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Endothelial Monolayer (endothelial + monolayer)
Selected AbstractsEndothelial Progenitor Cells: A Promising Therapeutic Alternative for Cardiovascular DiseaseJOURNAL OF INTERVENTIONAL CARDIOLOGY, Issue 2 2007CHUNMING DONG The integrity and functional activity of the endothelial monolayer play a critical role in preventing atherosclerotic disease progression. Endothelial cell (EC) damage by atherosclerosis risk factors can result in EC apoptosis with loss of the integrity of the endothelium. Thus, approaches to repair the injured vessels with the goal of regenerating ECs have been tested in preclinical experimental models and in clinical studies. Indeed, endothelial progenitor cells (EPCs) originating from the bone marrow have been shown to incorporate into sites of neovascularization and home to sites of endothelial denudation. These cells may provide an endogenous repair mechanism to counteract ongoing risk factor-induced endothelial injury and to replace dysfunctional endothelium. Risk factors for coronary artery disease, such as age, smoking, hypertension, hyperlipidemia, and diabetes, however, reduce the number and functional activity of circulating EPCs, potentially restricting the therapeutic prospective of progenitor cells and limiting the regenerative capacity. Furthermore, the impairment of EPCs by risk factors may contribute to atherogenesis and atherosclerotic disease progression. The article reviews the role of EPCs in atherogenesis and in predicting cardiovascular outcomes, and highlights the potential challenges in developing therapeutic strategies aiming to interfere with the balance of injury and repair mechanisms. [source] Chlamydia pneumoniae infection promotes the transmigration of monocytes through human brain endothelial cellsJOURNAL OF NEUROSCIENCE RESEARCH, Issue 5 2003A. MacIntyre Abstract We have investigated the effects of Chlamydia pneumoniae on human brain endothelial cells (HBMECs) and human monocytes as a mechanism for breaching the blood-brain barrier (BBB) in Alzheimer's disease (AD). HBMECs and peripheral blood monocytes may be key components in controlling the entry of C. pneumoniae into the human brain. Our results indicate that C. pneumoniae infects blood vessels and monocytes in AD brain tissues compared with normal brain tissue. C. pneumoniae infection stimulates transendothelial entry of monocytes through HBMECs. This entry is facilitated by the up-regulation of VCAM-1 and ICAM-1 on HBMECs and a corresponding increase of LFA-1, VLA-4, and MAC-1 on monocytes. C. pneumoniae infection in HBMECs and THP-1 monocytes up-regulates monocyte transmigration threefold in an in vitro brain endothelial monolayer. In this way, C. pneumoniae infection in these cell types may contribute to increased monocyte migration and promote inflammation within the CNS resulting from infection at the level of the vasculature. Thus, infection at the level of the vasculature may be a key initiating factor in the pathogenesis of neurodegenerative diseases such as sporadic AD. © 2002 Wiley-Liss, Inc. [source] Circulating Endothelial Progenitor Cells After Kidney TransplantationAMERICAN JOURNAL OF TRANSPLANTATION, Issue 9 2005María José Soler Circulating endothelial progenitor cells (EPCs) promote vascular repair and maintain integrity of the endothelial monolayer. Reduced EPCs number has been associated with endothelial dysfunction in various cardiovascular diseases. Cardiovascular disease risk is higher in renal transplant patients (RT) than the general population. We studied EPCs number and proliferation in RT, and examined the association with other cardiovascular risk factors such as reduced glomerular filtration rate (GFR) and LDL cholesterol. EPCs concentration was determined in 94 RT and 39 control subjects (C) by flow cytometry. EPCs proliferation was also studied after 7 days in culture. EPCs concentration was significantly reduced in RT versus C (median 33.5 [5,177] vs. 53 [9,257] EPCs/105 PMN cells, p = 0.006). EPCs proliferation was also reduced in RT versus C (mean ± SD; 372.7 ± 229.3 vs. 539.8 ± 291.3 EPCs × field, p = 0.003). In multiple regression analysis, GFR, HDL, LDL and body weight were independent predictors of EPCs concentration in RT (r2= 0.25, p < 0.001). EPCs number is reduced in RT, particularly in patients with reduced GFR. Moreover, EPCs from RT studied in vitro, showed reduced proliferation, which is a sign of functional impairment. These alterations may be involved in increased cardiovascular risk of RT. [source] Gene therapy: can we prevent/modulate apoptosis in EC?ACTA OPHTHALMOLOGICA, Issue 2009T FUCHSLUGER Purpose Regardless of the inciting cause, CEC loss is a common denominator of corneal graft failure. CEC loss during storage results in significant loss of suitable tissue for grafting, CEC loss after transplantation is a major cause of graft failure. The purpose of this study is to investigate the role of apoptosis in CEC in order to prevent CEC loss during storage. Methods Gene transfer of Lenti-Bcl-xL or ,p35 was accomplished in human donor corneas, primary cultured CEC and an immortalized CEC line and compared to untreated controls. Cell death (apoptosis) was induced by Actinomycin or Etoposide (external vs. internal apoptotic pathway, respectively). In addition, CEC loss during preservation was studied both during Optisol GS (4C) and organ culture storage (37C, Biochrome Medium I). Both storage media were diluted with PBS to promote cell loss. CEC were enumerated, apoptosis was detected by TUNEL staining and confocal microscopy. Results The percentage of TUNEL-positive CEC provoked by the apoptotic inducers was significantly reduced relative to controls. Transfected corneas preserved an almost intact endothelial monolayer while controls nearly entirely lost vital CEC. During long-term storage experiments at 4C and at 37C, CEC counts in corneas expressing anti-apoptotic genes remained significantly higher compared to the controls. Conclusion Protection of CEC by anti-apoptotic genes appears to be an effective method to reduce CEC loss during storage. The application of this technique could increase the amount of high quality grafts in eye banking and further reduce graft failure following corneal transplantation, and is be of specific interest as to precut corneas and DSAEK procedures. [source] Gene transfer to ovine corneal endotheliumCLINICAL & EXPERIMENTAL OPHTHALMOLOGY, Issue 5 2001Sonja Klebe MBBS ABSTRACT Purpose: Modification of a donor cornea by gene therapy has potential to modulate irreversible rejection, the major cause of corneal graft failure. The sheep is a useful model for the human in this respect, as ovine endothelial cells are amitotic. The aim of the study was to investigate the ability of various non-viral and viral agents to transfer a reporter gene to ovine corneal endothelium. Methods: The non-viral agents Transfectin-10, Transfectin-20, Transfectin-50, SuperFect, Effectene and CLONfectin were used to deliver the reporter gene, Escherichia coli lacZ, to ovine corneal endothelium in vitro. A Herpes simplex virus-1 and an adenoviral vector each encoding E. coli lacZ were similarly tested. Infected corneas were organ-cultured for up to 7 days in vitro to allow transfection efficiency, duration of gene expression and toxicity attributable to each vector to be compared. Results: Scattered single or clusters of endothelial cells expressing the reporter gene were observed after transfection with CLONfectin, Transfectin-10, Transfectin-20 and Transfectin-50. SuperFect and Effectene were virtually in-effective. At best, the absolute number of infected cells per endothelial monolayer after 3 or 7 days of organ culture was estimated as < 0.01%. The Herpes simplex virus-1 vector also failed to transduce ovine corneal endothelium efficiently. In contrast, transfection rates of up to 70% of endothelial cells were observed with the adenoviral vector. Conclusion: Non-viral vectors and Herpes simplex virus-1 are unlikely to be suitable for gene therapy of corneal endothelium, because the efficiency of transfection is low compared with the rates achieved with adenoviral vectors. [source] The p110, Isoform of PI3K Differentially Regulates ,1 and ,2 Integrin-Mediated Monocyte Adhesion and Spreading and Modulates DiapedesisMICROCIRCULATION, Issue 6 2006ALEXANDER M. FERREIRA ABSTRACT Objective: Leukocyte diapedesis is misregulated in inflammatory disease and depends on the binding of monocytic LFA-1 and VLA-4 to endothelial ICAM-1 and VCAM-1, respectively. The authors hypothesized that these different molecular interactions elicit specific signaling cascades within monocytes regulating specific steps in adhesion, motility, and diapedesis. Methods: The authors employed the PI3K p110, catalytic subunit specific inhibitor IC87114 (2 , M) and the broad-spectrum PI3K inhibitory agents LY294002 (50 , M) and wortmannin (100 nM), to examine the role of PI3K, in monocyte diapedesis through endothelial monolayers and its role in monocyte adhesion and spreading upon carpets of ICAM-1 or VCAM-1. They further explored the effects of PI3K, inhibition on the activation state of , 1 and , 2 integrins with immunocytochemistry and flow cytometry. Results: In human peripheral blood monocytes IC87114 was as effective as wortmannin and LY294002 at inhibiting diapedesis, however, in THP-1 cells LY294002 and wortmannin caused a 5-fold reduction in diapedesis, while IC87114 only decreased diapedesis 2-fold. PI3K, activity was specifically required for THP-1 cell adhesion and spreading on VCAM-1, but not on ICAM-1 protein substrates. Flow cytometric analysis demonstrated that PI3K, inhibition decreased the amount of conformationally active , 1-integrins, while having no effect on the prevalence of conformationally active , 2-integrins expressed on the cell surface. In addition, PI3K, inhibition resulted in a 4-fold decrease in the activation state of Rac-1 and Cdc42. Conclusions: These results demonstrate the specific necessity of PI3K, in regulating monocytic integrin activation and the general role of PI3K signaling during diapedesis, implicating PI3K as a target for therapeutic intervention. [source] Signal Transduction Pathways in Enhanced Microvascular PermeabilityMICROCIRCULATION, Issue 6 2000SARAH Y. YUAN ABSTRACT We have been investigating the molecular mechanisms underlying pathophysiological regulation of microvascular permeability on isolated venules and cultured venular endothelial monolayers. Physiological approaches have been employed in combination with molecular analyses to probe the signal transduction pathways leading to enhanced microvascular permeability. A newly developed technique of protein transfection into cells and intact microvessels enables the correlation of functional reactions and signaling events at the molecular level in a direct and specific fashion. The results indicate that inflammatory mediators increase microvascular permeability via intracellular signaling pathways involving the activation of phospholipase C, cytosolic calcium, protein kinase C, nitric oxide synthase, guanylate cyclase, and protein kinase G. In response to the signaling stimulation, complex biochemical and conformational reactions occur at the endothelial structural proteins. Specifically, myosin light-chain activation-mediated myosin light-chain phosphorylation can result in cell contraction. VE-cadherin and ,-catenin phosphorylation may induce dissociation of the junctional proteins and their connection to the cytoskeleton, leading to a loose or opened intercellular junction. Focal adhesion phosphorylation and redistribution further provide an anchorage support for the conformational changes in the cells and at the cell junction. The three processes may act in concert to facilitate the flux of fluid and macromolecules across the microvascular endothelium. [source] HIGH GLUCOSE-INDUCED HUMAN UMBILICAL VEIN ENDOTHELIAL CELL HYPERPERMEABILITY IS DEPENDENT ON PROTEIN KINASE C ACTIVATION AND INDEPENDENT OF THE Ca2+,NITRIC OXIDE SIGNALLING PATHWAYCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 9 2005Lei Dang SUMMARY 1.,Endothelial barrier dysfunction plays a pivotal role in the pathogenesis of diabetic vascular complications. The precise molecular mechanisms by which hyperglycaemia causes the increased permeability in endothelial cells are not yet well understood. In the present study, we investigated whether high concentrations of glucose induce endothelial permeability through the activation of protein kinase C (PKC) and/or the calcium,nitric oxide (NO) signalling pathway in human umbilical vein endothelial cells (HUVEC). 2.,Endothelial permeability was measured by albumin diffusion across endothelial monolayers under the stimuli of high glucose (HG; 20 mmol/L), 100 nmol/L phorbol-myristate-acetate (PMA) or 100 nmol/L histamine. The intracellular calcium concentration ([Ca2+]i) was detected in HUVEC using the fluorescent probe fura-2 AM. The effects of PKC inhibitors (LY379196 and hypocrellin A) and the NO synthase (NOS) inhibitor NG -monomethyl- l -arginine (l -NMMA) on endothelial permeability and [Ca2+]i were determined. 3.,High glucose and PMA increased endothelial permeability associated with decreased [Ca2+]i, whereas histamine triggered significant increases in endothelial permeability, accompanied by increases in [Ca2+]i in HUVEC. Hypocrellin A (HA) and LY379196 reversed both HG- and histamine-induced endothelial permeability. The NOS inhibitor l -NMMA only abolished histamine- and not HG-induced endothelial permeability. Neither LY379196, HA nor l -NMMA had any significant effects on alterations in [Ca2+]i caused by HG and histamine. 4.,These results indicate that increased endothelial permeability in HUVEC induced by HG is dependent on PKC activity and is independent of the [Ca2+]i,NO pathway. Increased endothelial permeability due to other inflammatory factors, such as histamine, may also be mediated by the PKC pathway. Thus, PKC inhibitors would be a potential therapeutic approach to endothelial dysfunction induced by hyperglycaemia, as well as other inflammatory factors, in diabetes. [source] | ||||||||||