Nanotechnology-based therapeutics: new hope for ischemic cerebral stroke intervention

Ischemic cerebral stroke is a leading cause of death and disability globally.At present,thrombolytics,such as recombinant tissue-type plasminogen activator,are the only effective treatment for acute stroke.However,usage of thrombolytics has a strict therapeutic window and cannot be applied to a number of patients.Despite the promising effects of some neuroprotectants in preclinical studies,they failed in clinical trials as a result of poor pharmacokinetic properties,particularly with regard to solubility and permeability across the blood-brain barrier(BBB).Approaches for delivering these drugs by nanotechnologies may overcome these pharmacokinetic deficits and enhance their neuroprotective effects.However,issues such as potential side effects and biosafety properties currently limit clinical application of these approaches.In this article,we reviewed recent progress of nanotechnology-based interventions for stroke treatment,and in particular,summarized novel materials applied to synthesize nanocarriers,encapsulation with neuroprotectants,and factors impacting nanodrug bioactivities to provide a theoretical basis for the development of anti-stroke drugs.

Neuroprotective Potential of Cerium Oxide Nanoparticles for Focal Cerebral Ischemic Stroke

During the previous years, with the emerging of nanotechnology, the enormous capabilities of nanoparticles have drawn great attention from researchers in terms of their potentials in various aspects of pharmacology. Cerium oxide nanoparticles（nanoceria）, considered as one of the most widely used nanomaterials, due to its tempting catalytic antioxidant properties, show a promising potential in diverse disorders, such as cerebral ischemic stroke（CIS）, cancer, neurodegenerative and inflammatory diseases. Overwhelming generation of reactive oxygen species（ROS） and reactive nitrogen species（RNS） during cerebral ischemia and reperfusion periods is known to aggravate brain damage via sophisticated cellular and molecular mechanisms, and therefore exploration of the antioxidant capacities of nanoceria becomes a new approach in reducing cerebral ischemic injury. Furthermore, utilizing nanoceria as a drug carrier might display the propensity to overcome limitations or inefficacy of other conceivable neuroprotectants and exhibit synergistic effects. In this review, we emphasize on the principle features of nanoceria and current researches concerning nanoceria as a potential therapeutic agent or carrier in improving the prognosis of CIS.

Effects of Integrins and Integrin αvβ3 Inhibitor on Angiogenesis in Cerebral Ischemic Stroke

Summary： Integrins such as αvβ3, α5β31 play a key role in angiogenesis regulation, invasion and metastasis, inflammation, wound healing, etc. The up-regulation of integrin αvβ3 after cerebral ischemic stroke can promote angiogenesis, which in turn improves functional recovery. In addition, the integrin αvβ3 inhibitor can block the blood-brain barrier （BBB） leakage induced by vascular endothelial growth factor （VEGF） and also can reduce inflammatory reaction, decrease the deposition of fibrinogen. Other studies showed that integrin αvβ3 is not essential in revascularization. Therefore, the effect of integrin αvβ3 in the whole process of brain function recovery merits further study.

Middle cerebral artery occlusion methods in rat versus mouse model of transient focal cerebral ischemic stroke

Experimental stroke research commonly employs focal cerebral ischemic rat models （Bederson et al., 1986a; Longa et al., 1989）. In human patients, ischemic stroke typically results from thrombotic or embolic occlusion of a major cerebral artery, usually the mid- dle cerebral artery （MCA）. Experimental focal cerebral ischemia models have been employed to mimic human stroke （Durukan and Tatlisumak, 2007）. Rodent models of focal cerebral ischemia that do not require craniotomy have been developed using intraluminal suture occlusion of the MCA （MCA occlusion, MCAO） （Rosamond et al., 2008）. Furthermore, mouse MCAO models have been wide- ly used and extended to genetic studies of cell death or recovery mechanisms （Liu and McCullough, 2011）. Genetically engineered mouse stroke models are particularly useful for evaluation of isch- emic pathophysiology and the design of new prophylactic, neuro- protective, and therapeutic agents and interventions （Armstead et al., 2010）. During the past two decades, MCAO surgical techniques have been developed that do not reveal surgical techniques for mouse MCAO model engineering. Therefore, we compared MCAO surgical methods in rats and mice.

Doppler examination and cerebral arterial stricture in patients with ischemic stroke

BACKGROUND: With the development of interventional therapy, it is necessary for evaluating cerebral vessels to instruct treatment and determine prognosis of patients with ischemic stroke; however, correlation of distribution of infarction focus and clinical symptoms with degrees of cerebrovascular stricture is still unclear. OBJECTIVE: To evaluate the characteristics of cerebral arterial stricture of patients with ischemic stroke with transcranial Doppler (TCD) and color duplex flow imaging (CDFI) and compare the correlation between distribution of cerebral infarction focus and clinical types with magnetic resonance imaging (MRI). DESIGN: Contrast observation. SETTING: Department of Neurology, the First Hospital of Jilin University. PARTICIPANTS: A total of 159 patients with ischemic stroke were selected from the Department of Neurology, the First Hospital of Jilin University from January to December 2005, including 106 males and 53 females aged from 27 to 88 years. Bases on diagnostic criteria of cerebrovascular disease established by Rao et al, clinical manifestations of all patients were evaluated with CT or nuclear magnetic resonance. All patients provided the confirmed consent. METHODS: The accepted patients received TCD and CDFI examination at 1 week after onset of ischemic stroke. Among them, 112 patients received cerebrovascular imaging examination simultaneously. MRI was used to check cerebral infarction focus and cerebrovascular stricture > 50% was regarded as the accepted vessels. In addition, DWI-T2 TCD (Germany) was used to check middle cerebral artery, and degrees of middle cerebral artery were classified into mild, moderate and severe stricture based on blood velocity (140 cm/s, 180 cm/s). Stroke was classified based on characteristics of infarction focus and clinical symptoms showed with MRI and correlation with degrees of cerebrovascular stricture was analyzed simultaneously. MAIN OUTCOME MEASURES: Correlation between the characteristics of ischemic stroke and clinical symptoms checked with TCD and CDFI. RESULTS: A total of 159 patients with ischemic stroke were involved in the final analysis; in addition, 112 cases received cerebrovascular imaging examination simultaneously. ① MRI results of 159 patients with cerebral artery occlusive disease (CAOD): There were 131 patients (82.3%) with cerebral infarction, 40 (25.2%) with transient ischemic attack and 4 (2.5%) with subclavian steal syndrome (SSS). ② Infarction types with MRI examination: There were 33 patients (20.8%) with solitary cerebral infarction and 98 (61.6%) with multiple-cerebral infarction. ③ Results of TCD, CDFI, MRI angiography, CT angiography and digital subtraction angiography (DSA): Among 112 patients, 181 lesion sites (61.8%) were located in cranium and 112 lesion sites were located out of cranium; especially, lesion site was mostly observed in stem of middle cerebral artery (31.2%) and watershed of basilar artery (7.2%) in cranium and the beginning site of internal carotid artery (21.4%) out of cranium. ④ Correlation of vascular stricture checking with TCD, MRI and clinical diagnosis: On one hand, MRI and clinical diagnosis demonstrated that 68 patients had a watershed infarction; meanwhile, TCD examination indicated that there were 3 patients with mild vascular stricture, 24 with moderate vascular stricture and 36 with severe vascular stricture. On the other hand, among 68 patients with non-watershed infarction, there were 27 patient with mild vascular stricture, 26 with moderate vascular stricture and 15 with severe vascular stricture. There were significant differences (χ2 =26.854, P =0.001). Clinical diagnosis indicated that 40 patients had transient ischemic attack and TCD examination demonstrated that there were 8 patient with mild vascular stricture, 12 with moderate vascular stricture and 20 with severe vascular stricture. There were significant differences as compared with 68 patients with watershed infarction (χ2 =21.258, P =0.001). ⑤ Correlation of vascular stricture checking with CDFI, MRI and clinical diagnosis: On one hand, among patients who were determined as watershed infarction with MRI and clinical diagnosis, CDFI examination indicated that there were 32 patients with mild vascular stricture at neck, 25 with moderate vascular stricture and 6 with severe vascular stricture. On the other hand, among patients with non-watershed infarction, there were 48 patient with mild vascular stricture, 18 with moderate vascular stricture and 2 with severe vascular stricture. There were significant differences (χ2 =6.018, P =0.019). Among patients with transient ischemic attack checking with clinical diagnosis, there were 23 patient with mild vascular stricture, 9 with moderate vascular stricture and 8 with severe vascular stricture. There were no significant differences as compared with patients with non-watershed infarction (χ2 =0.597, P =0.440). CONCLUSION: ① TCD and CDFI are effective marks to determine cerebral arterial stricture and hemodynamical changes. ② Infarction and transient ischemic attack at watershed are generally clinical phenotypes of CAOD patients and infarction at watershed is correlated with degrees of cerebrovascular stricture. ③ TCD, MRI and clinical analysis of stroke types are significant for instructing treatment and evaluate prognosis.

Inhibition of cerebral ischemia/reperfusion injuryinduced apoptosis:nicotiflorin and JAK2/STAT3 pathway

Nicotiflorin is a flavonoid extracted from Carthamus tinctorius.Previous studies have shown its cerebral protective effect,but the mechanism is undefined.In this study,we aimed to determine whether nicotiflorin protects against cerebral ischemia/reperfusion injury-induced apoptosis through the JAK2/STAT3 pathway.The cerebral ischemia/reperfusion injury model was established by middle cerebral artery occlusion/reperfusion.Nicotiflorin（10 mg/kg） was administered by tail vein injection.Cell apoptosis in the ischemic cerebral cortex was examined by hematoxylin-eosin staining and terminal deoxynucleotidyl transferase d UTP nick end labeling assay.Bcl-2 and Bax expression levels in ischemic cerebral cortex were examined by immunohistochemial staining.Additionally,p-JAK2,p-STAT3,Bcl-2,Bax,and caspase-3 levels in ischemic cerebral cortex were examined by western blot assay.Nicotiflorin altered the shape and structure of injured neurons,decreased the number of apoptotic cells,down-regulates expression of p-JAK2,p-STAT3,caspase-3,and Bax,decreased Bax immunoredactivity,and increased Bcl-2 protein expression and immunoreactivity.These results suggest that nicotiflorin protects against cerebral ischemia/reperfusion injury-induced apoptosis via the JAK2/STAT3 pathway.

Evaluation of the Curative Effect of "Xingnao Kaiqiao" Acupuncture Based on Brunnstrom Staging on Upper Limb and Hand Motor Function in the Recovery Period after Stroke

Objective: To observe the effects of Xingnao Kaiqiao acupuncture(醒脑开窍针) on the motor function of upper limb and hand in the recovery period after stroke. Methods: Seventy-six cases of hemiplegia patients with ischemic stroke were divided into the treatment group and the control group(n=38 in each). Based on the Brunnstrom's stage of Xingnao Kaiqiao acupuncture combined with rehabilitation training was used in the treatment group, and the control group was given rehabilitation training. FuglMeyer Assessment of the upper extremity(FMA-UE), Action Research Arm Test(ARAT) and Simple Test for Evaluating hand Function(STEF) were adopted separately to compare scores before treatment and 8 weeks after treatment. Results: The difference was not statistically significant in the two groups of patients for comparison of FMA-UE, ARAT and STEF scores before treatment(P>0.05). The difference was statistically significant in the two groups of score comparison of FMA-UE, ARAT and STEF after treatment(P<0.05). Conclusion: The Xingnao Kaiqiao acupuncture has its unique advantages in improving recovery of motor function of upper limb and hand in recovery period after stroke.

Danshen-Chuanxiongqin Injection attenuates cerebral ischemic stroke by inhibiting neuroinflammation via the TLR2/ TLR4-MyD88-NF-κB Pathway in tMCAO mice

Danshen-Chuanxiongqin Injection(DCI)is a commonly used traditional Chinese medicine for the treatment of cerebral ischemic stroke in China.However,its underlying mechanisms remain completely understood.The current study was designed to explore the protective mechanisms of DCI against cerebral ischemic stroke through integrating whole-transcriptome sequencing coupled with network pharmacology analysis.First,using a mouse model of cerebral ischemic stroke by transient middle cerebral artery occlusion(tMCAO),we found that DCI(4.10 mL·kg−1)significantly alleviated cerebral ischemic infarction,neurological deficits,and the pathological injury of hippocampal and cortical neurons in mice.Next,the whole-transcriptome sequencing was performed on brain tissues.The cerebral ischemia disease(CID)network was constructed by integrating transcriptome sequencing data and cerebrovascular disease-related genes.The results showed CID network was imbalanced due to tMCAO,but a recovery regulation was observed after DCI treatment.Pathway analysis of the key genes with recovery efficiency showed that the neuroinflammation signaling pathway was highly enriched,while the TLR2/TLR4-MyD88-NF-κB pathway was predicted to be affected.Consistently,the in vivo validation experiments confirmed that DCI exhibited protective effects against cerebral ischemic stroke by inhibiting neuroinflammation via the TLR2/TLR4-MyD88-NF-κB pathway.More interestingly,DCI markedly suppressed the neutrophils infiltrated into the brain parenchyma via the choroid plexus route and showed anti-neuroinflammation effects.In conclusion,our results provide dependable evidence that inhibiting neuroinflammation via the TLR2/TLR4-MyD88-NF-κB pathway is the main mechanism of DCI against cerebral ischemic stroke in mice.

The clinical and imaging features of 118 patients with spontaneous cerebral arterial dissections presenting with ischemic stroke

Objective To investigate the clinical and radiologic features of patients with spontaneous cerebral arterial dissections(CADs)presenting with ischemic stroke and to explore the effect of gender and age on those features.Methods Patients admitted to our stroke center diagnosed as ischemic stroke secondary to CADs from August 2008to April 2015 were prospectively registered.