Ischemia Model Research Articles

Development of transient ischemic attack risk prediction model suitable for initializing a learning health system unit using electronic medical records

BackgroundPatients with transient ischemic attack (TIA) face a significantly increased risk of stroke. However, TIA screening and early detection rates are low, especially in developing countries. This study aims to develop an inclusive and practical TIA risk prediction model using machine learning (ML) that performs well in both hospital and resource-limited clinic settings. This model is essential for initiating the first ML-enabled learning health system (LHS) unit designed for routine and equitable TIA screening and early detection across broad populations.MethodsEmploying a novel protocol, this study first standardized data from a hospital’s electronic medical records (EMR) to construct inclusive TIA risk prediction ML models using a data-centric approach. Subsequently, a quantitative distribution of TIA risk factors was applied in feature engineering to reduce the number of variables for a practical ML model. This refined model initiated a TIA ML-LHS unit that is capable of continuously updating with new EMR data from hospitals and clinics. Additionally, the practical model underwent external validation using data from another hospital.ResultsThe inclusive 150-variable ML models, derived from all available EMR variables for TIA, achieved a recall of 0.868 and an accuracy of 0.886 in predicting TIA risk. Further feature engineering produced a practical XGBoost model with 20 variables, maintaining acceptable performance of 0.855 recall and 0.796 accuracy. The initialized TIA ML-LHS unit, based on the practical model, achieved performance metrics of 0.830 recall, 0.726 precision, 0.816 ROC-AUC, and 0.812 accuracy. The model also performed well in external validation, confirming its effectiveness with patient data from different clinical settings.ConclusionsThis study developed the first inclusive and practical TIA XGBoost model from full hospital EHR and initiated the first TIA risk prediction ML-LHS unit. This TIA model, which requires only 20 variables, enables the ML-LHS to serve not only patients in hospitals but also those in resource-limited clinics. These results have significant implications for expanding risk-based TIA screening in community and rural clinics, thereby enhancing early detection of TIA among underserved populations and improving health equity. The novel protocol used in this study is also applicable for initiating ML-LHS units for various preventable diseases, providing a new system-level approach to responsible AI development and applications.

Secretome from hypoxic mesenchymal stem cells as a potential therapy for ischemic stroke: Investigations on VEGF and GFAP expression

Ischemic stroke is a sudden onset of neurological deficit resulting from a blockage in cerebral blood vessels, which can lead to brain tissue damage, chronic disability, and increased risk of mortality. Secretome from hypoxic mesenchymal stem cells (SH-MSC) is a potential therapy to improve neurological deficit by increasing the expression of vascular endothelial growth factor (VEGF) and reducing glial fibrillary acidic protein (GFAP). These effects can reduce the infarction area of ischemic stroke. Therefore, the aim of this study was to analyze the effect of 150 μL and 300 μL SH-MSC injection on VEGF and GFAP expression as well as the improvement of infarction area in ischemic stroke animal model. A post-test-only experimental design with consecutive sampling was used, with Rattus norvegicus as subjects. Stromal mesenchymal stem cells (S-MSCs) were isolated from the umbilical cords of rats at 21 days of gestation. Secretome production by the S-MSCs was induced under a hypoxic condition, and subsequently isolated. The resultant secretome was administered to rats subjected to middle cerebral artery occlusion (MCAO) at doses of 150 μL (P1 group) and 300 μL (P2 group). The results showed that the infarction area was reduced in P1 (p<0.001) and P2 groups (p<0.001). SH-MSC at a dose of 300 μL increased the expression of VEGF (p=0.028) and reduced the expression of GFAP (p=0.001). In conclusion, secretome from hypoxic S-MSC could potentially improve ischemic stroke by upregulating VEGF expression and downregulating GFAP expression.

Content of Nitrogen Monoxide and Copper in the Hippocampus of a Rat Model of Short-Term Cerebral Ischemia Followed by Reperfusion

Content of Nitrogen Monoxide and Copper in the Hippocampus of a Rat Model of Short-Term Cerebral Ischemia Followed by Reperfusion

New alternative approaches to stroke treatment: the blood cell–derived secretome shows promise in individuals with obesity

Ischaemic tolerance induced by remote ischaemic conditioning (RIC) has been extensively demonstrated in several preclinical models of cerebral ischaemia. However, animals with common stroke-related comorbidities do not benefit from the recent advances of RIC. Therefore, we investigated two alternative approaches for obese animals with stroke: (1) the efficacy of an additional round of the standard RIC protocol, and (2) the paracrine potential of the blood cell–derived secretome derived from RIC-induced healthy young rats. We found that a second round of remote ischaemic postconditioning (RIPostC) stimulus reduced neurodegeneration and exerted antioxidant effects but failed to decrease the infarct volume and alter glutamate homeostasis. However, when obese rats were administered the secretome from healthy, young RIC-stimulated rats, they exhibited improved neurological post-stroke outcomes. Intravenous administration of the tolerant secretome activated several endogenous mechanisms, including a reduction in the infarct volume and neurodegeneration in the penumbra. Furthermore, the blood cell–derived secretome accelerated brain-to-blood glutamate efflux in obese rats, and demonstrated antioxidant properties that may have contributed to the induction of tolerance in obese rats with stroke. These findings indicate that the blood cell–derived secretome has unique abilities and represents a new potential treatment for individuals with obesity and ischaemic stroke.

Quantification of hemi-hepatic ischemia using real-time multispectral oxygenation imaging with single snapshot imaging of optical properties (SSOP).

Identifying liver ischemia is crucial in liver surgery. This study aimed to develop a hemi-hepatic ischemia model for assessing liver ischemia using single snapshot imaging of optical properties (SSOP), a noninvasive optical imaging modality that provides real-time measurements of tissue oxygen saturation (StO2). Twelve swine were randomly assigned to two groups: One undergoing total vascular inflow occlusion (TVIO) and the other undergoing hepatic artery occlusion (HAO). Preoperative 3D CT scans were used to locate the left-sided hepatic arteries and portal veins, which were clamped during surgery. Real-time SSOP imaging was conducted to measure StO2 in three lobes-the left lateral lobe (LL), left medial lobe (LM), and right medial lobe (RM)-as well as capillary lactate levels and Doppler blood flow. Measurements were recorded at baseline (T0), during ischemia (T1, 30min after clamping), and during reperfusion (T2, 30min after declamping). In the TVIO group, SSOP imaging revealed a distinct demarcation line on the liver surface. StO2 levels measured by SSOP significantly decreased from T0 to T1, dropping by 29.8% in the LL (46.0 ± 5.1 vs. 16.2 ± 5.1%, p = 0.011) and 36.3% in the LM (42.7 ± 5.9 vs. 6.4 ± 4.0%, p = 0.001). Additionally, capillary lactate levels increased substantially in the LL (1.3 ± 0.4 vs. 8.5 ± 2.4mmol/L, p = 0.041) and in the LM (1.3 ± 0.4 vs. 8.2 ± 2.1mmol/L, p = 0.021). In contrast, the HAO group showed a less pronounced reduction in StO2: 13.6% in the LL (32.7 ± 6.4 vs. 19.1 ± 5.4%, p = 0.007) and 19.8% in the LM (35.3 ± 8.2 vs. 15.5 ± 5.8%, p = 0.011), with no significant increase in capillary lactate levels. An inverse correlation was found between StO2 and capillary lactate levels (r = -0.76, p < 0.001). SSOP is a real-time, contrast-free imaging technique that effectively evaluates liver ischemia by accurately measuring tissue oxygenation, as validated by perfusion biomarkers.

Low dose Adenoviral Vammin gene transfer induces myocardial angiogenesis and increases left ventricular ejection fraction in ischemic porcine heart

This preliminary study investigated if VEGFR-2 selective adenoviral Vammin (AdVammin) gene therapy could induce angiogenesis and increase perfusion in the healthy porcine myocardium. Also, we determined using a clinically relevant large animal model if AdVammin gene therapy could improve the function of a chronically ischemic heart. Low doses of AdVammin (dose range 2 × 109–2 × 1010 vp) gene transfers were performed into the porcine myocardium using an endovascular injection catheter. AdCMV was used as a control. The porcine model of chronic myocardial ischemia was used in the ischemic studies. The AdVammin enlarged the mean capillary area and stimulated pericyte coverage in the target area 6 days after the gene transfers. Using positron emission tomography 15O-radiowater imaging, we demonstrated that AdVammin gene therapy increased perfusion in healthy myocardium at rest. AdVammin treatment also increased ejection fraction at stress in the ischemic heart, as detected using left ventricular cine angiography. In addition, we demonstrated successful in vivo imaging of enhanced angiogenesis using [68Ga]NODAGA-RGD peptide. However, AdVammin also increased tissue permeability and was associated with significant pericardial fluid accumulation, limiting AdVammin’s therapeutic potential and emphasizing the importance of correct dosage.

TWEAK is an activator of Hippo-YAP signaling protecting against hepatic Ischemia/ reperfusion injury

Hepatic ischemia–reperfusion injury (IRI) represents a formidable complication commonly linked with hemorrhagic shock, liver resection, and transplantation. This study aims to elucidate the role of Tumor Necrosis Factor-like Weak Inducer of Apoptosis (TWEAK) in the pathogenesis of hepatic I/R injury and to delineate the underlying mechanisms involved. Utilizing a hypoxia-reoxygenation model in human liver organoids (HLOs) alongside a murine model of warm ischemia–reperfusion injury, we systematically investigated the interplay between TWEAK, its receptor Fn14, and the HIPPO signaling pathway. Our findings indicate that TWEAK pretreatment significantly mitigates IRI in murine livers as well as hypoxia/reoxygenation injury in HLOs. Notably, administration of adeno-associated virus (AAV) to knock down Fn14 abrogated the protective effects of TWEAK in the murine model. Transcriptome sequencing analysis revealed that the interaction between TWEAK and Fn14 enhances cellular resistance to IRI by activating the HIPPO signaling pathway. Overall, TWEAK emerges as a promising therapeutic target for mitigating hepatic I/R injury, potentially improving outcomes in liver transplantation.

Activation of spleen tyrosine kinase (SYK) contributes to neuronal pyroptosis and cognitive impairment in diabetic mice via the NLRP3/Caspase-1/GSDMD signaling pathway.

Diabetes mellitus (DM) patients are at increased risk of cognitive impairment. The precise mechanisms underlying the association between DM and cognitive impairment remain unclear. Spleen tyrosine kinase (SYK), a crucial regulator of signal transduction, has been implicated in microglial pyroptosis in experimental ischemic stroke models. The present study investigated the potential role of SYK in DM-associated cognitive impairment. Diabetes was induced by streptozotocin (STZ) in C57BL/6 mice, and cognitive function and cerebral injury were assessed 12weeks later using the Morris water maze (MWM), TUNEL assay and Western blotting. In vitro, the inhibition of SYK was investigated in a mouse hippocampal neuronal cell line cultured with high glucose. Compared with control mice, DM mice presented impaired spatial learning and memory. Additionally, SYK activation was linked to neuronal pyroptosis, as evidenced by increases in the number of TUNEL-positive cells and protein levels of NLRP3, ASC, procaspase-1, caspase-1, GSDMD, the GSDMD N-terminal fragment, pro-IL-1β, and IL-1β in the hippocampus of DM mice. Compared with no treatment, SYK knockdown markedly attenuated cognitive impairment and histologic and ultrastructural pathological changes in the hippocampus of DM mice. The increased expression of pyroptosis-associated proteins and the increased number of TUNEL-positive cells were also significantly reduced. In vitro, high glucose significantly activated SYK to trigger the canonical pyroptotic pathway in cultured HT22 cells. The inhibition of SYK with a small interfering RNA or specific inhibitor significantly ameliorated the neuronal pyroptosis mediated by high glucose. Our findings demonstrate that SYK activation plays a pivotal role in promoting the cognitive impairment associated with DM. This effect is mediated by triggering neuronal pyroptosis through the canonical NLRP3/Caspase-1/GSDMD pathway. These results suggest that SYK may serve as a potential target for preventing or mitigating cognitive impairment in patients with DM.

Optimizing stent retrievers for mechanical enhancement and in vitro testing in acute ischemic stroke models

BackgroundAcute ischemic stroke (AIS) remains a major cause of morbidity and mortality worldwide. Mechanical thrombectomy, especially with stent retrievers, offers a promising treatment, particularly for patients ineligible for intravenous tissue plasminogen activator (IV tPA) therapy. This study aimed to develop and evaluate novel stent retriever designs to enhance mechanical properties and vessel compatibility.ResultsWe evaluated four stent designs using finite-element analysis (FEA) to assess their mechanical properties. Based on these evaluations, Stent D emerged as the optimal design due to its superior elasticity and adaptability. Comparative testing of Stent D against commercial stents, Solitaire FR and Trevo XP ProVue, revealed the following metrics: radial forces of 3.77 ± 0.01 N for Solitaire FR, 3.92 ± 0.08 N for Trevo XP ProVue, and 4.10 ± 0.07 N for Stent D; flexibility measurements of 0.38 ± 0.11 N for Solitaire FR, 0.91 ± 0.11 N for Trevo XP ProVue, and 0.59 ± 0.05 N for Stent D; deployment forces of 0.37 ± 0.02 N for Solitaire FR, 0.42 ± 0.04 N for Trevo XP ProVue, and 0.32 ± 0.02 N for Stent D; and recapture forces of 0.38 ± 0.01 N for Solitaire FR, 0.45 ± 0.02 N for Trevo XP ProVue, and 0.35 ± 0.01 N for Stent D. Thrombus retrieval rates were 96.16% for Solitaire FR and 95.51% for Stent D.ConclusionsThese findings demonstrate that Stent D performs comparably to commercial stents, highlighting its effective performance in AIS treatment. Stent D shows promise as a candidate for further clinical evaluation due to its superior mechanical properties and effective thrombus retrieval capabilities.

Berbamine Promotes the Repair of Lower Limb Muscle Damage in Chronic Limb-Threatening Ischemia by Inhibiting Local Inflammation and NF-κB Nuclear Translocation

Background/Objectives: Chronic Limb-Threatening Ischemia (CLTI) is a chronic limb ischemic disease caused by vascular lesions, characterized by pain, ulcers, and gangrene, which can be life-threatening in severe cases. The objective of this study is to explore whether Berbamine (BBM) can protect against and repair ischemic muscle tissue in the lower limbs; Methods: Using a mouse hindlimb ischemia (HLI) model, 36 C57BL6 mice were divided into sham, HLI, and HLI+BBM treatment groups. Results: Our findings indicate that BBM can restore motor function and muscle tissue pathology in mice, potentially by inhibiting the nuclear translocation of nuclear factor kappa-B (NF-κB), thereby alleviating tissue inflammation caused by chronic ischemia, reducing muscle cell apoptosis, inhibiting M1 macrophage polarization, and promoting angiogenesis. Conclusions: Our research suggests that BBM has the potential to protect against ischemic damage in lower limb muscle tissue, providing a new approach to the treatment of CLTI.

HUVECs-derived exosomes increase neovascularization and decrease limb necrosis in hindlimb ischemia

Chronic limb-threatening ischemia (CLTI) is the most severe manifestation of peripheral arterial disease (PAD) and imposes a significantly high burden due to its high risk of mortality and amputation. Revascularization is the first-line treatment for CLTI; however, the amputation rate remains high, and approximately one-third of patients are not eligible for this treatment. Therefore, there is an urgent need for more effective therapeutic strategies. The aim of this study was to investigate the effects and mechanisms of human umbilical vein endothelial cells (HUVECs)-derived exosomes on neovascularization and the degree of necrosis in a hindlimb ischemia model and to study the biological processes underlying their mechanisms. This is an in vivo experimental study with a post-test-only control group design. Forty BALB/c mice were randomized to receive injections of exosomes, conditioned media, and phosphate-buffered saline (PBS) one day after unilateral double ligation. A sham-operated group was also included as a control. Capillary density, arteriole lumen diameter, and histopathological necrosis were measured after seven days, while clinical necrosis was observed daily. MicroRNA profiling, in silico analysis, and transcriptomic analysis of vascular endothelial growth factor (VEGF) mRNA expression were performed to determine the possible biological processes. No amputation was found in the exosome group, as well as in the conditioned media and sham-operated groups, compared to three out of seven mice (43%) in the PBS group. The capillary density was higher in the exosome than in the PBS group (p=0.026). The arteriole lumen diameter in the exosome group was larger than in the PBS (p=0.033) and sham-operated (p=0.034) groups. The scores of clinical necrosis and histopathological necrosis in the exosome group were lower than the PBS group (p=0.005), while the histopathological necrosis scores were also lower but statistically insignificant. In silico analysis showed improvement in neovascularization and necrosis, possibly through energy regulation, PI3K/AKT and TGF-β activation, the ubiquitin-proteasome system, and tyrosine kinases receptors. HUVEC exosomes were associated with lower VEGF mRNA expression, which may indicate a more effective compensatory mechanism under ischemic conditions. The exosome group had the lowest VEGF mRNA expression compared to other groups, although the difference was not statistically significant. This study highlights that HUVECs-derived exosomes improve neovascularization and decrease necrosis in a hindlimb ischemia mice model, potentially by modulating several possible mechanisms.

Leukocyte as an adequate model for studying changes in energy metabolism in heart cells under the influence of cardiocytoprotectors in myocardial ischemia

The aim of this study was to determine the possibility of studying the nature of the influence of cardiocytoprotectors on energy metabolism in cardiomyocytes using a model of human peripheral blood leukocytes.Materials and methods. Sixty Wistar rats were divided into groups: 1) intact rats; 2) rats with experimental myocardial ischemia; 3) rats with myocardial ischemia, which were injected with cardiocytoprotector – trimetazidine, 4) meldonium, 5) cytoflavin and 6) ethoxydol. Animals were taken out of the experiment 10 days after the administration of drugs by decapitation. The activities of pyruvate dehydrogenase and citrate synthase were determined in mitochondria of myocardial homogenates and in mitochondria of leukocytes by spectrophotometric methods.Results. The decrease in pyruvate dehydrogenase and citrate synthase activity in cardiomyocytes and in leukocytes were revealed in case of myocardial ischemia modeling. The introduction of cardiocytoprotectors led to the activation of these enzymes both in heart cells and in blood leukocytes. Direct positive correlations were obtained between the activity of pyruvate dehydrogenase in the mitochondria of cardiomyocytes and in the mitochondria of leukocytes (r = 0.811; p &lt; 0.0001); between citrate synthase activity in the mitochondria of cardiomyocytes and in the mitochondria of leukocytes (r = 0.909; p &lt; 0.0001).Conclusion. Changes in energy metabolism in blood leukocytes under the influence of cytoprotectors reflect similar changes occurring in heart cells.

Angiotensin-II drives changes in microglia–vascular interactions in rats with heart failure

Activation of microglia, the resident immune cells of the central nervous system, leading to the subsequent release of pro-inflammatory cytokines, has been linked to cardiac remodeling, autonomic disbalance, and cognitive deficits in heart failure (HF). While previous studies emphasized the role of hippocampal Angiotensin II (AngII) signaling in HF-induced microglial activation, unanswered mechanistic questions persist. Evidence suggests significant interactions between microglia and local microvasculature, potentially affecting blood–brain barrier integrity and cerebral blood flow regulation. Still, whether the microglial-vascular interface is affected in the brain during HF remains unknown. Using a well-established ischemic HF rat model, we demonstrate the increased abundance of vessel-associated microglia (VAM) in HF rat hippocampi, along with an increased expression of AngII AT1a receptors. Acute AngII administration to sham rats induced microglia recruitment to brain capillaries, along with increased expression of TNFα. Conversely, administering an AT1aR blocker to HF rats prevented the recruitment of microglia to blood vessels, normalizing their levels to those in healthy rats. These results highlight the critical importance of a rather understudied phenomenon (i.e., microglia-vascular interactions in the brain) in the context of the pathophysiology of a highly prevalent cardiovascular disease, and unveil novel potential therapeutic avenues aimed at mitigating neuroinflammation in cardiovascular diseases.

The deleterious effects of CDK4/6 inhibition on renal recovery post-acute kidney injury

Acute kidney injury (AKI) is a common clinical problem, and patients who survive AKI have a high risk of chronic kidney disease (CKD). The acute protective effects of Cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors in AKI have been examined, there is still relatively little known regarding the impact of acute CDK4/6 inhibition on the chronic sequence of AKI. Therefore, we utilized the CDK4/6 inhibitor Palbociclib to examine the long-term effects of CDK4/6 inhibition in a rodent model of ischemic AKI. Palbociclib (Palb) was administered during the acute stage or post the acute stage of AKI and mice were sacrificed 21 days post injury. We found that Palb could cause renal senescence and renal fibrosis. Furthermore, dasatinib (D) plus quercetin (Q) were used to eliminate senescent cells in ischemic AKI murine model and Palb was administered post the treatment of D + Q. We found that Palb could reverse the senolytic and antifibrotic effects induced by D + Q, which indicates that the profibrotic effect of Palb could be ascribed to its pro-senescent effects. Our results demonstrate that CDK4/6 inhibitors treatment might be deleterious on the chronic sequence of AKI.

The role of therapeutic MicroRNA in arteriogenesis process in limb ischemia: A systematic review

Background Chronic limb-threatening ischemia (CLTI) is the most advanced stage of peripheral artery disease (PAD) and has poor clinical outcomes. Recently, stimulating arteriogenesis has been proposed to improve clinical outcomes. Several studies have shown that miRNAs have beneficial effects on limb ischemia related to arteriogenesis. This study aimed to review the roles of therapeutic miRNAs in the arteriogenesis of limb ischemia. Methods A systematic search was conducted through July 2021 using the PubMed, Scopus, and ScienceDirect databases. Two authors independently assessed studies that investigated the role of miRNAs in the arteriogenesis of limb ischemia, both in vivo and in clinical studies. Results All selected studies were in vivo studies, with a total of 36 articles and 28 types of miRNAs. miRNAs potentially regulate arteriogenesis by targeting different targets. The following miRNAs were upregulated to enhance arteriogenesis: miRNA-126-3p, -93, -675, -143-3p, -130a, -210, -146b, -21, -let-7g, -132/212, -150, and 155. Meanwhile, microRNAs needed to be downregulated, namely: miRNA-939-5p, -503, -199a-5p, -146a, -92a, -14q32 microRNA gene cluster, -15a/16, -100, -133a, -139-5p, -223, -352, -615-5p, -15b/5p, -124-3p, and 29a. MiRNA-126 was the most studied miRNA, and SPRED1 was the most common target of microRNA. However, the included studies showed high heterogeneity in terms of inducing hindlimb ischemia, the timing of administration, and the method used for evaluating arteriogenesis. Moreover, most studies presented unclear or high-risk bias. Conclusion MicroRNA application in a preclinical model of hindlimb ischemia has beneficial effects on arteriogenesis. This result indicates that miRNAs might be potentially beneficial in patients with CLTI. Registration The review protocol was registered with PROSPERO under registration number CRD42024484988.

Impaired oxytocin signalling in the central amygdala in rats with chronic heart failure.

Heart failure (HF) patients suffer from cognitive decline and mood impairments, but the molecular signals and brain circuits underlying these effects remain elusive. The hypothalamic neuropeptide oxytocin (OT) is critically involved in regulating mood, and OTergic signalling in the central amygdala (CeA) is a key mechanism that controls emotional responses including anxiety-like behaviours. Still, whether an altered OTergic signalling contributes to mood disorders in HF remains unknown. To address this, we used an ischaemic rat HF model, along with a highly multidisciplinary approach, to mechanistically study multiple levels of the hypothalamus-to-CeA OTergic circuit in male rats with HF. We aimed to test the hypothesis that sustained activation of the OT system following an infarct leads to depletion of OT content in this pathway, with subsequent changes in OT receptor expression and blunted modulation of local GABAergic circuits. We found that most of OTergic innervation of the CeA originated from the supraoptic nucleus (SON). While no differences in the numbers of SON→CeA OTergic neurons was observed between sham and HF rats, we observed a blunted content and release of OT from axonal terminals within the CeA. Moreover, we report downregulation of neuronal and astrocytic OT receptors, and impaired OTR-driven GABAergic synaptic activity within the CeA microcircuit of HF rats. We provide the first evidence that male HF rats display perturbations in the hypothalamus-to-amygdala OTergic circuit, laying the foundation for future translational studies targeting either the OT system or GABAergic amygdalar microcircuit to ameliorate mood impairments in rats or patients with chronic HF. KEY POINTS: Heart failure patients suffer from cognitive decline, depression and mood impairments, but the underlying mechanisms remain elusive. Acting within the central amygdala, the neuropeptide oxytocin regulates emotional responses, including anxiety-like behaviours. However, whether changes in oxytocin signalling occurs during heart failure is unknown. In this study, we used an ischaemic rat heart failure model to mechanistically study multiple levels of the hypothalamus-to-amygdala oxytocinergic circuit in this disease. We report an overall blunted oxytocinergic signalling pathway in rats with heart failure, including blunted content and release of oxytocin from axonal terminals, downregulation of neuronal and astrocytic oxytocin receptors, and impaired oxytocin-driven GABAergic synaptic activity within the central amygdala microcircuit of HF rats. These studies shed light on mechanisms that contribute to mood disorders in cardiovascular disease states and help to identify potential molecular targets for their improved treatment.

Abstract 4119062: A KLF2-BMPER-Smad1/5 checkpoint regulates high fluid shear stress-mediated artery remodeling

Background: Vascular remodeling to match arterial diameter to tissue metabolic requirements commonly fails in ischemic disease. Endothelial cell (EC) sensing of elevated fluid shear stress (FSS) from blood flow induces vessel outward remodeling to restore physiological FSS, but mechanisms are poorly understood. The Smad1/5 pathway, which is maximally activated at physiological FSS and suppressed at higher flow, opposes activation of Akt, suggesting that inhibiting Smad1/5 may be required for outward remodeling. Methods: In vitro flow studies used ECs in a parallel plate flow chamber. In vivo mouse studies used a carotid-jugular fistula model to induce high flow outward remodeling in the carotid artery, and femoral artery ligation to examine recovery from ischemia and arteriogenesis in the hindlimb. Results: Suppression of Smad1/5 at high FSS is mediated KLF2-dependent induction of the BMP pathway inhibitor BMPER, which suppresses Smad1/5 and de-inhibits Akt. In a mouse arteriovenous fistula (AVF) model, high FSS induces arterial outward remodeling coincident with elevated BMPER expression and Smad1/5 inactivation. Endothelial BMPER deletion impaired blood flow recovery and vascular remodeling in the AVF and a hindlimb ischemia (HLI) model, with the latter reversed by BMP9/10 blocking antibodies (bAbs). In both STZ-induced type 1 and HFD-induced type 2 diabetic mice that show poor recovery from HLI, BMP9/10 bAbs improved outcomes. Conclusions: Suppression of Smad1/5 through a KLF2-BMPER pathway is required for high FSS-mediated outward remodeling. Mimicking this pathway with BMP9/10 antibodies improves vascular remodeling in diabetic mice, suggesting a potential new therapeutic approach for ischemic disease.

Neuroprotective Effects of Ethanol Extract Polyscias guilfoylei (EEPG) Against Glutamate Induced Neurotoxicity in HT22 Cells.

Oxidative stress induced by glutamate is a significant contributor to neuronal cell damage and can lead to neurodegenerative diseases such as Alzheimer's, Huntington's, and ischemic brain injury. At the cellular level, oxidative stress increases Ca2+ ion influx and reactive oxygen species (ROS), which activate the MAPK signaling pathway. Additionally, the generation of ROS causes mitochondrial dysfunction, triggering apoptosis by promoting the translocation of AIF to the nucleus from the mitochondria. The neuroprotective potential of Polyscias guilfoylei has not yet been reported. Therefore, in this study, the ethanol extract of Polyscias guilfoylei (EEPG) was examined for its protective effect against oxidative cell damage caused by glutamate in neuronal cells. EEPG treatment increased the viability of HT22 cells exposed to high concentrations of glutamate. Cellular Ca2+ ion influx and ROS generation decreased with EEPG treatment in glutamate-treated HT22 cells. EEPG treatment inhibited MAPK activation and AIF nuclear translocation. In an in vivo study, EEPG attenuated brain cell death in an ischemic brain injury rat model. This study demonstrates the potential therapeutic effects of Polyscias guilfoylei in the treatment of ischemic brain injury.

Abstract 4129709: Aspirin-Nanoparticle for Dual Therapies: Targeted Anti-Inflammatory and Prolonged Anti-Platelet Effects for Atherosclerosis

Background: The current unmet needs for aspirin usage in atherosclerosis lie in its short half-life and narrow indication for anti-platelet effects. Daily aspirin intake is mandatory, and the anti-inflammatory effects of aspirin for atherosclerosis have not successfully translated to clinical practice. Nanoparticles remain in circulation for 2-3 days, with a large portion being cleared by splenic monocytes, which are known to inherently target inflamed sites. Hypothesis: By altering the pharmacokinetics of aspirin through loading into nanoparticles, aspirin-nanoparticles can exert prolonged anti-platelet effects and target atherosclerosis sites via monocyte carriers for anti-inflammatory effects, resulting in dual therapies. Methods: Splenic monocytes were loaded with aspirin-liposomes and co-cultured with endothelial cells or platelets to examine the interactions between them using high-resolution time-series microscopy. Prolonged anti-platelet effects and targeted anti-inflammatory effects of aspirin were validated in intact mice and hindlimb ischemia models, respectively. Furthermore, the dual therapies of aspirin-liposomes were validated in an atherosclerotic mouse model created by partial carotid ligation and a western diet in apoE gene knock-out mice. Results: When splenic monocytes were loaded with aspirin-liposomes, they emitted extracellular vesicles (EVs) loaded with aspirin towards endothelial cells or platelets. As inflamed cells upregulate caveolin expression, they uptake an increased amount of transferred EVs compared to non-inflamed cells. Additionally, aspirin-liposomes showed prolonged circulation time and increased splenic accumulation compared to aspirin itself, resulting in prolonged anti-platelet effects (&gt;7 days) and targeted anti-inflammatory effects at inflamed sites. Compared to the daily oral aspirin group in the atherosclerosis model, the weekly intravenous aspirin-liposome group showed superior therapeutic effects, including attenuated systemic and local inflammation and patent lumen in atherosclerotic sites. Conclusion: Aspirin-nanoparticles can exert prolonged anti-platelet effects combined with targeted anti-inflammatory effects, resulting in superior therapeutic effects on atherosclerosis.

Cardiotoxic and Cardioprotective Effects of Methylene Blue in the Animal Model of Cardiac Ischemia and Reperfusion.

Background/Objectives: Treatment of patients with myocardial ischemic diseases crucially involves cardiac reperfusion (CR). However, oxidative stress and tissue lesions caused by CR may also lead to lethal complications, such as arrythmias and vasoplegic syndrome (VS). Although methylene blue (MB) has long been used to treat VS due to cardiac ischemia and reperfusion (CIR) and/or surgery because of its vascular effects, MB's effects on the heart are unclear. Therefore, we investigated the potential cardioprotective or arrhythmogenic effects of MB in an animal model of CIR. To this end, 12-16-week-old male Wistar rats were divided into four experimental groups: (a) rats subjected to SHAM surgery with no ischemia; (b) rats subjected to CIR and treated with a vehicle (SS + CIR); and (c) rats subjected to CIR and treated with 2 mg/kg i.v. MB before ischemia (MB + ISQ) or (d) after ischemia but before reperfusion (ISQ + MB). An ECG analysis was used to evaluate the incidence of ventricular arrhythmias (VAs), atrioventricular blocks (AVBs), and lethality (LET) resulting from CIR. After CIR, rat hearts were removed for histopathological analysis and lipid hydroperoxide (LH) measurements. Results: The incidence of VA, AVB, and LET was significantly increased in the MB + ISQ group (VA = 100%; AVB = 100%; LET = 100%) but significantly reduced in the ISQ + MB group (VA = 42.8%; AVB = 28.5%; LET = 21.4%) compared with the SS + CIR group (VA = 85.7%; AVB = 71.4%; LET = 64.2%). LH concentration was significantly reduced in both MB-treated groups, but myocardial injuries were increased only in the MB + ISQ group when compared with the SS + CIR group. Conclusions: These results indicate that MB produces a biphasic effect on CIR, with cardiotoxic effects when administered before cardiac ischemia and cardioprotective effects when administered after ischemia but before cardiac reperfusion.