QiShen YiQi and its components attenuate acute thromboembolic stroke and carotid thrombosis by inhibition of CD62P/PSGL-1-mediated platelet-leukocyte aggregate formation

BACKGROUND

QiShen YiQi (QSYQ) dropping pill, a component-based Chinese medicine consisting of benefiting Qi (YQ) and activating blood (HX) components, has been reported to exert a beneficial effect on cerebral ischemia-induced stroke. However, its efficacy and pharmacological mechanism on acute thromboembolic stroke is not clear.

PURPOSE

This study is to explore the preventative effect and pharmacological mechanism of QSYQ and its YQ/HX components on the formation of platelet-leukocyte aggregation (PLA) in acute thromboembolic stroke.

STUDY DESIGN AND METHODS

In vivo thromboembolic stroke model and FeCl₃-induced carotid arterial occlusion models were used. Immunohistochemistry, Western blot, RT-qPCR, and flow cytometry experiments were performed to reveal the pharmacological mechanisms of QSYQ and its YQ/HX components.

RESULTS

In thromboembolic stroke rats, QSYQ significantly attenuated infarct area, improved neurological recovery, reduced PLA formation, and inhibited P-selection (CD62P)/ P-selectin glycoprotein ligand-1 (PSGL-1) expressions. The YQ component preferentially down-regulated PSGL-1 expression in leukocyte, while the HX component preferentially down-regulated CD62P expression in platelet. In carotid arterial thrombosis mice, QSYQ and its YQ/HX components inhibited thrombus formation, prolonged vessel occlusion time, reduced circulating leukocytes and P-selectin expression. PLA formation and platelet/leukocyte adhesion to endothelial cell were also inhibited by QSYQ and its YQ/HX components in vitro.

CONCLUSION

QSYQ and YQ/HX components attenuated thromboembolic stroke and carotid thrombosis by decreasing PLA formation via inhibiting CD62P/PSGL-1 expressions. This study shed a new light on the prevention of thromboembolic stroke.

Remote ischemic conditioning attenuates blood-brain barrier disruption after recombinant tissue plasminogen activator treatment via reducing PDGF-CC

Treatment of acute ischemic stroke with the recombinant tissue plasminogen activator (rtPA) is associated with increased blood-brain barrier (BBB) disruption and hemorrhagic transformation. Remote ischemic conditioning (RIC) has demonstrated neuroprotective effects against acute ischemic stroke. However, whether and how RIC regulates rtPA-associated BBB disruption remains unclear. Here, a rodent model of thromboembolic stroke followed by rtPA thrombolysis at different time points was performed with or without RIC. Brain infarction, neurological outcomes, BBB permeability, and intracerebral hemorrhage were assessed. The platelet-derived growth factor CC (PDGF-CC)/PDGFRα pathway in the brain tissue, PDGF-CC levels in the skeletal muscle and peripheral blood were also measured. Furthermore, impact of RIC on serum PDGF-CC levels were measured in healthy subjects and AIS patients. Our results showed that RIC substantially reduced BBB injury, intracerebral hemorrhage, cerebral infarction, and neurological deficits after stroke, even when rtPA was administrated in a delayed therapeutic time window. Mechanistically, RIC significantly decreased PDGFRα activation in ischemic brain tissue and reduced blood PDGF-CC levels, which partially resulted from PDGF-CC reduction in the skeletal muscle of RIC-applied hindlimbs and platelets. Intravenous or intraventricular recombinant PDGF-CC supplementation abolished RIC protective effects on BBB integrity. Moreover, similar changes of PDGF-CC in serum by RIC were also observed in healthy humans and acute ischemic stroke patients. Together, our study demonstrates that RIC can attenuate rtPA-aggravated BBB disruption after ischemic stroke via reducing the PDGF-CC/PDGFRα pathway and thus supports RIC as a potential approach for BBB disruption prevention or treatment following thrombolysis.

An In Vivo Mouse Model to Study Blood-Brain Barrier Destabilization in the Chronic Phase of Stroke

Cerebral ischemic injury evokes a complex cascade of pathophysiological events at the blood-vascular-parenchymal interface. These evolve over time and space and result in progressive neurological damage. Emerging evidence suggests that blood-brain barrier (BBB) recovery and reestablishment of BBB impermeability are incomplete and that these could influence stroke injury recovery, increase the risk of new stroke occurrence, and be a solid substrate for developing vascular dementia. Recent work from the author's laboratory has established the existence of incomplete BBB recovery in chronic stroke conditions that was induced by structural alterations to brain endothelial junctional complexes and persistent BBB leakage. The experimental methodology presented here is focused on modelling chronic stroke injury using an in vivo thromboembolic mouse stroke model and how to evaluate the kinetics and magnitude of BBB hyperpermeability in chronic stroke conditions using a combination of magnetic resonance imaging, tracer studies, and immunohistochemistry.

Benefit and harm of anticoagulation in the prevention of thromboembolic stroke for non- valvular atrial fibrillation in haemodialysis patients - a Top End of Northern Australia study

BACKGROUND

Warfarin for the prevention of non-valvular atrial fibrillation related thromboembolic stroke in patients on maintenance haemodialysis is controversial. Despite the exclusion of haemodialysis patients in randomised control trials, the American Heart Association/American College of Cardiology has recommended warfarin in high-risk AF patients.

AIM

We retrospectively examined the utility of warfarin anticoagulation therapy in our prevalent haemodialysis patients over 10 years of follow-up.

METHODS

Eligible patients were retrospectively identified and stratified to two cohorts based on whether warfarin was prescribed. The outcomes of interest were ischaemic stroke, haemorrhagic stroke and death from any cause. Rate ratio and cox proportional hazard regression model were compare the differences in outcome between the two cohorts. The Kaplan-Meier method was used to analyse survival.

RESULTS

Three ischaemic strokes and four haemorrhagic strokes occurred in the unexposed group of 166 patients over 484.44 patient-years follow-up. One ischaemic stroke and no cases of haemorrhagic stroke occurred in the exposed warfarin group of 16 patients over 39.32 patient-years of follow-up. 87% of patients in both groups were indigenous. More than 90% of each cohort was had CHA2DS2VaSc score ≥2. 101 deaths occurred in the follow-up period, ninety in the unexposed group and eleven in the warfarin group. A non-statistically significant trend towards increasing mortality was observed in the warfarin group (Hazard ratio =1.63, p=0.13).

CONCLUSION

This retrospective study of prevalent haemodialysis patients with co-existing history of non-valvular AF failed to demonstrate sufficient evidence for the routine use of warfarin for prophylaxis of thromboembolic stroke. This article is protected by copyright. All rights reserved.

Pseudoginsenoside-F11 ameliorates thromboembolic stroke injury in rats by reducing thromboinflammation

Pseudoginsenoside-F11 (PF11), an ocotillol-type ginsenoside, has been reported to exert neuroprotective effects on ischemic stroke induced by permanent and transient middle cerebral artery occlusion in experimental animals. The aim of the present study was to investigate the effect of PF11 on thromboembolic stroke in rats and its possible mechanisms on thromboinflammation. PF11 (4, 12, 36 mg/kg) was injected intravenously (i.v.) once a day for 3 consecutive days to male Wistar rats followed by embolic middle cerebral artery occlusion (eMCAO). The results showed that PF11 significantly reduced the cerebral infarction volume, brain edema and neurological deficits induced by eMCAO. Meanwhile, the thromboinflammation in the ischemic hemisphere was observed at 24 h after eMCAO, as indicated by the increased number of microvascular thrombus and inflammatory response. Moreover, eMCAO resulted in the up-regulation of platelet glycoprotein Ibα (GPIbα) and VI (GPVI), as well as the activation of contact-kinin pathway. Notably, PF11 significantly reversed all these changes. Furthermore, PF11 prevented the eMCAO-induced loss of tight junction proteins and up-regulation of matrix metalloproteinase-9 (MMP-9), thus leading to the alleviation of blood-brain barrier (BBB) damage. In conclusion, the present study revealed that thromboinflammation was induced in the ischemic hemisphere of rats after eMCAO and PF11 exerted marked protective effects against thromboembolic stroke by attenuating thromboinflammation and preventing BBB damage. This research further identifies the potential therapeutic role of PF11 for ischemic stroke.

The combination of coronary sinus ostial atresia/abnormalities and a small persistent left superior vena cava-Opportunity for left ventricular lead implantation and unrecognized source of thromboembolic stroke

BACKGROUND

Coronary sinus (CS) ostial atresia/abnormalities prevent access to the CS from the right atrium (RA) for left ventricular (LV) lead implantation. Some patients with CS ostial abnormalities also have a small persistent left superior vena cava (sPLSVC).

OBJECTIVE

The purpose of this study was to describe CS ostial abnormalities and sPLSVC as an opportunity for LV lead implantation and unrecognized source of stroke.

METHODS

Twenty patients with CS ostial abnormalities and sPLSVC were identified. Clinical information, imaging methods, LV lead implantation techniques, and complications were summarized.

RESULTS

Forty percent had at least 1 previously unsuccessful LV lead placement. In 70%, sPLSVC was identified by catheter manipulation and contrast injection in the left brachiocephalic vein, and in 30% by levophase CS venography. In 30%, sPLSVC was associated with drainage from the CS into the left atrium (LA). When associated with CS ostial abnormalities, the sPLSVC diameter averaged 5.6 ± 3 mm. sPLSVC was used for successful LV lead implantation in 90% of cases. In 80%, the LV lead was implanted down sPLSVC, and in 20%, sPLSVC was used to access the CS from the RA. Presumably because of unrecognized drainage from the CS to the LA, 1 patient had a stroke during implantation via sPLSVC.

CONCLUSION

When CS ostial abnormalities prevent access to the CS from the RA, sPLSVC can be used to successfully implant LV leads. In some, the CS partially drains into the LA and stroke can occur spontaneously or during lead intervention. It is important to distinguish sPLSVC associated with CS ostial abnormalities from isolated PLSVC.

Thromboembolic Model of Cerebral Ischemia and Reperfusion in Mice

Ischemic stroke is the fourth leading cause of death in the USA and a prominent cause of death globally. Besides thrombolytic therapy used in a small subset of patients, no alternative therapeutic strategy has been shown to improve the outcome of stroke patients. Preclinical models of ischemic stroke are an essential tool for investigating pathogenic processes that happen after the ischemic insult, as well as to screen for candidate therapeutic interventions. There are several models of rodent ischemic stroke including mechanical occlusion, thromboembolic stroke, and photothrombotic stroke. However, models that permit studying stroke in the context of thrombolytic therapy, such as thromboembolic models, are becoming of increasing interest to the research community. In this chapter, we describe a thromboembolic model of ischemic stroke with and without tissue-plasminogen activator-induced reperfusion. We describe protocols for microemboli preparation, surgical procedure, and post-stroke assessment of animals.

Human Neural Stem Cell Extracellular Vesicles Improve Tissue and Functional Recovery in the Murine Thromboembolic Stroke Model

Over 700 drugs have failed in stroke clinical trials, an unprecedented rate thought to be attributed in part to limited and isolated testing often solely in “young” rodent models and focusing on a single secondary injury mechanism. Here, extracellular vesicles (EVs), nanometer-sized cell signaling particles, were tested in a mouse thromboembolic (TE) stroke model. Neural stem cell (NSC) and mesenchymal stem cell (MSC) EVs derived from the same pluripotent stem cell (PSC) line were evaluated for changes in infarct volume as well as sensorimotor function. NSC EVs improved cellular, tissue, and functional outcomes in middle-aged rodents, whereas MSC EVs were less effective. Acute differences in lesion volume following NSC EV treatment were corroborated by MRI in 18-month-old aged rodents. NSC EV treatment has a positive effect on motor function in the aged rodent as indicated by beam walk, instances of foot faults, and strength evaluated by hanging wire test. Increased time with a novel object also indicated that NSC EVs improved episodic memory formation in the rodent. The therapeutic effect of NSC EVs appears to be mediated by altering the systemic immune response. These data strongly support further preclinical development of a NSC EV-based stroke therapy and warrant their testing in combination with FDA-approved stroke therapies.

Effect of human recombinant prourokinase(rhpro-UK) on thromboembolic stroke in rats

We evaluated the efficacy and safety of human recombinant prourokinase ( rhpro-UK) on thromboembolic stroke in rats. 60 rats with thromboembolic stroke were divided into 6 groups (n = 10). The model group was given saline, the reagent groups were given rhpro-UK (5, 10, 20 × 10⁴U/kg), and positive control groups were given urokinase (UK) 10 × 10⁴U/kg and recombinant tissue plasminogen activator (rt-PA) 9mg/kg through intravenous infusion at 1.5h after embolism. And other 10 rats without occluded by autologous blood clots as the sham group were given saline. At 6h after treatment, neurological deficit score and Magnetic Resonance Imaging(MRI) including T₁WI and T₂WI sequence scanning were measured. At 24h after treatment, the brain was cut for 2,3,5-triphenyltetrazolium chloride (TTC) staining and aspectrophotometric assay to measure the infarct area and intracerebral hemorrhage after neurological deficit detection. rhpro-UK (5, 10, 20 × 10⁴ U/kg) improved neurological disorder by 39.1 ± 19.7% (n = 10, P > 0.05), 65.2 ± 14.2% (n = 10, P < 0.01) and 65.2 ± 14.2% (n = 10, P < 0.01) maximally; decreased brain lesion volume by 36.7 ± 34.8% (n = 10, P < 0.05), 77.6 ± 7.7% (n = 10, P < 0.01) and 80.5 ± 6.9% (n = 10, P < 0.01); decreased infarction area by 38.2 ± 24.0% (n = 10, P < 0.01), 73.9 ± 5.2% (n = 10, P < 0.001) and 79.7 ± 4.0% (n = 10, P < 0.001) respectively, and there were no statistics difference between rhpro-UK (5, 10, 20 × 10⁴ U/kg) and each positive groups at intracerebral hemorrhage (P > 0.05). Rhpro-UK improved the damaged neural function, decreased the extent of the disease and did not raise bleeding, had protective effects for cerebral ischemia in rats.

Improved persistence with non-vitamin-K oral anticoagulants compared with warfarin in patients with atrial fibrillation: recent Australian experience

OBJECTIVE

Long-term anticoagulant therapy in patients with non-valvular atrial fibrillation (AF) is essential to prevent thromboembolic complications, especially ischemic stroke, but treatment persistence with warfarin is poor. This study examines Australian nationwide persistence in AF patients using a non-vitamin-K oral anticoagulant (NOAC) drug.

RESEARCH DESIGN AND METHODS

We assessed national Pharmaceutical Benefit Scheme records November-December 2013 through March 2015 for prescription of NOAC drugs in a 10% random sample of long-term concession card holders. An historical comparison was made with patients prescribed warfarin in 2008. Key outcome measures were (i) the proportion not filling first repeat prescription and (ii) discontinuation within 12 months.

RESULTS

A total of 1471 patients with AF were new users of a NOAC drug (228 apixaban, 645 dabigatran, 598 rivaroxaban) and 1348 were new users of warfarin. Mean age on a NOAC was 76 years (58% male), on warfarin 74 years (54% male). Only 9% (95% CI 7-10) failed to collect the first repeat prescription on a NOAC, 30% (27-32) discontinued within 12 months; corresponding proportions on warfarin were 14% (12-16) and 62% (60-65). In a regression model adjusted for age, gender, heart failure, hypertension and diabetes, warfarin-treated patients were 2.5 times more likely to discontinue over 12 months than those who were NOAC treated (hazard ratio =2.47 [95% CI 2.19-2.79]).

CONCLUSIONS

Persistence with NOAC drugs in patients with AF appears to be superior to warfarin. If continued long-term, this alone will be of clinical importance in the prevention of stroke and death.

Partial MHC Constructs Treat Thromboembolic Ischemic Stroke Characterized by Early Immune Expansion

Inflammation and thrombosis are tightly linked, with inflammation contributing to thromboembolism and to stroke outcome. Thromboembolism is a frequent cause of ischemic stroke; yet, the most used occlusion mouse models of experimental stroke do not effectively replicate thromboembolism. Our group recently described a novel thromboembolic mouse model of stroke that successfully occludes the middle cerebral artery with high reproducibility. In the current study, we characterize the peripheral and local immune outcomes as well as the ischemic response to immune therapy in a clinically relevant mouse model of thromboembolic stroke. Brain and spleen tissues were harvested 24 h after thromboembolic stroke and cells immunophenotyped by flow cytometry. We observed a significant increase in neutrophils and early activated T cells in the spleen and an increase in neutrophils and activated monocytes/microglia in the ischemic cortex after thromboembolic stroke. Moreover, as was shown previously for transient MCAO models, treatment of thromboembolic stroke with partial MHC constructs significantly reduced ischemic damage indicating an equivalent effect of this immune-based therapy in the thromboembolic model that better mimics the pathophysiology of human stroke.

A 2 × 2 factorial design for the combination therapy of minocycline and remote ischemic perconditioning: efficacy in a preclinical trial in murine thromboembolic stroke model

Background

After the failure of so many drugs and therapies for acute ischemic stroke, innovative approaches are needed to develop new treatments. One promising strategy is to test combinations of agents in the pre-hospital setting prior to the administration of intravenous tissue plasminogen activator (IV-tPA) and/ or the use of mechanical reperfusion devices in the hospital.

Methods

We performed a 2 × 2 factorial design preclinical trial where we tested minocycline (MINO), remote ischemic perconditioning (RIPerC) and their combination treatment in a thromboembolic clot model of stroke in mice, without IV-tPA or later treated with IV-tPA at 4 hours post-stroke. Cerebral blood flow (CBF) was measured by laser speckle contrast imaging (LSCI), behavioral outcomes as neurological deficit score (NDS) and adhesive tape removal test, and infarct size measurement were performed at 48 hours post-stroke. Mice within the experimental sets were randomized for the different treatments, and all outcome measures were blinded.

Results

RIPerC significantly improved CBF as measured by LSCI in both with and without tPA treated mice (P < 0.001). MINO and RIPerC treatment were effective alone at reducing infarct size (p < 0.0001) and improving short-term functional outcomes (p < 0.001) in the tPA and non-tPA treated animals. The combination treatment of MINO and RIPerC significantly reduced the infarct size greater than either intervention alone (p < 0.05). There were trends in favor of improving functional outcomes after combination treatment of MINO and RIPerC; however combination treatment group was not significantly different than the individual treatments of MINO and RIPerC. There was no “statistical” interaction between minocycline and RIPerC treatments indicating that the effects of RIPerC and MINO were additive and not synergistic on the outcome measures.

Conclusion

In the future, combining these two safe and low cost interventions in the ambulance has the potential to “freeze” the penumbra and improve outcomes in stroke patients. This pre-clinical 2 × 2 design can be easily translated into a pre-hospital clinical trial.

Initial experience with post Lariat left atrial appendage leak closure with Amplatzer septal occluder device and repeat Lariat application

BACKGROUND

Left atrial appendage (LAA) ligation with the Lariat device is a therapeutic option to prevent thromboembolic stoke in patients with nonvalvular atrial fibrillation (AF) at high risk for systemic thromboembolization and bleeding related to use of anticoagulation. In rare cases, this procedure could leave the LAA incompletely ligated with continued risk of stroke.

OBJECTIVE

The purpose of this study was to investigate the incidence and characteristics of LAA leak following ligation using the Lariat device and the feasibility of leak closure with the Amplatzer septal occluder device or a repeat Lariat application.

METHODS

Seventy-one consecutive patients who underwent LAA ligation by the Lariat device were followed-up with transesophageal echocardiography to evaluate for the presence of appendage leaks, characterization of the leaks, and the presence of any thrombus. Patients with LAA leaks underwent definite closure of the leak.

RESULTS

Six patients had LAA leaks with a mean leak size of 4.3 ± 0.6 mm. All leaks were concentric in nature. None of the patients had LAA thrombus. Leaks in 5 of these patients were successfully closed using an Amplatzer septal occluder device (St. Jude Medical); the leak in the sixth patient was closed using a repeat Lariat procedure.

CONCLUSION

LAA leaks from incomplete ligation of the LAA following the Lariat procedure are not uncommon and could be successfully closed with an Amplatzer septal occluder device or a repeat Lariat procedure.