C-reactive protein decreases expression of VEGF receptors and neuropilins and inhibits VEGF165-induced cell proliferation in human endothelial cells

C-reactive protein (CRP) is associated with cardiovascular disease. However, its biological functions for the vascular system are largely unknown. The objective of this study was to determine whether CRP could affect endothelial cell proliferation and expression of VEGF receptors (VEGFRs) and/or neuropilins. Human coronary artery endothelial cells (HCAECs) treated with CRP showed a significant reduction of mRNA levels of VEGFR-2, VEGFR-3, NRP-1, and NRP-2 by 34%, 63%, 41%, and 43%, respectively, as compared to untreated control cells (p < 0.05) by real-time PCR analysis. In addition, VEGF165-induced cell proliferation was determined by [3H]thymidine incorporation and MTS assay as well as capillary-like tube formation on Matrigel. HCAECs pretreated with CRP significantly decreased VEGF165-induced [3H]thymidine incorporation by 73%, MTS absorbance by 44%, and capillary-like tube formation by 54% as compared to CRP-untreated cells (p < 0.05). These data demonstrate that CRP significantly attenuates VEGF165-induced HCAEC proliferation and capillary-like tube formation through downregulation of expression of VEGFRs and NRPs. This study suggests a new molecular mechanism underlying the adverse effect of CRP on the vascular system.     

Heparan sulfate regulates VEGF165- and VEGF121-mediated vascular hyperpermeability

VEGF was first described as vascular permeability factor, a potent inducer of vascular leakage. Genetic evidence indicates that VEGF-stimulated endothelial proliferation in vitro and angiogenesis in vivo depend on heparan sulfate, but a requirement for heparan sulfate in vascular hyperpermeability has not been explored. Here we show that altering endothelial cell heparan sulfate biosynthesis in vivo decreases hyperpermeability induced by both VEGF(165) and VEGF(121). Because VEGF(121) does not bind heparan sulfate, the requirement for heparan sulfate suggested that it interacted with VEGF receptors rather than the ligand. By applying proximity ligation assays to primary brain endothelial cells, we show a direct interaction in situ between heparan sulfate and the VEGF receptor, VEGFR2. Furthermore, the number of heparan sulfate-VEGFR2 complexes increased in response to both VEGF(165) and VEGF(121). Genetic or heparin lyase-mediated alteration of endothelial heparan sulfate attenuated phosphorylation of VEGFR2 in response to VEGF(165) and VEGF(121), suggesting that the functional VEGF receptor complex contains heparan sulfate. Pharmacological blockade of heparan sulfate-protein interactions inhibited hyperpermeability in vivo, suggesting heparan sulfate as a potential target for treating hyperpermeability associated with ischemic disease.     

人VEGF165基因转染成人成肌细胞的实验研究

目的：将人血管内皮生长因子165（hVEGF165）导人原代离体成肌细胞,观察该细胞hVEGF分泌情况,探讨成人自体转基因成肌细胞移植的可行性。方法：采用两步消化法对成人骨骼肌组织消化获取相对较纯的成肌细胞,通过差速贴壁法进行进一步的纯化。以脂质体转染法将pcDNA3．1-hVEGF165导入成肌细胞,通过RT—PCR、ELISA和Western-blot进行hVEGF165定量检测,MTT测定和Mile’s实验检测VEGF165的生物学活性。结果：转基因细胞经RT—PCR扩增出一条VEGF的特异性泳带,ELISA显示转基因细胞培养上清VEGF浓度分别达到18．92±1．77rig／mL、19．04±2．15ng／mL,Western blot检测转基因成肌细胞上清均检测到VEGF蛋白特异性的杂交带,MTT显示转基因细胞上清明显促内皮细胞增殖,Mile’s实验显示转基因细胞上清明显增加毛细血管通透性。结论：质粒pcDNA3．1-hVEGF165能成功转入成人成肌细胞,转基因细胞能分泌有生物活性的VEGF165蛋白。     

pEGFP-N1质粒转染乳鼠心肌细胞的分布及效率

目的: 研究pEGFP-N1质粒转染心肌细胞的分布及效率.方法: 培养乳鼠心肌细胞,根据乳鼠心肌细胞的不同生长时间(1～3 d)进行pEGFP-N1质粒转染心肌细胞的实验研究.结果: 乳鼠心肌细胞生长1 d时,pEGFP-N1质粒转染心肌细胞的效率显著高于乳鼠心肌细胞生长2 d、3 d时;pEGFP-N1质粒转染心肌细胞后EGFP均匀地充满胞浆和胞核.结论: pEGFP-N1质粒转染乳鼠心肌细胞的效率与心肌细胞的生长期有关;EGFP在心肌细胞中均匀分布于胞浆和胞核.     

Simvastatin stimulates VEGF release via p44/p42 MAP kinase in vascular smooth muscle cells

It has been shown that 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) modulate vascular smooth muscle cell functions. In the present study, we investigated the effect of simvastatin on vascular endothelial growth factor (VEGF) release, and the underlying mechanism, in a rat aortic smooth muscle cell line, A10 cells. Administration of simvastatin increased the VEGF level in rat plasma in vivo. In cultured cells, simvastatin significantly stimulated VEGF release in a dose-dependent manner. Simvastatin induced the phosphorylation of p44/p42 MAP kinase but not p38 MAP kinase or SAPK (stress-activated protein kinase)/JNK (c-Jun N-terminal kinase). PD98059 and U-0126, inhibitors of the upstream kinase that activates p44/p42 MAP kinase, significantly reduced the simvastatin-induced VEGF release in a dose-dependent manner. The phosphorylation of p44/p42 MAP kinase induced by simvastatin was reduced by PD98059 or U-0126. Moreover, a bolus injection of PD98059 truly suppressed the simvastatin-increased VEGF level in rat plasma in vivo. These results strongly suggest that p44/p42 MAP kinase plays a role at least partly in the simvastatin-stimulated VEGF release in vascular smooth muscle cells.     

High efficiency transfection of porcine vascular cells in vitro with a synthetic vector system

Background

Gene therapy strategies for the treatment of vascular disease such as the prevention of post‐angioplasty restenosis require efficient, non‐toxic transfection of vascular cells. In vitro studies in these cells contribute to vector development for in vivo use and for the evaluation of genes with therapeutic potential. The aim of this project was to evaluate a novel synthetic vector consisting of a liposome (L), an integrin targeting peptide (I), and plasmid DNA (D), which combine to form the LID vector complex.

Methods

Cultures of porcine smooth muscle cells and endothelial cells were established and then transfected with the LID vector, using the reporter genes luciferase and green fluorescent protein and the metalloprotease inhibitor TIMP‐1.

Results

The LID vector system transfected primary porcine vascular smooth muscle cells and porcine aortic endothelial cells with efficiency levels of 40% and 35%, respectively. By increasing the relative DNA concentration four‐fold, incubation periods as short as 30 min achieved the same levels of luciferase transgene expression as 4 h incubations at lower DNA concentrations. The transfection did not affect cell viability as measured by their proliferative potential. Serum levels of up to 20% in the transfection medium had no adverse affect on the efficiency of transfer and gene expression in either cell type. Transfections with the cDNA for TIMP‐1 produced protein levels that peaked at 130 ng/ml per 24 h and persisted for 14 days at 10 ng/ml per 24 h.

Conclusion

This novel vector system has potential for studies involving gene transfer to cardiovascular cells in vitro and in vivo. Copyright © 2002 John Wiley & Sons, Ltd.

     

Macrophage migration inhibitory factor (MIF) promotes rat airway muscle cell proliferation and migration mediated by ERK1/2 and FAK signaling

Macrophage migration inhibitory factor (MIF) is an inflammatory mediator that contributes to asthmatic airway remodeling; however, little is known regarding the effects of MIF on airway smooth muscle cells (ASMCs). In the present study, we found that an enhanced expression of MIF promoted ASMC proliferation, increased the population of cells in the S/G2 phase, downregulated P21 expression, and upregulated cyclin D1, cyclin D3, and Cdk6 expression. In addition, the apoptosis of ASMCs was significantly decreased in response to MIF overexpression, compared with the negative control. Moreover, MIF facilitated the migration of ASMCs by upregulating the expression of matrix metalloproteinase (MMP)‐2. Finally, we showed that MIF increased the phosphorylation of extracellular regulated protein kinases (ERK) 1/2 and focal adhesion kinase (FAK), which are associated with proliferation and migration. In conclusion, this study demonstrated that MIF overexpression promotes the proliferation and migration of ASMCs by upregulating the activity of the ERK1/2 and FAK signaling pathways in these cells, further indicating that inhibition of MIF may prove to be an effective strategy for treating asthma patients with airway remodeling.     

人VEGF基因转染大鼠骨髓间充质干细胞的实验研究

为建立hVEGF165基因转染大鼠间充质干细胞的方法．采用密度梯度离心-贴壁培养法获Wistar大鼠BMMSC,并测定其生长曲线和表面标志CD34、CD44、CD45及SH3,然后向成骨细胞及脂肪细胞诱导分化;用脂质体介导pcDNA3.1-hVEGF165转染BMMSC,观察转染后细胞形态和生长情况的变化,通过RT-PCR、Western和ELISA鉴定VEGF在细胞中的表达情况．经培养的大鼠BMMSC,CD44、SH3检测为阳性．CD45、CD34阴性,可诱导分化为成骨细胞和脂肪细胞;经RT-PCR、Western和ELISA检测证实阳离子脂质体能成功地将hVEGF165基因转染至大鼠BMMSC中,并获得有效的表达．真核表达栽体pcDNA3.1-hVEGF165在BMMSC中获有效表达,为VEGF基因转染BMMSC移植对心梗后大鼠心功能及心室重构的影响提供了实验依据．     

重组人VEGF165的表达纯化及单抗的初步筛选

血管内皮细胞生长因子(vascular endothelial growth factor, VEGF)是抑制肿瘤生长和转移的重要靶点。为获得抗VEGF单抗细胞株,构建了rhVEGF₁₆₅工程菌,并利用复合自动诱导获得高效表达。经纯化获得高纯度rhVEGF₁₆₅蛋白,经检测具有促人脐静脉内皮细胞(human umbilical vein endothelial cells, HUVECs)增殖活性,其EC₅₀为2.4ng/ml。免疫小鼠,获得了3株能稳定分泌抗VEGF单抗的杂交瘤细胞株,为开发VEGF治疗性单抗提供了重要基础。     

PEG-PEI共聚物介导VEGF165基因转染及对内皮细胞生长的影响

为了考察PEG-PEI共聚物作为基因载体介导VEGF165基因的能力,合成不同接枝量的PEG-PEI共聚物,考察共聚物的细胞毒性,同时采用PCR技术获得上下游含有HindⅢ和BamHⅠ酶切位点的目的基因VEGF165,与pEGFP-C1构建重组质粒pEGFP-VEGF165,将PEG-PEI作为基因载体,与pEGFP-VEGF165通过自组装成DNA复合物,使其转染脐静脉内皮细胞(HUVEc),测定发荧光细胞百分数获得转染率,利用ELISA、RT-PCR检测VEGF的表达,用MTT法考察VEGF165转染HUVEc后对内皮细胞生长的影响.结果显示,形成PEG-PEI共聚物后可显著降低PEI的细胞毒性.作为基因载体介导pEGFP-VEGF165转染HUVEc后,在荧光显微镜下可见强绿色荧光蛋白表达,转染率与接枝PEG的量及N/P有关,PEG-PEI(5-25-1)在N/P=30时转染率达到最大值,比PEI显著提高.转染后血管内皮生长因子(VEGF)蛋白表达及mRNA水平均有显著提高,且可有效地刺激内皮细胞增殖.研究表明,PEG-PEI共聚物可做为基因载体,有效地介导pEGFP-VEGF165基因的传递.     

重组腺病毒介导VEGF121 cDNA体外转移与表达

构建携带VEGF12 1cDNA重组复制缺陷型腺病毒表达载体 ,制备重组腺病毒 ,该腺病毒能介导VEGF12 1cDNA基因促进人脐静脉血管内皮细胞增殖 ,促进毛细血管管腔样结构形成 .ELISA检测表明VEGF12 1cDNA基因表达产物分泌至培液上清 ,并显示强烈血管通透作用 .为进一步利用重组腺病毒介导VEGF12 1cDNA进行缺血性疾病的基因治疗奠定良好的基础     

Involvement of p38 MAP kinase in TGF-beta-stimulated VEGF synthesis in aortic smooth muscle cells

Although it is known that transforming growth factor (TGF)-beta induces vascular endothelial growth factor (VEGF) synthesis in vascular smooth muscle cells, the underlying mechanisms are still poorly understood. In the present study, we examined whether the mitogen-activated protein (MAP) kinase superfamily is involved in TGF-beta-stimulated VEGF synthesis in aortic smooth muscle A10 cells. TGF-beta stimulated the phosphorylation of p42/p44 MAP kinase and p38 MAP kinase, but not that of SAPK (stress-activated protein kinase)/JNK (c-Jun N-terminal kinase). The VEGF synthesis induced by TGF-beta was not affected by PD98059 or U0126, specific inhibitors of the upstream kinase that activates p42/p44 MAP kinase. We confirmed that PD98059 or U0126 did actually suppress the phosphorylation of p42/p44 MAP kinase by TGF-beta in our preparations. PD169316 and SB203580, specific inhibitors of p38 MAP kinase, significantly reduced the TGF-beta-stimulated synthesis of VEGF (each in a dose-dependent manner). PD169316 or SB203580 attenuated the TGF-beta-induced phosphorylation of p38 MAP kinase. These results strongly suggest that p38 MAP kinase plays a part in the pathway by which TGF-beta stimulates the synthesis of VEGF in aortic smooth muscle cells.     

Thymoquinone suppresses platelet‐derived growth factor‐BB–induced vascular smooth muscle cell proliferation,migration and neointimal formation

The excessive proliferation and migration of vascular smooth muscle cells (VSMCs) are mainly responsible for vascular occlusion diseases, such as pulmonary arterial hypertension and restenosis. Our previous study demonstrated thymoquinone (TQ) attenuated monocrotaline‐induced pulmonary arterial hypertension. The aim of the present study is to systematically examine inhibitory effects of TQ on platelet‐derived growth factor‐BB (PDGF‐BB)–induced proliferation and migration of VSMCs in vitro and neointimal formation in vivo and elucidate the potential mechanisms. Vascular smooth muscle cells were isolated from the aorta in rats. Cell viability and proliferation were measured in VSMCs using the MTT assay. Cell migration was detected by wound healing assay and Transwell assay. Alpha‐smooth muscle actin (α‐SMA) and Ki‐67‐positive cells were examined by immunofluorescence staining. Reactive oxygen species (ROS) generation and apoptosis were measured by flow cytometry and terminal deoxyribonucleotide transferase–mediated dUTP nick end labelling (TUNEL) staining, respectively. Molecules including the mitochondria‐dependent apoptosis factors, matrix metalloproteinase 2 (MMP2), matrix metalloproteinase 9 (MMP9), PTEN/AKT and mitogen‐activated protein kinases (MAPKs) were determined by Western blot. Neointimal formation was induced by ligation in male Sprague Dawley rats and evaluated by HE staining. Thymoquinone inhibited PDGF‐BB–induced VSMC proliferation and the increase in α‐SMA and Ki‐67‐positive cells. Thymoquinone also induced apoptosis via mitochondria‐dependent apoptosis pathway and p38MAPK. Thymoquinone blocked VSMC migration by inhibiting MMP2. Finally, TQ reversed neointimal formation induced by ligation in rats. Thus, TQ is a potential candidate for the prevention and treatment of occlusive vascular diseases.     

VEGF165 mediates formation of complexes containing VEGFR-2 and neuropilin-1 that enhance VEGF165-receptor binding

Co-expression of NRP1 and (VEGFR-2) KDR on the surface of endothelial cells (EC) enhances VEGF165 binding to KDR and EC chemotaxis in response to VEGF165. Overexpression of NRP1 by prostate tumor cells in vivo results in increased tumor angiogenesis and growth. We investigated the molecular mechanisms underlying NRP1-mediated angiogenesis by analyzing the association of NRP1 and KDR. An intracellular complex containing NRP1 and KDR was immunoprecipitated from EC by anti-NRP1 antibodies only in the presence of VEGF165. In contrast, VEGF121, which does not bind to NRP1, did not support complex formation. Complexes containing VEGF165, NRP1, and KDR were also formed in an intercellular fashion by co-culture of EC expressing KDR only, with cells expressing NRP1 only, for example, breast carcinoma cells. VEGF165 also mediated the binding of a soluble NRP1 dimer to cells expressing KDR only, confirming the formation of such complexes. Furthermore, the formation of complexes containing KDR and NRP1 markedly increased 125I-VEGF165 binding to KDR. Our results suggest that formation of a ternary complex of VEGF165, KDR, and NRP1 potentiates VEGF165 binding to KDR. These complexes are formed on the surface of EC and in a juxtacrine manner via association of tumor cell NRP1 and EC KDR.     

内皮细胞生长状态对血管平滑肌细胞增生迁移的影响

实验通过建立细胞共培养体系,探讨内皮细胞生长状态对血管平滑肌细胞增生迁移的影响及机制。检测指标包括~3H-TdR掺入、细胞周期、细胞迁移计数和α-SM-actin mRNA表达。结果显示,融合生长内皮使平滑肌细胞~3H-TdR掺入量明显降低,增加平滑肌细胞停留在G_0/G_1期的比例,上调平滑肌细胞α-SM-actin mRNA表达;而对数生长内皮细胞使平滑肌细胞~3H-TdR掺入量明显升高,促进平滑肌细胞由 G_0/G_1期进入G_2/M和S期,下调平滑肌细胞α-SM-actin mRNA表达。对照组平滑肌细胞在基础状态下存在少量迁移,对数增殖内皮细胞组平滑肌迁移数比对照组增高约4倍(P<0.01),而融合生长内皮细胞组平滑肌迁移数仅为对照组的0.5倍(P<0.05)。结果提示内皮细胞生长状态不同,对平滑肌细胞生物学特性的影响也不同,增殖期内皮明显促进平滑肌细胞增生迁移、下调平滑肌细胞α-SM-actin mRNA表达。     

ERK,JNK, and p38 MAP kinases differentially regulate proliferation and migration of phenotypically distinct smooth muscle cell subtypes

Proliferation and migration of vascular smooth muscle cells (SMCs) are important processes involved in the pathogenesis of vascular disorders such as atherosclerosis and post-angioplasty restenosis. Here we demonstrate that proliferation and migration of specific SMC subtypes is mitogen-activated protein (MAP) kinase-dependent. WKY12-22 SMCs derived from the aortae of 12 day-old pup rats proliferate and migrate faster than WKY3M-22 SMCs derived from the aortae of adult rats. WKY12-22 and WKY3M-22 cells equally expressed the active forms of phospho (Thr(183)/Tyr(185))-c-Jun N-terminal kinase (JNK) and phospho (Tyr(182))-p38, whereas the activity of extracellular signal-regulated kinase (ERK) was greater in WKY12-22 cells compared with WKY3M-22 cells. Proliferation of both SMC subtypes was attenuated by PD98059, SP600125 and SB202190, inhibitors of ERK, JNK, and p38, respectively. However, inhibition of PD98059 had a more profound effect on WKY12-22 SMCs. Furthermore, migration of WKY12-22 and WKY3M-22 cells was inhibited by SP600125 and SB202190, however, PD98059 failed to influence migration of either SMC subtype. Hence, migration of both SMC subtypes is JNK- and p38-dependent, but not ERK-dependent. These findings demonstrate that SMC heterogeneity is mediated, at least in part, by the activity of specific MAP kinase subtypes.     

Insert sequence length determines transfection efficiency and gene expression levels in bicistronic mammalian expression vectors

Bicistronic expression vectors have been widely used for co-expression studies since the initial discovery of the internal ribosome entry site (IRES) about 25 years ago. IRES sequences allow the 5’ cap-independent initiation of translation of multiple genes on a single messenger RNA strand. Using a commercially available mammalian expression vector containing an IRES sequence with a 3’ green fluorescent protein fluorescent marker, we found that sequence length of the gene of interest expressed 5’ of the IRES site influences both expression of the 3’ fluorescent marker and overall transfection efficiency of the vector construct. Furthermore, we generated a novel construct expressing two distinct fluorescent markers and found that high expression of one gene can lower expression of the other. Observations from this study indicate that caution is warranted in the design of experiments utilizing an IRES system with a short 5’ gene of interest sequence (<300 bp), selection of single cells based on the expression profile of the 3’ optogenetic fluorescent marker, and assumptions made during data analysis.     

VEGF165 induces differentiation of hair follicle stem cells into endothelial cells and plays a role in in vivo angiogenesis

Within the vascular endothelial growth factor (VEGF) family of five subtypes, VEGF165 secreted by endothelial cells has been identified to be the most active and widely distributed factor that plays a vital role in courses of angiogenesis, vascularization and mesenchymal cell differentiation. Hair follicle stem cells (HFSCs) can be harvested from the bulge region of the outer root sheath of the hair follicle and are adult stem cells that have multi‐directional differentiation potential. Although the research on differentiation of stem cells (such as fat stem cells and bone marrow mesenchymal stem cells) to the endothelial cells has been extensive, but the various mechanisms and functional forms are unclear. In particular, study on HFSCs’ directional differentiation into vascular endothelial cells using VEGF165 has not been reported. In this study, VEGF165 was used as induction factor to induce the differentiation from HFSCs into vascular endothelial cells, and the results showed that Notch signalling pathway might affect the differentiation efficiency of vascular endothelial cells. In addition, the in vivo transplantation experiment provided that HFSCs could promote angiogenesis, and the main function is to accelerate host‐derived neovascularization. Therefore, HFSCs could be considered as an ideal cell source for vascular tissue engineering and cell transplantation in the treatment of ischaemic diseases.