Femoral Artery Wire Injury Research Articles

Abstract 3373: MRP-8/14 is Critical for the Biological Response to Vascular Injury

Background : MRP-8 (S100A8) and MRP-14 (S100A9) are members of the S100-family of calcium-modulated proteins that regulate myeloid cell function and control inflammation, in part, through activation of toll-like receptor-4 and RAGE. Using a transcriptional profiling approach in patients with acute coronary syndromes, we made the novel discovery that MRP-14 is associated with atherothrombosis, and demonstrated that elevated plasma levels of MRP-8/14 heterodimer predict increased risk of first and recurrent cardiovascular events. Despite functioning as a pro-inflammatory mediator, the role of MRP-8/14 in vascular inflammation and disease are unknown. Methods and Results : We evaluated vascular inflammation in wild-type (WT) and MRP-14-deficient (MRP-14 −/− ) mice that lack MRP-8/14 complexes with experimental arterial injury, vasculitis, or atherosclerosis. After femoral artery wire injury, MRP-14 −/− mice had a 33% reduction in leukocyte accumulation ( P =.0004) and a 72% reduction in cellular proliferation ( P =0.001) in the arterial wall followed by a 45% reduction in neointima formation ( P =0.004) compared to WT mice. In a cytokine-induced local Schwartzman-like reaction that produces thrombohemorrhagic vasculitis, MRP-14 −/− mice had a 59% reduction in lesion severity ( P <0.0001), an 82% smaller hemorrhagic area ( P =0.015), and a 45% decline in neutrophil accumulation ( P =0.013). Finally, in response to high-fat feeding, mice doubly deficient in ApoE and MRP-8/14 complexes had attenuation in atherosclerotic lesion area by 34% ( P =0.023) and a 60% decrease in macrophage accumulation in plaques ( P =0.021) compared to mice deficient in ApoE alone. Conclusions: This study demonstrates that MRP-8/14 broadly regulates vascular inflammation and contributes to the biological response to vascular injury. Targeting MRP-8/14 may provide a novel therapeutic approach to modulate diverse forms of vascular injury, including restenosis, vasculitis, and atherosclerosis.

Alterations in Heparan Sulfate in the Vessel in Response to Vascular Injury in the Mouse

Heparan sulfate (HS) is ubiquitous throughout the human body. The backbone of HS is composed of many types of sugars. HS serves as a docking site for a vast array of protein ligands. Recent evidence suggests a unique diversity in HS structure that alters protein binding and protein function. This diversity in HS structure has been overlooked till now. The goal of this study was to determine whether femoral artery wire injury modified HS structure. Femoral artery wire injury was performed in 16-week-old male C57BL6 mice. Transcript levels of a panel of enzymes that regulate HS fine structure, including N-deacetylase-N-sulfotransferases (Ndst) 1 and 2, exostoses (Ext) 1 and 2, C5 epimerase, and 2-O and 6-O sulfotransferases, were quantified with real-time quantitative polymerase chain reaction at 7 and 14 days post injury. All enzymes showed significant alterations in messenger RNA expression in response to injury. Ndst1, the most prevalent isoform, exhibited a 20-fold increase in response to injury. Injury induced significant alterations in fine structure specially increases in N-sulfated disaccharides at 14 days post injury. Vascular injury invokes transcriptional regulation of the enzymes that regulate HS structure, as well as changes in the pattern of HS chains in the vessel wall 14 days post injury. These findings may be important as the foundation of altered growth factor and chemokine binding in the process of vascular remodeling.

Abstract 1306: Late-outgrowth Endothelial Cells Attenuate Intimal Hyperplasia Contributed By Mesenchymal Stem Cells After Vascular Injury

Objectives: Mesenchymal stem cells (MSCs) from the bone marrow (BM) are pluripotent and have the capacity to differentiate into cardiomyocytes, endothelial cells (ECs), and smooth muscle cells (SMCs). Currently, MSCs are one of a number of cell types undergoing extensive investigation for cardiac regeneration therapy. However, it has not yet been determined whether this cell therapy also substantially contributes to vascular remodeling of diseased vessels, such as in intimal hyperplasia. Methods and Results: Human MSCs and a variety of progenitor and vascular cells were used for in vitro and in vivo adhesion experiments. To test the contribution of MSCs to intimal hyperplasia, MSCs from eGFP mice were injected via the tail vein of wild-type littermates after femoral artery wire injury. A model of direct BM transplantation of eGFP MSCs into the tibias of irradiated wild-type littermates was also conducted. Wire-induced vascular injury mobilized MSCs into the circulation. Compared to human aortic SMCs, MSCs exhibited a 2.8-fold increase in the adhesion capacity in vitro ( p < 0.001), and a 6.3-fold increase in vivo ( p < 0.001). In all animal models, immunostaining showed that a significant amount of eGFP MSCs contributed to intimal hyperplasia after vascular injury. Furthermore, MSCs were able to differentiate into cells of endothelial or smooth muscle lineage on the injured vessel wall. Co-culture experiments demonstrated that late-outgrowth ECs guided MSCs to differentiate towards an endothelial lineage through a paracrine effects rather than direct cell-cell interactions. In vivo , cell therapy with late-outgrowth ECs significantly attenuated the thickness of the neointima contributed by MSCs (intima/media ratio, from 3.2 ± 0.4 to 0.4 ± 0.1, p < 0.001). Conclusions: This study raises concerns about the detrimental effects of stem cell therapy on injured vessel remodeling. Tissue regeneration therapy with MSCs or cell populations containing MSCs requires a strategy to attenuate the high potential of MSCs to develop intimal hyperplasia on diseased vessels.

Abstract 240: Inhibition of Glycogen Synthase Kinase 3 Beta Improves EPC Yield, Function and Ameliorates Arterial Repair Post-injury and Stenting

Endothelial progenitor cells (EPCs) are circulating undifferentiated pluripotent cells capable of reconstituting endothelium in vivo and diminishing lesion formation following arterial injury. We tested the hypothesis that treatment with a specific soluble GSK 3β-inhibitor (GSK3βi) would improve the in vitro yield and function of EPCs from patients with coronary artery disease (CAD) and augment their in vivo potential to improve arterial repair after injury and stent implantation. In vitro treatment with GSK3βi at 1× (IC50) and 2× (IC50) increased the number of cells that dual labelled for acLDL and UEA-1 lectin on day 7 (13.4±3.2 vs. 39.9±5.3 vs. 43.8±10.1; p < 0.05). Furthermore, GSK3βi significantly augmented CAD-EPC survival to levels equal to those of healthy controls, increased VEGF secretion (7.1±1.6 vs 30.0±8.9, p<0.05) and resulted in a 4× increase in adhesion (p<0.05). Using Q-PCR, mRNA copy numbers for VLA-1,2,3,4 and 5 were assayed; however, only VLA-4 levels increased (4×, p<0.01). Use of a VLA-4 specific blocking antibody confirmed that the improved EPC adhesion was specifically mediated by VLA-4. Finally, the effects of GSK 3β inhibition were tested in two in vivo models of arterial injury. CD-1 athymic nude mice underwent femoral artery wire injury and injection of CAD-EPCs that were either GSK3βi treated, untreated, or injection with vehicle alone. GSK3βi treated EPCs improved the ability of xenotransplanted cells to inhibit lesion formation when compared to untreated and vehicle arteries respectively (intima/media ratios: 0.3±0.1 vs. 5.3±1.2 vs 11.2±2.7 μm, p<0.01). GSK3βi coated stents were inserted into rabbit carotid arteries. Fourteen days after stent deployment, GSK3βi stents resulted in a 44% increase in re-endothelialization (assessed by scanning electron microscopy and compared to vehicle coated stents; p<0.01) and a 16% trend towards a reduction in neointima formation (p<0.09). In summary, our data demonstrates that GSK3βi improves EPC function in vitro and ameliorates arterial repair following injury and stent insertion in vivo .

C-Reactive Protein and Reendothelialization

See related article, pages 1452–1459 Disruption of the endothelium and its subsequent dysfunction appears to set the stage for atherogenesis.1 The maintenance of vascular homeostasis depends in part on a balance between endothelium-derived relaxing and contracting factors. Alterations in this balance lead to inflammation and the formation of fatty streaks and fibrous plaques. The diminished production or availability of nitric oxide (NO) appears paramount to setting the stage for inflammation and vascular injury. In addition to its vasodilatory effect on the vasculature, endothelium-derived NO promotes endothelial cell growth, survival and migration,2 stimulates angiogenesis and neovascularization in part by endothelial progenitor cell (EPC) recruitment,3 inhibits leukocyte adhesion to the endothelium,4 maintains vascular smooth muscle in a nonproliferative state,5 and limits platelet aggregation and thrombosis.6 Maintenance of an intact and functional endothelium protects against vascular disease while its disruption is detrimental. The study by Schwartz et al,7 in this issue of Circulation Research , adds to our understanding of how C-reactive protein (CRP) works to promote vascular pathology by inhibiting NO synthesis. CRP, long regarded as an acute phase protein and an active participant in the innate immune system, has more recently been linked to the development of cardiovascular disease.8 On the basis of several prospective epidemiologic studies, circulating high sensitivity CRP has emerged as an independent predictor of cardiovascular disease risk in various subgroups of patients, including those without overt cardiovascular disease, patients with stable angina or acute coronary syndromes, and in those with the metabolic syndrome.9–12 In primary prevention, CRP confers additional prognostic value at all levels of Framingham risk score and blood pressure.13,14 However, whether or not CRP plays a direct biological role in the initiation and progression of atherosclerosis is controversial.15,16 …

Role of cysteinyl leukotrienes in the proliferation and the migration of murine vascular smooth muscle cells in vivo and in vitro

Objective Cysteinyl leukotrienes (Cys-LTs) are proinflammatory lipid mediators generated from arachidonic acid through 5-lipoxygenase (5-LO). It was reported that the 5-LO pathway is associated with vascular smooth muscle cell (VSMC) proliferation and migration; however, the relationship between Cys-LTs and VSMC proliferation and migration remains unclear. Methods: We used a mouse (C57/BL6J) model of femoral artery wire injury, and compared neointimal formation between controls and animals treated with the Cys-LT receptor antagonist, Montelukast (3 mg/kg/day). The effects of Cys-LTs with or without Montelukast on mouse aortic VSMC proliferation and migration were also investigated. Results After wire injury, neointimal hyperplasia was observed, and immunohistochemical analysis demonstrated expression of the Cys-LT receptors (Cys-LT1 and Cys-LT2) and α-smooth muscle actin in the injured arterial walls. RT-PCR analysis revealed that transcription was not altered during the observation period (before, 1, 2 and 4 weeks after injury). Administration of Montelukast significantly inhibited neointimal formation 4 weeks after injury (intima/media ratio; control group 1.94±0.56 versus Montelukast-treated group 0.94±0.26, n =11, P <0.001). In an in vitro study, LTD4, but not LTC4 and LTE4 significantly stimulated VSMC proliferation (1000 nM), and this effect was inhibited by Montelukast (10 μM). LTC4, LTD4 and LTE4 significantly stimulated VSMC migration (1000 nM), and this effect was inhibited by Montelukast (10 μM). Conclusions Our data suggest that Cys-LTs are involved in VSMC proliferation and migration, and a Cys-LT receptor antagonist may have beneficial effects on vascular remodeling after mechanical injury.

Transgenic expression of human C-reactive protein suppresses endothelial nitric oxide synthase expression and bioactivity after vascular injury

C-reactive protein (CRP) is a risk marker and a potential modulator of vascular disease. Whether CRP modulates nitric oxide (NO) synthase (NOS) activity and NO metabolism remains unclear. We studied the effect of CRP on NO metabolism in transgenic mice that express human CRP (CRPtg). CRPtg and wild-type mice were subjected to controlled femoral artery wire injury. CRP serum levels at baseline and 6 and 24 h after injury were 12.4 +/- 9, 18.6 +/- 6.9, and 58.4 +/- 13 mg/l, respectively, in CRPtg mice but were undetectable at all time points in wild-type mice. Endothelial NOS protein and mRNA expression were significantly suppressed in the injured arteries of CRPtg mice (n = 5, P < 0.05). A similar reduction in eNOS expression was observed in the distant lung and heart. NO release after injury was significantly lower in CRPtg mice, as measured by nitrate and nitrite breakdown products, with a concomitant suppression of cGMP NO signaling after injury. Endothelial NOS and NO expression after vascular injury are locally and systemically suppressed in mice that express human CRP. These in vivo observations support the hypothesis that CRP modulates NO metabolism and may have implications regarding the mechanisms by which CRP modulates vascular disease.

Femoral artery neointimal hyperplasia is reduced after wire injury in Ref-1+/− mice

Redox factor-1 (Ref-1) is a multifunctional protein that regulates redox, DNA repair, and the response to cell stress. We previously demonstrated that Ref-1(+/-) mice exhibit a significantly reduced Ref-1 mRNA and protein levels within the vasculature, which are associated with increased oxidative stress. The goal of this study was to test the hypothesis that partial loss of Ref-1 altered the cellular response to vascular injury. Fourteen days after femoral artery wire injury, we found that vessel intima-to-media ratio was significantly reduced in Ref-1(+/-) mice compared with that in wild-type mice (P < 0.01). Bromodeoxyuridine labeling and transferase-mediated dUTP nick-end labeling staining at 14 days did not differ in the Ref-1(+/-) mice. In vitro studies found no significant changes in either serum-induced proliferation or baseline apoptosis in Ref-1(+/-) vascular smooth muscle cells. Exposure to Fas ligand; however, did result in increased susceptibility of Ref-1(+/-) vascular smooth muscle cells to apoptosis (P < 0.001). Ref-1(+/-) mice exhibited an increase in circulating baseline levels of IL-10, IL-1alpha, and VEGF compared with those in wild-type mice but a marked impairment in these pathways in response to injury. In sum, loss of a single allele of Ref-1 is sufficient to reduce intimal lesion formation and to alter circulating cytokine and growth factor expression.

Double Jeopardy

See related article, pages 149–156 In this issue of Circulation Research , Woollard et al identify a critical role of pathologically elevated levels of soluble P-selectin (sP-selectin) found in the plasma of patients with peripheral arterial occlusive disease (PAOD) that promotes the activation of neutrophils and induces their adhesion to fibrinogen and platelet monolayers.1 P-selectin is an inflammatory adhesion molecule expressed on activated platelets and endothelial cells.2 During the last two decades, the role of inflammatory cells and adhesion molecules in the development and progression of vascular diseases has become apparent, and it is now recognized that many of the cellular and molecular events that underlie atherosclerotic vascular disease are inflammatory in nature.3,4 One manifestation of atherosclerosis is PAOD, which is characterized by intermittent claudication and critical limb ischemia.5 The first case of intermittent claudication caused by arterial occlusive disease was described as early as 1831 by Jean Bouley, and a few years later Heinrich Erb proposed walking as a therapy for intermittent claudication6; however, the precise mechanism of development of PAOD as well as the optimal treatments of this disease still remain to be determined. Numerous studies have identified soluble inflammatory markers including acute phase proteins and adhesion molecules as risk factors for cardiovascular disease, but it is unclear whether they play causative roles as active participants in the initiation and maintenance of the inflammation (mediators) or whether they merely indicate the existence of the disease (markers). Soluble P-selectin is elevated in patients with vascular disorders such as hypertension,7 hypercholesterolaemia, …

Leukocyte Engagement of Platelet Glycoprotein Ibα via the Integrin Mac-1 Is Critical for the Biological Response to Vascular Injury

Leukocyte-platelet interactions are critical in the initiation and progression of atherosclerosis as well as restenosis. Although the leukocyte integrin Mac-1 (alphaMbeta2, CD11b/CD18) has been implicated in the firm adhesion and transmigration of leukocytes at sites of platelet deposition, the precise alphaMbeta2 counterligand responsible for mediating adhesion-strengthening interactions between neutrophils and platelets in vivo has not previously been identified. Our previous studies have established the P201-K217 sequence in the alphaMI domain as the binding site for platelet glycoprotein (GP) Ibalpha. Here we report that antibody targeting of alphaM(P201-K217) reduced alphaMbeta2-dependent adhesion to GP Ibalpha but not other alphaMbeta2 ligands, including fibrinogen, intercellular adhesion molecule-1, and junctional adhesion molecule-3. Anti-alphaM(P201-K217) inhibited the firm adhesion of both human and murine leukocytes to adherent platelets under laminar flow conditions. In a mouse femoral artery wire injury model, antibody targeting of alphaM(P201-K217) reduced leukocyte accumulation after injury that was accompanied by inhibition of cellular proliferation and neointimal thickening. This study demonstrates that GP Ibalpha is a physiologically relevant ligand for alphaMbeta2 and that integrin engagement of GP Ibalpha is critical to leukocyte function and the biological response to vascular injury. These observations establish a molecular target for selectively disrupting leukocyte-platelet complexes that promote inflammation in thrombosis and restenosis.

Effects of Simvastatin on Plasma Lipoproteins and Response to Arterial Injury in Wild-Type and Apolipoprotein-E-Deficient Mice

Objective: To test the non-lipid-lowering effects of simvastatin on the response to injury in normolipidemic and hyperlipidemic mice. Methods and Results: Wild-type (WT) mice (n = 40) and hyperlipidemic apolipoprotein-E-deficient (apoE^–/–) mice (n = 40) received normal chow or chow containing simvastatin 100 mg/kg/day prior to bilateral femoral artery wire injury. Intimal hyperplasia and plasma cholesterol concentration were quantified after 4 weeks. Plasma cholesterol in WT mice treated or untreated with simvastatin was similar (100.9 ± 6.6 vs. 94.3 ± 17.5 mg/dl). Simvastatin did not affect intimal hyperplasia. In apoE^–/– mice, intimal hyperplasia was increased 2.3-fold relative to WT mice (17,090 ± 4,998 vs. 39,490 ± 16,190; p < 0.001). In apoE^–/–mice, simvastatin caused a paradoxical increase in plasma cholesterol (1,094 ± 60.3 vs. 658 ± 66.8 mg/dl; p < 0.001), confirmed by FPLC. This was associated with a further increase in intimal area (39,490 ± 16,190 vs. 55,420 ± 22,590 mm²; p < 0.01). Conclusions: (1) Simvastatin had no effect on plasma cholesterol or the response to arterial injury in normolipidemic WT mice; (2) hyperlipidemia was associated with markedly increased intimal hyperplasia, and (3) simvastatin treatment of apoE^–/– mice caused paradoxical hyperlipidemia and increased intimal hyperplasia.