Intimal Area Research Articles

A Role of RIP3-Mediated Macrophage Necrosis in Atherosclerosis Development

Necrotic death of macrophages has long been known to be present in atherosclerotic lesions but has not been studied. We examined the role of receptor interacting protein (RIP) 3, a mediator of necrotic cell death, in atherosclerosis and found that RIP3(-/-);Ldlr(-/-) mice were no different from RIP3(+/+);Ldlr(-/-) mice in early atherosclerosis but had significant reduction in advanced atherosclerotic lesions. Similar results were observed in Apoe(-/-) background mice. Bone marrow transplantation revealed that loss of RIP3 expression from bone-marrow-derived cells is responsible for the reduced disease progression. While no difference was found in apoptosis between RIP3(-/-);Ldlr(-/-) and RIP3(+/+);Ldlr(-/-) mice, electron microscopy revealed a significant reduction of macrophage primary necrosis in the advanced lesions of RIP3(-/-) mice. In vitro cellular studies showed that RIP3 deletion had no effect on oxidized low-density lipoprotein (LDL)-induced macrophage apoptosis, but prevented macrophage primary necrosis occurring in response to oxidized LDL under caspase inhibition or RIP3 overexpression conditions. RIP3-dependent necrosis is not postapoptotic, and the increased primary necrosis in advanced atherosclerotic lesions most likely resulted from the increase of RIP3 expression. Our data demonstrate that primary necrosis of macrophages is proatherogenic during advanced atherosclerosis development.

Inhibition of intimal hyperplasia by local perivascular application of rapamycin and imatinib mesilate after carotid balloon injury

PurposeInhibition of the intimal hyperplasia after vascular surgery is an important issue. The purpose of this study is to define whether perivascular application of rapamycin, imatinib mesylate or cysteamine can reduce intimal hyperplasia in a carotid balloon injury model.MethodsEach drug was mixed with 40% pluronic gel solution and was topically applied over the injured carotid artery evenly. Two or four weeks after injury, the arteries were harvested and morphometric analysis was done.ResultsThe medial areas were not significantly different in each group and a thinning of the media as a toxic drug effect was not observed in any treatment group. The intimal area and intima-to-media (I/M) ratio were significantly reduced in rapamycin-treated group and imatinib-treated group (P < 0.05). But cysteamine-treated group showed a trend of decrease in I/M ratio in 2 weeks, but no difference in 4 weeks.ConclusionPerivascular delivery of imatinib or rapamycin with pluronic gel attenuated the development of intimal hyperplasia. But cysteamine did not. Further studies are needed to refine the optimal drug dosages in large animal models.

Magnolol attenuates neointima formation by inducing cell cycle arrest via inhibition of ERK1/2 and NF-κB activation in vascular smooth muscle cells

BackgroundEndovascular injury induces switching of contractile phenotype of vascular smooth muscle cells (VSMCs) to synthetic phenotype, thereby causing proliferation of VSMCs leading to intimal thickening. The purpose of this study was to assess the effect of magnolol on the proliferation of VSMCs in vitro and neointima formation in vivo, as well as the related cell signaling mechanisms. MethodsTumor necrosis factor alpha (TNF-α) induced proliferation of VSMCs was assessed using colorimetric assay. Cell cycle progression and mRNA expression of cell cycle associated molecules were determined by flow cytometry and reverse transcription polymerase chain reaction (RT-PCR) respectively. The signaling molecules such as ERK1/2, JNK, P38 and NF-κB were determined by Western blot analysis. In addition, rat carotid artery balloon injury model was performed to assess the effect of magnolol on neointima formation in vivo. ResultsOral administration of magnolol significantly inhibited intimal area and intimal/medial ratio (I/M). Our in vitro assays revealed magnolol dose dependently induced cell cycle arrest at G0/G1. Also, magnolol inhibited mRNA and protein expression of cyclin D1, cyclin E, CDK4 and CDK2 in vitro and in vivo. The cell cycle arrest was associated with inhibition of ERK1/2 phosphorylation and NF-κB translocation. ConclusionMagnolol suppressed proliferation of VSMCs in vitro and attenuated neointima formation in vivo by inducing cell cycle arrest at G0/G1 through modulation of cyclin D1, cyclin E, CDK4 and CDK2 expression. General significanceThus, the results suggest that magnolol could be a potential therapeutic candidate for the prevention of restenosis and atherosclerosis.

On the Importance of Modeling Stent Procedure for Predicting Arterial Mechanics

The stent-artery interactions have been increasingly studied using the finite element method for better understanding of the biomechanical environment changes on the artery and its implications. However, the deployment of balloon-expandable stents was generally simplified without considering the balloon-stent interactions, the initial crimping process of the stent, its overexpansion routinely used in the clinical practice, or its recoil process. In this work, the stenting procedure was mimicked by incorporating all the above-mentioned simplifications. The impact of various simplifications on the stent-induced arterial stresses was systematically investigated. The plastic strain history of stent and its resulted geometrical variations, as well as arterial mechanics were quantified and compared. Results showed the model without considering the stent crimping process underestimating the minimum stent diameter by 17.2%, and overestimating the maximum radial recoil by 144%. It was also suggested that overexpansion resulted in a larger stent diameter, but a greater radial recoil ratio and larger intimal area with high stress were also obtained along with the increase in degree of overexpansion.

Abstract 19325: Genetic Ablation of the P2y2 Nucleotide Receptor Reduces Atherosclerosis in Mice

Objective: We have shown that nucleotide binding to P2Y2 receptor induces endothelial activation via enhanced VCAM-1 expression leading to intimal recruitment of monocyte/macrophage. Here, we sought to determine whether genetic ablation of P2Y2 receptor affects the development of atherosclerosis. Methods and Results: Western blot and immumofluorescence analysis revealed that P2Y2 receptor deficiency in ApoE mice is accompanied by a sharp reduction in basal VCAM-1 expression levels. To analyze the consequence of P2Y2 receptor deficiency in endothelial function, we examined transmigration of monocytes isolated from the peripheral blood of wt or P2Y2R −/− mice across wt or P2Y2R −/− endothelial monolayers in response to monocyte chemoattractant protein-1. Absence of P2Y 2 R in endothelial cells significantly impaired monocyte transmigration. Remarkably, loss of P2Y2 receptor in monocytes did not significantly impair transmigration in the presence (transendothelial) or absence (chemotaxis) of P2Y2R +/+ endothelial monolayers, suggesting that endothelial P2Y2R is relatively more important than monocytic P2Y 2 R in regulating monocyte motility. The absence of P2Y 2 R did not significantly change the plasma cholesterol or triglyceride levels; however, lipid deposition in the lesion, as demonstrated by Oil Red O–positive region, was decreased by 47% in the aortic preparation from ApoE−/−/P2Y2R+/+ mice. Notably, P2Y2R deficiency in ApoE−/− resulted in a 52% reduction in the area of aortic sinus lesion as compared to ApoE −/− mice. Consistent with reduced lesion size, decreased macrophage content was observed in the sinus aortic lesions of ApoE−/−/P2Y 2 R −/− mice. Staining for SMC showed that most of the SMCs were in the intimal area close to the lumen. The staining showed a 36% decrease in ApoE−/−/P2Y 2 R −/− when compared with ApoE −/− /P2Y2R +/+ mice. Staining with Sirius red showed that the interstitial collagen content of the lesions of ApoE −/− /P2Y2R +/+ mice was 2-fold higher than in ApoE−/−/P2Y2R −/−mice. Conclusion: These observations suggest that genetic ablation of P2Y 2 R significantly decreases both macrophage accumulation and interstitial fibrosis but also reduces smooth muscle cell content of sinus aortic lesions.

Nitric oxide delivery via a permeable balloon catheter inhibits neointimal growth after arterial injury

BackgroundNeointimal hyperplasia limits the longevity of vascular interventions. Nitric oxide (NO) is well known to inhibit neointimal hyperplasia. However, delivery of NO to the vasculature is challenging. Our study aims to evaluate the efficacy of delivering NO to the site of injury using a permeable balloon catheter. Our hypothesis is that ultra-short duration NO delivery using a permeable balloon catheter will inhibit neointimal hyperplasia. Materials and methodsTen-week-old male Sprague-Dawley rats underwent carotid artery balloon injury. Groups included: (1) control, (2) injury, (3) injury + periadventitial NO, and (4) injury + endoluminal NO via permeable balloon catheter. The catheter was inflated to 5 atm pressure for 5 min. Arteries were harvested 2 wk following injury. Morphometric assessment for neointimal hyperplasia and immunohistochemical staining for inflammatory markers were performed. ResultsInjury increased neointimal hyperplasia compared with control (intima/media area [I/M] ratio 1.07 versus 0.11, respectively, P < 0.001). Periadventitial delivery of NO reduced the I/M area ratio compared with injury alone (55% decrease, P < 0.001). Endoluminal delivery of NO also reduced the I/M area ratio compared with injury alone (65% decrease; P < 0.001). Both endoluminal and periadventitial NO affected the I/M ratio by reducing the intimal area (64% and 46%, respectively, P < 0.001) whereas neither affected the medial area. Periadventitial NO delivery increased lumen area (P < 0.05), whereas endoluminal NO delivery increased circumference (P < 0.05). Periadventitial NO delivery inhibited macrophage intimal infiltration compared with injury alone (P < 0.05). ConclusionsThese data demonstrate that short-duration endoluminal NO delivery via permeable balloon catheters inhibits neointimal hyperplasia following arterial interventions. Endoluminal delivery of NO could become a focus for future clinical interventions.

The contribution of HIV infection to intracranial arterial remodeling: A pilot study

Pathological arterial wall changes have been cited as potential mechanisms of cerebrovascular disease in the HIV population. We hypothesize that dilatation would be present in arterial walls of patients with HIV compared to controls. Fifty-one intracranial arteries, obtained from autopsies of five individuals with HIV infection and 13 without, were fixed, embedded, stained, and digitally photographed. Cross-sectional areas of intima, media, adventitia and lumen were measured by preset color thresholding. A measure of arterial remodeling was obtained by calculating the ratio between the lumen diameter and the thickness of the arterial wall. Higher numbers indicate arterial dilatation, while lower numbers indicate arterial narrowing. HIV-infected brain donors were more frequently black (80% vs. 15%, P = 0.02) compared with uninfected donors. Inter and intra-reader agreement measures were excellent. The continuous measure of vascular remodeling was significantly higher in the arteries from HIV donors (β = 2.8, P = 0.02). Adjustments for demographics and clinical covariates strengthen this association (β = 9.3, P = 0.01). We found an association of HIV infection with outward brain arterial remodeling. This association might be mediated by a thinner media layer. The reproduction of these results and the implications of this proposed pathophysiology merits further study.

Experimental research Effect of 1α-25-dihydroxyvitamin D 3 on intimal hyperplasia developing in vascular anastomoses: a rabbit model

IntroductionA common problem encountered in routine daily practice of cardiovascular surgery is migration of smooth muscle cells leading to intimal hyperplasia developing at vascular anastomosis sites which then causes luminal narrowing. The aim of this study was to investigate the antiproliferative effect of 1,25 (OH)2D3 on intimal hyperplasia.Material and methodsTwenty-one male white New Zealand rabbits weighing 2-3 kg were selected. There were 3 groups of animals each consisting of 7 rabbits. Group 1 was the control group. Group 2 was the sham group and group 3 consisted of rabbits receiving 1,25 (OH)2D3. The right carotid arteries of the subjects in groups 2 and 3 were transected and re-anastomosed. A daily dose of 25 ng 1,25 (OH)2D3 per 100 g body weight was administered for 14 days to rabbits in group 3. Rabbits in group 2 were not subject to any pharmaceutical agent. All the subjects were sacrificed at the end of the 28th postoperative day. Their right carotid arteries were resected and then investigated histopathologically.ResultsIntimal thickness and intimal area were measured as significantly lower in group 1 when compared with the other groups (p = 0.004). In group 3, the ratios of thickness of tunica intima/thickness of tunica media and area of tunica intima/area of tunica media were significantly lower than those of group 2 (p = 0.015, p = 0.003).Conclusions1,25 (OH)2D3, the active metabolite of vitamin D, reduces the intimal hyperplasia developing after vascular anastomoses.

Combination therapy of atorvastatin and probucol on ischemic stroke in clinic

A significant drop of blood lipids (P<0.01), IMT(P<0.01), area of Carotid intima of atherosclerotic plaque(P<0.01), PAPP-A(P<0.01) and hs-CRP( P<0.01) were observed in atorvastatin+ probucol group. All parameters were improved significantly comparing with atorvastatin alone. Neurological deficit scores of these two groups had significantly different after treatment (P<0.01). Combination therapy had better efficacy. The correlation analysis showed that seriousness of ischemic stroke on admission day and 1 month of treatment was associated with the hsCRP levels significantly. Conclusion Short-term use of atorvastatin combining with probucol could have a significant effect on ischemic stroke in clinic.

Effects of arterial strain and stress in the prediction of restenosis risk: Computer modeling of stent trials

In-stenting restenosis is one of the major complications after stenting. Clinical trials of various stent designs have reported different restenosis rates. However, quantitative correlation between stent features and restenosis statistics is scant. In this work, it is hypothesized that stress concentrations on arterial wall caused artery injury, which initiates restenosis. The goal is to assess the correlation between stent-induced arterial stress and strain and the documented restenosis rates Six commercially available stents, including balloon-expandable stents and self-expanding stents, were virtually implanted into the arteries through finite element method. The resulted peak Von Mises stress, principal stress, principal logarithm strain, as well as percentage of intimal area with abnormal higher stress were monitored. Positive correlation between arterial stress and strain after stent implantations and the documented restenosis rates from the corresponding clinical trials was found regardless of stent types. No statistical significant difference was observed for various stress or strain parameters serving as indicators of artery injury. In-stent restenosis are less likely to occur as arterial mechanics are least altered by stent implantations. Optimization of stent designs to minimize the stent-induced arterial stresses and strains can reduce the arterial injury, and thus reduce the occurrence of restenosis. This work improved our understanding of the stent-lesion interactions that regulate arterial mechanics and demonstrated that arterial stress and strain could predict the risk of in-stent restenosis.

Gastrodin inhibits cell proliferation in vascular smooth muscle cells and attenuates neointima formation in vivo

Vascular smooth muscle cell (VSMC) proliferation plays a critical role in the development of vascular diseases. In the present study, we tested the efficacy and the mechanisms of action of gastrodin, a bioactive component of the Chinese herb Gastrodia elata Bl, in relation to platelet-derived growth factor-BB (PDGF-BB)-dependent cell proliferation and neointima formation after acute vascular injury. Cell experiments were performed with VSMCs isolated from rat aortas. WST and BrdU incorporation assays were used to evaluate VSMC proliferation. Eight-week-old C57BL/6 mice were used for the animal experiments. Gastrodin (150 mg/kg/day) was administered in the animal chow for 14 days, and the mice were subjected to wire injury of the left carotid artery. Our data demonstrated that gastrodin attenuated the VSMC proliferation induced by PDGF-BB, as assessed by WST assay and BrdU incorporation. Gastrodin influenced the S-phase entry of VSMCs and stabilised p27Kip1 expression. In addition, pre-incubation with sinomenine prior to PDGF-BB stimulation led to increased smooth muscle-specific gene expression, thereby inhibiting VSMC dedifferentiation. Gastrodin treatment also reduced the intimal area and the number of PCNA-positive cells. Furthermore, PDGF-BB-induced phosphorylation of ERK1/2, p38 MAPK, Akt and GSK3β was suppressed by gastrodin. Our results suggest that gastrodin can inhibit VSMC proliferation and attenuate neointimal hyperplasia in response to vascular injury. Furthermore, the ERK1/2, p38 MAPK and Akt/GSK3β signalling pathways were found to be involved in the effects of gastrodin.

Mathematical model of intimal thickening in atherosclerosis: Vessel stenosis as a free boundary problem

Atherosclerosis is an inflammatory disease of the artery characterized by an expansion of the intimal region. Intimal thickening is usually attributed to the migration of smooth muscle cells (SMCs) from the surrounding media and proliferation of SMCs already present in the intima. Intimal expansion can give rise to dangerous events such as stenosis (leading to stroke) or plaque rupture (leading to myocardial infarction).In this paper we propose and study a mathematical model of intimal thickening, posed as a free boundary problem. Intimal thickening is driven by damage to the endothelium, resulting in the release of cytokines and migration of SMCs. By coupling a boundary value problem for cytokine concentration to an evolution law for the intimal area, we reduce the problem to a single nonlinear differential equation for the luminal radius. We analyze the steady states, perform a bifurcation analysis and compare model solutions to data from rabbits whose iliac arteries are subject to a balloon pullback injury. In order to obtain a favorable fit, we find that migrating SMCs must enter the intima very slowly compared to cells in dermal wounds. This cell behavior is indicative of a weak inflammatory response which is consistent with atherosclerosis being a chronic inflammatory disease.

Experimental research on the prevention of autologous vein graft restenosis by fibrin glue combined with tissue inhibitor of metalloproteinase-1

Objective To investigate the mechanism of attenuation of restenosis by applying fibrin glue combined with tissue inhibitor of metalloproteinase-1 (TIMP-1) locally on vein graft.Methods Twenty-four New Zealand white rabbits were randomly divided into 3 groups with 8 rabbits in each group:non-support group (NS group),fibrin glue group (FS group) and fibrin glue + TIMP-1 group (TS/FS group).All animals underwent unilateral jugutar vein into common carotid artery interposition grafting.After operation,vein grafts were harvested at 28th day for histopathologic measurement of intimal thickness,media thickness and intimal areas,media areas,reverse transcription-polymerase chain reaction (RTPCR) and Western blotting analyses of TIMP-1 gene expression.Results At 28th day after the operation,the mean intimal thickness and intimal areas of the TS/FS group were (37.98 ±4.19) μm and (0.557 ±0.049) mm2 respectively,which were reduced obviously as compared with NS group and FS group (P ＜0.05).The mean media thickness and media areas in the TS/FS group were (28.45 ± 3.01 ) μm and (0.458 ±0.053) mm2 respectively,which were decreased statistically as compared with NS group and FS group (P ＜ 0.05).RT-PCR and Western blotting analysis revealed that the gene expression of TIMP-1 was increased in TS/FS group as eompared with NS group and FS group (P ＜ 0.05).Conclusion The expression of TIMP-1 in vein grafts can be up-regulated by adventitial delivery of TIMP-1.The fibrin glue combined with TIMP-1 has synergistic effect on reducing neointimal and media thickness of vein grafts. Key words: Vein graft; Restenosis; Fibrin glue; Tissue inhibitor of metalloproteinase-1

Abstract 343: Inactivation of the P2Y2 Receptor Gene Reduces Atherosclerosis

Rationale: Nucleotides acting via P2Y 2 nucleotide receptors (P2Y 2 R) regulate both migration of vascular smooth muscle cells and endothelial recruitment of monocyte/macrophage in vivo. Objective: We aimed to determine whether inactivation of the P2Y 2 R gene protects against neointima hyperplasia and atherosclerosis. Method and results: We performed femoral artery cuff injury in wild-type and P2Y 2 R -/- mice and examined neointima formation 14 days after injury, the time corresponding to peak SMC accumulation in this model. Wild-type mice exhibited a 190% increase in cellular proliferation ( P &lt;0.001) in the arterial wall as assessed by BrdU incorporation, and a 150% increase in neointima formation ( P =0.010) compared to wild-type mice. There was no significant difference in the medial area between wild type and P2Y 2 R -/- mice. To assess the contribution of P2Y 2 R to atherosclerosis, we first generated P2Y 2 R -/- /ApoE -/- mice by mating ApoE -/- mice with P2Y 2 R -/- mice. We then examined the development of atherosclerotic lesions 30 weeks after mice were fed with standard chow diet, the time corresponding to widespread atherosclerotic lesions in the ApoE -/- mouse model. P2Y 2 R -/- /ApoE -/- and ApoE -/- exhibited no differences in blood pressure, number of circulating leukocytes, differential counts, or total blood cholesterol. The surface covered by atherosclerotic lesions in the entire aorta was significantly reduced in P2Y 2 R -/- /ApoE -/- mice as compared to ApoE -/- . The total intimal lesion area in the aortic sinus was significantly less in P2Y 2 R -/- /ApoE -/- mice than in ApoE -/- mice. Mac-3 staining revealed a significant reduction in the percentage of total plaque area occupied by macrophages in P2Y 2 R -/- /ApoE -/- mice compared with Apo E -/- mice. Conclusion: These findings suggest that unraveling the molecular mechanisms associated with P2Y 2 R may lead to potential drug targets for the treatment of coronary syndromes and percutaneous coronary interventions.

Omega-3 Fatty Acids Ameliorate Atherosclerosis by Favorably Altering Monocyte Subsets and Limiting Monocyte Recruitment to Aortic Lesions

Fish oil, containing omega-3 fatty acids, attenuates atherosclerosis. We hypothesized that omega-3 fatty acid-enriched oils are atheroprotective through alteration of monocyte subsets and their trafficking into atherosclerotic lesions. Low-density lipoprotein receptor knockout and apolipoprotein E(-/-) mice were fed diets containing 10% (calories) palm oil and 0.2% cholesterol, supplemented with an additional 10% palm oil, echium oil (containing 18:4 n-3), or fish oil. Compared with palm oil-fed low-density lipoprotein receptor knockout mice, echium oil and fish oil significantly reduced plasma cholesterol, splenic Ly6C(hi) monocytosis by ≈50%, atherosclerosis by 40% to 70%, monocyte trafficking into the aortic root by ≈50%, and atherosclerotic lesion macrophage content by 30% to 44%. In contrast, atherosclerosis and monocyte trafficking into the artery wall was not altered by omega-3 fatty acids in apolipoprotein E(-/-) mice; however, Ly6C(hi) splenic monocytes positively correlated with aortic root intimal area across all diet groups. In apolipoprotein E(-/-) mice, fish oil reduced the percentage of blood Ly6C(hi) monocytes, despite an average 2-fold higher plasma cholesterol relative to palm oil. The presence of splenic Ly6C(hi) monocytes parallels the appearance of atherosclerotic disease in both low-density lipoprotein receptor knockout and apolipoprotein E(-/-) mice. Furthermore, omega-3 fatty acids favorably alter monocyte subsets independently from effects on plasma cholesterol and reduce monocyte recruitment into atherosclerotic lesions.

Enhanced drug delivery capabilities from stents coated with absorbable polymer and crystalline drug

Current drug eluting stent (DES) technology is not optimized with regard to the pharmacokinetics of drug delivery. A novel, absorbable-coating sirolimus-eluting stent (AC-SES) was evaluated for its capacity to deliver drug more evenly within the intimal area rather than concentrating drug around the stent struts and for its ability to match coating erosion with drug release. The coating consisted of absorbable poly-lactide-co-glycolic acid (PLGA) and crystalline sirolimus deposited by a dry-powder electrostatic process. The AC-SES demonstrated enhanced drug stability under simulated use conditions and consistent drug delivery balanced with coating erosion in a porcine coronary implant model. The initial drug burst was eliminated and drug release was sustained after implantation. The coating was absorbed within 90days.Following implantation into porcine coronary arteries the AC-SES coating is distributed in the surrounding intimal tissue over the course of several weeks. Computational modeling of drug delivery characteristics demonstrates how distributed coating optimizes the load of drug immediately around each stent strut and extends drug delivery between stent struts. The result was a highly efficient arterial uptake of drug with superior performance to a clinical bare metal stent (BMS). Neointimal thickness (0.17±0.07mm vs. 0.28±0.11mm) and area percent stenosis (22±9% vs. 35±12%) were significantly reduced (p<0.05) by the AC-SES compared to the BMS 30days after stent implantation in an overlap configuration in porcine coronary arteries. Inflammation was significantly reduced in the AC-SES compared to the BMS at both 30 and 90days after implantation.Biocompatible, rapidly absorbable stent coatings enable the matching of drug release with coating erosion and provide for the controlled migration of coating material into tissue to reduce vicissitudes in drug tissue levels, optimizing efficacy and reducing potential toxicity.

Ultrasound-guided percutaneous delivery of tissue-engineered endothelial cells to the adventitia of stented arteries controls the response to vascular injury in a porcine model

High restenosis rates are a limitation of peripheral vascular interventions. Previous studies have shown that surgical implantation of a tissue-engineered endothelium onto the adventitia surface of injured vessels regulates vascular repair. In the present study, we developed a particulate formulation of tissue-engineered endothelium and a method to deliver the formulation perivascular to injured blood vessels using a percutaneous, minimally invasive technique. Stainless steel stents were implanted in 18 balloon-injured femoral arteries of nine domestic swine, followed by ultrasound-guided percutaneous perivascular injection of gelatin particles containing cultured allogeneic porcine aortic endothelial cells (PAE). Controls received injections of empty particles (matrix) or no perivascular injection (sham) after stent deployment. Animals were sacrificed after 90 days. Angiographic analysis revealed a significantly greater lumen diameter in the stented segments of arteries treated with PAE/matrix (4.72 ± 0.12 mm) compared with matrix (4.01 ± 0.20 mm) or sham (4.03 ± 0.16 mm) controls (P < .05). Similarly, histologic analysis revealed that PAE/matrix-treated arteries had the greatest lumen area (20.4 ± 0.7 mm(2); P < .05) compared with controls (16.1 ± 0.9 mm(2) and 17.1 ± 1.0 mm(2) for sham and matrix controls, respectively) and the smallest intimal area (3.3 ± 0.4 mm(2); P < .05) compared with controls (6.2 ± 0.5 mm(2) and 4.4 ± 0.5 mm(2) for sham and matrix controls, respectively). Overall, PAE-treated arteries had a 33% to 50% decrease in percent occlusion (P < .05) compared with controls. Histopathological analysis revealed fewer leukocytes present in the intima in the PAE/matrix group compared with control groups, suggesting that the biological effects were in part due to inhibition of the inflammatory phase of the vascular response to injury. Minimally invasive, perivascular delivery of PAE/matrix to stented arteries was performed safely using ultrasound-guided percutaneous injections and significantly decreased stenosis. Application at the time of or subsequent to peripheral interventions may decrease clinical restenosis rates.

Cilostazol Inhibits Accumulation of Triglyceride in Aorta and Platelet Aggregation in Cholesterol-Fed Rabbits

Cilostazol is clinically used for the treatment of ischemic symptoms in patients with chronic peripheral arterial obstruction and for the secondary prevention of brain infarction. Recently, it has been reported that cilostazol has preventive effects on atherogenesis and decreased serum triglyceride in rodent models. There are, however, few reports on the evaluation of cilostazol using atherosclerotic rabbits, which have similar lipid metabolism to humans, and are used for investigating the lipid content in aorta and platelet aggregation under conditions of hyperlipidemia. Therefore, we evaluated the effect of cilostazol on the atherosclerosis and platelet aggregation in rabbits fed a normal diet or a cholesterol-containing diet supplemented with or without cilostazol. We evaluated the effects of cilostazol on the atherogenesis by measuring serum and aortic lipid content, and the lesion area after a 10-week treatment and the effect on platelet aggregation after 1- and 10-week treatment. From the lipid analyses, cilostazol significantly reduced the total cholesterol, triglyceride and phospholipids in serum, and moreover, the triglyceride content in the atherosclerotic aorta. Cilostazol significantly reduced the intimal atherosclerotic area. Platelet aggregation was enhanced in cholesterol-fed rabbits. Cilostazol significantly inhibited the platelet aggregation in rabbits fed both a normal diet and a high cholesterol diet. Cilostazol showed anti-atherosclerotic and anti-platelet effects in cholesterol-fed rabbits possibly due to the improvement of lipid metabolism and the attenuation of platelet activation. The results suggest that cilostazol is useful for prevention and treatment of atherothrombotic diseases with the lipid abnormalities.

The effects of PPARγ agonist rosiglitazone on neointimal hyperplasia in rabbit carotid anastomosis model

BackgroundNeointimal hyperplasia involving smooth muscle cell (SMC) proliferation, migration and extracellular matrix (ECM) degradation is an important component of atherosclerosis. It develops as a response to vascular injury after balloon angioplasty and vascular graft placement. Matrix metalloproteinases (MMPs) induce SMC proliferation, migration and contribute to intimal hyperplasia by degrading ECM. PPARγ agonists inhibit SMC proliferation, migration and lesion formation. In this study, we aimed to investigate the effects of PPARγ agonist rosiglitazone on neointimal hyperplasia and gelatinase (MMP-2 and MMP-9) expressions in rabbit carotid anastomosis model.MethodsNew Zealand white rabbits (n = 13, 2.7–3.2 kg) were divided into placebo and treatment groups. Right carotid artery (CA) was transected and both ends were anastomosed. Treatment group (n = 6) received rosiglitazone (3 mg/kg/day/p.o.) and placebo group (n = 7) received PBS (phosphate buffered saline, 2.5 ml/kg/day/p.o.) for 4 weeks postoperatively. After the sacrification, right and left CAs were isolated. Morphometric analyses and immunohistochemical examinations for gelatinases were performed.ResultsIntimal area (0.055 ± 0.005 control vs 0.291 ± 0.020 μm2 anastomosed, p < 0,05) and index (0.117 ± 0.002 control vs 0.574 ± 0.013 anastomosed, p < 0,01) significantly increased in anastomosed arteries compared to control arteries from placebo group. However, in rosiglitazone-treated group, intimal area (0.291 ± 0.020 PBS vs 0.143 ± 0.027 rosiglitazone, p < 0,05) and index (0.574 ± 0.013 PBS vs 0.263 ± 0.0078 rosiglitazone, p < 0,01) significantly decreased. Furthermore, gelatinase immunopositivity was found to have significantly increased in anastomosed arteries from placebo group and decreased with rosiglitazone treatment.ConclusionsThese results suggest that rosiglitazone may prevent neointimal hyperplasia, which is the most important factor involved in late graft failure, by inhibiting gelatinase enzyme expression.

The effects of aging on the intimal region of the human saphenous vein: insights from multimodal microscopy and quantitative image analysis

We hypothesized that structural remodeling associated with advancing age occurs in human saphenous veins. To address this hypothesis, we have identified structural remodeling in human saphenous veins by applying histochemistry, fluorescence staining and quantitative image analysis to specifically assess intimal area, intimal cellularity and intimal collagen content and organization. Saphenous veins were collected from patients undergoing coronary artery bypass graft surgery. Area measurements and cellularity were quantified using the image analysis software Stereo Investigator, employing planimetry and counting frames, respectively. Collagen content and organization were quantified in MetaMorph image analysis software based on measurements of color (hue, saturation, and intensity) from polarized light images. Intimal area and cellularity showed no statistically significant increases with age; in contrast, total collagen content showed a significant decrease with advancing age. Furthermore, collagen fiber types also demonstrated a statistically significant alteration with age; increases in age resulted in decreases in larger collagen fibers. No significant changes in small collagen fibers were identified. These results raise the possibility that age-associated structural alterations in total collagen content, specifically collagen fiber size, could be a factor in the etiology of age-associated venous diseases.