Endothelium : journal of endothelial cell research最新文献

Statins have been reported to affect blood vessel formation. Thrombospondin-1 (TSP-1) is a multifunctional protein that affects vasculature systems such as platelet activation, angiogenesis, and wound healing. This study was designed to investigate the effect of atorvastatin on TSP-1 synthesis in thrombin-stimulated human umbilical vein endothelial cells (HUVECs), and its regulation by mevalonate or its derivatives. The results showed that atorvastatin down-regulated TSP-1 expression in HUVECs. This effect was fully reversed by mevalonate, farnesylpyrophosphate (FPP), and gerarylgeranylpyrophosphate (GGPP). Furthermore, farnesyltransferase and geranylgeranyltransferase inhibitors decreased TSP-1expression. It was also found that thrombin increased TSP-1 expression in HUVECs. Atorvastatin (0.1, 1, and 10 muM) decreased TSP-1 in thrombin-stimulated cells (45%, 66%, and 80%). Mevalonate partially reversed this inhibitory effect of atorvastatin on TSP-1, whereas the presence of FPP and GGPP did not alter TSP-1. Rho-kinase inhibitor neutralized the up-regulation of TSP-1 induced by thrombin. In conclusion, atorvastatin inhibits TSP-1 expression in endothelial cells via the mevalonate pathway. Rho protein activation is necessary for up-regulation of TSP-1 synthesis induced by thrombin. Because FPP and GGPP are essential for the activity of Rho proteins, inhibition of these proteins may constitute the mechanism by which atorvastatin inhibits thrombin up-regulated TSP-1 expression.

The authors hypothesized that matrix metalloproteinase (MMP)-2, MMP-9, tissue inhibitor of metalloproteinase (TIMP)-1, and TIMP-2 would be abnormal in acute coronary syndromes (ACS). Forty-six diabetic and 78 nondiabetic patients during ACS and after 3 months were enrolled in this study. MMP-2, -9 and TIMP-1, -2 plasma levels were measured. Significant decrease of MMP-2, TIMP-1, and TIMP-2 plasma levels was observed in the nondiabetic group with ACS after 3 months compared to the baseline value. Significant decrease of MMP-2, MMP-9, TIMP-1, and TIMP-2 plasma levels was observed in the diabetic group with ACS after 3 months compared to the baseline value. MMP-9, TIMP-1, and TIMP-2 plasma levels were higher in diabetic patients during ACS compared to nondiabetic patients during ACS. TIMP-1 and TIMP-2 increases were observed in diabetic patients with ACS at 3 months compared to nondiabetic patients after ACS. MMPs and TIMP-1 and -2 plasma levels were alterated in nondiabetic and diabetic patients during ACS and after 3 months, which may reflect abnormal extracellular matrix metabolism in diabetes during and after acute event.

Endothelial connexins have been linked to atherosclerosis and hypertension; however, little is know about their sensitivity to stimuli and individual functions. This study investigates the responses of endothelial connexin 37, connexin 40, and connexin 43 (Cx37, Cx40, and Cx43) to shear stress and substrate. Human endothelial cells were seeded on adsorbed collagen or a collagen gel containing smooth muscle cells and exposed to static or laminar shear stress. Connexin mRNA, protein, and gap junction communication were examined. Endothelial monolayers were treated with connexin-specific short interfering RNA (siRNA) and evaluated for communication, proliferation, and morphology under static and shear stress. Results show differential responses of Cx37, Cx40, and Cx43 to substrate and shear stress with reduced communication after shear exposure. RNA interference of individual connexins resulted in expression change of nontarget connexins, which suggests linked expression. Gap junction communication under static conditions is reduced following Cx43 siRNA treatment. Endothelial cells are more elongated with RNA interference (RNAi) targeting Cx40. In conclusion, endothelial connexins demonstrated novel sensitivity to mechanical environment and substrate. Individual isotypes show differential responses and RNAi knockdown provides new insight into connexin function and potential roles in the vasculature.

To detect endothelial progenitor cells in human umbilical veins and isolated endothelial cells, the authors examined protein and mRNA expression levels of cell surface markers for endothelial progenitor cells in human umbilical veins before and after trypsin treatment and at different passages of the isolated endothelial cells. CD133(+) (2.14 +/- 0.57 per mm) and KDR(+) (35.74 +/- 8.28 per mm) cells were observed in the intima of umbilical veins. The amounts of CD133(+), KDR(+), CD34(+), and CD105(+) cells decreased in the intima after trypsin treatment, whereas the percent of CD133(+) and KDR(+)cells in the media did not change significantly. Moreover, similar protein and mRNA expression levels of CD133 and KDR were detected in the umbilical veins before and after trypsin treatment. In the isolated cells from umbilical veins, the percent of CD133(+) and CD34(+) cells in P1 was 3.43% +/- 3.85%, which was higher than those in P3 (0.17% +/- 0.21%, p = 0.005) and P6 (0.14% +/- 0.18%, p = .001). The mRNA expression levels of CD133 and CD105 were down-regulated in later passages compared to those in P1, whereas the expression level of KDR was up-regulated in late passages. Thus it is suggested that endothelial progenitor cells reside in the distinct zone (e.g., initma and media) of human umbilical veins, and retain the capacity of differentiation to endothelial cells in vitro.

Mental stress has been shown to impair endothelium-dependent vasodilation (EDV) in the human forearm. The aim of this study was to investigate if this response could be blunted by local infusions of beta-blockade (propranolol), alpha-blockade (phentolamine), or neurogenic blockade. Thirty-one young healthy volunteers underwent forearm blood flow (FBF) measurements, using venous occlusion plethysmography, during local intra-arterial infusions of metacholine (MCh; inducing EDV) and sodium nitroprussid (SNP; inducing endothelial-independent vasodilation [EIDV]), respectively. These measurements were repeated during a 5-min mental arithmetic stress test without (n = 8) or with concomitant local infusion of propranolol (n = 7) or phentolamine (n = 8) in the forearm or during axillary plexus blockade (n = 8). An index of endothelial vasodilatory function (EFI) was calculated as the EDV to EIDV ratio. Mental stress impaired EDV significantly (p < .05), and as a result, EFI was significantly reduced (p = .02). This effect on EFI could be blocked by propranolol and neurogenic blockade but not by phentolamine (p < .05). Thus, impairment of endothelial vasodilatory function induced by mental stress could be blocked by beta-adrenergic, but not alpha-adrenergic, receptor blockade.

Isolation of endothelial progenitors from human umbilical cord blood generated great hope in vascular tissue engineering. However, before clinical use, progenitor derived endothelial cells (PDECs) have to be compared with mature endothelial cells (ECs). The aim of this study was to explore the behavior of PDECs exposed to a proinflammatory cytokine (interleukin-1alpha; IL-1alpha) according to the mitogen-activated protein (MAP) kinase and nuclear factor (NF)-kappaB signal transduction pathways as well as procoagulant activity (PCA). CD34(+) mononuclear cells were isolated using magnetic beads, cultured, and compared with human saphenous vein ECs (HSVECs). PDECs express endothelial markers: CD31, VE-cadherin, von Willebrand factor, KDR, and incorporate acetylated low-density lipoprotein (Dil-Ac-LDL). IL-1alpha similarly activates c-Jun N-terminal protein kinase (JNK) and p38 pathways in HSVECs and PDECs, whereas extracellular signal-related kinase (ERK)1/2 phosphorylation is lower in PDECs than in HSVECs. Low ERK1/2 phosphorylation in PDECs was specific to IL-1alpha as vascular endothelial growth factor (VEGF) similarly stimulated ERK1/2 pathway. With respect to inhibitor of NF-kappa B (Ikappa B) degradation, NF-kappa B translocation and phosphorylation, the NF-kappa B pathway is comparable in HSVECs and PDECs after stimulation. PCA and tissue factor level induced by IL-1alpha are lower in PDECs than in HSVECs. Thus, our data show that PDECs display the characteristics of functional mature ECs under IL-1alpha stimulation. However, we observed significant differences between PDECs and HSVECs related to both ERK1/2 pathway activation and tissue factor production.

In 1983, Harold Dvorak and his colleagues were the first to show that tumor cells secreted vascular permeability factor (VPF) and that a blocking antibody to VPF could prevent the edema and fluid accumulation that is characteristic of human cancers. In 1986, Dvorak went on to demonstrate that VPF was secreted by a variety of human tumor cell lines and proposed that VPF was in part responsible for the abnormal vasculature seen in human tumors. As a result, he and other investigators demonstrated that VPF was capable of stimulating endothelial cell growth and angiogenesis. These fundamental discoveries led to additional research conducted by Napoleone Ferrara and his laboratory, confirming the cloning of VPF and renaming the protein vascular endothelial growth factor (VEGF). In 1986, Dvorak proposed that by secreting VPF, tumors induce angiogenesis by turning on the wound healing response. He noted that wounds, like tumors, secrete VPF, causing blood vessels to leak plasma fibrinogen, which stimulates blood vessel growth and provides a matrix on which they can spread. Unlike wounds, however, that turn off VPF production after healing, tumors did not turn off their VPF production and instead continued to make large amounts of VPF, allowing malignant cells to continue to induce new blood vessels and so to grow and spread. Thus, tumors behave like wounds that fail to heal. This work is again extremely significant for patients worldwide, as Dvorak's scientific research is leading his colleagues all over the world to examine how to treat a tumor through its blood supply.

Hyperhomocysteinemia is widely recognized as an independent risk factor for coronary artery vascular disease, although the underlying mechanisms are not well understood. This study aims to investigate the effect of homocysteine on nitric oxide (NO) production in coronary microvascular endothelial cells (CMECs) and putative mechanisms mediating this effect. CMECs were isolated on Langendorff system by collagenase perfusion of hearts from male rats and cultured. The effect of homocysteine (0.01 to 1 mM) on basal and stimulated NO production was evaluated by measuring nitrite in the culture media after incubation with or without N(G)-nitro-L-arginine methyl ester (L-NAME) (1 mM), superoxide dismutase (100 U/mL), or catalase (1000 U/mL) for 24 h. Total nitrite was measured using Griess reaction after reduction of nitrate to nitrite with nitrate reductase. Homocysteine did not affect basal nitrite accumulation; however, it significantly increased the nitrite accumulation induced by the calcium ionophore A23187 or interleukin-1beta only at 1 mM. This effect of homocysteine was significantly inhibited by L-NAME, superoxide dismutase, and catalase. In conclusion, homocysteine increases NO release from stimulated CMECs without affecting basal NO production, which is probably accompanied by increased production of reactive oxygen species. It can be postulated that endothelial cells generate NO in order to minimize the damage caused by homocysteine.

It has been postulated that ischemic stroke due to acute cocaine usage involves constriction of the cerebral vasculature. However, the mechanism underlying the constriction remains unclear. This study tested whether cocaine constriction was mediated via endothelin-1. Cocaine suffusion induced maintained constriction in the rabbit basilar artery in situ. The constriction was relaxed by PD145065, an endothelin A and B receptor antagonist. These results support the hypothesis that constriction of the cerebral vasculature due to acute cocaine exposure is via endothelin-1 release. Endothelin receptor antagonists may be of therapeutic benefit in cerebrovascular pathophysiologies involving cocaine constriction.

Loss of endothelial cells (ECs) with ensuing exposure of thrombogenic subendothelial surface is a common cause of thromboembolic complications in atherosclerotic arteries. Thus, endothelial denudation has emerged as a major contributor to the pathogenesis of atherosclerosis and its complications. Despite ongoing efforts in elucidating the pathogenesis of endothelial erosions in human atherosclerotic arteries, the mechanisms of erosion have remained enigmatic, partly due to lack of well-established methods for its identification. Here the authors point out plausible pitfalls in the current methodology and provide an improved immunohistochemical method for identifying endothelial erosion; i.e., immunofluorescence double staining with antibodies against CD42b and CD31/CD34. This method enables reliable detection of ECs and platelets in the same staining by allowing detection of "pseudoendothelium" caused by CD31 staining of a thin platelet layer covering sites of endothelial erosion. As erosion with a luminal platelet thrombus is likely to represent an in vivo erosion, and erosion without platelets an ex vivo artefact, the method makes it possible to exclude artefactual erosions resulting from sample processing. The novel immunostaining protocol presented here allows more reliable detection of endothelial erosions and so may facilitate studies on the mechanisms involved in the pathogenesis of plaque erosion and acute coronary syndromes.