Murine Stroke Model Research Articles

Role of STAT3-FOXO3 Signaling in the Modulation of Neuroplasticity by PD-L1-HGF-Decorated Mesenchymal Stem Cell-Derived Exosomes in a Murine Stroke Model.

The limited therapeutic strategies available for stroke leave many patients disabled for life. This study assessed the potential of programmed death-ligand 1 (PD-L1) and hepatocyte growth factor (HGF)-engineered mesenchymal stem cell-derived exosomes (EXO-PD-L1-HGF) in enhancing neurological recovery post-stroke. EXO-PD-L1-HGF, which efficiently endocytosed into target cells, significantly diminishes the H2O2-induced neurotoxicity and increased the antiapoptotic proteins in vitro. EXO-PD-L1-HGF attenuates inflammation by inhibiting T-cell proliferation and increasing the number of CD8+CD122+IL-10+ regulatory T cells. Intravenous injection of EXO-PD-L1-HGF could target stromal cell-derived factor-1α (SDF-1α+) cells over the peri-infarcted area of the ischemic brain through CXCR4 upregulation and accumulation in neuroglial cells post-stroke. EXO-PD-L1-HGF facilitates endogenous nestin+ neural progenitor cell (NPC)-induced neurogenesis via STAT3-FOXO3 signaling cascade, which plays a pivotal role in cell survival and neuroprotection, thereby mitigating infarct size and enhancing neurological recovery in a murine stroke model. Moreover, increasing populations of the immune-regulatory CD19+IL-10+ and CD8+CD122+IL-10+ cells, together with reducing populations of proinflammatory cells, created an anti-inflammatory microenvironment in the ischemic brain. Thus, innovative approaches employing EXO-PD-L1-HGF intervention, which targets SDF-1α+ expression, modulates the immune system, and enhances the activation of resident nestin+ NPCs, might significantly alter the brain microenvironment and create a niche conducive to inducing neuroplastic regeneration post-stroke.

Inhibition of sodium-glucose cotransporter-2 improves anaemia in mice and humans with sickle cell disease, and reduces infarct size in a murine stroke model.

Sodium-glucose cotransporter-2 (SGLT-2) is expressed in the kidney and may contribute to anaemia and cardiovascular diseases. The effect of SGLT-2 inhibition on anaemia and vascular endpoints in sickle cell disease (SCD) is unknown. A murine model of SCD was studied to determine the effects of the SGLT-2 inhibitor, empagliflozin, on anaemia and stroke size. The University of Michigan's Precision Health Database was used to evaluate the effect of SGLT-2 inhibitors on anaemia in humans with SCD. SCD mice treated with daily empagliflozin for 8 weeks demonstrated increases in haemoglobin, haematocrit, erythrocyte counts, reticulocyte percentage and erythropoietin compared to vehicle-treated mice. Following photochemical-induced thrombosis of the middle cerebral artery, mice treated with empagliflozin demonstrated reduced stroke size compared to vehicle treated mice. In the electronic health records analysis, haemoglobin, haematocrit and erythrocyte counts increased in human SCD subjects treated with an SGLT-2 inhibitor. SGLT-2 inhibitor treatment of humans and mice with SCD is associated with improvement in anaemic parameters. Empagliflozin treatment is also associated with reduced stroke size in SCD mice suggesting SGLT-2 inhibitor treatment may be beneficial with regard to both anaemia and vascular complications in SCD patients.

Alterations in visible light exposure modulate platelet function and regulate thrombus formation

BackgroundVariations in light exposure are associated with changes in inflammation and coagulation. The impact of light spectra on venous (VT) and arterial thrombosis is largely unexplored. ObjectivesTo investigate the impact of altering light spectrum on platelet function in thrombosis. MethodsWild type (WT) C57BL/6J mice were exposed to ambient (micewhite, 400lux), blue (miceblue, 442nm, 1,400lux), or red light (micered, 617nm, 1,400lux) with 12:12 hour light:dark cycle for 72 hours. After 72 hours of light exposure, platelet aggregation, activation, transcriptomic, and metabolomic changes were measured. The ability of released products of platelet activation to induce thrombosis-generating NET formation was quantified. Subsequent thrombosis was measured using murine models of VT and stroke. To translate our findings to human patients, light filtering cataract patients were evaluated over an 8-year period for rate of VTE with multivariable logistic regression clustered by hospital. ResultsExposure to long wavelength red light resulted in reduced platelet aggregation and activation. RNA-seq analysis demonstrated no significant transcriptomic changes between micered and micewhite. However, there were global metabolomic changes in platelets from micered compared to micewhite. Releasate from activated platelets resulted in reduced NET formation. Micered also had reduced VT weight and brain infarct size following stroke. On subgroup analysis of cataract patients, patients with a history of cancer have lower lifetime risk of VTE after implantation with lenses that filter low wavelength light. ConclusionsLight therapy may be a promising approach to thrombus prophylaxis by specifically targeting the intersection between innate immune function and coagulation.

Plasminogen activator inhibitor-1 mediates cerebral ischemia-induced astrocytic reactivity.

Although ischemia increases the abundance of plasminogen activator inhibitor-1 (PAI-1), its source and role in the ischemic brain remain unclear. We detected PAI-1-immunoreactive cells with morphological features of reactive astrocytes in the peri-ischemic cortex of mice after an experimentally-induced ischemic lesion, and of a chimpanzee that suffered a naturally-occurring stroke. We found that although the abundance of PAI-1 increases 24 hours after the onset of the ischemic injury in a non-reperfusion murine model of ischemic stroke, at that time-point there is no difference in astrocytic reactivity and the volume of the ischemic lesion between wild-type (Wt) animals and in mice either genetically deficient (PAI-1-/-) or overexpressing PAI-1 (PAI-1Tg). In contrast, 72 hours later astrocytic reactivity and the volume of the ischemic lesion were decreased in PAI-1-/- mice and increased in PAI-1Tg animals. Our immunoblottings and fractal analysis studies show that the abundance of astrocytic PAI-1 rises during the recovery phase from a hypoxic injury, which in turn increases the abundance of glial fibrillary acidic protein (GFAP) and triggers morphological features of reactive astrocytes. These studies indicate that cerebral ischemia-induced release of astrocytic PAI-1 triggers astrocytic reactivity associated with enlargement of the necrotic core.

Inhibition of neutrophil rolling and migration by caADAMTS13 in vitro and in mouse models of thrombosis and inflammation

Recent investigation of a constitutively active ADAMTS13 variant (caADAMTS13) in murine models of acute ischaemic stroke (AIS) have revealed a potential anti-inflammatory mechanism of action contributing to its protective effect. However, it remains unclear whether these observations are a direct result of VWF proteolysis by caADAMTS13. We have implemented state of the art in vitro assays of neutrophil rolling and transmigration to quantify the impact of caADAMTS13 on these processes. Moreover, we have tested caADAMTS13 in two in vivo assays of neutrophil migration to confirm the impact of the treatment on the neutrophil response to sterile inflammation. Neutrophil rolling, over an interleukin-1β stimulated hCMEC/D3 monolayer, is directly inhibited by caADAMTS13, reducing the proportion of neutrophils rolling to 9.5 ± 3.8 % compared to 18.0 ± 4.5 % in untreated controls. Similarly, neutrophil transmigration recorded in real-time, was significantly suppressed in the presence of caADAMTS13 which reduced the number of migration events to a level like that in unstimulated controls (18.0 ± 4.5 and 15.8 ± 7.5 cells/mm2/h, respectively). Brain tissue from mice undergoing experimental focal cerebral ischaemia has indicated the inhibition of this process by caADAMTS13. This is supported by caADAMTS13’s ability to reduce neutrophil migration into the peritoneal cavity in an ischaemia-independent model of sterile inflammation, with the VWF-dependent mechanism by which this occurs being confirmed using a second experimental stroke model. These findings will be an important consideration in the further development of caADAMTS13 as a potential therapy for AIS and other thromboinflammatory pathologies, including cardiovascular disease.

Dim light at night shifts microglia to a pro-inflammatory state after cerebral ischemia, altering stroke outcome in mice

Circadian rhythms are endogenous biological cycles that regulate physiology and behavior and are set to precisely 24-h by light exposure. Light at night (LAN) dysregulates physiology and function including immune response; a critical component that contributes to stroke pathophysiological progression of neuronal injury and may impair recovery from injury. The goal of this study is to explore the effects of dim LAN (dLAN) in a murine model of ischemic stroke to assess how nighttime lighting from hospital settings can affect stroke outcome. Further, this study sought to identify mechanisms underlying pathophysiological changes to immune response after circadian disruption. Male and female adult Swiss Webster (CFW) mice were subjected to transient or permanent focal cerebral ischemia, then were subsequently placed into either dark night conditions (LD) or one night of dLAN (5 lx). 24 h post-stroke, sensorimotor impairments and infarct sizes were quantified. A single night of dLAN following MCAO increased infarct size and sensorimotor deficits across both sexes and reduced survival in males after 24 h. Flow cytometry was performed to assess microglial phenotypes after MCAO, and revealed that dLAN altered the percentage of microglia that express pro-inflammatory markers (MHC II+ and IL-6) and microglia that express CD206 and IL-10 that likely contributed to poor ischemic outcomes. Following these results, microglia were reduced in the brain using Plexxikon 5622 (PLX 5622) a CSFR1 inhibitor, then the mice received an MCAO and were exposed to LD or dLAN conditions for 24 h. Microglial depletion by PLX5622 resulted in infarct sizes that were comparable between lighting conditions. This study provides supporting evidence that environmental lighting exacerbates ischemic injury and post-stroke mortality by a biological mechanism that exposure to dLAN causes a fundamental shift of activated microglial phenotypes from beneficial to detrimental at an early time point after stroke, resulting in irreversible neuronal death.

507 Neuroprotective Effects of a Steroid Receptor Coactivator Stimulator in a Murine Model of Acute Ischemic Stroke with Reperfusion

INTRODUCTION: Stroke is the leading cause of adult disability and the fifth leading cause of mortality in the United States. Despite the study of many neuroprotective agents for acute ischemic stroke, none has been shown to be effective in large randomized clinical trials. Steroid receptor coactivator (SRC) is a promising class of agents since they are involved in cellular proliferation and regeneration, immune modulation, angiogenesis, antioxidant protection and are expressed in the brain. METHODS: Twenty c57bl/6 mice were randomly assigned to control or treatment groups (n = 10 mice per group). All mice underwent middle cerebral artery occlusion for 90 minutes followed by reperfusion via the intraluminal filament method. Occlusion was confirmed by laser doppler flowmetry. Intraperitoneal injections of saline (control) or 10-1 (treatment) were given 30 minutes after reperfusion. Each animal was tested using a modified Bederson’s neurological deficit scale (mNDS) and euthanized at the conclusion of the 24-hour survival period. Brain slices were stained with 2,3,5- triphenyltetrazolium chloride (TTC) to identify ischemic brain tissue. RESULTS: When compared with the control group, 10-1 treated mice showed significantly lower mNDS scores (p = 0.000336) and incidence of circling (p = 0.00256). Calculated infarct volumes, based on TTC staining, of the 10-1 treated group were significantly lower (p = 0.0009) when compared to the control group. CONCLUSIONS: We have shown that 10-1 is a promising therapeutic agent and provides substantial neuroprotection through its many multicellular processes in a rodent study. Current studies are being conducted to investigate the mechanism of 10-1 as neuroprotectant.

Inhibition of Anaplastic Lymphoma Kinase Protects From Ischemic Stroke.

Ischemic stroke is often accompanied by oxidative stress and inflammatory response, both of which work synergistically to exacerbate the disruption of the blood-brain barrier and ischemic brain injury. ALK (anaplastic lymphoma kinase), a cancer-associated receptor tyrosine kinase, was found to play a role in oxidative stress and inflammation. In this study, we investigated the role of ALK inhibition in a murine model of ischemic stroke. Focal cerebral ischemia was induced by temporary occlusion of the right middle cerebral artery in mice with a filament. The ALK inhibitor alectinib was administered following the stroke. ALOX15 (arachidonic acid 15-lipoxygenase) was overexpressed by adenovirus injection. The immunohistochemistry, Western blot, oxidative stress, inflammation, blood-brain barrier leakage, infarct volume, and functional outcomes were determined. We found that the expression of ALK was markedly increased in the neurovascular unit after cerebral ischemia. Treatment with the ALK inhibitor alectinib reduced the accumulation of reactive oxygen species, lipid peroxidation, and oxidative DNA, increased the vascular levels of antioxidant enzymes, inactivated the vascular NLRP3 (nucleotide-binding oligomerization domain-like receptor protein 3) inflammasome pathway, and reduced vascular inflammation (ICAM-1 [intercellular adhesion molecule-1] and MCP-1 [monocyte chemoattractant protein-1]) after ischemia. Moreover, alectinib reduced the loss of cerebrovascular integrity and blood-brain barrier damage, consequently decreasing brain infarction and neurological deficits. Furthermore, alectinib reduced stroke-evoked ALOX15 expression, whereas virus-mediated overexpression of ALOX15 abolished alectinib-dependent inhibition of oxidative stress and vascular inflammation, blood-brain barrier protection, and neuroprotection, suggesting the protective effects of alectinib for stroke may involve ALOX15. Our findings demonstrated that alectinib protects from stroke by regulating ischemic signaling cascades and suggest that ALK may be a novel therapeutic target for ischemic stroke.

"The Neuroprotection Effect of GLP-1 Receptor in Murine Stroke Model"

"The Neuroprotection Effect of GLP-1 Receptor in Murine Stroke Model"

Integrating spatial and single-cell transcriptomics to characterize the molecular and cellular architecture of the ischemic mouse brain.

Neuroinflammation is acknowledged as a pivotal pathological event after cerebral ischemia. However, there is limited knowledge of the molecular and spatial characteristics of nonneuronal cells, as well as of the interactions between cell types in the ischemic brain. Here, we used spatial transcriptomics to study the ischemic hemisphere in mice after stroke and sequenced the transcriptomes of 19,777 spots, allowing us to both visualize the transcriptional landscape within the tissue and identify gene expression profiles linked to specific histologic entities. Cell types identified by single-cell RNA sequencing confirmed and enriched the spatial annotation of ischemia-associated gene expression in the peri-infarct area of the ischemic hemisphere. Analysis of ligand-receptor interactions in cell communication revealed galectin-9 to cell-surface glycoprotein CD44 (LGALS9-CD44) as a critical signaling pathway after ischemic injury and identified microglia and macrophages as the main source of galectins after stroke. Extracellular vesicle-mediated Lgals9 delivery improved the long-term functional recovery in photothrombotic stroke mice. Knockdown of Cd44 partially reversed these therapeutic effects, inhibiting oligodendrocyte differentiation and remyelination. In summary, our study provides a detailed molecular and cellular characterization of the peri-infact area in a murine stroke model and revealed Lgals9 as potential treatment target that warrants further investigation.

Abstract WP294: Endothelial Deletion of Complement C3a Receptor is Neuroprotective in Murine Stroke

Background: Stroke is among the leading causes of death and disability worldwide. We and others have shown that endothelial C3a receptor (C3aR) expression is enhanced in murine stroke models as well as in OGD induced brain endothelial cells. Therefore, it is critical to investigate the role of endothelial C3aR in post-stroke neurovascular dysfunction. Hypothesis: Genetic ablation of endothelial C3aR will afford neuroprotection in stroke. Methods: We used a loxP-cre approach (C3aR Flox/Flox x Cdh5 Cre ) to generate conditional C3aR endothelial deficient or sufficient mice (C3aR Endo+/+ or C3aR Endo-/- ) of both sexes (3-4 months old) which were subjected to photothrombotic stroke. WT littermates were used as controls. We assessed cerebral blood flow (CBF), Infarct volume, BBB integrity, and myeloid cell infiltration. Neurobehavioral functions were tested at 3 and 21 days. P<0.05 was considered statistically significant. Results: Photothrombotic (PT) stroke resulted in decreased CBF in C3aR Endo +/+ mice compared with sham animals. However, infarct volume and CBF were improved after 72 h post PT in C3aR Endo-/- vs C3aR Endo +/+ . C3aR Endo-/- mice showed improved motor and cognitive function when compared with C3aR Endo+/+ . Furthermore, reduced myeloid cell/neutrophil infiltration and improved BBB integrity in C3aR Endo -/- vs C3aR Endo+/+ were observed. Conclusion: Genetic deletion of C3aR expression from endothelial cells is neuroprotective in a PT murine stroke model through suppression of inflammation. Further work is warranted to explore underlying mechanisms of C3aR mediated brain injury in stroke.

Abstract WMP117: Altered Patterns of microRNA 9-3p in Acute Ischemic Stroke With Large Vessel Occlusion

Background: Stroke is a significant health issue in the United States, and identifying biomarkers for preventing acute ischemic stroke (AIS) remains the highest priority. This study aims to identify microRNA (miRNA) associated with AIS pathophysiology through longitudinal and case-control studies. Methods: We examined global miRNA profiles of serum exosome vesicles of 15 patients with a large vessel occlusion (LVO) using NextGen sequencing. Discovery cohort consisted of miRNA profiles collected during acute (<72 hours, T1) and chronic (3-5 months, T2) stroke stages. The preliminary results were validated through Validation set-1 included 55 LVO cases and 53 controls. and Validation set-2 comprised 15 LVO patients collected at different time points <24h-A1, 48-72h-A2, 5-7 days-A3, >3 months-A4. Results: Our study identified four miRNAs, miR-9-3p, miR-129-5p, miR-223-3p, and miR-423-5p, with differential expressions in LVOs compared to controls. Exosomal miR-9-3p showed a 14.7-fold increase in T1 (Bonferroni p= 9.4x10 -6 ) in the Discovery set and a 9.39-fold increase (Bonferroni p= 1.3x10 -4 ) in stroke cases compared to controls in the Validation-set-1. In the longitudinal analysis of Validation set-2, miR-9-3p levels peaked significantly at A2 and then gradually decreased over A3 and A4 time points. Though miR-129-5p and miR-423-5p were also significantly upregulated during the T1, their association did not survive the stringent Bonferroni correction in any sets. Discussion and Conclusion: MiR-9-3p triggers brain injury via caspase pathway in the murine stroke model. Its role in human AIS pathophysiology is not available. For the first time, we report the possible contribution of miR-9-3p during the acute state in LVO strokes. The pathway analysis suggests miR-9-3p may lead to neuronal cell death and apoptosis in AIS. If confirmed, therapeutic targeting of miRNA 9-3p may become clinically useful biomarkers for treating LVO in humans. Funding: College of Medicine Alumni Association, the Presbyterian Health Foundation, Leinbach Foundation grants, and Dr. Geoffrey Altshuler Endowment funds from the Children’s Health Foundation of OUHSC, and partly supported by National Institute of Health (NIH/NIDDK) R01DK118427 grant.

Abstract TP309: Cortical Extravasation of Neutrophils and Unexpected Persistence Following Ischemia/Reperfusion in a Murine Ischemic Stroke Model

Background and Purpose: Neutrophils are the first recruited leukocytes following ischemia/reperfusion injury in the brain; however, when and where neutrophils enter the brain parenchyma to exert their effects is controversial. Understanding the spatiotemporal underpinnings of leukocyte extravasation is required to advance therapeutic interventions. Here we describe the complex evolution of neutrophil recruitment and extravasation following ischemic stroke. Methods: Circulating neutrophils were pulse-labeled with EdU to track specific cells recruited post stroke. The transient middle cerebral artery occlusion (tMCAO) model was used to simulate large vessel occlusion and reperfusion. Coronal sections were examined at various timepoints and the position of EdU-labeled neutrophils was precisely determined by fluorescence microscopy. PECAM antibody treatment was used to disrupt neutrophil extravasation at the cortical surface and alter migration kinetics. Results: At early timepoints, 12 h and 24 h, neutrophil recruitment was unexpectedly superficial. Over 120 h, neutrophils were found increasingly deeper into the subcortex. Timing of tMCAO surgery with EdU labeling allowed for specific labeling of the initial wave of neutrophils. Surprisingly, many EdU positive neutrophils were still observed at 72 h, indicating they had survived for several days. The number and distribution of EdU positive neutrophils confirms the majority of neutrophil recruitment occurs before 24 h across the infarct. Disrupting leukocyte extravasation with PECAM function-blocking antibodies restricted neutrophils to the cortical surface. Conclusions: Our findings demonstrate that neutrophil infiltration post stroke evolves over several days. This data suggests neutrophils are recruited to the infarct within the first 24 h, enter the brain at the cortical surface, distribute throughout the infarct, and persist over 72 h. Furthermore, disrupting extravasation with PECAM antibodies modulates neutrophil progression into the infarct. A better understanding of leukocyte spatiotemporal infiltration and its regulators will help inform future therapeutic interventions targeting leukocytes.

Opto-Lipidomics of Tissues.

Lipid metabolism and signaling play pivotal functions in biology and disease development. Despite this, currently available optical techniques are limited in their ability to directly visualize the lipidome in tissues. In this study, opto-lipidomics, a new approach to optical molecular tissue imaging is introduced. The capability of vibrational Raman spectroscopy is expanded to identify individual lipids in complex tissue matrices through correlation with desorption electrospray ionization (DESI) - mass spectrometry (MS) imaging in an integrated instrument. A computational pipeline of inter-modality analysis is established to infer lipidomic information from optical vibrational spectra. Opto-lipidomic imaging of transient cerebral ischemia-reperfusion injury in a murine model of ischemic stroke demonstrates the visualization and identification of lipids in disease with high molecular specificity using Raman scattered light. Furthermore, opto-lipidomics in a handheld fiber-optic Raman probe is deployed and demonstrates real-time classification of bulk brain tissues based on specific lipid abundances. Opto-lipidomics opens a host of new opportunities to study lipid biomarkers for diagnostics, prognostics, and novel therapeutic targets.

Oligodendrocyte progenitor cell-specific delivery of lipid nanoparticles loaded with Olig2 synthetically modified messenger RNA for ischemic stroke therapy

The transcription factor Olig2 is highly expressed throughout oligodendroglial development and is needed for the differentiation of oligodendrocyte progenitor cells (OPCs) into oligodendrocytes and remyelination. Although Olig2 overexpression in OPCs is a possible therapeutic target for enhancing myelin repair in ischemic stroke, achieving Olig2 overexpression in vivo remains a formidable technological challenge. To address this challenge, we employed lipid nanoparticle (LNP)-mediated delivery of Olig2 synthetically modified messenger RNA (mRNA) as a viable method for in vivo Olih2 protein overexpression. Specifically, we developed CD140a-targeted LNPs loaded with Olig2 mRNA (C-Olig2) to achieve targeted Olig2 protein expression within PDGFRα+ OPCs, with the goal of promoting remyelination for ischemic stroke therapy. We show that C-Olig2 promotes the differentiation of PDGFRα+ OPCs derived from mouse neural stem cells into mature oligodendrocytes in vitro, suggesting that mRNA-mediated Olig2 overexpression is a rational approach to promote oligodendrocyte differentiation and remyelination. Furthermore, when C-Olig2 was administered to a murine model of ischemic stroke, it led to improvements in blood‒brain barrier (BBB) integrity, enhanced remyelination, and rescued learning and cognitive deficits. Our comprehensive analysis, which included bulk RNA sequencing (RNA-seq) and single-nucleus RNA-seq (snRNA-seq), revealed upregulated biological processes related to learning and memory in the brains of mice treated with C-Olig2 compared to those receiving empty LNPs (Mock). Collectively, our findings highlight the therapeutic potential of multifunctional nanomedicine targeting mRNA expression for ischemic stroke and suggest that this approach holds promise for addressing various brain diseases. Statement of significanceWhile Olig2 overexpression in OPCs represents a promising therapeutic avenue for enhancing remyelination in ischemic stroke, in vivo strategies for achieving Olig2 expression pose considerable technological challenges. The delivery of mRNA via lipid nanoparticles is considered aa viable approach for in vivo protein expression. In this study, we engineered CD140a-targeted LNPs loaded with Olig2 mRNA (C-Olig2) with the aim of achieving specific Olig2 overexpression in mouse OPCs. Our findings demonstrate that C-Olig2 promotes the differentiation of OPCs into oligodendrocytes in vitro, providing evidence that mRNA-mediated Olig2 overexpression is a rational strategy to foster remyelination. Furthermore, the intravenous administration of C-Olig2 into a murine model of ischemic stroke not only improved blood-brain barrier integrity but also enhanced remyelination and mitigated learning and cognitive deficits. These results underscore the promising therapeutic potential of multifunctional nanomedicine targeting mRNA expression in the context of ischemic stroke.

Specific inhibition on PAI-1 reduces the dose of Alteplase for ischemic stroke treatment

Administration of recombinant tPA (rtPA, or trade name Alteplase®) is an FDA-approved therapy for acute ischemic stroke (AIS), but poses the risk of hemorrhagic complications. Recombinant tPA can be rapidly inactivated by the endogenous inhibitor, plasminogen activator inhibitor 1 (PAI-1). In this work, we study a novel treatment approach that combines a PAI-1 inhibitor, PAItrap4, with a reduced dose of rtPA to address the hemorrhagic concern of rtPA. PAItrap4 is a highly specific and very potent protein-based inhibitor of PAI-1, comprising of a variant of uPA serine protease domain, human serum albumin, and a cyclic RGD peptide. PAItrap4 efficiently targets and inhibits PAI-1 on activated platelets, and also possesses a long half-life in vivo. Our results demonstrate that PAItrap4 effectively counteracts the inhibitory effects of PAI-1 on rtPA, preserving rtPA activity based on amidolytic and clot lysis assays. In an in vivo murine stroke model, PAItrap4, together with low-dose rtPA, enhances the blood perfusion in the stroke-affected areas, reduces infarct size, and promotes neurological recovery in mice. Importantly, such treatment does not increase the amount of cerebral hemorrhage, thus reducing the risk of cerebral hemorrhage. In addition, PAItrap4 does not compromise the normal blood coagulation function in mice, demonstrating its safety as a therapeutic agent. These findings highlight this combination therapy as a promising alternative for the treatment of ischemic stroke, offering improved safety and efficacy.

Novel Programmed Death Ligand 1-AKT-engineered Mesenchymal Stem Cells Promote Neuroplasticity to Target Stroke Therapy.

Although tissue plasminogen activator (t-PA) and endovascular thrombectomy are well-established treatments for acute ischemic stroke, over half of patients with stroke remain disabled for a long time. Thus, a significant unmet need exists to develop an effective strategy for treating acute stroke. We developed a combination of programmed cell death-ligand 1 (PD-L1) and AKT-modified umbilical cord mesenchymal stem cells (UMSC-PD-L1-AKT) implanted through intravenous (IV) and intracarotid (IA) routes to enhance therapeutic efficacy in a murine stroke model for overcoming the hypoxic environment of the ischemic brain, to prolong stem cell survival, and to attenuate systemic inflammation to protect neuroglial cells from ischemic injury. Higher cellular proliferation and survival upon exposure to toxic agents were observed in UMSC-PD-L1-AKT cells than in UMSCs in vitro. Moreover, increased attenuation of CFSE+ cell proliferation and increased survival of primary cortical cells were verified by the interaction with UMSC-PD-L1-AKT. Consistently, dual-route administration (IV + IA) of UMSC-PD-L1-AKT resulted in a significant reduction in infarction volume and improvement of neurological dysfunction in a stroke model. Furthermore, enhancing CD8+CD122+IL-10+ T-regulatory (Treg) cells and reducing CD11b+CD80+ microglial/macrophages and CD3+CD8+TNF-α+ and CD3+CD8+ IFN-α+ cytotoxic T cells induced an anti-inflammatory microenvironment to protect neuroglial cells in the ischemic brain. Collectively, therapeutic intervention using UMSC-PD-L1-AKT could provide a niche for inducing neuroplastic regeneration in brains after stroke.

Intranasal Delivery of Mitochondria Attenuates Brain Injury by AMPK and SIRT1/PGC-1α Pathways in a Murine Model of Photothrombotic Stroke.

Ischemic stroke is one of the major causes of morbidity and mortality worldwide. Mitochondria play a vital role in the pathological processes of cerebral ischemic injury, but its transplantation and underlying mechanisms remain unclear. In the present study, we examined the effects of mitochondrial therapy on the modulation of AMPK and SIRT1/PGC-1α signaling pathway, oxidative stress, and NLRP3 inflammasome activation after photothrombotic ischemic stroke (pt-MCAO). The adult male mice were subjected to the pt-MCAO in which the proximal-middle cerebral artery was exposed with a 532-nm laser beam for 4 min by retro-orbital injection of a photosensitive dye (Rose Bengal: 15 mg/kg) before the laser light exposure and isolated mitochondria (100 μg protein) were administered intranasally at 30 min, 24 h, and 48 h following post-stroke. After 72 h, mice were tested for neurobehavioral outcomes and euthanized for infarct volume, brain edema, and molecular analysis. First, we found that mitochondria therapy significantly decreased brain infarct volume and brain edema, improved neurological dysfunction, attenuated ischemic stroke-induced oxidative stress, and neuroinflammation. Second, mitochondria treatment inhibited NLRP3 inflammasome activation. Finally, mitochondria therapy accelerated p-AMPKα(Thr172) and PGC-1α expression and resorted SIRT1 protein expression levels in pt-MCAO mice. In conclusion, our results demonstrate that mitochondria therapy exerts neuroprotective effects by inhibiting oxidative damage and inflammation, mainly dependent on the heightening activation of the AMPK and SIRT1/PGC-1α signaling pathway. Thus, intranasal delivery of mitochondria might be considered a new therapeutic strategy for ischemic stroke treatment.

OC 53.1 Magnetically Powered Microwheels Enhance Thrombolysis in a Murine Model of Ischemic Stroke

OC 53.1 Magnetically Powered Microwheels Enhance Thrombolysis in a Murine Model of Ischemic Stroke

A modified murine photothrombotic stroke model: a minimally invasive and reproducible cortical and sub-cortical infarct volume and long-term deficits.

Ischemic stroke is one of the major causes of devastating neurological disabilities and mortality worldwide. Despite extensive research for treatment approaches, there remains limited therapy in the stroke field. Therefore, more research is required for reproducibility to understand stroke pathology in pre-clinical studies. In the current modified method, mice were subjected to photothrombotic stroke (pt-MCA; proximal-middle cerebral artery was exposed with a 532nm laser beam for 4min) by retro-orbital injection of photosensitive dye, Rose Bengal (15mg/kg) before the laser light exposure. Sensorimotor deficits were assessed by rotarod and catwalk test at 72h following post-pt-MCAO, and brain samples were collected for infarct volume and hemorrhagic transformation (HT) assessments. Cognitive impairments were assessed by a novel objective recognition and Morris's water maze tests at the end of the follow-up. pt-MCAO animals significantly reduced body weight and impaired motor and cognitive functions. Furthermore, pt-MCAO animals showed apparent infarction, brain edema, and increased HT compared to the sham animals. Additionally, this method enables concurrent measurement of short-term and long-term neurological dysfunction with relatively larger cortical and sub-cortical infarct volume following pt-MCAO. With respect to the other models, this modified model offers enhanced reproducibility regarding infarct volume and cognitive/functional outcomes and avoids complications associated with critical surgeries and craniotomy. In conclusion, this modified model helps to understand stroke pathogenesis and minimize the animals' numbers which help to increase the scientific and statistical potential in pre-clinical studies.