划痕损伤对大鼠大脑皮层微血管内皮细胞NF-κB表达及继发性死亡的影响

目的  通过体外培养SD大鼠大脑皮层微血管内皮细胞并制作划痕损伤模型,观察划痕损伤对脑微血管内皮细胞NF-κB表达及其自噬、凋亡和坏死的影响。方法  体外培养SD大鼠大脑皮层微血管内皮细胞并制作划痕损伤模型,应用NF-κB抑制剂吡咯醛二硫氨基甲酸（PDTC）干预划痕损伤脑微血管内皮细胞。随机分为对照组、单纯损伤组、损伤+抑制组,在不同时间点（损伤后1、6、12、24及48 h）分别应用免疫荧光细胞化学法测定磷酸化NF-κB p65蛋白的表达,Annexin V/PI染色法检测凋亡、坏死,Western blot检测自噬蛋白LC3Ⅱ表达情况。对照组为无划痕损伤的脑微血管内皮细胞。结果  脑微血管内皮细胞划痕损伤后NF-κB蛋白表达于伤后1 h开始表达增强,于24 h达高峰,与对照组比较差异有统计学意义（P <0.05）。凋亡、坏死及自噬各指标均随时间推移有不同程度升高,与对照组比较差异有统计学意义（P <0.05）。而经PDTC处理后上述变化均受不同程度的抑制,与单纯损伤组相比差异有统计学意义（P <0.05）。结论  划痕损伤后可激活脑微血管内皮细胞NF-κB表达,同时可引起脑微血管内皮细胞的自噬、凋亡和坏死。

     

大鼠脑微血管内皮细胞与星形胶质细胞共培养血脑屏障体外模型的建立

[目的]建立大鼠脑微血管内皮细胞与星形胶质细胞共培养血脑屏障体外模型。[方法]采用原代培养脑微血管内皮细胞与星形胶质细胞共培养方法建立血脑屏障体外模型。[结果]星形胶质细胞与脑微血管内皮细胞共培养可提高血脑屏障特异性酶——γ-谷胺酰胺转肽酶、碱性磷酸酶的表达,提高脑微血管内皮细胞跨细胞间电阻。[结论]成功建立脑微血管内皮细胞与星形胶质细胞共培养血脑屏障体外模型,而且较单层内皮细胞模型更接近在体状态。     

NF-κB subunits are differentially distributed in cells of lumbar dorsal root ganglia in naïve and diabetic rats

Mesenchymal stem cells (MSCs) hold much promise for cell therapy for neurological diseases such as cerebral ischemia and Parkinson's disease. Intravenously administered MSCs accumulate in lesions within the brain parenchyma, but little is known of the details of MSC transmigration across the blood-brain barrier (BBB). To study MSC transmigration across the BBB, we developed an in vitro culture system consisting of rat brain microvascular endothelial cells (BMECs) and bone marrow-derived MSCs using Transwell or Millicell culture inserts. Using this system, we first investigated the influence of the number of MSCs added to the upper chamber on BMEC barrier integrity. The addition of MSCs at a density of 1.5 × 10⁵ cells/cm² led to disruption of the BMEC monolayer structure and decreased barrier function as measured by the transendothelial electrical resistance (TEER). When applied at a density of 1.5 × 10⁴ cells/cm², neither remarkable disruption of the BMEC monolayers nor a significant decrease in TEER was observed until at least 12 h. After cultivation for 24 h under this condition, MSCs were found in the subendothelial space or beneath the insert membrane, suggesting that MSCs transmigrate across BMEC monolayers. Time-lapse imaging revealed that MSCs transmigrated across the BMEC monolayers through transiently formed intercellular gaps between the BMECs. These results show that our in vitro culture system consisting of BMECs and MSCs is useful for investigating the molecular and cellular mechanisms underlying MSC transmigration across the BBB.     

大鼠脑微血管内皮细胞与星形胶质细胞共培养血脑屏障体外模型的建立

【目的】建立大鼠脑微血管内皮细胞与星形胶质细胞共培养血脑屏障体外模型。【方法】采用原代培养脑微血管内皮细胞与星形胶质细胞共培养方法建立血脑屏障体外模型。【结果】星形胶质细胞与脑微血管内皮细胞共培养可提高血脑屏障特异性酶——γ-谷胺酰胺转肽酶、碱性磷酸酶的表达，提高脑微血管内皮细胞跨细胞间电阻。【结论】成功建立脑微血管内皮细胞与星形胶质细胞共培养血脑屏障体外模型，而且较单层内皮细胞模型更接近在体状态。     

Involvement of IbeA in meningitic Escherichia coli K1-induced polymorphonuclear leukocyte transmigration across brain endothelial cells

Transmigration of neutrophil [polymorphonuclear neutrophil (PMN)] across the blood-brain barrier (BBB) is a critical event in the pathogenesis of bacterial meningitis. We have shown that IbeA is able to induce meningitic Escherichia coli invasion of brain microvascular endothelial cells (BMECs), which constitutes the BBB. In this report, we provide evidence that IbeA and its receptor, vimentin, play a key role in E. coli-induced PMN transmigration across BMEC. In vitro and in vivo studies indicated that the ibeA-deletion mutant ZD1 was significantly less active in stimulating PMN transmigration than the parent strain E44. ZD1 was fully complemented by the ibeA gene and its product. E. coli-induced PMN transmigration was markedly inhibited by withaferin A, a dual inhibitor of vimentin and proteasome. These cellular effects were significantly stimulated and blocked by overexpression of vimentin and its head domain deletion mutant in human BMEC, respectively. Our studies further demonstrated that IbeA-induced PMN migration was blocked by bortezomib, a proteasomal inhibitor and correlated with upregulation of endothelial ICAM-1 and CD44 expression through proteasomal regulation of NFκB activity. Taken together, our data suggested that IbeA and vimentin contribute to E. coli K1-stimulated PMN transendothelial migration that is correlated with upregulation of adhesion molecule expression at the BBB.     

Transport of saquinavir across human brain-microvascular endothelial cells by poly(lactide-co-glycolide) nanoparticles with surface poly-(γ-glutamic acid)

Poly(lactide-co-glycolide) (PLGA) nanoparticles (NPs) with surface poly-(γ-glutamic acid) (γ-PGA) were applied to enhance the transport of saquinavir (SQV) across the blood-brain barrier (BBB). PLGA NPs encapsulated SQV and grafted with γ-PGA to form drug carriers (γ-PGA/SQV-PLGA NPs) for crossing through a monolayer of human brain-microvascular endothelial cells (HBMECs) regulated with human astrocytes. The results revealed that a lower molecular weight of γ-PGA yielded a higher grafting efficiency of γ-PGA on PLGA NPs. In addition, γ-PGA with a low molecular weight accelerated the dissolution of SQV from γ-PGA/SQV-PLGA NPs. A higher grafting efficiency (more didecyl dimethylammonium bromide) and a lower molecular weight of γ-PGA increased the permeability of SQV across the BBB, in general. When the grafting efficiency was 85.2% at 6 kDa of γ-PGA, γ-PGA/SQV-PLGA NPs reached about 6 times the permeability of free SQV (the maximal permeability). γ-PGA could also promote the endocytosis of NPs and expression of ornithine decarboxylase by HBMECs. γ-PGA/SQV-PLGA NPs are efficacious nanoparticulate carriers in delivering antiretroviral drug across the BBB.     

Comparative gene expression profiles of ABC transporters in brain microvessel endothelial cells and brain in five species including human

While P-glycoprotein (PGP, ABCB1) is known to play an important role in drug exclusion at the blood brain barrier (BBB), less is known about the contribution of other members in the ATP-binding cassette (ABC) transporter family to BBB drug efflux, or whether these transporters are expressed differently in humans and in mammalian species of pharmacological interest. We used quantitative real-time PCR to determine mRNA expression levels for the majority of ABC family members in brain and in isolated brain microvessel endothelial capillary cells (BMEC) from human, rat, mouse, pig and cow. We confirmed BBB expression of several well-characterized ABC family members that are implicated in xenobiotic exclusion from the brain, including ABCB1 (PGP), ABCG2 (BCRP), ABCC1 (MRP1), ABCC4 (MRP4), and ABCC5 (MRP5). In addition, we detected high expression and enrichment in BMEC of several less well-characterized ABC transporters in one or more species, including ABCA2-4, ABCB4, ABCB6-8, ABCB10, ABCC3, ABCC6, ABCC10, and ABCE1. We also uncovered species differences in the expression of a number of transporters, including ABCG2 and ABCC4. This study identifies several additional ABC family members that may contribute to xenobiotic efflux at the human BBB, and compares the expression of a broad array of efflux transporters between human and four other species relevant to pharmacological research.     

Understanding the blood-brain barrier using gene and protein expression profiling technologies

The blood-brain barrier (BBB) contributes to the brain homeostasis by regulating the passage of endogenous and exogenous compounds. This function is in part due to well-known proteins such as tight junction proteins, plasma membrane transporters and metabolic barrier proteins. Over the last decade, genomics and proteomics have emerged as supplementary tools for BBB research. The development of genomic and proteomic technologies has provided several means to extend the BBB knowledge and to investigate additional routes for the bypass of this barrier. These profiling technologies have been used on BBB models to decipher the physiological characteristics and, under stress conditions, to understand the molecular mechanisms of brain diseases. In this review, we will report and discuss the genomic and proteomic studies recently carried out to enhance the understanding of BBB features.     

大鼠脑微血管内皮细胞的原代培养及其生物学行为初步探讨

本文旨在探讨建立稳定的大鼠原代脑微血管内皮细胞的培养方法,并对其血脑屏障特性进行初步研究。通过匀浆、葡聚糖高速梯度离心提取大鼠脑皮层微血管段,用胶原酶消化后,在37℃,5%CO2孵箱中进行原代及传代细胞培养,以跨内皮阻抗值分析其血脑屏障特性随传代次数的改变。结果证明:原代培养后7～10d沿微血管段生成单层"铺路石"样细胞,经VIII因子证实95%以上的培养细胞是血管内皮细胞,通过传代可以进一步纯化,得到稳定的脑微血管内皮细胞系,原代培养的脑微血管内皮细胞表现出很强的屏障特性,与内皮细胞株之间有显著差异,随着传代次数的增加脑微血管内皮细胞的跨内皮阻抗减弱。以上结果表明,采用匀浆、梯度离心、胶原酶消化是获取大鼠脑微血管内皮细胞稳定的方法,原代培养的脑微血管内皮细胞是研究血脑屏障的最佳技术手段。     

丹芪偏瘫胶囊中羚羊角用人工牛黄替代的体外研究

为研究丹芪偏瘫胶囊(DPC)及DPC去羚羊角人工牛黄翻倍(DPCBD)对神经再生和血管再生的作用,初步探讨人工牛黄替代羚羊角的可能性,进行了体外培养细胞实验。本实验分为空白血清对照组、模型组、DPC组(0.306 g·kg^-1·d^-1,以下相同)、丹芪偏瘫胶囊去羚羊角(DPCRA)组、DPCBD组。体外培养脑微血管内皮细胞(BMEC)、星形胶质细胞(astrocytes)以及神经干细胞(neural stem cells,NSC),并将3种细胞共培养,模拟神经血管单元,用微管相关蛋白Ⅲ(β-tubulinⅢ)抗体标记神经元,用胶质纤维酸性蛋白(GFAP)标记astrocytes。酶标仪法检测BMEC乳酸脱氢酶(LDH)含量,倒置相差显微镜观察BMEC管样结构形成,显微镜下计数与BMEC黏附的白细胞个数,免疫荧光法检测β-tubulinⅢ和GFAP阳性细胞比例以及RT-PCR法检测NGF,BDNF,VEGF和VEGFr-2 mRNA的表达水平。结果显示,与模型组相比,DPC和DPCBD均可减少LDH漏出;均可促进BMEC管样结构形成;均可抑制白细胞与BMEC黏附;均可增加β-tubulinⅢ阳性细胞分化比例(P<0.01),降低GFAP阳性细胞比例(P<0.01);均能在一定程度上增加共培养细胞NGF,BDNF,VEGF和VEGFr-2 mRNA的表达,其中对NGF和VEGF mRNA表达水平的影响具有显著性差异(P<0.05),且2组疗效相当。DPCRA组对各指标的影响明显不如DPCBD和DPC组。DPCBD与DPC对神经再生和血管再生的作用疗效相当,提示丹芪偏瘫胶囊中羚羊角可用人工牛黄进行替代。