脑血管内皮细胞Prmt5基因敲除导致小胶质细胞激活并影响血脑屏障完整性

目的：研究脑血管内皮细胞Prmt5基因敲除小鼠脑中小胶质细胞是否激活,及其对血脑屏障渗透性的影响。方法：通过免疫荧光和Western blot检测小鼠皮层、丘脑、小脑中小胶质细胞标志分子表达水平,探究脑血管内皮细胞Prmt5基因敲除小鼠脑中小胶质细胞是否激活,并通过实时定量PCR和Western blot检测不同脑区M1型(CD86、CD16、TNF-α)和M2型(Ym1、Arg1、IL-10)小胶质细胞标志物,考察激活小胶质细胞极化类型。利用集落刺激因子1受体(CSF1R)抑制剂PLX5622清除对照和Prmt5基因敲除小鼠脑中的小胶质细胞,通过实时定量PCR、免疫荧光检测小胶质细胞标志物表达水平,评价小胶质细胞耗竭效率;利用N-羟基磺酸基琥珀生物素(Sulfo-NHS-Biotin)染料灌注和示踪的方法评价耗竭小胶质细胞对脑血管内皮细胞Prmt5基因敲除小鼠血脑屏障完整性的影响。结果：脑血管内皮细胞Prmt5基因敲除导致小胶质细胞激活,小胶质细胞M1型标志物(CD16、CD86及TNF-α)及M2型标志物(Ym1、Arg1及IL-10)均表达上调。PLX5622处理导致小胶质细胞耗...     

LPS诱导海马星形胶质细胞活化与活化的星形胶质细胞对海马神经元的影响

探讨脂多糖(Lipopolysaccharide,LPS)对长时间存活大鼠海马内星形胶质细胞的反应以及对神经元的影响。方法:本实验用10只健康成年雄性SD大鼠,海马CA3区注射LPS 10μ1．7和14d后,尼氏染色观察神经元的变化,免疫组织化学染色结合图像分析方法观察海马CA3区注射部位胶质纤维酸性蛋白(glial fibrillary acidic protein GFAP)、的表达变化。结果:脂多糖可促进海马星形胶质细胞的活化,但并不能引起海马区神经元的损伤。结论:星形胶质细胞在脑损伤后的脑内炎症反应起了一定的作用,但并不能引起神经元的损伤。     

基于单细胞转录组的基因富集方法分析星形胶质细胞与阿尔茨海默病的关系*

目的:通过生物信息学方法分析阿尔茨海默病(Alzheimer disease, AD)中与星形胶质细胞相关的糖代谢通路,为揭示AD患者的星形胶质细胞在大脑中的糖代谢过程提供理论基础。方法:首先根据细胞特异性表达基因将AD患者和健康人脑组织单细胞转录组学测序结果进行降维分析,再根据星形胶质细胞不同亚型的基因表达特征进行细胞分群,对星形胶质细胞差异表达基因进行基因注释(Gene Ontology. GO)、信号通路分析(Kyoto Encyclopedia of Genes and Genomes, KEGG)以及基因集富集分析(Gene Set Enrichment Analysis, GSEA),采用转录调控网络分析与AD的星形胶质细胞相关的转录辅助因子。结果:所有细胞降维分析结果显示AD患者脑内星形胶质细胞和兴奋性神经元数量显著减少;星形胶质细胞降维分析结果显示其可以被进一步分为6个亚群,其中在AD患者中减少的星形胶质细胞主要为RASGEF1B⁺SLC26A3⁺亚群和NRGN⁺CALM1⁺亚群;GO分析结果显示AD患者与健康对照星形胶质细胞差异表达基因主要与轴突发生、神经元的迁移、胶质细胞分化、体内锌离子稳态、突触传递的正调控、血管运输有关。KEGG结果显示,上述差异基因主要与PI3K-Akt信号通路、AMPK信号通路、钙信号通路有关。GSEA分析结果显示,AD患者差异基因在糖酵解/糖异生通路中得到富集,其中丙酮酸激酶PKM、PFKL、ACSS1、乳酸脱氢酶LDHB在AD患者星形胶质细胞中下调。转录调控网络分析结果显示,星形胶质细胞中差异表达转录辅助因子有5个,其中PKM、SOX2、SOX9在AD患者星形胶质细胞中下调。SREBF1和BCL6在AD患者星形胶质细胞中上调。结论:AD患者脑内兴奋性神经元和星形胶质细胞数量降低,以及星形胶质细胞糖酵解相关基因下调。结合星形胶质细胞作为神经元的主要乳酸供应细胞,其数量减少和糖酵解能力减低提示星形胶质细胞供能不足可能是AD发生的机制之一。     

脊髓背角浅层Hes5+星形胶质细胞在机械痛敏中发挥“门控”作用

近年来,人们对星形胶质细胞的功能有了更多更深入的认识。2020年11月,日本九州大学Makoto Tsuda教授实验室发表了题为脊髓背角浅层星形胶质细胞在机械痛敏中发挥门控作用的研究论文,揭示星形胶质细胞在机械痛传递过程中发挥关键作用(Nat Neurosci,2020,23:1376~1387)。     

星形胶质细胞可以诱导内皮细胞系紧密连接的形成

为探索星形胶质细胞在血脑屏障内皮细胞紧密连接形成中的重要意义,通过内皮细胞系ECV304与星形胶质细胞体外接触共培养的方法,采用电镜及内皮细胞紧密连接的银染观察星形胶质细胞对内皮细胞系紧密连接的诱导作用。运用Millipore-ERS系统检测紧密连接的功能状况。结果发现,星形胶质细胞可以诱导内皮细胞系形成广泛而连续的紧密连接并产生较高的跨内皮阻抗(transendothelial electrical resistance,TER),于第10d可达321．3Ωcm^2。提示,星形胶质细胞可以诱导ECV304细胞产生紧密连接。同时,ECV304细胞与星形胶质细胞的体外共培养可以作为研究血脑屏障紧密连接结构与功能的一种可靠而简便的体外实验方法。     

缺血缺氧对体外培养星形胶质细胞细胞活化和细胞周期的影响

目的观察缺血缺氧损伤对星形胶质细胞细胞活化和细胞周期的影响。方法用流式细胞仪及BrdU掺入法检测缺血缺氧后不同时间点星形胶质细胞细胞周期变化和细胞的增殖活力;用荧光免疫细胞化学技术测定胶质细胞纤维酸性蛋白(GFAP)及细胞周期蛋白cyclinD1的表达水平。结果体外缺血缺氧损伤后星形胶质细胞S期较正常组明显增高,6h达高峰,BrdU掺入法显示损伤后6h星形胶质细胞的增殖活力最高,而随后S期细胞数目及细胞增殖活力都呈下降趋势。在缺血缺氧早期,GFAP阳性染色增强,6h最高;缺血缺氧12h后GFAP阳性染色变弱,而cyclinD1的表达在损伤后逐渐增加,在24h时达高峰。结论缺血缺氧损伤激活星形胶质细胞,使其进入新的细胞周期,出现细胞的增殖反应;cyclinD1参与了损伤后星形胶质细胞的修复和增殖;细胞周期事件与星形胶质细胞的增殖活化密切相关。     

MiR-144通过靶向抑制GRK5表达促进脊髓星形胶质细胞活化

已知miR-144与细胞活化和增殖有关,然而其具体分子机制尚不明确。本研究发现miR-144通过靶向GRK5促进脊髓星形胶质细胞的活化。运用real-time PCR检测脊髓损伤和正常大鼠的脊髓组织及其脊髓星形胶质细胞中miR-144的表达,发现与正常的组织和细胞相比,miR-144在脊髓损伤组织和星形胶质细胞中的表达水平显著降低;Western印迹检测到脊髓损伤大鼠的星形胶质细胞中GFAP蛋白的表达显著低于正常大鼠,而GRK5蛋白的表达高于正常大鼠;MTT分析结果显示转染miR-144可显著提高脊髓损伤大鼠的星形胶质细胞活性,但对细胞增殖无明显作用;酶活性试剂盒分析发现miR-144显著提高了SOD和GSH活性;生物学信息分析和萤光素酶报告基因检测结果显示miR-144能靶向结合GRK5,并下调GRK5的表达;MiR-144 mimic转染或miR-144 mimic与pcDNA-GRK5共转染脊髓损伤的星形胶质细胞,发现miR-144转染能通过激活NF-κB通路消除pcDNA-GRK5引起的细胞活化抑制。综上所述,miR-144通过靶定结合癌基因GRK5来促进脊髓星形胶质细胞细胞的活化。     

星形胶质细胞的生物学功能

人类大脑由两类细胞组成:一类是神经元,另一类是神经胶质细胞。神经胶质细胞的数量约为神经元的10倍,但其作用长期以来一直被认为仅限于在神经元之间充当填充物,填满大脑中的剩余空间,同时为神经元提供营养。但近年来认识到神经胶质细胞的主要成员星形胶质细胞能够感知外界刺激,它的反应选择性甚至高于相邻神经元。神经元的反应活动很多都要经过星形胶质细胞的介导才能完成。本文介绍了星形胶质细胞在神经调制、突触调节和神经血管系统偶联方面的一些新进展,以期在不久的将来对星形胶质细胞的功能有更深入的了解,并能应用于临床实践。     

原代培养星形胶质细胞和小胶质细胞的特性与鉴定

本研究旨在明确原代培养的星形胶质细胞和小胶质细胞不同代次的生长特性,优化高效获取状态一致细胞的技术方法。将新生乳鼠的脑组织进行原代分离培养胶质细胞,通过细胞增殖检测试剂盒（cell counting kit-8,CCK-8）测定混合胶质细胞增殖曲线,使用流式细胞术检测两类细胞比例,并通过免疫荧光染色鉴定两类胶质细胞分型情况。生长曲线显示P0和P1代混合胶质细胞增殖活力最好;通过170 r/min机械振摇30 min可获得97.3%的高纯度小胶质细胞,该纯化方法得到的P0、P1、P2代离子钙接头蛋白-1（ionized calcium-binding adapter molecule 1,Iba-1）阳性小胶质细胞的形态及其M1、M2表型比例无代次差别;通过星形胶质细胞表面抗原-2（astrocyte cell surface antigen-2,ACSA-2）磁珠抗体分选的方法可获得纯度达到95.7%的星形胶质细胞,该纯化方法得到的P0、P1、P2代胶质纤维酸性蛋白（glial fibrillary acidic protein,GFAP）阳性星形胶质细胞的形态及其A1、A2表型比例无代次差别。本研究详述了原代分离培养的小胶质细胞和星形胶质细胞的生长特点,证明了获取两类胶质细胞的最佳代次,优化了获取两类胶质细胞的技术方法,验证了连续培养两代不会影响其功能表型。本结果为研究神经系统炎症相关疾病的分子机制提供了技术支撑。     

MiR-144通过靶向抑制GRK5表达促进脊髓星形胶质细胞活化北大核心CSCD

尽管miR-144与细胞活化、增殖有关,但其对脊髓星形胶质细胞的作用尚不明确。本文旨在探究正常和脊髓损伤(spinal cord injury,SCI)组织和细胞中miR-144表达,以及miR-144能否通过靶向调节G蛋白偶联受体激酶5(GRK5)上调脊髓星形胶质细胞活化。实时定量PCR(RT-q PCR)和Western印迹结果揭示,与正常的组织/细胞相比,miR-144在脊髓损伤组织和星形胶质细胞中的表达水平显著降低,而GRK5的表达升高;脊髓损伤大鼠的星形胶质细胞中胶质原纤维酸性蛋白(GFAP)的表达显著低于正常大鼠,而GRK5蛋白的表达高于正常大鼠;MTT分析结果显示,转染miR-144可显著提高脊髓损伤大鼠的星形胶质细胞活性,但对细胞增殖无明显作用;酶活性分析发现,miR-144显著提高SOD和GSH活性;萤光素酶报告基因检测结果证明,miR-144能靶向结合GRK5,下调GRK5表达。miR-144 mimic转染或miR-144 mimic与pc DNA-GRK5共转染脊髓损伤的星形胶质细胞后,我们发现,miR-144转染可通过激活NF-κB通路消除GRK5对细胞活化的抑制作用。综上所述,miR-144通过靶向抑制GRK5促进脊髓星形胶质细胞的活化。     

Cerebrovascular Endothelial Cell Culture: Metabolism and Synthesis of 5-Hydroxytryptamine

The presence of 5-hydroxytryptamine was investigated in cultured and propagated cerebrovascular endothelium using immunohistochemistry and high pressure liquid chromatography. These studies demonstrate that the endothelium has the ability to take up and metabolize 5-hydroxytryptamine as well as to synthesize this amine from its precursor L-tryptophan, thus providing evidence for extraneural synthesis of 5-hydroxytryptamine in the central nervous system.     

脑血管内皮细胞Prmt5在脑血管发育过程中的表达及其下游靶分子

目的:研究内皮细胞中蛋白精氨酸甲基转移酶5(PRMT5)在脑血管发育及血脑屏障建成的关键时期的表达变化及其潜在下游靶分子。方法:原位观察PRMT5在小鼠不同发育时期脑血管内皮上的分布;流式分选获得原代脑血管内皮,利用real-time PCR分析Prmt5的表达;体外培养小鼠内皮细胞敲降Prmt5后,利用Western印迹、real-time PCR、ChIP等方法检测其对经典下游分子的影响。结果:PRMT5在胚胎期各时间点的脑血管内皮细胞质均有表达,小鼠出生后主要表达在脑血管内皮细胞核,在胚胎期18.5 d时表达量显著升高;小鼠脑血管内皮细胞体外细胞系中基因敲降Prmt5后,其经典对称甲基化组蛋白产物H4R3me2s及H3R2me2s均明显下降,Bmp4表达显著上调;免疫共沉淀实验提示Bmp4启动子区域组蛋白具有H3R2me2s修饰,Prmt5基因敲降后,该组蛋白修饰显著减少。结论:脑血管发育过程中PRMT5在脑血管内皮细胞中表达的位置和水平均发生变化,脑血管内皮细胞中PRMT5可以调节H4R3和H3R2对称二甲基化水平,Bmp4启动子区域组蛋白具有H3R2me2s修饰,且PRMT5可以抑制Bmp4表达。     

Transcription-Independent Activation of Ornithine Decarboxylase Activity by Heparin in Cloned Cerebral Endothelial Cells

Abstract: Heparin, a highly sulfated glycosaminoglycan, is known to be obligatory for long-term endothelial cell cultures; it potentiates the mitogenic activities of endothelial cell growth factors and prolongs the replicative life span of the cells. Here we have shown that besides its growth factor-supportive role, heparin exerts a specific action on cerebral capillary endothelial cells (cECs), unrelated to serum or growth factors, by increasing activity of ornithine decarboxylase (ODC; EC 4.1.1.17) in these cells. For our experiments we have used two different types of cloned cECs: type I cECs, grown in the presence of endothelial cell growth factor and heparin, and type II cECs, usually cultivated without growth factors. Heparin action on ODC activity was shown to be dose dependent within the range of 1–100 μg/ml. Increasing concentrations of or depletion of endothelial cell growth factor from type I cultures had no effect on ODC activity. The increase in enzyme activity was highest after 30 min to 1 h of heparin treatment. As evidenced by northern analysis, the heparin-mediated enhancement of ODC activity was not accompanied by changes of ODC mRNA levels. Studies of DNA replication revealed that in the absence of heparin-binding growth factors, heparin did not affect the proliferative activity of cloned cECs.     

长链非编码RNA GAS5抑制内皮细胞功能

最新研究表明,长链非编码RNA GAS5（lncRNA GAS5）可调节血管内皮细胞的凋亡,但对内皮细胞其他功能的调控并不明确。本研究旨在了解lncRNA GAS5对内皮细胞的增殖、成血管、NO分泌及内皮标志分子CD31和vWF表达的影响及可能机制。将LncRNA GAS5干扰慢病毒（LV-GAS5-RNAi）转染人脐静脉内皮细胞株（EA.hy926）后,采用CCK8及Matrigel胶分别检测EA.hy926的增殖和成血管能力;硝酸还原酶法检测NO的分泌情况;real-time RT-PCR检测CD31、vWF及miR-21的表达;Western印迹检测PTEN在蛋白质水平的表达。结果显示：与对照组比较,LV-GAS5-RNAi组EA.hy926增殖能力无明显变化(0.34±0.01 vs. 0.34±0.04,P>0.05),而其成血管能力升高(133.70±12.64 vs. 100.00±4.65,P<0.05),NO的分泌量亦增加(28.54±2.75 μmol/L vs.15.11±1.19 μmol/L,P<0.01);内皮标志分子CD31（是对照组的1.46倍）及vWF（是对照组的2.94倍)的基因表达量均显著升高。同时,miR-21表达亦明显升高(是对照组的1.42倍),而miR-21下游靶基因PTEN蛋白质的表达量则显著降低（0.13±0.05 vs. 0.38±0.03,P<0.01）。以上结果提示,LncRNA GAS5抑制了内皮细胞的功能,miR-21、PTEN信号分子可能参与其中的调节。     

Hela l-CaD Is Implicated in the Migration of Endothelial Cells/Endothelial Progenitor Cells in Human Neoplasms

Caldesmon (CaD) is a major actin-binding protein distributed in a variety of cell types. No functional differences among the isoforms in in vitro studies were found so far. In a previous study we found that the low molecular caldesmon isoform (Hela l-CaD) is expressed in endothelial cells (ECs)/endothelial progenitor cells (EPCs) in tumor vasculature of various human tumors. Activation of cell motility is necessary for the navigation of the tip ECs during angiogenesis, and migration of EPCs from the bone marrow during vasculogenesis. In the present study we searched for features of motility and the intracellular expression sites of Hela l-CaD in ECs/EPCs of various human tumors under histologically preserved microenviroment. We discovered a variety of motility-related cell protrusions like filopodia, microspikes, lamellipodia, podosomes, membrane blebs and membrane ruffles in the activated ECs/EPCs. Hela l-CaD appeared to be invariably expressed in the subregions of these cell protrusions. The findings suggest that Hela l-CaD is implicated in the migration of ECs/EPC in human neoplasms where they contribute to tumor vasculogenesis and angiogenesis.     

小鼠胚胎干细胞定向血管内皮和造血细胞分化体系的建立

目的:建立小鼠胚胎干细胞体外定向分化为血管内皮细胞和造血细胞的体系,并验证诱导后2种细胞的表面分子特征。方法:以小鼠胚胎成纤维细胞为饲养层,首先在无血清培养基StemPro中加入骨形态发生蛋白4(BMP4)、激活素A、碱性成纤维细胞生长因子(FGF-Basic)和血管内皮细胞生长因子(VEGF),诱导小鼠胚胎干细胞系R1/E 4 d后形成拟胚体;再将拟胚体消化后与OP9-DL1基质细胞共孵育,分别用干细胞因子(SCF)、VEGF和SCF、FLt3、白细胞介素3(IL-3)诱导向内皮和造血2个方向分化,并以CD31、CD45、CD144、Kit、CD201作为表面标志,流式检测诱导后细胞的表面分子特征和诱导效率;诱导10 d后免疫组化染色,进行内皮细胞的形态学鉴定。结果:诱导分化10 d后,免疫组化染色观察到多个内皮管状结构,流式检测CD31^+的内皮细胞比例为1.35%±0.05%,进一步分析CD31^+CD144^+CD45^-群体,有3.0%±0.2%的细胞表型为Kit^+CD201^+,提示该部分细胞可能是处于分化上游的内皮干祖细胞;CD45^+的造血细胞比例为35.0%±0.5%,其中0.35%±0.05%的细胞表达Kit和CD201,提示该部分细胞可能是处于分化上游的造血干祖细胞。结论:本研究将胚胎干细胞诱导为内皮细胞和造血细胞,并且能诱导出具有内皮、造血干祖细胞分子特征的细胞,可作为理想的体外诱导分化体系。     

大鼠脑微血管内皮细胞的分离与原代培养

为了建立大鼠脑微血管内皮细胞体外培养模型,探索纯度较高的大鼠脑微血管内皮细胞分离和原代培养的方法并进行形态学观察。采用2～3周龄的SD大鼠,解剖得到大脑皮质,两次酶消化及牛血清白蛋白或葡聚糖和Percoll梯度离心获得较纯的脑微血管段后,接种于涂布基质的培养皿进行原代培养;培养的细胞采用相差显微镜形态学观察、透射电镜观察及Ⅷ因子相关抗原免疫组化检测鉴定。结果发现,培养12h即可见细胞从贴壁的脑微血管段周围长出,细胞呈短梭形,区域性单层生长,5～7天内皮细胞融合,内皮细胞纯度达90％以上;内皮细胞的贴壁和生长有赖于所涂布的基质,纤连蛋白／Ⅳ型胶原优于鼠尾胶和明胶;Ⅷ因子相关抗原免疫组化检测内皮细胞表达阳性,透射电镜观察可见相邻内皮细胞间存在紧密连接结构。提示该方法能成功进行纯度较高的大鼠脑微血管内皮细胞原代培养,可用于脑微血管内皮的生理、生化及药理学研究,亦可用于构建大鼠血脑屏障模型。     

Characterization of the Scavenger Receptor on Bovine Cerebral Endothelial Cells In Vitro

Abstract— Primary cultures of bovine brain capillary endo-thelial cells (BCEC), possessing tight junctions and high levels of γ-glutamyl transpeptidase, were used as an in vitro model for the blood-brain barrier. The interaction of acetylated low density lipoprotein (AcLDL) with BCEC was studied to characterize the scavenger receptor on these cells. A saturable high affinity binding site was found with a dissociation constant of AcLDL of 5.4 μg/ml (3.1 n M ) and a maximal binding ranging from 284 to 626 ng of AcLDL/mg of cell protein for eight primary cultures, and independent of the presence of calcium. Cell association was coupled to degradation, and both could be effectively competed for by polyinosinic acid and AcLDL but not by low density lipoprotein or by high density lipoprotein. Prolonged incubation showed an accumulation of the ligand in the cells. The rate of degradation of AcLDL was ∼ 10–20-fold lower in BCEC than that of peripheral endothelial cells. No evidence for lysosomal degradation could be obtained. Binding of 1,1'-dioctadecyl-3,3,3,3'-tetramethylindocar-boxyamine perchlorate-labeled AcLDL by BCEC was observed, which could be competed for by an excess of un-labeled AcLDL and polyinosinic acid. We have shown that in vitro BCEC possesses specific binding sites for AcLDL, whereas these cells show a relatively low degradative capacity.     

Isolation and Culture Expansion of Tumor-specific Endothelial Cells

Freshly isolated tumor-specific endothelial cells (TEC) can be used to explore molecular mechanisms of tumor angiogenesis and serve as an in vitro model for developing new angiogenesis inhibitors for cancer. However, long-term in vitro expansion of murine endothelial cells (EC) is challenging due to phenotypic drift in culture (endothelial-to-mesenchymal transition) and contamination with non-EC. This is especially true for TEC which are readily outcompeted by co-purified fibroblasts or tumor cells in culture. Here, a high fidelity isolation method that takes advantage of immunomagnetic enrichment coupled with colony selection and in vitro expansion is described. This approach generates pure EC fractions that are entirely free of contaminating stromal or tumor cells. It is also shown that lineage-traced Cdh5^cre:ZsGreen^l/s/l reporter mice, used with the protocol described herein, are a valuable tool to verify cell purity as the isolated EC colonies from these mice show durable and brilliant ZsGreen fluorescence in culture.