability to reduce inflammation but more recent studies question its clinical benefits, especially with inconsistency in recommending it nationally and internationally. The choice of MP is further complicated by conflicting evidence for optimal timing to initiate treatment, and by the reported observation that higher doses are correlated with increased risk of complications. Thyrotropin-releasing hormone may be beneficial in less severe injuries. Finally, this review discusses many options currently being researched and have shown promising pre-clinical results.

Applications of Stem Cell-Derived Extracellular Vesicles in Nerve Regeneration

Extracellular vesicles (EVs), including exosomes, microvesicles, and other lipid vesicles derived from cells, play a pivotal role in intercellular communication by transferring information between cells. EVs secreted by progenitor and stem cells have been associated with the therapeutic effects observed in cell-based therapies, and they also contribute to tissue regeneration following injury, such as in orthopaedic surgery cases. This review explores the involvement of EVs in nerve regeneration, their potential as drug carriers, and their significance in stem cell research and cell-free therapies. It underscores the importance of bioengineers comprehending and manipulating EV activity to optimize the efficacy of tissue engineering and regenerative therapies.

An ALS-associated mutation dysregulates microglia-derived extracellular microRNAs in a sex-specific manner

Evidence suggests the presence of microglial activation and microRNA (miRNA) dysregulation in amyotrophic lateral sclerosis (ALS), the most common form of adult motor neuron disease. However, few studies have investigated whether the miRNA dysregulation originates from microglia. Furthermore, TDP-43 (encoded by TARDBP), involved in miRNA biogenesis, aggregates in tissues of ∼98% of ALS cases. Thus, this study aimed to determine whether expression of the ALS-linked TDP-43M337V mutation in a transgenic mouse model dysregulates microglia-derived miRNAs. RNA sequencing identified several dysregulated miRNAs released by transgenic microglia and a differential miRNA release by lipopolysaccharide-stimulated microglia, which was more pronounced in cells from female mice. We validated the downregulation of three candidate miRNAs, namely, miR-16-5p, miR-99a-5p and miR-191-5p, by reverse transcription quantitative polymerase chain reaction (RT-qPCR) and identified their predicted targets, which primarily include genes involved in neuronal development and function. These results suggest that altered TDP-43 function leads to changes in the miRNA population released by microglia, which may in turn be a source of the miRNA dysregulation observed in the disease. This has important implications for the role of neuroinflammation in ALS pathology and could provide potential therapeutic targets.

Analysis of the therapeutic potential of miR-124 and miR-16 in non-alcoholic fatty liver disease

BACKGROUNDS

Non-alcoholic fatty liver disease (NAFLD) is a common condition affecting >25 % of the population worldwide. This disorder ranges in severity from simple steatosis (fat accumulation) to severe steatohepatitis (inflammation), fibrosis and, at its end-stage, liver cancer. A number of studies have identified overexpression of several key genes that are critical in the initiation and progression of NAFLD. MiRNAs are potential therapeutic agents that can regulate several genes simultaneously. Therefore, we transfected cell lines with two key miRNAs involved in targeting NAFLD-related genes.

METHODS

The suppression effects of the investigated miRNAs (miR-124 and miR-16) and genes (TNF, TLR4, SCD, FASN, SREBF2, and TGFβ-1) from our previous study were investigated by real-time PCR in Huh7 and HepG2 cells treated with oleic acid. Oil red O staining and the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay were utilized to assess cell lipid accumulation and cytotoxic effects of the miRNAs, respectively. The pro-oxidant-antioxidant balance (PAB) assay was undertaken for miR-16 and miR-124 after cell transfection.

RESULTS

Following transfection of miRNAs into HepG2, oil red O staining showed miR-124 and miR-16 reduced oleic acid-induced lipid accumulation by 35.2 % and 28.6 % respectively (p < 0.05). In Huh7, miR-124 and miR-16 reduced accumulation by 23.5 % and 31.3 % respectively (p < 0.05) but without impacting anti-oxidant activity. Real-time PCR in HepG2 revealed miR-124 decreased expression of TNF by 0.13-fold, TLR4 by 0.12-fold and SREBF2 by 0.127-fold (p < 0.05). miR-16 decreased TLR4 by 0.66-fold and FASN by 0.3-fold (p < 0.05). In Huh7, miR-124 decreased TNF by 0.12-fold and FASN by 0.09-fold (p < 0.05). miR-16 decreased SCD by 0.28-fold and FASN by 0.64-fold (p < 0.05). MTT assays showed, in HepG2, viability was decreased 24.7 % by miR-124 and decreased 33 % by miR-16 at 72 h (p < 0.05). In Huh7, miR-124 decreased viability 42 % at 48 h and 29.33 % at 72 h (p < 0.05), while miR-16 decreased viability by 32.3 % (p < 0.05).

CONCLUSION

These results demonstrate the ability of miR-124 and miR-16 to significantly reduce lipid accumulation and expression of key pathogenic genes associated with NAFLD through direct targeting. Though this requires further in vivo investigation.

Tumor Suppressor MicroRNAs in Clinical and Preclinical Trials for Neurological Disorders

Cancers and neurological disorders are two major types of diseases in humans. We developed the concept called the "Aberrant Cell Cycle Disease (ACCD)" due to the accumulating evidence that shows that two different diseases share the common mechanism of aberrant cell cycle re-entry. The aberrant cell cycle re-entry is manifested as kinase/oncoprotein activation and tumor suppressor (TS) inactivation, which are associated with both tumor growth in cancers and neuronal death in neurological disorders. Therefore, some cancer therapies (e.g., kinase/oncogene inhibition and TS elevation) can be leveraged for neurological treatments. MicroRNA (miR/miRNA) provides a new style of drug-target binding. For example, a single tumor suppressor miRNA (TS-miR/miRNA) can bind to and decrease tens of target kinases/oncogenes, producing much more robust efficacy to block cell cycle re-entry than inhibiting a single kinase/oncogene. In this review, we summarize the miRNAs that are altered in both cancers and neurological disorders, with an emphasis on miRNA drugs that have entered into clinical trials for neurological treatment.

Isolation and usage of exosomes in central nervous system diseases

BACKGROUND

Exosomes are vesicles secreted by all types of mammalian cells. They are characterized by a double-layered lipid membrane structure. They serve as carriers for a plethora of signal molecules, including DNA, RNA, proteins, and lipids. Their unique capability of effortlessly crossing the blood-brain barrier underscores their critical role in the progression of various neurological disorders. This includes, but is not limited to, diseases such as Alzheimer's, Parkinson's, and ischemic stroke. Establishing stable and mature methods for isolating exosomes is a prerequisite for the study of exosomes and their biomedical significance. The extraction technologies of exosomes include differential centrifugation, density gradient centrifugation, size exclusion chromatography, ultrafiltration, polymer coprecipitation, immunoaffinity capture, microfluidic, and so forth. Each extraction technology has its own advantages and disadvantages, and the extraction standards of exosomes have not been unified internationally.

AIMS

This review aimed to showcase the recent advancements in exosome isolation techniques and thoroughly compare the advantages and disadvantages of different methods. Furthermore, the significant research progress made in using exosomes for diagnosing and treating central nervous system (CNS) diseases has been emphasized.

CONCLUSION

The varying isolation methods result in differences in the concentration, purity, and size of exosomes. The efficient separation of exosomes facilitates their widespread application, particularly in the diagnosis and treatment of CNS diseases.

Herpes simplex virus type 1 modifies the protein composition of extracellular vesicles to promote neurite outgrowth and neuroinfection

The highly prevalent herpes simplex virus type 1 (HSV-1) causes a range of diseases, including cold sores, blinding keratitis, and life-threatening encephalitis. HSV-1 initially replicates in epithelial cells, enters the peripheral nervous system via neurites, and establishes lifelong infection in the neuronal cell bodies. Neurites are highly dynamic structures that grow or retract in response to attractive or repulsive cues, respectively. Here, we show that infection with HSV-1, but not with a mutant virus lacking glycoprotein G (gG), reduced the repulsive effect of epithelial cells on neurite outgrowth and facilitated HSV-1 invasion of neurons. HSV-1 gG was required and sufficient to induce neurite outgrowth by modifying the protein composition of extracellular vesicles, increasing the amount of neurotrophic and neuroprotective proteins, including galectin-1. Antibodies directed against galectin-1 neutralized the capacity of extracellular vesicles released from HSV-1-infected cells to promote neurite outgrowth. Our study provides new insights into the neurotropism of HSV-1 and identifies a viral protein that modifies the protein composition of extracellular vesicles to stimulate neurite outgrowth and invasion of the nervous system.IMPORTANCEHerpes simplex virus type 1 (HSV-1) must infect neurites (or nerve endings) to establish a chronic infection in neurons. Neurites are highly dynamic structures that retract or grow in the presence of repulsive or attractive proteins. Some of these proteins are released by epithelial cells in extracellular vesicles and act upon interaction with their receptor present on neurites. We show here that HSV-1 infection of epithelial cells modulated their effect on neurites, increasing neurite growth. Mechanistically, HSV-1 glycoprotein G (gG) modifies the protein composition of extracellular vesicles released by epithelial cells, increasing the amount of attractive proteins that enhance neurite outgrowth and facilitate neuronal infection. These results could inform of therapeutic strategies to block HSV-1 induction of neurite outgrowth and, thereby, neuronal infection.

Hydrogel-mediated extracellular vesicles for enhanced wound healing: the latest progress, and their prospects for 3D bioprinting

Extracellular vesicles have shown promising tissue recovery-promoting effects, making them increasingly sought-after for their therapeutic potential in wound treatment. However, traditional extracellular vesicle applications suffer from limitations such as rapid degradation and short maintenance during wound administration. To address these challenges, a growing body of research highlights the role of hydrogels as effective carriers for sustained extracellular vesicle release, thereby facilitating wound healing. The combination of extracellular vesicles with hydrogels and the development of 3D bioprinting create composite hydrogel systems boasting excellent mechanical properties and biological activity, presenting a novel approach to wound healing and skin dressing. This comprehensive review explores the remarkable mechanical properties of hydrogels, specifically suited for loading extracellular vesicles. We delve into the diverse sources of extracellular vesicles and hydrogels, analyzing their integration within composite hydrogel formulations for wound treatment. Different composite methods as well as 3D bioprinting, adapted to varying conditions and construction strategies, are examined for their roles in promoting wound healing. The results highlight the potential of extracellular vesicle-laden hydrogels as advanced therapeutic tools in the field of wound treatment, offering both mechanical support and bioactive functions. By providing an in-depth examination of the various roles that these composite hydrogels can play in wound healing, this review sheds light on the promising directions for further research and development. Finally, we address the challenges associated with the application of composite hydrogels, along with emerging trends of 3D bioprinting in this domain. The discussion covers issues such as scalability, regulatory considerations, and the translation of this technology into practical clinical settings. In conclusion, this review underlines the significant contributions of hydrogel-mediated extracellular vesicle therapy to the field of 3D bioprinting and wound healing and tissue regeneration. It serves as a valuable resource for researchers and practitioners alike, fostering a deeper understanding of the potential benefits, applications, and challenges involved in utilizing composite hydrogels for wound treatment.

Astrocyte-Derived Exosomal miR-148a-3p Suppresses Neuroinflammation and Restores Neurological Function in Traumatic Brain Injury by Regulating the Microglial Phenotype

Interactions between astrocytes and microglia play an important role in the regeneration and repair of traumatic brain injury (TBI), and exosomes are involved in cell-cell interactions. A TBI model was constructed in rats. Brain extract (Ext) was isolated 1 d after TBI. Astrocyte-derived exosomes were obtained by coculturing Ext with primary astrocytes, and the morphology of exosomes was observed by electron microscopy. The isolated exosomes were cocultured with microglia to observe phenotypic changes in M1 and M2 markers. Aberrant RNA expression was detected in necrotic brain tissue and edematous brain tissue. The role of miR-148a-3p in regulating microglial phenotype was explored by knocking down or overexpressing miR-148a-3p. Finally, the effect of miR-148a-3p on TBI was studied in a rat TBI model. Astrocyte-derived exosomes stimulated by Ext promoted the transition of microglia from the M1 phenotype to the M2 phenotype. MiR-148a-3p was highly expressed in TBI. Transfecting miR-148a-3p promoted the transition of microglia from the M1 phenotype to the M2 phenotype and inhibited the lipopolysaccharide-induced inflammatory response in pre-microglia. In a rat TBI model, miR-148a-3p significantly improved the modified neurological severity score and attenuated brain injury, which promoted the transition of microglia from the M1 phenotype to the M2 phenotype. MiR-148a-3p alleviated TBI by inhibiting the nuclear factor κB pathway. Astrocyte-derived exosomal miR-148a-3p regulates the microglial phenotype, inhibits neuroinflammation, and restores neurological function in TBI. These results provide new potential targets for the treatment of TBI.

Microglial exosome miR-124-3p in hippocampus alleviates cognitive impairment induced by postoperative pain in elderly mice

Cognitive impairment induced by postoperative pain severely deteriorates the rehabilitation outcomes in elderly patients. The present study focused on the relationship between microglial exosome miR-124-3p in hippocampus and cognitive impairment induced by postoperative pain. Cognitive impairment model induced by postoperative pain was constructed by intramedullary nail fixation after tibial fracture. Morphine intraperitoneally was carried out for postoperative analgesia. Morris water maze tests were carried out to evaluate the cognitive impairment, while mRNA levels of neurotrophic factors (BDNF, NG) and neurodegenerative biomarker (VILIP-1) in hippocampus were tested by q-PCR. Transmission electron microscope was used to observe the axon degeneration in hippocampus. The levels of pro-inflammatory factors (TNF-α, IL-1β, IL-6), the levels of anti-inflammatory factors (Ym, Arg-1, IL-10) and microglia proliferation marker cyclin D1 in hippocampus were measured to evaluate microglia polarization. Bioinformatics analysis was conducted to identify key exosomes while BV-2 microglia overexpressing exosome miR-124-3p was constructed to observe microglia polarization in vitro experiments. Exogenous miR-124-3p-loaded exosomes were injected into hippocampus in vivo. Postoperative pain induced by intramedullary fixation after tibial fracture was confirmed by decreased mechanical and thermal pain thresholds. Postoperative pain induced cognitive impairment, promoted axon demyelination, decreased BDNF, NG and increased VILIP-1 expressions in hippocampus. Postoperative pain also increased pro-inflammatory factors, cyclin D1 and decreased anti-inflammatory factors in hippocampus. However, these changes were all reversed by morphine analgesia. Bioinformatics analysis identified the critical role of exosome miR-124-3p in cognitive impairment, which was confirmed to be down-regulated in hippocampus of postoperative pain mice. BV-2 microglia overexpressing exosome miR-124-3p showed decreased pro-inflammatory factors, cyclin D1 and increased anti-inflammatory factors. In vivo, stereotactic injection of exogenous miR-124-3p into hippocampus decreased pro-inflammatory factors, cyclin D1 and increased anti-inflammatory factors. The cognitive impairment, axon demyelination, decreased BDNF, NG and increased VILIP-1 expressions in hippocampus were all alleviated by exogenous exosome miR-124-3p. Microglial exosome miR-124-3p in hippocampus alleviates cognitive impairment induced by postoperative pain through microglia polarization in elderly mice.