Human urinary kininogenase reduces the endothelial injury by inhibiting Pyk2/MCU pathway

The injury of endothelial cells is one of the initiating factors in restenosis after endovascular treatment. Human urinary kallidinogenase (HUK) is a tissue kallikrein which is used for ischemia-reperfusion injury treatment. Studies have shown that HUK may be a potential therapeutic agent to prevent stenosis after vascular injury, however, the precise mechanisms have not been fully established. This study is to investigate whether HUK can protect endothelial cells after balloon injury or H2O2-induced endothelial cell damage through the proline-rich tyrosine kinase 2 (Pyk2)/mitochondrial calcium uniporter (MCU) pathway. Intimal hyperplasia, a decrease of pinocytotic vesicles and cell apoptosis were found in the common carotid artery balloon injury and H2O2-induced endothelial cell damage, Pyk2/MCU was also up-regulated in such pathological process. HUK could prevent these injuries partially via the bradykinin B2 receptor by inhibiting Pyk2/MCU pathway, which prevented the mitochondrial damage, maintained calcium balance, and eventually inhibited cell apoptosis. Furthermore, MCU expression was not markedly increased if Pyk2 was suppressed by shRNA technique in the H2O2 treatment group, and cell viability was significantly better than H2O2-treated only. In short, our results indicate that the Pyk2/MCU pathway is involved in endothelial injury induced by balloon injury or H2O2-induced endothelial cell damage. HUK plays an protective role by inhibiting the Pyk2/MCU pathway in the endothelial injury.

High resolution imaging of the fibrous microstructure in bovine common carotid artery using optical polarization tractography

The biomechanical properties of artery are primarily determined by the fibrous structures in the vessel wall. Many vascular diseases are associated with alternations in the orientation and alignment of the fibrous structure in the arterial wall. Knowledge on the structural features of the artery wall is crucial to our understanding of the biology of vascular diseases and the development of novel therapies. Optical coherence tomography (OCT) and polarization-sensitive OCT have shown great promise in imaging blood vessels due to their high resolution, fast acquisition, good imaging depth, and large field of view. However, the feasibility of using OCT based methods for imaging fiber orientation and distribution in the arterial wall has not been investigated. Here we show that the optical polarization tractography (OPT), a technology developed from Jones matrix OCT, can reveal the fiber orientation and alignment in the bovine common carotid artery. The fiber orientation and alignment data obtained in OPT provided a robust contrast marker to clearly resolve the intima and media boundary of the carotid artery wall. Optical polarization tractography can visualize fiber orientation and alignment in carotid artery.

Common carotid intima media thickness and ankle-brachial pressure index correlate with local but not global atheroma burden: a cross sectional study using whole body magnetic resonance angiography

Background

Common carotid intima media thickness (CIMT) and ankle brachial pressure index (ABPI) are used as surrogate marker of atherosclerosis, and have been shown to correlate with arterial stiffness, however their correlation with global atherosclerotic burden has not been previously assessed. We compare CIMT and ABPI with atheroma burden as measured by whole body magnetic resonance angiography (WB-MRA).

Methods

50 patients with symptomatic peripheral arterial disease were recruited. CIMT was measured using ultrasound while rest and exercise ABPI were performed. WB-MRA was performed in a 1.5T MRI scanner using 4 volume acquisitions with a divided dose of intravenous gadolinium gadoterate meglumine (Dotarem, Guerbet, FR). The WB-MRA data was divided into 31 anatomical arterial segments with each scored according to degree of luminal narrowing: 0 = normal, 1 = <50%, 2 = 50–70%, 3 = 70–99%, 4 = vessel occlusion. The segment scores were summed and from this a standardized atheroma score was calculated.

Results

The atherosclerotic burden was high with a standardised atheroma score of 39.5±11. Common CIMT showed a positive correlation with the whole body atheroma score (β 0.32, p = 0.045), however this was due to its strong correlation with the neck and thoracic segments (β 0.42 p = 0.01) with no correlation with the rest of the body. ABPI correlated with the whole body atheroma score (β −0.39, p = 0.012), which was due to a strong correlation with the ilio-femoral vessels with no correlation with the thoracic or neck vessels. On multiple linear regression, no correlation between CIMT and global atheroma burden was present (β 0.13 p = 0.45), while the correlation between ABPI and atheroma burden persisted (β −0.45 p = 0.005).

Conclusion

ABPI but not CIMT correlates with global atheroma burden as measured by whole body contrast enhanced magnetic resonance angiography in a population with symptomatic peripheral arterial disease. However this is primarily due to a strong correlation with ilio-femoral atheroma burden.

Aneurysmal remodeling in the circle of Willis after carotid occlusion in an experimental model

Carotid occlusions are associated with de novo intracranial aneurysm formation in clinical case reports, but this phenomenon is not widely studied. We performed bilateral carotid ligation (n=9) in rabbits to simulate carotid occlusion, and sham surgery (n=3) for control. Upon euthanasia (n=3 at 5 days, n=6 at 6 months post ligation, and n=3 at 5 days after sham operation), vascular corrosion casts of the circle of Willis (CoW) were created. Using scanning electron microscopy, we quantified gross morphologic, macroscopic, and microscopic changes on the endocasts and compared findings with histologic data. At 5 days, CoW arteries of ligated animals increased caliber. The posterior communicating artery (PCom) increased length and tortuosity, and the ophthalmic artery (OA) origin presented preaneurysmal bulges. At 6 months, calibers were unchanged from 5 days, PComs further increased tortuosity while presenting segmental dilations, and the OA origin and basilar terminus presented preaneurysmal bulges. This exploratory study provides evidence that flow increase after carotid occlusion produces both compensatory arterial augmentation and pathologic remodeling such as tortuosity and saccular/fusiform aneurysm. Our findings may have considerable clinical implications, as these lesser-known consequences should be considered when managing patients with carotid artery disease or choosing carotid ligation as a therapeutic option.

Hemocoagulase atrox reduces vascular modeling in rabbit carotid artery adventitia

OBJECTIVE

This study aimed to compare the effects of hemocoagulase atrox and cauterization hemostasis on intimal hyperplasia and explore the effect of hemocoagulase atrox on vascular modeling in rabbit carotid artery adventitia.

METHODS

A total of 27 rabbits were randomly divided into 3 groups (0d, 14d, 28d). They were anaesthetized using an intramuscular injection of phenobarbital sodium (1 ml/kg). The left and right common carotid arteries were exposed and capillary hemorrhaged after blunt dissection of the adventitia layers of common carotid arteries. Nine rabbits in each group were again randomly divided into 3 groups, in which animals were respectively treated with hemocoagulase (2 U/ml), cauterization (power = 40 w) and saline (as control). Groups of animals were euthanized at 0, 14 and 28 days after surgery. The samples were equally divided in the middle of the adventitia removal section to obtain equal parts for histologic, immunohistochemical and molecular biologic analysis. The vascular repair after adventitial stripping was observed by HE staining, Masson staining and transmission electron microscopy. The expression of carotid MCP-1, PCNA, TGF-β1, α-SMA and VEGF were measured at different time points by RT-PCR and immunohistochemical staining.

RESULTS

HE staining and Masson staining showed that hemocoagulase atrox had a significantly stronger effect on reducing intimal hyperplasia than the cauterization after 14 and 28 days. The results of RT-PCR showed that the expression of MCP-1, TGF-β1, α-SMA and VEGF in hemocoagulase atrox-treated animals were lower than that of cauterization-treated animals.

CONCLUSION

Our results suggested that hemocoagulase atrox as a topical hemostatic is safety and efficiently and it can accelerate adventitia restoration and decrease intimal proliferation.

Evaluation of a novel thermosensitive heparin-poloxamer hydrogel for improving vascular anastomosis quality and safety in a rabbit model

Despite progress in the design of advanced surgical techniques, stenosis recurs in a large percentage of vascular anastomosis. In this study, a novel heparin-poloxamer (HP) hydrogel was designed and its effects for improving the quality and safety of vascular anastomosis were studied. HP copolymer was synthesized and its structure was confirmed by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (¹H-NMR). Hydrogels containing HP were prepared and their important characteristics related to the application in vascular anastomosis including gelation temperature, rheological behaviour and micromorphology were measured. Vascular anastomosis were performed on the right common carotid arteries of rabbits, and the in vivo efficiency and safety of HP hydrogel to achieve vascular anastomosis was verified and compared with Poloxamer 407 hydrogel and the conventional hand-sewn method using Doppler ultrasound, CT angiograms, scanning electron microscopy (SEM) and histological technique. Our results showed that HP copolymer displayed special gel-sol-gel phase transition behavior with increasing temperature from 5 to 60 °C. HP hydrogel prepared from 18 wt% HP solution had a porous sponge-like structure, with gelation temperature at approximately 38 °C and maximum elastic modulus at 10,000 Pa. In animal studies, imaging and histological examination of rabbit common jugular artery confirmed that HP hydrogel group had similar equivalent patency, flow and burst strength as Poloxamer 407 group. Moreover, HP hydrogel was superior to poloxamer 407 hydrogel and hand-sewn method for restoring the functions and epithelial structure of the broken vessel junctions after operation. By combining the advantages of heparin and poloxamer 407, HP hydrogel holds high promise for improving vascular anastomosis quality and safety.

The multifunctional Ca²⁺/calmodulin-dependent kinase IIδ (CaMKIIδ) regulates arteriogenesis in a mouse model of flow-mediated remodeling

Objective

Sustained hemodynamic stress mediated by high blood flow promotes arteriogenesis, the outward remodeling of existing arteries. Here, we examined whether Ca²⁺/calmodulin-dependent kinase II (CaMKII) regulates arteriogenesis.

Methods and Results

Ligation of the left common carotid led to an increase in vessel diameter and perimeter of internal and external elastic lamina in the contralateral, right common carotid. Deletion of CaMKIIδ (CaMKIIδ−/−) abolished this outward remodeling. Carotid ligation increased CaMKII expression and was associated with oxidative activation of CaMKII in the adventitia and endothelium. Remodeling was abrogated in a knock-in model in which oxidative activation of CaMKII is abolished. Early after ligation, matrix metalloproteinase 9 (MMP9) was robustly expressed in the adventitia of right carotid arteries of WT but not CaMKIIδ−/− mice. MMP9 mainly colocalized with adventitial macrophages. In contrast, we did not observe an effect of CaMKIIδ deficiency on other proposed mediators of arteriogenesis such as expression of adhesion molecules or smooth muscle proliferation. Transplantation of WT bone marrow into CaMKIIδ−/− mice normalized flow-mediated remodeling.

Conclusion

CaMKIIδ is activated by oxidation under high blood flow conditions and is required for flow-mediated remodeling through a mechanism that includes increased MMP9 expression in bone marrow-derived cells invading the arterial wall.

Increasing echogenicity of diffuse circumferential thickening ("macaroni sign") of the carotid artery wall with decreasing inflammatory activity of Takayasu arteritis

We report a case of sonographic follow-up showing brightening of the diffuse circumferential thickening (halo) of the carotid artery wall (the so-called "macaroni sign") in a patient with decreasing inflammatory activity of Takayasu arteritis over a 6-month period. Sonographic follow-up in patients with Takayasu arteritis may be a useful complementary tool for evaluation of inflammatory activity. Besides a reduction of halo diameter, an increase in wall echogenicity appears to be a sign of decreasing inflammation.

[Types and incidence of intravital reactions in cases of suicidal hanging]

In the years 1980-2000 a total of 302 cases of suicidal hanging were analysed at the Department of Forensic Medicine, Medical University of Białystok. In 140 cases (46.36%) the knot was situated on the neck. In 131 corpses 206 intravital reactions were revealed. Descending incidence of the reactions was as follows: petechial subcutaneous facial and palpebre hemorrhages (33.5%), hemorrhages of muscules sternocleidomustoideus (18.4%), hemorrhages within ligature furrow (11.6%), vertebral cervical fracture (0.7%). In overall material 71.8% were sober persons presenting intravital reactions of the cervical organs to ligature. During autopsy examination skin sections were excised from ligature furrow, muscules sternocleidomustoideus and the carotid artery and then stained with hematoxilin-eosin, orcein, Fuller staining and alcian blue. The carotid artery sections were examined in scanning electron microscope. Macroscopically revealed intravital reactions were fully confirmable by scanning electron microscopic examination. Furthermore, in cases with negative macroscopic image lesions of the common carotid arteries were detected.

Cytokine polymorphisms associated with carotid intima-media thickness in stroke patients

BACKGROUND AND PURPOSE

Carotid intima-media thickness (IMT) reflects generalized atherosclerosis and is predictive of future vascular events. Evidence exists that carotid IMT is heritable, and genetic studies can provide clues in the pathogenesis of atherosclerosis.

METHODS

We recruited 470 white ischemic stroke patients, measured common carotid artery (CCA) IMT, and analyzed 54 polymorphisms with suspected roles in atherosclerosis.

RESULTS

Among the polymorphisms tested, the angiotensin-converting enzyme insertion/deletion, osteopontin (OPN) T-443C, monocyte chemoattractant protein-1 (MCP-1) G-927C, and MCP-1 A-2578G polymorphisms were associated with CCA-IMT in age-gender-adjusted analysis. In multivariate analysis, the association between the OPN and MCP-1 polymorphisms remained significant. The OPN-443C allele was associated with increased IMT in the dominant model (0.053 mm for the TC and CC genotypes; P=0.001). The MCP-1-927C allele was associated with increased IMT in the additive model (0.040 mm for each C allele; P=0.001), and the MCP-1-2578 G allele was associated with decreased IMT in the recessive model (0.088 mm for the GG genotype; P=0.002).

CONCLUSIONS

The OPN and MCP-1 genes, coding for 2 cytokines with known roles in atherosclerosis, may contribute to increased carotid IMT and warrant further study.

Characteristics and baseline clinical predictors of future fatal versus nonfatal coronary heart disease events in older adults: the Cardiovascular Health Study

BACKGROUND

Although >80% of annual coronary heart disease (CHD) deaths occur in adults aged >65 years and the population is aging rapidly, CHD event fatality and its predictors in the elderly have not been well described.

METHODS AND RESULTS

The first myocardial infarction (MI) or CHD death among the 5888 adults aged > or =65 years occurring during enrollment in the Cardiovascular Health Study during 1989-2001 was identified and adjudicated. Characteristics measured at examinations before the event were examined for associations with case fatality (death before hospitalization or hospital discharge) and for differences in predictors by demographics or clinical history. During a median follow-up of 8.2 years, 985 CHD events occurred, of which 30% were fatal. Case fatality decreased slightly over time, ranging from 28% to 30% per year in the early 1990s versus 23% by 2000-2001; with adjustment for age at MI and gender, there was a 6% lower odds of fatality with each successive year (odds ratio [OR], 0.94; 95% confidence interval [CI], 0.90 to 0.98). Case fatality was similar by race and gender but higher with age and prior CHD (MI, angina, or revascularization). When considered alone, many subclinical disease measures, such as common carotid intima-media thickness, ankle-arm index, left ventricular mass by ECG, and a major ECG abnormality, and traditional risk factors, such as diabetes and hypertension, were associated with fatality. In multivariable analysis, independent predictors of fatality were prior congestive heart failure (OR, 3.20; 95% CI, 2.32 to 4.41), prior CHD rather than only history of MI (OR, 2.51; 95% CI, 1.84 to 3.43), diabetes (OR, 1.66; 95% CI, 1.10 to 2.31), and age (OR, 1.21 per 5 years; 95% CI, 1.07 to 1.37), adjusted for gender and each other. Prior congestive heart failure, regardless of left ventricular systolic function, age, gender, or prior CHD, conferred a > or =3-fold increased risk of fatality in almost all subgroups.

CONCLUSIONS

Among community-dwelling older adults, CHD case fatality remains substantial, with easily identifiable risk factors that may be different from those that predict incident disease. In the elderly in whom the risk/benefit of therapies may be influenced by multiple competing comorbidities and care needs, risk stratification possibly may be improved further by focusing more aggressive care on specific patients, especially those with a history of congestive heart failure or prior CHD.

The 5-hydroxytryptamine2A receptor antagonist sarpogrelate hydrochloride inhibits acute platelet aggregation in injured endothelium

In this study, the effect of sarpogrelate hydrochloride, a 5-hydroxytryptamine2A receptor antagonist, on platelet aggregation at the site of injured carotid artery endothelium was examined. The rat common carotid artery was clamped for 30 min to induce endothelial injury. Sarpogrelate hydrochloride was administered before and after the injury, and the effects were compared with those in rats receiving sham operation only and those receiving clipping injury but no sarpogrelate hydrochloride. The animals were killed 24 h after the procedure. The common carotid artery was examined by scanning electron microscopy and stained immunochemically for factor VIII. Sarpogrelate hydrochloride treatment was associated with reduced aggregation of platelets on electron microscopy and lower expression of factor VIII at the injured intima. Sarpogrelate hydrochloride has an inhibitory effect on platelet aggregation at the intima in the acute stage after injury, suggesting that this drug may be used to prevent early ischaemic complications after surgical or endovascular arterial intervention.

Atherogenic region and diet diminish glycocalyx dimension and increase intima-to-media ratios at murine carotid artery bifurcation

It was hypothesized that endothelial glycocalyx perturbation contributes to increased vulnerability of the arterial wall exposed to atherogenic risk factors. Glycocalyx and intima-to-media ratios (IMR) were studied at a low- and a high-risk region within the murine carotid artery (common region) and internal carotid branch (sinus region) in control C57BL/6J (C57BL6) and age-matched C57BL/6J/apoE*3-Leiden (apoE*3; on an atherogenic diet) mice. Electron micrographs revealed significantly thinner glycocalyces [73 (SD 36) vs. 399 (SD 174) nm, P < 0.05] and greater IMR [0.096 (SD 0.045) vs. 0.044 (SD 0.023), P < 0.05] at the sinus region of C57BL6 mice than in the common region. Thinner glycocalyces [100 (SD 27) vs. 399 (SD 174) nm, P < 0.05] and greater IMR [0.071 (SD 0.024) vs. 0.044 (SD 0.023), P < 0.05] were also observed in the common region of age-matched apoE*3 mice on an atherogenic diet for 6 wk vs. C57BL6 mice on a normal diet. Greater IMR were due to greater intima layers, without significant changes in media layer dimension. In addition, atherogenic diet resulted in increased endothelial cell thickness at the sinus region [0.85 (SD 0.49) vs. 0.53 (SD 0.28) μm, P < 0.05] but not at the common region [0.66 (SD 0.37) vs. 0.62 (SD 0.32) μm]. It is concluded that both regional and diet-induced increases in atherogenic risk are associated with smaller glycocalyx dimensions and greater IMR and that vascular sites with diminished glycocalyx are more vulnerable to proinflammatory and atherosclerotic sequelae.

Transendothelial migration of ferric ion in FeCl3 injured murine common carotid artery

INTRODUCTION/OBJECTIVES

Adventitial application of FeCl(3) causes endothelial injury, platelet aggregation, and a rapid onset of thrombus formation. The transmigration pathway of the ferric ion has not been definitively identified. Using a combination of TEM and X-ray elemental analysis, this study aims to elucidate the endothelial pathway of ferric ion migration in carotid artery.

METHODS AND RESULTS

Vascular injury was induced by placing a Whatman #1 filter paper strip saturated with 10% FeCl(3) over the common carotid artery in male C57BL/6 mice for 3 min. After rinsing in saline, the mice were terminated at 10 or 30 min. The FeCL(3) exposed segments of the common carotid artery were dissected, and processed for TEM. Thrombus formation was observed in all cases. Endothelial and smooth muscle injuries were observed in segments of the vessel in direct contact with the oxidant. The endothelial injury ranged from minimal damage to total denudation. The basal endothelial surface adjacent to the internal elastic lamina showed accumulation of electron opaque vesicles. The membrane enclosed particles transmigrated across the endothelium and exocytosed into the lumen. The nature of the particles shown by STEM/EDS was rich in ferric ion. Elemental analysis also showed that some ferric oxide aggregates formed near the developing thrombus in the vascular lumen.

CONCLUSION

Our results showed the ferric ion permeated the endothelial basal lamina before entering the arterial lumen via endocytic-exocytic pathway. This study provides an ultrastructural framework for future analysis of the adluminal and luminal injuries in this model.

Mice carrying a R142C Notch 3 knock-in mutation do not develop a CADASIL-like phenotype

CADASIL (Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy, MIM 125310) is a genetic vascular dementia disease that is linked to missense mutations, small in-frame deletions, and splice site mutations in the human Notch 3 gene. Here we describe the generation of a mouse knockin model for one of the most prevalent CADASIL mutations, an arginine to cysteine transition at position 141, R141C, which corresponds to mutation R142C in mouse NOTCH 3. CADASIL(R142C) mice show no apparent CADASIL-like phenotype after histological and MRI analysis. The NOTCH 3 (R142C) receptor is processed normally and does not appear to accumulate the ectodomain, which has been observed in CADASIL patients. We discuss possible reasons for the different outcomes of the same germline CADASIL mutation in mice and humans.

Insulin resistance and carotid atherosclerosis in 221 patients with potential hyperglycemia

OBJECTIVE

To investigate the relationship between insulin resistance and carotid atherosclerosis in patients with potential hyperglycemia.

METHODS

A total of 221 patients were recruited among those with potential hyperglycemia. All participants underwent physical examination, medical history interview, and 75 g oral glucose tolerance test. Venous blood was sampled for measurement of insulin and cholesterol levels. The intima-media thickness (IMT) in bilateral common carotid arteries was observed by B-mode ultrasound. Insulin resistance index was calculated by homeostasis model assessment (HOMA-IR). Subjects were stratified in quintiles according to HOMA-IR values. Risk factors and atherosclerotic parameters were analyzed.

RESULTS

With HOMA-IR value increase, incidence of impaired glucose tolerance, diabetes mellitus, hypertension, and coronary artery disease increased, the levels of triglyceride (TG), low density lipoprotein cholesterol (LDL-C), fasting plasma glucose, 2 hour plasma glucose, and fasting insulin increased as well, while the level of high density lipoprotein cholesterol (HDL-C) decreased. Meanwhile, all atherosclerotic parameters increased. Multivariate regression analysis showed that TG, total cholesterol, HDL-C, LDL-C levels, and ln(HOMA-IR) were related to IMT, hence were risk factors for IMT increase.

CONCLUSION

Insulin resistance is implicated in atherogenesis.

A Pilot Study Into Measurements of Markers of Atherosclerosis in Periodontitis

BACKGROUND

Periodontitis may be a possible risk factor for atherosclerosis. The current pilot study explored arterial wall thickness and other variables associated with atherosclerosis in healthy subjects with and without periodontitis.

METHODS

Patients with moderate (N = 34) and severe periodontitis (N = 15) and controls (N = 14) were recruited. Intima media thickness (IMT) of the common carotid arteries (CCA), internal carotid arteries (ICA), and bifurcations of carotid arteries (BCA) was estimated bilaterally using B-mode ultrasound. An overall IMT was calculated as the mean of these six measurements. C reactive protein (CRP), fibrinogen, and von Willebrand factor (vWf) were measured in plasma as indicators of systemic inflammation and atherosclerotic disease. Microalbuminuria was determined as a marker of endothelial cell dysfunction.

RESULTS

IMT for CCA were 0.64, 0.68, and 0.69 mm for control, moderate, and severe periodontitis, respectively (not significant). IMT for BCA did not vary among groups. IMT of ICA was largest for severe periodontitis (0.81 mm); corresponding values for controls and moderate periodontitis were 0.58 and 0.55 mm, respectively (P= 0.023). Severe periodontitis patients had an overall IMT of 0.76 mm, while moderate periodontitis patients and controls had lower values (0.64 and 0.65 mm, respectively; P= 0.153). After adjusting for potential confounding factors, the increased IMT for ICA in severe periodontitis was also significant (Padj = 0.040). CRP (P= 0.020, Padj = 0.050) and vWf (P= 0.019, Padj = 0.013) were higher in periodontitis than controls; microalbuminuria was not different between groups. Power calculations suggest that a 4-fold expansion of the severe patient and control groups will result in a high chance (power level 80%) that a clinically significant association between the overall IMT and periodontitis will be observed.

CONCLUSION

The present pilot study indicates that a full study investigating the relationship between periodontitis and atherosclerosis is warranted.

Asymptomatic carotid atherosclerosis is associated with circulating chlamydia pneumoniae DNA in younger normotensive subjects in a general population survey

OBJECTIVE

Chlamydia pneumoniae infection has been associated with atherosclerosis, but serodiagnosis is unreliable in predicting vascular infection. Direct detection of circulating chlamydial DNA in peripheral blood mononuclear cells (PBMCs) was thus evaluated as a marker for cardiovascular risk in a general population survey using the common carotid intima-media thickness (IMT) as surrogate marker of asymptomatic atherosclerosis.

METHODS AND RESULTS

C pneumoniae DNA in PBMCs was determined by nested polymerase chain reaction and associated with IMT for 1032 healthy participants of a general population survey who were within the highest or lowest IMT distribution quartile. C pneumoniae DNA was more prevalent in those with increased IMT (13.4% versus 10.7%), but this was not significant in univariate and of borderline significance in multivariate analysis. Testing for potential effect modifications by known strong determinants of an increased IMT in group interaction analysis revealed an independent association between C pneumoniae DNA and IMT in normotensive subjects (odds ratio [OR], 2.06; 95% CI, 1.05 to 4.03; P=0.04) and in those <70 years old (OR, 1.84; 95% CI, 1.06 to 3.19; P=0.03).

CONCLUSIONS

Asymptomatic atherosclerosis is associated with circulating C pneumoniae DNA independently of classical cardiovascular risk factors in normotensive subjects and those <70 years old. C pneumoniae has been implicated in atherogenesis. We determined the association of chlamydial DNA in peripheral blood mononuclear cells with the carotid intima-media thickness from 1032 healthy subjects from a general population survey. A stratified group interaction analysis revealed an independent association in normotensive subjects and those <70 years old.

Morphologic changes in neo-intimal proliferation in an experimental aneurysm after coil embolization: effect of factor XIII administration

We investigated histological changes in aneurysmal orifices after embolization with Guglielmi detachable coils (GDCs) and determined the effects of the wound-healing factor, factor XIII, on promoting intimal proliferation by scanning electron microscopy (SEM). GDC embolization was performed in an experimental model of aneurysm in swine. In the control group (17 aneurysms), the aneurysms were resected immediately after surgery, at 1 and 3 weeks after the procedure. In the factor XIII-administered group (13 aneurysms), the swine received factor XIII postoperatively, and the aneurysms were excised at 1 and 3 weeks. The endothelial cell proliferation changes in the aneurysm orifices in both groups were evaluated by SEM. The histological changes at the orifices began immediately after the procedure, and endothelialization was observed at 1 week. One week after the procedure, the rate of endothelial cell proliferation was significantly higher in the factor XIII group (P<0.05). But no difference was observed at 3 weeks, when endothelialization of the orifices was essentially completed. The process of intimal proliferation after coil embolization was similar to the wound-healing process after vascular intimal injury. Administration of the wound-healing factor, factor XIII, would contribute rapid intimal proliferation and may be effective to facilitate complete obliteration of aneurysms after coil embolization.

Cytokine-Induced Mobilization of Circulating Endothelial Progenitor Cells Enhances Repair of Injured Arteries

Background— The existence of circulating endothelial progenitor cells (CEPCs) has previously been documented. These cells can be mobilized by cytokines and are recruited to sites of injury, where they may participate in tissue repair. In the present study, we examined the hypothesis that mobilization of CEPCs by exogenous granulocyte-colony stimulating factor (G-CSF) enhances repair of injured arteries by facilitating reendothelialization and inhibiting neointima development.

Methods and Results— Male rats were injected daily with 50 μg/kg recombinant human G-CSF or 0.9% NaCl SC for 8 days. On the fifth day of treatment, 1 mL of blood was collected for fluorescence-activated cell sorting analysis of mononuclear cells, and the animals underwent balloon angioplasty of the common carotid artery. The animals were killed at 2 or 4 weeks after injury, and the carotid arteries were harvested and processed for immunohistochemistry, scanning electron microscopy (SEM), and morphometric analysis of endothelialization and neointimal formation. G-CSF increased the number of circulating mononuclear cells that express endothelial cell lineage markers several-fold. SEM and immunohistochemical staining with the endothelial marker, platelet and endothelial cell adhesion molecule-1, showed rapid and nearly complete (>90%) reendothelialization of the denuded vessels in the G-CSF–treated animals compared with <20% in the control animals. Reendothelialization was paralleled by a decrease in inflammation in the vessel wall. Neointima thickness was reduced by ≈60% in the G-CSF–treated animals compared with control animals at 2 and 4 weeks after injury.

Conclusion— We postulate that cytokine-induced mobilization of CEPCs may be a suitable therapeutic strategy for prevention of restenosis after revascularization procedures.

Systemic Lupus Erythematosus

Background— Systemic lupus erythematosus (SLE) patients have a significantly increased risk of coronary heart disease (CHD) that is not fully explained by classic risk factors. Endothelial dysfunction is an early stage in the process of atherogenesis. Our aim was to determine whether endothelial dysfunction occurs in SLE and whether it is associated with the occurrence of classic Framingham risk factors.

Methods and Results— We studied 62 women with SLE (1997 revised criteria) and 38 healthy women. Demographic and risk factor data were collected. In patients, disease activity and treatment-related parameters were also assessed. Endothelial function was assessed by flow-mediated dilation (FMD) in the brachial artery in response to reactive hyperemia. Carotid intima-media thickness (IMT) and the presence of carotid plaques were also assessed in SLE patients. FMD was impaired in SLE patients (median, 3.6%; range, −6.3% to 13.7%; versus median, 6.9%; range, −6.6% to 17.8%, P <0.01). Using multiple regression analysis that included all subjects in which we retained all the classic CHD risk factors, we found that systolic blood pressure ( P =0.019) and SLE ( P =0.017) were significantly associated with impaired FMD. Within SLE patients, IMT showed a negative correlation with percent FMD ( r =−0.37, P <0.01). In stepwise multiple regression of SLE patients only that also included SLE factors and IMT, IMT alone was independently associated with FMD ( P =0.037).

Conclusions— Patients with SLE have endothelial dysfunction that remained significant even after adjustment for other classic CHD risk factors. Within SLE patients, endothelial dysfunction correlates negatively with IMT, another marker of early atherosclerosis. Understanding the mechanism(s) of endothelial dysfunction in SLE may suggest novel strategies for CHD prevention in this context.

Moderately elevated plasma homocysteine impairs functional endothelial recovery following denudation of mouse carotid arteries

Increased total plasma homocysteine is an independent risk factor for cardiovascular disease. This study was designed to determine whether it can impair endothelial function, by examining the recovery of acetylcholine-evoked relaxation following mechanical denudation of the endothelium in the arteries of cystathionine beta-synthase knockout (CbetaS(+/-)) mice. Heterozygous CbetaS(+/-) mice had total plasma homocysteine concentrations significantly higher (8.9 +/- 1.1 micromol/L, n = 12) than strain-matched wild-types (4.6 +/- 0.4 micromol/L, n = 5; P =.003). Left common carotid arteries were denuded of endothelium using a 250-microm polytetrafluoroethylene filament. After 10 days, when the endothelium had completely regrown, relaxation to acetylcholine was measured in precontracted segments of artery. Uninjured right carotid arteries from the same animals served as internal controls. Relaxation to acetylcholine was significantly attenuated in the injured arteries of the CbetaS(+/-) mice, compared to wild-types (P =.017); furthermore, there was a significant negative correlation between sensitivity to acetylcholine and total plasma homocysteine concentration measured in the same animal (r = -0.69, P <.003). These data suggest that even modest homocysteinemia has a deleterious effect on the function of healed endothelium in mouse arteries. This may account for its adverse influence on chronic cardiovascular disease.

Bronchial hyperresponsiveness to methacholine is associated with increased common carotid intima-media thickness in men

BACKGROUND

Respiratory alterations have been associated with subsequent coronary heart diseases in numerous population-based studies. The underlying mechanisms remain largely unknown. The objective of this study was to examine the association between bronchial hyperresponsiveness (BHR) to methacholine (which reflects local inflammation in the bronchus) and common carotid intima-media thickness (CCA-IMT).

METHODS AND RESULTS

As part of the European Community Respiratory Health Survey follow-up, in Paris Center, we assessed BHR to methacholine (> or =20% decrease in FEV1 for a maximum methacholine dose of 4 mg) and measured CCA-IMT by ultrasonography in 255 adults free of cardiovascular diseases aged 29 to 56 years (123 men, 132 women; mean age 44.5 years, 43.5% never smokers). In men, CCA-IMT mean value was higher in subjects with BHR than in those without (0.68+/-0.11 versus 0.62+/-0.09 mm, P=0.002). No association was found in women. Multivariate analysis confirmed the independent association between BHR and CCA-IMT in men (adjusted odds ratio for a 0.10-mm increase in CCA-IMT=2.1, 95% confidence interval: 1.1 to 4.3; P=0.02). These results remained similar after exclusion of asthmatic subjects (n=11). In each strata of smoking status (nonsmoker, ex-smoker, and current smokers), CCA-IMT mean values tended to be higher in subjects with BHR than in those without, although the difference between the 2 groups was more pronounced in current smokers.

CONCLUSIONS

The results of the present study suggest that BHR is independently associated with CCA-IMT in men. The interrelationships between cardiovascular and respiratory alterations should be further investigated.

Measurement of intima-media thickness of common carotid arteries using ultrasound in patients with familial and non-familial hypercholesterolaemia and correlation of intima-media thickness to obesity

Ultrasonographic measurements of the intima-media thickness (IMT) of common carotid arteries (CCA) were taken in 50 patients with familial hypercholesterolaemia (FH) and 57 patients with non-familial hypercholesterolemia (NFH). The lipid profile, body mass index (BMI) and waist-hip ratio (WHR) of each patient were recorded. In FH patients, the IMT was significantly higher in overweight and elevated WHR subgroups compared to the normal with significant correlations between BMI and WHR to the IMT. In NFH patients, the IMT was significantly higher in the elevated WHR compared to the normal subgroup but the correlations between either BMI or WHR to IMT were insignificant. These suggest that the environmentally modified anthropometric indices may have an effect on atherosclerosis in genetically determined hypercholesterolaemia in FH patients.

Synergistic effects of a novel nanoporous stent coating and tacrolimus on intima proliferation in rabbits

To overcome the problem of in-stent restenosis, the concept of local delivery of antiproliferative or immunosuppressive drugs has been introduced into interventional cardiology. Local drug delivery can be achieved by drug-eluting stents coated with polymer surfaces used for controlled drug release. However, several polymer coatings have shown an induction of inflammatory response and increased neointima formation. In the present study, the effect of a new inorganic ceramic nanoporous aluminum oxide (Al(2)O(3)) coating on neointima proliferation and its suitability as a carrier for the immunosuppressive drug tacrolimus have been investigated. 316 L stainless steel coronary stents were coated with a 500 nm thin nanoporous aluminum oxide layer. This ceramic nanolayer was used as a carrier for tacrolimus. Bare stents (n = 6), ceramic coated stents (n = 6), and ceramic coated stents loaded with 60 (n = 7) and 120 mug (n = 6) tacrolimus were implanted in the common carotid artery of New Zealand rabbits. The ceramic coating caused no significant reduction of neointimal thickness after 28 days. Loading the ceramic stents with tacrolimus led to a significant reduction of neointima thickness by 52% for 60 mug (P = 0.047) and 56% for 120 mug (P = 0.036) as compared to the bare stents. The ceramic coating alone as well as in combination with tacrolimus led to a reduced infiltration of lymphocytes and macrophages in the intima in response to stent implantation. Ceramic coating of coronary stents with a nanoporous layer of aluminum oxide in combination with tacrolimus resulted in a significant reduction in neointima formation and inflammatory response. The synergistic effects of the ceramic coating and tacrolimus suggest that this new approach may have a high potential to translate into clinical benefit.

Coaxial double-tubular compliant arterial graft prosthesis: time-dependent morphogenesis and compliance changes after implantation

In order to reduce the compliance mismatch between the native artery and the artificial graft, we have developed a coaxial double-tubular compliant graft, using multiply micropored segmented polyurethane (SPU) thin films, which mimics the relationship between the intraluminal pressure and vessel internal diameter (P-D) of the native artery (termed "J" curve). The graft was coaxially assembled by inserting a high-compliance inner tube with a heparin-immobilized photocured gelatin coating layer into a low-compliance outer tube with a photocured hydrophilic polymer coating layer. Twenty-eight coaxial double-tubular compliant grafts were implanted into the canine common carotid arteries in an end-to-end fashion for up to 12 months. The overall patency rate was 86% (24/28), and neither rupture nor aneurysmal formation was observed. A neoarterial wall was formed via transanastomotic and transmural tissue ingrowth, resulting in neoarterial tissue formation on the luminal surface and into the intertubular space of the double-tubular graft, accompanied by mainly myofibroblasts and inflammatory cells in the early stage and endothelialization and collagen-rich extracellular matrices in the late stage of implantation. Surrounding-tissue adhesion with the outer tube was prevented by the hydrophilic polymer coating. Although the J curve of the implanted prototype model was preserved 1 month after implantation, the impaired J curves were observed because of tissue ingrowth and tissue adhesion between the outer surface of the inner tube and the surrounding tissues 3 and 6 months after implantation. At 12 months after implantation, however, the implanted coaxial double-tubular graft exhibited high compliance due to biodegradation of the SPU films.

A novel S-nitrosothiol causes prolonged and selective inhibition of platelet adhesion at sites of vascular injury

OBJECTIVE

Platelet adhesion to areas of endothelial denudation following angioplasty is an important factor contributing to the limitations of this technique. Lipophilic S-nitrosothiols like S-nitroso-N-valerylpenicillamine (SNVP) are novel nitric oxide (NO) donor drugs with anti-platelet and vasodilator properties that are selective for areas of endothelial denudation. Here we assess the inhibitory effect of SNVP on platelet adhesion to angioplastied rabbit carotid arteries.

METHODS

A rabbit model was used to measure adhesion of radiolabelled platelets to carotid arteries following balloon angioplasty. The effects of SNVP were compared to the conventional NO donor, nitroglycerin (NTG). Electron microscopy was used to visualize adhering platelets.

RESULTS

Angioplasty resulted in endothelial denudation with only a modest reduction in vessel contractility. In vivo administration of NTG and SNVP (both 200 nmol) prevented the hyper-aggregability (approximately 20%) of circulating platelets caused by angioplasty. However, bolus NTG failed to inhibit adhesion of radiolabelled platelets 30 min after angioplasty, despite inducing a transient 30% reduction in systemic blood pressure. In contrast, equimolar SNVP had little effect on blood pressure but markedly inhibited platelet adhesion (62% compared to control; P=0.003). Platelet adhesion was confirmed with electron microscopy.

CONCLUSION

The prolonged effects of SNVP at sites of endothelial damage suggest that novel S-nitrosothiols might offer a means of targeted delivery of an antiplatelet agent to areas of vascular injury.

Carotid labyrinth of amphibians

The amphibian carotid labyrinth is a characteristic maze-like vascular expansion at the bifurcation of the common carotid artery into the internal and external carotid arteries. The carotid labyrinths of anurans are spherical and those of urodeles are oblong. In the intervascular stroma of both anuran and urodelan carotid labyrinths, the glomus cells (type I cells, chief cells) are distributed singly or in clusters between connective tissue cells and smooth muscle cells. In fluorescence histochemistry, the glomus cells emit intense fluorescence for biogenic monoamines. In fine structure, the glomus cells are characterized by a number of dense-cored vesicles in their cytoplasm. The glomus cells have long, thin cytoplasmic processes, some of which are closely associated with smooth muscle cells, endothelial cells, and pericytes. Afferent, efferent, and reciprocal synapses are found on the glomus cells. The morphogenesis of the carotid labyrinth starts in the larvae at the point where the carotid arch descends to the internal gills. Through the early stages of larval development, the slightly expanded region of the external carotid artery becomes closely connected with the carotid arch. By the end of the foot stage, the expanded region becomes globular, and at the final stage of metamorphosis the carotid labyrinth is close to its adult form. In fine structure, the glomus cells appear as early as the initial stage of larval development. At the middle stages of development, the number of dense-cored vesicles increases remarkably. Distinct afferent synapses are found in juveniles, although efferent synapses can be seen during metamorphosis. The carotid labyrinth is innervated by nerve fibers containing several kinds of regulatory neuropeptides. Double-immunolabeling in combination with a multiple dye filter system demonstrates the coexistence of two different neuropeptides. The amphibian carotid labyrinth has been electrophysiologically confirmed to have arterial chemo- and baroreceptor functions analogous to those of the mammalian carotid body and carotid sinus. The ultrastructural characteristics of the glomus cells during and after metamorphosis suggest that the glomus cells contribute to the chemoreception after metamorphosis. The three-dimensional fine structure of vascular corrosion casts suggests that the amphibian carotid labyrinth has the appropriate architecture for controlling vascular tone and the findings throughout metamorphosis reveal that the vascular regulatory function begins at an early stage of metamorphosis. In addition, immunohistochemical studies suggest that the vascular regulation in the carotid labyrinth is under peptidergic innervation. Thus, the multiple functions of the carotid labyrinth underline the importance of this relatively small organ for maintenance of homeostasis and appropriate blood supply to the cephalic region.

Inter-individual variations in wall shear stress and mechanical stress distributions at the carotid artery bifurcation of healthy humans

Fluid shear stress and mechanical wall stress may play a role in the formation of early atherosclerotic lesions, but these quantities are difficult to measure in vivo. Our objective was to quantify these parameters in normal subjects in a clinical setting, and to define regions of low wall shear stress and high mechanical stress. The right carotid bifurcations of five healthy male volunteers were investigated using a novel non-invasive technique which integrates magnetic resonance angiography, ultrasonography, tonometry and state-of-the-art computational fluid dynamics and solid mechanics models. Significant inter-subject variations in patterns as well as magnitude of wall shear stress and mechanical stress were found. In spite of individual variabilities, this study revealed that some regions of the artery wall are exposed simultaneously to low wall shear stress and high mechanical stress and that these regions correspond to areas where atherosclerotic plaque develops. The coexistence of regions of low wall shear stress and high tensile stress may be an important determinant of the formation of atheroma in human arteries.

Role of echocardiography and carotid ultrasonography in stratifying risk in patients with essential hypertension: the Assessment of Prognostic Risk Observational Survey

BACKGROUND

Echocardiography and carotid ultrasonography, by providing a more accurate assessment of cardiac and vascular damage related to hypertension, may lead to a more precise stratification of the global cardiovascular risk. However, current guidelines do not recommend systematic use of ultrasound examination of heart and large arteries in evaluating the cardiovascular risk in patients with hypertension.

OBJECTIVE

To assess the impact of echocardiography and carotid ultrasonography on global risk stratification in hypertensive patients classified as being at low or medium risk according to routine clinical work-up as suggested by current hypertension guidelines.

METHODS

Among 8502 consecutive patients screened at 44 outpatient hypertension hospital clinics in different parts of Italy, 1074 untreated individuals with low-to-medium risk essential hypertension were identified on the basis of the diagnostic routine procedures suggested by 1999 World Health Organization/International Society of Hypertension guidelines: medical history, physical examination and clinic blood pressure measurement; routine blood chemistry and urine analysis; electrocardiogram. The extent of risk for the 1074 individuals was reassessed by adding the results of ultrasound examinations of heart and carotid arteries: left ventricular hypertrophy (defined as left ventricular mass index > 120 g/m(2) in men and > 100 g/m(2) in women), carotid intima-media thickening (defined as diffuse thickening if >or= 0.8 mm), and presence of plaque (defined as focal thickening > 1.3 mm).

RESULTS

According to routine classification, 18.7% (n = 201) of the 1074 patients were considered at low risk and 81.3% (n = 873) at medium risk. A marked change in risk stratification was obtained when ultrasound markers of target-organ damage were taken into consideration: the proportion of low-risk patients decreased to 11.1%, and that of medium risk patients to 35.7%, whereas more than 50% of the patients previously classified at low-medium risk were found to be at high absolute risk. According to a multivariate analysis, age, grade of hypertension, male sex, and serum cholesterol concentration were the variables with the greatest impact on risk class change.

CONCLUSIONS

Ultrasound assessment of the heart and carotid wall helps to obtain a more valid assessment of global cardiovascular risk in hypertensive patients without evidence of target-organ damage after routine examination.

Mechanical properties and structure of carotid arteries in mice lacking desmin

OBJECTIVE

Our aim was to determine in desmin homozygous mutant mice the viscoelastic properties, the mechanical strength and the structure of the carotid artery.

METHODS

To assess the viscoelastic properties of large arteries, we have performed an in vivo analysis of the diameter-, and distensibility-pressure curves of the common carotid artery (CCA) in homozygous (Des -/-), heterozygous (Des +/-) and wild-type (Des +/+) mice. To evaluate the mechanical strength, we have measured the in vitro intraluminal pressure producing the rupture of the carotid artery wall. The structure analysis of the arterial wall was based on histology and electronic microscopy.

RESULTS

A lower distensibility and an increase of arterial wall viscosity were observed in Des -/- compared with Des +/+. Arterial thickness of Des -/- was similar to those of Des +/+, without changes in elastin and collagen contents. Electron microscopy revealed that the perimeter of cellular fingerlike-projections was smaller in Des -/-, indicating that the cells have lost part of their connections to the extracellular matrix. The rupture pressure was significantly lower in Des -/- (1500+/-200 mmHg) compared with Des +/+ (2100+/-80 mmHg) indicating a lower mechanical strength of the vascular wall. No significant difference was found between Des +/- and Des +/+.

CONCLUSION

The desmin is essential to maintain proper viscoelastic properties, structure and mechanical strength of the vascular wall.

A comparison of para-anastomotic compliance profiles after vascular anastomosis: nonpenetrating clips versus standard sutures

PURPOSE

Anastomotic compliance is an important predictive factor for long-term patency of small diameter vascular reconstruction. In this experimental study we compare the compliance of continuous and interrupted sutured vascular anastomoses with those using nonpenetrating clips.

METHODS

Both common carotid arteries in nine goats (average weight, 57 +/- 5.7 kg) were transected, and end-to-end anastomoses were constructed with nonpenetrating clips or polypropylene sutures. The latter were applied with both interrupted and continuous techniques. Intraluminal pressure was measured with a Millar Mikro-tip transducer, and vessel wall motion was determined with duplex ultrasound equipped with an echo-locked wall-tracking system. Diametrical compliance was determined. Environmental scanning electron microscopy was performed on explanted anastomoses.

RESULTS

There was a reduction in anastomotic compliance and associated proximal and distal para-anastomotic hypercompliant zones with the use of all techniques. However, compliance loss was significantly less in those anastomoses with clips and interrupted sutures when compared with continuous suture (P <.001). Furthermore, the total compliance mismatch across anastomoses with continuous sutures was significantly greater than those with clips or interrupted sutures (P <.05). The mean time for constructing clipped anastomoses was 5.7 +/- 1.4 minutes, which was significantly less than either continuous (P <.0001) or interrupted sutures (P <.0001). Furthermore, environmental scanning electron microscopy demonstrated minimal intimal damage with good intimal apposition in the clip group.

CONCLUSION

Anastomoses performed with nonpenetrating clips resulted in improved para-anastomotic compliance profiles and reduced intimal damage when compared with those with polypropylene sutures. These benefits may enhance long-term graft patency by reducing the risk of anastomotic intimal hyperplasia.

Estradiol accelerates reendothelialization in mouse carotid artery through estrogen receptor-alpha but not estrogen receptor-beta

BACKGROUND

The atheroprotective effect of 17beta-estradiol (E(2)) has been suggested in women and clearly demonstrated in animals through both an effect on lipid metabolism and a direct effect on the cells of the arterial wall. It has been shown, for example, that E(2) promotes endothelium-dependent relaxation and accelerates reendothelialization in rats. Similar studies have been undertaken in mice to appreciate the molecular mechanism of this process.

METHODS AND RESULTS

We report here a model of electric carotid injury adapted from that described by Carmeliet et al (1997) that allows us to precisely evaluate the reendothelialization process. We demonstrate that E(2) accelerates endothelial regeneration in castrated female wild-type mice. In ovariectomized transgenic mice in which either the estrogen receptor (ER)-alpha or ERbeta gene has been disrupted, E(2) accelerated reendothelialization in female ERbeta knockout mice, whereas this effect was abolished in female ERalpha knockout mice.

CONCLUSIONS

This study demonstrates that ERalpha but not ERbeta mediates the beneficial effect of E(2) on reendothelialization and potentially the prevention of atherosclerosis.

Surface microarchitectural design in biomedical applications: in vivo analysis of tissue ingrowth in excimer laser-directed micropored scaffold for cardiovascular tissue engineering

A micropatterned microporous segmented polyurethane film (20 x 12 mm in size, 30 micrometer thick) with four regions was prepared by excimer laser microprocessing to provide an in vivo model of transmural tissue ingrowth in an open cell-structured scaffold specially designed for cardiovascular tissue engineering. Three microporous regions had the same circular micropores (30 micrometer diameter) but different pore density arrangements (percentage of total pore area against unit area was 0.3%, 1.1%, and 4.5%), and the other region remained nonporous. The covered stent, prepared by wrapping the regionally different density-microporous film on an expandable metallic stent (approximately 3.1 mm in diameter), was delivered to the luminal surface of canine common carotid arteries and placed after expansion of the stent to a diameter of approximately 8 mm using a balloon catheter. At 4 weeks of implantation, all the covered stents (n = 10) were patent. The luminal surfaces of the covered stents were almost confluently endothelialized both in nonporous and microporous regions. Histological examination showed that the neointimal wall was formed by tissue ingrowth from host through micropores (transmural) and anastomotic sites. Thrombus formation occurred frequently in the lowest density porous region and nonporous region. With an increase in pore density, the thickness of the neointimal wall decreased. This study demonstrated how the micropore density of implanted devices influences tissue ingrowth in arterial implantation.

ACE-inhibition promotes apoptosis after balloon injury of rat carotid arteries

OBJECTIVE

Angiotensin II stimulates vascular smooth muscle cell (VSMC) growth, and is considered to be an important mediator of intimal thickening after vascular injury. Recent evidence has indicated that VSMC apoptosis plays a major role in the response to balloon injury, and we therefore examined the effect of angiotensin converting enzyme (ACE)-inhibition on VSMC apoptosis and vascular lesion formation in the rat model of balloon injury.

METHODS

Male Sprague-Dawley rats were subjected to carotid artery balloon injury and randomised to a standard diet or a diet supplemented with 1 mg/ml captopril in the drinking water. Animals were sacrificed 2 and 14 days after injury for assessment of apoptosis and proliferation by in situ terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labelling (TUNEL) and proliferating cell nuclear antigen (PCNA) immunohistochemistry, respectively. At 14 days post injury, vessel cross-sections were subjected to microscopic morphometry and total cell numbers were determined.

RESULTS

At 2 days after balloon injury, captopril-treated animals displayed a significant increase in the percentage of TUNEL-positive VSMCs in the medial area (12 +/- 4% vs. 1 +/- 1%; P < 0.05) as compared to controls. This increase in early apoptosis was associated with decreased intimal cellularity 14 days post injury (238 +/- 47 cells/cross-section vs. 449 +/- 75 cells/cross-section; P < 0.05), and a reduction of neointimal formation (0.13 +/- 0.02 mm2 vs. 0.23 +/- 0.04 mm2; P < 0.05). The fraction of PCNA-positive VSMCs per cross-section 2 or 14 days after injury was not significantly altered by captopril administration.

CONCLUSION

Captopril inhibits neointimal formation in the rat model of arterial injury by mechanisms involving induction of VSMC apoptosis.

Adaptive remodeling of internal elastic lamina and endothelial lining during flow-induced arterial enlargement

Gaps in the internal elastic lamina (IEL) have been observed in arteries exposed to high blood flow. To characterize the nature and consequences of this change, blood flow was increased in the carotid arteries of 56 adult, male, Japanese white rabbits by creating an arteriovenous fistula between the common carotid artery and the external jugular vein. The common carotid artery proximal to the arteriovenous fistula was studied at intervals from 1 hour to 8 weeks after exposure to high flow. In the controls, the IEL showed only the usual, small, physiological holes, 2 to 10 microm in diameter. At 3 days, some of the holes in the IEL had become enlarged, but they could not be detected by scanning electron microscopy, despite manifest endothelial cell proliferation. At 4 days, gaps in the IEL appeared as small, luminal surface depressions, 15 to 50 microm wide. At 7 days, the gaps in the IEL had enlarged and formed circumferential, luminal depressions occupying 15+/-5% of the lumen surface. Endothelial cell proliferation persisted in the gaps while proliferative activity decreased where the IEL remained intact. At 4 weeks, as the artery became elongated and dilated, the gaps in the IEL widened as intercommunicating circumferential and longitudinal luminal depressions occupying 64+/-5% of the lumen surface. At 8 weeks, the rate of elongation and dilatation of the artery slowed and the widening of the gaps in the IEL diminished. Endothelial cells covered the gaps throughout. We conclude that flow-induced arterial dilatation is accompanied by an adaptive remodeling of the intima. The gaps in the IEL permit an increase in lumen surface area while endothelial cell proliferation assures a continuous cell lining throughout.

Alimentary lipemia, postprandial triglyceride-rich lipoproteins, and common carotid intima-media thickness in healthy, middle-aged men

BACKGROUND

Alimentary lipemia has been associated with coronary heart disease and common carotid artery intima-media thickness (IMT). This study was designed to investigate the relations of subclasses of postprandial triglyceride-rich lipoproteins (TRLs) with IMT.

METHODS AND RESULTS

Ninety-six healthy 50-year-old men with an apolipoprotein (apo) E3/E3 genotype underwent an oral fat tolerance test and B-mode carotid ultrasound examination. The apo B-48 and apo B-100 contents of each fraction of TRLs were determined as a measure of chylomicron remnant and VLDL particle concentrations. In the fasting state, LDL cholesterol (P<0.05) and basal proinsulin (P<0. 05) were significantly related to IMT, whereas HDL cholesterol, plasma triglycerides, and insulin were not. In the postprandial state, plasma triglycerides at 1 to 4 hours (P<0.01 at 2 hours), total triglyceride area under the curve (AUC) (P<0.05), incremental triglyceride AUC (P<0.01), and the large VLDL (Sf 60 to 400 apo B-100) concentration at 3 hours (P<0.05) were significantly related to IMT. Multivariate analyses showed that plasma triglycerides at 2 hours, LDL cholesterol, and basal proinsulin were consistently and independently related to IMT when cumulative tobacco consumption, alcohol intake, waist-to-hip circumference ratio, and systolic blood pressure were included as confounders.

CONCLUSIONS

These results provide further evidence for postprandial triglyceridemia as an independent risk factor for early atherosclerosis and also suggest that the postprandial triglyceridemia is a better predictor of IMT than particle concentrations of individual TRLs.

[Ultrastructural changes of arterial wall from different body parts of rats during simulated weightlessness]

OBJECTIVE

To test the nature of remodeling of arteries in different body parts in adapting to local hemodynamic changes induced by tail-suspension.

METHOD

Ultrastructural changes of hindlimb and cerebral arteries from 4-wk tail-suspended (SUS-4), 1-wk recovered (REC-1), and control (CON) rats were studied by transmission electron microscopy.

RESULT

For the hindquarter arteries, like the femoral artery and anterior tibial artery, there were fewer smooth muscle layers, less myofilaments in the smooth muscle cell (SMC), and more intercellular substance in SUS-4 group than in CON group. After 1-wk recovery, the internal elastic lamina of the arteries thickened, the amount of myofilaments in SMC increased, the content of intercellular substance restored, and neoformative SMCs emerged under the endothelium. With respect to arteries in the neck region and the brain, like the common carotid artery and basilar artery, SMCs of contractile phenotype were converted to that of synthetic phenotype, and migration and hyperplasia of SMCs also happened. After 1-wk recovery all these alterations were somewhat restored.

CONCLUSION

It provided further evidence that peripheral effector mechanism might play an important role in the genesis of postflight orthostatic intolerance.

Controlling transplant vasculopathy in cryopreserved vein grafts with polyethylene glycol and glutathione during transport

BACKGROUND

the biological characteristics of cryopreserved allografts are poorly understood, although many factors are known to influence their outcome. This study examines the development of transplant vasculopathy in both fresh and cryopreserved vein allografts and specifically assesses the efficacy of a transport solution containing 10% polyethylene glycol and 10 microM glutathione (PEG/GSH).

METHODS

jugular veins were harvested from control donor rabbits and transplanted as interposition carotid bypass grafts in 30 New Zealand White (NZW) rabbits. Ten received the fresh jugular veins (fresh). Ten animals received jugular veins which had been harvested, transported in a physiological solution, cryopreserved and stored in a standard fashion (cryopreserved). Ten animals received jugular veins which had been harvested, transported in the same solution with the addition of PEG/GSH, cryopreserved and stored in a standard fashion (PEG/GSH). Cryopreserved jugular veins were stored for 6 weeks before transplantation. All animals were sacrificed 28 days postoperatively. Vein grafts were perfusion-fixed and wall dimensions were determined by planimetry.

RESULTS

all transplanted grafts were patent at harvest. The control cryopreserved vein grafts showed a 54% increase in mean intimal thickness (63+/-10 micron vs. 41+/-3 micron p<0.05) but no change in mean medial thickness (125+/-9 micron vs. 119+/-13 micron; p = N.S. ) compared to the fresh allograft. Transport of the grafts in PEG/GSH solution resulted in the abolition of the increase in intimal thickness (41+/-4 micron; p <0.01) associated with cryopreservation without a change in medial thickness (140+/-15 micron; p = N.S.) compared to the cryopreserved allograft.

CONCLUSION

cryopreserved vein grafts develop significant intimal hyperplasia compared to freshly transplanted grafts. The use of PEG/GSH in the transport solution significantly reduces this transplant graft intimal hyperplasia to that which develops in fresh grafts and may lead to improvements in the clinical use of cryopreserved veins.

The electron microscopic morphology of the common carotid artery in rats

The common carotid arteries of normal adult rats were investigated electron-microscopically after tannic acid fixation. This fixation technique yields a better demonstrability of the structures of the connective tissue, the basal laminae and the surface coat of the cell membrane. The common carotid artery represents a vessel of the elastic type. The intima consists of an endothelium and a narrow gap of connective tissue (0.1-1 micron) which contains single collagenous fibrils and small elastic structures. This space is only occasionally as wide as 3 microns, especially beneath gaps of the internal elastic membrane. In these areas, single cells and structures of densely packed filaments are additionally observed which can neither be attributed to collagenous fibrils nor to elastic fibres. The intima is demarcated from the outside by an internal elastic membrane (1 micron) which shows a number of gaps. The media exhibits 3 to 4 elastic membranes without gaps. Smooth muscle cells of the contractile type stretch in an oblique direction between these membranes, i.e. they are not arranged in a circular or spiral manner. Most of their process-rich ends are inserted directly into the elastic material and not via a basal lamina. Processes from these smooth muscle cells, collagenous fibrils and elastic fibres are seen in the intercellular spaces. The muscle cells are occasionally interlinked by gap junctions. The basal lamina does not surround the muscle cells continuously. The adventitia contains bundles of collagenous fibrils, fibrocytes, a few small vessels and nerves with a perineuronal envelope. Nerves could not be demonstrated in the media. The oblique course of the smooth muscle cells and the insertion into the elastic membranes indicate that these cells do not predominantly contribute to changes in the width of the lumen but also serve the stabilisation and resetting of the elastic membranes. Contraction is probably induced by an opening of stretch-dependent Ca2+ channels. Due to the interlinkage with gap junctions, the muscle cells of one layer respond as a functional unit. Our findings provide a morphological basis for elucidating commonly encountered changes, such as smooth muscle migration through a normally interrupted inner elastic lamina.

Takayasu's arteritis diagnosed at the early systemic phase: diagnosis with noninvasive investigation despite normal findings on angiography

We describe a case of Takayasu's arteritis discovered at the early systemic phase. Ultrasonography and computed tomography show thickening of the walls of the superior mesentery and common carotid arteries despite normal findings on angiography. Diagnosis was confirmed by arterial biopsy. We emphasize the importance of noninvasive vascular investigation to support the diagnosis of Takayasu's arteritis.

Nitric oxide synthase inhibition in humans reduces cerebral blood flow but not the hyperemic response to hypercapnia

BACKGROUND AND PURPOSE

Animal studies suggest that nitric oxide (NO) is important in basal cerebral blood flow (CBF) regulation and that it may mediate the vasodilatory response to carbon dioxide. We investigated its role in the human circulation using the NO synthase inhibitor N(G)-monomethyl-L-arginine (L-NMMA).

METHODS

L-NMMA was administered as an intravenous bolus at three doses (1, 3, and 10 mg/kg). CBF was assessed by color velocity ultrasonic imaging of internal and common carotid artery volume flow (ICA flow and CCA flow) and transcranial Doppler ultrasound measurement of middle cerebral artery flow velocity (MCAv). The pressor effect of L-NMMA was controlled for by comparison with noradrenaline titrated to effect an equivalent blood pressure elevation.

RESULTS

L-NMMA produced a dose-dependent reduction in basal mean+/-SD CCA flow from 415.2+/-51.9 to 294+/-56.2 mL/min (at 10 mg/kg) and ICA flow from 268.8+/-59.4 to 226.2+/-72.6 mL/min (P<.005 and P<.05, respectively, comparing areas under the dose-response curve). This was reversed by L-arginine. Mean+/-SD systemic blood pressure rose from 85.2+/-6.4 to 100.8+/-9.6 mm Hg (P<.01). There was no significant reduction in MCAv. There was no significant change in the CBF response to either 6% or 8% carbon dioxide after L-NMMA. Noradrenaline produced a lesser fall in basal CCA flow (12.0%) but had a similar effect on the hypercapnic response.

CONCLUSIONS

Basal NO release is important in controlling human CBF, but intravenously administered L-NMMA does not inhibit the hypercapnic hyperemic response in humans. The discrepancy between CBF and MCAv after L-NMMA administration is consistent with MCA vasoconstriction. Neuronal NO synthase inhibition may be protective in stroke. However, our results suggest that nonselective NO synthase inhibitors such as L-NMMA should be used with caution because they reduce CBF.

The formal pathogenesis of isolated common carotid or innominate arteries: the concept of malseptation of the aortic sac

Deficient connections (= isolation) of the innominate artery or the common carotid artery to the aorta are rare congenital anomalies of the human aortic arch complex that are usually associated with a patent vascular connection between the isolated artery and a pulmonary artery. In the present study we demonstrate chick fetuses with a corresponding anomaly, the isolation of the brachiocephalic artery. In our chick fetuses the left brachiocephalic artery did not arise from the aortic arch, but was connected to the pulmonary trunk proximal (upstream) to the patent left and right ductus arteriosus. These cases are of interest because the presence of a congenital pulmonary-systemic arterial connection proximal (upstream) to the ductus arteriosus cannot be explained by the traditional concept of the morphogenesis of the aortic arch complex. The development of the normal and abnormal branching patterns of the aortic arch arteries is traditionally explained by transformation of the primitive embryonic pharyngeal arch arterial system due to obliteration of some of its vascular segments. Based on this concept, the isolation of an aortic arch artery can be explained by obliteration of vascular segments proximal and distal to this artery, whereas its connection to a pulmonary artery can be explained only by deficient obliteration (persistence) of the distal portion of the right or left sixth pharyngeal arch artery. The connecting "vascular segment" between an isolated aortic arch artery and the pulmonary circulation, therefore, is traditionally interpreted as a patent ductus arteriosus. The formal pathogenesis of congenital pulmonary-systemic arterial connections proximal (upstream) to the ductus arteriosus is discussed. The presented cases of isolation of the brachiocephalic artery are explained by disturbances in the partition of the embryonic aortic sac, possibly due to abnormal development of the "cardiac" neural crest.

Inhibition of von Willebrand factor binding to platelet GP Ib by a fractionated aurintricarboxylic acid prevents restenosis after vascular injury in hamster carotid artery

BACKGROUND

Aurintricarboxylic acid (ATA) prevents von Willebrand factor binding to platelet glycoprotein (GP) Ib, with higher-molecular-weight ATA more effective than the lower-molecular-weight compound. We investigated the effects of high-molecular-weight ATA (Mr=7500), obtained by fractionating commercial ATA, in the injured hamster carotid artery.

METHODS AND RESULTS

Platelet aggregation was induced in vitro with ADP (2.5 micromol/L) or botrocetin (5 microg/mL) in hamster platelet-rich plasma. IC50 values were 348.6+/-22.4 and 8.2+/-3.2 microg/mL, respectively. The endothelium of hamster carotid artery was denuded with a modified catheter. Continuous administration of high-molecular-weight ATA (10, 30, and 100 microg x kg(-1) x h(-1)) with an infusion pump produced antithrombotic effects in a dose-dependent manner, as evaluated by prolongation of time to occlusion. Neointima formation was observed 2 weeks after catheterization, and proliferating smooth muscle cells (SMCs) were identified by the thymidine analogue 5-bromo-2-deoxyuridine (BrdU). Continuous treatment with the compound (100 microg x kg(-1) x h(-1)) with a 2ML1 Alzet infusion pump resulted in a reduction of neointimal area by 38.0+/-8.8% and decreased the BrdU index on days 1 and 7 significantly. DNA synthesis in DDT1MF2 hamster SMCs was also decreased by the compound in a dose-dependent manner. In histological observation, the process of endothelial healing was improved by this treatment with the compound.

CONCLUSIONS

Inhibition of platelet adhesion by von Willebrand factor binding to platelet GP Ib by high-molecular-weight ATA results in the prevention of thrombus formation and the suppression of neointima lesion. In addition, high-molecular-weight ATA has an inhibitory effect on SMC proliferation. This inhibition of both platelet adhesion and SMC proliferation markedly reduced vascular stenosis.

Viscoelastic properties of human arteries. Methodology and preliminary results

In order to study the biomechanical properties of the arterial wall and to compare arteries with different histologic structures, we designed a device that allows testing of arterial segments under near-physiologic conditions. A hydrodynamic generator simulates systolo-diastolic pressures in an open loop. An intraarterial pressure sensor and a sonomicrometer connected to two piezoelectric crystals placed in diametric opposition on the arterial wall allow computer calculation of compliance, stiffness, midwall radial arterial stress, Young modulus, and incremental modulus for a given arterial segment at a given pressure setting. Seven healthy common carotid artery (CCA) segments and seven healthy (superficial) femoral artery (FA) segments were studied immediately after removal from brain-dead donors between the ages of 18 and 35 years. Histologic examination was performed to determine the density of elastic fibers in the arterial wall. Hysteresis was observed in all segments regardless of pressure settings. Compliance was greater and modulus values and stiffness were lower in CCA than in FA. No evidence of structural change was noted after testing in the circulation loop. These preliminary results open the way to a wide variety of applications for our hydrodynamic circulation loop. Experiments will be undertaken to compare the mechanical properties of arteries before and after cryopreservation.

In vivo evaluation of antiplatelet agents in gerbil model of carotid artery thrombosis

BACKGROUND AND PURPOSE

Antiplatelet agents are widely used for the prevention of ischemic stroke. However, their effects on thrombus formation have rarely been evaluated in experimental animals in vivo. We introduce methods for evaluating antithrombotic action in gerbils and the effects of several antiplatelet agents on thrombus formation.

METHODS

In gerbils 8 to 10 weeks of age, we tightly compressed the unilateral common carotid artery for 2 minutes using the device prepared for this purpose to damage the endothelium. Thrombus formation in the damaged artery was observed directly through the microscope for 30 minutes. In six animals, the damaged artery was examined immediately after the experiments by electron microscopy. We studied the effects of antiplatelets by injecting the drugs intravenously 10 minutes before endothelial damage.

RESULTS

In control studies, 70% to 90% of animals developed thrombi after arterial compression. The electron microscopic examination displayed endothelial damage in association with platelet thrombus at the damaged site. Administration of 2 mg/kg aspirin, 3 and 10 mg/kg ticlopidine, and 0.3 and 1.0 mg/kg ibudilast, a novel prostacyclin accelerator, decreased the frequency of thrombus formation significantly, whereas 20 mg/kg aspirin and 20 mg/kg dipyridamole failed to decrease thrombus formation.

CONCLUSIONS

This model is considered useful for evaluating the antithrombotic effects of drugs because of its feasibility and high reproducibility. The present results support the view that a lower dose of aspirin may prevent cerebral vascular accidents as efficiently as a higher dose of aspirin.

Effects of cryopreservation on the viscoelastic properties of human arteries

The purpose of this study was to use our newly developed mock circulation loop to determine the effects of cryopreservation on the common carotid artery (CCA) and the superficial femoral artery (SFA). Fourteen healthy arteries (7 CCA and 7 SFA) harvested from multiple organ donors between the ages of 18 and 35 years were tested before and after cryopreservation at -140 degrees C using dimethyl sulfoxide and the vapor phase of liquid nitrogen. Mean storage time was 4.2 months. The mock pulse rate was 60 beats/min and the following four systolic/diastolic pressures settings were used: 50/110, 80/140, 110/170, and 140/200 mm Hg. Simultaneous measurements of intra-arterial pressure and external arterial diameter were made using an intra-arterial pressure sensor and external piezoelectric sensors. Measured data were used to calculate pulsatility, volumetric compliance, stiffness, midwall radial arterial stress, Young's modulus, and the incremental modulus. After SFA cryopreservation, no significant changes were observed. Conversely, CCA cryopreservation led to a significant decrease in compliance and pulsatility and a significant increase in stiffness. Young's modulus, the incremental modulus, and midwall radial arterial stress did not change significantly. A clearcut decrease in hysteresis was observed after cryopreservation in the CCA. No evidence of structural changes was detected on light and scanning electron microscopy. Baseline findings in this study were consistent with classification of the CCA as an elastic artery and the SFA as a muscular artery. Cryopreservation had no effect on the viscoelastic properties of muscular arteries (SFA). Cryopreservation affected only values related to the cylindrical shape of the elastic arteries (CCA). It had no effect on values related to wall structure.

Seeding of vascular grafts with genetically modified endothelial cells. Secretion of recombinant TPA results in decreased seeded cell retention in vitro and in vivo

BACKGROUND

Seeding of small-diameter vascular grafts with endothelial cells (ECs) genetically engineered to secrete fibrinolytic or antithrombotic proteins offers the potential to improve graft patency rates.

METHODS AND RESULTS

Sheep venous ECs were transduced with a retroviral vector encoding human tissue plasminogen activator (TPA). The ECs were seeded onto 4-mm-ID synthetic (Dacron) grafts. Retention of the seeded ECs was measured 2 hours after placement of the seeded grafts both in vitro in a nonpulsatile flow system and in vivo (in sheep) as femoral and carotid interposition grafts. On exposure to flow in vitro, ECs transduced with TPA were retained at a significantly lower rate (median, 67%) than either untransduced ECs (81%) or ECs transduced with a control retroviral vector producing beta-galactosidase (beta-Gal) (80%) (P < .05 for TPA versus either control). On implantation in vivo, ECs transduced with TPA were retained at a very low rate (median, 0%), significantly less than the retention of ECs transduced with the beta-Gal vector (32%; P < .00001). Decreased in vivo retention of ECs transduced with TPA correlated modestly with increased in vitro cellular passage level (r2 = .48; P < .0001) but not with in vivo blood flow rate (P = .45). Addition of the protease inhibitor aprotinin to the cell culture and graft perfusion media resulted in a significant (P < .05) increase in in vitro retention of ECs transduced with TPA.

CONCLUSIONS

Increased TPA expression significantly decreases seeded EC adherence in vitro and in vivo. Gene therapy strategies for decreasing graft thrombosis may require expression of antithrombotic molecules that lack proteolytic activity.

Complex structure of the common carotid artery of sheep

BACKGROUND

Mechanical properties of blood vessels are dictated by the vessel wall structure. In many large conduit vessels the tunica media is a sheath of circular musculature and the tunica adventitia a layer of fibrous connective tissue with limited longitudinal extensibility. In contrast, the carotid artery of the sheep displays in each tunica a more complex architecture of muscle and connective tissue.

METHODS

Vessels collected from ewes were measured and processed for light microscopy and for transmission electron microscopy.

RESULTS

Layers of histologically different materials are found within the tunica intima, media and adventitia. (1) The tunica media is made of circumferentially arranged muscle cells markedly different at different depths. In the innermost third of the media, muscle cells are small and with irregular profiles, the cells are widely separated, and the extracellular material is abundant and composed mainly of elastic fibres. In the outermost third, muscle cells are larger and with more regular profiles, the cells are relatively close to each other and the extracellular material is sparse and consists mainly of collagen fibrils. (2) A small number of fibroblasts is found in all parts of the media amongst the preponderant muscle cells. (3) The intima contains fibroblast-like cells and longitudinally arranged muscle cells. (4) The adventitia contains a thick layer of collagen and elastic fibres; external to this, it displays a conspicuous musculature, made of large bundles of longitudinal muscle.

CONCLUSIONS

The carotid artery of the sheep presents in all three coats of its wall features which are at variance from those in the better known vessels of small laboratory animals. The presence of many layers of material within the wall, the heterogeneity of the tissues found, and the occurrence of an extensive longitudinal musculature, have important effects on the mechanical properties of the vessel.

Local delivery of vascular endothelial growth factor accelerates reendothelialization and attenuates intimal hyperplasia in balloon-injured rat carotid artery

BACKGROUND

Most strategies designed to reduce restenosis by the use of pharmacological or biological reagents involve direct inhibition of vascular smooth muscle cell (SMC) proliferation. Alternatively, SMC proliferation might be indirectly inhibited if reendothelialization could be specifically facilitated at sites of balloon-induced arterial injury. Accordingly, we investigated the hypothesis that application of an endothelial cell (EC)-specific mitogen to a freshly denuded intimal surface could accelerate reendothelialization and thereby attenuate intimal hyperplasia.

METHODS AND RESULTS

The left carotid artery of 31 Sprague-Dawley rats was subjected to balloon injury, after which 16 rats were treated with a 30-minute incubation with 100 micrograms of vascular endothelial growth factor (VEGF), an EC-specific mitogen. Control animals (n = 15) received a 30-minute incubation with 0.9% saline. At 2 weeks after balloon injury, carotid artery reendothelialization was markedly superior in the VEGF-treated group compared with the control group (14.59 +/- 1.12 versus 7.96 +/- 0.51 mm2, P < 0.005). The extent of reendothelialization measured at 4 weeks after balloon injury remained superior for arteries treated with VEGF (18.04 +/- 0.90 mm2) versus saline (13.42 +/- 0.84 mm2, P < .005). Neointimal thickening was correspondingly attenuated to a statistically significant degree in arteries treated with VEGF versus the control group at both the 2-week and 4-week time points. Immunostaining for proliferating cell nuclear antigen (PCNA) disclosed a threefold increase in PCNA-positive cells in the neointima of control arteries versus VEGF-treated arteries at 2 weeks after injury.

CONCLUSIONS

Application of VEGF, an EC-specific growth regulatory molecule, may be effectively used in vivo to promote reendothelialization and thereby indirectly attenuate neointimal thickening due to SMC proliferation.