Recanalization and Reperfusion Therapies of Acute Ischemic Stroke: What have We Learned, What are the Major Research Questions, and Where are We Headed?

Functional Outcome and Mortality Predictors in Patients with Cerebral Ischemic Infarction After Decompressive Craniectomy: Cross-Sectional Study

OBJECTIVE

Surgeons commonly perform Decompressive craniectomy (DC) to manage patients with cerebral ischemic infarction. However, there are conflicting data on the long-term functional outcomes following DC. Therefore, this study aims to determine the functional outcome of patients with cerebral ischemic infarction after DC.

METHODS

This prospective and retrospective cross-sectional study included 148 patients with cerebral ischemic infarction who underwent DC at Ghaem Hospital, Mashhad, Iran, from March 2011 to March 2021. The Modified Rankin Scale (mRS) assesses disability in these patients and determines the recovery and degree of long-term functional outcomes. Demographic and clinical data were extracted and recorded in a researcher-made questionnaire.

RESULTS

In summary, the follow-up revealed a survival rate of 39.2% among patients with ischemic stroke. The comparison of the mean infarct volume in patients with various mRS scores showed that the mean infarct volume was significantly higher in patients with unfavorable functional outcomes, based on mRS scores at discharge (P = 0.05), 3 months mRS (P < 0.01), and mRS score at final follow-up (P = 0.01). Final mortality was higher in patients with higher mRS scores at discharge, after 3 months, and final follow-up (P < 0.01). Older age and infarction volume can predict mRS and mortality in patients with ischemic stroke (P < 0.01).

CONCLUSIONS

The present study showed that mortality and mRS scores at various times are associated with infarction volume and older age in patients with ischemic stroke.

rtPA-loaded fucoidan polymer microbubbles for the targeted treatment of stroke

Systemic injection of thrombolytic drugs is the gold standard treatment for non-invasive blood clot resolution. The most serious risks associated with the intravenous injection of tissue plasminogen activator-like proteins are the bleeding complication and the dose related neurotoxicity. Indeed, the drug has to be injected in high concentrations due to its short half-life, the presence of its natural blood inhibitor (PAI-1) and the fast hepatic clearance (0.9 mg/kg in humans, 10 mg/kg in mouse models). Overall, there is a serious need for a dose-reduced targeted treatment to overcome these issues. We present in this article a new acoustic cavitation-based method for polymer MBs synthesis, three times faster than current hydrodynamic-cavitation method. The generated MBs are ultrasound responsive, stable and biocompatible. Their functionalization enabled the efficient and targeted treatment of stroke, without side effects. The stabilizing shell of the MBs is composed of Poly-Isobutyl Cyanoacrylate (PIBCA), copolymerized with fucoidan. Widely studied for its targeting properties, fucoidan exhibit a nanomolar affinity for activated endothelium and activated platelets (P-selectins). Secondly, the thrombolytic agent (rtPA) was loaded onto microbubbles (MBs) with a simple adsorption protocol. Hence, the present study validated the in vivo efficiency of rtPA-loaded Fuco MBs to be over 50 % more efficient than regular free rtPA injection for stroke resolution. In addition, the relative injected rtPA grafted onto targeting MBs was 1/10th of the standard effective dose (1 mg/kg in mouse). As a result, no hemorrhagic event, BBB leakage nor unexpected tissue distribution were observed.

Improving treatment for acute ischemic stroke—Clot busting innovation in the pipeline

Acute ischemic stroke is a consequence of disrupted blood flow to the brain, caused by thrombosis—the pathological formation of occlusive clots within blood vessels, which can embolize distally to downstream tissues and microvasculature. The highest priority of stroke treatment is the rapid removal of occlusive clots and restoration of tissue perfusion. Intravenous thrombolysis is the pharmacological standard-of-care for the dissolution of blood clots, wherein thrombolytic drugs are administered to restore vessel patency. While the introduction of recombinant tissue-plasminogen activator (rtPA) in 1996 demonstrated the benefit of acute thrombolysis for clot removal, this was countered by severe limitations in terms of patient eligibility, lytic efficacy, rethrombosis and safety implications. Development of safer and efficacious treatment strategies to improve clot lysis has not significantly progressed over many decades, due to the challenge of maintaining the necessary efficacy-safety balance for these therapies. As such, rtPA has remained the sole approved acute therapeutic for ischemic stroke for over 25 years. Attempts to improve thrombolysis with coadministration of adjunct antithrombotics has demonstrated benefit in coronary vessels, but remain contraindicated for stroke, given all currently approved antithrombotics adversely impact hemostasis, causing bleeding. This Perspective provides a brief history of stroke drug development, as well as an overview of several groups of emerging drugs which have the potential to improve thrombolytic strategies in the future. These include inhibitors of the platelet receptor glycoprotein VI and the signaling enzyme PI3-Kinase, novel anticoagulants derived from hematophagous creatures, and proteolysis-targeting chimeras.

Circular RNA cerebellar degeneration-related protein 1 antisense RNA (Circ-CDR1as) downregulation induced by dexmedetomidine treatment protects hippocampal neurons against hypoxia/reoxygenation injury through the microRNA-28-3p (miR-28-3p)/tumor necrosis factor receptor-associated factor-3 (TRAF3) axis

Cerebral ischemia/reperfusion (CI/R) injury results in serious brain tissue damage, thereby leading to long-term disability and mortality. It has been reported that dexmedetomidine (DEX) exerted neuroprotective effects in CI/R injury. Herein, we intended to investigate whether and how circular RNA (circRNA) cerebellar degeneration-related protein 1 antisense RNA (circ-CDR1as) was involved in the DEX-mediated protection on hippocampal neurons. In our work, the mouse hippocampal neuronal cells (HT-22) were used to construct a hypoxia/reperfusion (H/R) model for CI/R injury. Cell proliferation and apoptosis were evaluated by CCK-8 and flow cytometry. Gene expressions were detected by RT-qPCR. Levels of pro-inflammatory cytokines (TNF-α, IL-6, and IL-1β) were measured by ELISA. The association between miR-28-3p and circ-CDR1as or TRAF3 was verified by dual-luciferase assay. The results indicated that DEX alleviated HT-22 cell dysfunction induced by H/R treatment. In addition, circ-CDR1as was downregulated after DEX treatment and reversed the effects of DEX on the proliferation, apoptosis, and inflammatory responses of H/R-treated HT-22 cells. Circ-CDR1as positively regulated TRAF3 expression via interaction with miR-28-3p in HT-22 cells. Circ-CDR1as aggravated H/R-treated HT-22 cell dysfunction through targeting miR-28-3p. Furthermore, TRAF3 inhibition partly abolished the effect of circ-CDR1as overexpression on cellular activities of H/R-treated HT-22 cells. To sum up, our findings, for the first time, demonstrated that DEX exerted neuroprotective effects on hippocampal neurons against H/R treatment via the circ-CDR1as/miR-28-3p/TRAF3 regulatory network, providing novel therapeutic targets for DEX administration in CI/R treatment.

Medicarpin Protects Cerebral Microvascular Endothelial Cells Against Oxygen-Glucose Deprivation/Reoxygenation-Induced Injury via the PI3K/Akt/FoxO Pathway: A Study of Network Pharmacology Analysis and Experimental Validation

Medicarpin, a pterocarpan class of naturally occurring phytoestrogen possesses various biological functions. However, the effect of medicarpin on oxygen-glucose deprivation-reoxygenation (OGD/R)-induced injury in human cerebral microvascular endothelial cells (HCMECs) remains largely unknown. Target genes of medicarpin were predicted from PharmMapper. Target genes of ischemic stroke were predicted from public databases GeneCards and DisGeNET. Kyoto Encyclopedia of Genes and Genomes pathway enrichment of the intersecting targets was analyzed via DAVID 6.8. Cell viability was evaluated using CCK-8 assay. Malondialdehyde content, superoxide dismutase activity, and glutathione level were detected using corresponding commercially available kits. Cell death was assessed by TUNEL assays. Expression of protein kinase B (Akt), phosphorylated-Akt, forkhead box protein O1, phosphorylated-FoxO1, FoxO3a, and phosphorylated-FoxO3a (p-FoxO3a) was detected by western blot analysis. The intersecting targets of medicarpin and ischemic stroke were significantly enriched in phosphatidylinositol 3-kinase (PI3K)/Akt and FoxO pathways. Medicarpina attenuated OGD/R-evoked viability inhibition, oxidative stress, and cell death in HCMECs. Additionally, medicarpin activated the PI3K/Akt and FoxO pathways in OGD/R-induced HCMECs. Inhibition of PI3K/Akt pathway abrogated the neuroprotective effect of medicarpin on OGD/R-induced injury and activation of FoxO pathway in HCMECs. In conclusion, medicarpin suppressed OGD/R-induced injury in HCMECs by activating PI3K/Akt/FoxO pathway.

Efficacy and safety of Cerebrolysin after futile recanalisation therapy in patients with severe stroke

INTRODUCTION

Golden standard of acute stroke treatment is recanalisation therapy. However, opening the occluded blood vessel sometimes does not show the expected clinical result or leads to haemorrhagic complications. As neuroinflammation and neurotoxicity play an important role in the pathophysiology of stroke, neuroprotective agents might preserve brain tissue after futile recanalisation.

PATIENTS AND METHODS

After recanalisation therapy and not later than 24 h after symptoms onset, patients with initial NIHSS of ≥ 8 were assigned to the investigational and control group. The investigational group received intravenous Cerebrolysin as add-on therapy. The primary objective was to assess the clinical efficacy of Cerebrolysin. The secondary objective was to investigate its effect on haemorrhagic transition and to confirm its safety profile.

RESULTS

Baseline characteristics of patients showed no significant differences between the two groups. No difference could be detected between the two groups in the mRS scale though the Cerebrolysin group showed descriptive superiority over the control group. We found a statistically significant difference considering haemorrhagic transition and mortality rate in favour of the Cerebrolysin group.

DISCUSSION

The multimodal neurotrophic agent Cerebrolysin holds promise to impact on the late consequences of a reperfusion syndrome. Its influence on reducing neuroinflammation, promoting neuronal cell viability and neurogenesis as well as the stabilising effect on the blood-brain barrier suggests a protective effect on the neurovascular unit even when no recanalisation occurs. We confirmed the excellent safety profile of Cerebrolysin.

CONCLUSION

Cerebrolysin as add-on therapy might be beneficial and safe for patients with acute stroke in terms of lowering risk for haemorrhagic complications after recanalisation therapy.

Targeting the Autonomic Nervous System for Risk Stratification, Outcome Prediction and Neuromodulation in Ischemic Stroke

Ischemic stroke is a worldwide major cause of mortality and disability and has high costs in terms of health-related quality of life and expectancy as well as of social healthcare resources. In recent years, starting from the bidirectional relationship between autonomic nervous system (ANS) dysfunction and acute ischemic stroke (AIS), researchers have identified prognostic factors for risk stratification, prognosis of mid-term outcomes and response to recanalization therapy. In particular, the evaluation of the ANS function through the analysis of heart rate variability (HRV) appears to be a promising non-invasive and reliable tool for the management of patients with AIS. Furthermore, preclinical molecular studies on the pathophysiological mechanisms underlying the onset and progression of stroke damage have shown an extensive overlap with the activity of the vagus nerve. Evidence from the application of vagus nerve stimulation (VNS) on animal models of AIS and on patients with chronic ischemic stroke has highlighted the surprising therapeutic possibilities of neuromodulation. Preclinical molecular studies highlighted that the neuroprotective action of VNS results from anti-inflammatory, antioxidant and antiapoptotic mechanisms mediated by α7 nicotinic acetylcholine receptor. Given the proven safety of non-invasive VNS in the subacute phase, the ease of its use and its possible beneficial effect in hemorrhagic stroke as well, human studies with transcutaneous VNS should be less challenging than protocols that involve invasive VNS and could be the proof of concept that neuromodulation represents the very first therapeutic approach in the ultra-early management of stroke.

Inhibition of LncRNA MALAT1 Attenuates Cerebral Ischemic Reperfusion Injury via Regulating AQP4 Expression

Stroke is one of the leading causes of mortality and disability worldwide. Long noncoding RNAs (lncRNAs) including MALAT1 have been shown to have critical roles in cerebral ischemia reperfusion injury (CIRI). However, the underlying mechanism of MALAT1 in CIRI has not been elucidated. The present study aimed to investigate the function and potential regulatory mechanism of MALAT1 in cerebral ischemic reperfusion injury. We established the middle cerebral artery occlusion (MCAO) model and oxygen-glucose deprivation/reoxygenation (OGD/RX) model in vivo and in vitro, and then Cell Counting Kit-8 (CCK-8), RT-qPCR, flow cytometry analysis, lactate dehydrogenase (LDH) analysis, and 2,3,5-triphenyltetrazolium chloride (TTC) staining were used to examine cell viability, MALAT1, aquaporin-4 (AQP4) expression, LDH release, and infarct volume, respectively. The level of AQP4 was remarkably upregulated in CIRI 24 h/48 h or OGD/RX 24 h/48 h compared with the sham group. Knockdown of AQP4 could alleviate OGD/RX-induced injury through enhancing cell viability and reducing LDH release and the rate of apoptotic cells. Furthermore, we found that MALAT1 was also increased in OGD/RX 24 h/48 h and silencing of MALAT1 could decrease AQP4. Inhibition of MALAT1 could also protect OGD/RX-induced injury, while the protective effect of MALAT1 siRNA on cerebral ischemic reperfusion was disappeared after transfection with AQP4 plasmid, indicating that MALAT1 may play a protective role in brain stroke through regulating AQP4. Taken together, our study provides evidence that MALAT1 is involved in ischemic stroke by inhibiting AQP4. Therefore, MALAT1 may serve as a potential target for therapeutic intervention in ischemic brain injury.

Blockade of HCN2 Channels Provides Neuroprotection Against Ischemic Injury via Accelerating Autophagic Degradation in Hippocampal Neurons

In the central nervous system, hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are essential to maintain normal neuronal function. Recent studies have shown that HCN channels may be involved in the pathological process of ischemic brain injury, but the mechanisms remain unclear. Autophagy is activated in cerebral ischemia, but its role in cell death/survival remains controversial. In this study, our results showed that the HCN channel blocker ZD7288 remarkably decreased the percentage of apoptotic neurons and corrected the excessive autophagy induced by oxygen-glucose deprivation followed by reperfusion (OGD/R) in hippocampal HT22 neurons. Furthermore, in the OGD/R group, p-mTOR, p-ULK1 (Ser757), and p62 were significantly decreased, while p-ULK1 (Ser317), atg5, and beclin1 were remarkably increased. ZD7288 did not change the expression of p-ULK1 (Ser757), ULK1 (Ser317), p62, Beclin1, and atg5, which are involved in regulating autophagosome formation. Besides, we found that OGD/R induced a significant increase in Cathepsin D expression, but not LAMP-1. Treatment with ZD7288 at 10 μmol/L in the OGD/R group did not change the expression of cathepsin D and LAMP-1. However, chloroquine (CQ), which decreases autophagosome-lysosome fusion, eliminated the correction of excessive autophagy and neuroprotection by ZD7288. Besides, shRNA knockdown of HCN2 channels significantly reduced the accumulation of LC3-II and increased neuron survival in the OGD/R and transient global cerebral ischemia (TGCI) models, and CQ also eliminated the effects of HCN2-shRNA. Furthermore, we found that the percentage of LC3-positive puncta that co-localized with LAMP-1-positive lysosomes decreased in Con-shRNA-transfected HT22 neurons exposed to OGD/R or CQ. In HCN2-shRNA-transfected HT22 neurons, the percentage of LC3-positive puncta that co-localized with LAMP-1-positive lysosomes increased under OGD/R; however, the percentage was significantly decreased by the addition of CQ to HCN2-shRNA-transfected HT22 neurons. The present results demonstrated that blockade of HCN2 channels provides neuroprotection against OGD/R and TGCI by accelerating autophagic degradation attributable to the promotion of autophagosome and lysosome fusion.

Lysophosphatidic Acid Reduces Microregional Oxygen Supply/Consumption Balance after Cerebral Ischemia-Reperfusion

BACKGROUND

Lysophosphatidic acid (LPA) is a small phospholipid-signaling molecule, which can alter responses to stress in the central nervous system.

OBJECTIVE

We hypothesized that exogenous LPA would increase the size of infarct and reduce microregional O2 supply/consumption balance after cerebral ischemia-reperfusion.

METHODS

This was tested in isoflurane-anesthetized rats with middle cerebral artery blockade for 1 h and reperfusion for 2 h with or without LPA (1 mg/kg, at 30, 60, and 90 min after reperfusion). Regional cerebral blood flow was determined using a C14-iodoantipyrine autoradiographic technique. Regional small-vessel (20-60 µm in diameter) arterial and venous oxygen saturations were determined microspectrophotometrically.

RESULTS

There were no significant hemodynamic or arterial blood gas differences between groups. The control ischemic-reperfused cortex had a similar O2 consumption to the contralateral cortex. However, microregional O2 supply/consumption balance was significantly reduced in the ischemic-reperfused cortex with many areas of low O2 saturation (43 of 80 veins with O2 saturation below 50%). LPA did not significantly alter cerebral blood flow, but it did significantly increase O2 extraction and consumption of the ischemic-reperfused region. It also significantly increased the number of small veins with low O2 saturations in the reperfused region (76 of 80 veins with O2 saturation below 50%). This was associated with a significantly increased cortical infarct size after LPA administration (11.4 ± 0.5% control vs. 16.4 ± 0.6% LPA).

CONCLUSION

This suggests that LPA reduces cell survival and that it is associated with an increase in the number of small microregions with reduced local oxygen balance after cerebral ischemia-reperfusion.

Futile Recanalization With Poor Clinical Outcome Is Associated With Increased Edema Volume After Ischemic Stroke

PURPOSE

Futile recanalization with poor clinical outcome after endovascular treatment of acute ischemic stroke is poorly understood. Recently, vessel recanalization has been associated with reduced ischemic brain edema in patients with good clinical outcome. As edema volume (EV) may be quantified in computed tomography (CT), we hypothesized that higher EV after revascularization predicts futile recanalization with poor outcome.

METHODS

In this observational study, 67 ischemic stroke patients with M1 middle cerebral artery occlusion fulfilled all inclusion criteria and were analyzed. All patients received successful endovascular recanalization (thrombolysis in cerebral infarction scale 2b/3) and subsequent follow-up CT 24 hours later. Edema volume within the infarct lesion was calculated in follow-up CT applying lesion water uptake quantification and was used to predict clinical outcome (Modified Rankin Scale [mRS] after 90 days) compared with infarct volume.

RESULTS

The median EV after thrombectomy was 1.6 mL (interquartile range, 0.2-4.2 mL) in patients with mRS 0 to 4 and 8.6 mL (interquartile range, 2.0-49.8 mL) in patients with mRS 5 to 6 (P = 0.0008). In regression analysis, an EV increase of 1 mL was associated with an 8.0% increased likelihood of poor outcome (95% confidence interval, 2.8%-15.4%; P = 0.008). Based on univariate receiver operating characteristic curve analysis, absolute EV over 4.2 mL predicted poor outcome (mRS 5-6) with good discriminative power (area under curve, 0.74; 95% confidence interval, 0.62-0.84; specificity, 77%; sensitivity, 68%). In comparison, the area under curve for infarct volume was 0.68.

CONCLUSIONS

Elevated EV after endovascular thrombectomy was associated with poor clinical outcome and may indicate futile recanalization.

Acute remote ischemic preconditioning alleviates free radical injury and inflammatory response in cerebral ischemia/reperfusion rats

Remote ischemic preconditioning (IPreC) is an effective strategy to defend against cerebral ischemia/reperfusion (IR) injury; however, its mechanisms remain to be elucidated. The aim of the present study was to investigate the effect of IPreC on brain tissue following cerebral ischemia, as well as the underlying mechanisms. Adult male Sprague-Dawley rats were treated with IPreC for 72 h prior to the induction of transient cerebral ischemia and reperfusion. The results demonstrated that IPreC reduced the area of cerebral infarction in the IR rats by 2,3,5-triphenyl-tetrazolium chloride staining. In addition, cell apoptosis was markedly suppressed by IPreC with an increased expression of B-cell lymphoma 2 (Bcl-2)/Bcl-2-associatd X protein using Terminal deoxynucleotidyl-transferase-mediated dUTP nick end labeling assay and western blot analysis. IR induced a decrease in the level of superoxide dismutase, and IPreC significantly suppressed increased levels of malondialdehyde, lactate dehydrogenase and nitric oxide. The expression of CD11b and CD18 was markedly inhibited by IpreC unsing flow cytometry. Furthermore, IPreC markedly decreased the release of pro-inflammatory factors interleukin (IL)-6 and IL-1β, and enhanced the level of anti-inflammatory factors (IL-10 and IL-1 receptor antagonist) by ELISA assay. Finally, IPreC reduced the levels of transforming growth factor-β-activated kinase 1, phosphorylated-P65/P65, and tumor necrosis factor-α, indicating that the nuclear factor-κB pathway was involved in IPreC-mediated protection against cerebral ischemia. Taken together, the results suggested that IPreC decreased ischemic brain injury through alleviating free radical injury and the inflammatory response in cerebral IR rats.

Effect of β-patchoulene on cerebral ischemia-reperfusion injury and the TLR4/NF-κB signaling pathway

β-patchoulene (β-PAE), an active constituent of the Pogostemon cablin, is well known for its anti-inflammatory and antioxidative functions in various diseases. However, little is known about the impact of β-PAE on the cerebral ischemia-reperfusion (I/R) injury. The current study aimed to determine the neuroprotective effect of β-PAE and the underlying mechanisms on cerebral I/R injury. Following pretreatment with β-PAE (10 mg/kg body weight) by tail intravenous injection for 1 h, Sprague-Dawley rats were subjected to middle cerebral artery occlusion for 2 h and reperfusion for 24 h. The results indicated that pretreatment with β-PAE could diminish the infarct volume, decrease the brain water content, reduce the neurological deficit score and restore the mitochondrial membrane potential, compared with the untreated I/R injury group. Furthermore, cell apoptosis was markedly suppressed by β-PAE, and this effect was associated with the decreased apoptosis regulator BAX/apoptosis regulator Bcl-2 expression ratio and caspase-3 activity. In addition, β-PAE significantly inhibited the release of proinflammatory factors, including tumor necrosis factor-α, interleukin (IL)-1β and IL-6. Superoxide generation and malondialdehyde levels were reduced while the levels of glutathione peroxidase and superoxide dismutase were elevated following treatment with β-PAE, indicating the antioxidative role of β-PAE in cerebral I/R injury. Furthermore, the Toll-like receptor 4 (TLR4)/nuclear factor-κB (NF-κB) signaling pathway was inhibited by β-PAE, as demonstrated by the decreased TLR4 expression and nuclear translocation of p65, and increased IκBα level. Taken together, the results suggested that β-PAE may exhibit a neuroprotective effect on cerebral I/R injury in rats through inactivating the TLR4/NF-κB signaling pathway.

Role of Decompressive Craniectomy in Ischemic Stroke

Ischemic stroke is one of the leading causes for death and disability worldwide. In patients with large space-occupying infarction, the subsequent edema complicated by transtentorial herniation poses a lethal threat. Especially in patients with malignant middle cerebral artery infarction, brain swelling secondary to the vessel occlusion is associated with high mortality. By decompressive craniectomy, a significant proportion of the skull is surgically removed, allowing the ischemic tissue to shift through the surgical defect rather than to the unaffected regions of the brain, thus avoiding secondary damage due to increased intracranial pressure. Several studies have shown that decompressive craniectomy reduces the mortality rate in patients with malignant cerebral artery infarction. However, this is done for the cost of a higher proportion of patients who survive with severe disability. In this review, we will describe the clinical and radiological features of malignant middle cerebral artery infarction and the role of decompressive craniectomy and additional therapies in this condition. We will also discuss large cerebellar stroke and the possibilities of suboccipital craniectomy.

Stroke, cerebrovascular diseases and vascular cognitive impairment in Africa

With increased numbers of older people a higher burden of neurological disorders worldwide is predicted. Stroke and other cerebrovascular diseases do not necessarily present with different phenotypes in Africa but their incidence is rising in tandem with the demographic change in the population. Age remains the strongest irreversible risk factor for stroke and cognitive impairment. Modifiable factors relating to vascular disease risk, diet, lifestyle, physical activity and psychosocial status play a key role in shaping the current spate of stroke related diseases in Africa. Hypertension is the strongest modifiable risk factor for stroke but is also likely associated with co-inheritance of genetic traits among Africans. Somewhat different from high-income countries, strokes attributed to cerebral small vessel disease (SVD) are higher >30% among sub-Saharan Africans. Raised blood pressure may explain most of the incidence of SVD-related strokes but there are likely other contributing factors including dyslipidaemia and diabetes in some sectors of Africa. However, atherosclerotic and cardioembolic diseases combined also appear to be common subtypes as causes of strokes. Significant proportions of cerebrovascular diseases are ascribed to various forms of infectious disease including complications of human immunodeficiency virus. Cerebral SVD leads to several clinical manifestations including gait disturbance, autonomic dysfunction and depression. Pathological processes are characterized by arteriolosclerosis, lacunar infarcts, perivascular spaces, microinfarcts and diffuse white matter changes, which can now all be detected on neuroimaging. Except for isolated cases of cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy or CADASIL, hereditary arteriopathies have so far not been reported in Africa. Prevalence estimates of vascular dementia (2-3%), delayed dementia after stroke (10-20%) and vascular cognitive impairment (30-40%) do not appear to be vastly different from those in other parts of the world. However, given the current demographic transition in both urban and rural settings these figures will likely rise. Wider application of neuroimaging modalities and implementation of stroke care in Africa will enable better estimates of SVD and other subtypes of stroke. Stroke survivors with SVD type pathology are likely to have low mortality and therefore portend increased incidence of dementia.

Clarion call for histopathological clot analysis in "cryptogenic" ischemic stroke: implications for diagnosis and treatment

Diagnosis, treatment, and secondary management of cryptogenic stroke patients pose a formidable challenge. The scenario is further complicated in patients with native and prosthetic valvular heart disease. We present a case study of a 36‐year‐old man who received intravenous thrombolysis (IV‐tPA) and endovascular thrombectomy (EVT) for presumed “cryptogenic” complete middle cerebral artery infarction who made a surprisingly excellent clinical recovery despite poor baseline and postintervention neuroimaging. Retrospective gram stain of his clot confirmed a diagnosis of infective endocarditis. This raises an important issue regarding need for more routine histopathological analysis of clot retrieved after EVT in “cryptogenic” stroke patients particularly those with valvular heart disease.

Vectorized nanodelivery systems for ischemic stroke: a concept and a need

Neurological diseases of diverse aetiologies have significant effects on the quality of life of patients. The limited self-repairing capacity of the brain is considered to be the origin of the irreversible and progressive nature of many neurological diseases. Therefore, neuroprotection is an important goal shared by many clinical neurologists and neuroscientists. In this review, we discuss the main obstacles that have prevented the implementation of experimental neuroprotective strategies in humans and propose alternative avenues for the use of neuroprotection as a feasible therapeutic approach. Special attention is devoted to nanotechnology, which is a new approach for developing highly specific and localized biomedical solutions for the study of the multiple mechanisms involved in stroke. Nanotechnology is contributing to personalized neuroprotection by allowing us to identify mechanisms, determine optimal therapeutic windows, and protect patients from brain damage. In summary, multiple aspects of these new players in biomedicine should be considered in future in vivo and in vitro studies with the aim of improving their applicability to clinical studies.

Effects of Nigella sativa Extract on Markers of Cerebral Angiogenesis after Global Ischemia of Brain in Rats

BACKGROUND

Reduction of permanent or transient cerebral blood flow may lead to some structural and functional changes of the brain, causing high mortality and morbidity. The aim of this experimental study was to investigate the effects of hydroalcoholic extract of Nigella sativa (NS) on markers of cerebral angiogenesis in rats induced by global brain ischemia.

METHODS

Thirty-two male Wistar rats (250 ± 20 g) were randomly divided into 4 groups: group 1, control group receiving only normal saline; group 2, sham group undergoing surgery and stroke induction without treatment; and groups 3 and 4 treated with 10 and 20 mg/kg NS, respectively, after induction of stroke. Global ischemia was induced by ligation of the right carotid artery for 20 minutes.

RESULTS

According to the results of this study, brain edema and infarct volume were significantly decreased in the group treated with 20 mg/kg NS compared with the group treated with 10 mg/kg NS (P < .05). Global ischemia caused a significant reduction in gene expression of vasoactive endothelial growth factor (VEGF) and hypoxia-inducible factor (HIF) in the sham group compared with the control group (P < .05), but NS groups, in led to a significant increase in gene expression of VEGF and HIF compared with the sham group (P < .05). In addition, the activity level of matrix metallopeptidase-9 was decreased among NS groups compared with the control group (P < .05).

CONCLUSIONS

Application of NS extract among rats with brain ischemia is associated with increase of VEGF and HIF as angiogenic markers and inhibition of matrix metallopeptidase-9 activities.

Ischemic Stroke

Each year, more than 795,000 people in the United States suffer a stroke and by 2030, it is estimated that 4% of the U.S. population will have had a stroke. Home healthcare clinicians will be increasingly called upon to assist stroke survivors and their caregivers adjust to disability and assist the survivor during their reintegration into the community. Therapeutic modalities are changing with advanced technology. Great strides are being made in the treatment of acute stroke; particularly endovascular interventions. More patients are surviving the acute stroke event and therefore will need to learn how to live with various degrees of disability. It is important for home healthcare clinicians to understand the process from acute event to medical stabilization, and from rehabilitation to long-term adaptation.

Cerebral collateral circulation in experimental ischemic stroke

Cerebral collateral circulation is a subsidiary vascular network, which is dynamically recruited after arterial occlusion, and represents a powerful determinant of ischemic stroke outcome. Although several methods may be used for assessing cerebral collaterals in the acute phase of ischemic stroke in humans and rodents, they are generally underutilized. Experimental stroke models may play a unique role in understanding the adaptive response of cerebral collaterals during ischemia and their potential for therapeutic modulation. The systematic assessment of collateral perfusion in experimental stroke models may be used as a “stratification factor” in multiple regression analysis of neuroprotection studies, in order to control the within-group variability. Exploring the modulatory mechanisms of cerebral collaterals in stroke models may promote the translational development of therapeutic strategies for increasing collateral flow and directly compare them in term of efficacy, safety and feasibility. Collateral therapeutics may have a role in the hyperacute (even pre-hospital) phase of ischemic stroke, prior to recanalization therapies.

A novel mechanism of neuroprotection: Blood glutamate grabber

Glutamate excitotoxicity is a primary contributor of ischemic neuronal death and other cellular components of the neurovascular unit. Several strategies have been developed against glutamate excitotoxicity, however none of them have not shown positive results in the clinical practice so far. Nowadays, the concept of blood/brain glutamate grabbing or scavenging is well recognized as a novel and attractive protective strategy to reduce the excitotoxic effect of excess extracellular glutamate that accumulates in the brain following an ischemic stroke. The main advantage of this novel therapeutic strategy is that it occurs in the blood circulation and therefore does not affect the normal brain neurophysiology, as it has been described for other drug treatments used against glutamate excitotoxicity. In this work we report all experimental data from the beginning of our studies, focused on stroke pathology, and we describe new findings about the potential application of this therapy. Future clinical trials will allow to know the real efficacy of this novel therapeutic strategy in stroke patients.

Effects of rapamycin on cerebral oxygen supply and consumption during reperfusion after cerebral ischemia

Activation of the mammalian target of rapamycin (mTOR) leads to cell growth and survival. We tested the hypothesis that inhibition of mTOR would increase infarct size and decrease microregional O2 supply/consumption balance after cerebral ischemia-reperfusion. This was tested in isoflurane-anesthetized rats with middle cerebral artery blockade for 1h and reperfusion for 2h with and without rapamycin (20mg/kg once daily for two days prior to ischemia). Regional cerebral blood flow was determined using a C(14)-iodoantipyrine autoradiographic technique. Regional small-vessel arterial and venous oxygen saturations were determined microspectrophotometrically. The control ischemic-reperfused cortex had a similar blood flow and O2 consumption to the contralateral cortex. However, microregional O2 supply/consumption balance was significantly reduced in the ischemic-reperfused cortex. Rapamycin significantly increased cerebral O2 consumption and further reduced O2 supply/consumption balance in the reperfused area. This was associated with an increased cortical infarct size (13.5±0.8% control vs. 21.5±0.9% rapamycin). We also found that ischemia-reperfusion increased AKT and S6K1 phosphorylation, while rapamycin decreased this phosphorylation in both the control and ischemic-reperfused cortex. This suggests that mTOR is important for not only cell survival, but also for the control of oxygen balance after cerebral ischemia-reperfusion.

A vascular perspective on neuronal migration

During CNS development and adult neurogenesis, immature neurons travel from the germinal zones towards their final destination using cellular substrates for their migration. Classically, radial glia and neuronal axons have been shown to act as physical scaffolds to support neuroblast locomotion in processes known as gliophilic and neurophilic migration, respectively (Hatten, 1999; Marin and Rubenstein, 2003; Rakic, 2003). In adulthood, long distance neuronal migration occurs in a glial-independent manner since radial glia cells differentiate into astrocytes after birth. A series of studies highlight a novel mode of neuronal migration that uses blood vessels as scaffolds, the so-called vasophilic migration. This migration mode allows neuroblast navigation in physiological and also pathological conditions, such as neuronal precursor migration after ischemic stroke or cerebral invasion of glioma tumor cells. Here we review the current knowledge about how vessels pave the path for migrating neurons and how trophic factors derived by glio-vascular structures guide neuronal migration both during physiological as well as pathological processes.

Study of Protein Expression in Peri-Infarct Tissue after Cerebral Ischemia

In this work, we report our study of protein expression in rat peri-infarct tissue, 48 h after the induction of permanent focal cerebral ischemia. Two proteomic approaches, gel electrophoresis with mass spectrometry and combined fractional diagonal chromatography (COFRADIC), were performed using tissue samples from the periphery of the induced cerebral ischemic lesions, using tissue from the contra-lateral hemisphere as a control. Several protein spots (3408) were identified by gel electrophoresis, and 11 showed significant differences in expression between peri-infarct and contra-lateral tissues (at least 3-fold, p < 0.05). Using COFRADIC, 5412 proteins were identified, with 72 showing a difference in expression. Apart from blood-related proteins (such as serum albumin), both techniques showed that the 70 kDa family of heat shock proteins were highly expressed in the peri-infarct tissue. Further studies by 1D and 2D western blotting and immunohistochemistry revealed that only one member of this family (the inducible form, HSP72 or HSP70i) is specifically expressed by the peri-infarct tissue, while the majority of this family (the constitutive form, HSC70 or HSP70c) is expressed in the whole brain. Our data support that HSP72 is a suitable biomarker of peri-infarct tissue in the ischemic brain.