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Adrenomedullin as a Novel Antimigration Factor of Vascular Smooth Muscle Cells

The present study investigated the effect of adrenomedullin, a novel vasorelaxant peptide, on the migration of cultured rat vascular smooth muscle cells (SMCs) by using the Boyden-chamber method. Fetal calf serum (FCS) and platelet-derived growth factor (PDGF)–BB strongly stimulated SMC migration. Adrenomedullin clearly inhibited SMC migration stimulated with 5% and 10% FCS in a concentration-dependent manner. The migration induced by 10 and 25 ng/mL PDGF-BB was also inhibited by adrenomedullin in a concentration-dependent manner. Inhibition by adrenomedullin of FCS- and PDGF-induced SMC migration was paralleled by an increase in the cellular level of cAMP. In fact, the percent increase in cAMP level was strongly correlated with the percent decrease in migration activity of SMCs after treatment with adrenomedullin. 8-Bromo cAMP, a cAMP analogue, reproduced the inhibition by adrenomedullin of FCS- and PDGF-induced SMC migration. An activator of adenylate cyclase, forskolin, also reduced FCS- and PDGF-induced SMC migration. These data indicate that adrenomedullin inhibits the migration of SMCs stimulated with FCS and PDGF, probably through a cAMP-dependent process. On the basis of these results and the finding that adrenomedullin is synthesized in and secreted from vascular endothelial cells, adrenomedullin may play a role as a local antimigration factor in some pathophysiological states.

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Antioxidants Improve Impaired Insulin-Mediated Glucose Uptake and Prevent Migration and Proliferation of Cultured Rabbit Coronary Smooth Muscle Cells Induced by High Glucose

Background—To explore the role of intracellular oxidative stress in high glucose–induced atherogenesis, we examined the effect of probucol and/or α-tocopherol on the migration and growth characteristics of cultured rabbit coronary vascular smooth muscle cells (VSMCs).

Methods and Results—Chronic high-glucose-medium (22.2 mmol/L) treatment increased platelet-derived growth factor (PDGF)-BB–mediated VSMC migration, [3H]thymidine incorporation, and cell number compared with VSMCs treated with normal-glucose medium (5.6 mmol/L+16.6 mmol/L mannose). Probucol and α-tocopherol significantly suppressed high glucose–induced increase in VSMC migration, cell number, and [3H]thymidine incorporation. Probucol and α-tocopherol suppressed high glucose–induced elevation of the cytosolic ratio of NADH/NAD+, phospholipase D, and membrane-bound protein kinase C activation. Probucol, α-tocopherol, and calphostin C improved the high glucose–induced suppression of insulin-mediated [3H]deoxyglucose uptake. Chronic high-glucose treatment increased the oxidative stress, which was significantly suppressed by probucol, α-tocopherol, suramin, and calphostin C.

Conclusions—These findings suggest that probucol and α-tocopherol may suppress high glucose–induced VSMC migration and proliferation via suppression of increases in the cytosolic ratio of free NADH/NAD+, phospholipase D, and protein kinase C activation induced by high glucose, which result in reduction in intracellular oxidative stress.

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An improved method for the quantitation of cellular migration: Role of αvβ3 integrin in endothelial and smooth muscle cell migration

The present study was undertaken to develop a simple and improvedmethod for the accurate quantitation of cellular migration and to examinethe role of agrvbeta3 integrins in different cellular migration. Using our newly developed micro-volume chemotaxis assay, we developed an improved quantitative method to measure in vitro chemotaxis of smooth muscle or endothelial cells toward different extracellular matrix proteins. The convenience in setup and counting of migrated cells using this method allows for large capacity screening and for various research applications with other cells as well. The signal to noise ratios were in the range of 10/1, along with about 10–20% intra- or inter-assay variabilities. Using this method, we have determined that either vitronectin at 0.4 µg/well or osteopontin at 0.4 µg/well are selective agrvbeta3 chemoattractants for endothelial or smooth muscle cells (0.5 × 105 cells/well). Additionally, a selective agrvbeta3 small molecule peptiddomimetic, monoclonal antibody LM609, or an anti-beta3 (agrvbeta3/agrIIbeta3) anti-body, c7E3 demonstrated maximal inhibition of cellular migration toward vitronectin or osteopontin. These data suggest the potential utility of this method in assessing the role of various mechanisms in cellular migration and also suggests the potential implication of an agrvbeta3 antagonist in blocking pathological processes involving endothelial or smooth muscle cell adhesion/migration.

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HMG-CoA Reductase Inhibitors Prevent Migration of Human Coronary Smooth Muscle Cells Through Suppression of Increase in Oxidative Stress

In vitro and in vivo evidence of a decrease in vascular smooth muscle cell (SMC) migration induced by 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors has been reported. When added to SMC cultures for 6 hours, the HMG-CoA reductase inhibitors fluvastatin, simvastatin, and pravastatin at 1 μmol/L resulted in a 48%, 50%, and 16% suppression, respectively, of human coronary SMC migration; these reductions mirrored the suppression in oxidative stress induced by 1 μmol/L lysophosphatidylcholine (lyso-PC) of 50%, 53% and 19%, respectively. The hydroxylated metabolites of fluvastatin, M2 and M3, at 1 μmol/L also suppressed the enhancement of SMC migration by 58% and 45% and the increase in oxidative stress induced by lyso-PC of 58% and 49%, respectively. Lyso-PC activated phospholipase D and protein kinase C (PKC), and this activation was also suppressed by HMG-CoA reductase inhibitors. The inhibition of phospholipase D and PKC was reversed by 100 μmol/L mevalonate, its isoprenoid derivative, farnesol, and geranylgeraniol but not by 10 μmol/L squalene. Antisense oligodeoxynucleotides at 5 μmol/L to PKC-α, but not those to the PKC-β isoform, suppressed the lyso-PC–mediated increases in SMC migration and oxidative stress. These findings suggest that HMG-CoA reductase inhibitors have direct antimigratory effects on the vascular wall beyond their effects on plasma lipids and that they might exert such antimigratory effects via suppression of the phospholipase D– and PKC (possibly PKC-α)-induced increase in oxidative stress, which might in turn prevent significant coronary artery disease.

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Adenoviral Gene Transfer of Fortilin Attenuates Neointima Formation Through Suppression of Vascular Smooth Muscle Cell Proliferation and Migration

Fortilin, a recently characterized nuclear antiapoptotic factor structurally distinct from inhibitor of apoptosis proteins (IAPs) and Bcl-2 family member proteins, has been suggested to be involved in cell survival and regulation of apoptosis within the cardiovascular system. In this continued investigation, we characterized the influence of adenovirus-mediated fortilin (Ad-fortilin) gene delivery on vascular remodeling after experimental angioplasty.

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Leptin Stimulates Rat Aortic Smooth Muscle Cell Proliferation and Migration

Leptin, a peptide secreted from adipose tissue, plays an important role in the regulation of food intake and energy expenditure. In obese patients, plasma leptin levels are elevated and obesity is one of the major risk factors for cardiovascular diseases. Therefore, in this study, we investigated the effect of leptin on vascular smooth muscle cell (VSMC) functions. Cultured rat aortic VSMC expressed 130-kDa short form of leptin receptor. Leptin stimulated both proliferation and migration of VSMC. Leptin stimulated phosphorylation and activation of mitogen-activated protein (MAP) kinases, and also increased phosphatidylinositol (PI) 3-kinase activity. Further, two distinct PI 3-kinase inhibitors, wortmannin and LY294002 inhibited the migratory effect of leptin. These results demonstrate that leptin is a proliferative and migratory factor for VSMC, implying that leptin may play a role in the formation and development of vascular lesions.

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