Animal Models Of Ischemic Stroke Research Articles

Effect and mechanisms of resveratrol in animal models of ischemic stroke: A systematic review and Bayesian meta-analysis

Resveratrol (RSV) holds promise as cerebroprotective treatment in cerebral ischemia. This systematic review aims to assess the effects and mechanisms of RSV in animal models of ischemic stroke. We searched Medline, Embase and Web of Science to identify 75 and 57 eligible rodent studies for qualitative and quantitative syntheses, respectively. Range of evidence met 10 of 13 STAIR criteria. Median (Q1, Q3) quality score was 7 (5, 8) on the CAMARADES 15-item checklist. Bayesian meta-analysis showed SMD estimates (95% CI) favoring RSV: infarct size (−1.72 [−2.03; −1.41]), edema size (−1.61 [−2.24; −0.98]), BBB impairment (−1.85 [−2.54; −1.19]), neurofunctional impairment (−1.60 [−1.92; −1.29]), and motor performance (1.39 [0.64; 2.08]); and less probably neuronal survival (0.63 [−1.40; 2.48]) and apoptosis (−0.96 [−2.87; 1.02]). Species (rat vs mouse) was associated to a larger benefit. Sensitivity analyses confirmed robustness of the estimates. Reduction of oxidative stress, inflammation, and apoptosis underlie these effects. Our results quantitatively state the beneficial effects of RSV on structural and functional outcomes in rodent stroke models, update the evidence on the mechanisms of action, and provide an exhaustive list of targeted signaling pathways. Current evidence highlights the need for conducting further high-quality preclinical research to better inform clinical research.

Animal Models of Ischemic Stroke with Different Forms of Middle Cerebral Artery Occlusion.

Ischemic stroke is a common type of stroke that significantly affects human well-being and quality of life. In order to further characterize the pathophysiology of ischemic stroke and develop new treatment strategies, ischemic stroke models with controllable and consistent response to potential clinical treatments are urgently needed. The middle cerebral artery occlusion (MCAO) model is currently the most widely used animal model of ischemic stroke. This review discusses various methods for constructing the MCAO model and compares their advantages and disadvantages in order to provide better approaches for studying ischemic stroke.

HABP2 Encapsulated by Peripheral Blood-Derived Exosomes Suppresses Astrocyte Autophagy to Exacerbate Neuroinflammatory Injury in Mice with Ischemic Stroke.

Exosomes are shown to be involved in the regulation of neuroinflammatory injury. The current study analyzed how peripheral blood-derived exosomes affected hyaluronan-binding protein 2 (HABP2) expression to regulate neuroinflammatory injury after ischemic stroke (IS). An IS animal model was stimulated by middle cerebral artery occlusion (MCAO), followed by injection of lentivirus. Peripheral blood samples were collected from MCAO mice after different treatments. The cerebral infarction volume, astrocyte activation, and neuroinflammation were observed by TTC staining, immunofluorescence, and ELISA, respectively. HABP2 was highly expressed in the brain tissues of MCAO mice. Also, an enhancement of HABP2 was noted in their peripheral blood-derived exosomes, while loss of HABP2 in peripheral blood-derived exosomes promoted the astrocyte autophagy and reduced the release of the inflammatory factors as well as the apoptosis of neuronal cells. PAR1 overexpression reversed the effect of HABP2 loss on autophagy and neuroinflammation in MCAO mice. Additionally, the agonist of the PI3K/AKT/mTOR pathway, SC79, could also reverse the effect of sh-PAR1 on neuroinflammation. Mechanistically, HABP2 enhanced PAR1 to activate the PI3K/AKT/mTOR pathway, thereby suppressing cell autophagy. Overall, HABP2 in peripheral blood-derived exosomes can activate the PAR1/PI3K/AKT/mTOR pathway to reduce autophagy and aggravate neuroinflammatory injury after IS.

Perlecan: a review of its role in neurologic and musculoskeletal disease.

Perlecan is a 500kDa proteoglycan residing in the extracellular matrix of endothelial basement membranes with five distinct protein domains and three heparan sulfate chains. The complex structure of perlecan and the interaction it has with its local environment accounts for its various cellular and tissue-related effects, to include cartilage, bone, neural and cardiac development, angiogenesis, and blood brain barrier stability. As perlecan is a key contributor to extracellular matrix health involved in many tissues and processes throughout the body, dysregulation of perlecan has the potential to contribute to various neurological and musculoskeletal diseases. Here we review key findings associated with perlecan dysregulation in the context of disease. This is a narrative review article examining perlecan’s role in diseases of neural and musucloskeletal pathology and its potential as a therapeutic index. Literature searches were conducted on the PubMed database, and were focused on perlecan's impact in neurological disease, to include ischemic stroke, Alzheimer's Disease (AD) and brain arteriovenous malformation (BAVM), as well as musculoskeletal pathology, including Dyssegmental Dysplasia Silverman-Handmaker type (DDSH), Schwartz-Jampel syndrome (SJS), sarcopenia, and osteoarthritis (OA). PRISMA guidelines were utilized in the search and final selection of articles.Increased perlecan levels were associated with sarcopenia, OA, and BAVM, while decreased perlecan was associated with DDSH, and SJS. We also examined the therapeutic potential of perlecan signaling in ischemic stroke, AD, and osteoarthritic animal models. Perlecan experimentally improved outcomes in such models of ischemic stroke and AD, and we found that it may be a promising component of future therapeutics for such pathology. In treating the pathophysiology of sarcopenia, OA, and BAVM, inhibiting the effect of perlecan may be beneficial. As perlecan binds to both α-5 integrin and VEGFR2 receptors, tissue specific inhibitors of these proteins warrant further study. In addition, analysis of experimental data revealed promising insight into the potential uses of perlecan domain V as a broad treatment for ischemic stroke and AD. As these diseases have limited therapeutic options, further study into perlecan or its derivatives and its potential to be used as novel therapeutic for these and other diseases should be seriously considered.

Effect of Thiamine on Serum Glutamate in Ischemic Stroke Animal Model

Effect of Thiamine on Serum Glutamate in Ischemic Stroke Animal Model

Pathophysiology of Stroke: A Molecular Mechanism Perspective

Stroke is a major cause of death and disability worldwide. The Resulting burden on the society continues to grow, with increase in the incidence of Stroke. Brain attack is a term introduced to describe the acute presentation of stroke, which emphasizes the need for urgent action to remedy the situation. While these observations underpinned key trials of thrombolysis, they also indicate that only patients who are likely to benefit should be exposed to its risks. This review explores the etiology and pathogenesis of ischemic stroke, and provides general information of model. This literature review examines the risk factors associated with ischemic stroke, changes in cell morphology and signaling in the brain after stroke. The Pathophysiology of cerebral ischemic injury is explained, and experimental animal models of global and focal ischemic stroke, and in vitro cellular stroke models, are described in details along with mechanism. This article is dedicated to acute ischemic strokes and its molecular mechanism. Classification systems for stroke a etiology are also discussed briefly, as well as current ischemic stroke therapies and new therapeutic strategies and clinical studies that focus on the potential of stroke recovery.

Lycium barbarum Ameliorates Neural Damage Induced by Experimental Ischemic Stroke and Radiation Exposure.

Ischemic stroke and cranial radiotherapy may induce brain inflammatory response, oxidative stress, apoptosis and neuronal loss, and impairment of neurogenesis. Lycium barbarum has anti-oxidation, anti-inflammatory, anti-tumor and anti-aging properties, may produce both neuroprotective and radioprotective effects. In this narrative review paper, we described the neuroprotective effect of Lycium barbarum in different animal models of experimental ischemic stroke and limited studies in irradiated animal models. Relevant molecular mechanisms are also summarized. It has been shown that in experimental ischemic stroke models, Lycium barbarum produces neuroprotective effects by modulating neuroinflammatory factors such as cytokines and chemokines, reactive oxygen species, and neurotransmitter and receptor systems. In irradiation animal models, Lycium barbarum prevents radiation-induced loss of hippocampal interneurons. Given its minimal side-effects, these preclinical studies suggest that Lycium barbarum may be a promising radio-neuro-protective drug that can be used as an adjunct treatment to radiotherapy for brain tumor and in the treatment of ischemic stroke. At molecular levels, Lycium barbarum may regulate PI3K/Akt/GSK-3β, PI3K/Akt/mTOR, PKCε/Nrf2/HO-1, keap1-Nrf2/HO-1, and NR2A and NR2B receptor- related signal transduction pathways to produce neuroprotective effects.

Anti-Inflammatory Effects of Flavonoids in Common Neurological Disorders Associated with Aging

Aging reduces homeostasis and contributes to increasing the risk of brain diseases and death. Some of the principal characteristics are chronic and low-grade inflammation, a general increase in the secretion of proinflammatory cytokines, and inflammatory markers. Aging-related diseases include focal ischemic stroke and neurodegenerative diseases such as Alzheimer's disease (AD) and Parkinson's disease (PD). Flavonoids are the most common class of polyphenols and are abundantly found in plant-based foods and beverages. A small group of individual flavonoid molecules (e.g., quercetin, epigallocatechin-3-gallate, and myricetin) has been used to explore the anti-inflammatory effect in vitro studies and in animal models of focal ischemic stroke and AD and PD, and the results show that these molecules reduce the activated neuroglia and several proinflammatory cytokines, and also, inactivate inflammation and inflammasome-related transcription factors. However, the evidence from human studies has been limited. In this review article, we highlight the evidence that individual natural molecules can modulate neuroinflammation in diverse studies from in vitro to animal models to clinical studies of focal ischemic stroke and AD and PD, and we discuss future areas of research that can help researchers to develop new therapeutic agents.

Ameliorative effects of 6‑gingerol in cerebral ischemia are mediated via the activation of antioxidant and anti‑inflammatory pathways.

Focal ischemia occurs when an embolus or thrombus occludes an artery, causing the rapid obstruction of cerebral blood flow. Although stroke represents a main cause of disability and mortality in developing countries, therapeutic approaches available for this condition remain very limited. The aim of the present study was to examine the effects of the phytochemical, 6-gingerol, on the brain infarct volume, neuronal loss and on the oxidative stress parameters, cyclooxygenase-2 (COX-2) and interleukin (IL)-6, in an animal model of focal ischemic stroke. Male Wistar rats, weighing 250-300 g, were divided into the following six groups: i) The control; ii) right middle cerebral artery occlusion (Rt.MCAO) + vehicle; iii) Rt.MCAO + piracetam; iv) Rt.MCAO + 6-gingerol (6-Gin) at 5 mg/kg body weight (BW); v) Rt.MCAO + 6-Gin at 10 mg/kg BW; and vi) the Rt.MCAO + 6-Gin at 20 mg/kg BW group. The rats in each group received the vehicle or piracetam or 6-gingerol intraperitoneally for 7 days following Rt.MCAO. The brain infarct volume, neuronal loss and alterations in antioxidant and anti-inflammatory levels were assessed in the cortex and hippocampus. The results revealed that the brain infarct volume, malondialdehyde level and the density ratio of COX-2 and IL-6 to β-actin were significantly decreased following treatment with 6-gingerol. In addition, neuronal density and superoxide dismutase activity in the cortex and hippocampus were increased. On the whole, the findings of the present study suggest that 6-gingerol exerts antioxidant and anti-inflammatory effects in vivo, which effectively ameliorate the brain damage induced by focal cerebral ischemic strok.

A Pilot Systematic Review and Meta-analysis of Neuroprotective Studies in Female Rodent Models of Ischemic Stroke.

Most ischemic stroke (IS) patients go untreated due to limited treatment windows, restrictive eligibility criteria, and poor availability of current clinical therapies. Neuroprotective treatments targeting protracted neurodegeneration are needed yet keep failing in clinical trials. Over half of IS patients are female, and the scarcity of neuroprotective studies using female animals hinders translational success. This pilot review and meta-analysis assessed the relationship between the risk of bias and efficacy of studies testing post-ischemic neuroprotective therapies using female rodent models of IS. We carried out a systematic search of the PubMed database for studies published between 1999 and May 2022, used the CAMARADES checklist to evaluate study quality, and extracted data pertaining to lesion volume and behavioral assessment. We found that 34 studies met our inclusion criteria, with pooled effect sizes depicting a significant treatment effect. However, researchers used mostly healthy young females, administered therapies within short time windows, ignored hormonal influences, and did not assess long-term outcomes. Interestingly, studies failing to report factors impacting internal validity, such as blinding and random allocation, had inflated effect sizes or did not reach statistical significance. There was also a relationship between low study quality and larger effect sizes for functional outcome, stressing the need to follow the existing translational design, reporting, and data analysis guidelines. In this review, we cover previous recommendations and offer our own in hopes that rigorous and meticulous research using female animal models of IS will increase our chances of successful bench-to-bedside translation.

Cardiolipin-Mediated Alleviation of Mitochondrial Dysfunction Is a Neuroprotective Effect of Statin in Animal Model of Ischemic Stroke.

In clinical settings, the benefit of statin for stroke is debatable as regular statin users may suffer from myalgia, statin-associated myopathy (SAM), and rarely rhabdomyolysis. Studies suggest that patients on statin therapy show lesser vulnerability toward ischemic stroke and post-stroke frailty. Both pre- and post-treatment benefits of statin have been reported as evident by its neuroprotective effects in both cases. As mitochondrial dysfunction following stroke is the fulcrum for neuronal death, we hereby explore the role of statin in alleviating mitochondrial dysfunction by regulating the mitochondrial dynamics. In the present study, we intend to evaluate the role of statin in modulating cardiolipin-mediated mitochondrial functionality and further providing a therapeutic rationale for repurposing statins either as preventive or an adjunctive therapy for stroke.

α7 nicotinic acetylcholine receptor agonist improved brain injury and impaired glucose metabolism in a rat model of ischemic stroke.

Vagus nerve stimulation through the action of acetylcholine can modulate inflammatory responses and metabolism. α7 Nicotinic Acetylcholine Receptor (α7nAChR) is a key component in the biological functions of acetylcholine. To further explore the health benefits of vagus nerve stimulation, this study aimed to investigate whether α7nAChR agonists offer beneficial effects against poststroke inflammatory and metabolic changes and to identify the underlying mechanisms in a rat model of stroke established by permanent cerebral ischemia. We found evidence showing that pretreatment with α7nAChR agonist, GTS-21, improved poststroke brain infarction size, impaired motor coordination, brain apoptotic caspase 3 activation, dysregulated glucose metabolism, and glutathione reduction. In ischemic cortical tissues and gastrocnemius muscles with GTS-21 pretreatment, macrophages/microglia M1 polarization-associated Tumor Necrosis Factor-α (TNF-α) mRNA, Cluster of Differentiation 68 (CD68) protein, and Inducible Nitric Oxide Synthase (iNOS) protein expression were reduced, while expression of anti-inflammatory cytokine IL-4 mRNA, and levels of M2 polarization-associated CD163 mRNA and protein were increased. In the gastrocnemius muscles, stroke rats showed a reduction in both glutathione content and Akt Serine 473 phosphorylation, as well as an elevation in Insulin Receptor Substrate-1 Serine 307 phosphorylation and Dynamin-Related Protein 1 Serine 616 phosphorylation. GTS-21 reversed poststroke changes in the gastrocnemius muscles. Overall, our findings, provide further evidence supporting the neuroprotective benefits of α7nAChR agonists, and indicate that they may potentially exert anti-inflammatory and metabolic effects peripherally in the skeletal muscle in an acute ischemic stroke animal model.

Tat-NTS peptide protects neurons against cerebral ischemia-reperfusion injury via ANXA1 SUMOylation in microglia.

Rationale: Recent studies indicate that microglial activation and the resulting inflammatory response could be potential targets of adjuvant therapy for ischemic stroke. Many studies have emphasized a well-established function of Annexin-A1 (ANXA1) in the immune system, including the regulation of microglial activation. Nevertheless, few therapeutic interventions targeting ANXA1 in microglia for ischemic stroke have been conducted. In the present study, Tat-NTS, a small peptide developed to prevent ANXA1 from entering the nucleus, was utilized. We discovered the underlying mechanism that Tat-NTS peptide targets microglial ANXA1 to protect against ischemic brain injury. Methods: Preclinical studies of ischemic stroke were performed using an oxygen-glucose deprivation and reperfusion (OGD/R) cell model in vitro and the middle cerebral artery occlusion (MCAO) animal model of ischemic stroke in vivo. Confocal imaging and 3D reconstruction analyses for detecting the protein expression and subcellular localization of microglia in vivo. Co-immunoprecipitation (Co-IP), immunoblotting, ELISA, quantitative real-time PCR (qRT-PCR), Luciferase reporter assay for determining the precise molecular mechanism. Measurement on the cytotoxicity of Tat-NTS peptide for microglia was assessed by CCK-8 and LDH assay. TUNEL staining was used to detect the microglia conditioned medium-mediated neuronal apoptosis. Adeno-associated viruses (AAVs) were injected into the cerebral cortex, striatum and hippocampal CA1 region of adult male Cx3cr1-Cre mice, to further verify the neurofunctional outcome and mechanism of Tat-NTS peptide by TTC staining, the modified Neurological Severity Score (mNSS) test, the open field test (OFT), the novel object recognition task (NORT), the Morris water maze (MWM) test, the long-term potentiation (LTP) and the Transmission electron microscopy (TEM). Results: It was observed that administration of Tat-NTS led to a shift of subcellular localization of ANXA1 in microglia from the nucleus to the cytoplasm in response to ischemic injury. Notably, this shift was accompanied by an increase in ANXA1 SUMOylation in microglia and a transformation of microglia towards an anti-inflammatory phenotype. We confirmed that Tat-NTS-induced ANXA1 SUMOylation in microglia mediated IKKα degradation via NBR1-dependent selective autophagy, then blocking the activation of the NF-κB pathway. As a result, the expression and release of the pro-inflammatory factors IL-1β and TNF-α were reduced in both in vitro and in vivo experiments. Furthermore, we found that Tat-NTS peptide's protective effect on microglia relieved ischemic neuron apoptosis. Finally, we demonstrated that Tat-NTS peptide administration, through induction of ANXA1 SUMOylation in microglia, reduced infarct volume, improved neurological function and facilitated behavioral recovery in MCAO mice. Conclusions: Our study provides evidence for a novel mechanism of Tat-NTS peptide in regulating microglial ANXA1 function and its substantial neuroprotective effect on neurons with ischemic injuries. These findings suggest that Tat-NTS peptides have a high potential for clinical application and may be a promising therapeutic candidate for treating cerebral ischemia.

Recombinant Human Perlecan DV and Its LG3 Subdomain Are Neuroprotective and Acutely Functionally Restorative in Severe Experimental Ischemic Stroke.

Despite recent therapeutic advancements, ischemic stroke remains a major cause of death and disability. It has been previously demonstrated that ~ 85-kDa recombinant human perlecan domain V (rhPDV) binds to upregulated integrin receptors (α2β1 and α5β1) associated with neuroprotective and functional improvements in various animal models of acute ischemic stroke. Recombinant human perlecan laminin-like globular domain 3 (rhPDVLG3), a 21-kDa C-terminal subdomain of rhPDV, has been demonstrated to more avidly bind to the α2β1 integrin receptor than its parent molecule and consequently was postulated to evoke significant neuroprotective and functional effects. To test this hypothesis, fifty male C57Bl/6J mice studied in a t-MCAO model were randomly allocated to either rhPDV treatment, rhPDVLG3, or equivalent volume of PBS at the time of reperfusion in a study where all procedures and analyses were conducted blind to treatment. On post-MCAO day 7, 2,3,5-triphenyltetrazolium chloride staining of brain slices was used to quantify infarct volume. We observed that treatment with rhPDVLG3 reduced infarct volume by 65.6% (p = 0.0001), improved weight loss (p < 0.05), and improved functional outcome measures (p < 0.05) when compared to PBS controls, improvements which were generally greater in magnitude than those observed for 2mg/kg of rhPDV. In addition, treatment with 6mg/kg of rhPDVLG3 was observed to significantly reduce mortality due to stroke in one model, an outcome not previously observed for rhPDV. Our initial findings suggest that treatment with rhPDVLG3 provides significant improvement in neuroprotective and functional outcomes in experimental stroke models and that further investigation of rhPDVLG3 as a novel neuroprotective therapy for patients with stroke is warranted.

H2S-mediated inhibition of RhoA/ROCK pathway and noncoding RNAs in ischemic stroke.

Ischemic stroke is one of major causes of disability. In the pathological process of ischemic stroke, the up-regulation of Ras homolog gene family, member A (RhoA) and its downstream effector, Ras homolog gene family (Rho)-associated coiled coil-containing kinase (ROCK), contribute to the neuroinflammation, blood-brain barrier (BBB) dysfunction, neuronal apoptosis, axon growth inhibition and astrogliosis. Accumulating evidences have revealed that hydrogen sulphide (H2S) could reduce brain injury in animal model of ischemic stroke via inhibiting the RhoA/ROCK pathway. Recently, noncoding RNAs (ncRNAs) such as circular RNAs (circRNAs), long noncoding RNAs (lncRNAs) and microRNAs (miRNAs) have attracted much attention because of their essential role in adjusting gene expression both in physiological and pathological conditions. Numerous studies have uncovered the role of RhoA/ROCK pathway and ncRNAs in ischemic stroke. In this review, we focused on the role of H2S, RhoA/ROCK pathway and ncRNAs in ischemic stroke and aimed to reveal new strategies for preventing and treating this devastating disease.

Dose-Dependent Von Willebrand Factor Inhibition by Aptamer BB-031 Correlates with Thrombolysis in a Microfluidic Model of Arterial Occlusion.

Von Willebrand Factor (VWF) plays a critical role in thrombus formation, stabilization, and propagation. Previous studies have demonstrated that targeted inhibition of VWF induces thrombolysis when administered in vivo in animal models of ischemic stroke. The study objective was to quantify dose-dependent inhibition of VWF-platelet function and its relationship with thrombolysis using BB-031, an aptamer that binds VWF and inhibits its function. VWF:Ac, VWF:RCo, T-TAS, and ristocetin-induced impedance aggregometry were used to assess BB-031-mediated inhibition of VWF. Reductions in original thrombus surface area and new deposition during administration of treatment were measured in a microfluidic model of arterial thrombolysis. Rotational thromboelastometry was used to assess changes in hemostasis. BB-031 induced maximal inhibition at the highest dose (3384 nM) in VWF:Ac, and demonstrated dose-dependent responses in all other assays. BB-031, but not vehicle, induced recanalization in the microfluidic model. Maximal lytic efficacy in the microfluidic model was seen at 1692 nM and not 3384 nM BB-031 when assessed by surface area. Minor changes in ROTEM parameters were seen at 3384 nM BB-031. Targeted VWF inhibition by BB-031 results in clinically measurable impairment of VWF function, and specifically VWF-GPIb function as measured by VWF:Ac. BB-031 also induced thrombolysis as measured in a microfluidic model of occlusion and reperfusion. Moderate correlation between inhibition and lysis was observed. Additional studies are required to further examine off-target effects of BB-031 at high doses, however, these are expected to be above the range of clinical targeted dosing.

Edaravone dexborneol provides neuroprotective benefits by suppressing NLRP3 inflammasome-induced microglial pyroptosis in experimental ischemic stroke

Edaravone dexborneol (EDB) is a traditional prescription that consists of two components, edaravone and (+)-borneol, which have synergistic antioxidant and anti-inflammatory activities in animal models of ischemic stroke. Pyroptosis is a form of cell death that has only recently been discovered. In this study, we investigated the therapeutic effects and potential mechanisms of EDB in acute ischemic stroke. We used an in vivo mouse transient middle cerebral artery occlusion (tMCAO) model along with an in vitro BV2 cell oxygen-glucose deprivation (OGD) model to perform specific experiments. The executive protein of pyroptosis, gasdermin D (GSDMD), was increased after tMCAO. The administration of EDB dramatically reduced sensorimotor deficits and infarct sizes in mice with tMCAO. In addition, EDB inhibited the production of the NLRP3-inflammasome and the activation of the NF-κB signaling pathway. This effect inhibited both the in vitro and in vivo expression of inflammatory factors, including IL-1β and IL-18. Collectively, our data indicate that EDB exerted positive effects after ischemic stroke. EDB inhibited the activation of NLRP3 inflammasome-induced microglial pyroptosis in experimental ischemic stroke. The findings of this research indicate that the NF-κB/NLRP3/GSDMD signaling pathway may serve as a therapeutic target for EDB to promote functional recovery after stroke.

Re-directing nanomedicines to the spleen: A potential technology for peripheral immunomodulation.

Modulation of peripheral immune cells in the spleen plays a key role in many life-threatening conditions such as stroke. Immune cell changes can lead to the excessive release of pro-inflammatory cytokines into the circulation and preferential loss of innate immune cells which can further exacerbate tissue damage and predispose patients to infectious complications. Reversing these processes represents an attractive treatment strategy and has shown to have beneficial effects in animal models of ischemic stroke, sepsis, traumatic brain injury (TBI) as well as myocardial infraction (MI). However, systemic interventions are often challenging to deliver due to the non-selective broad range of action of many treatments. More selective targeted treatment approaches are therefore desirable. The spleen is considered a natural filtration site for many nanomaterials due to the spontaneous tendency of this organ to filter blood-borne molecules. This selective targeting of nanomaterials to the spleen therefore offers considerable potential in the management of many conditions affected by peripheral inflammation. In this review, we will explore the key nanomaterials-related parameters that mediate splenic targeting and how these could influence the actual localization and function of nanomaterials once in the spleen. We aim to emphasize the potential of utilising nanomaterials as selective tools for peripheral immunomodulation to accelerate clinical translation.

Delivery of self-replicating messenger RNA into the brain for the treatment of ischemic stroke.

Ischemic stroke is caused by the occlusion of cerebral arteries. In the ischemic stroke, ischemia-reperfusion injury increases the damage in the brain after reperfusion. In the previous study, heme oxygenase-1 (HO1) mRNA was delivered into the ischemic brain, showing that HO1-mRNA had higher therapeutic effect and less side-effect than HO1-plasmid (pHO1). However, mRNA is degraded faster than plasmid DNA reducing the duration of gene expression. In this study, self-replicating mRNA (Rep-mRNA) was developed using a replicon system from Venezuelan Equine Encephalitis virus to compensate this disadvantage of mRNA delivery. Deoxycholic acid-conjugated polyethylenimine (DA-PEI) was used as a carrier of the mRNAs. The Rep-mRNA/DA-PEI complex had a size of around 90nm and a zeta-potential of 33mV. In the in vitro transfection assays, gene expression by the HO1-Rep-mRNA/DA-PEI complex persisted at least 14days, while that by the HO1-mRNA/DA-PEI complex approached basal level at 3days after transfection. Therapeutic effects of the HO1-Rep-mRNA/DA-PEI complexes were evaluated in the ischemic stroke animal model. The complexes were injected into the brain stereotaxically. HO1 expression by the HO1-Rep-mRNA/DA-PEI complex persisted at least 7days after injection, but the pHO1/DA-PEI or HO1-mRNA/DA-PEI complex showed basal level of HO1-expression at 7days after injection. Due to higher and longer expression of HO1, the apoptosis level and infarct size were decreased by the HO1-Rep-mRNA/DA-PEI complexes, compared with the pHO1/DA-PEI and HO1-mRNA/DA-PEI complex. These results suggest that HO1-Rep-mRNA/DA-PEI complex may have a potential as a long-lasting therapeutic system for the treatment of ischemic stroke.

Translating Animal Models of Ischemic Stroke to the Human Condition.

Ischemic stroke is a leading cause of death and disability. However, very few neuroprotective agents have shown promise for treatment of ischemic stroke in clinical trials, despite showing efficacy in many successful preclinical studies. This may be attributed, at least in part, to the incongruency between experimental animal stroke models used in preclinical studies and the manifestation of ischemic stroke in humans. Most often the human population selected for clinical trials are more diverse than the experimental model used in a preclinical study. For successful translation, it is critical to develop clinical trial designs that match the experimental animal model used in the preclinical study. This review aims to provide a comprehensive summary of commonly used animal models with clear correlates between rodent models used to study ischemic stroke and the clinical stroke pathologies with which they most closely align. By improving the correlation between preclinical studies and clinical trials, new neuroprotective agents and stroke therapies may be more accurately and efficiently identified.