Safety of thrombolysis in acute ischemic stroke: a review of complications, risk factors, and newer technologies

Tenecteplase-associated orolingual angioedema: A case report and literature review

PURPOSE

Orolingual angioedema (OA) secondary to administration of thrombolytic therapy is a rare, but serious, known adverse effect. Despite the lack of robust evidence for their use, C1 esterase inhibitors are recommended by guidelines for the treatment of refractory thrombolytic-associated OA. This report highlights the use of a C1 esterase inhibitor in a patient with tenecteplase-associated OA unresolved by antihistamine and corticosteroid therapy.

SUMMARY

A 67-year-old white male with a history of hypertension managed with lisinopril presented to the emergency department with acute onset of slurred speech and left-sided hemiparesis. Following workup, an outside hospital's neurology stroke team suspected an acute infarct and determined the patient to be a candidate for tenecteplase. Approximately 1 hour after tenecteplase administration, the patient began complaining of dyspnea and mild oral angioedema. Immediate interventions for OA management included intravenous therapy with dexamethasone 10 mg, diphenhydramine 25 mg, and famotidine 20 mg. After an additional 30 minutes, the patient's OA symptoms continued to progress and a C1 esterase inhibitor (Berinert) was administered. Shortly after administration of the C1 esterase inhibitor, the patient's symptoms continued to worsen, ultimately leading to endotracheal intubation. Following intubation, symptom improvement was noted, and the patient was safely extubated after 30 hours.

CONCLUSION

Although rare, OA is a potentially life-threatening complication of tenecteplase therapy and requires prompt pharmacological intervention to optimize patient outcomes. Currently, no single agent or treatment algorithm exists that has shown significant efficacy or safety in the setting of thrombolytic-associated OA. Until data are available for C1 esterase inhibitors in this application, these inhibitors should only be considered if there is continued symptom progression after intravenous administration of corticosteroids and antihistamines.

LOX-1 and MMP-9 Inhibition Attenuates the Detrimental Effects of Delayed rt-PA Therapy and Improves Outcomes After Acute Ischemic Stroke

BACKGROUND

Acute ischemic stroke triggers endothelial activation that disrupts vascular integrity and increases hemorrhagic transformation leading to worsened stroke outcomes. rt-PA (recombinant tissue-type plasminogen activator) is an effective treatment; however, its use is limited due to a restricted time window and hemorrhagic transformation risk, which in part may involve activation of MMPs (matrix metalloproteinases) mediated through LOX-1 (lectin-like oxLDL [oxidized low-density lipoprotein] receptor 1). This study's overall aim was to evaluate the therapeutic potential of novel MMP-9 (matrix metalloproteinase 9) ± LOX-1 inhibitors in combination with rt-PA to improve stroke outcomes.

METHODS

A rat thromboembolic stroke model was utilized to investigate the impact of rt-PA delivered 4 hours poststroke onset as well as selective MMP-9 (JNJ0966) ±LOX-1 (BI-0115) inhibitors given before rt-PA administration. Infarct size, perfusion, and hemorrhagic transformation were evaluated by 9.4-T magnetic resonance imaging, vascular and parenchymal MMP-9 activity via zymography, and neurological function was assessed using sensorimotor function testing. Human brain microvascular endothelial cells were exposed to hypoxia plus glucose deprivation/reperfusion (hypoxia plus glucose deprivation 3 hours/R 24 hours) and treated with ±tPA and ±MMP-9 ±LOX-1 inhibitors. Barrier function was assessed via transendothelial electrical resistance, MMP-9 activity was determined with zymography, and LOX-1 and barrier gene expression/levels were measured using qRT-PCR (quantitative reverse transcription PCR) and Western blot.

RESULTS

Stroke and subsequent rt-PA treatment increased edema, hemorrhage, MMP-9 activity, LOX-1 expression, and worsened neurological outcomes. LOX-1 inhibition improved neurological function, reduced edema, and improved endothelial barrier integrity. Elevated MMP-9 activity correlated with increased edema, infarct volume, and decreased neurological function. MMP-9 inhibition reduced MMP-9 activity and LOX-1 expression. In human brain microvascular endothelial cells, LOX-1/MMP-9 inhibition differentially attenuated MMP-9 levels, inflammation, and activation following hypoxia plus glucose deprivation/R.

CONCLUSIONS

Our findings indicate that LOX-1 inhibition and ± MMP-9 inhibition attenuate negative aspects of ischemic stroke with rt-PA therapy, thus resulting in improved neurological function. While no synergistic effect was observed with simultaneous LOX-1 and MMP-9 inhibition, a distinct interaction is evident.

Thrombus Imaging Characteristics to Predict Early Recanalization in Anterior Circulation Large Vessel Occlusion Stroke

The early management of transferred patients with a large vessel occlusion (LVO) stroke could be improved by identifying patients who are likely to recanalize early. We aim to predict early recanalization based on patient clinical and thrombus imaging characteristics. We included 81 transferred anterior-circulation LVO patients with an early recanalization, defined as the resolution of the LVO or the migration to a distal location not reachable with endovascular treatment upon repeated radiological imaging. We compared their clinical and imaging characteristics with all (322) transferred patients with a persistent LVO in the MR CLEAN Registry. We measured distance from carotid terminus to thrombus (DT), thrombus length, density, and perviousness on baseline CT images. We built logistic regression models to predict early recanalization. We validated the predictive ability by computing the median area-under-the-curve (AUC) of the receiver operating characteristics curve for 100 5-fold cross-validations. The administration of intravenous thrombolysis (IVT), longer transfer times, more distal occlusions, and shorter, pervious, less dense thrombi were characteristic of early recanalization. After backward elimination, IVT administration, DT and thrombus density remained in the multivariable model, with an AUC of 0.77 (IQR 0.72-0.83). Baseline thrombus imaging characteristics are valuable in predicting early recanalization and can potentially be used to optimize repeated imaging workflow.

Magnetically powered microwheel thrombolysis of occlusive thrombi in zebrafish

Tissue plasminogen activator (tPA) is the only FDA-approved treatment for ischemic stroke but carries significant risks, including major hemorrhage. Additional options are needed, especially in small vessel thrombi which account for ~25% of ischemic strokes. We have previously shown that tPA-functionalized colloidal microparticles can be assembled into microwheels (µwheels) and manipulated under the control of applied magnetic fields to enable rapid thrombolysis of fibrin gels in microfluidic models of thrombosis. Transparent zebrafish larvae have a highly conserved coagulation cascade that enables studies of hemostasis and thrombosis in the context of intact vasculature, clotting factors, and blood cells. Here, we show that tPA-functionalized µwheels can perform rapid and targeted recanalization in vivo. This effect requires both tPA and µwheels, as minimal to no recanalization is achieved with tPA alone, µwheels alone, or tPA-functionalized microparticles in the absence of a magnetic field. We evaluated tPA-functionalized µwheels in CRISPR-generated plasminogen (plg) heterozygous and homozygous mutants and confirmed that tPA-functionalized µwheels are dose-dependent on plasminogen for lysis. We have found that magnetically powered µwheels as a targeted tPA delivery system are dramatically more efficient at plasmin-mediated thrombolysis than systemic delivery in vivo. Further development of this system in fish and mammalian models could enable a less invasive strategy for alleviating ischemia that is safer than directed thrombectomy or systemic infusion of tPA.

Association between fibrinogen-to-albumin ratio and functional prognosis of 3 months in patients with acute ischemic stroke after intravenous thrombolysis

BACKGROUND

The presence of high fibrinogen and low albumin levels in serum is associated with a negative prognosis in acute ischemic stroke (AIS). Fibrinogen-to-albumin ratio (FAR), a new inflammatory biomarker, may provide better prognostic insights in patients with AIS than separate evaluation of fibrinogen or albumin. The objective of this investigation is to examine the correlation between FAR and 3-month functional prognosis after intravenous thrombolysis (IVT) in AIS patients.

METHODS

The retrospective study recruited AIS patients who received IVT from June 2014 to December 2021. The 3-month functional prognosis was assessed using the Modified Rankin Scale (mRS). A mRS score of ≤2 indicated a good outcome, whereas a mRS score of >2 suggested a poor outcome.

RESULTS

A total of 591 AIS patients who underwent IVT were included and 147 patients (24.9 %) had a poor outcome. Among the 102 pairs of patients after propensity score matching, there was a significant association between FAR and 3-month prognosis (adjusted OR, 1.19; 95% CI, 1.03-1.38; p = .020). The optimal FAR cutoff value was found to be 7.57, and even after stratifying patients based on this value, we still observed a significant correlation between high FAR level and poor outcome (adjusted OR, 2.08; 95% CI, 1.28-3.40; p = .003).

CONCLUSIONS

FAR may serve as a prospective biomarker of predicting 3-month prognosis in AIS patients after IVT.

Risk Factors Associated With Exclusion of Obese Patients Ischemic Stroke With a History of Smoking From Thrombolysis Therapy

The objective of this study is to determine risk factors that may contribute to exclusion decision from recombinant tissue plasminogen activator (rtPA) in patients with acute ischemic stroke (AIS) with a combined current or history of smoking and obesity. This study was conducted on data from 5469 patients with AIS collected from a regional stroke registry. Risk factors associated with inclusion or exclusion from rtPA were determined using multivariate logistic regression analysis. The adjusted odds ratios and 95% confidence interval for each risk factor were used to predict the increasing odds of an association of a specific risk factor with exclusion from rtPA. In the adjusted analysis, obese patients with AIS with a history of smoking (current and previous) excluded from rtPA were more likely to present with carotid artery stenosis (OR = 0.069, 95% CI 0.011-0.442), diabetes (OR = 0.604, 95% CI 0.366-0.997), higher total cholesterol (OR = 0.975, 95% CI 0.956-0.995), and history of alcohol use (OR = 0.438, 95% CI 0.232-0.828). Higher NIHSS score (OR = 1.051, 95% CI 1.017-1.086), higher triglycerides (OR = 1.004, 95% CI 1.001-1.006), and higher high-density lipoprotein (OR = 1.028, 95% CI 1.000-1.057) were associated with the inclusion for rtPA. Our findings reveal specific risk factors that contribute to the exclusion of patients with AIS with a combined effect of smoking and obesity from rtPA. These findings suggest the need to develop management strategies to improve the use of rtPA for obese patients with AIS with a history of smoking.

Magnetically Powered Microwheel Thrombolysis of Occlusive Thrombi in Zebrafish

Tissue plasminogen activator (tPA) is the only FDA approved treatment for ischemic stroke but carries significant risks, including major hemorrhage. Additional options are needed, especially in small vessel thrombi which account for ~25% of ischemic strokes. We have previously shown that tPA-functionalized colloidal microparticles can be assembled into microwheels (µwheels) and manipulated under the control of applied magnetic fields to enable rapid thrombolysis of fibrin gels in microfluidic models of thrombosis. Providing a living microfluidic analog, transparent zebrafish larvae have a highly conserved coagulation cascade that enables studies of hemostasis and thrombosis in the context of intact vasculature, clotting factors, and blood cells. Here we show that tPA-functionalized µwheels can perform rapid and targeted recanalization in vivo. This effect requires both tPA and µwheels, as minimal to no recanalization is achieved with tPA alone, µwheels alone, or tPA-functionalized microparticles in the absence of a magnetic field. We evaluated tPA-µwheels in CRISPR-generated plasminogen (plg) heterozygous and homozygous mutants and confirmed that tPA-µwheels are dose-dependent on plasminogen for lysis. We have found that magnetically powered µwheels as a targeted tPA delivery system are dramatically more efficient at plasmin-mediated thrombolysis than systemic delivery in vivo. Further development of this system in fish and mammalian models could enable a less invasive strategy for alleviating ischemia that is safer than directed thrombectomy or systemic infusion of tPA.

Dual role of Vascular Endothelial Growth Factor-C (VEGF-C) in post-stroke recovery

Using a mouse model of ischemic stroke, this study characterizes stroke-induced lymphangiogenesis at the cribriform plate (CP). While blocking CP lymphangiogenesis with a VEGFR-3 inhibitor improves stroke outcome, administration of VEGF-C induced larger brain infarcts.

Abstract

Cerebrospinal fluid (CSF), antigens, and antigen-presenting cells drain from the central nervous system (CNS) into lymphatic vessels near the cribriform plate and dural meningeal lymphatics. However, the pathological roles of these lymphatic vessels surrounding the CNS during stroke are not well understood. Using a mouse model of ischemic stroke, transient middle cerebral artery occlusion (tMCAO), we show that stroke induces lymphangiogenesis near the cribriform plate. Interestingly, lymphangiogenesis is restricted to lymphatic vessels at the cribriform plate and downstream cervical lymph nodes, without affecting the conserved network of lymphatic vessels in the dura. Cribriform plate lymphangiogenesis peaks at day 7 and regresses by day 14 following tMCAO and is regulated by VEGF-C/VEGFR-3. These newly developed lymphangiogenic vessels transport CSF and immune cells to the cervical lymph nodes. Inhibition of VEGF-C/VEGFR-3 signaling using a blocker of VEGFR-3 prevented lymphangiogenesis and led to improved stroke outcomes at earlier time points but had no effects at later time points following stroke. Administration of VEGF-C after tMCAO did not further increase post-stroke lymphangiogenesis, but instead induced larger brain infarcts. The differential roles for VEGFR-3 inhibition and VEGF-C in regulating stroke pathology call into question recent suggestions to use VEGF-C therapeutically for stroke.

Miniaturized Stacked Transducer for Intravascular Sonothrombolysis With Internal-Illumination Photoacoustic Imaging Guidance and Clot Characterization

Thromboembolism in blood vessels can lead to stroke or heart attack and even sudden death unless brought under control. Sonothrombolysis enhanced by ultrasound contrast agents has shown promising outcome on effective treatment of thromboembolism. Intravascular sonothrombolysis was also reported recently with a potential for effective and safe treatment of deep thrombosis. Despite the promising treatment results, the treatment efficiency for clinical application may not be optimized due to the lack of imaging guidance and clot characterization during the thrombolysis procedure. In this paper, a miniaturized transducer was designed to have an 8-layer PZT-5A stacked with an aperture size of 1.4 × 1.4 mm2 and assembled in a customized two-lumen 10-Fr catheter for intravascular sonothrombolysis. The treatment process was monitored with internal-illumination photoacoustic tomography (II-PAT), a hybrid imaging modality that combines the rich contrast of optical absorption and the deep penetration of ultrasound detection. With intravascular light delivery using a thin optical fiber integrated with the intravascular catheter, II-PAT overcomes the penetration depth limited by strong optical attenuation of tissue. In-vitro PAT-guided sonothrombolysis experiments were carried out with synthetic blood clots embedded in tissue phantom. Clot position, shape, stiffness, and oxygenation level can be estimated by II-PAT at clinically relevant depth of ten centimeters. Our findings have demonstrated the feasibility of the proposed PAT-guided intravascular sonothrombolysis with real-time feedback during the treatment process.

Symptomatic Intracranial Hemorrhage after Ischemic Stroke Treated with Bridging Revascularization Therapy

(1) Background: bridging revascularization therapy is now the standard of care in patients with ischemic stroke due to large vessel occlusion. This study aimed to determine the frequency of symptomatic intracranial hemorrhage (sICH) related to this treatment, and to assess contributing factors and patients' outcomes. (2) Methods: consecutive ischemic stroke patients treated with bridging therapy were prospectively enrolled. sICH (intracranial hemorrhage with an increase in NIHSS score of ≥4 points) was assessed on imaging at 24 h. The functional status of patients was measured at 6 months using the mRS score; (3) Results: 176 patients were included (mean age 68.7 ± 1.2 years, 52.3% women), among whom 15 (8.5%) had sICH. Patients with sICH had more frequent alcohol abuse (30.1% versus 9.7%, p = 0.023), prestroke use of dual antiplatelet therapy (14.3% versus 1.3%, p = 0.002), higher NIHSS scores at admission (median score 20.5 versus 15, p = 0.01), greater systolic blood pressure upon admission, more frequent vascular intracranial calcifications (p = 0.004), leukoaraiosis (p = 0.001), and intracranial atheroma (p = 0.02), and higher neutrophil-to-lymphocyte ratios (p = 0.02) and neutrophil-to-platelet ratios (p = 0.04). At 6-month follow-up, 9 (60%) patients with sICH died, versus 18% of patients without sICH (p < 0.001). Only 1 (7%) patient with sICH had a good functional outcome, defined as an mRS score of 0 to 2, versus 51% of patients without sICH. (4) Conclusions: one in twelve ischemic stroke patients treated with bridging therapy suffered sICH. Given the observed poor outcomes after sICH, further studies are required to better identify patients at risk to help clinicians in guiding therapeutic strategies.

Therapeutic blood-brain barrier modulation and stroke treatment by a bioengineered FZD4-selective WNT surrogate in mice

Derangements of the blood-brain barrier (BBB) or blood-retinal barrier (BRB) occur in disorders ranging from stroke, cancer, diabetic retinopathy, and Alzheimer's disease. The Norrin/FZD4/TSPAN12 pathway activates WNT/β-catenin signaling, which is essential for BBB and BRB function. However, systemic pharmacologic FZD4 stimulation is hindered by obligate palmitoylation and insolubility of native WNTs and suboptimal properties of the FZD4-selective ligand Norrin. Here, we develop L6-F4-2, a non-lipidated, FZD4-specific surrogate which significantly improves subpicomolar affinity versus native Norrin. In Norrin knockout (NdpKO) mice, L6-F4-2 not only potently reverses neonatal retinal angiogenesis deficits, but also restores BRB and BBB function. In adult C57Bl/6J mice, post-stroke systemic delivery of L6-F4-2 strongly reduces BBB permeability, infarction, and edema, while improving neurologic score and capillary pericyte coverage. Our findings reveal systemic efficacy of a bioengineered FZD4-selective WNT surrogate during ischemic BBB dysfunction, with potential applicability to adult CNS disorders characterized by an aberrant blood-brain barrier.

Serum biomarkers to predict hemorrhagic transformation and ischemic stroke outcomes in a prospective cohort study

Ischemic stroke (IS) remains one of the most frequent causes of death and disability worldwide. Identifying possible prognosis factors for IS outcomes, including hemorrhagic transformation (HT), could improve patients' recovery. This study aimed to investigate the potential prognosis role of non-specific laboratory data at admission and baseline MMP-2 and MMP-9 serum levels in predicting HT risk, discharge, and 3-month follow-up status of IS patients. Data from 150 successive acute cerebral infarction patients were analyzed in a prospective cohort study. The active group included patients who developed HT during hospitalization (55 persons). There were no significant differences in age, gender distribution, time to admission, or time to blood sample collection for MMPs measurement between patients in the active and control groups. IS patients from the active group had a significantly higher rate of AF (atrial fibrillation) in the past (p=0.003), while differences in other factors such as diabetes, hypertension, myocardial infarction, previous stroke, obesity, smoking, and alcohol were not significant. Admission NIHSS score and mRS (modified Rankin Scale) values (at discharge and 90 days) were significantly worse in the active group (p<0.001). Among the analyzed admission laboratory factors (glycemia, lipid profile, coagulation panel, inflammatory reaction parameters, MMP-2, MMP-9), INR presented an inverse correlation, with lower values in the HT cohort (univariate analysis - p=0.01, OR=0.11; multivariate analysis - p=0.03, OR=0.09). Further research on larger cohorts is warranted to determine the specific laboratory biomarkers for predicting hemorrhagic transformation and ischemic stroke outcomes.

Real-time tracking of fibrinolysis under constant wall shear and various pulsatile flows in an in-vitro thrombolysis model

A great need exists for the development of a more representative in-vitro model to efficiently screen novel thrombolytic therapies. We herein report the design, validation, and characterization of a highly reproducible, physiological scale, flowing clot lysis platform with real-time fibrinolysis monitoring to screen thrombolytic drugs utilizing a fluorescein isothiocyanate (FITC)-labeled clot analog. Using this Real-Time Fluorometric Flowing Fibrinolysis assay (RT-FluFF assay), a tPa-dependent degree of thrombolysis was observed both via clot mass loss as well as fluorometrically monitored release of FITC-labeled fibrin degradation products. Percent clot mass loss ranged from 33.6% to 85.9% with fluorescence release rates of 0.53 to 1.17 RFU/min in 40 and 1000 ng/mL tPa conditions, respectively. The platform is easily adapted to produce pulsatile flows. Hemodynamics of human main pulmonary artery were mimicked through matching dimensionless flow parameters calculated using clinical data. Increasing pressure amplitude range (4-40 mmHg) results in a 20% increase of fibrinolysis at 1000 ng/mL tPA. Increasing shear flow rate (205-913 s^-1) significantly increases fibrinolysis and mechanical digestion. These findings suggest pulsatile level affects thrombolytic drug activities and the proposed in-vitro clot model offers a versatile testing platform for thrombolytic drug screening.

Exploring the Therapeutic Effect of Neurotrophins and Neuropeptides in Neurodegenerative Diseases: at a Glance

Neurotrophins and neuropeptides are the essential regulators of peripheral nociceptive nerves that help to induce, sensitize, and maintain pain. Neuropeptide has a neuroprotective impact as it increases trophic support, regulates calcium homeostasis, and reduces excitotoxicity and neuroinflammation. In contrast, neurotrophins target neurons afflicted by ischemia, epilepsy, depression, and eating disorders, among other neuropsychiatric conditions. Neurotrophins are reported to inhibit neuronal death. Strategies maintained for "brain-derived neurotrophic factor (BDNF) therapies" are to upregulate BDNF levels using the delivery of protein and genes or compounds that target BDNF production and boosting BDNF signals by expanding with BDNF mimetics. This review discusses the mechanisms of neurotrophins and neuropeptides against acute neural damage as well as highlighting neuropeptides as a potential therapeutic agent against Parkinson's disease (PD), Huntington's disease (HD), Alzheimer's disease (AD), and Machado-Joseph disease (MJD), the signaling pathways affected by neurotrophins and their receptors in both standard and diseased CNS systems, and future perspectives that can lead to the potent application of neurotrophins and neuropeptides in neurodegenerative diseases (NDs).

Temporal trends and outcomes in acute ischaemic stroke patients with a current or historical diagnosis of cancer

BACKGROUND AND PURPOSE

The aim was to evaluate the temporal trends, characteristics and in-hospital outcomes of patients hospitalized with acute ischaemic stroke (AIS) between those with and without current or historical malignancies.

METHODS

Adult hospitalizations with a primary diagnosis of AIS were identified from the National Inpatient Sample database 2007-2017. Logistic regression was used to compare the differences in the utilization of AIS interventions and in-hospital outcomes. For further analysis, subgroup analyses were performed stratified by cancer subtypes.

RESULTS

There were 892,862 hospitalizations due to AIS, of which 108,357 (12.14%) had a concurrent diagnosis of current cancer (3.41%) or historical cancer (8.72%). After adjustment for confounders, patients with current malignancy were more likely to have worse clinical outcomes. The presence of historical cancers was not associated with an increase in poor clinical outcomes. Additionally, AIS patients with current malignancy were less likely to receive intravenous thrombolysis (adjusted odds ratio 0.66, 95% confidence interval 0.63-0.71). Amongst the subgroups of AIS patients treated with intravenous thrombolysis or mechanical thrombectomy, outcomes varied by cancer types. Notably, despite these acute stroke interventions, outcome remains poor in AIS patients with lung cancer.

CONCLUSIONS

Although AIS patients with malignancy generally have worse in-hospital outcomes versus those without, there were considerable variations in these outcomes according to different cancer types and the use of AIS interventions. Finally, treatment of these AIS patients with a current or historical cancer diagnosis should be individualized.

Hemorrhagic Conversion of Acute Ischemic Stroke

Stroke is a leading cause of morbidity and mortality worldwide; a serious complication of ischemic stroke is hemorrhagic transformation. Current treatment of acute ischemic stroke includes endovascular thrombectomy and thrombolytic therapy. Both of these treatment options are linked with increased risks of hemorrhagic conversion. The diagnosis and timely management of patients with hemorrhagic conversion is critically important to patient outcomes. This review aims to discuss hemorrhagic conversion of acute ischemic stroke including discussion of the pathophysiology, review of risk factors, imaging considerations, and treatment of patients with hemorrhagic conversion.

The efficacy and safety of tenecteplase versus alteplase for acute ischemic stroke: an updated systematic review, pairwise, and network meta-analysis of randomized controlled trials

Tenecteplase (TNK) is a promising candidate to replace alteplase as the standard of care for acute ischemic stroke (AIS); however, the optimal dosage is still to be investigated. Therefore, we aim to evaluate the safety and efficacy of TNK versus alteplase and to investigate the optimal TNK dosage. A systematic review, pairwise, and network meta-analysis synthesizing randomized controlled trials (RCTs) from WOS, SCOPUS, EMBASE, and PubMed until July 26^th, 2022. We used the risk ratio (RR) for dichotomous outcomes presented with the corresponding 95% confidence interval (CI). We registered our protocol in PROSPERO with ID: CRD42022352038. Nine RCTs with a total of 3,707 patients were included. TNK significantly led to complete recanalization (RR: 1.27 with 95% CI [1.02, 1.57], P = 0.03); however, we found no difference regarding early neurological improvement (RR: 1.07 with 95% CI [0.94, 1.21], P = 0.33) and excellent neurological recovery (RR: 1.03 with 95% CI [0.96, 1.10], P = 0.42). Also, TNK was similar to alteplase regarding mortality (RR: 0.99 with 95% CI [0.82, 1.18], P = 0.88), intracranial haemorrhage (RR: 1.00 with 95% CI [0.85, 1.18], P = 0.99), and parenchymal hematoma (RR: 1.13 with 95% CI [0.83, 1.54], P = 0.44). TNK in the dose of 0.25 mg is a viable candidate to displace alteplase as the standard of care in patients with an AIS within 4.5 h of presentation due to its better rate of early neurological recovery and non-inferiority in terms of safety outcomes. However, the evidence regarding TNK's role in AIS presenting after 4.5 h from symptoms onset, wake-up stroke, and minor stroke/TIA is still lacking, necessitating further double-blinded pragmatic RCTs in this regard.

Prevention and treatment of atherothrombosis: Potential impact of nanotechnology

Complications with atherosclerosis can often lead to fatal clot formation and blood vessel occlusion - also known as atherothrombosis. A key component to the development of atherosclerosis and atherothrombosis is the endothelium and its ability to regulate the balance between prothrombotic and antithrombotic activities. Endothelial surface glycocalyx has a critical role in maintenance of vascular integrity. The endothelial glycocalyx, nitric oxide, prostacyclins, heparan sulfate, thrombomodulin, and tissue factor pathway inhibitor all prevent thrombosis, while P-selectin, among many other factors, favors thrombosis. However, endothelial dysfunction gives rise to the acceleration of thrombotic development and eventually the requirement of antithrombotic therapy. Most FDA-approved anticoagulant and antiplatelet therapies today carry a side effect profile of major bleed. Within the past five years, several preclinical studies using different endothelial targets and nanotechnology as a drug delivery method have emerged to target the endothelium and to enhance current antithrombosis without increasing bleed risk. While clinical studies are required, this review illustrates the proof-of-concept of nanotechnology in promoting a greater safety and efficacy profile through multiple in vitro and in vivo studies.

A new machine learning algorithm with high interpretability for improving the safety and efficiency of thrombolysis for stroke patients: A hospital-based pilot study

Background

Thrombolysis is the first-line treatment for patients with acute ischemic stroke. Previous studies leveraged machine learning to assist neurologists in selecting patients who could benefit the most from thrombolysis. However, when designing the algorithm, most of the previous algorithms traded interpretability for predictive power, making the algorithms hard to be trusted by neurologists and be used in real clinical practice.

Methods

Our proposed algorithm is an advanced version of classical k-nearest neighbors classification algorithm (KNN). We achieved high interpretability by changing the isotropy in feature space of classical KNN. We leveraged a cohort of 189 patients to prove that our algorithm maintains the interpretability of previous models while in the meantime improving the predictive power when compared with the existing algorithms. The predictive powers of models were assessed by area under the receiver operating characteristic curve (AUC).

Results

In terms of interpretability, only onset time, diabetes, and baseline National Institutes of Health Stroke Scale (NIHSS) were statistically significant and their contributions to the final prediction were forced to be proportional to their feature importance values by the rescaling formula we defined. In terms of predictive power, our advanced KNN (AUC 0.88) outperformed the classical KNN (AUC 0.75, p = 0.0192 ).

Conclusions

Our preliminary results show that the advanced KNN achieved high AUC and identified consistent significant clinical features as previous clinical trials/observational studies did. This model shows the potential to assist in thrombolysis patient selection for improving the successful rate of thrombolysis.

Exosomes-based therapy of stroke, an emerging approach toward recovery

Based on clinical observations, stroke is touted as one of the specific pathological conditions, affecting an individual’s life worldwide. So far, no effective treatment has been introduced to deal with stroke post-complications. Production and release of several neurotrophic factors by different cells exert positive effects on ischemic areas following stroke. As a correlate, basic and clinical studies have focused on the development and discovery of de novo modalities to introduce these factors timely and in appropriate doses into the affected areas. Exosomes (Exo) are non-sized vesicles released from many cells during pathological and physiological conditions and participate in intercellular communication. These particles transfer several arrays of signaling molecules, like several neurotrophic factors into the acceptor cells and induce specific signaling cascades in the favor of cell bioactivity. This review aimed to highlight the emerging role of exosomes as a therapeutic approach in the regeneration of ischemic areas.

Ischemic Stroke Impacts the Gut Microbiome, Ileal Epithelial and Immune Homeostasis

Ischemic stroke critically impacts neurovascular homeostasis, potentially resulting in neurological disorders. However, the mechanisms through which stroke-induced inflammation modifies the molecular and metabolic circuits, particularly in ileal epithelial cells (iECs), currently remain elusive. Using multiomic approaches, we illustrated that stroke impaired the ileal microbiome and associated metabolites, leading to increased inflammatory signals and altered metabolites, potentially deteriorating the iEC homeostasis. Bulk transcriptomic and metabolomic profiling demonstrated that stroke enhanced fatty acid oxidation while reducing the tricarboxylic acid (TCA) cycle in iECs within the first day after stroke. Intriguingly, single-cell RNA sequencing analysis revealed that stroke dysregulated cell-type-specific gene responses within iECs and reduced frequencies of goblet and tuft cells. Additionally, stroke augmented interleukin-17A+ γδ T cells but decreased CD4+ T cells in the ileum. Collectively, our findings provide a comprehensive overview of stroke-induced intestinal dysbiosis and unveil responsive gene programming within iECs with implications for disease development.

Bedside Fluorescence Microangiography for Frostbite Diagnosis in the Emergency Department

Frostbite leads to progressive ischemia eventually causing tissue necrosis if not quickly reversed. Patients with frostbite tend to present to the emergency department (ED) for assessment and treatment. Acute management includes rewarming, pain management, and (when indicated) thrombolytic therapy. Thrombolytic therapy in severe frostbite injury may decrease rates of amputation and improve patient outcomes. Fluorescence microangiography (FMA) has been used to distinguish between perfused and non-perfused tissue. The purpose of this study was to evaluate the potential role of FMA in the acute care of patients with frostbite, specifically its role as a tool to identify perfusion deficit following severe frostbite injury, and to explore its role in time to tissue plasminogen activator (tPA). Methods: This retrospective analysis included all patients from December 2020–March 2021 who received FMA in a single ED as part of their initial frostbite evaluation. In total, 42 patients presented to the ED with concern for frostbite and were evaluated using FMA. Results: Mean time from arrival in the ED to FMA was 46.3 minutes. Of the 42 patients, 14 had clinically significant perfusion deficits noted on FMA and received tPA. Mean time to tPA (measured from ED arrival to administration of tPA) for these patients was 117.4 minutes. This is significantly faster than average historical times at our institution of 240-300 minutes. Conclusion: Bedside FMA provides objective information regarding perfusion deficits and allows for faster decision-making and improved times to tPA. Fluorescence microangiography shows promise for quick and efficient evaluation of perfusion deficits in frostbite-injured patients. This could lead to faster tPA administration and potentially greater rates of tissue salvage after severe frostbite injury.

The feasibility and accuracy of machine learning in improving safety and efficiency of thrombolysis for patients with stroke: Literature review and proposed improvements

In the treatment of ischemic stroke, timely and efficient recanalization of occluded brain arteries can successfully salvage the ischemic brain. Thrombolysis is the first-line treatment for ischemic stroke. Machine learning models have the potential to select patients who could benefit the most from thrombolysis. In this study, we identified 29 related previous machine learning models, reviewed the models on the accuracy and feasibility, and proposed corresponding improvements. Regarding accuracy, lack of long-term outcome, treatment option consideration, and advanced radiological features were found in many previous studies in terms of model conceptualization. Regarding interpretability, most of the previous models chose restrictive models for high interpretability and did not mention processing time consideration. In the future, model conceptualization could be improved based on comprehensive neurological domain knowledge and feasibility needs to be achieved by elaborate computer science algorithms to increase the interpretability of flexible algorithms and shorten the processing time of the pipeline interpreting medical images.

A Fibrinogen-Mimicking, Activated-Platelet-Sensitive Nanocoacervate Enhances Thrombus Targeting and Penetration of Tissue Plasminogen Activator for Effective Thrombolytic Therapy

The development of a fibrinolytic system with long circulation time, high thrombus targeting, efficient thrombus penetration, effective thrombolysis, and minimal hemorrhagic risk remains a major challenge. Herein, inspired by fibrinogen binding to activated platelets in thrombosis, this article reports a fibrinogen-mimicking, activated-platelet-sensitive nanocoacervate to enhance thrombus penetration of tissue plasminogen activator (tPA) for targeted thrombolytic therapy. This biomimetic nanothrombolytic system, denoted as RGD-Chi@tPA, is constructed by "one-pot" coacervation through electrostatic interactions between positively charged arginine-glycine-aspartic acid (RGD)-grafted chitosan (RGD-Chi) and negatively charged tPA. Flow cytometry and confocal laser scanning microscopy measurements show targeting of RGD-Chi@tPA to activated platelets. Controlled tPA release triggered by activated platelets at a thrombus site is demonstrated. Its targeted fibrinolytic and thrombolytic activities are measured in in vitro models. The pharmacokinetic profiles show that RGD-Chi@tPA can significantly prolong circulation time compared to free tPA. In a mouse tail thrombus model, RGD-Chi@tPA displays efficient thrombus targeting and penetration, enabling a complete vascular recanalization as confirmed by the fluorescence imaging, histochemical assay, and laser speckle contrast imager. Consequently, RGD-Chi@tPA induces a substantial enhancement in thrombolysis with minimal hemorrhagic risk compared to free tPA. This simple, effective, and safe platform holds great promise for the development of thrombolytic nanomedicines.

A Nursing Approach to Improving Critical Care Compliance With Vital Signs and Neurological Assessments in Post-IV-Alteplase Stroke Patients

Ischemic stroke represents 87% of all strokes. As global initiatives move forward with stroke care, health care providers and institutions will be called on to deliver the most current evidence-based care. The American Heart Association/American Stroke Association (AHA/ASA) estimates that 795 000 strokes occur each year; 610 000 are new strokes, and 185 000 are recurrent strokes. Eighty-seven percent are ischemic strokes; the overall mortality rate from stroke was 273 000, which makes stroke the fifth leading cause of death and the leading cause of disability in the United States. Stroke costs the United States an estimated $34 billion each year. This article outlines a nursing intervention regarding the use of intravenous thrombolytic therapy for treating acute ischemic stroke, the risk factors related to IV-alteplase, best-practice protocols, and the nursing role in efforts to deliver safe care. The conclusion reveals the need for health care organizations to explore opportunities, continually inspire innovation at the bedside, highlight nursing's essential contribution to acute stroke care, and encourage publishing improvements in patient care and the nurse practice environment.

Hidden Potential of Highly Efficient and Widely Accessible Thrombolytic Staphylokinase

Stroke burden is substantially increasing but current therapeutic drugs are still far from ideal. Here we highlight the vast potential of staphylokinase as an efficient, fibrin-selective, inexpensive, and evolvable thrombolytic agent. The emphasis is escalated by new recent findings. Staphylokinase nonimmunogenic variant was proven noninferior to alteplase in a clinical trial, with decreased risk of intracranial hemorrhage and the advantage of single bolus administration. Furthermore, our detailed kinetic analysis revealed a new staphylokinase limiting bottleneck whose elimination might provide up to 1000-fold higher activity than the clinically approved alteplase. This knowledge of limitations unlocks new possibilities for improvements that are now achievable by the community of protein engineers who have the required expertise and are ready to transform staphylokinase into a powerful molecule. Collectively, the noninferiority and safety of nonimmunogenic staphylokinase together with the newly identified effectivity limitation make staphylokinase a perfect candidate for further exploration, modification, and advancement to make it the next-generation widely accessible thrombolytic drug effectively treating stroke all around the world, including middle- and low-income countries.

Ex Vivo Machine Thrombolysis Reduces Rethrombosis Rates in Salvaged Thrombosed Myocutaneous Flaps in Swine

BACKGROUND

There is a risk for thrombotic complications (2 to 5 percent) associated with microsurgical reconstruction. Current thrombolytic therapy has a salvage rate between 60 and 70 percent, but it is afflicted by bleeding complications (2 to 6 percent). The use of machine perfusion for delivering thrombolytic agents is a new method that could potentially reduce these complications. In this article, the authors compared flap salvage outcomes comparing machine thrombolysis versus a manual flush with tissue plasminogen activator.

METHODS

Sixteen bilateral flaps (12 × 9 cm) were dissected from eight female Dutch Landrace pigs (70 kg). Thrombosis was induced in free rectus abdominis flaps by clamping the pedicle's veins for 2 hours. Flaps were either thrombolysed with 2 mg tissue plasminogen activator (1 mg/ml) during 2 hours of machine perfusion (perfusion group; n = 8) or injected intraarterially (manual group; n = 8) before replantation. Near-infrared fluorescence angiography was used to confirm thrombus formation and to assess tissue perfusion; muscle biopsy specimens were analyzed for ischemia/reperfusion injury directly after thrombolysis and 15 hours after replantation.

RESULTS

A higher incidence of secondary thrombosis was seen in the manual group compared to the perfusion group ( n = 6 versus n = 0, respectively; p < 0.001), resulting in two complete flap failures. Fifteen hours after replantation, mean fluorescence intensities were 13.0 (95 percent CI, 10.1 to 15.8) and 24.6 (95 percent CI, 22.0 to 27.2) in the perfusion and manual group, respectively ( p < 0.001), and mean muscle injury scores were comparable, measuring 7.5 ± 1.5.

CONCLUSION

Two hours of machine thrombolysis of compromised flaps in a porcine model showed higher salvage rates compared to a manual injection with tissue plasminogen activator and reduced the incidence of secondary thrombosis.

CLINICAL RELEVANCE STATEMENT

Using machine perfusion systems for ex vivo thrombolysis provides the benefits of local treatment of a composite tissue without the risk of systemic complications and may improve salvage rates and reduce the incidence of secondary thrombosis.

Cannabinoids as Glial Cell Modulators in Ischemic Stroke: Implications for Neuroprotection

Stroke is the second leading cause of death worldwide following coronary heart disease. Despite significant efforts to find effective treatments to reduce neurological damage, many patients suffer from sequelae that impair their quality of life. For this reason, the search for new therapeutic options for the treatment of these patients is a priority. Glial cells, including microglia, astrocytes and oligodendrocytes, participate in crucial processes that allow the correct functioning of the neural tissue, being actively involved in the pathophysiological mechanisms of ischemic stroke. Although the exact mechanisms by which glial cells contribute in the pathophysiological context of stroke are not yet completely understood, they have emerged as potentially therapeutic targets to improve brain recovery. The endocannabinoid system has interesting immunomodulatory and protective effects in glial cells, and the pharmacological modulation of this signaling pathway has revealed potential neuroprotective effects in different neurological diseases. Therefore, here we recapitulate current findings on the potential promising contribution of the endocannabinoid system pharmacological manipulation in glial cells for the treatment of ischemic stroke.

Ultrasound-Guided Intravascular Sonothrombolysis With a Dual Mode Ultrasound Catheter: In Vitro Study

Thromboembolism in vessels often leads to stroke or heart attack and even sudden death unless brought under control. Sonothrombolysis based on ultrasound contrast agents has shown promising outcome in effective treatment of thromboembolism. Intravascular sonothrombolysis transducer was reported recently for unprecedented sonothrombolysis in vitro. However, it is necessary to provide an imaging guide during thrombolysis in clinical applications for optimal treatment efficiency. In this article, a dual mode ultrasound catheter was developed by combining a 16-MHz high-frequency element (imaging transducer) and a 220-kHz low-frequency element (treatment transducer) for sonothrombolysis in vitro. The treatment transducer was designed with a 20-layer PZT-5A stack with the aperture size of 1.2×1.2 mm², and the imaging transducer with the aperture size of 1.2×1.2 mm² was attached in front of the treatment transducer. Both transducers were assembled into a customized 2-lm 10-Fr catheter. In vitro experiment was carried out using a bovine blood clot. Imaging tests were conducted, showing that the backscattering signals can be obtained with a high signal-to-noise ratio (SNR) for the 16-MHz imaging transducer. Sonothrombolysis was performed successfully that the volume of clot was reduced significantly after the 30-min treatment. The size changes of clot were observed clearly using the 16-MHz M-mode imaging during the thrombolysis. The findings suggest that the proposed ultrasound-guided intravascular sonothrombolysis can be enhanced since the position of treatment transducer can be adjusted with the target at the clot due to the imaging guide.

Invasive and Pharmacological Treatment of Deep Vein Thrombosis: a Scoping Review

The annual occurrence of venous thromboembolism (VTE) is 300,000-600,000 cases in the United States and 700,000 in Europe. VTE includes deep venous thrombosis (DVT) of upper or lower extremities, superior and inferior vena cava thrombosis, and pulmonary embolism (PE) as well. The primary treatment of DVT includes oral anticoagulation to prevent the progression of the thrombus and decrease the risk of pulmonary embolism. Depending on the symptoms, more invasive treatments can be applied to target the iliofemoral thrombus and its removal. However, less emphasis is given to acute symptomatology, early recovery of function, quality of life improvement, and the individualized likelihood of developing post-thrombotic syndrome. While invasive therapy has been used to enhance the acute management of iliofemoral DVT, our knowledge about the overall outcomes associated with the invasive treatment of VTE is still limited. In this review, we illustrate the available data on pharmacological and endovascular management of iliofemoral VTE, including therapies such as catheter-directed thrombolysis (CDT), mechanical thrombectomy (PMT), and pharmacomechanical catheter-directed thrombolysis (PCDT).

Calcitriol ameliorates brain injury in the rat model of cerebral ischemia-reperfusion through Nrf2/HO-1 signalling axis: An in silico and in vivo study

OBJECTIVES

Calcitriol has been revealed to exert neuroprotective effects in ischemic stroke; however, its role and the underlying mechanisms in brain injury induced by ischemia are not well known. The purpose of this study was to determine the neuroprotective effects of calcitriol pretreatment and to assess the possible neuroprotective function of nuclear factor erythroid 2-related factor 2 (Nrf2)/ heme oxygenase-1 (HO-1) signalling pathway against brain ischemia/reperfusion (I/R) injury in the rat models which was followed by a bioinformatics approach.

METHODS

The experimental I/R model induction was performed in male Wistar rats for 1 h followed by 23 h reperfusion. Calcitriol was administered intraperitoneally for 7 days prior to stroke. Following ischemia induction 24 h later, neurobehavioral deficits and infarction volume were examined. Oxidative stress was assessed by measurement of malondialdehyde (MDA), nitric oxide (NO) and total antioxidant capacity (TAC). The protein and mRNA expression of HO-1 and Nrf2 were determined by western blot and reverse transcription polymerase chain reaction (RT-PCR), respectively. A molecular docking approach was applied to identify the interaction value of Keap1 with calcitriol.

RESULTS

Our data demonstrated that calcitriol significantly decreased infarction volume and ameliorated neurological deficits in brain I/R. MDA and NO levels were decreased and TAC level was elevated significantly after calcitriol pretreatment. Furthermore, calcitriol upregulated the expression of HO-1 and Nrf2 protein and mRNA in ischemic brain. Molecular modelling demonstrated that calcitriol could interact with the pocket of Keap1 by an appropriate binding energy.

CONCLUSIONS

The results indicate that calcitriol protects the brain against I/R injury. This effect may pass through inhibition of oxidative stress and Nrf2/HO-1 pathway activation and this may arise by interaction of Keap1 and calcitriol.

Shorter Intensive Care Unit Stay (12 Hours) Post Thrombolysis Is Safe and Reduces Length of Stay for Minor Stroke Patients

The current standard of practice for patients with acute ischemic stroke treated with intravenous tissue-type plasminogen activator (tPA) requires critical monitoring for 24-hours post-treatment due to the risk of symptomatic intracranial hemorrhage (sICH). This is a costly and resource intensive practice. In this study, we evaluated the safety and efficacy of this standard 24-hour ICU monitoring period compared with a shorter 12-hour ICU monitoring period for minor stroke patients (NIHSS 0-5) treated with tPA only. Stroke mimics and those who underwent thrombectomy were excluded. The primary outcome was length of hospital stay. Secondary outcome measures included sICH, deep venous thrombosis (DVT), pulmonary embolism (PE), pneumonia, favorable discharge to home or acute rehabilitation, readmission within 30 days, and favorable functional outcome defined as modified Rankin scale (mRS) of 0-2 at 90 days. Of the 122 patients identified, 77 were in the 24-hour protocol and 45 were in 12-hour protocol. There was significant difference in length of hospital stay for the 24-hour ICU protocol (2.8 days) compared with the 12-hour ICU protocol (1.8 days) ( P < 0.001). Although not statistically significant, the 12-hour group had favorable rates of sICH, 30-day readmission rates, favorable discharge disposition and favorable functional outcome. Rates of DVT, PE and aspiration pneumonia were identical between the groups. Compared with 24-hour ICU monitoring, 12-hour ICU monitoring after thrombolysis for minor acute ischemic stroke was not associated with any increase in adverse outcomes. A randomized trial is needed to verify these findings.

Transcranial focused ultrasound stimulation reduces vasogenic edema after middle cerebral artery occlusion in mice

Blood-brain barrier (BBB) disruption underlies the vasogenic edema and neuronal cell death induced by acute ischemic stroke. Reducing this disruption has therapeutic potential. Transcranial focused ultrasound stimulation has shown neuromodulatory and neuroprotective effects in various brain diseases including ischemic stroke. Ultrasound stimulation can reduce inflammation and promote angiogenesis and neural circuit remodeling. However, its effect on the BBB in the acute phase of ischemic stroke is unknown. In this study of mice subjected to middle cerebral artery occlusion for 90 minutes, low-intensity low-frequency (0.5 MHz) transcranial focused ultrasound stimulation was applied 2, 4, and 8 hours after occlusion. Ultrasound stimulation reduced edema volume, improved neurobehavioral outcomes, improved BBB integrity (enhanced tight junction protein ZO-1 expression and reduced IgG leakage), and reduced secretion of the inflammatory factors tumor necrosis factor-α and activation of matrix metalloproteinase-9 in the ischemic brain. Our results show that low-intensity ultrasound stimulation attenuated BBB disruption and edema formation, which suggests it may have therapeutic use in ischemic brain disease as a protector of BBB integrity.

Tenecteplase vs. alteplase for acute ischemic stroke: a systematic review

INTRODUCTION

Thrombolysis for acute ischemic stroke (AIS) with alteplase is the currently approved therapy for patients who present within 4.5 h of symptom onset and meet criteria. Recently, there has been interest in the thrombolytic tenecteplase, a modified version of alteplase, due to its lower cost, ease of administration, and studies reporting better outcomes when compared to alteplase. This systematic review compares the efficacy of tenecteplase vs. alteplase with regard to three outcomes: (1) rate of symptomatic hemorrhage, (2) functional outcome at 90 days, and (3) reperfusion grade after thrombectomy to compare the efficacy of both thrombolytics in AIS METHODS: The search was conducted in August 2021 in PubMed, filtered for randomized controlled trials, and studies in English. The main search term was "tenecteplase for acute stroke."

RESULTS

A total of 6 randomized clinical trials including 1675 patients with AIS was included. No one's study compared alteplase to tenecteplase with all three outcomes after acute ischemic stroke; however, by using a combination of the results, this systematic review summarizes whether tenecteplase outperforms alteplase.

CONCLUSIONS

The available evidence suggests that tenecteplase appears to be a better thrombolytic agent for acute ischemic stroke when compared to alteplase.

Mechanical Thrombectomy With and Without Intravenous Tissue Plasminogen Activator for Acute Ischemic Stroke: A Systematic Review and Meta-Analysis Using Nested Knowledge

Background: Mechanical thrombectomy (MT) is now the standard-of-care treatment for acute ischemic stroke (AIS) of the anterior circulation and may be performed irrespective of intravenous tissue plasminogen activator (IV-tPA) eligibility prior to the procedure. This study aims to understand better if tPA leads to higher rates of reperfusion and improves functional outcomes in AIS patients after MT and to simultaneously evaluate the functionality and efficiency of a novel semi-automated systematic review platform. Methods: The Nested Knowledge AutoLit semi-automated systematic review platform was utilized to identify randomized control trials published between 2010 and 2021 reporting the use of mechanical thrombectomy and IV-tPA (MT+tPA) vs. MT alone for AIS treatment. The primary outcome was the rate of successful recanalization, defined as thrombolysis in cerebral infarction (TICI) scores ≥2b. Secondary outcomes included 90-day modified Rankin Scale (mRS) 0-2, 90-day mortality, distal embolization to new territory, and symptomatic intracranial hemorrhage (sICH). A separate random effects model was fit for each outcome measure. Results: We subjectively found Nested Knowledge to be highly streamlined and effective at sourcing the correct literature. Four studies with 1,633 patients, 816 in the MT+tPA arm and 817 in the MT arm, were included in the meta-analysis. In each study, patient populations consisted of only tPA-eligible patients and all imaging and clinical outcomes were adjudicated by an independent and blinded core laboratory. Compared to MT alone, patients treated with MT+tPA had higher odds of eTICI ≥2b (OR = 1.34 [95% CI: 1.10; 1.63]). However, there were no statistically significant differences in the rates of 90-day mRS 0-2 (OR = 0.98 [95% CI: 0.77; 1.24]), 90-day mortality (OR = 0.94 [95% CI: 0.67; 1.32]), distal emboli (OR = 0.94 [95% CI: 0.25; 3.60]), or sICH (OR = 1.17 [95% CI: 0.80; 1.72]). Conclusions: Administering tPA prior to MT may improve the rates of recanalization compared to MT alone in tPA-eligible patients being treated for AIS, but a corresponding improvement in functional and safety outcomes was not present in this review. Further studies looking at the role of tPA before mechanical thrombectomy in different cohorts of patients could better clarify the role of tPA in the treatment protocol for AIS.

Drug Delivery Challenges in Brain Disorders across the Blood-Brain Barrier: Novel Methods and Future Considerations for Improved Therapy

Due to the physiological and structural properties of the blood-brain barrier (BBB), the delivery of drugs to the brain poses a unique challenge in patients with central nervous system (CNS) disorders. Several strategies have been investigated to circumvent the barrier for CNS therapeutics such as in epilepsy, stroke, brain cancer and traumatic brain injury. In this review, we summarize current and novel routes of drug interventions, discuss pharmacokinetics and pharmacodynamics at the neurovascular interface, and propose additional factors that may influence drug delivery. At present, both technological and mechanistic tools are devised to assist in overcoming the BBB for more efficient and improved drug bioavailability in the treatment of clinically devastating brain disorders.

Dual-Frequency Intravascular Sonothrombolysis: An In Vitro Study

Thrombo-occlusive disease is one of the leading causes of death worldwide. There has been active research on safe and effective thrombolysis in preclinical and clinical studies. Recently, the dual-frequency transcutaneous sonothrombolysis with contrast agents [microbubbles (MBs)] has been reported to be more efficient in trigging the acoustic cavitation, which leads to a higher lysis rate. Therefore, there is increasing interest in applying dual-frequency technique for more significant efficacy improvement in intravascular sonothrombolysis since a miniaturized intravascular ultrasound transducer typically has a limited power output to fully harness cavitation effects. In this work, we demonstrated this efficacy enhancement by developing a new broadband intravascular transducer and testing dual-frequency sonothromblysis in vitro. A broadband intravascular transducer with a center frequency of 750 kHz and a footprint size of 1.4 mm was designed, fabricated, and characterized. The measured -6-dB fractional bandwidth is 68.1%, and the peak negative pressure is 1.5 MPa under the driving voltage of 80 V_pp. By keeping one frequency component at 750 kHz, the second frequency component was selected from 450 to 650 kHz with an interval of 50 kHz. The in vitro sonothrombolysis tests were conducted with a flow model and the results indicated that the MB-mediated, dual-frequency (750+500 kHz) sonothrombolysis yields an 85% higher lysis rate compared with the single-frequency treatment, and the lysis rate of dual-frequency sonothrombolysis increases with the difference between the two frequency components. These findings suggest a dual-frequency excitation technique for more efficient intravascular sonothrombolysis than conventional single-frequency excitation.

Posttreatment Strategy Against Hypoxia and Ischemia Based on Selective Targeting of Nonnuclear Estrogen Receptors with PaPE-1

Newly synthesized Pathway Preferential Estrogen-1 (PaPE-1) selectively activates membrane estrogen receptors (mERs), namely, mERα and mERβ, and has been shown to evoke neuroprotection; however, its effectiveness in protecting brain tissue against hypoxia and ischemia has not been verified in a posttreatment paradigm. This is the first study showing that a 6-h delayed posttreatment with PaPE-1 inhibited hypoxia/ischemia-induced neuronal death, as indicated by neutral red uptake in mouse primary cell cultures in vitro. The effect was accompanied by substantial decreases in neurotoxicity and neurodegeneration in terms of LDH release and Fluoro-Jade C staining of damaged cells, respectively. The mechanisms of the neuroprotective action of PaPE-1 also involved apoptosis inhibition demonstrated by normalization of both mitochondrial membrane potential and expression levels of apoptosis-related genes and proteins such as Fas, Fasl, Bcl2, FAS, FASL, BCL2, BAX, and GSK3β. Furthermore, PaPE-1-evoked neuroprotection was mediated through a reduction in ROS formation and restoration of cellular metabolic activity that had become dysregulated due to hypoxia and ischemia. These data provide evidence that targeting membrane non-GPER estrogen receptors with PaPE-1 is an effective therapy that protects brain neurons from hypoxic/ischemic damage, even when applied with a 6-h delay from injury onset.

The effect of blood cells retained in rat livers during static cold storage on viability outcomes during normothermic machine perfusion

In transplantation, livers are transported to recipients using static cold storage (SCS), whereby livers are exposed to cold ischemic injury that contribute to post-transplant risk factors. We hypothesized that flushing organs during procurement with cold preservation solutions could influence the number of donor blood cells retained in the allograft thereby exacerbating cold ischemic injury. We present the results of rat livers that underwent 24 h SCS after being flushed with a cold University of Wisconsin (UW) solution versus room temperature (RT) lactated ringers (LR) solution. These results were compared to livers that were not flushed prior to SCS and thoroughly flushed livers without SCS. We used viability and injury metrics collected during normothermic machine perfusion (NMP) and the number of retained peripheral cells (RPCs) measured by histology to compare outcomes. Compared to the cold UW flush group, livers flushed with RT LR had lower resistance, lactate, AST, and ALT at 6 h of NMP. The number of RPCs also had significant positive correlations with resistance, lactate, and potassium levels and a negative correlation with energy charge. In conclusion, livers exposed to cold UW flush prior to SCS appear to perform worse during NMP, compared to RT LR flush.

Imaging Acute Stroke: From One-Size-Fit-All to Biomarkers

In acute stroke management, time window has been rigidly used as a guide for decades and the reperfusion treatment is only available in the first few limited hours. Recently, imaging-based selection of patients has successfully expanded the treatment window out to 16 and even 24 h in the DEFUSE 3 and DAWN trials, respectively. Recent guidelines recommend the use of imaging techniques to guide therapeutic decision-making and expanded eligibility in acute ischemic stroke. A tissue window is proposed to replace the time window and serve as the surrogate marker for potentially salvageable tissue. This article reviews the evolution of time window, addresses the advantage of a tissue window in precision medicine for ischemic stroke, and discusses both the established and emerging techniques of neuroimaging and their roles in defining a tissue window. We also emphasize the metabolic imaging and molecular imaging of brain pathophysiology, and highlight its potential in patient selection and treatment response prediction in ischemic stroke.

Ensemble learning accurately predicts the potential benefits of thrombolytic therapy in acute ischemic stroke

Background

Finding methods to accurately predict the final infarct volumes for acute ischemic stroke patients with full or no recanalization would significantly help to evaluate the potential benefits of thrombolytic therapy. We proposed such a method by constructing a model of ensemble deep learning and machine learning using diffusion-weighted imaging (DWI) only.

Methods

The proposed prediction model (named AUNet) combines an adaptive linear ensemble model (ALEM) of machine learning and a deep U-Net network with an accelerated non-local module (U-NL-Net) to learn voxel-wise and spatial features, respectively. Of 40 patients with acute ischemic stroke who received thrombolytic therapy, 17 were fully recanalized, 14 were not recanalized, and nine were partially recanalized. The AUNet was separately trained for full recanalization conditions (AUNetR) and no recanalization (AUNetN) as the best and worst outcomes of thrombolysis, respectively.

Results

AUNet performed significantly better in predicting the final infarct volumes in both the recanalization and non-recanalization conditions [area under the receiver operating characteristic curve (AUC) =0.898±0.022, recanalization; AUC =0.875±0.036, non-recanalization: Matthew's correlation coefficient (MCC) =0.863±0.033, recanalization; MCC =0.851±0.025, non-recanalization] than the fixed-thresholding method (AUC =0.776±0.021, P<0.0001, recanalization; AUC =0.692±0.023, P<0.0001, non-recanalization: MCC =0.742±0.035, recanalization; MCC =0.671±0.024, non-recanalization), the logistic regression method (AUC =0.797±0.023, P<0.003, recanalization; AUC =0.751±0.030, P<0.003, non-recanalization: MCC =0.762±0.035, recanalization; MCC =0.730±0.031, non-recanalization), and a recently developed convolutional neural network (AUC =0.814±0.013, P<0.003, recanalization; AUC =0.781±0.027, P<0.003, non-recanalization: MCC =792±0.022, recanalization; MCC =0.758±0.016, non-recanalization). The potential benefit of thrombolysis calculated from AUNetR and AUNetN showed large individual differences (from 12.81% to 239.73%).

Conclusions

AUNet improved predictive accuracy over current state-of-the-art methods. More importantly, the accurate prediction of infarct volumes under different recanalization conditions may provide benefitial information for physicians in selecting suitable patients for thrombolytic therapy.

Magneto-sonothrombolysis with combination of magnetic microbubbles and nanodroplets

This paper reports a novel technique using the rotational magnetic field oscillation and low-intensity sub-megahertz ultrasound stimulation of magnetic microbubbles (MMBs) to promote the nanodroplets (NDs) phase transition and improve the permeation of NDs into the blood clot fibrin network to enhance the sonothrombolysis efficiency. In this study, the influence of different treatment methods with a combination of MMBs and NDs on the thrombolysis rate of both unretracted and retracted clots were investigated, including the stable and inertial cavitation, tPA effects, MMBs/NDs concentration ratio, sonication factors (input voltage, duty cycle) and rotational magnetic field factors (flux density, frequency). We demonstrated that tPA-mediated magneto-sonothrombolysis in combining NDs with MMBs could significantly enhance in vitro lysis of both unretracted clots (85 ± 8.3%) and retracted clots (57 ± 6.5%) in a flow model with 30 min treatment. The results showed that the combination of MMBs and NDs substantially improves in vitro lysis of blood clots with an unprecedented lysis rate.

Molecular Mechanisms of Neuroimmune Crosstalk in the Pathogenesis of Stroke

Stroke disrupts the homeostatic balance within the brain and is associated with a significant accumulation of necrotic cellular debris, fluid, and peripheral immune cells in the central nervous system (CNS). Additionally, cells, antigens, and other factors exit the brain into the periphery via damaged blood–brain barrier cells, glymphatic transport mechanisms, and lymphatic vessels, which dramatically influence the systemic immune response and lead to complex neuroimmune communication. As a result, the immunological response after stroke is a highly dynamic event that involves communication between multiple organ systems and cell types, with significant consequences on not only the initial stroke tissue injury but long-term recovery in the CNS. In this review, we discuss the complex immunological and physiological interactions that occur after stroke with a focus on how the peripheral immune system and CNS communicate to regulate post-stroke brain homeostasis. First, we discuss the post-stroke immune cascade across different contexts as well as homeostatic regulation within the brain. Then, we focus on the lymphatic vessels surrounding the brain and their ability to coordinate both immune response and fluid homeostasis within the brain after stroke. Finally, we discuss how therapeutic manipulation of peripheral systems may provide new mechanisms to treat stroke injury.

Angioedema Secondary to tPA Use in Acute Ischemic Stroke Patient with Hypertension: A Case Report

Introduction

A well-documented complication of administering tissue plasminogen activator (tPA) in stroke patients is acute intracranial bleeding. A lesser known but still significant complication is angioedema secondary to tPA administration, which can develop in certain individuals with risk factors such as angiotensin converting enzyme (ACE) inhibitor use and location of the stroke. Knowing the potential for this life-threatening complication and being prepared for its proper management is vital for emergency physicians.

Case Report

We report a 53-year-old Black female who presented to the emergency department with sudden onset of slurred speech and a facial droop. She was found to have an acute ischemic stroke and tPA was administered. She subsequently developed angioedema. Retrospectively, the patient was found to have risk factors that are thought to predispose patients to tPA-induced angioedema.

Conclusion

Risk factors associated with angioedema secondary to tPA administration have been documented in patients taking ACE inhibitors, as well as patients who develop strokes in the frontal lobe. While many cases may be mild, some patients may develop life-threatening angioedema. Although this complication does not necessarily contraindicate tPA use, it is prudent for the emergency physician to be vigilant for its development, prepared for its treatment, and to be diligent in assessing the need for control of the patient’s airway.

Stroke or No Stroke: A Case Report of Bilingual Aphasia

Introduction

Bilingual aphasia is an atypical stroke presentation in the multilingual patient where an isolated aphasia occurs in one language while the other remains unaffected.

Case Report

A multilingual male presented to the emergency department with expressive aphasia to English but who was still able to speak fluently in French. Receptive English was preserved. While his National Institute of Health Stroke Scale score was technically zero, his pure aphasia component qualified him as an exception. He regained some repetitive English, so fibrinolyitic therapy was not initiated.

Conclusion

Bilingual aphasia is an indication for fibrinolysis given the impact that a pure aphasic stroke has on quality of life.

Post-Treatment with Amorfrutin B Evokes PPARγ-Mediated Neuroprotection against Hypoxia and Ischemia

In this study, we demonstrate for the first time that amorfrutin B, a selective modulator of peroxisome proliferator-activated receptor gamma—PPARγ, can protect brain neurons from hypoxia- and ischemia-induced degeneration when applied at 6 h post-treatment in primary cultures. The neuroprotective effect of amorfrutin B suggests that it promotes mitochondrial integrity and is capable of inhibiting reactive oxygen species—ROS activity and ROS-mediated DNA damage. PPARγ antagonist and Pparg mRNA silencing abolished the neuroprotective effect of amorfrutin B, which points to agonistic action of the compound on the respective receptor. Interestingly, amorfrutin B stimulated the methylation of the Pparg gene, both during hypoxia and ischemia. Amorfrutin B also increased the protein level of PPARγ during hypoxia but decreased the mRNA and protein levels of PPARγ during ischemia. Under ischemic conditions, amorfrutin B-evoked hypermethylation of the Pparg gene is in line with the decrease in the mRNA and protein expression of PPARγ. However, under hypoxic conditions, amorfrutin B-dependent hypermethylation of the Pparg gene does not explain the amorfrutin B-dependent increase in receptor protein expression, which suggests other regulatory mechanisms. Other epigenetic parameters, such as HAT and/or sirtuins activities, were affected by amorfrutin B under hypoxic and ischemic conditions. These properties position the compound among the most promising anti-stroke and wide-window therapeutics.

Thrombolytic Therapy During ex-vivo Normothermic Machine Perfusion of Human Livers Reduces Peribiliary Vascular Plexus Injury

Background: A major limitation in expanding the use of donation after circulatory death (DCD) livers in transplantation is the increased risk of graft failure secondary to ischemic cholangiopathy. Warm ischemia causes thrombosis and injury to the peribiliary vascular plexus (PVP), which is supplied by branches of the hepatic artery, causing higher rates of biliary complications in DCD allografts.

Aims/Objectives: We aimed to recondition discarded DCD livers with tissue plasminogen activator (tPA) while on normothermic machine perfusion (NMP) to improve PVP blood flow and reduce biliary injury.

Methods: Five discarded DCD human livers underwent 12 h of NMP. Plasminogen was circulated in the base perfusate prior to initiation of perfusion and 1 mg/kg of tPA was administered through the hepatic artery at T = 0.5 h. Two livers were split prior to perfusion (S1, S2), with tPA administered in one lobe, while the other served as a control. The remaining three whole livers (W1-W3) were compared to seven DCD control liver perfusions (C1-C7) with similar hepatocellular and biliary viability criteria. D-dimer levels were measured at T = 1 h to verify efficacy of tPA. Lactate, total bile production, bile pH, and difference in biliary injury scores before and after perfusion were compared between tPA and non-tPA groups using unpaired, Mann-Whitney tests.

Results: Average weight-adjusted D-dimer levels were higher in tPA livers in the split and whole-liver model, verifying drug function. There were no differences in perfusion hepatic artery resistance, portal vein resistance, and arterial lactate between tPA livers and non-tPA livers in both the split and whole-liver model. However, when comparing biliary injury between hepatocellular and biliary non-viable whole livers, tPA livers had significantly lower PVP injury scores (0.67 vs. 2.0) and mural stroma (MS) injury scores (1.3 vs. 2.7).

Conclusion: This study demonstrates that administration of tPA into DCD livers during NMP can reduce PVP and MS injury. Further studies are necessary to assess the effect of tPA administration on long term biliary complications.

Management dilemmas in acute ischemic stroke and concomitant acute pulmonary embolism: Case series and literature review

BACKGROUND

Pulmonary embolism (PE) and acute ischemic stroke (AIS) are common disorders with high morbidity and mortality, rarely presenting simultaneously. There is a paucity of data regarding the management of this uncommon presentation. The treatment of these two entities is complex in the acute phase due to the concomitant need for thrombolysis in AIS and anticoagulation for PE.

METHODS

We retrospectively reviewed confirmed ischemic stroke cases to identify patients presented with simultaneous PE from June 2018 to May 2019. Additionally, a literature review was performed. Two reviewers assessed the manuscripts' quality, and relevant data regarding clinical course and management was extracted.

RESULTS

We reviewed 439 patient charts, identifying two cases of concomitant AIS and PE. Additionally, twelve articles (n = 15 subjects) fulfilled our literature review criteria for a total of 17 cases, including ours. Intravenous anticoagulation (70.5%) was the most frequent intervention targeting both disorders. Therapies such as intravenous thrombolysis (23.53% (n = 4)) and mechanical thrombectomy (23.53% (n = 4)) were specific in AIS. Catheter-directed thrombolysis (5.88%) was used for PE. Clinical outcomes were favorable (asymptomatic or mild disable symptoms) in 47.05% (N = 8) of patients, while 41.17% had poor outcomes (severe disable symptoms or death).

CONCLUSIONS

AIS and PE stand for a challenge when they present simultaneously. The evaluation of risks and benefits of therapies such as intravenous thrombolysis, mechanical thrombectomy, and catheter-directed-thrombolysis in the clinical context is essential. According to our review, the ischemic stroke burden guides systemic anticoagulation decisions over interventional procedures when the hemodynamic status remains unaffected.

Fibrinogen-mimicking, multiarm nanovesicles for human thrombus-specific delivery of tissue plasminogen activator and targeted thrombolytic therapy

Clinical use of tissue plasminogen activator (tPA) in thrombolytic therapy is limited by its short circulation time and hemorrhagic side effects. Inspired by fibrinogen binding to activated platelets, we report a fibrinogen-mimicking, multiarm nanovesicle for thrombus-specific tPA delivery and targeted thrombolysis. This biomimetic system is based on the lipid nanovesicle coated with polyethylene glycol (PEG) terminally conjugated with a cyclic RGD (cRGD) peptide. Our experiments with human blood demonstrated its highly selective binding to activated platelets and efficient tPA release at a thrombus site under both static and physiological flow conditions. Its clot dissolution time in a microfluidic system was comparable to that of free tPA. Furthermore, we report a purpose-built computational model capable of simulating targeted thrombolysis of the tPA-loaded nanovesicle and with a potential in predicting the dynamics of thrombolysis in physiologically realistic scenarios. This combined experimental and computational work presents a promising platform for development of thrombolytic nanomedicines.