Expression of vascular adhesion molecules in saphenous vein coronary bypass grafts

Excessive Adventitial and Perivascular Vascularisation Correlates with Vascular Inflammation and Intimal Hyperplasia

Albeit multiple studies demonstrated that vasa vasorum (VV) have a crucial importance in vascular pathology, the informative markers and metrics of vascular inflammation defining the development of intimal hyperplasia (IH) have been vaguely studied. Here, we employed two rat models (balloon injury of the abdominal aorta and the same intervention optionally complemented with intravenous injections of calciprotein particles) and a clinical scenario (arterial and venous conduits for coronary artery bypass graft (CABG) surgery) to investigate the pathophysiological interconnections among VV, myeloperoxidase-positive (MPO⁺) clusters, and IH. We found that the amounts of VV and MPO⁺ clusters were strongly correlated; further, MPO⁺ clusters density was significantly associated with balloon-induced IH and increased at calciprotein particle-provoked endothelial dysfunction. Likewise, number and density of VV correlated with IH in bypass grafts for CABG surgery at the pre-intervention stage and were higher in venous conduits which more frequently suffered from IH as compared with arterial grafts. Collectively, our results underline the pathophysiological importance of excessive VV upon the vascular injury or at the exposure to cardiovascular risk factors, highlight MPO⁺ clusters as an informative marker of adventitial and perivascular inflammation, and propose another mechanistic explanation of a higher long-term patency of arterial grafts upon the CABG surgery.

Time-dependent pathobiological and physiological changes of implanted vein grafts in a canine model

Although autologous vein grafting is essential, the high vein failure rate and specific clinical interventions are not clear, so a potential treatment is critically needed; thus, complex analyses of the relationship between pathobiological and physiological processes in preclinical are essential. The interposition of the femoral vein was performed in a canine model. Maximized expansion and velocity were measured at 8 weeks post-implantation, and a relative decrease was observed at 12 weeks. However, NI formation and NI/Media ratio significantly increased time dependently, and differences between the mechanical properties were observed. Additionally, RhoA-mediated TNF-α induced by rapid structural changes and high shear stress was confirmed. After adaptation to the arterial environment, vascular remodeling occurred by SMC proliferation and differentiation, apoptosis and autophagy were induced through YAP activity without vasodilation and RhoA activity. Our results show that understanding pathobiological processes in which time-dependent physiological changes contribute to vein failure can lead to a potential strategy. The implanted vein graft within the arterial environment undergoes pathobiological processes through RhoA and YAP activity, leading to pathophysiological changes.

The Anti-Inflammatory Effects of Anacardic Acid on a TNF-α - Induced Human Saphenous Vein Endothelial Cell Culture Model

BACKGROUND AND OBJECTIVE

Coronary bypass operations are commonly performed for the treatment of ischemic heart diseases. Coronary artery bypass surgery with autologous human saphenous vein maintains its importance as a commonly used therapy for advanced atherosclerosis. Vascular inflammation-related intimal hyperplasia and atherosclerotic progress have major roles in the pathogenesis of saphenous vein graft disease.

METHODS

In our study, we investigated the effect of anacardic acid (AA), which is a bioactive phytochemical in the shell of Anacardium occidentale, on atherosclerosis considering its inhibitory effect on NF-κB. We observed relative ICAM-1 and NF-κB mRNA levels by qRT-PCR method in a TNF-α- induced inflammation model of saphenous vein endothelial cell culture after 0.1, 0.5, 1 and 5 μM of AA were applied to the cells. In addition, protein levels of ICAM-1 and NF-κB were evaluated by immunofluorescent staining. The results were compared between different concentrations of AA, and also with the control group.

RESULTS

It was found that 5 μM, 1 μM and 0.5 μM of AA had toxic effects, while cytotoxicity decreased when 0.1 μM of AA was applied both alone and with TNF-α. When AA was applied with TNF-α, there was a decrease and suppression in NF-κB expression compared with the TNF-α group. TNF-α-induced ICAM-1 expression was significantly reduced more in the AA-applied group than in the TNF-α group.

CONCLUSION

In accordance with our results, it can be said that AA has a protective role in the pathogenesis of atherosclerosis and hence in saphenous vein graft disease.

Phlebosclerosis in lower extremities veins - a systematic review

Phlebosclerosis is a venous wall degenerative disease which has gained little popularity in the literature due to its uncertain clinical significance. The objective of this review is to evaluate the epidemiology, etiology and clinical significance of phlebosclerosis in lower extremities veins, particularly the effect of preexisting phlebosclerosis of the great saphenous vein on vein graft patency. Medline was searched from inception until November 1, 2019. Reference lists of included studies were scanned. Only articles published after 1949 were included. Two reviewers independently screened titles/abstracts and full-text papers for any study design in relation to phlebosclerosis in lower extremities veins and abstracted data. A total of 16 Cohort studies and one case-control study (3708 participants, mean age 61.8 years, 59.3 % men, and 40.7 % women) were included after screening 317 titles and abstracts, and 80 full-text articles. The incidence of phlebosclerosis ranged from 1.5-9.7 % depending on the radiological features. On the contrary, the incidence of the phlebosclerotic great saphenous vein prior to its use as a vein graft was 26.9-91 % on histological examination. The small saphenous vein was the most common location of phlebosclerosis followed by the great saphenous vein. There is a link between phlebosclerosis and age, venous insufficiency and haemodialysis. As for the vein graft patency seven studies demonstrated a correlation between preexisting phlebosclerosis and vein graft stenosis, whereas three studies failed to prove any association. In conclusion, the radiological incidence of phlebosclerosis depended on the ultrasound findings. Its presence in the great saphenous vein prior to its use as a vein graft is established on histological examination. The small saphenous vein is mainly affected. Risk factors included age, haemodialysis, and venous insufficiency. Preexisting wall thickness of the great saphenous vein graft seemed to affect negatively its patency in bypass surgery.

Coronary artery bypass graft: why is the saphenous vein prone to intimal hyperplasia?

Proliferation and migration of smooth muscle cells and the resultant intimal hyperplasia cause coronary artery bypass graft failure. Both internal mammary artery and saphenous vein are the most commonly used bypass conduits. Although an internal mammary artery graft is immune to restenosis, a saphenous vein graft is prone to develop restenosis. We found significantly higher activity of phosphatase and tensin homolog (PTEN) in the smooth muscle cells of the internal mammary artery than in the saphenous vein. In this article, we critically review the pathophysiology of vein-graft failure with detailed discussion of the involvement of various factors, including PTEN, matrix metalloproteinases, and tissue inhibitor of metalloproteinases, in uncontrolled proliferation and migration of smooth muscle cells towards the lumen, and invasion of the graft conduit. We identified potential target sites that could be useful in preventing and (or) reversing unwanted consequences following coronary artery bypass graft using saphenous vein.

Vein graft failure: current clinical practice and potential for gene therapeutics

Autologous saphenous vein is commonly used as a conduit to bypass atherosclerotic lesions in coronary and femoral arteries. Despite the wide use of arterial conduits, which are less susceptible to complications and failure, as alternative conduits, the saphenous vein will continue to be used in coronary artery bypass grafting until acceptable alternative approaches are evaluated. Hence, preservation of vein graft patency is essential for the long-term success. Gene therapy is attractive in this setting as an ex-vivo technology to genetically manipulate the conduit before grafting. The use of safe and efficient vectors for delivery is a necessity as well as a strategy to improve patency in the long term. Here, we review the current clinical practice, the pathogenesis of bypass graft failure and adenovirus-mediated gene therapy strategies designed to improve late vein graft failure by modulation of smooth muscle cells in the vein wall.

Pathogenic mechanisms in varicose vein disease: the role of hypoxia and inflammation

AIMS

Although the aetiology of varicose veins remains unknown, recent studies have focused on endothelial cell integrity and function. Among the regulatory factors of vessel tone, synthesises, pro- and anti-inflammatory, adhesion molecules and the transcription factor hypoxia inducible factor-1 alpha (HIF-1alpha), which are responsible for recruiting leukocytes, are very important.

METHODS

Investigation in this study focused on the expression of ICAM-1, E-selectin and HIF-1alpha on endothelial cells using immunostaining and RT-PCR in varicose vein specimens compared with controls.

RESULTS

Findings of this study showed alterations of the intima, such as focal intimal discontinuity and denudation of endothelium in varicose veins. Based on data derived from immunostaining and RT-PCR, no major differences were identified between ICAM-1 and E-selectin expression in varicose vein specimens compared with controls. In contrast, immunostaining results identified HIF-1alpha expression in five (5/20) varicose vein specimens, whereas no control saphenous vein specimens expressed HIF-1alpha.

CONCLUSIONS

These findings could explain other evidence of hypoxia in varicose veins. Finally, results already obtained in this investigation suggest that the process of pathogenesis of varicose veins is not restricted to the role of adhesion molecules.

Inhibition of neointimal formation and hyperplasia in vein grafts by external stent/sheath

Synthetic and to a lesser extent vein graft failure is still a major problem in the treatment of peripheral arterial disease, with neointimal hyperplasia being the main cause for graft occlusion in the medium and long term. This review aims to establish the current status of external stents or sheaths in the prevention of intimal hyperplasia in small diameter (< 6 mm) vein grafts.

Low wall shear stress predicts subsequent development of wall hypertrophy in lower limb bypass grafts

Background

Venous grafts commonly develop myointimal hyperplasia, which can lead to stenoses and, ultimately, with expression of adhesion molecules, lumenal occlusion. The aim of the present study was to investigate whether wall shear stress measured post-operatively would predict subsequent myointimal hypertrophy in lower limb venous bypass grafts.

Methods

Magnetic resonance imaging and ultrasound were performed in a cohort of patients following lower limb venous bypass graft surgery for peripheral arterial disease at baseline (1-2 weeks) and at follow-up (9-12 months). Wall shear stress was determined at baseline using computational fluid dynamics techniques and intima-media thickness along the length of the graft was measured by ultrasound at baseline and follow up.

Results

Complete follow-up was possible in eight patients, in whom low wall shear stress at baseline predicted high intima-media thickness. The relationship between wall shear stress (WSS) and intima-media thickness (IMT) was curvilinear with IMT increasing sharply at lower levels of WSS (IMT >1.0 mm at <0.3 Pa).

Conclusions

Low wall shear stress is associated with subsequent increase in myointimal thickness in lower limb venous bypass grafts. This is believed to be the first prospective study in humans to demonstrate the relationship between low wall shear stress and myointimal thickening and indicates a likely causative role for low wall shear stress in the development of myointimal hyperplasia.

Inhibition of adhesion molecule expression on human venous endothelial cells by non-viral siRNA transfection

Objective: Expression of adhesion molecule receptors on venous endothelial cells crucially influences the fate of venous grafts by mediating leukocyte-endothelium interactions. These interactions include adhesion of leukocytes to the endothelium, followed by transendothelial migration, leading to neointimal hyperplasia and finally graft occlusion. Therefore, inhibition of adhesion molecule expression may be a promising strategy to improve the quality of venous grafts. We tested the efficiency of non-viral transfection of human venous endothelial cells with short interfering RNA (siRNA) to specificially down-regulate adhesion molecule expression. Methods: Primary cultures of human venous endothelial cells (HVEC) were examined for expression of the adhesion molecules ICAM1, VCAM1 and E-selectin (SELE) after non viral siRNA transfection. Adhesion molecule expression was measured by flow cytometry, real-time PCR and immunoblotting after stimulation with TNF-alpha, an inflammatory cytokine. Results: Non-transfected cells showed a strong increase of adhesion molecule expression following cytokine stimulation (p<0.01). Upon transfection with specific siRNAs a six fold decrease in ICAM1 (p<0.001) and SELE expression and cell positivity (p<0.05) and a twofold decrease in VCAM1 expression and cell positivity (p<0.01) could be observed. SiRNA-mediated gene suppression of adhesion molecules was also reflected by corresponding decreases in adhesion protein and transcript levels. Conclusions: The expression of adhesion molecules on HVECs can be effectively inhibited by specific siRNAs using a safe, non-viral transfection approach. This is a promising tool to precondition venous bypass grafts in order to interfere with endothelium-leukocyte interactions and to prohibit neointima thickening or atherosclerosis, which are regarded to be the most important causes of venous graft failure.

Suppressive effect of short-interfering RNA on hyperglycemia-induced expression of intercellular adhesion molecule-1 on cultured vascular endothelial cells

PURPOSE

The pathology of diabetic retinopathy involves endothelial dysfunction, in which leukocyte adhesion to the vascular endothelium via intercellular adhesion molecule-1 (ICAM-1) may play a key role. Short-interfering RNAs (siRNAs) are unique modulators of gene expression in mammalian cells. The purpose of this study was to evaluate the enhanced effect of hyperglycemia and the attenuating effect of siRNAs on ICAM-1 expression in cultured endothelial cells.

METHODS

Human umbilical vein endothelial cells (HUVECs) were seeded onto 24-well culture plates. The following day, ICAM-1-specific siRNAs were transfected using Lipofectamine 2000. Glucose (15, 30, or 45 mM) or interleukin-1ss as a positive control was added to the medium to stimulate ICAM-1. After 48 hours, the HUVECs were collected to measure the ICAM-1 expression by enzyme-linked immunosolvent assay. Fluoresceinated siRNAs were transfected into HUVECs to confirm transfection of the siRNAs into HUVECs by fluorescein microscopy.

RESULTS

Glucose enhanced the ICAM-1 expression in a dose-dependent manner. ICAM-1 expression stimulated by hyperglycemia decreased significantly in the HUVECs transfected with corresponding siRNAs. Transfection of siRNAs was confirmed with enhanced fluorescence in HUVECs incubated with control siRNAs.

CONCLUSIONS

These results suggested that hyperglycemia stimulated protein expression of ICAM-1 and that siRNAs suppressed gene expression of ICAM-1 in HUVECs. The RNA-targeting approach using siRNAs may provide a novel therapeutic option for diabetic retinopathy.

Inhibition of adhesion molecule expression on human venous endothelial cells by non-viral siRNA transfection

Objective:

Expression of adhesion molecule receptors on venous endothelial cells crucially influences the fate of venous grafts by mediating leukocyte-endothelium interactions. These interactions include adhesion of leuko-cytes to the endothelium, followed by transendothelial migration, leading to neointimal hyperplasia (NIH) and finally graft occlusion. Therefore, inhibition of adhesion molecule expression may be a promising strategy to improve the quality of venous grafts.We tested the efficiency of non-viral transfection of human venous endothe-lial cells (HVEC) with short interfering RNA (siRNA) to specifically down-regulate adhesion molecule expression.

Methods:

Primary cultures of HVEC were examined for expression of the adhesion molecules ICAM1, VCAM1 and E-selectin (SELE) after non viral siRNA transfection. Adhesion molecule expression was measured by flow cytom-etry, real-time polymerase chain reaction and immunoblotting after stimulation with TNF-α, an inflammatory cytokine.

Results:

Non-transfected cells showed a strong increase of adhesion molecule expression following cytokine stimulation (P < 0.01). Upon transfection with specific siRNAs a sixfold decrease in ICAM1 (P < 0.001) and SELE expression and cell positivity (P < 0.05) and a twofold decrease in VCAM1 expression and cell positiv-ity (P < 0.01) Pcould be observed. SiRNA-mediated gene suppression of adhesion molecules was also reflected by corresponding decreases in adhesion protein and transcript levels.

Conclusions:

The expression of adhesion molecules on HVECs can be effectively inhibited by specific siRNAs using a safe, non-viral transfection approach. This is a promising tool to pre-condition venous bypass grafts in order to interfere with endothelium-leukocyte interactions and to prohibit neointima thickening or ath-erosclerosis, which are regarded to be the most important causes of venous graft failure.

Architectonic arrangement of the vasa vasorum of the human great saphenous vein

OBJECTIVE

The detailed spatial arrangement of the vasa vasorum (VV) of the human great saphenous vein (HGSV) was demonstrated in qualitative and quantitative terms.

MATERIALS AND METHODS

Segments of the HGSV taken from cadavers 12-24 h post mortem and from patients undergoing aortocoronary bypassing were studied by light microscopy of India-ink-injected specimens and by scanning electron microscopy of vascular corrosion casts.

RESULTS

Arterial feeders were found to approach the HGSV from nearby arteries every 15 mm forming a rich capillary network within the adventitia and the outer two thirds of the media in normal HGSV, while in HGSV with intimal hyperplasia capillary meshes extended into the inner layers of the media. Within the media, capillary meshes ran circularly. Postcapillary venules drained centrifugally towards the adventitial venous vessels which finally formed venous drainers running adjacent to the arterial feeders. Three-dimensional morphometry of vascular corrosion casts of VV revealed that diameters of (i) arterial VV ranged from 11.6 to 36.6 microm, (ii) capillary VV from 4.7 to 11.6 microm and (iii) venous VV ranged from 11.6 to 200.3 microm.

CONCLUSIONS

The 3D network of VV suggests these layers are metabolically highly active and therefore require a continuous blood supply. We conclude, therefore, that the VV network must be preserved during in situ bypassing.

On the biology of saphenous vein grafts fitted with external synthetic sheaths and stents

Autologous saphenous vein is used as a conduit to bypass atherosclerotic lesions in both the coronary artery (coronary artery bypass graft surgery [CABG]) and in femoral arteries (infrainguinal bypass graft surgery [IIBS]). Despite the undoubted success and benefits of the procedures, graft failure occurs in 50% of cases within 10 years after surgery. A principal cause of late vein graft failure is intimal and medial hyperplasia and superimposed atherogenesis. Apart from lipid lowering therapy, no intervention has hitherto proved clinically effective in preventing late vein graft failure which clearly constitutes a major clinical and economic problem that needs to be urgently resolved. However, we have studied the effect of external synthetic stents and sheaths in pig models of vein into artery interposition grafting and found them to have a profound effect on vein graft remodelling and thickening. In this review, therefore, we will summarise the mechanisms underlying vein graft failure and how these stents influence these processes and the possible mechanisms involved as well as the application of these devices in preventing vein graft failure clinically.

Neutrophil adherence to activated saphenous vein and mammary endothelium after graft preparation

BACKGROUND

Interaction of circulating leukocytes and vascular endothelium plays an important role in vasoconstriction, endothelial dysfunction, and vascular injury. Dilation procedures of grafts before coronary artery bypass graft surgery might lead to vascular injury and subsequent bypass graft disease.

METHODS

We analyzed in vitro the adherence of fluorescence-labeled polymorphonuclear neutrophils (PMNs) to endothelium of human saphenous vein grafts or internal mammary artery grafts after stimulation with thrombin (0.5 to 2 U/mL) or dilating procedures. Furthermore, we investigated endothelial function of prepared grafts.

RESULTS

Thrombin stimulation resulted in a dose-dependent increase of PMN adherence to the endothelium of saphenous vein and internal mammary artery, which was attenuated by the selectin-blocking carbohydrate fucoidin or anti-P-selectin monoclonal antibody. Mechanical dilation of saphenous vein or internal mammary artery led to a marked increase in PMN adherence (65 +/- 5 versus 5 +/- 3 PMN/mm2; p < 0.01), which was significantly attenuated by fucoidin or anti-P-selectin monoclonal antibodies. Treatment of internal mammary artery with the vasodilator papaverine led to a marked increase of PMN adherence (59 +/- 8 versus 12 +/- 4 PMN/mm2; p < 0.01) when papaverine was administered directly into the vessel. However, external treatment with papaverine did not affect PMN adhesion. Endothelial dysfunction was observed in dilated venous grafts and in arterial grafts internally treated with papaverine; in contrast, external treatment did not affect endothelial function.

CONCLUSIONS

This study showed that mechanical or pharmacologic dilation of venous or arterial coronary grafts, usually performed before anastomosis of aortocoronary bypass grafts, led to increased selectin-mediated PMN adhesion on vascular endothelium and subsequent endothelial dysfunction.

Endoscopic versus conventional radial artery harvest for coronary artery bypass grafting: functional and histologic assessment of the conduit

BACKGROUND

The radial artery's propensity for vasospasm and vulnerability to surgical trauma are well known. A less invasive endoscopic method to harvest the radial artery was recently introduced, but its effect on radial artery integrity is unknown.

METHODS

To compare the effects of harvest method on radial artery function, we prospectively randomized 54 patients undergoing coronary artery bypass grafting with the radial artery into 3 groups on the basis of harvest techniques: endoscopic, conventional with cautery, and conventional with harmonic scalpel. We assessed endothelium-dependent and endothelium-independent relaxation of radial artery segments to sequential doses of acetylcholine and nitroglycerin, respectively, using standard organ-chamber methodology. Vasospasm was assessed as the vasoconstrictor response to the thromboxane analog U46619. We assessed endothelial integrity using light and electron microscopy and by rating intercellular adhesion molecule 1, vascular cell adhesion molecule 1, and P-selectin expression by means of immunohistochemistry on a semiquantitative 0- to 3-point scale. Harvest procedures were performed by a single surgeon, and data analyses were blinded to the harvesting method.

RESULTS

Maximal relaxation-contraction responses to acetylcholine, nitroglycerin, and U46619 and effective drug concentration yielding 50% response were similar in the 3 groups. Adhesion molecule expression and histologic changes, as assessed by means of light and electron microscopy, were similar in the 3 groups.

CONCLUSIONS

Endoscopic harvest does not alter radial artery vasoreactivity or endothelial integrity compared with conventional harvest techniques. Because the endoscopic technique is less invasive, it might prove to be the technique of choice to harvest the radial artery.

Effects of Resveratrol in Storage Solution on Adhesion Molecule Expression and Nitric Oxide Synthesis in Vein Grafts

BACKGROUND

Endothelial injury in human saphenous vein grafts may occur during harvesting and storage, which may have an adverse effect on coronary artery bypass grafting outcome. In this study, we sought to determine whether resveratrol, a natural antioxidant enriched in grape, can limit endothelial activation and reduce endothelial injury in human saphenous vein grafts.

METHODS

Human saphenous vein grafts, obtained from 8 patients and divided into two equal groups of control and study specimens, were stored in either heparinized blood (group A) or heparinized blood containing 50 microg/mL resveratrol (group B) for 1 hour at room temperature. Specimens were analyzed by Western blotting to quantify intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and inducible nitric oxide synthase-2 expression, as well as tissue cyclic guanylate monophosphate levels. Myeloperoxidase activity, a marker of neutrophil sequestration in human saphenous vein grafts, was also measured in each group.

RESULTS

Intercellular adhesion molecule-1 expression (1,674 +/- 332 versus 559 +/- 282; p = 0.003), vascular cell adhesion molecule-1 expression (753 +/- 183 versus 472 +/- 151; p = 0.025), and myeloperoxidase activity (7.00 +/- 1.05 versus 1.33 +/- 0.45 nm/min; p = 0.004) were significantly lower in group B. In contrast, inducible nitric oxide synthase-2 expression (548 +/- 237 versus 2,234 +/- 726; p = 0.004) and tissue cyclic guanylate monophosphate levels (2.02 +/- 0.53 versus 5.61 +/- 0.89 pmol/mL; p = 0.001) were significantly higher in group B.

CONCLUSIONS

Resveratrol reduced upregulation of leukocyte-endothelial cell adhesion molecule expression in human saphenous vein graft endothelium and decreased neutrophil adhesion to saphenous vein graft endothelium. Resveratrol also augmented inducible nitric oxide synthase-2 expression and increased cyclic guanylate monophosphate levels. These results suggest that resveratrol might improve vascular homeostasis and reduce endothelial injury during the hypoxic storage period of human saphenous vein grafts for coronary artery bypass grafting.

Evaluation of serum levels of solubilized adhesion molecules in patients with aortocoronary saphenous vein grafts

OBJECTIVE

To assess the diagnostic importance of serum-solubilized adhesion molecules, vascular cell adhesion molecule-1, intercellular adhesion molecule-1, sE-selectin and sP-selectin in aortocoronary saphenous vein graft disease.

METHODS

The study population was composed of two groups consisting of 41 patients with saphenous vein graft stenosis (stenosis group) and 43 patients without saphenous vein graft stenosis (no-stenosis group) based on the results of coronary angiography. All patients underwent coronary artery bypass graft operation involving the use of at least one saphenous vein graft for bypass. At the time of cardiac catheterization, it had been more than 1 year since the operation.

RESULTS

Serum level of sP-selectin was significantly higher in the stenosis group than in the no-stenosis group (72.9+/-21.7 versus 48.7+/-18.6 ng/ml, P<0.001). No differences were found between the two groups with respect to serum levels of sE-selectin, intercellular adhesion molecule-1 and vascular cell adhesion molecule-1. Multivariate analysis revealed that only serum levels of sP-selectin, high-density lipoprotein cholesterol and low-density lipoprotein cholesterol were independently correlated with the stenosis of saphenous vein grafts. A cutoff value of serum sP-selectin >57.5 ng/ml yields a specificity of 79.5%, a sensitivity of 73.3% and a positive predictive value of 80.5% for saphenous vein graft stenosis.

CONCLUSION

In this study, sP-selectin level was found to be significantly higher in the group that had late aortocoronary saphenous vein bypass graft disease. This result suggests that platelet activation may play a causal role in late graft disease.

Immunocytochemical characterisation of the inflammatory cell infiltrate of varicose veins

OBJECTIVES

To characterise the inflammatory cell infiltrate in varicose vein wall, and its relationship to the valve complex.

DESIGN

A comparative study of the distribution of inflammatory cells in normal and varicose vein.

MATERIALS

Specimens of proximal human long saphenous vein were obtained from patients with duplex Doppler confirmed long saphenous vein reflux (n=14). Control vein was obtained from patients undergoing coronary artery bypass without clinical evidence of venous insufficiency (n=6). Longitudinal 7 microm frozen sections of vein, displaying valve, were prepared.

METHODS

Using immunohistochemistry, T-lymphocytes (CD3), macrophage/monocytes (CD68), neutrophils (CD15s) and mast cells (anti-mast cell tryptase) were identified. The number of cells per unit length vein were counted using light microscopy.

RESULTS

There were significantly more mast cells and macrophage/monocytes in varicose vein as compared to control. There was a non-significant trend towards more T-lymphocytes in varicose vein. Few neutrophils were present in varicose or normal vein. The distribution of inflammatory cells with respect to the valve was not found to be significant.

CONCLUSIONS

Varicose veins display a greater inflammatory cell infiltrate than normal vein. The key role of macrophage/monocytes and mast cells in tissue damage and remodelling should stimulate further research into whether they play a significant role in the development of chronic venous insufficiency.

Statin therapy is associated with improved patency of autogenous infrainguinal bypass grafts

OBJECTIVE

HMG-CoA reductase inhibitors (statins) broadly reduce cardiovascular events, effects that are only partly related to cholesterol lowering. Recent studies suggest important anti-inflammatory and antiproliferative properties of these drugs. The purpose of this study was to determine the influence of statin therapy on graft patency after autogenous infrainguinal arterial reconstructions.

METHODS

A retrospective analysis of consecutive patients (1999-2001) who underwent primary autogenous infrainguinal reconstructions with a single segment of greater saphenous vein was performed. Patients were categorized according to concurrent use of a statin. Graft lesions (identified by duplex surveillance) and interventions were tabulated. Comparisons between groups were made by using the Fisher exact test for categorical variables and the Student t test for continuous variables. Patency, limb salvage, and survival were compared by log rank test. A stepwise Cox proportional hazards analysis was then employed to ascertain the relative importance of factors influencing graft patency.

RESULTS

A total of 172 patients underwent 189 primary autogenous infrainguinal arterial reconstructions (94 statin, 95 control) during the study period. The groups were well matched for age, indication, and atherosclerotic risk factors. Procedures were performed primarily for limb salvage (92%), with 65% to an infrapopliteal target. Perioperative mortality (2.6%) and major morbidity (3.2%) were not different between groups. There was no difference in primary patency (74% +/- 5% vs 69% +/- 6%; P =.25), limb salvage (92% +/- 3% vs 90% +/- 4%; P =.37), or survival (69% +/- 5% vs 63% +/- 5%; P =.20) at 2 years. However, patients on statins had higher primary-revised (94% +/- 2% vs 83% +/- 5%; P <.02) and secondary (97% +/- 2% vs 87% +/- 4%; P <.02) graft patency rates at 2 years. Of all factors studied by univariate analysis, only statin use was associated with improved secondary patency (P =.03) at 2 years. This was confirmed by multivariate analysis. The risk of graft failure was 3.2-fold higher (95% confidence interval, 1.04-10.04) for the control group. Perioperative cholesterol levels (available in 47% of patients) were not statistically different between groups.

CONCLUSIONS

Statin therapy is associated with improved graft patency after infrainguinal bypass grafting with saphenous vein.

Pressure distension stimulates the expression of endothelial adhesion molecules in the human saphenous vein graft

BACKGROUND

Mechanical trauma occurring during saphenous vein graft harvesting plays a major role in graft failure after coronary bypass surgery. There is increasing evidence that neutrophil-endothelial interaction is involved in the pathogenesis of early graft occlusion. This study evaluates the effect of pressure distension on the expression of endothelial adhesion molecules in human saphenous vein.

METHODS

Segments of saphenous vein graft (SVG) were collected from 20 patients undergoing coronary bypass surgery. We evaluated the expression of intercellular adhesion molecule (ICAM-1), vascular cell adhesion molecule (VCAM-1), and P-selectin on SVG endothelium under basal conditions and after pressure distension at 300 mm Hg. In the same experimental setting we also evaluated adhesion of both unstimulated and activated neutrophils to the endothelium of SVG.

RESULTS

Control endothelial cells exhibited only a weak staining for intercellular adhesion molecule (ICAM-1), vascular cell adhesion molecule (VCAM-1), and P-selectin, whereas the levels of adhesion molecules increased significantly in the distended veins. Similarly, significantly greater adhesion of both unstimulated and activated neutrophils was observed in distended veins compared with control veins.

CONCLUSIONS

Pressure distension of SVG before coronary bypass surgery induces upregulation of endothelial adhesion molecules, with subsequent increase in neutrophil adhesion to the endothelium. Neutrophil adhesion to endothelial cells may contribute to early failure of SVG.

Simvastatin attenuates leucocyte-endothelial interactions after coronary revascularisation with cardiopulmonary bypass

OBJECTIVE

To investigate the effects of preoperative simvastatin treatment on leucocyte-endothelial interactions following coronary artery bypass surgery with cardiopulmonary bypass.

DESIGN

Double blind crossover study. Experiments on polymorphonuclear cells (neutrophils) were done at the end of cardiopulmonary bypass and one hour postoperatively. Endothelial P-selectin expression and neutrophil/endothelial adhesion were evaluated under either normoxic or hypoxic conditions.

SETTING

University hospital (tertiary referral centre).

PATIENTS

Three groups of patients undergoing coronary bypass surgery: 20 patients taking simvastatin for cholesterol control, 16 patients not responsive to simvastatin, and 20 controls.

MAIN OUTCOME MEASURES

Expression of neutrophil CD11b and endothelial P-selectin; adhesion of neutrophils to endothelium.

RESULTS

Cardiopulmonary bypass resulted in a significant increase in neutrophil CD11b expression in all groups. Similarly, the exposure of saphenous vein to hypoxia/reoxygenation induced an augmentation of endothelial P-selectin. However, both neutrophil CD11b expression and endothelial P-selectin exocytosis were less in the simvastatin groups than in the controls. Cardiopulmonary bypass and controlled hypoxia/reoxygenation stimulated neutrophil/endothelial adhesion, but the number of adhering cells was less in the simvastatin groups than in the controls, irrespective of the cholesterol concentration. Treatment of endothelial cells with L-NAME completely reversed the effects of simvastatin.

CONCLUSIONS

Pretreatment with simvastatin reduces neutrophil adhesion to the venous endothelium in patients undergoing coronary surgery, irrespective of its efficacy at lowering cholesterol concentration.

Gene therapy for all aspects of vein-graft disease

Gene therapy could improve human saphenous vein (HSV) coronary vein-graft patency by reducing early thrombosis, neointimal hyperplasia and atherosclerosis. Mouse and rabbit models use veins with much thinner walls than pig or HSVs but atherosclerosis can be more easily induced; none of these models shows early thrombosis. Prostacyclin synthase, tissue factor pathway inhibitor, and tissue plasminogen activator might decrease thrombus formation. Tissue inhibitors of metalloproteinases (TIMPs) reduce intimal migration of smooth muscle cells, while TIMP-3 and the p53 tumor suppressor protein promote apoptosis. Prostacyclin synthase and nitric oxide synthase, and cell cycle inhibitors, such as E2F decoy oligonucleotides (D-E2F), reduce neointima formation. This might be enough by itself to decrease later atherosclerosis. Alternatively, direct targeting with nitric oxide synthase, decoy adhesion molecules, or interleukin-10 might be possible.

VCAM-1 expression precedes macrophage infiltration into subendothelium of vein grafts interposed into carotid arteries in hypercholesterolemic rabbits--a potential role in vein graft atherosclerosis

Intimal hyperplasia and atherosclerosis are major causes of late vein graft failure after coronary artery bypass surgery. Hypercholesterolemia appears to be a key risk factor for atherosclerosis in vein grafts as well as in native arteries. We used a rabbit model of interposition jugular vein graft to the carotid artery and compared intimal thickening, macrophage accumulation, and VCAM-1 expression between hypercholesterolemic (H group) and normocholesterolemic (N group) rabbits. Fifty-nine rabbits were divided into H and N groups. Intimal thickening in vein grafts was approximately three times more prominent in the H group than in the N group. Macrophage accumulation progressively increased with time in H group vein grafts, although it was negligible in the N group. In the H group, moreover, macrophages were initially more abundant in deep intima, and subsequently accumulated in subendothelium of the grafted vein. VCAM-1 expression in luminal endothelial cells of the grafted veins was time-dependently increased after the vein graft surgery in both the H and N groups, and was more prominent in the H group. Comparison of the time-courses between macrophage accumulation and VCAM-1 expression revealed that VCAM-1 expression in luminal endothelium preceded subendothelial accumulation of macrophages. VCAM-1 expression and macrophage accumulation may be key factors which regulate progression of vein graft atherosclerosis.

Oxidative Stress and Lipid Retention in Vascular Grafts

Background —Because saphenous vein grafts (SVGs) exhibit greater cellular heterogeneity and worse clinical outcomes than arterial grafts (AGs), we examined oxidative stress and lipid retention in different vascular conduits.

Methods and Results —In a porcine model of graft interposition into carotid artery, superoxide anion (·O 2 − ) was measured at 2 weeks after surgery. SVGs demonstrated increased ·O 2 − production compared with AGs (SOD-inhibitable nitro blue tetrazolium reduction, P <0.01). The NAD(P)H oxidase inhibitor diphenyleneiodonium ( P <0.01) abolished SVG-derived ·O 2 − , whereas the inhibitors of other pro-oxidant enzymes were ineffective. The change in oxidative stress was also reflected by lower activity of the endogenous antioxidant superoxide dismutase in SVGs than in AGs ( P <0.001). SVG remodeling was associated with increased synthesis of sulfated glycosaminoglycans and augmented expression of a core protein, versican. These changes were accompanied by SVGs retaining significantly more 125 I-labeled LDL than AGs ex vivo ( P <0.001). In hyperlipemic animals, lipid accumulation and oxidized epitopes were preferentially noted in the intima of SVGs at 1 month after surgery.

Conclusions —This study demonstrated significant differences in the biology of SVGs and AGs. SVGs exhibited higher oxidative stress, LDL accumulation, and the presence of oxidized epitopes. These findings suggest that proatherogenic changes in SVGs may commence early after surgical revascularization.

Plasma concentration of soluble vascular cell adhesion molecule-1 and subsequent cardiovascular risk

OBJECTIVES

The purpose of this study was to evaluate whether soluble vascular cell adhesion molecule-1 (sVCAM-1) is a marker for increased cardiovascular risk.

BACKGROUND

Soluble forms of cellular adhesion molecules (CAMs) may be useful markers of endothelial activation and local or systemic inflammation. Recent studies indicate that plasma concentration of soluble intercellular adhesion molecule-1 (sICAM-1) is elevated many years before a first myocardial infarction (MI) occurs. However, only a few prospective studies have evaluated whether sVCAM-1 is also a marker for increased cardiovascular risk.

METHODS

Baseline plasma samples were obtained prospectively from 14,916 healthy participants in the Physicians' Health Study. In a nested, case-control study design, the plasma concentration of sVCAM-1 was measured in 474 men with confirmed MI during the nine-year follow-up period, and in an equal number of control subjects who remained free of reported cardiovascular disease and who were matched for age, smoking status and length of follow-up.

RESULTS

No significant difference in the median baseline sVCAM-1 concentration was found between case and control subjects (638 vs. 634 ng/ml; p = NS). Cardiovascular risk was similar between patients with sVCAM-1 levels in the highest quartile and those in the lowest quartile, in both crude (relative risk [RR] 1.28, 95% confidence interval [CI] 0.85 to 1.92) and adjusted (RR 1.17, 95% CI 0.71 to 1.91) matched-pairs analyses.

CONCLUSIONS

In contrast to previous data on sICAM-1, we found no evidence of an association between sVCAM-1 levels and the risk of future MI in a large cohort of apparently healthy men. These data suggest important pathophysiologic differences between sVCAM-1 and sICAM-1 in the genesis of atherothrombosis.

Expression of intercellular adhesion molecules in human saphenous veins: effects of inflammatory cytokines and neointima formation in culture

Atherosclerosis causes occlusions in as many as 50% of human saphenous vein coronary artery bypass grafts. Monocyte infiltration is an early step in saphenous vein-graft atherosclerosis, however, comparatively little is known of its underlying mechanisms. As a first approach, we sought to define the occurrence, location and regulation of leukocyte adhesion molecules in human saphenous vein before and after surgical preparation for grafting, during neointima formation in culture and on stimulation with inflammatory cytokines. We compared the distribution of intercellular adhesion molecule (ICAM-1), vascular cell adhesion molecule (VCAM-1) and platelet endothelial cell adhesion molecule (PECAM-1 or CD-31) in endothelial cells and smooth muscle cells (SMCs), using immunocytochemistry. ICAM-1 was expressed on endothelial cells before culture and on both endothelial cells and medial or neointimal SMCs after culturing vein for 14 days in 30% foetal bovine serum or after culturing for 24 h with TNF-alpha. Relative tissue levels of ICAM-1 measured by Western blotting were significantly elevated by culturing freshly-isolated (0.02+/-0.01 to 0.18+/-0.03) and surgically-prepared (0.02+/-0.01 to 0.14+/-0.03; n=6) veins or following TNF-alpha treatment of surgically-prepared veins (0.04+/-0.01 to 0.32+/-0.11, n=7). VCAM-1 was undetectable before or after culturing but was strongly upregulated on endothelial cells by incubation with the cytokines TNF-alpha, IL-1alpha or interferon-gamma. PECAM-1 was expressed constitutively on endothelial cells. We conclude that human saphenous vein expresses several adhesion molecules capable of mediating monocyte migration. The increased expression of ICAM-1 in SMC after culturing or cytokine treatment and of VCAM-1 in endothelial cells suggests that interactions with beta1 and beta2 integrins are important pathways for stimulated monocyte ingress into human saphenous vein grafts.