Mitochondria in Ischemic Stroke: New Insight and Implications

Targeting harmful effects of non-excitatory amino acids as an alternative therapeutic strategy to reduce ischemic damage

The involvement of the excitatory amino acids glutamate and aspartate in cerebral ischemia and excitotoxicity is well-documented. Nevertheless, the role of non-excitatory amino acids in brain damage following a stroke or brain trauma remains largely understudied. The release of amino acids by necrotic cells in the ischemic core may contribute to the expansion of the penumbra. Our findings indicated that the reversible loss of field excitatory postsynaptic potentials caused by transient hypoxia became irreversible when exposed to a mixture of just four non-excitatory amino acids (L-alanine, glycine, L-glutamine, and L-serine) at their plasma concentrations. These amino acids induce swelling in the somas of neurons and astrocytes during hypoxia, along with permanent dendritic damage mediated by N-methyl-D-aspartate receptors. Blocking N-methyl-D-aspartate receptors prevented neuronal damage in the presence of these amino acids during hypoxia. It is likely that astroglial swelling caused by the accumulation of these amino acids via the alanine-serine-cysteine transporter 2 exchanger and system N transporters activates volume-regulated anion channels, leading to the release of excitotoxins and subsequent neuronal damage through N-methyl-D-aspartate receptor activation. Thus, previously unrecognized mechanisms involving non-excitatory amino acids may contribute to the progression and expansion of brain injury in neurological emergencies such as stroke and traumatic brain injury. Understanding these pathways could highlight new therapeutic targets to mitigate brain injury.

A new specific GluN2B partial antagonist ameliorates brain injury caused by ischemic stroke in rats

Ischemic stroke is one of the top-ranked causes of death and disability in the world, but still lacking efficacy treatment options. Excitotoxicity caused by NMDA receptors (NMDARs) hyperactivation plays a key role in brain injury after ischemic stroke. GluN2B, the regulatory subunit of NMDARs, plays an important role in brain injury induced by ischemic stroke, and specific antagonists of GluN2B can ameliorate brain damage induced by ischemic stroke in rats. However, over half a century after Memantine (the first NMDA partial inhibitor for Alzheimer's clinical treatment) was identified, only a few additional NMDA partial inhibitors, especially those specifically targeting GluN2B, have been discovered. In this study, by using whole patch-clamp technique and multiple molecular biological methods, we discovered a new specific GluN2B partial antagonist, named FLY26, and further determined its effects on alleviating the brain injury caused by ischemic stroke in rats. Our experiment results showed FLY26 suppressed the excitotoxicity caused by overactivation of NMDARs in SH-SY5Y cells, and ameliorated brain damage of middle cerebral artery occlusion (MACO) rats, within the dosage range of 1.5-6.0 mg/kg, via BDNF/TrkB signaling pathway. Our results indicated that FLY26 is a promising lead compound for the development of novel, specific GluN2B partial antagonist. Our results indicated that FLY26 is a promising lead compound for the development of novel, specific GluN2B partial antagonist, which may offer better safety profile as a therapeutic intervention for ischemic stroke.

Apolipoproteins in ischemic stroke progression and recovery: Key molecular mechanisms and therapeutic potential

Ischemic stroke, responsible for 80 % of all strokes, is a leading cause of mortality globally. While altered lipids profiles are recognized as modifiable risk factors, their direct impact on stroke outcomes is less understood due to the brain's distinct lipid metabolism and the selective permeability of the blood-brain barrier for lipoproteins. As key components of lipoproteins, apolipoproteins are essential for lipid transport, redistribution and metabolism in both the central nervous system and peripheral blood circulation. This review provides an updated perspective on the influence of brain-expressed apolipoproteins (such as ApoE, ApoA-I, ApoJ, ApoD, and others) and those that cross the damaged blood-brain barrier following ischemic stroke. We explore hypotheses regarding their involvement in molecular pathways related to lipid metabolism, inflammation, oxidative stress, mitochondrial function and blood-brain barrier integrity. Through this synthesis, we aim to identify potential biomarkers and therapeutic targets, thereby enhancing our understanding of apolipoproteins in ischemic stroke progression and contributing to improved clinical outcomes.

Acute pancreatitis experimental models, advantages and disadvantages

Acute pancreatitis represents a severe health problem, not only because of the number of people affected but also because of the severity of its clinical presentation that can eventually lead to the death of patients. The study of the disease is complex, and we lack optimized models that can approach the clinical presentation in patients, in addition to the significant vulnerability of the organ itself. In the present work, we undertook the task of reviewing and analyzing the experimental methods most currently used for the induction of acute pancreatitis, emphasizing the advantages and disadvantages of each model and their delimitation based on experimental objectives. We aimed to provide an actual and quick-access guide for researchers interested in experimental acute pancreatitis.

Benfotiamine, a Lipid-Soluble Derivative of Vitamin B1, Ameliorates the Carbohydrate Overload-Induced Mitochondrial Dysfunction in Fish Megalobrama amblycephala by Triggering the ULK1-Mediated Mitophagy

Compared with mammals, fish have a limited capability to utilize carbohydrates, thus generally suffering from metabolic disorders when offered carbohydrate-enriched diets. As a synthetic liposoluble derivative of vitamin B1, benfotiamine can alleviate the carbohydrate overload-induced mitochondrial dysfunction in fish, but the potential mechanisms have not been well explored. The present research was performed to unveil the molecular pathways through which benfotiamine benefits the mitochondrial function of a carp species Megalobrama amblycephala, which often exhibits metabolic disturbances. First, a control (C, 30% carbohydrate) group, a high-carbohydrate (HC, 43% carbohydrate) group, and a HC incorporating benfotiamine (1.425 mg/kg) group were conducted, respectively, in a 12-week feeding trial. Then, two in vitro studies were performed by using primary hepatocytes. In the first one, a media treatment, a high-glucose (HG) treatment, and a HG incorporating benfotiamine were designated, respectively. In the second one, a media group, a vehicle group, a HG group, and a HG + BL-918 (the agonist of UNC-51-like kinase 1 [ULK1]) group were adopted, respectively. The results indicated that HC/HG treatment resulted in mitophagy disorder by downregulating the phosphorylation of AMPK and ULK1 and the contents of proteins involved in the PTEN-induced putative kinase protein 1 (PINK1)-Parkin pathway. Mitochondrial dysfunction was also observed, as was indicative of the reduced activities of mitochondrial complex I, III, and SDH. However, benfotiamine treatment increased the contents of P-AMPK, P-ULK1, and the PINK1-Parkin pathway-related proteins as well as mitochondrial complex activities. In conclusion, benfotiamine could trigger the ULK1-mediated mitophagy to ameliorate the carbohydrate overload-induced mitochondrial dysfunction in fish.

Astrocyte-neuron metabolic crosstalk in ischaemic stroke

Ischemic stroke (IS) is caused by temporary or permanent obstruction of the brain's blood supply. The disruption in glucose and oxygen delivery that results from the drop in blood flow impairs energy metabolism. A significant pathological feature of IS impaired energy metabolism. Astrocytes, as the most prevalent glial cells in the brain, sit in between neurons and the microvasculature. By taking advantage of their special anatomical location, they play a crucial part in regulating cerebral blood flow (CBF) and metabolism. Astrocytes can withstand hypoxic and ischemic conditions better than neurons do. Additionally, astrocytes are essential for maintaining the metabolism and function of neurons. Therefore, the "neurocentric" perspective on neuroenergetics is gradually giving way to a more comprehensive perspective that takes into account metabolic interaction between astrocytes and neurons. Since neurons in the core region of the infarct are unable to undergo oxidative metabolism, the focus of attention in this review is on neurons in the peri-infarct region. We'll go over the metabolic crosstalk of astrocytes and neurons during the acute phase of IS using three different types of metabolites: lactate, fatty acids (FAs), and amino acids, as well as the mitochondria. After IS, astrocytes in the peri-infarct zone can produce lactate, ketone bodies (KBs), glutamine (Gln), and l-serine, shuttling these metabolites, along with mitochondria, to neurons. This process helps maintain the energy requirements of neurons, preserves their redox state, and regulates neurotransmitter receptor activity.

SFXN1 Reduction Alleviates Cerebral Ischemia-Reperfusion Injury by Promoting Neuronal Survival and Reducing Neuroinflammation

AIM

Sideroflexin 1 (SFXN1) is an important inner mitochondrial membrane protein that regulates many physiological and pathological events. However, the role of SFXN1 in cerebral ischemia-reperfusion (I/R)-induced neuronal death remains unclear.

METHODS

We employed in vivo injury models of transient middle cerebral artery occlusion (tMCAO) and in vitro models of lipopolysaccharide (LPS) stimulation and oxygen-glucose deprivation/reperfusion (OGD/R) to investigate the regulatory effects of SFXN1 on neuroinflammation and brain injury. Western blotting, immunofluorescence, and real-time quantitative PCR were utilized to assess SFXN1 expression, proinflammatory signaling pathways activation, and cytokine levels in vitro. Cerebral infarction was evaluated using 2,3,5-triphenyltetrazolium chloride (TTC) staining and Nissl staining.

RESULTS

SFXN1 expression was upregulated following cerebral I/R injury. Both neurons and microglia exhibited increased SFXN1 expression after oxygen-glucose deprivation/reoxygenation (OGD/R) treatment. SFXN1 knockdown reduced OGD/R-induced neuronal death and alleviated cerebral I/R injury. Additionally, conditioned medium from SFXN1-knockdown microglia reduced neurotoxicity in vitro. Mechanistically, SFXN1 induced mitochondrial dysfunction and neuronal death after OGD/R in an iron-independent manner. Furthermore, SFXN1 promoted the production of proinflammatory cytokines by promoting NF-κB activation, partially through iron transport in microglia after OGD/R.

CONCLUSION

This study reveals the novel role of SFXN1 in exacerbating cerebral I/R injury by reducing neuronal survival through the modulation of mitochondrial function and promotion of microglia-mediated neuroinflammation via NF-κB activation.

Identification of Mitochondrial and Succinylation Modification-Related Gene Signature in Ischemic Stroke

Ischemic stroke (IS) is a leading cause of death and disability worldwide, often associated with immune dysregulation, mitochondrial dysfunction, and altered protein succinylation. This study aimed to identify mitochondrial and succinylation-related gene signatures with diagnostic potential in IS. Differentially expressed genes (DEGs) associated with IS were identified using transcriptome expression profiles from merged GSE16561 and GSE58294 GEO datasets. Functional enrichment and WGCNA identified hub genes. Mitochondrial and succinylation-related gene expression was assessed via ssGSEA. Feature genes were selected using machine learning. A prognostic nomogram was constructed. PPI networks were generated using GeneMANIA. Immune infiltration was assessed through ssGSEA. Drug-gene interactions were explored using DGIdb. qRT-PCR validation was performed on blood samples from IS patients and controls. We identified 317 DEGs enriched in immune response and inflammation pathways in 108 IS patients and 47 healthy controls using data from the merged datasets. WGCNA identified 101 hub genes in the yellow module and 65 in the brown module. Seven overlapping genes related to mitochondrial and succinylation processes were identified. Feature gene analysis revealed six key genes (MRPL41, NGRN, SLC25A42, SPTLC2, TUBB, and TXN) with robust diagnostic potential across both the merged and individual datasets (all AUCs > 0.7). Nomogram integration demonstrated predictive reliability. Feature genes exhibited significant correlations with immune cell infiltration. qRT-PCR validation confirmed the differential expression of four feature genes. TUBB and TXN showed interactions with various drugs. Mitochondrial and succinylation-related genes have diagnostic significance in IS, providing insights into disease pathogenesis and clinical applications.

Integrative bioinformatics analysis reveals mitochondrial-Immune crosstalk in depression and stroke: a multi-omics mechanistic exploration

Stroke, a leading cause of disability and mortality globally, often cooccurs with depression or poststroke depression (PSD). The intricate interplay between mitochondrial metabolism and immune-related inflammation in depression and stroke remains a pivotal yet unresolved area. This study harnessed bioinformatics to elucidate the distinct contributions of mitochondrial metabolism and the immune microenvironment, as well as their complex interactions, to the pathogenesis of depression and stroke. By analyzing gene expression profiles from depression and stroke datasets alongside mitochondrial gene data, differentially expressed genes (DEGs) were meticulously identified, with a particular focus on mitochondria-related DEGs (MitoDEGs). Comprehensive functional investigations of common DEGs were conducted through Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. A robust protein-protein interaction (PPI) network was constructed, pinpointing ten hub-MitoDEGs intricately linked to depression and stroke. Furthermore, leveraging single-cell RNA sequencing analysis has shed light on gene expression across a myriad of cell types. Notably, these findings demonstrated immune cell dysregulation, revealing significant alterations in neutrophil and CD8+ T-cell infiltration within both the depression and stroke contexts. Correlation analyses revealed profound associations of the hub-MitoDEGs with mitochondrial metabolism, immune-related genes, and immunocytes. Importantly, this study also delineated ten potential drugs that target key genes implicated in depression and stroke, identifying promising avenues for innovative therapeutic interventions in these debilitating disorders.

Embryonic 6:2 Fluorotelomer Alcohol Exposure Disrupts the Blood‒Brain Barrier by Causing Endothelial‒to‒Mesenchymal Transition in the Male Mice

6:2 Fluorotelomer alcohol (6:2 FTOH) is a raw material used in the manufacture of short-chain poly- and perfluoroalkyl substances. Our previous study revealed that gestational exposure to 6:2 FTOH can impair blood‒brain barrier (BBB) function in offspring, accompanied by anxiety-like behavior and learning memory deficits. The aim of this study was to further investigate the specific mechanism by which maternal exposure to 6:2 FTOH resulted in impaired BBB function in offspring mice. Pregnant mice were orally administered different doses of 6:2 FTOH (0, 5, 25, and 125 mg/kg/day) from gestation day 8.5 until delivery. These results confirmed that maternal 6:2 FTOH exposure impaired BBB function and disrupted the brain immune microenvironment. Subsequent investigations revealed that endothelial-to-mesenchymal transition (EndMT) in the cerebral microvascular endothelium of offspring may be the mechanism mediating functional disruption of the BBB. Mechanistic studies revealed that exposure to 6:2 FTOH upregulated ETS proto-oncogene 1 (ETS1) expression via the tumor necrosis factor-α/extracellular signal-regulated kinase 1/2 signaling pathway, which mediated disturbances in energy metabolism, leading to impaired actin dynamics and subsequently triggering the EndMT phenotype. This is the first finding indicating that gestational 6:2 FTOH exposure caused functional impairment of the BBB through ETS1-mediated EndMT in cerebral microvascular endothelial cells, potentially providing novel insight into the environmental origins of neurodevelopmental disorders.

Neuroprotective potential of ApoE-mimetic peptide (ApoEFrag) in stroke models: Neurobehavioural and mechanistic study

Stroke is the second leading cause of death worldwide, and currently, there is no effective neuroprotective agent available for its treatment. Though apolipoprotein E (ApoE) showed potential as a neuroprotective agent for CNS disorders, however, its large size limits its clinical application. To overcome this issue, smaller ApoE-mimetic peptides that mimic the biological functions of ApoE have been developed. In this study, we designed and characterized a novel ApoE-mimetic peptide, ApoEFrag, and explored its neuroprotective potential in experimental stroke models. ApoEFrag was evaluated for its ability to interact with oxidized lipids and lack of self-aggregation potential. In the in vitro cerebral ischemia model, ApoEFrag demonstrated neuroprotection against glutamate-induced neuronal damage in SH-SY5Y cells by maintaining mitochondrial health and reducing reactive oxygen species (ROS) levels. To confirm ApoEFrag's neuroprotective potential, ApoEFrag was investigated in middle cerebral artery occlusion (MCAO) induced ischemic stroke in rats. ApoEFrag administration significantly reduced infarct size, improved neurological function, and lowered mortality. ApoEFrag exhibited anti-inflammatory effects, reduced astrocyte activation and apoptosis, and promoted neurogenesis. Overall, ApoEFrag shows promising neuroprotective effects and could be a potential therapeutic approach for the treatment of stroke.

Disruption of the Pum2 axis Aggravates neuronal damage following cerebral Ischemia-Reperfusion in mice

Stroke remains a leading cause of disability and mortality worldwide, with mitochondrial dysfunction closely linked to ischemic injury. This study explores the Norad-Pum2-Mff axis as a key regulator of mitochondrial function following ischemia-reperfusion (I/R) injury. Using an oxygen-glucose deprivation/reoxygenation (OGD/R) model, Mff protein levels were significantly elevated post-OGD/R, while mRNA levels remained unchanged, suggesting post-transcriptional regulation. Pumilio2 (Pum2), an RNA-binding protein, was shown to inhibit Mff translation, while Norad, a long non-coding RNA, sequestered Pum2, alleviating this inhibition. We observed decreased Pum2 levels and binding capacity to Mff mRNA, alongside increased Norad levels and binding to Pum2 in neurons after OGD/R. Overexpression of Pum2 in neurons reduced Mff levels, mitigated mitochondrial fragmentation, and alleviated neuronal injury. In a mouse model of middle cerebral artery occlusion/reperfusion (MCAO/R), Pum2 overexpression further improved mitochondrial morphology, reduced infarct volume, and enhanced neurobehavioral recovery. These findings suggest that targeting the Norad-Pum2-Mff axis could provide a promising therapeutic strategy for ischemic stroke by restoring mitochondrial function and reducing neuronal damage.

Novel high-content and open-source image analysis tools for profiling mitochondrial morphology in neurological cell models

Mitochondria undergo dynamic morphological changes depending on cellular cues, stress, genetic factors, or disease. The structural complexity and disease-relevance of mitochondria have stimulated efforts to generate image analysis tools for describing mitochondrial morphology for therapeutic development. Using high-content analysis, we measured multiple morphological parameters and employed unbiased feature clustering to identify the most robust pair of texture metrics that described mitochondrial state. Here, we introduce a novel image analysis pipeline to enable rapid and accurate profiling of mitochondrial morphology in various cell types and pharmacological perturbations. We applied a high-content adapted implementation of our tool, MitoProfilerHC, to quantify mitochondrial morphology changes in i) a mammalian cell dose response study and ii) compartment-specific drug effects in primary neurons. Next, we expanded the usability of our pipeline by using napari, a Python-powered image analysis tool, to build an open-source version of MitoProfiler and validated its performance and applicability. In conclusion, we introduce MitoProfiler as both a high-content-based and an open-source method to accurately quantify mitochondrial morphology in cells, which we anticipate to greatly facilitate mechanistic discoveries in mitochondrial biology and disease.

Labeling and isolating cell specific neuronal mitochondria and their functional analysis in mice post stroke

Dendritic and axonal plasticity, which mediates neurobiological recovery after a stroke, critically depends on the mitochondrial function of neurons. To investigate, in vivo, neuronal mitochondrial function at the stroke recovery stage, we employed Mito-tag mice combined with cerebral cortical infection of AAV9 produced from plasmids carrying Cre-recombinase controlled by two neuronal promoters, synapsin-I (SYN1) and calmodulin-kinase IIa to induce expression of a hemagglutinin (HA)-tagged enhanced green fluorescence protein (EGFP) that localizes to mitochondrial outer membranes of SYN1 positive (SYN+) and CaMKIIa positive (CaMKIIa+) neurons. These mice were then subjected to permanent middle cerebral artery occlusion (MCAO) and sacrificed 14 days post stroke. Neuronal mitochondria were then selectively isolated from the fresh brain tissues excised from the ischemic core (IC), ischemic boundary zone (IBZ), as well as from the homologous contralateral hemisphere (CON) by anti-HA magnetic beads for functional analyses. We found that the bead pulled neuronal specific mitochondria were co-precipitated with GFP and enriched with mitochondrial markers, e.g. voltage-dependent anion channel, cytochrome C, and COX IV, but lacked the Golgi protein RCAS1 as well as endoplasmic reticulum markers: Heme‑oxygenase 1 and Calnexin, indicating that specific neuronal mitochondria have been selectively isolated. Western-blot data showed that oxidative phosphorylation (OXPHOS) components in SYN+ and CAMKII+ neuronal mitochondria were significantly decreased in the IBZ and further decreased in the IC compared to the contralateral tissue, which was associated with the significant reductions of mitochondrial function indicated by oxygen consumption rate (OCR) (p < 0.05, respectively, for both neuron types). These data suggest dysfunction of neuronal mitochondria post stroke is present during the stroke recovery stage. Collectively, for the first time, we demonstrated that using a Mito-tag mouse line combined with AAV9 carrying Cre recombinase approach, neuronal specific mitochondria can be efficiently isolated from the mouse brain to investigate their functional changes post stroke.

Naotaifang formula regulates Drp1-induced remodeling of mitochondrial dynamics following cerebral ischemia-reperfusion injury

Cerebral ischemia-reperfusion injury (CIRI) has emerged as a hindrance for rehabilitation of ischemic stroke patients. Naotaifang (NTF) exhibits beneficial efficacy in alleviating inflammation and ferroptosis in vitro during CIRI. While the potential role of NTF in regulating mitochondrial dynamics in CIRI are not elucidated. This study aimed to explore the mechanism of NTF against CIRI by regulating the dynamin-related protein 1 (Drp1)-dependent mitochondrial fission/fusion. Modeling middle cerebral artery occlusion/reperfusion (MCAO/R) in vivo to evaluate the effects of NTF on the MCAO/R-damaged neurons and the structure, dynamics and function of mitochondria. An oxygen-glucose deprivation/reperfusion (OGD/R) cell model was established to evaluate the role of NTF in OGD/R-damaged cells. Function of Drp1 in CIRI and the neuroprotection of NTF through the mitochondrial fission/fusion pathway were investigated in vivo and in vitro. The results revealed that in vivo, NTF alleviated neuron injury in a dose-dependent manner, down-regulated Drp1 and fission protein 1 (Fis1) levels, upregulated optic atrophy 1 (Opa1), mitofusin 1/2 (Mfn1 and Mfn2), facilitated mitochondrial fusion and inhibited mitochondrial fission to rescue cells from CIRI. In vitro, Drp1 overexpression inhibited mitochondrial fusion and activated mitochondrial fission, while silencing of Drp1 exhibited the opposite result. NTF rebalanced mitochondrial dynamic in the OGD/R cell model. NTF could alleviate neuron injury following CIRI by regulating the balance of mitochondrial fission and fusion. Targeting Drp1-dependent mitochondrial dynamics may represent a viable treatment strategy for addressing the issues of CIRI post ischemic stroke.

Mitigating mitochondrial dysfunction and neuroinflammation by hematoma aspiration in a new surgical model for severe intracerebral hemorrhage

BACKGROUND

Intracerebral hemorrhage (ICH) is associated with a large hematoma that causes compression, increased intracranial pressure (IICP), midline shift, and brain herniation, and may ultimately lead to death. Urgent surgical removal of the large hematoma can ameliorate these injuries, which would be life-saving, but has not improved clinical outcome. A suitable animal model that mimics the clinically relevant human severe ICH injury requiring surgical hematoma evacuation is urgently needed. Here, we established a novel model of severe ICH in rats allowing aspiration of the hematoma and studying the effects of mitochondrial dysfunction in ICH.

METHODS

Severe ICH was induced by intra-striatal injection of 0.6 U of collagenase in 3 μL sterile saline over 15 min. Aspiration of approximately 75 % of the total hematoma was performed 6 h after induction of severe ICH. The effects of hematoma aspiration on hematoma volume, mortality, oxidative stress, ATP levels, mitochondrial dysfunction, and neurological function were measured in rats.

RESULTS

Severe ICH induction increased hematoma volume, neurological deficits, and mortality. Hematoma aspiration abolished mortality and significantly reduced hematoma volume, and neurological deficits. In addition, hematoma aspiration ameliorated the pronounced mitochondrial dysfunction responsible for the failure of energy production and excessive oxidative stress associated with severe hemorrhagic injury. Hematoma aspiration also modulated mitochondrial biogenesis and mitophagy, thereby promoting mitochondrial homeostasis. Markers of neuroinflammation, including iNOS, MMP9, and MPO, were elevated in severe ICH but attenuated by hematoma aspiration.

CONCLUSION

This study established an animal model of severe ICH and provides valuable insights into the complex pathogenesis of severe ICH. The results showed that hematoma aspiration effectively ameliorates mitochondrial dysfunction, oxidative stress, and neuroinflammation, highlighting its potential as a therapeutic intervention.

Enhanced Small Extracellular Vesicle Uptake by Activated Interneurons Improves Stroke Recovery in Mice

Neuronal circuitry remodelling, which comprises excitatory and inhibitory neurons, is critical for improving neurological outcomes after a stroke. Preclinical studies have shown that small extracellular vesicles (sEVs) have a therapeutic effect on stroke recovery. However, it is highly challenging to use sEVs to specifically target individual neuronal populations to enhance neuronal circuitry remodelling after stroke. In the present study, using a chemogenetic approach to specifically activate peri-infarct cortical interneurons in combination with the administration of sEVs derived from cerebral endothelial cells (CEC-sEVs), we showed that the CEC-sEVs were preferentially taken up by the activated neurons, leading to significant improvement of functional outcome after stroke, which was associated with augmentation of peri-infarct cortical axonal/dendritic outgrowth and of axonal remodelling of the corticospinal tract. The ultrastructural and Western blot analyses revealed that neurons with internalization of CEC-sEVs exhibited significantly reduced numbers of damaged mitochondria and proteins that mediate dysfunctional mitochondria, respectively. Together, these data indicate that the augmented uptake of CEC-sEVs by activated peri-infarct cortical interneurons facilitates neuronal circuitry remodelling and functional recovery after stroke, which has the potential to be a novel therapy for improving stroke recovery.

The fourth family in the world with a novel variant in the ATP5MK gene: four siblings with complex V (ATP synthase) deficiency

Mitochondrial Complex V (ATP synthase) deficiency nuclear type 6 (MC5DN6) is a progressive neurodegenerative disorder characterized by autosomal recessive inheritance and developmental regression, particularly in gross motor skills, which manifests in early childhood. This study aims to present the discovery of a novel variant in four male siblings aged 13 years 9 months to 25 years, making this the fourth family reported globally, while also raising awareness of rare mitochondrial diseases. Four individuals from the same family were retrospectively evaluated based on their demographic, clinical, laboratory, and molecular genetic data. The mutation in the ATP5MK gene was analyzed using the exome sequencing (ES) method. The detected variation was classified according to the criteria American College of Medical Genetics. Four cases, aged between 13 years 9 months and 25 years, were analyzed. All individuals were male. While all four cases had a history of neurodegenerative disease, they also exhibited intellectual disability, muscle weakness, increased deep tendon reflexes in the lower extremities, spasticity, scoliosis, pes cavus deformity, positive Babinski reflex, abnormal gait patterns due to foot deformities, and normal cerebellar tests. Additional findings included geographic tongue (n = 2), strabismus (n = 2), nystagmus (n = 1), ophthalmoplegia (n = 2), hypertrophic upper extremity muscle body build (n = 2), keloid tissue (n = 1), and short stature (n = 3). ES of the first case identified a homozygous splice donor variant (c.87 + 1G > A) in the ATP5MK gene as a novel variant, and family screening revealed the same variant in a biallelic state in the other three siblings. The parents were confirmed as heterozygous carriers, consistent with autosomal recessive inheritance. Mitochondrial diseases can mimic a wide range of neurological disorders. They should be considered as a potential underlying cause when treatment for suspected differential diagnoses proves ineffective.

Differential Protective Effects of Edaravone in Cerebellar and Hippocampal Ischemic Injury Models

Ischemic stroke is a leading cause of mortality and disability, with cerebellar strokes posing severe complications such as herniation and brainstem compression. Edaravone, a radical scavenger known for reducing oxidative stress, has shown neuroprotective effects in cerebral strokes, but its impact on cerebellar strokes remains unclear. This study investigates Edaravone's protective properties in organotypic slice cultures of rat cerebellum and hippocampus, employing an oxygen-glucose deprivation (OGD) model to simulate ischemic stroke. The hippocampus served as comparative structure due to its high hypoxia sensitivity. Our results confirmed effective hypoxic induction with increases in HIF-1α and HIF-2α expression. Edaravone significantly reduced lactate dehydrogenase (LDH) levels, indicating diminished cellular damage, with cerebellar tissues showing greater vulnerability. Additionally, Edaravone reduced reactive oxygen species (ROS) in both tissues, though its efficacy may be limited by higher oxidative stress in cerebellar cultures. Seahorse XF analysis revealed that Edaravone preserved mitochondrial respiration and tissue integrity in cerebellar and hippocampal slice cultures. However, Edaravone was more effective in preserving mitochondrial respiration in hippocampal slices, suggesting that OGD-induced damage is more severe in cerebellar tissue. In conclusion, Edaravone demonstrates significant cell protective effects in both cerebellar and hippocampal tissues under OGD conditions, preserving tissue integrity and enhancing mitochondrial function in a tissue-dependent manner. These findings suggest Edaravone as a promising therapeutic candidate for cerebellar stroke. Further in vivo studies are required to assess its full clinical potential.

Pyrroloquinoline quinone: a potential neuroprotective compound for neurodegenerative diseases targeting metabolism

Pyrroloquinoline quinone is a quinone described as a cofactor for many bacterial dehydrogenases and is reported to exert an effect on metabolism in mammalian cells/tissues. Pyrroloquinoline quinone is present in the diet being available in foodstuffs, conferring the potential of this compound to be supplemented by dietary administration. Pyrroloquinoline quinone's nutritional role in mammalian health is supported by the extensive deficits in reproduction, growth, and immunity resulting from the dietary absence of pyrroloquinoline quinone, and as such, pyrroloquinoline quinone has been considered as a "new vitamin." Although the classification of pyrroloquinoline quinone as a vitamin needs to be properly established, the wide range of benefits for health provided has been reported in many studies. In this respect, pyrroloquinoline quinone seems to be particularly involved in regulating cell signaling pathways that promote metabolic and mitochondrial processes in many experimental contexts, thus dictating the rationale to consider pyrroloquinoline quinone as a vital compound for mammalian life. Through the regulation of different metabolic mechanisms, pyrroloquinoline quinone may improve clinical deficits where dysfunctional metabolism and mitochondrial activity contribute to induce cell damage and death. Pyrroloquinoline quinone has been demonstrated to have neuroprotective properties in different experimental models of neurodegeneration, although the link between pyrroloquinoline quinone-promoted metabolism and improved neuronal viability in some of such contexts is still to be fully elucidated. Here, we review the general properties of pyrroloquinoline quinone and its capacity to modulate metabolic and mitochondrial mechanisms in physiological contexts. In addition, we analyze the neuroprotective properties of pyrroloquinoline quinone in different neurodegenerative conditions and consider future perspectives for pyrroloquinoline quinone's potential in health and disease.

Zhongfeng Xingnao Liquid ameliorates post-stroke cognitive impairment through sirtuin1 (SIRT1)/nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase 1 (HO-1) pathway

The activation of the sirtuin1 (SIRT1)/nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase 1 (HO-1) pathway has been shown to mitigate oxidative stress-induced apoptosis and mitochondrial damage by reducing reactive oxygen species (ROS) levels. Clinical trials have demonstrated that Zhongfeng Xingnao Liquid (ZFXN) ameliorates post-stroke cognitive impairment (PSCI). However, the underlying mechanism, particularly whether it involves protecting mitochondria and inhibiting apoptosis through the SIRT1/Nrf2/HO-1 pathway, remains unclear. This study employed an oxygen-glucose deprivation (OGD) cell model using SH-SY5Y cells and induced PSCI in rats through modified bilateral carotid artery ligation (2VO). The effects of ZFXN on learning and memory, neuroprotective activity, mitochondrial function, oxidative stress, and the SIRT1/Nrf2/HO-1 pathway were evaluated both in vivo and in vitro. Results indicated that ZFXN significantly increased the B-cell lymphoma 2 (Bcl2)/Bcl2-associated X (Bax) ratio, reduced terminal deoxynucleotidyl transferase-mediated dUTP nick-end-labeling (TUNEL)+ cells, and markedly improved cognition, synaptic plasticity, and neuronal function in the hippocampus and cortex. Furthermore, ZFXN exhibited potent antioxidant activity, evidenced by decreased ROS and malondialdehyde (MDA) content and increased superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH) levels. ZFXN also demonstrated considerable enhancement of mitochondrial membrane potential (MMP), Tom20 fluorescence intensity, adenosine triphosphate (ATP) and energy charge (EC) levels, and mitochondrial complex I and III activity, thereby inhibiting mitochondrial damage. Additionally, ZFXN significantly increased SIRT1 activity and elevated SIRT1, nuclear Nrf2, and HO-1 levels. Notably, these effects were substantially counteracted when SIRT1 was suppressed by the inhibitor EX-527 in vitro. In conclusion, ZFXN alleviates PSCI by activating the SIRT1/Nrf2/HO-1 pathway and preventing mitochondrial damage.

Targeting mitochondrial transfer: a new horizon in cardiovascular disease treatment

Cardiovascular diseases (CVDs) are the leading cause of mortality among individuals with noncommunicable diseases worldwide. Obesity is associated with an increased risk of developing cardiovascular disease (CVD). Mitochondria are integral to the cardiovascular system, and it has been reported that mitochondrial transfer is associated with the pathogenesis of multiple CVDs and obesity. This review offers a comprehensive examination of the relevance of mitochondrial transfer to cardiovascular health and disease, emphasizing the critical functions of mitochondria in energy metabolism and signal transduction within the cardiovascular system. This highlights how disruptions in mitochondrial transfer contribute to various CVDs, such as myocardial infarction, cardiomyopathies, and hypertension. Additionally, we provide an overview of the molecular mechanisms governing mitochondrial transfer and its potential implications for CVD treatment. This finding underscores the therapeutic potential of mitochondrial transfer and addresses the various mechanisms and challenges in its implementation. By delving into mitochondrial transfer and its targeted modulation, this review aims to advance our understanding of cardiovascular disease treatment, presenting new insights and potential therapeutic strategies in this evolving field.

Inter- and intracellular mitochondrial communication: signaling hubs in aging and age-related diseases

Mitochondria are versatile and complex organelles that can continuously communicate and interact with the cellular milieu. Deregulated communication between mitochondria and host cells/organelles has significant consequences and is an underlying factor of many pathophysiological conditions, including the process of aging. During aging, mitochondria lose function, and mitocellular communication pathways break down; mitochondrial dysfunction interacts with mitochondrial dyscommunication, forming a vicious circle. Therefore, strategies to protect mitochondrial function and promote effective communication of mitochondria can increase healthy lifespan and longevity, which might be a new treatment paradigm for age-related disorders. In this review, we comprehensively discuss the signal transduction mechanisms of inter- and intracellular mitochondrial communication, as well as the interactions between mitochondrial communication and the hallmarks of aging. This review emphasizes the indispensable position of inter- and intracellular mitochondrial communication in the aging process of organisms, which is crucial as the cellular signaling hubs. In addition, we also specifically focus on the status of mitochondria-targeted interventions to provide potential therapeutic targets for age-related diseases.

SIRT-1/RHOT-1/PGC-1α loop modulates mitochondrial biogenesis and transfer to offer resilience following endovascular stem cell therapy in ischemic stroke

Current clinical interventions for stroke majorly involve thrombolysis or thrombectomy, however, cessation of the progressive deleterious cellular cascades post-stroke and long-term neuroprotection are yet to be explored. Mitochondria are highly vulnerable organelles and their dysfunction is one of the detrimental consequences following stroke. Mitochondria dysregulation activate unfavourable cellular events over a period of time that leads to the collapse of neuronal machinery in the brain. Hence, strategies to protect and replenish mitochondria in injured neurons may be useful and needs to be explored. Stem cell therapy in ischemic stroke holds a great promise. Past studies have shown beneficial outcomes of endovascularly delivered stem cells in both pre-clinical and clinical settings. Intra-arterial (IA) administration can provide more cells to the stroke foci and affected brain regions than intravenous administration. Supplying new mitochondria to the stroke-compromised neurons either in the core or penumbra by infused stem cells can help increase their survival and longevity. Previously, our lab has demonstrated that IA 1∗105 mesenchymal stem cells (MSCs) in rats were safe, efficacious and rendered neuroprotection by regulating neuronal calcineurin, modulating sirtuin1(SIRT-1) mediated inflammasome signaling, ameliorating endoplasmic reticulum-stress, alleviation of post-stroke edema and reducing cellular apoptosis. To explore further, our present study aims to investigate the potential of IA MSCs in protecting and replenishing mitochondria in the injured neurons post-stroke and the involvement of SIRT-1/RHOT-1/PGC-1α loop towards mitochondria transfer, biogenesis, and neuroprotection. This study will open new avenues for using stem cells for ischemic stroke in clinics as one of the future adjunctive therapies.

A rotenone organotypic whole hemisphere slice model of mitochondrial abnormalities in the neonatal brain

Mitochondrial abnormalities underscore a variety of neurologic injuries and diseases and are well-studied in adult populations. Clinical studies identify critical roles of mitochondria in a wide range of developmental brain injuries, but models that capture mitochondrial abnormalities in systems representative of the neonatal brain environment are lacking. Here, we develop an organotypic whole-hemisphere (OWH) brain slice model of mitochondrial dysfunction in the neonatal brain. We extended the utility of complex I inhibitor rotenone (ROT), canonically used in models of adult neurodegenerative diseases, to inflict mitochondrial damage in OWH slices from term-equivalent rats. We quantified whole-slice health over 6 days of exposure for a range of doses represented in ROT literature. We identified 50 nM ROT as a suitable exposure level for OWH slices to inflict injury without compromising viability. At the selected exposure level, we confirmed exposure- and time-dependent mitochondrial responses showing differences in mitochondrial fluorescence and nuclear localization using MitoTracker imaging in live OWH slices and dysregulated mitochondrial markers via RT-qPCR screening. We leveraged the regional structures present in OWH slices to quantify cell density and cell death in the cortex and the midbrain regions, observing higher susceptibilities to damage in the midbrain as a function of exposure and culture time. We supplemented these findings with analysis of microglia and mature neurons showing time-, region-, and exposure-dependent differences in microglial responses. We demonstrated changes in tissue microstructure as a function of region, culture time, and exposure level using live-video epifluorescence microscopy of extracellularly diffusing nanoparticle probes in live OWH slices. Our results highlight severity-, time-, and region-dependent responses and establish a complimentary model system of mitochondrial abnormalities for high-throughput or live-tissue experimental needs.

The Influence of Oxidative Stress Markers in Patients with Ischemic Stroke

Stroke is the second leading cause of death worldwide, and its incidence is rising rapidly. Acute ischemic stroke is a subtype of stroke that accounts for the majority of stroke cases and has a high mortality rate. An effective treatment for stroke is to minimize damage to the brain's neural tissue by restoring blood flow to decreased perfusion areas of the brain. Many reports have concluded that both oxidative stress and excitotoxicity are the main pathological processes associated with ischemic stroke. Current measures to protect the brain against serious damage caused by stroke are insufficient. For this reason, it is important to investigate oxidative and antioxidant strategies to reduce oxidative damage. This review focuses on studies assessing the concentration of oxidative stress biomarkers and the level of antioxidants (enzymatic and non-enzymatic) and their impact on the clinical prognosis of patients after stroke. Mechanisms related to the production of ROS/RNS and the role of oxidative stress in the pathogenesis of ischemic stroke are presented, as well as new therapeutic strategies aimed at reducing the effects of ischemia and reperfusion.

Mitochondria-containing extracellular vesicles from mouse vs. human brain endothelial cells for ischemic stroke therapy

Ischemic stroke-induced mitochondrial dysfunction in the blood-brain barrier-forming brain endothelial cells (BECs) results in long-term neurological dysfunction post-stroke. We previously reported data from a pilot study where intravenous administration of human BEC (hBEC)-derived mitochondria-containing extracellular vesicles (EVs) showed a potential efficacy signal in a mouse middle cerebral artery occlusion (MCAo) model of stroke. We hypothesized that EVs harvested from donor species homologous to the recipient species (e.g., mouse) may improve therapeutic efficacy, and therefore, use of mouse BEC (mBEC)-derived EVs may improve post-stroke outcomes in MCAo mice. We investigated potential differences in the mitochondria transfer of EVs derived from the same species as the recipient cell (mBEC-EVs and recipient mBECs or hBECs-EVs and recipient hBECs) vs. cross-species EVs and recipient cells (mBEC-EVs and recipient hBECs or vice versa). Our results showed that while both hBEC- and mBEC-EVs transferred EV mitochondria, mBEC-EVs outperformed hBEC-EVs in increasing ATP levels and improved recipient mBEC mitochondrial function via increasing oxygen consumption rates. mBEC-EVs significantly reduced brain infarct volume and neurological deficit scores compared to vehicle-injected MCAo mice. The superior therapeutic efficacy of mBEC-EVs in MCAo mice support the continued use of mBEC-EVs to optimize the therapeutic potential of mitochondria-containing EVs in preclinical mouse models.

Stroke studies in large animals: Prospects of mitochondrial transplantation and enhancing efficiency using hydrogels and nanoparticle-assisted delivery

One of the most frequent reasons for mortality and disability today is acute ischemic stroke, which occurs by an abrupt disruption of cerebral circulation. The intricate damage mechanism involves several factors, such as inflammatory response, disturbance of ion balance, loss of energy production, excessive reactive oxygen species and glutamate release, and finally, neuronal death. Stroke research is now carried out using several experimental models and potential therapeutics. Furthermore, studies are being conducted to address the shortcomings of clinical care. A great deal of research is being done on novel pharmacological drugs, mitochondria targeting compounds, and different approaches including brain cooling and new technologies. Still, there are many unanswered questions about disease modeling and treatment strategies. Before these new approaches may be used in therapeutic settings, they must first be tested on large animals, as most of them have been done on rodents. However, there are several limitations to large animal stroke models used for research. In this review, the damage mechanisms in acute ischemic stroke and experimental acute ischemic stroke models are addressed. The current treatment approaches and promising experimental methods such as mitochondrial transplantation, hydrogel-based interventions, and strategies like mitochondria encapsulation and chemical modification, are also examined in this work.

Intercellular Mitochondrial Transfer: The Novel Therapeutic Mechanism for Diseases

Mitochondria, the dynamic organelles responsible for energy production and cellular metabolism, have the metabolic function of extracting energy from nutrients and synthesizing crucial metabolites. Nevertheless, recent research unveils that intercellular mitochondrial transfer by tunneling nanotubes, tumor microtubes, gap junction intercellular communication, extracellular vesicles, endocytosis and cell fusion may regulate mitochondrial function within recipient cells, potentially contributing to disease treatment, such as nonalcoholic steatohepatitis, glioblastoma, ischemic stroke, bladder cancer and neurodegenerative diseases. This review introduces the principal approaches to intercellular mitochondrial transfer and examines its role in various diseases. Furthermore, we provide a comprehensive overview of the inhibitors and activators of intercellular mitochondrial transfer, offering a unique perspective to illustrate the relationship between intercellular mitochondrial transfer and diseases.

Toxin-derived peptides: An unconventional approach to alleviating cerebral stroke burden and neurobehavioral impairments

Cerebral stroke is a pressing global health concern, ranking as the second leading cause of mortality and resulting in persistent neurobehavioral impairments. Cerebral strokes, triggered by various embolic events, initiate complex signaling pathways involving neuroexcitotoxicity, ionic imbalances, inflammation, oxidative stress, acidosis, and mitochondrial dysfunction, leading to programmed cell death. Currently, the FDA has approved tissue plasminogen activator as a relatively benign intervention for cerebral stroke, leaving a significant treatment gap. However, a promising avenue has emerged from Earth's toxic creatures. Animal venoms harbor bioactive molecules, particularly neuropeptides, with potential in innovative healthcare applications. These venomous components, affecting ion channels, receptors, and transporters, encompass neurochemicals, amino acids, and peptides, making them prime candidates for treating cerebral ischemia and neurological disorders. This review explores the composition, applications, and significance of toxin-derived peptides as viable therapeutic agents. It also investigates diverse toxins from select venomous creatures, with the primary objective of shedding light on current stroke treatments and paving the way for pioneering therapeutic strategies capable of addressing neurobehavioral deficits.

Vagus nerve stimulation in cerebral stroke: biological mechanisms, therapeutic modalities, clinical applications, and future directions

Stroke is a major disorder of the central nervous system that poses a serious threat to human life and quality of life. Many stroke victims are left with long-term neurological dysfunction, which adversely affects the well-being of the individual and the broader socioeconomic impact. Currently, post-stroke brain dysfunction is a major and difficult area of treatment. Vagus nerve stimulation is a Food and Drug Administration-approved exploratory treatment option for autism, refractory depression, epilepsy, and Alzheimer's disease. It is expected to be a novel therapeutic technique for the treatment of stroke owing to its association with multiple mechanisms such as altering neurotransmitters and the plasticity of central neurons. In animal models of acute ischemic stroke, vagus nerve stimulation has been shown to reduce infarct size, reduce post-stroke neurological damage, and improve learning and memory capacity in rats with stroke by reducing the inflammatory response, regulating blood-brain barrier permeability, and promoting angiogenesis and neurogenesis. At present, vagus nerve stimulation includes both invasive and non-invasive vagus nerve stimulation. Clinical studies have found that invasive vagus nerve stimulation combined with rehabilitation therapy is effective in improving upper limb motor and cognitive abilities in stroke patients. Further clinical studies have shown that non-invasive vagus nerve stimulation, including ear/cervical vagus nerve stimulation, can stimulate vagal projections to the central nervous system similarly to invasive vagus nerve stimulation and can have the same effect. In this paper, we first describe the multiple effects of vagus nerve stimulation in stroke, and then discuss in depth its neuroprotective mechanisms in ischemic stroke. We go on to outline the results of the current major clinical applications of invasive and non-invasive vagus nerve stimulation. Finally, we provide a more comprehensive evaluation of the advantages and disadvantages of different types of vagus nerve stimulation in the treatment of cerebral ischemia and provide an outlook on the developmental trends. We believe that vagus nerve stimulation, as an effective treatment for stroke, will be widely used in clinical practice to promote the recovery of stroke patients and reduce the incidence of disability.

Advancing stroke therapy: innovative approaches with stem cell-derived extracellular vesicles

Stroke is a leading cause of mortality and long-term disability globally, with acute ischemic stroke (AIS) being the most common subtype. Despite significant advances in reperfusion therapies, their limited time window and associated risks underscore the necessity for novel treatment strategies. Stem cell-derived extracellular vesicles (EVs) have emerged as a promising therapeutic approach due to their ability to modulate the post-stroke microenvironment and facilitate neuroprotection and neurorestoration. This review synthesizes current research on the therapeutic potential of stem cell-derived EVs in AIS, focusing on their origin, biogenesis, mechanisms of action, and strategies for enhancing their targeting capacity and therapeutic efficacy. Additionally, we explore innovative combination therapies and discuss both the challenges and prospects of EV-based treatments. Our findings reveal that stem cell-derived EVs exhibit diverse therapeutic effects in AIS, such as promoting neuronal survival, diminishing neuroinflammation, protecting the blood-brain barrier, and enhancing angiogenesis and neurogenesis. Various strategies, including targeting modifications and cargo modifications, have been developed to improve the efficacy of EVs. Combining EVs with other treatments, such as reperfusion therapy, stem cell transplantation, nanomedicine, and gut microbiome modulation, holds great promise for improving stroke outcomes. However, challenges such as the heterogeneity of EVs and the need for standardized protocols for EV production and quality control remain to be addressed. Stem cell-derived EVs represent a novel therapeutic avenue for AIS, offering the potential to address the limitations of current treatments. Further research is needed to optimize EV-based therapies and translate their benefits to clinical practice, with an emphasis on ensuring safety, overcoming regulatory hurdles, and enhancing the specificity and efficacy of EV delivery to target tissues.

Advancing stroke recovery: unlocking the potential of cellular dynamics in stroke recovery

Stroke stands as a predominant cause of mortality and morbidity worldwide, and there is a pressing need for effective therapies to improve outcomes and enhance the quality of life for stroke survivors. In this line, effective efferocytosis, the clearance of apoptotic cells, plays a crucial role in neuroprotection and immunoregulation. This process involves specialized phagocytes known as "professional phagocytes" and consists of four steps: "Find-Me," "Eat-Me," engulfment/digestion, and anti-inflammatory responses. Impaired efferocytosis can lead to secondary necrosis and inflammation, resulting in adverse outcomes following brain pathologies. Enhancing efferocytosis presents a potential avenue for improving post-stroke recovery. Several therapeutic targets have been identified, including osteopontin, cysteinyl leukotriene 2 receptor, the µ opioid receptor antagonist β-funaltrexamine, and PPARγ and RXR agonists. Ferroptosis, defined as iron-dependent cell death, is now emerging as a novel target to attenuate post-stroke tissue damage and neuronal loss. Additionally, several biomarkers, most importantly CD163, may serve as potential biomarkers and therapeutic targets for acute ischemic stroke, aiding in stroke diagnosis and prognosis. Non-pharmacological approaches involve physical rehabilitation, hypoxia, and hypothermia. Mitochondrial dysfunction is now recognized as a major contributor to the poor outcomes of brain stroke, and medications targeting mitochondria may exhibit beneficial effects. These strategies aim to polarize efferocytes toward an anti-inflammatory phenotype, limit the ingestion of distressed but viable neurons, and stimulate efferocytosis in the late phase of stroke to enhance post-stroke recovery. These findings highlight promising directions for future research and development of effective stroke recovery therapies.

Mitochondria-containing extracellular vesicles from mouse vs . human brain endothelial cells for ischemic stroke therapy

Ischemic stroke-induced mitochondrial dysfunction in the blood-brain barrier-forming brain endothelial cells ( BECs ) results in long-term neurological dysfunction post-stroke. We previously data from a pilot study where intravenous administration of human BEC ( hBEC )-derived mitochondria-containing extracellular vesicles ( EVs ) showed a potential efficacy signal in a mouse middle cerebral artery occlusion ( MCAo ) model of stroke. We hypothesized that EVs harvested from donor species homologous to the recipient species ( e.g., mouse) may improve therapeutic efficacy, and therefore, use of mouse BEC ( mBEC )-derived EVs may improve post-stroke outcomes in MCAo mice. We investigated potential differences in the mitochondria transfer of EVs derived from the same species as the recipient cell (mBEC-EVs and recipient mBECs or hBECs-EVs and recipient hBECs) vs . cross-species EVs and recipient cells (mBEC-EVs and recipient hBECs or vice versa ). Our results showed that while both hBEC- and mBEC-EVs transferred EV mitochondria, mBEC-EVs outperformed hBEC-EVs in increasing ATP levels and improved recipient mBEC mitochondrial function via increasing oxygen consumption rates. mBEC-EVs significantly reduced brain infarct volume and neurological deficit scores compared to vehicle-injected MCAo mice. The superior therapeutic efficacy of mBEC-EVs in a mouse MCAo stroke support the continued use of mBEC-EVs to optimize the therapeutic potential of mitochondria-containing EVs in preclinical mouse models.

The neuroprotective effects of normobaric oxygen therapy after stroke

BACKGROUND

Stroke, including ischemic and hemorrhagic stroke, is a severe and prevalent acute cerebrovascular disease. The development of hypoxia following stroke can trigger a cascade of pathological events, including mitochondrial dysfunction, energy deficiency, oxidative stress, neuroinflammation, and excitotoxicity, all of which are often associated with unfavorable prognosis. Nonetheless, a noninvasive intervention, referred to as normobaric hyperoxia (NBO), is known to have neuroprotective effects against stroke.

RESULTS

NBO can exert neuroprotective effects through various mechanisms, such as the rescue of hypoxic tissues, preservation of the blood-brain barrier, reduction of brain edema, alleviation of neuroinflammation, improvement of mitochondrial function, mitigation of oxidative stress, reduction of excitotoxicity, and inhibition of apoptosis. These mechanisms may help improve the prognosis of stroke patients.

CONCLUSIONS

This review summarizes the mechanism by which hypoxia causes brain injury and how NBO can act as a neuroprotective therapy to treat stroke. We conclude that NBO has significant potential for treating stroke and may represent a novel therapeutic strategy.

SIRT3 facilitates mitochondrial structural repair and functional recovery in rats after ischemic stroke by promoting OPA1 expression and activity

BACKGROUND

Optical atrophy 1 (OPA1), a protein accountable for mitochondrial fusion, facilitates the restoration of mitochondrial structure and function following cerebral ischemia/reperfusion (I/R) injury. The OPA1-conferred mitochondrial protection involves its expression and activity, which can be improved by SIRT3 in non-cerebral ischemia. Nevertheless, it remains obscure whether SIRT3 enhances the expression and activity of OPA1 after cerebral I/R injury.

METHODS

Mature male Sprague Dawley rats were intracranially injected with adeno-associated viral-Sirtuin-3(AAV-SIRT3) and AAV-sh_OPA1, followed by a 90-min temporary blockage of the middle cerebral artery and subsequent restoration of blood flow. Cultured cortical neurons of rats were transfected with LV-SIRT3 or LV-sh_OPA1 before a 2-h oxygen-glucose deprivation and reoxygenation. The rats and neurons were subsequently treated with a selective OPA1 activity inhibitor (MYLS22). The interaction between SIRT3 and OPA1 was assessed by molecular dynamics simulation technology and co-immunoprecipitation. The expression, function, and specific protective mechanism of SIRT3 were examined by various analyses.

RESULTS

SIRT3 interacted with OPA1 in the rat cerebral cortex before and after cerebral I/R. After cerebral I/R damage, SIRT3 upregulation increased the OPA1 expression, which enhanced deacetylation and OPA1 activity, thus alleviating cerebral infarct volume, neuronal apoptosis, oxidative pressure, and impairment in mitochondrial energy production; SIRT3 upregulation also improved neuromotor performance, repaired mitochondrial ultrastructure and membrane composition, and promoted the mitochondrial biogenesis. These neuroprotective effects were partly reversed by OPA1 expression interference and OPA1 activity inhibitor MYLS22.

CONCLUSION

In rats, SIRT3 enhances the expression and activity of OPA1, facilitating the repair of mitochondrial structure and functional recovery following cerebral I/R injury. These findings highlight that regulating SIRT3 may be a promising therapeutic strategy for ischemic stroke.

The underlying mechanism of calcium toxicity-induced autophagic cell death and lysosomal degradation in early stage of cerebral ischemia

Cerebral ischemia is the important cause of worldwide disability and mortality, that is one of the obstruction of blood vessels supplying to the brain. In early stage, glutamate excitotoxicity and high level of intracellular calcium (Ca2+) are the major processes which can promote many downstream signaling involving in neuronal death and brain tissue damaging. Moreover, autophagy, the reusing of damaged cell organelles, is affected in early ischemia. Under ischemic conditions, autophagy plays an important role to maintain energy of the brain and its function. In the other hand, over intracellular Ca2+ accumulation triggers excessive autophagic process and lysosomal degradation leading to autophagic process impairment which finally induce neuronal death. This article reviews the association between intracellular Ca2+ and autophagic process in acute stage of ischemic stroke.

Menaquinone-4 alleviates hypoxic-ischemic brain damage in neonatal rats by reducing mitochondrial dysfunction via Sirt1-PGC-1α-TFAM signaling pathway

BACKGROUND

Hypoxic-ischemic encephalopathy (HIE) is a major contributor to neonatal mortality and neurodevelopmental disorders, but currently there is no effective therapy drug for HIE. Mitochondrial dysfunction plays a pivotal role in hypoxic-ischemic brain damage(HIBD). Menaquinone-4 (MK-4), a subtype of vitamin K2 prevalent in the brain, has been shown to enhance mitochondrial function and exhibit protective effects against ischemia-reperfusion injury. However, the impact and underlying molecular mechanism of MK-4 in HIE have not been fully elucidated.

METHODS

In this study, we established the neonatal rats HIBD model in vivo and oxygen-glucose deprivation and reperfusion (OGD/R) of primary neurons in vitro to explore the neuroprotective effects of MK-4 on HI damage, and illuminate the potential mechanism.

RESULTS

Our findings revealed that MK-4 ameliorated mitochondrial dysfunction, reduced oxidative stress, and prevented HI-induced neuronal apoptosis by activating the Sirt1-PGC-1α-TFAM signaling pathway through Sirt1 mediation. Importantly, these protective effects were partially reversed by EX-527, a Sirt1 inhibitor.

CONCLUSION

Our study elucidated the potential therapeutic mechanism of MK-4 in neonatal HIE, suggesting its viability as an agent for enhancing recovery from HI-induced cerebral damage in newborns. Further exploration into MK-4 could lead to novel interventions for HIE therapy.

Molecular Pathogenesis of Ischemic and Hemorrhagic Strokes: Background and Therapeutic Approaches

Stroke represents one of the neurological diseases most responsible for death and permanent disability in the world. Different factors, such as thrombus, emboli and atherosclerosis, take part in the intricate pathophysiology of stroke. Comprehending the molecular processes involved in this mechanism is crucial to developing new, specific and efficient treatments. Some common mechanisms are excitotoxicity and calcium overload, oxidative stress and neuroinflammation. Furthermore, non-coding RNAs (ncRNAs) are critical in pathophysiology and recovery after cerebral ischemia. ncRNAs, particularly microRNAs, and long non-coding RNAs (lncRNAs) are essential for angiogenesis and neuroprotection, and they have been suggested to be therapeutic, diagnostic and prognostic tools in cerebrovascular diseases, including stroke. This review summarizes the intricate molecular mechanisms underlying ischemic and hemorrhagic stroke and delves into the function of miRNAs in the development of brain damage. Furthermore, we will analyze new perspectives on treatment based on molecular mechanisms in addition to traditional stroke therapies.

4'-O-methylbavachalcone alleviates ischemic stroke injury by inhibiting parthanatos and promoting SIRT3

Cerebral ischemia-reperfusion injury (CIRI) can induce massive death of ischemic penumbra neurons via oxygen burst, exacerbating brain damage. Parthanatos is a form of caspase-independent cell death involving excessive activation of PARP-1, closely associated with intense oxidative stress following CIRI. 4'-O-methylbavachalcone (MeBavaC), an isoprenylated chalcone component in Fructus Psoraleae, has potential neuroprotective effects. This study primarily investigates whether MeBavaC can act on SIRT3 to alleviate parthanatos of ischemic penumbra neurons induced by CIRI. MeBavaC was oral gavaged to the middle cerebral artery occlusion-reperfusion (MCAO/R) rats after occlusion. The effects of MeBavaC on cerebral injury were detected by the neurological deficit score and cerebral infarct volume. In vitro, PC-12 cells were subjected to oxygen and glucose deprivation/reoxygenation (OGD/R), and assessed cell viability and cell injury. Also, the levels of ROS, mitochondrial membrane potential (MMP), and intracellular Ca2+ levels were detected to reflect mitochondrial function. We conducted western blotting analyses of proteins involved in parthanatos and related signaling pathways. Finally, the exact mechanism between the neuroprotection of MeBavaC and parthanatos was explored. Our results indicate that MeBavaC reduces the cerebral infarct volume and neurological deficit scores in MCAO/R rats, and inhibits the decreased viability of PC-12 cells induced by OGD/R. MeBavaC also downregulates the expression of parthanatos-related death proteins PARP-1, PAR, and AIF. However, this inhibitory effect is weakened after the use of a SIRT3 inhibitor. In conclusion, the protective effect of MeBavaC against CIRI may be achieved by inhibiting parthanatos of ischemic penumbra neurons through the SIRT3-PARP-1 axis.

Chronic Sustained Hypoxia Leads to Brainstem Tauopathy and Declines the Power of Rhythms in the Ventrolateral Medulla: Shedding Light on a Possible Mechanism

Hypoxia, especially the chronic type, leads to disruptive results in the brain that may contribute to the pathogenesis of some neurodegenerative diseases such as Alzheimer's disease (AD). The ventrolateral medulla (VLM) contains clusters of interneurons, such as the pre-Bötzinger complex (preBötC), that generate the main respiratory rhythm drive. We hypothesized that exposing animals to chronic sustained hypoxia (CSH) might develop tauopathy in the brainstem, consequently changing the rhythmic manifestations of respiratory neurons. In this study, old (20-22 months) and young (2-3 months) male rats were subjected to CSH (10 ± 0.5% O2) for ten consecutive days. Western blotting and immunofluorescence (IF) staining were used to evaluate phosphorylated tau. Mitochondrial membrane potential (MMP or ∆ψm) and reactive oxygen species (ROS) production were measured to assess mitochondrial function. In vivo diaphragm's electromyography (dEMG) and local field potential (LFP) recordings from preBötC were employed to assess the respiratory factors and rhythmic representation of preBötC, respectively. Findings showed that ROS production increased significantly in hypoxic groups, associated with a significant decline in ∆ψm. In addition, tau phosphorylation elevated in the brainstem of hypoxic groups. On the other hand, the power of rhythms declined significantly in the preBötC of hypoxic rats, parallel with changes in the respiratory rate, total respiration time, and expiration time. Moreover, there was a positive and statistically significant correlation between LFP rhythm's power and inspiration time. Our data showed that besides CSH, aging also contributed to mitochondrial dysfunction, tau hyperphosphorylation, LFP rhythms' power decline, and changes in respiratory factors.

Electroacupuncture reduces oxidative stress response and improves secondary injury of intracerebral hemorrhage in rats by activating the peroxisome proliferator-activated receptor-γ/nuclear factor erythroid2-related factor 2/γ-glutamylcysteine synthetase pathway

Intracerebral hemorrhage (ICH) is a severe stroke subtype. Secondary injury is a key factor leading to neurological deficits after ICH. Electroacupuncture (EA) can improve the neurological function after ICH, however, its internal mechanism is still unclear. The aim of this study is to investigate whether EA could ameliorate secondary injury after ICH through antioxidative stress and its potential regulatory mechanism. A rat model of ICH was established by injecting autologous blood into striatum. After the intervention of EA and EA combined with peroxisome proliferator-activated receptor-γ (PPARγ) blocker, Zea-longa scores, modified neurological severity scores and open field tests were used to evaluate the neurological function of the rats. Flow cytometry detected tissue reactive oxygen species (ROS) levels. Tissue tumor necrosis factor-α (TNF-α) levels were analyzed by enzyme-linked immunosorbent assays. The protein expressions of PPAR γ, nuclear factor erythroid2-related factor 2 (Nrf2) and γ-glutamylcysteine synthetase (γ-GCS) were detected by Western blot. Immunohistochemistry was used to observe the activation of microglia. The demyelination degree of axon myelin was observed by transmission electron microscope. Compared with the model group, EA intervention improved neurological function, decreased ROS and TNF-α levels, increased the protein expression of PPARγ, Nrf2 and γ-GCS, and reduced the activation of microglia, it also alleviated axonal myelin sheath damage. In addition, the neuroprotective effect of EA was partially attenuated by PPARγ blocker. EA ameliorated the neurological function of secondary injury after ICH in rats, possibly by activating the PPARγ/Nrf2/γ-GCS signaling pathway, reducing microglia activation, and inhibiting oxidative stress, thus alleviating the extent of axonal demyelination plays a role.

Promising use of metformin in treating neurological disorders: biomarker-guided therapies

Neurological disorders are a diverse group of conditions that affect the nervous system and include neurodegenerative diseases (Alzheimer's disease, multiple sclerosis, Parkinson's disease, Huntington's disease), cerebrovascular conditions (stroke), and neurodevelopmental disorders (autism spectrum disorder). Although they affect millions of individuals around the world, only a limited number of effective treatment options are available today. Since most neurological disorders express mitochondria-related metabolic perturbations, metformin, a biguanide type II antidiabetic drug, has attracted a lot of attention to be repurposed to treat neurological disorders by correcting their perturbed energy metabolism. However, controversial research emerges regarding the beneficial/detrimental effects of metformin on these neurological disorders. Given that most neurological disorders have complex etiology in their pathophysiology and are influenced by various risk factors such as aging, lifestyle, genetics, and environment, it is important to identify perturbed molecular functions that can be targeted by metformin in these neurological disorders. These molecules can then be used as biomarkers to stratify subpopulations of patients who show distinct molecular/pathological properties and can respond to metformin treatment, ultimately developing targeted therapy. In this review, we will discuss mitochondria-related metabolic perturbations and impaired molecular pathways in these neurological disorders and how these can be used as biomarkers to guide metformin-responsive treatment for the targeted therapy to treat neurological disorders.

Unraveling brain diseases: The promise of brain-on-a-chip models

Brain disorders, encompassing a wide spectrum of neurological and psychiatric conditions, present a formidable challenge in modern medicine. Despite decades of research, the intricate complexity of the human brain still eludes comprehensive understanding, impeding the development of effective treatments. Recent advancements in microfluidics and tissue engineering have led to the development of innovative platforms known as "Brain-on-a-Chip" (BoC) i.e., advanced in vitro systems that aim to replicate the microenvironment of the brain with the highest possible fidelity. This technology offers a promising test-bed for studying brain disorders at the cellular and network levels, providing insights into disease mechanisms, drug screening, and, in perspective, the development of personalized therapeutic strategies. In this review, we provide an overview of the BoC models developed over the years to model and understand the onset and progression of some of the most severe neurological disorders in terms of incidence and debilitation (stroke, Parkinson's, Alzheimer's, and epilepsy). We also report some of the cutting-edge therapeutic approaches whose effects were evaluated by means of these technologies. Finally, we discuss potential challenges, and future perspectives of the BoC models.

Unlocking the Mitochondria for Nanomedicine-based Treatments: Overcoming Biological Barriers, Improving Designs, and Selecting Verification Techniques

Enhanced targeting approaches will support the treatment of diseases associated with dysfunctional mitochondria, which play critical roles in energy generation and cell survival. Obstacles to mitochondria-specific targeting include the presence of distinct biological barriers and the need to pass through (or avoid) various cell internalization mechanisms. A range of studies have reported the design of mitochondrially-targeted nanomedicines that navigate the complex routes required to influence mitochondrial function; nonetheless, a significant journey lies ahead before mitochondrially-targeted nanomedicines become suitable for clinical use. Moving swiftly forward will require safety studies, in vivo assays confirming effectiveness, and methodologies to validate mitochondria-targeted nanomedicines' subcellular location/activity. From a nanomedicine standpoint, we describe the biological routes involved (from administration to arrival within the mitochondria), the features influencing rational design, and the techniques used to identify/validate successful targeting. Overall, rationally-designed mitochondria-targeted-based nanomedicines hold great promise for precise subcellular therapeutic delivery.

Astragaloside IV combined with ligustrazine ameliorates abnormal mitochondrial dynamics via Drp1 SUMO/deSUMOylation in cerebral ischemia-reperfusion injury

OBJECTIVES

Astragaloside IV (AST IV) and ligustrazine (Lig), the main ingredients of Astragali Radix and Chuanxiong Rhizoma respectively, have demonstrated significant benefits in treatment of cerebral ischemia -reperfusion injury (CIRI); however, the mechanisms underlying its benificial effects remain unclear. SUMO-1ylation and deSUMO-2/3ylation of dynamin-related protein 1 (Drp1) results in mitochondrial homeostasis imbalance following CIRI, which subsequently aggravates cell damage. This study investigates the mechanisms by which AST IV combined with Lig protects against CIRI, focusing on the involvement of SUMOylation in mitochondrial dynamics.

METHODS

Rats were administrated AST IV and Lig for 7 days, and middle cerebral artery occlusion was established to mimic CIRI. Neural function, cerebral infarction volume, cerebral blood flow, cognitive function, cortical pathological lesions, and mitochondrial morphology were measured. SH-SY5Y cells were subjected to oxygen-glucose deprivation/reoxygenation (OGD/R) injury. Mitochondrial membrane potential and lactic dehydrogenase (LDH), reactive oxygen species (ROS), and adenosine triphosphate (ATP) levels were assessed with commercial kits. Moreover, co-immunoprecipitation (Co-IP) was used to detect the binding of SUMO1 and SUMO2/3 to Drp1. The protein expressions of Drp1, Fis1, MFF, OPA1, Mfn1, Mfn2, SUMO1, SUMO2/3, SENP1, SENP2, SENP3, SENP5, and SENP6 were measured using western blot.

RESULTS

In rats with CIRI, AST IV and Lig improved neurological and cognitive functions, restored CBF, reduced brain infarct volume, and alleviated cortical neuron and mitochondrial damage. Moreover, in SH-SY5Y cells, the combination of AST IV and Lig enhanced cellular viability, decreased release of LDH and ROS, increased ATP content, and improved mitochondrial membrane potential. Furthermore, AST IV combined with Lig reduced the binding of Drp1 with SUMO1, increased the binding of Drp1 with SUMO2/3, suppressed the expressions of Drp1, Fis1, MFF, and SENP3, and increased the expressions of OPA1, Mfn1, Mfn2, SENP1, SENP2, and SENP5. SUMO1 overexpression promoted mitochondrial fission and inhibited mitochondrial fusion, whereas SUMO2/3 overexpression suppressed mitochondrial fission. AST IV combined with Lig could reverse the effects of SUMO1 overexpression while enhancing those of SUMO2/3 overexpression.

CONCLUSIONS

This study posits that the combination of AST IV and Lig has the potential to reduce the SUMO-1ylation of Drp1, augment the SUMO-2/3ylation of Drp1, and thereby exert a protective effect against CIRI.

The role of mitochondrial transfer via tunneling nanotubes in the central nervous system: A review

Tumour necrosis factor alpha-induced protein 2 (TNFAIP2) is a gene induced by tumor necrosis factor in endothelial cells. TNFAIP2 has important functions in physiological and pathological processes, including cell proliferation, adhesion, migration, angiogenesis, inflammation, tunneling nanotube (TNT) formation and tumorigenesis. Moreover, TNFAIP2 is the key factor in the formation of TNTs. TNTs are related to signal transduction between different cell types and are considered a novel means of cell-to-cell communication. Mesenchymal stem cells (MSCs) are pluripotent cells that exhibit self-renewal, multidirectional differentiation, paracrine function and immune-regulating ability. MSCs can transfer mitochondria through TNTs to improve the functions of target cells. This review revealed that TNFAIP2 promotes the formation of TNTs and that MSCs rely on TNTs for mitochondrial transfer to ameliorate cell dysfunction.

Astrocytes in intracerebral hemorrhage: impact and therapeutic objectives

Intracerebral hemorrhage (ICH) manifests precipitously and profoundly impairs the neurological function in patients who are affected. The etiology of subsequent injury post-ICH is multifaceted, characterized by the intricate interplay of various factors, rendering therapeutic interventions challenging. Astrocytes, a distinct class of glial cells, interact with neurons and microglia, and are implicated in a series of pathophysiological alterations following ICH. A comprehensive examination of the functions and mechanisms associated with astrocytic proteins may shed light on the role of astrocytes in ICH pathology and proffer innovative therapeutic avenues for ICH management.

NMR based Serum metabolomics revealed metabolic signatures associated with oxidative stress and mitochondrial damage in brain stroke

Brain stroke (BS, also known as a cerebrovascular accident), represents a serious global health crisis. It has been a leading cause of permanent disability and unfortunately, frequent fatalities due to lack of timely medical intervention. While progress has been made in prevention and management, the complexities and consequences of stroke continue to pose significant challenges, especially, its impact on patient's quality of life and independence. During stroke, there is a substantial decrease in oxygen supply to the brain leading to alteration of cellular metabolic pathways, including those involved in mitochondrial-damage, leading to mitochondrial-dysfunction. The present proof-of-the-concept metabolomics study has been performed to gain insights into the metabolic pathways altered following a brain stroke and discover new potential targets for timely interventions to mitigate the effects of cellular and mitochondrial damage in BS. The serum metabolic profiles of 108 BS-patients were measured using 800 MHz NMR spectroscopy and compared with 60 age and sex matched normal control (NC) subjects. Compared to NC, the serum levels of glutamate, TCA-cycle intermediates (such as citrate, succinate, etc.), and membrane metabolites (betaine, choline, etc.) were found to be decreased BS patients, whereas those of methionine, mannose, mannitol, phenylalanine, urea, creatine and organic acids (such as 3-hydroxybutyrate and acetone) were found to be elevated in BS patients. These metabolic changes hinted towards hypoxia mediated mitochondrial dysfunction in BS-patients. Further, the area under receiver operating characteristic curve (ROC) values for five metabolic features (methionine, mannitol, phenylalanine, mannose and urea) found to be more than 0.9 suggesting their high sensitivity and specificity for differentiating BS from NC subjects.