The inhibitory effects of endostatin on endothelial cells are modulated by extracellular matrix

We investigated the ability of extracellular matrix (ECM) proteins to modulate the response of endothelial cells to both promoters and inhibitors of angiogenesis. Using human dermal microvascular endothelial cells (HDMEC), we found that cells demonstrated different adhesive properties and proliferative responses to the growth factor VEGF depending upon which ECM protein with which they were in contact, with fibronectin having the most impact on VEGF-induced HDMEC proliferation and survival. More importantly, we observed that ECM could modulate the ability of the angiogenic inhibitor endostatin to prevent endothelial cell proliferation, survival and migration. We observed that growth on vitronectin or fibronectin impaired the ability of endostatin to inhibit VEGF-induced HDMEC proliferation to the greatest extent as determined by BrdU incorporation. We found that, following growth on collagen I or collagen IV, endostatin only inhibited VEGF-induced HDMEC proliferation at the highest dose tested (2500 ng/ml). In a similar manner, we observed that growth on ECM proteins modulated the ability of endostatin to induce endothelial cell apoptosis, with growth on collagen I, fibronectin and collagen IV impairing endostatin-induced apoptosis. Interestingly, endostatin inhibited VEGF-induced HDMEC migration following culture on collagen I, collagen IV and laminin, while migration was not inhibited by endostatin following HDMEC culture on other matrices including vitronectin, fibronectin and tenascin-C. These results suggest that different matrix proteins may affect different mechanisms of endostatin inhibition of angiogenesis. Taken together, our results suggest that the ECM may have a profound impact on the ability of angiostatic molecules such as endostatin to inhibit angiogenesis and thus may have impact on the clinical efficacy of such inhibitors.     

Regulation of podosome formation in aortic endothelial cells vessels by physiological extracellular cues

Invadosomes are specialised actin-based dynamic microdomains of the plasma membrane. Their occurrence has been associated with cell adhesion, matrix degrading and mechanosensory functions that make them crucial regulators of cell migration and invasion. Monocytic, cancer cell and Src-transformed cell invadosomes have been extensively described. Less well defined are the structures which form in other cell types, i.e., non-haematopoietic and non-transformed cells, exposed to specific stimuli. We herein describe the specificities of podosomes induced in aortic endothelial cells stimulated with TGFβ in vitro and in conditions that more closely resemble the in vivo situation. These podosomes display the typical architecture of monocytic podosomes. They organise into large rosette-shape superstructures where they exhibit collective dynamic behavior consisting in cycles of formation and regression. At the ultrastructural level, microfilament arrangements in individual podosomes were revealed. Oxygen levels and hemodynamic forces, which are key players in endothelial cell biology, both influence the process. In 3D environment, podosomes appear as globular structures along cellular extensions. A better characterization of endothelial podosomes has far-reaching implications in the understanding and, possibly, in the treatment of some vascular diseases.     

Papaverine induces apoptosis in vascular endothelial and smooth muscle cells

Papaverine is a vasodilator commonly used in the treatment of vasospasmic diseases such as cerebral spasm associated with subarachnoid hemorrhage, and in the prevention of spasm of coronary artery bypass graft by intraluminal and/or extraluminal administration. In this study, we examined whether papaverine in the range of concentrations used clinically causes apoptosis of vascular endothelial and smooth muscle cells. Apoptotic cells were identified by morphological changes and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay. In porcine coronary endothelial cells (EC) and rat aortic smooth muscle cells (SMC), papaverine at the concentration of 10(-3) M induced membrane blebbing within 1 hour of incubation. Nuclear condensation and fragmentation were found after 24 hours of treatment. The number of apoptotic cells stained with the TUNEL method was significantly higher in the EC and the SMC after 24 hours of incubation with papaverine at the concentrations of 10(-4) and 10(-3) M than their respective controls. Acidified saline solution (pH 4.8, as control for 10(-3) M papaverine hydrochloride) did not cause apoptosis in these cells. These results showed that papaverine could damage endothelial and smooth muscle cells by inducing changes which are associated with events leading to apoptosis. Since integrity of endothelial cells is critical for normal vascular function, vascular administration of papaverine for clinical use, especially at high concentrations (> or = 10(-4) M), should be re-considered.     

角膜内皮细胞再生研究新进展

人角膜内皮细胞的主要功能是维持角膜透明性,角膜内皮单层发育成熟形成细胞接触后,内皮细胞会停止分裂增殖,但并没有退出细胞周期。角膜内皮细胞的增殖有多种因素的参与和影响,接触抑制和G1期抑制使细胞增殖暂时停止;细胞因子TGF-β2抑制人角膜内皮细胞进入细胞周期S期,而EGF、FGF、NGF则能够促进细胞的增殖;ROCK抑制剂Y-27632能够促进角膜内皮细胞的粘连,有助于内皮细胞的损伤修复。体外培养角膜内皮前体细胞、诱导多潜能干细胞向角膜内皮细胞分化,为今后治疗角膜内皮失代偿提供了新方向。     

Impact of glafenine hydrochloride on human endothelial cells and human vascular smooth muscle cells: a substance reducing proliferation, migration and extracellular matrix synthesis

The aim of this study was to examine the effects of glafenine hydrochloride (a nonsteroidal anti-inflammatory drug) on proliferation, clonogenic activity, cell-cycle, migration, and the extracellular matrix protein tenascin of human aortic smooth muscle cells (haSMCs) and human endothelial cells (ECs) in vitro.HaSMCs and ECs were seeded in tissue culture flasks. The cells were treated for 4 days with glafenine hydrochloride (10 microM, 50 microM, 100 microM). Half of the treated groups were incubated again with glafenine hydrochloride, the other half received medium free of glafenine hydrochloride every 4 days until day 20. The growth kinetics and clonogenic activity were assessed. Cell cycle distribution was investigated by FACS, migratory ability was evaluated, and effects on extracellular matrix synthesis were assessed by immunofluorescence.Glafenine hydrochloride inhibited the proliferation and clonogenic activity of haSMCs and ECs in a dose-dependent manner. A block in the G2/M phase and a reduction in the G1 phase occurred. The migratory ability of haSMCs was impaired in a dose-dependent manner and the extracellular matrix protein tenascin was reduced. As glafenine hydrochloride has the ability to fully inhibit proliferation and to partially inhibit migration in haSMCs, it could be an interesting substance for further research in the field of restenosis therapy.     

Aging effects on the elastin composition in the extracellular matrix of cultured rat aortic smooth muscle cells

Summary Elastin accumulation in the extracellular matrix of cultured rat aortic smooth muscle cells was monitored as a function of age. The effect of the animal donor age and time in culture in single or consecutive passages on the cells’ ability to accumulate total protein as well as elastin was evaluated. Smooth muscle cells were obtained from animals ranging in age from 2 d to 36 mo. Protein accumulation by the cells based on DNA content was similar regardless of which of the above aging parameters was examined. Although there were significant amounts of elastin present in the extracellular matrix of those cells originating from the younger animals (2 d and 6 wk old), little or none was detected in cell cultures derived from the oldest animals. A soluble elastin-like fraction which was isolated from the cultures of the 2-d-old rats seemed to be lacking in the cultures of cells from the 36-mo-old animals. This observation may, in part, explain the absence of insoluble elastin in the matrix of some cultures obtained from older animals. The data strongly suggest that the age of the donor animal from which the cells originate has the greatest influence on in vitro elastin accumulation. This study was supported by National Institutes of Health Grants HL 19717 and HL 13262.     

Enhanced assay of endothelial exocytosis using extracellular matrix components

Vascular inflammation plays a key role in the pathogenesis of atherosclerosis. The first step in vascular inflammation is endothelial exocytosis, in which endothelial granules fuse with the plasma membrane, releasing prothrombotic and proinflammatory messenger molecules. The development of cell culture models to study endothelial exocytosis has been challenging because the factors that modulate exocytosis in vitro are not well understood. Here we report a method for studying endothelial exocytosis that optimizes extracellular matrix components, cell density, and duration of culture. Human umbilical vein endothelial cells plated on collagen I-coated plates and cultured in the confluent state for 7–12 days in low-serum medium showed robust secretion of von Willebrand factor when stimulated with various agonists. This exocytosis assay is rapid and applicable to high-throughput screening.     

Fibronectin and laminin enhance engraftibility of cultured hematopoietic stem cells

To test the hypothesis that extracellular matrix (ECM) components maintain stem cell property, murine bone marrow (BM) cells were expanded in fibronectin and laminin coated plate in the presence of cytokines. We observed significant phenotypic and functional improvement of expanded cells. In 10 days, 800-fold expansion of colony-forming unit-granulocyte erythrocyte monocyte megakaryocyte (CFU-GEMM) was observed in the cultured cells. No apparent activation of cell cycle was observed, but CD29 and very late antigen-4 (VLA-4) expression was increased, as compared to the normal BM cells. A fraction of the expanded cells became verapamil sensitive, suggesting upregulation of multi-drug resistant gene(s), as found in the primitive hematopoietic stem cells (HSCs). Competitive repopulation assay confirmed that HSCs compartment was amplified during culture. Overall, our study clearly demonstrated that ex vivo culture of murine HSCs in the presence of fibronectin and laminin resulted in expansion of primitive stem cells and improvement in the marrow engraftibility.     

Effects of the dual TP receptor antagonist and thromboxane synthase inhibitor EV-077 on human endothelial and vascular smooth muscle cells

The prothrombotic mediator thromboxane A₂ is derived from arachidonic acid metabolism through the cyclooxygenase and thromboxane synthase pathways, and transduces its effect through the thromboxane prostanoid (TP) receptor. The aim of this study was to determine the effect of the TP receptor antagonist and thromboxane synthase inhibitor EV-077 on inflammatory markers in human umbilical vein endothelial cells and on human coronary artery smooth muscle cell proliferation. To this end, mRNA levels of different proinflammatory mediators were studied by real time quantitative PCR, supernatants were analyzed by enzyme immune assay, and cell proliferation was assessed using WST-1. EV-077 significantly decreased mRNA levels of ICAM-1 and PTX3 after TNFα incubation, whereas concentrations of 6-keto PGF1α in supernatants of endothelial cells incubated with TNFα were significantly increased after EV-077 treatment. Although U46619 did not alter coronary artery smooth muscle cell proliferation, this thromboxane mimetic enhanced the proliferation induced by serum, insulin and growth factors, which was significantly inhibited by EV-077. In conclusion, EV-077 inhibited TNFα-induced endothelial inflammation and reduced the enhancement of smooth muscle cell proliferation induced by a thromboxane mimetic, supporting that the thromboxane pathway may be associated with early atherosclerosis in terms of endothelial dysfunction and vascular hypertrophy.     

VEGF189 stimulates endothelial cells proliferation and migration in vitro and up-regulates the expression of Flk-1/KDR mRNA

The vascular endothelial growth factor (VEGF) is a critical factor for development of the vascular system in physiological and pathological angiogenesis. This growth factor exists under at least three isoforms, VEGF120/121, VEGF164/165 and VEGF188/189 which are generated by alternative splicing. VEGF isoforms have different affinities for heparan sulphate as well as for VEGF receptors, and may play distinct roles in vascular development. The role of VEGF189 as an endothelial mitogen, however, remains controversial. VEGF189 is almost entirely bound to the cell surface or extracellular matrix, and is considered active after its cleavage and release from its extracellular binding site. In the present study, we demonstrate that VEGF189 induces endothelial cell proliferation and migration in vitro. The 30-60% increase observed with VEGF189 (10 ng/ml) in HUVEC proliferation was similar to that observed with VEGF165. However, the proliferative effect observed with VEGF189 appeared dependent on the origin of the endothelial cell, since the proliferation was clearly observed with HUVEC but not with BAEC or capillary endothelial cells from dermis (HMEC). The effect of VEGF189 on endothelial cell migration was also analyzed using the wound healing and the Boyden chamber assays. The migration effect was observed with BAEC which do not proliferate with VEGF189, suggesting that different mechanisms are involved in proliferation and migration. In addition, VEGF189 as well as VEGF165 induced a 2-fold increase of Flk-1/KDR expression in HUVEC, the receptor involved in proliferation and migration of endothelial cells. In the Matrigel plug assay in vivo, both VEGF189 and 165 (100 ng/ml) increased the infiltration of endothelial cells. These data suggest that VEGF189 induced endothelial cell migration and proliferation under certain circumstances.     

NG2 proteoglycan increases mesangial cell proliferation and extracellular matrix production

As a membrane-spanning protein, NG2 chondroitin sulfate proteoglycan interacts with molecules on both sides of plasma membrane. The present study explored the role of NG2 in the pathogenesis of diabetic nephropathy. In the normal kidneys, NG2 was observed predominantly in glomerular mesangium, Bowman's capsule and interstitial vessels. Both mRNA and protein expression in kidneys was significantly higher in strepozotocin-induced diabetic rats than that in normal rats. In the cultured rat mesangial cell line HBZY-1, overexpression of NG2 promoted mesangial cell proliferation and extracellular matrix (ECM) production, such as type VI collagen and laminin. Furthermore, target knockdown of NG2 resulted in decreased cell proliferation and ECM formation. The observations suggest that NG2 is up-regulated in diabetic nephropathy. It actively participates in the development and progression of glomerulosclerosis by stimulating proliferation of mesangial cells and deposition of ECM.     

Characterization of porcine arterial endothelial cells cultured on amniotic membrane, a potential matrix for vascular tissue engineering

The existing of basement membrane improves the development of endothelium while constructing blood vessel equivalent. The amniotic membrane (AM) provides a natural basement membrane and has been used in ocular surface reconstruction. This study evaluated the molecular and cellular characteristics of porcine vascular endothelial cells (ECs) cultured on AM. ECs cultured on AM expressed the endothelial marker vWF and exhibited normal endothelial morphology. Here, we demonstrated that AM enhanced the expression of intercellular molecules, platelet-endothelial cell adhesion molecule-1 (PECAM-1), and adhesion molecule VE-cadherin at the intercellular junctions. The expression level of integrin was markedly higher in ECs cultured on AM than on plastic dish. Furthermore, the AM downregulated the expression of E-selectin and P-selectin in both LPS-activated and non-activated ECs. Consistently, adhesion of leukocytes to both activated and non-activated cells was decreased in ECs cultured on AM. Our results suggest that AM is an ideal matrix to develop a functional endothelium in blood vessel equivalent construction.     

Effect of cell culture media on extracellular vesicle secretion from mesenchymal stromal cells and neurons

BackgroundExtracellular vesicles (EVs) secreted by neuronal cells in vitro have promising therapeutic potential for brain diseases. Optimization of cell culture conditions and methodologies for high-yield isolation of EVs for preclinical and clinical applications, however, remains a challenge.ObjectiveTo probe the cell culture conditions required for optimal EV secretion by human-derived neuronal cells.MethodologyFirst, we optimized the EV purification protocol using human mesenchymal stromal cell (MSC) cultures. Next, we compared the effects of different variables in human pluripotent stem cell (hPSC)-derived neuronal cultures on EV secretion. EVs were isolated from cell conditioned media (CCM) and control media with no cells (NCC) using ultrafiltration combined with size-exclusion chromatography (SEC). The hPSC neurons were cultured in 2 different media from which EVs were collected at 2 maturation time-points (days 46 and 60). Stimulation with 25 mM KCl was also evaluated as an activator of EV secretion by neurons. The collected SEC fractions were analyzed by nanoparticle tracking analysis (NTA), protein concentration assay, and blinded transmission electron microscopy (TEM).ResultsA peak in cup-shaped particles was observed in SEC fractions 7–10 of MSC samples, but not corresponding media controls, indicating successful isolation of EVs. Culture medium had no significant effect on EV yield. The EV yield of the samples did not differ significantly according to the culture media used or the cell maturation time-points. Stimulation of neurons with KCl for 3 h reduced rather than increased the EV yield.ConclusionsWe demonstrated successful EV isolation from MSC and neuronal cells using an ultrafiltration-SEC method. The EV yield from MSC and neuronal cultures exhibited a large batch effect, apparently related to the culture media used, highlighting the importance of including NCC as a negative control in all cell culture experiments.     

The effect of elevated extracellular glucose on adherens junction proteins in cultured rat heart endothelial cells

Vascular permeability is a proof of vascular endothelial cell dysfunction induced by diabetes. Vascular permeability is directly related to the width of intercellular endothelial cells junctions, which may become permeable to macromolecules as a result of a change in endothelial cell shape. To determine the role of hyperglycemia in endothelial cell shape, the study examined the effect of high concentrations of glucose on the shape of cultured rat heart endothelial cells. This result indicated that the high-glucose-induced changes in the morphology of endothelial cells, via the glucose-mediated reorganization of F-actin. In endothelial cells, the actin cytoskeleton is tethered to the zonula adherens and focal adhesions, which mediate cell-cell and cell-matrix interactions respectively. The present study demonstrated that the high-glucose-induced changes in the actin-binding protein such as filamin, zonula adherens proteins such as alpha-, beta-, and gamma-catenin, focal adhesions proteins such as focal adhesion kinase, paxillin, and tyrosine phosphorylation of paxillin. It appears that differences in expression of adherens junctions molecules on rat heart endothelial cells in response to high glucose reflect endothelial glucose toxicity, which may also induce endothelial dysfunction in diabetes.     

Atorvastatin induces tissue transglutaminase in human endothelial cells

Tissue transglutaminase (tTgase) contributes to the organisation of the basement membrane and is therefore thought to be important for the integrity and stability of the vessel wall. In the present study, we hypothesised that the HMG-CoA reductase inhibitor atorvastatin may up-regulate the tTgase expression in endothelial cells and thereby exert beneficial effects on endothelial function. Treatment of human umbilical vein endothelial cells (HUVEC) with atorvastatin (1-10 microM) caused a clear increased expression of tTgase in both permeabilised and non-permeabilised HUVEC. In contrast, stimulation of HUVEC with TNFalpha had no substantial effect on tTgase expression or localisation but inhibited the atorvastatin-induced up-regulation and externalisation of tTgase. Propidium iodide staining revealed that statin-induced apoptosis is not responsible for the enhanced expression. By inducing the expression of tTgase, statins may promote tTgase-mediated stabilisation of the basement membrane. This effect of atorvastatin may contribute to the beneficial role of statins on endothelial function.     

Breast cancer cell behaviors on staged tumorigenesis-mimicking matrices derived from tumor cells at various malignant stages

Extracellular matrix (ECM) has been focused to understand tumor progression in addition to the genetic mutation of cancer cells. Here, we prepared “staged tumorigenesis-mimicking matrices” which mimic in vivo ECM in tumor tissue at each malignant stage to understand the roles of ECM in tumor progression. Breast tumor cells, MDA-MB-231 (invasive), MCF-7 (non-invasive), and MCF-10A (benign) cells, were cultured to form their own ECM beneath the cells and formed ECM was prepared as staged tumorigenesis-mimicking matrices by decellularization treatment. Cells showed weak attachment on the matrices derived from MDA-MB-231 cancer cells. The proliferations of MDA-MB-231 and MCF-7 was promoted on the matrices derived from MDA-MB-231 cancer cells whereas MCF-10A cell proliferation was not promoted. MCF-10A cell proliferation was promoted on the matrices derived from MCF-10A cells. Chemoresistance of MDA-MB-231 cells against 5-fluorouracil increased on only matrices derived from MDA-MB-231 cells. Our results showed that the cells showed different behaviors on staged tumorigenesis-mimicking matrices according to the malignancy of cell sources for ECM preparation. Therefore, staged tumorigenesis-mimicking matrices might be a useful in vitro ECM models to investigate the roles of ECM in tumor progression.     

siRNA干扰TCAB1对人主动脉平滑肌增殖的影响及机制

目的:探究TCAB1沉默对人主动脉平滑肌细胞(HASMC)增殖的影响及可能机制。方法:采用RNAi技术设计并合成靶向沉默TCAB1基因表达的三对特异性si RNA序列(si TCAB1-331、si TCAB1-619、si TCAB-749)和一对阴性对照序列(NC),使用lipo2000将si TCAB1、NC转染HASMC,分为3个组:干扰组(si TCAB1)、空白对照组(BC)、阴性对照组(NC),转染24小时倒置荧光显微镜观察细胞转染情况;通过RT-qPCR和Western blot从3个干扰靶点中筛选效果最好的干扰靶点。进一步转染si TCAB1-749后,MTS检测HASMC 24、48、72 h的增殖能力,48小时用RT-qPCR和Western blot检测CyclinD1表达量变化,流式细胞术检测HASMC的细胞周期变化。结果:RT-qPCR和WB结果显示si TCAB1-749为最好的干扰靶点;转染24、48、72 h后,si TCAB1-749组增殖水平明显低于NC组、BC组(P0.05)。流式结果显示:si TCAB1-749组处于G1期细胞比率有所增加,处于S期细胞比率减少(P0.05),且si TCAB1-749组细胞周期蛋白cyclinD1表达也下降(P0.05)。结论:沉默TCAB1能抑制HASMC的增殖,其机制可能与阻碍细胞周期蛋白cyclinD1有关。     

Morphogenetic and neuronal characterization of human neuroblastoma multicellular spheroids cultured under undifferentiated and all-trans-retinoic acid-differentiated conditions

In this study, we aimed to compare the morphogenetic and neuronal characteristics between monolayer cells and spheroids. For this purpose, we established spheroid formation by growing SH-SY5Y cells on the hydrophobic surfaces of thermally-collapsed elastin-like polypeptide. After 4 days of culture, the relative proliferation of the cells within spheroids was approximately 92% of the values for monolayer cultures. As measured by quantitative assays for mRNA and protein expressions, the production of synaptophysin and neuronspecific enolase (NSE) as well as the contents of cell adhesion molecules (CAMs) and extracellular matrix (ECM) proteins are much higher in spheroids than in monolayer cells. Under the all-trans-retinoic acid (RA)-induced differentiation condition, spheroids extended neurites and further up-regulated the expression of synaptophysin, NSE, CAMs, and ECM proteins. Our data indicate that RA-differentiated SH-SY5Y neurospheroids are functionally matured neuronal architectures. [BMB Reports 2013; 46(5): 276-281]     

Simvastatin modulates TNFalpha-induced adhesion molecules expression in human endothelial cells

Adhesion and transendothelial migration of leukocytes into the vascular wall is a crucial step in atherogenesis. Expression of cell adhesion molecules by endothelial cells plays a leading role in this process. We investigated the effect of simvastatin, an inhibitor of HMG-CoA reductase administered to reduce plasma levels of LDL-cholesterol, on the expression of vascular cell adhesion molecule-1 (VCAM-1) and intracellular cell adhesion molecule-1 (ICAM-1) by human umbilical vein endothelial cells (HUVEC) stimulated with tumor necrosis factor alpha (TNFalpha). We found the expression to be significantly inhibited by the drug in a time and concentration-dependent manner and to a greater extent in the case of VCAM-1 as compared with ICAM-1. In TNFalpha-stimulated HUVEC, simvastatin decreased VCAM-1 and ICAM-1 mRNA levels, inhibited TNFalpha-induced activation of nuclear factor kappaB (NF-kappaB) and enhanced expression of peroxisome proliferator-activated receptor alpha (PPARalpha). These effects were associated with reduction of adherence of monocytes and lymphocytes to HUVEC. The present findings suggest that the benefits of statins in vascular disease may include the inhibition of expression of VCAM-1 and ICAM-1 through effects on NF-kappaB.