Vascular endothelial growth factor in cerebral ischemia

Vascular endothelial growth factor (VEGF) is involved in many central nervous system disorders, including stroke, and confers neuroprotection in cerebral ischemia. In this Mini-Review, we examine in detail the in vitro and in vivo evidence for the role of VEGF in cerebral ischemia. VEGF is a therapeutic mediator for cerebral ischemia because of its angiogenic and neuroprotective effects. However, several studies indicate that the delivery route and the timing of VEGF delivery seem to determine the outcome of VEGF therapy after an ischemic insult. In the acute stage of cerebral ischemia, the effect of VEGF is considered controversial. Therefore, further work is necessary to identify a suitable therapeutic regime prior to phase II/III clinical trials. In addition, recent studies indicate that VEGF enhances neurogenesis after ischemia. Therefore, further investigation is necessary to clarify the exact role of VEGF in neurogenesis.     

兔大脑中动脉阻断所致局灶性脑缺血脑组织内皮抑素蛋白及mRNA表达增加

目的内皮抑素（endostatin）是强烈的抗血管再生因子。本文探讨大脑中动脉闭塞（middle cerebral artery occlusion,MCAO）致局灶性脑缺血后脑组织内皮抑素蛋白及mRNA基因表达的变化,同时检测缺血脑组织血管内皮生长因子（vascular endothelial growth factor,VEGV0的含量。方法24只新西兰白兔随机分为正常对照组（n=5）、假手术组（n=4）、缺血2小时组（n=5）、缺血24小时组（n=5）及缺血48小时组（n=5）共5组。酶联免疫吸附试验测定VEGF含量,免疫组化分析内皮抑素蛋白变化,原位杂交检测内皮抑素mRNA表达。结果与对照组相比,MCAO局灶性脑缺血后内皮抑素蛋白和mRNA表达均明显增加,至少分别增加了50％（P〈0．01）和70％（P〈0．05）,同时缺血脑组织VEGF含量也明显增加,至少增加了270％。结论缺血导致脑组织内皮抑素表达增加,且内皮抑素的增加与缺血后脑组织VEGF变化无相关性,但可能抑制脑缺血后的血管再生,从而加重脑缺血损伤。     

石杉碱甲、尼莫地平对脑缺血鼠学习记忆障碍与血管内皮生长因子、Caspase-3表达的影响

目的:对脑缺血大鼠采用尼莫地平与石杉碱甲进行药物干预治疗,观察治疗后不同药物组血管内皮生长因子(VEGF)、caspase-3表达水平与学习记忆改善程度。方法:采用免疫组化和Y迷宫检测脑缺血鼠学习记忆功能的变化及VEGF、caspase-3在缺血区的表达。结果:各治疗组VEGF、caspase-3在海马区、大脑皮质、基底节区表达均显著低于脑缺血对照组(A组)P<0.01,尤以海马、大脑皮质区较显著。其中石杉碱甲加尼莫地平干预组(B组)VEGF、caspase-3细胞阳性表达的降低和学习记忆功能的改善,明显好于A、C、D组,P<0.01。结论:石杉碱甲加尼莫地平治疗组与其他药物治疗组比,能有效改善VEGF、caspase-3表达水平和提高学习记忆的能力,为认知障碍早期的治疗提供依据。     

血管内皮生长因子和碱性成纤维细胞生长因子在缺血预处理大鼠局灶性脑缺血再灌注区域的表达

背景：脑缺血预处理可增加碱性成纤维细胞生长因子的表达,可能导致脑缺血耐受的产生。大鼠大脑中动脉缺血再灌注给予血管内皮生长因子能够起到神经保护作用。 目的：观察缺血预处理对缺血再灌注大鼠血管内皮生长因子和碱性成纤维细胞生长因子表达的影响。 方法：将SD大鼠随机分为缺血预处理组、模型组和假手术组。缺血预处理及模型组线栓法阻塞大脑中动脉制备脑缺血模型。预处理组在脑缺血-再灌注前3 d用插入尼龙线阻塞大脑中动脉,缺血2 h后再灌注22 h。模型组第一次手术将线栓前推5 mm,不阻断血流,其他同预处理组。假手术组仅插入尼龙线不阻塞大脑中动脉。用苏木精-伊红染色法观察3组间神经细胞变化。用抗生物素-生物素-过氧化物酶复合物法检测各组血管内皮生长因子和碱性成纤维细胞生长因子蛋白的表达。分别比较3组神经功能评分、光镜下脑缺血再灌注区神经细胞形态、血管内皮生长因子和碱性成纤维细胞生长因子的表达。 结果与结论：与模型组比较,预处理组神经功能评分明显低于模型组(P < 0.01)。光镜下观察结果显示,与模型组比较,预处理组缺血面积及缺血程度均减轻,血管内皮生长因子和碱性成纤维细胞生长因子表达均明显升高(P < 0.05)。结果提示缺血预处理可能通过增强血管内皮生长因子和碱性成纤维细胞生长因子而对缺血再灌注大鼠神经细胞起保护作用。     

复方丹参片对慢性脑缺血大鼠脑内VEGF表达的影响

目的研究中药复方丹参对慢性脑缺血大鼠脑内VEGF表达的影响,探讨复方丹参治疗慢性脑缺血的作用机制。方法采用永久性双侧大鼠颈总动脉结扎术(2VO)制备大鼠慢性脑缺血模型。术后每日给予复方丹参0.75mg/kg灌胃,对照组给予同等量蒸馏水,1次/d,共8周。用免疫组化法观察2VO大鼠脑内VEGF表达。结果药物组大鼠脑内VEGF表达明显增强。结论复方丹参片可显著增加2VO大鼠脑内VEGF的表达,提示复方丹参片可促进VEGF在大鼠脑内表达,促进慢性脑缺血的代偿修复。     

兔大脑中动脉阻断所致局灶性脑缺血脑组织内皮抑素蛋白及mRNA表达增加(英文)

目的内皮抑素(endostatin)是强烈的抗血管再生因子。本文探讨大脑中动脉闭塞 (middle cerebral artery occlusion, MCAO)致局灶性脑缺血后脑组织内皮抑素蛋白及mRNA基因表达的变化,同时检测缺血脑组织血管内皮生长因子(vascular endothelial growth factor,VEGF)的含量。方法24只新西兰白兔随机分为正常对照组(n=5)、假手术组(n=4)、缺血2小时组(n=5)、缺血24小时组 (n=5)及缺血48小时组(n=5)共5组。酶联免疫吸附试验测定VEGF含量,免疫组化分析内皮抑素蛋白变化,原位杂交检测内皮抑素mRNA表达。结果与对照组相比,MCAO局灶性脑缺血后内皮抑素蛋白和mRNA表达均明显增加,至少分别增加了50%(P<0.01)和70%(P<0.05),同时缺血脑组织VEGF含量也明显增加,至少增加了270%。结论缺血导致脑组织内皮抑素表达增加,且内皮抑素的增加与缺血后脑组织VEGF变化无相关性,但可能抑制脑缺血后的血管再生,从而加重脑缺血损伤。     

实验性局灶性脑缺血不同脑区VEGF、VEGFR-1、2表达及意义

目的 通过探索血管内皮生长因子及其受体在局灶性脑缺血中的表达，进而探求血管内皮生长因子在局灶性脑缺血中的作用。方法 应用左侧颈总动脉结扎加缺氧诱导的方法，建立SD大鼠永久大脑中动脉闭塞模型，应用免疫组化方法检测血管内皮生长因子及其受体(VEGF、VEGFR-1、2)的表达，同时观察局灶性脑缺血后血管型成情况。结果 VEGF及VEGFR-1、2在局灶性脑缺血后6h表达增强，24h达高峰，在1周、2周恢复到对照水平。VEGF主要在缺血半影区(IP)神经元、胶质细胞及血管内皮细胞表达；VEGFR-1、2主要在缺血半影区血管内皮细胞表达。在缺血后48h半影区周边出现血管增生，1周后达高峰。结论 在局灶性脑缺血早期VEGF及VEGFR-1、2在神经细胞、胶质细胞、血管内皮细胞等均有表达，可促进缺血半影区的血管增生，对改善缺血半影区血供有重要作用。     

补阳还五汤干预局灶性脑缺血模型大鼠VEGF表达和血管新生

中风是一种因缺血导致脑细胞死亡常见的脑血管疾病。缺血周围区血管新生可增强组织血液供应,是一个中风治疗的潜在方法。补阳还五汤是中医治疗中风的传统名方。在本研究中,我们观察补阳还五汤对脑缺血后大鼠脑内血管生成和促血管再生因子血管内皮生长因子基因和蛋白表达的影响。用大脑中动脉闭塞MCAO）法诱导成年雄性大鼠脑缺血模型,大鼠随机分为正常组,假手术组,缺血组和缺血+补阳还五汤组4组（每组每时间点15只动物）,在缺血2小后时按每公斤体重5克生药量/天给予补阳还五汤,连续14天。测定缺血后1,3,7和14天微血管密度和血管内皮生长因子基因和蛋白的表达。研究发现补阳还五汤能显著增强脑缺血后血管新生,增加血管内皮生长因子基因和蛋白质表达,较缺血组差异有显著性（p<0.05）。结果表明补阳还五汤能增强大鼠脑缺血后脑内血管新生,提高促血管再生因子血管内皮生长因子基因和蛋白水平,这可能是补阳还五汤治疗中风的潜在机制。本文首次探讨了补阳还五汤对脑缺血后脑内血管新生和促血管再生因子血管内皮生长因子基因和蛋白的影响,为其临床应用提供了实验依据。     

骨髓间充质干细胞旁分泌作用与脑缺血后的细胞凋亡*

背景：骨髓间充质干细胞移植治疗脑缺血的机制之一是骨髓间充质干细胞的旁分泌作用,而目前对于这一机制的研究报道较少。 目的：观察骨髓间充质干细胞旁分泌作用对脑缺血后细胞凋亡的抑制作用并探索相关机制。 方法：体外培养大鼠骨髓间充质干细胞,建立大鼠大脑中动脉缺血模型。24只SD大鼠随机数字表法分为4组,每组6只。细胞移植给药组：大鼠纹状体内移植骨髓间充质干细胞后给予ERK1/2抑制剂U0126;非移植给药组：注射等量的PBS后给予U0126;细胞移植对照组：移植骨髓间充质干细胞后给予溶剂对照;非移植对照组：注射等量的PBS后给予溶剂对照。7 d后通过Western blot检测血管内皮细胞生长因子、磷酸化ERK1/2蛋白的表达;TUNEL染色检测梗死区周围及皮质区细胞凋亡情况。 结果与结论：细胞移植组较非移植组大鼠纹状体内血管内皮细胞生长因子蛋白的表达明显增高,磷酸化ERK1/2表达增强,细胞凋亡数明显减少;经U0126处理后,血管内皮细胞生长因子的表达没有变化,而随着磷酸化ERK1/2的表达受到抑制,细胞凋亡数明显增高。提示骨髓间充质干细胞在大脑纹状体内可以旁分泌血管内皮细胞生长因子,并通过激活ERK1/2抑制了脑梗死区细胞的凋亡。     

Angiopoietin-2 is vasoprotective in the acute phase of cerebral ischemia

Most forms of cerebral ischemia are characterized by damage to the entire neurovascular unit, which leads to an increase in the permeability of the blood–brain barrier (BBB). In response to permanent focal cerebral ischemia in mice, we detected an early concomitant increase in the expression of the vascular endothelial growth factor (VEGF), a key inducer of vascular leakage and pathological blood vessel growth, and of angiopoietin-2 (Ang2), which is closely associated with VEGF in vascular remodeling. Thus, the aim of this study was to evaluate the role of Ang2 alone, or in combination with VEGF, in the acute phase of cerebral ischemia. The effect of these angiogenic factors on the ischemic lesion volume was evaluated by magnetic resonance imaging. We observed that timely administration of VEGF exacerbates ischemic damage. In contrast, Ang2 decreases the ischemic volume and this beneficial effect is maintained in the presence of VEGF. This investigation reports, for the first time, a protective role of Ang2 following cerebral ischemia, an action associated with a reduced BBB permeability. We propose that Ang2 represents a pertinent molecular target for the treatment of cerebral ischemia since acute brain damage may be limited by a pharmacological protection of the vascular compartment.     

低氧特异性重组腺相关病毒VEGF165的构建与表达

目的构建VEGF165低氧启动rAAV载体,用于缺血性脑血管病的治疗.方法通过分子生物学的方法,构建VEGF165低氧启动rAAV载体,采用磷酸钙和氯仿-PEG8000/NaCl-氯仿法构建低氧启动rAAV病毒.通过体内外低氧诱导,验证VEGF165低氧启动rAAV对低氧的特异性.结果体内外实验证实,VEGF165低氧启动rAAV仅在低氧诱导后表达具有生物活性的VEGF蛋白,对低氧具有特异性.结论VEGF165低氧启动rAAV构建成功,可望用于缺血性疾病的基因治疗.     

VEGF-overexpressing transgenic mice show enhanced post-ischemic neurogenesis and neuromigration

New neurons are generated continuously in the subventricular zone and dentate gyrus of the adult brain. Neuropathologic processes, including cerebral ischemia, can enhance neurogenesis, as can growth factors and other physiologic stimuli. Vascular endothelial growth factor (VEGF) is an angiogenic and neuroprotective growth factor that can promote neurogenesis, but it is unknown whether VEGF can enhance migration of newborn neurons toward sites of ischemic injury, where they might be able to replace neurons that undergo ischemic death. In the present study we produced permanent focal cerebral ischemia in transgenic (Tg) mice that overexpress VEGF. Cell proliferation and neurogenesis were assessed with bromodeoxyuridine (Brdu) labeling and immunostaining for cell type-specific markers. In VEGF-Tg mice, brains examined 7-28 days after cerebral ischemia showed markedly increased subventricular zone (SVZ) neurogenesis, chains of neuroblasts extending from the SVZ to the peri-infarct cortex, and an increase in the number of newly generated cortical neurons at 14-28 days after ischemia. In concert with these effects, VEGF overexpression reduced infarct volume and improved postischemic motor function. These findings provide evidence that VEGF increases SVZ neurogenesis and neuromigration, consistent with a possible role in repair. Our data suggest that in addition to its neuroprotective effects, which are associated with improved outcome in the acute phase after cerebral ischemia, VEGF enhances postischemic neurogenesis, which could provide a therapeutic target for more chronic brain repair.     

VEGF治疗脑缺血再灌注损伤的分子机制研究

目的 通过检测血管内皮生长因子（VEGF）治疗兔脑缺血再灌注损伤的有关分子表达情况,探讨其分子机制.方法 采用兔大脑中动脉阻塞（MCAO）2h再灌注72h模型,在再灌注即刻,应用微量进样器将VEGF立体定向导入梗死灶周,于再灌注72h断头取脑,应用免疫组化方法检测缺血半暗带区caspase-3和细胞外信号调节激酶1（estracellular signal-regulated kinase,ERK1）的表达情况.结果 VEGF治疗后缺血半暗带区caspase-3和ERK1表达明显减低.结论 VEGF可能通过抑制caspase-3和ERK1表达发挥治疗作用.     

VEGF Ameliorates Cognitive Impairment in In Vivo and In Vitro Ischemia via Improving Neuronal Viability and Function

Vascular endothelial growth factor (VEGF) has recently been proved to be a potential therapeutic drug in ischemic disorders depending on the dose, route and time of administration, especially in focal cerebral ischemia. Whether VEGF could exert protection in a long-term total cerebral ischemic model is still uncertain, and the cellular mechanism has not been clarified so far. In order to answer the above issue, an experiment was performed in non-invasively giving exogenous VEGF to a total cerebral ischemic model rats and examining their spatial cognitive function by performing Morris water maze and long-term potential test. Moreover, we performed in vitro experiment to explore the cellular mechanism of VEGF protection effect. In an in vitro ischemia model oxygen–glucose deprivation (OGD), whole-cell patch-clamp recording was employed to examine neuronal function. Additionally, hematoxylin–eosin and propidium iodide staining were applied in vivo and in vitro in the neuropathological and viability study, separately. Our results showed that intranasal administration of VEGF could improve the cognitive function, synaptic plasticity and damaged hippocampal neurons in a global cerebral ischemia model. In addition, VEGF could retain the membrane potential, neuronal excitability and spontaneous excitatory postsynaptic currents in the early stage of ischemia, which further demonstrated that there was an acute effect of VEGF in OGD-induced pyramidal neurons. Simultaneously, it was also found that the death of CA1 pyramidal neuronal was significantly reduced by VEGF, but there was no similar effect in VEGF coexists with SU5416 group. These results indicated that VEGF could ameliorate cognitive impairment and synaptic plasticity via improving neuronal viability and function through acting on VEGFR-2.     

缺血再灌注对鼠脑血管内皮生长因子表达的影响

目的 了解血管内皮生长因子（VEGF）在一过性全脑缺血再灌注鼠脑表达的动态变化。方法 采用Pulisnelli改良法四血管堵塞全脑缺血再灌注模型,用免疫组织化学方法观察了全缺血15min再灌注2－14d时,VEGF表达的动肪变化。结果 全脑缺血15min再灌注6h VEGF即可在大脑皮层,纹状体及丘脑等区域的血管内皮细胞表达,1d达高峰,一直持续到缺血后再灌注3d,结论 脑缺血后再灌注可上调VEGF在大脑皮质,纹状体及丘脑等区域内皮细胞的表达,VEGF可能通过促进血管内皮细胞生长对缺血性神经元损伤起一定的作用。     

局灶性缺血预处理对脑缺血大鼠血管内皮生长因子表达及血管形成的影响

目的：探讨血管内皮生长因子（VEGF）在脑缺血耐受中的作用及其与血管形成的关系。方法：Wistar大鼠线栓法阻塞大脑中动脉建立局灶性缺血预处理模型,并进行神经功能评分。随机分为假手术（对照组）、非缺血预处理（NIP）组和缺血预处理（IP）组,NIP和IP组再根据不同时间窗随机分成5个亚组。分别在缺血预处理后1、3、7、14和21 d进行再次缺血2 h再灌注22 h,然后取脑检测：TTC染色测定脑梗死体积,计数微血管密度,免疫组化检测CD34和VEGF蛋白表达,原位杂交法检测VEGF mRNA表达。结果：①组间比较：IP 1、3和7 d亚组脑梗死体积较NIP组明显减小（P〈0.01）,其神经行为缺损评分也明显降低（P〈0.05）;IP 3和7 d亚组脑微血管密度明显增高（P〈0.05）;IP 1、3和7 d亚组VEGF蛋白及mRNA表达明显增高（P〈0.05,P〈0.01）。②组内比较：IP 7 d亚组微血管在缺血灶周边区分布最为密集,脑微血管密度明显高于同组内其他亚组（P〈0.05）;IP 3和7 d亚组VEGF蛋白表达明显增高,VEGF mRNA表达在IP 1 d即开始升高,高峰出现在IP 3 d,持续至7 d。结论：缺血预处理诱导了脑缺血耐受,缺血预处理诱导的VEGF表达增加以及血管形成在脑缺血耐受中发挥重要作用。     

选择素对脑缺血再灌注损伤作用的研究进展

选择素(selectin)是血管黏附分子大家族中的一类成员,根据表达部位不同可分为3类:E-selectin,L-selectin,P-selectin。选择素参与介导脑缺血再灌注损伤中的炎症反应,导致缺血区脑组织损伤。本文就选择素的分子结构和对脑缺血再灌注损伤的作用研究现状进行探讨。     

Inhibition of VEGF signaling pathway attenuates hemorrhage after tPA treatment

An angiogenic factor, vascular endothelial growth factor (VEGF), might be associated with the blood–brain barrier (BBB) disruption after focal cerebral ischemia; however, it remains unknown whether hemorrhagic transformation (HT) after tissue plasminogen activator (tPA) treatment is related to the activation of VEGF signaling pathway in BBB. Here, we hypothesized that inhibition of VEGF signaling pathway can attenuate HT after tPA treatment. Rats subjected to thromboembolic focal cerebral ischemia were assigned to a permanent ischemia group and groups treated with tPA at 1 or 4 hours after ischemia. Anti-VEGF neutralizing antibody or control antibody was administered simultaneously with tPA. At 24 hours after ischemia, we evaluated the effects of the antibody on the VEGF expression, matrix metalloproteinase-9 (MMP-9) activation, degradation of BBB components, and HT. Delayed tPA treatment at 4 hours after ischemia promoted expression of VEGF in BBB, MMP-9 activation, degradation of BBB components, and HT. Compared with tPA and control antibody, combination treatment with tPA and the anti-VEGF neutralizing antibody significantly attenuated VEGF expression in BBB, MMP-9 activation, degradation of BBB components, and HT. It also improved motor outcome and mortality. Inhibition of VEGF signaling pathway may be a promising therapeutic strategy for attenuating HT after tPA treatment.     

步长脑心通胶囊对大鼠脑缺血再灌注损伤的神经保护作用

目的研究步长脑心通胶囊对脑缺血再灌注(IR)损伤的神经保护作用。方法采用Longas法制备大鼠脑IR模型,分为IR组、步长脑心通组;再灌注后2h开始给药,依照IR的持续时间不同又分为1d、3d、7d、10d及15d共5组。各时相点取材,用HE染色和电镜观察脑部组织学改变,用干湿重法进行脑含水量测定;免疫组化染色检测脑组织血管内皮生长因子(VEGF)的表达,并使用多媒体彩色病理图像分析系统进行定量分析。结果与IR组比较,步长脑心通组脑组织中皱缩或肿胀神经元数目少,胞浆肿胀较轻,胶质细胞肿胀不明显,血管周围间隙水肿和渗出较轻;脑含水量及VEGF的表达差异具有显著性(均P<0.05)。结论步长脑心通胶囊可减少IR后脑含水量并增强VEGF表达,从而起到神经保护作用。     

血管内皮生长因子在高原脑水肿形成中作用的实验研究

目的:探讨血管内皮生长因子(VEGF)在高原脑水肿形成中的作用。方法:建立大鼠模拟高原模型,应用脑干湿重比率法定量脑水肿情况、应用荧光素钠透过率测定BBB通透性、应用实时荧光定量RT-PCR法检测脑组织VEGF mRNA含量以及应用蛋白印迹法半定量脑组织VEGF含量。结果:大鼠在高原24 h后脑组织含水率明显增高(P<0.05),荧光素钠透过率显著增加(P<0.01);VEGF mRNA转录及其表达显著增高(P<0.001)。结论:VEGF表达在高原脑水肿形成中起重要作用。