Astrocyte-Derived Extracellular Vesicles for Ischemic Stroke: Therapeutic Potential and Prospective

Reactive astrocyte-derived exosomes enhance intracranial lymphatic drainage in mice after intracranial hemorrhage

BACKGROUND

After intracranial hemorrhage (ICH), the formation of primary hematoma foci leads to the development of secondary brain injury factors such as perihematomal edema (PHE) and accumulation of toxic metabolites, which severely affect the survival and prognosis of patients. The intracerebral lymphatic system, proposed by Jeffrey J. Iliff et al., plays an important role in central nervous system (CNS) fluid homeostasis and waste removal, while reactive astrocyte-derived exosomes have shown therapeutic potential in CNS disorders. Our study focuses on the effects of hemin-treated reactive astrocyte-derived exosomes on the functional integrity of the glymphatic system (GLS) after ICH and their potential mechanism of action in repairing brain injury.

METHODS

Hemin, an iron-rich porphyrin compound, was used to construct the in vitro model of ICH. Primary astrocytes were treated with complete medium supplemented with different concentrations of hemin to obtain exosomes secreted by them, and mice with ICH induced by the collagenase method were intervened by intranasal administration. Solute clearance efficiency was assessed by intracranial injection of cerebrospinal fluid tracers and fluorescent magnetic beads. Immunofluorescence analysis of Aquaporin 4 (AQP4) polarization and astrocyte proliferation. Magnetic Resonance Imaging was used to visualize and quantify the volume of hematoma foci and PHE, and Western Blot was used to analyze the accumulation of toxic metabolites, while neuronal apoptosis was detected by a combination of TUNEL assay apoptosis detection kit and Nissl staining, and their functional status was analyzed. Gait analysis software was used to detect functional recovery of the affected limb in mice.

RESULTS

Exosomes from hemin treated astrocytes facilitated the recovery of AQP4 polarization and attenuated astrocyte proliferation around hematoma foci in mice with ICH, thereby promoting the recovery of the GLS. Meanwhile, exosomes from hemin treated astrocytes reduced PHE and toxic protein accumulation, decreased apoptosis of cortical neurons on the affected side, and facilitated recovery of motor function of the affected limb, and these effects were blocked by TGN020, an AQP4-specific inhibitor.

CONCLUSIONS

Exosomes from hemin treated astrocytes attenuated secondary brain injury and neurological deficits in mice with ICH by promoting the repair of GLS injury.

Astrocyte-Derived Extracellular Vesicles Alleviate Optic Nerve Injury Through Remodeling of Retinal Microenvironmental Homeostasis

Purpose

Traumatic optic neuropathy (TON) leads to the loss of retinal ganglion cells (RGCs) and results in permanent visual impairment. Protecting and regenerating RGCs is crucial for the treatment of TON. Studies have demonstrated that astrocyte-derived extracellular vesicles (ADEVs) exhibit neuroprotective effects in models of central nervous system (CNS) injury. This study aimed to investigate whether ADEVs have a similar neuroprotective effect on RGCs in an optic nerve crush (ONC) rat model.

Methods

ADEVs were collected from primary rat astrocytes, and an ONC model was established to evaluate the effects of ADEVs on retinal structure and visual function using optical coherence tomography (OCT), hematoxylin and eosin (H&E) staining, and flash visual evoked potential (f-VEP) analysis. Immunofluorescence was used to examine RGCs and investigate reactive gliotic changes. Additionally, miRNA sequencing of ADEVs and retinal mRNA sequencing were performed to identify the potential mechanisms involved.

Results

ADEVs protected RGCs from progressive loss and improved visual function. ADEVs also significantly increased the expression of glial fibrillary acidic protein (GFAP) and modulated microglial activation. The miRNAs associated with ADEVs were targeted by neuroprotective signals, such as MAPK, PI3K-AKT, and TNF-α, and through the targeting network generated via retinal mRNA sequencing, we found that potential functional genes, such as THBS1, PAK3, and Gstm1, likely participate in microenvironmental regulation.

Conclusions

We discovered that ADEVs play a neuroprotective role in optic nerve injury. Our findings provide a new cell-free therapeutic strategy for optic neuropathy.

From Physiology to Pathology of Astrocytes: Highlighting Their Potential as Therapeutic Targets for CNS Injury

In the mammalian central nervous system (CNS), astrocytes are the ubiquitous glial cells that have complex morphological and molecular characteristics. These fascinating cells play essential neurosupportive and homeostatic roles in the healthy CNS and undergo morphological, molecular, and functional changes to adopt so-called 'reactive' states in response to CNS injury or disease. In recent years, interest in astrocyte research has increased dramatically and some new biological features and roles of astrocytes in physiological and pathological conditions have been discovered thanks to technological advances. Here, we will review and discuss the well-established and emerging astroglial biology and functions, with emphasis on their potential as therapeutic targets for CNS injury, including traumatic and ischemic injury. This review article will highlight the importance of astrocytes in the neuropathological process and repair of CNS injury.

Advancing Neurological Health: Insights into Aging, Immunity, and Vascular Dynamics

This editorial provides an overview of recent advancements in the understanding and treatment of neurological disorders, focusing on aging, immunity, and blood flow, as featured in this special issue. The first section explores the importance of identifying biomarkers of aging and aging-related diseases, such as Alzheimer's Disease, highlighting the emerging role of saliva-based biomarkers and the gut-brain axis in disease diagnosis and management. In the subsequent section, the dysregulated immune systems associated with aging are discussed, emphasizing the intricate landscape of the immune system during aging and its bidirectional relationship with neuroinflammation. Additionally, insights into the involvement of Myeloid-Derived Suppressor Cells (MDSCs) in Multiple Sclerosis (MS) pathogenesis are presented. The third section examines the role of microglia in neuroinflammation and various neurological diseases, including age-related macular degeneration (AMD) and Tuberculous Meningitis (TBM). Furthermore, the therapeutic potential of stem cell and extracellular vesicle-based therapies for stroke is explored, along with molecular mechanism of how inflammation regulates cerebral and myocardial ischemia. Finally, the importance of blood flow in maintaining vascular health and its impact on neurological disorders are discussed, highlighting the potential of novel assessment methods for optimizing patient care. Overall, this special issue offers valuable insights into the complex mechanisms underlying neurological disorders and identifies potential avenues for therapeutic intervention.

Exosome-mediated communication between gastric cancer cells and macrophages: implications for tumor microenvironment

Gastric cancer (GC) is a malignant neoplasm originating from the epithelial cells of the gastric mucosa. The pathogenesis of GC is intricately linked to the tumor microenvironment within which the cancer cells reside. Tumor-associated macrophages (TAMs) primarily differentiate from peripheral blood monocytes and can be broadly categorized into M1 and M2 subtypes. M2-type TAMs have been shown to promote tumor growth, tissue remodeling, and angiogenesis. Furthermore, they can actively suppress acquired immunity, leading to a poorer prognosis and reduced tolerance to chemotherapy. Exosomes, which contain a myriad of biologically active molecules including lipids, proteins, mRNA, and noncoding RNAs, have emerged as key mediators of communication between tumor cells and TAMs. The exchange of these molecules via exosomes can markedly influence the tumor microenvironment and consequently impact tumor progression. Recent studies have elucidated a correlation between TAMs and various clinicopathological parameters of GC, such as tumor size, differentiation, infiltration depth, lymph node metastasis, and TNM staging, highlighting the pivotal role of TAMs in GC development and metastasis. In this review, we aim to comprehensively examine the bidirectional communication between GC cells and TAMs, the implications of alterations in the tumor microenvironment on immune escape, invasion, and metastasis in GC, targeted therapeutic approaches for GC, and the efficacy of potential GC drug resistance strategies.

Endogenous Extracellular Vesicles Participate in Brain Remodeling after Ischemic Stroke

Brain remodeling after an ischemic stroke represents a promising avenue for exploring the cellular mechanisms of endogenous brain repair. A deeper understanding of these mechanisms is crucial for optimizing the safety and efficacy of neuroprotective treatments for stroke patients. Here, we interrogated the role of extracellular vesicles, particularly exosomes, as potential mediators of endogenous repair within the neurovascular unit (NVU). We hypothesized that these extracellular vesicles may play a role in achieving transient stroke neuroprotection. Using the established ischemic stroke model of middle cerebral artery occlusion in adult rats, we detected a surged in the extracellular vesicle marker CD63 in the peri-infarct area that either juxtaposed or co-localized with GFAP-positive glial cells, MAP2-labeled young neurons, and VEGF-marked angiogenic cells. This novel observation that CD63 exosomes spatially and temporally approximated glial activation, neurogenesis, and angiogenesis suggests that extracellular vesicles, especially exosomes, contribute to the endogenous repair of the NVU, warranting exploration of extracellular vesicle-based stroke therapeutics.