Astrocyte-derived exosomal miR-378a-5p mitigates cerebral ischemic neuroinflammation by modulating NLRP3-mediated pyroptosis

Extracellular Vesicles as Emerging Therapeutic Strategies in Spinal Cord Injury: Ready to Go

Spinal cord injury (SCI) is a prevalent central nervous system disorder that causes significant disability and mortality. Unfortunately, due to the complex pathophysiological mechanisms involved, there remains a critical paucity of effective therapeutic interventions capable of achieving neural tissue regeneration and functional recovery enhancement in SCI patients. The advancements in extracellular vesicles (EVs) as a cell-free therapy for SCI have displayed notable benefits. These include their small size, low immunogenicity, capacity to target specific areas, and ability to cross the blood‒brain barrier (BBB). EVs offer the potential to not only repair tissue damage and stimulate regeneration but also effectively deliver and release them at the site of SCI when combined with diverse biomaterials. This review explores the biological role and importance of EVs in treating SCI, highlighting the combined use of modified EVs with different biomaterials and their potential for future applications. It presents new and hopeful treatment approaches for individuals afflicted with SCI.

The Potential Role of Exosomes in Communication Between Astrocytes and Endothelial Cells

Exosomes are extracellular vesicles secreted by almost all types of cells. Their release allows for the transport of specific regulatory cargo into the recipient cells and the modulation of their activity. Vesicular communication has also been identified as an important mechanism for the regulation of numerous cellular activities in the brain tissue, contributing to proper neuronal functions and brain homeostasis. In this work, we focus on the role of exosomes and extracellular vesicles in the communication between astrocytes and brain endothelial cells, two major components of the blood-brain barrier. We perform a comprehensive review of the latest studies highlighting the role of exosomes in astrocyte-endothelial cell crosstalk within the blood-brain barrier. We have also described the role of particular exosomal miRNAs in the regulation of astrocytes and brain endothelial cell functions, and discuss some future implications.

Neuroinflammation and energy metabolism: a dual perspective on ischemic stroke

Ischemic stroke is a prevalent form of cerebrovascular accident, with its pathogenesis involving the intricate interplay between neuroinflammation and energy metabolism. Cerebral ischemia disrupts oxygen and energy supply, triggering metabolic dysregulation and activating neuroinflammatory responses, ultimately resulting in cellular damage. This review provides an exhaustive analysis of the complex mechanisms of ischemic stroke, with a particular focus on the interaction between neuroinflammation and energy metabolism. The interruption of oxygen and energy supply due to cerebral ischemia initiates metabolic dysregulation and activates neuroinflammatory responses, including the release of inflammatory cytokines and the activation of immune cells, contributing to cellular damage and further metabolic disturbances. Studies indicate that dysregulation of energy metabolism significantly impairs neural cell function and interacts with neuroinflammation, exacerbating ischemic brain injury. Therapeutic strategies primarily concentrate on modulating energy metabolism and suppressing neuroinflammatory responses, emphasizing the importance of in-depth research into their interaction to provide a theoretical foundation for new treatment strategies for ischemic stroke. Future research should focus on how to balance anti-inflammatory treatment with energy regulation to minimize neural damage and promote recovery.

Overexpressed CD73 attenuates GSDMD-mediated astrocyte pyroptosis induced by cerebral ischemia-reperfusion injury through the A2B/NF-κB pathway

Ischemic stroke, resulting from the blockage or narrowing of cerebral vessels, causes brain tissue damage due to ischemia and hypoxia. Although reperfusion therapy is essential to restore blood flow, it may also result in reperfusion injury, causing secondary damage through mechanisms like oxidative stress, inflammation, and excitotoxicity. These effects significantly impact astrocytes, neurons, and endothelial cells, aggravating brain injury and disrupting the blood-brain barrier. CD73, an ectoenzyme that regulates adenosine production through ATP hydrolysis, plays a critical role in purinergic signaling and neuroprotection. During ischemic stroke, CD73 expression is dynamically regulated in response to ischemia and inflammation. It catalyzes the conversion of AMP to adenosine, which activates adenosine receptors to exert neuroprotective effects. Targeting the CD73-adenosine pathway presents a potential therapeutic strategy for mitigating ischemic stroke damage. Pyroptosis, a highly inflammatory form of programmed cell death mediated by inflammasomes like NLRP3 and caspases, plays a significant role in cerebral ischemia-reperfusion injury. Astrocytes, the most abundant CNS cells, contribute to both neuroprotection and injury, with pyroptosis exacerbating inflammation and brain damage. Regulating astrocyte pyroptosis is a promising therapeutic target. Our study investigates CD73's role in regulating astrocyte pyroptosis during ischemia-reperfusion injury. Using CD73 knockout mice and overexpression models, along with in vitro oxygen-glucose deprivation/reperfusion experiments, we found that CD73 overexpression reduces GSDMD-mediated astrocyte pyroptosis via the A2B/NF-κB pathway. These findings offer a novel approach to reducing neuroinflammation, protecting astrocytes, and improving outcomes in ischemic stroke.

Extracellular Vesicle-Derived miRNAs in Ischemic Stroke: Roles in Neuroprotection, Tissue Regeneration, and Biomarker Potential

Ischemic stroke (IS) is one of the most common causes of death and disability worldwide. Despite its prevalence, knowledge about pathophysiology and diagnostic methods remains limited. Extracellular vesicles (EVs) that are released from cellular membranes constitutively, as well as after activation or damage, may contain various intracellular particles, including microRNAs (miRNAs/miR). miRNAs acting as mRNA transcription regulators are secreted in EVs and may be internalized by other cells. This cellular cross-talk is important for the regeneration of the nervous tissue after ischemic injury. Moreover, miRNAs related to stroke pathophysiology were shown to be differentially expressed after an IS episode. miRNAs associated with various types of stem cell-derived EVs were shown to be involved in post-ischemic neuroprotection and tissue regeneration and may be potential therapeutic agents. Therefore, considering their stability in plasma, they are worth investigating also as potential diagnostic/prognostic biomarkers. The present review summarizes the current knowledge about EV-derived miRNAs in the neuronal injury mechanism and their potential in neuroprotection in IS, and discusses the possibilities of further investigation of their use in preclinical research.

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.

Cancer-associated fibroblasts derived-exosomal circ_0076535 promotes esophageal squamous cell carcinoma progression

BackgroundEsophageal cancer (EC) is a common malignant tumor of the digestive tract and an important health-related problem in many developing countries. Esophageal squamous cell carcinoma (ESCC) is the most common subtype of EC. The cancer-associated fibroblasts (CAFs) are the major stromal cells in ESCC microenvironment. They play important role in ESCC proliferation, metastasis, angiogenesis and chemotherapy resistance through paracrine processes. However, the roles of circRNAs enriched in CAF-derived exosmes have not been reported.ObjectiveTo explore the mechanisms of how CAF affects ESCC proliferation and metastasis through paracrine processes and to investigate the role of circRNAs enriched in CAF-derived exosomes.MethodsExosomes were isolated from the conditional medium of CAF using differential ultracentrifugation, and then validated by Nanosight analysis. Exosome secretion inhibitor-GW4869 validates the pro-carcinogenic role of exosomes. The qRT-PCR showed the highest expression of circ_0076535 in the exosomal CircRNA, and knockdown of it confirmed its function. Online bioinformatics tool was utilized to predict the potential target gene of circ_0076535, and captured miR-145-5p as the target gene with high predictive value. The targeting association between miR-145-5p and circ_0076535 is further confirmed by the dual luciferase reporter experiment. The stimulation of tumour development and EMT by the CAF-derived exosome circ_0076535 is further validated in vivo.ResultsIn our research, we found that CAF-derived exosomes increased proliferation, migration, invasion and EMT in ESCC cells. Circ_0076535 was highly enriched in CAF-exosomes and transferred into ESCC cells directly depend on internalization of exosomes. CAF-exosomal circ_0076535 increased the level of circ_0076535 in ESCC cells and induced EMT. Mechanistic experiments revealed circ_0076535 acted as a sponge to absorb miR-145-5p and activated NF-κB signaling pathway.Conclusions: Conclusively, CAF-exosomal circ_0076535 promoted the ESCC progression via miR-145-5p/NF-κB axis and expected to be a potential biomarker for early diagnosis and treatment of ESCC.