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

Roles for Exosomes from Various Cellular Sources in Spinal Cord Injury

Spinal cord injury (SCI) is a severe disorder characterized by regeneration challenges in the central nervous system (CNS), resulting in permanent paralysis, loss of sensation, and abnormal autonomic functions. The complex pathophysiology of SCI poses challenges to traditional treatments, highlighting the urgent need for novel treatment approaches. Exosomes have emerged as promising candidates for SCI therapy because of their ability to deliver a wide range of bioactive molecules, such as RNAs, proteins, and lipids, to target cells with minimal immunogenicity, which contribute to anti-inflammatory, anti-apoptotic, autophagic, angiogenic, neurogenic, and axon remodeling activities. In this study, we classified exosomes from different sources into four categories based on the characteristics of the donor cells (mesenchymal stem cells, neurogenic cells, immune cells, vascular-associated cells) and provided a detailed summary and discussion of the current research progress and future directions for each source. We also conducted an in-depth investigation into the applications of engineered exosomes in SCI therapy, focusing on their roles in drug delivery and combination with surface engineering technologies and tissue engineering strategies. Finally, the challenges and prospects of exosomal clinical applications in SCI repair are described.

A Review of the Neuroprotective Properties of Exosomes Derived from Stem Cells and Exosome-Coated Nanoparticles for Treating Neurodegenerative Diseases and Stroke

Neurological diseases, including neurodegenerative disorders and stroke, represent significant medical challenges due to their complexity and the limitations of current treatment approaches. This review explores the potential of stem cell (SC)-derived exosomes (Exos) as a transformative therapeutic strategy for these diseases. Exos, especially those derived from SCs, exhibit natural targeting ability, biocompatibility, and the capacity to cross the blood-brain barrier (BBB), making them ideal vehicles for drug delivery. This review provides an in-depth discussion of the properties and advantages of SC-Exos. It highlights their potential synergistic benefits in therapeutic approaches to treat neurological diseases. This article discusses the mechanisms of action of SC-Exos, highlighting their ability to target specific cells, modulate disease pathways, and provide controlled release of therapeutic agents. Applications in specific neurological disorders have been investigated, demonstrating the potential to improve outcomes in conditions such as Alzheimer's Disease (AD), Parkinson's Disease (PD), and stroke. Moreover, Exos-coated nanoparticles (NPs) combine the natural properties of Exos with the multifunctionality of NPs. This integration takes advantage of exosome membrane biocompatibility and targeting capabilities while preserving NPs' beneficial features, such as drug loading and controlled release. As a result, Exos-coated NPs may enhance the precision, efficacy, and safety of therapeutic interventions. In conclusion, SC-Exos represent a promising and innovative approach to treating neurological diseases.

Harnessing stem cell-derived exosomes: a promising cell-free approach for spinal cord injury

Spinal cord injury (SCI) is a severe injury to the central nervous system that often results in permanent neurological dysfunction. Current treatments have limited efficacy and face challenges in restoring neurological function after injury. Recently, stem cell-derived exosomes have gained attention as an experimental treatment for SCI due to their unique properties, including superior biocompatibility, minimal immunogenicity and non-tumorigenicity. With their potential as a cell-free therapy, exosomes promote SCI repair by enhancing nerve regeneration, reducing inflammation and stabilizing the blood-spinal cord barrier. This review summarizes advances in stem cell-derived exosome research for SCI over the past years, focusing on their mechanisms and future prospects. Despite their promising therapeutic potential, clinical translation remains challenging due to standardization of exosome isolation protocols, compositional consistency and long-term safety profiles that require further investigation.

Manipulation of Oxygen Tension in Damaged Regions via Hypoxia-Induced IPN Hydrogel Microspheres for Intervertebral Disc Regeneration

Disruption of low oxygen tension homeostasis during intervertebral disc degeneration inhibits endogenous stem cell viability and function, posing a challenge for endogenous regeneration. Here, to achieve sustained hypoxia manipulation, constructed hypoxia-inducible interpenetrating polymer network (IPN) hydrogel microspheres (HIMS) are constructed by microfluidics to integrate the hypoxic system with a stabilizing network. The IPN is synthesized through a two-step polymerization process, consisting of rapid photo-crosslinked gelatin methacrylate anhydride (GM) polymer I and slow enzyme-crosslinked vanillin-grafted gelatin (GV) polymer II. The enzymatic reaction between GV and laccase is able to create a hypoxic microenvironment to modulate oxygen tension in situ within the injured region. HIMS can reduce microenvironmental oxygen tension by 1/3 and maintain a hypoxic microenvironment for up to 5 days, thereby activating the PI3K/AKT/HIF-1α signaling pathway in endogenous stem cells to promote differentiation into nucleus pulposus-like cells. Additionally, NSC-Exos are loaded onto HIMS to trigger endogenous progenitor/stem cell recruitment and migration. Both in vitro and in vivo assays demonstrate that NSC-Exos@HIMS facilitates stem cell recruitment, targets differentiation, and stimulates extracellular matrix synthesis. Overall, the microspheres established herein provide a novel strategy for manipulating oxygen tension and enhancing endogenous tissue regeneration in injured regions during intervertebral disc degeneration.

The roles of extracellular vesicles in mental disorders: information carriers, biomarkers, therapeutic agents

Mental disorders are complex conditions that encompass various symptoms and types, affecting approximately 1 in 8 people globally. They place a significant burden on both families and society as a whole. So far, the etiology of mental disorders remains poorly understood, making diagnosis and treatment particularly challenging. Extracellular vesicles (EVs) are nanoscale particles produced by cells and released into the extracellular space. They contain bioactive molecules including nucleotides, proteins, lipids, and metabolites, which can mediate intercellular communication and are involved in various physiological and pathological processes. Recent studies have shown that EVs are closely linked to mental disorders like schizophrenia, major depressive disorder, and bipolar disorder, playing a key role in their development, diagnosis, prognosis, and treatment. Therefore, based on recent research findings, this paper aims to describe the roles of EVs in mental disorders and summarize their potential applications in diagnosis and treatment, providing new ideas for the future clinical transformation and application of EVs.

Mitochondria transfer for myelin repair

Demyelination is a common feature of neuroinflammatory and degenerative diseases of the central nervous system (CNS), such as multiple sclerosis (MS). It is often linked to disruptions in intercellular communication, bioenergetics and metabolic balance accompanied by mitochondrial dysfunction in cells such as oligodendrocytes, neurons, astrocytes, and microglia. Although current MS treatments focus on immunomodulation, they fail to stop or reverse demyelination's progression. Recent advancements highlight intercellular mitochondrial exchange as a promising therapeutic target, with potential to restore metabolic homeostasis, enhance immunomodulation, and promote myelin repair. With this review we will provide insights into the CNS intercellular metabolic decoupling, focusing on the role of mitochondrial dysfunction in neuroinflammatory demyelinating conditions. We will then discuss emerging cell-free biotherapies exploring the therapeutic potential of transferring mitochondria via biogenic carriers like extracellular vesicles (EVs) or synthetic liposomes, aimed at enhancing mitochondrial function and metabolic support for CNS and myelin repair. Lastly, we address the key challenges for the clinical application of these strategies and discuss future directions to optimize mitochondrial biotherapies. The advancements in this field hold promise for restoring metabolic homeostasis, and enhancing myelin repair, potentially transforming the therapeutic landscape for neuroinflammatory and demyelinating diseases.

Regulation of dynamic spatiotemporal inflammation by nanomaterials in spinal cord injury

Spinal cord injury (SCI) is a common clinical condition of the central nervous system that can lead to sensory and motor impairment below the injury level or permanent loss of function in severe cases. Dynamic spatiotemporal neuroinflammation is vital to neurological recovery, which is collectively constituted by the dynamic changes in a series of inflammatory cells, including microglia, neutrophils, and astrocytes, among others. Immunomodulatory nanomaterials can readily improve the therapeutic effects and simultaneously overcome various drawbacks associated with treatment, such as the off-target side effects and loss of bioactivity of immune agents during circulation. In this review, we discuss the role of dynamic spatiotemporal inflammation in secondary injuries after SCI, elaborate on the mechanism of action and effect of existing nanomaterials in treating SCI, and summarize the mechanism(s) whereby they regulate inflammation. Finally, the challenges and prospects associated with using nanotechnology to modulate immunotherapy are discussed to provide new insights for future treatment. Deciphering the intricate spatiotemporal mechanisms of neuroinflammation in SCI requires further in-depth studies. Therefore, SCI continues to represent a formidable challenge.

Nanoparticle Strategies for Treating CNS Disorders: A Comprehensive Review of Drug Delivery and Theranostic Applications

This review aims to address the significant challenges of treating central nervous system (CNS) disorders such as neurodegenerative diseases, strokes, spinal cord injuries, and brain tumors. These disorders are difficult to manage due to the complexity of disease mechanisms and the protective blood-brain barrier (BBB), which restricts drug delivery. Recent advancements in nanoparticle (NP) technologies offer promising solutions, with potential applications in drug delivery, neuroprotection, and neuroregeneration. By examining current research, we explore how NPs can cross the BBB, deliver medications directly to targeted CNS regions, and enhance both diagnostics and treatment. Key NP strategies, such as passive targeting, receptor-mediated transport, and stimuli-responsive systems, demonstrate encouraging results. Studies show that NPs may improve drug delivery, minimize side effects, and increase therapeutic effectiveness in models of Alzheimer's, Parkinson's, stroke, and glioblastoma. NP technologies thus represent a promising approach for CNS disorder management, combining drug delivery and diagnostic capabilities to enable more precise and effective treatments that could significantly benefit patient outcomes.

Role of Redox Homeostasis in the Communication Between Brain and Liver Through Extracellular Vesicles

Extracellular vesicles (EVs) are small, membrane-bound particles secreted by cells into the extracellular environment, playing an increasingly recognized role in inter-organ communication and the regulation of various physiological processes. Regarding the redox homeostasis context, EVs play a pivotal role in propagating and mitigating oxidative stress signals across different organs. Cells under oxidative stress release EVs containing signaling molecules that can influence the redox status of distant cells and tissues. EVs are starting to be recognized as contributors to brain-liver communication. Therefore, in this review, we show how redox imbalance can affect the release of EVs in the brain and liver. We propose EVs as mediators of redox homeostasis in the brain-liver axis.

Human neural stem cell-derived artificial organelles to improve oxidative phosphorylation

Oxidative phosphorylation (OXPHOS) in the mitochondrial inner membrane is a therapeutic target in many diseases. Neural stem cells (NSCs) show progress in improving mitochondrial dysfunction in the central nervous system (CNS). However, translating neural stem cell-based therapies to the clinic is challenged by uncontrollable biological variability or heterogeneity, hindering uniform clinical safety and efficacy evaluations. We propose a systematic top-down design based on membrane self-assembly to develop neural stem cell-derived oxidative phosphorylating artificial organelles (SAOs) for targeting the central nervous system as an alternative to NSCs. We construct human conditionally immortal clone neural stem cells (iNSCs) as parent cells and use a streamlined closed operation system to prepare neural stem cell-derived highly homogenous oxidative phosphorylating artificial organelles. These artificial organelles act as biomimetic organelles to mimic respiration chain function and perform oxidative phosphorylation, thus improving ATP synthesis deficiency and rectifying excessive mitochondrial reactive oxygen species production. Conclusively, we provide a framework for a generalizable manufacturing procedure that opens promising prospects for disease treatment.

Extracellular vesicles as nanotheranostic platforms for targeted neurological disorder interventions

Central Nervous System (CNS) disorders represent a profound public health challenge that affects millions of people around the world. Diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), and traumatic brain injury (TBI) exemplify the complexities and diversities that complicate their early detection and the development of effective treatments. Amid these challenges, the emergence of nanotechnology and extracellular vesicles (EVs) signals a new dawn for treating and diagnosing CNS ailments. EVs are cellularly derived lipid bilayer nanosized particles that are pivotal in intercellular communication within the CNS and have the potential to revolutionize targeted therapeutic delivery and the identification of novel biomarkers. Integrating EVs with nanotechnology amplifies their diagnostic and therapeutic capabilities, opening new avenues for managing CNS diseases. This review focuses on examining the fascinating interplay between EVs and nanotechnology in CNS theranostics. Through highlighting the remarkable advancements and unique methodologies, we aim to offer valuable perspectives on how these approaches can bring about a revolutionary change in disease management. The objective is to harness the distinctive attributes of EVs and nanotechnology to forge personalized, efficient interventions for CNS disorders, thereby providing a beacon of hope for affected individuals. In short, the confluence of EVs and nanotechnology heralds a promising frontier for targeted and impactful treatments against CNS diseases, which continue to pose significant public health challenges. By focusing on personalized and powerful diagnostic and therapeutic methods, we might improve the quality of patients.

Unlocking the Therapeutic Potential of Exosomes Derived From Nasal Olfactory Mucosal Mesenchymal Stem Cells: Restoring Synaptic Plasticity, Neurogenesis, and Neuroinflammation in Schizophrenia

BACKGROUND AND HYPOTHESIS

Schizophrenia (SCZ) is a multifaceted mental disorder marked by a spectrum of symptoms, including hallucinations, delusions, cognitive deficits, and negative symptoms. Its etiology involves intricate interactions between genetic and environmental factors, posing significant challenges for effective treatment. We hypothesized that intranasal administration of exosomes derived from nasal olfactory mucosal mesenchymal stem cells (OM-MSCs-exos) could alleviate SCZ-like behaviors in a murine model induced by methylazoxymethanol (MAM).

STUDY DESIGN

We conducted a comprehensive investigation to assess the impact of intranasally delivered OM-MSC-exos on SCZ-like behaviors in MAM-induced mice. This study encompassed behavioral assessments, neuroinflammatory markers, glial activation, synaptic protein expression, and neurogenesis within the hippocampus.

STUDY RESULTS

Our findings demonstrated that intranasal administration of OM-MSC-exos effectively ameliorated SCZ-like behaviors, specifically addressing social withdrawal and sensory gating deficits in the MAM-induced murine model. Furthermore, OM-MSC-exos intervention yielded a reduction in neuroinflammatory markers and a suppression of microglial activation within the hippocampus. Simultaneously, we observed an upregulation of key synaptic protein expression, including PSD95 and TH, the rate-limiting enzyme for dopamine biosynthesis.

CONCLUSIONS

Our study underscores the therapeutic potential of OM-MSC-exos in mitigating SCZ-like behavior. The OM-MSC-exos have the capacity to modulate glial cell activation, diminish neuroinflammation, and promote BDNF-associated synaptic plasticity and neurogenesis, thus ameliorating SCZ-like behaviors. In summary, intranasal administration of OM-MSC-exos offers a multifaceted approach to address SCZ mechanisms, promising innovative treatments for this intricate disorder.

Transplantation of Neural Stem Cells-Overexpressed Ku70 Improves Neurological Deficits in a Mice Model of Cerebral Ischemia Stroke

Cerebral ischemic stroke is a cerebrovascular disease, which is related to DNA damage. Many researches have shown that Ku70 is a key regulator for DNA damage. Here, we aimed to explore Ku70 roles in cerebral ischemic stroke and its potential molecular mechanism. In our study, neural stem cells (NSCs) were induced by oxygen-glucose deprivation/reoxygenation (OGD/R) for constructing cerebral ischemic stroke cell model. CCK8 assay, Brdu/GFP staining, flow cytometry and TUNEL staining were performed to examine cell proliferation, cell cycle and apoptosis, respectively. Relative mRNA and protein levels were detected by quantitative real-time PCR and western blot analysis, respectively. Ku70 positive cells were examined by immunofluorescence staining. Comet assay was employed to determine DNA damage. Animal experiments were performed to assess the effect of transplanting NSCs and Ku70-overexpressed NSCs on neurological deficits, infarct volume, brain edema and blood‒brain barrier (BBB) integrity in middle cerebral artery occlusion (MCAO) model. Our data found that Ku70 expression was decreased in NSCs after OGD/R. Overexpression of Ku70 reduced DNA damage and apoptosis of OGD/R-induced NSCs. Knockdown of Ku70 promoted the activity of ATM/p53. Moreover, KU60019 (ATM-specific inhibitor) reversed the promoting effects of Ku70 silencing on DNA damage and apoptosis in OGD/R-induced NSCs. In animal experiments, transplantation of NSCs-overexpressed Ku70 enhanced cell survival, improved motor function, reduced infarct volume, relieved brain edema and alleviated BBB dysfunction in MCAO mice models. In conclusion, Ku70 overexpression repressed the DNA damage and apoptosis in OGD/R-induced NSCs by regulating ATM/p53 pathway, and transplantation of NSCs-overexpressed Ku70 played neuroprotective effects in MCAO mice models.

Microglia and Stem Cells for Ischemic Stroke Treatment-Mechanisms, Current Status, and Therapeutic Challenges

Ischemic stroke is one of the major causes of death and disability. Since the currently used treatment option of reperfusion therapy has several limitations, ongoing research is focusing on the neuroprotective effects of microglia and stem cells. By exerting the bystander effect, secreting exosomes and forming biobridges, mesenchymal stem cells (MSCs), neural stem cells (NSCs), induced pluripotent stem cells (iPSCs), and multilineage-differentiating stress-enduring cells (Muse cells) have been shown to stimulate neurogenesis, angiogenesis, cell migration, and reduce neuroinflammation. Exosome-based therapy is now being extensively researched due to its many advantageous properties over cell therapy, such as lower immunogenicity, no risk of blood vessel occlusion, and ease of storage and modification. However, although preclinical studies have shown promising therapeutic outcomes, clinical trials have been associated with several translational challenges. This review explores the therapeutic effects of preconditioned microglia as well as various factors secreted in stem cell-derived extracellular vesicles with their mechanisms of action explained. Furthermore, an overview of preclinical and clinical studies is presented, explaining the main challenges of microglia and stem cell therapies, and providing potential solutions. In particular, a highlight is the use of novel stem cell therapy of Muse cells, which bypasses many of the conventional stem cell limitations. The paper concludes with suggestions for directions in future neuroprotective research.