Alterations in c-fos expression, cell proliferation and apoptosis in pressure distended human saphenous vein

[Method of optimal hydraulic dilatation of venous conduits for coronary artery bypass grafting]

Hydraulic dilatation is used in everyday cardiac surgical practice for assessment of leak-proofness and prevention of spasm of autovenous shunts. The classical technique envisages manual high-pressure solution injection, which exerts a negative effect on venous conduits and is one of the causes of incompetence of shunts in the postoperative period. Limiting pressure during hydraulic dilatation is necessary to minimize morphological changes and preserve functional viability of venous conduits. The purpose of the present study was to develop and assess efficacy of a standardized methodology of controlled hydraulic dilatation of venous conduits. We worked out an original technique of controlled hydraulic dilatation of venous conduits under perfusion pressure of artificial circulation. This was followed by assessing morphological changes and functional viability of venous segments after controlled hydraulic dilatation as compared with veins after conventional uncontrolled hydraulic dilatation and the control intact veins. Uncontrolled hydraulic dilatation was accompanied by endothelial damage (p<0.05), multiple conduit wall tears (p<0.05) according to the findings of light microscopy, leading to a significant decrease in the functional vitality of the venous conduit (a decreased reaction to hyperpotassium solution, phenylephrine, acetylcholine and sodium nitroprusside (p<0.05) according to the findings of biophysical examination. Our original technique of controlled hydraulic dilatation of venous conduits under perfusion pressure of artificial circulation made it possible not only to evaluate leak-proofness of the vessel but also to achieve comparable to the control segments parameters of structural integrity of the venous wall and functional viability of the conduit. Thus, using the developed method of controlled hydraulic dilatation makes it possible to minimize morphofunctional alterations in venous conduits, influencing the function of autovenous shunts.

In-vitro study of monocytic THP-1 leukemia cell membrane elasticity with a single-cell microfluidic-assisted optical trapping system

We studied the elastic profile of monocytic THP-1 leukemia cells using a microfluidic-assisted optical trap. A 2-µm fused silica bead was optically trapped to mechanically dent an immobilized single THP-1 monocyte sieved on a 15-µm microfluidic capture chamber. Cells treated with Zeocin and untreated cells underwent RT-qPCR analysis to determine cell apoptosis through gene expression in relation to each cell's deformation profile. Results showed that untreated cells with 43.05 ± 6.68 Pa are more elastic compared to the treated cells with 15.81 ± 2.94 Pa. THP-1 monocyte's elastic modulus is indicative of cell apoptosis shown by upregulated genes after Zeocin treatment. This study clearly showed that the developed technique can be used to distinguish between cells undergoing apoptosis and cells not undergoing apoptosis and which may apply to the study of other cells and other cell states as well.

Elevated c-fos expression is correlated with phenotypic switching of human vascular smooth muscle cells derived from lower limb venous varicosities

BACKGROUND

Lower limb venous varicosities (VVs) are clinically common; however, their molecular underpinnings are far from well elucidated. Previous studies have demonstrated that the phenotypic transition of vascular smooth muscle cells (VSMCs) plays a critical role in VV pathogenesis and that c-fos is upregulated in VSMCs from VVs. The present study investigated the histologic and cytologic changes in VVs and the correlation between c-fos upregulation and VSMC phenotypic switching.

METHODS

Thirty-four patients with VVs (VV group) and 13 patients undergoing coronary artery bypass using autologous great saphenous vein segments (normal vein [NV] group) were enrolled in the present study. The great saphenous veins of both groups were harvested for subsequent experiments. Hematoxylin and eosin staining was performed for vein morphologic analysis. Real-time quantitative polymerase chain reaction, immunohistochemistry, and Western blot assays were used to assess mRNA and protein expression of c-fos, α-smooth muscle actin (α-SMA), and osteopontin (OPN). Simple linear regression was used to evaluate the correlation between c-fos and OPN/α-SMA. Primary VSMCs were isolated from both groups and cultured in vitro. A cell counting kit-8 assay and scratch-wound assay were used to analyze the proliferation and migration abilities of the cells, respectively.

RESULTS

The mean age of the patients in the NV and VV groups was 61.4 ± 3.8 years and 59.5 ± 10.4 years, respectively. The vein cavities of the VV group were dilated, and the arrangement of the cells was disordered. The tunica media of the VV group was thicker than that of the NV group owing to the accumulation and proliferation of VSMCs. Significantly elevated mRNA levels of c-fos and OPN were observed in the VV group compared with the NV group, and a positive correlation was further demonstrated between the mRNA levels of c-fos and OPN/α-SMA (R², 0.5524; P < .001). The VSMCs derived from the VV group were more numerous (as shown by the cell counting kit-8 assay) and had a significantly greater migration speed (as shown by the scratch-wound assay) than those derived from the NV group. Moreover, the protein expression of c-fos was significantly upregulated in VSMCs derived from the VV group, and this change was accompanied by a decrease in α-SMA and an increase in OPN expression.

CONCLUSIONS

Both mRNA and protein expression of c-fos were upregulated in VV specimens, and the phenotypic biomarkers (OPN/α-SMA) were altered concurrently. VSMCs derived from VVs showed increased proliferation and migration abilities. Upregulation of c-fos might play a role in the phenotypic switching of VSMCs and subsequently participate in the pathogenesis of VVs.

CLINICAL RELEVANCE

C-fos is an immediate early gene owing to the transient and rapid change in its expression in response to stimuli. It is involved in the regulation of cell proliferation, cell growth, and cell movement. In the present study, varicose vein specimens showed increased mRNA and protein expression of c-fos, accompanied by altered phenotypic biomarkers. The upregulation of the c-fos gene in smooth muscle cells cultured from varicose vein specimens might be associated with phenotypic switching and functional disturbance. These results could contribute to the exploration of the molecular mechanisms underlying the pathogenesis of varicose veins and the development of new therapeutic strategies.

The Key Role of c-Fos for Immune Regulation and Bacterial Dissemination in Brucella Infected Macrophage

The cellular oncogene c-Fos (c-Fos) is a component of activator protein 1 (AP1), a master transcriptional regulator of cells. The suppression of c-Fos signaling by siRNA treatment resulted in significant induction of TLR4, which subsequently activates p38 and ERK1/2 mitogen-activated protein kinases (MAPKs) and enhances F-actin polymerization, leading to an increase in B. abortus phagocytosis. During B. abortus infection, c-Fos signaling is induced, which activates the downstream innate-immunity signaling cascade for bacterial clearance. The inhibition of c-Fos signaling led to increased production of interleukin 10 (IL-10), which partially suppressed lysosome-mediated killing, resulting in increased survival of B. abortus inside macrophages. We present evidence of the regulatory role played by the c-Fos pathway in proliferation during B. abortus infection; however, this was independent of the anti-Brucella effect of this pathway. Another finding is the essential contribution of c-Fos/TRAIL to infected-cell necrosis, which is a key event in bacterial dissemination. These data provide the mechanism via which c-Fos participates in host defense mechanisms against Brucella infection and in bacterial dissemination by macrophages.

P2X7R antagonism after subfailure overstretch injury of blood vessels reverses vasomotor dysfunction and prevents apoptosis

Human saphenous vein (HSV) is harvested and prepared prior to implantation as an arterial bypass graft. Injury and the response to injury from surgical harvest and preparation trigger cascades of molecular events and contribute to graft remodeling and intimal hyperplasia. Apoptosis is an early response after implantation that contributes the development of neointimal lesions. Here, we showed that surgical harvest and preparation of HSV leads to vasomotor dysfunction, increased apoptosis and downregulation of the phosphorylation of the anti-apoptotic protein, Niban. A model of subfailure overstretch injury in rat aorta (RA) was used to demonstrate impaired vasomotor function, increased extracellular ATP (eATP) release, and increased apoptosis following pathological vascular injury. The subfailure overstretch injury was associated with activation of p38 MAPK stress pathway and decreases in the phosphorylation of the anti-apoptotic protein Niban. Treatment of RA after overstretch injury with antagonists to purinergic P2X7 receptor (P2X7R) antagonists or P2X7R/pannexin (PanX1) complex, but not PanX1 alone, restored vasomotor function. Inhibitors to P2X7R and PanX1 reduced stretch-induced eATP release. P2X7R/PanX1 antagonism led to decrease in p38 MAPK phosphorylation, restoration of Niban phosphorylation and increases in the phosphorylation of the anti-apoptotic protein Akt in RA and reduced TNFα-stimulated caspase 3/7 activity in cultured rat vascular smooth muscle cells. In conclusion, inhibition of P2X7R after overstretch injury restored vasomotor function and inhibited apoptosis. Treatment with P2X7R/PanX1 complex inhibitors after harvest and preparation injury of blood vessels used for bypass conduits may prevent the subsequent response to injury that lead to apoptosis and represents a novel therapeutic approach to prevent graft failure.

Cytotoxicity of probiotics from Philippine commercial dairy products on cancer cells and the effect on expression of cfos and cjun early apoptotic-promoting genes and Interleukin-1 β and Tumor Necrosis Factor-α proinflammatory cytokine genes

This study determined cytotoxicity of probiotic Lactobacillus spp. from Philippine dairy products on cancer cells and normal fibroblasts and their effects on expression of early apoptotic-promoting cfos, cjun and proinflammatory cytokine IL-1β, TNF-α genes. Cultures were from Yakult, Bear Brand Probiotic Drink, Nido3+ Powdered Milk. Filter-sterilized supernatants from cultures of Lactobacillus spp. were evaluated for cytotoxicity to colon cancer cells (HT-29 and HCT116), leukemia cells (THP-1), and normal human dermal fibroblasts (HDFn) using PrestoBlue. Bleomycin was the positive control. Absolute quantification of transcript levels was conducted using qRT-PCR. Cytotoxicity index profiles on HDFn, THP-1 of all probiotic supernatants and negative controls suggest nontoxicity to the cells when compared to bleomycin, whereas all probiotic supernatants were found to be cytotoxic to HT-29 and HCT-116 colon cancer cell lines. Expression of cfos, cjun transcripts was significantly upregulated in HT-29 and HCT116 cells treated with probiotic supernatants compared to untreated baseline levels (P < 0.05). Expression of IL-1β and TNF-α by lipopolysaccharide-treated macrophages was significantly downregulated in cells with probiotic supernatants compared to those exposed to MRS medium (P < 0.05). Results provide strong support for the role of Lactobacillus spp. studied in anticancer therapy and in prevention of inflammation that may act as precursor to carcinogenesis.

The effect of distension pressure on endothelial injury and vasodilatation response in saphenous vein grafts: conversion of a bypass graft to a dead pipe

Introduction

Endothelial damage caused by high pressure applied for spasm relaxation during graft preparation is one of the most plausible theories explaining early graft failure.

Aim of the study

We aimed to demonstrate the extent of endothelial damage in saphenous vein grafts distended to different pressure levels by using immunohistochemical methods and in vitro tissue baths.

Material and methods

Saphenous vein grafts (SVGs) of 25 patients who underwent isolated elective CABG surgery were used in this study. By using a specific mechanism, SVGs were distended to five different pressure levels for two minutes: 0 mmHg, 50 mmHg, 100 mmHg, 200 mmHg, 300 mmHg. In vitro tissue baths and immunohistochemical examinations were performed.

Results

None of the grafts distended to 300 mmHg pressure were functional in the tissue bath system. The relaxation response to carbachol of SVGs distended to 0, 50, 100 and 200 mmHg was 97.87 ± 4.47%, 98.52 ± 3.95%, 93.78 ± 3.64%, and 30.87 ± 4.11%, respectively. There were no statistically significant differences in terms of relaxation responses between samples distended to 0, 50, and 100 mmHg (p = 0.490). The relaxation response of samples distended to 200 mmHg was significantly decreased (p = 0.021). The endothelia of samples distended to 0 mmHg were almost intact in CD31 staining. Endothelial cell loss occurred at all tested distension pressures at different degrees.

Conclusion

In vitro and immunohistochemical studies revealed that distending an SVG used for coronary artery bypass grafting with pressures of 100 mmHg or less results in less endothelial damage and increases graft patency.

'No-touch' saphenous vein harvesting improves graft performance in patients undergoing coronary artery bypass surgery: a journey from bedside to bench

The saphenous vein is the most commonly used conduit in patients undergoing coronary artery bypass surgery yet its patency is inferior to the internal thoracic artery. Vascular damage inflicted to the vein when using conventional harvesting techniques affects its structure. Endothelial denudation is associated with early vein graft failure while damage of the outermost vessel layers has adverse long-term effects on graft performance. While many in vitro and in vivo experimental studies aimed at improving vein graft patency have been performed to date no significant 'bench to bedside' advances have been made. Among experimental strategies employed is the use of pharmacological agents, gene targeting and external stents. A 'no-touch' technique, where the saphenous vein is removed with minimal trauma and normal architecture preserved, produces a superior graft with long term patency comparable to the internal thoracic artery. Interestingly, many experimental studies are aimed at repairing or replacing those regions of the saphenous vein damaged when harvesting conventionally. 'No-touch' harvesting is superior in coronary artery bypass patients with long-term data published 5years ago. Here we describe a 'bedside to bench' situation where the mechanisms underlying the improved performance of 'no touch' saphenous vein grafts in patients have been studied in the laboratory.

9-cis Retinoic acid inhibits cumulus cell apoptosis during the maturation of bovine cumulus-oocyte-complexes

Cumulus cell (CC) apoptosis is inversely correlated with embryonic development in vitro. Therefore, inhibition of CC apoptosis is important for proper embryonic development and quality. Retinoic acids (all-transRA and 9-cisRA) are natural components of retinoids, and 9-cisRA is the physiologically active metabolite of retinoic acid in vitro. During in vitro maturation, 9-cisRA enhances oocyte competence through multiple mechanisms affecting the oocyte and preimplantation embryo; however, the effect of 9-cisRA on CC apoptosis has yet to be elucidated. The aim of the present study was to evaluate the effect of 9-cisRA on CC apoptosis and to identify the molecular mechanism underlying that effect. Bovine slaughterhouse cumulus-oocyte complexes (COC) were matured in vitro in the absence or presence of 5 nM 9-cisRA. Cumulus cells were collected from immature and matured COC for the detection of apoptosis and gene expression analysis. Results showed that 9-cisRA reduced the number of apoptotic CC by about 2.7 fold (P < 0.023), compared with control. However, apoptosis is rare in CC of immature COC (0.01% ± 0.001). Transcripts involved in the caspase cascade were down-regulated upon exposure to 9-cisRA, including tumor necrosis factor alpha (TNF-α, 11.1 fold, P < 0.001), tumor necrosis factor alpha receptor 1 (TNFR1, 2.3 fold, P < 0.01), caspase 9 (CASP9, 2.0 fold, P < 0.031), caspase 8 (CASP8, 2.2 fold, P < 0.012), and caspase 3 (CASP3, 2.1 fold, P < 0.006), while antiapoptotic B-cell lymphoma 2 (BCL2) transcript was increased (3.1 fold, P < 0.004), compared with control. In addition, 9-cisRA inhibited mitogen activated protein kinase mRNA expression in CC, including extracellular signal-regulated kinase 1/2 (ERK1, 2.7 fold, P < 0.02; ERK2, 2.7 fold, P < 0.03), and c-Jun N-terminal kinase (JNK, 1.6 fold, P < 0.044), as well as the activator protein-1 (AP1) family members c-jun (1.6 fold, P < 0.041) and c-fos (2.0 fold, P < 0.06). The transcript abundances of TNF-α, TNFR1, CASP9, CASP8, CASP3, ERK1, ERK1, JNK, and BCL2 were increased, while c-fos and c-jun mRNA expression was decreased in the matured CC. On the basis of the data, we suggest that 9-cisRA inhibits CC apoptosis during in vitro maturation of bovine COC.

Preoperative unstable angina causes venous adaptation to surgical graft injury

Ischemic preconditioning may provide a systemic organ protection, evident as the phenomenon known as remote preconditioning. Unstable angina may be a clinical analogue to ischemic preconditioning. Vein graft harvesting induces inflammation of the graft wall. We hypothesized that preoperative unstable angina preconditions vein grafts and reduces the inflammatory response to graft harvesting. Consecutive patients with stable or unstable angina undergoing open heart surgery (n = 12 in each group) were studied. Saphenous vein biopsies were collected at the start of graft harvesting, and when the last proximal anastomosis to the aorta was finished (average 112 minutes later). Gene expression of inflammatory mediators (tumor necrosis factor alpha, interleukin-1beta (IL-1beta), E-selectin (CD62E), intercellular leukocyte adhesion molecule 1, inducible nitric oxide synthase, endothelin-1) increased after surgical handling (semiquantitative RT-PCR). In vein grafts from unstable patients the increase was attenuated for Il-1beta (p < 0.004) and CD62E (p < 0.001). In stable patients the protein expression of IkappaBalpha and heat shock protein72 was reduced by surgical handling (p < 0.04), but was not influenced in unstable patients (immunoblotting). In vitro relaxation to acetylcholine was enhanced, and contractions to phenylephrine and endothelin-1 were attenuated in veins rings from unstable patients (p < 0.003). In conclusion, surgical handling of vein grafts induces inflammation of the vessel wall. This response was reduced in grafts from patients with unstable angina, indicating a possible systemic preconditioning-like effect of acute coronary syndromes.

Vein Graft Harvesting Induces Inflammation and Impairs Vessel Reactivity

BACKGROUND

Saphenous veins are often used for coronary artery bypass grafting (CABG), but loss of patency is a problem. The surgical procedure may contribute to graft injury. Our aim was to study the impact of surgical handling of saphenous veins on graft inflammation and vascular function.

METHODS

Biopsy samples of saphenous veins were taken from 9 patients undergoing elective CABG at the start of vein harvesting (open technique) and after the last proximal anastomosis was sutured. Messenger RNA was extracted and amplified with semiquantitative reverse transcription polymerase chain reaction. Gene expression of proinflammatory cytokines (tumor necrosis factor-alpha, interleukin-1beta), leukocyte adhesion molecules (E-selectin, intercellular adhesion molecule-1), and vasoactive substances (endothelin-1, inducible and endothelial nitric oxide synthase) was investigated. Translocation of nuclear factor-kappaB (NFkappaB) was evaluated with electrophoretic mobility shift assay. Immunostaining for von Willebrand factor was performed to evaluate loss of endothelium, and in vitro vein reactivity to phenylephrine and endothelin-1 was studied.

RESULTS

Gene expression of cytokines and leukocyte adhesion molecules increased after graft harvesting and storage, whereas vasoactive substances did not change. Nuclear translocation of NFkappaB occurred after surgical handling, concurrent with partial loss of endothelium and impaired contractile function.

CONCLUSIONS

Standard surgical handling of vein grafts induces NFkappaB-driven inflammation in the vessel wall and impairs vascular function. This may potentially contribute to both early and late graft occlusion.

Effect of vein graft harvesting on endothelial nitric oxide synthase and nitric oxide production

BACKGROUND

Although the saphenous vein is the most commonly used conduit for coronary artery bypass surgery occlusion rates are high, with more than 50% grafts failing within 10 years. Nitric oxide, a potent vasodilator, also inhibits platelet aggregation, thrombus formation and vascular smooth muscle cell proliferation, is implicated in various vascular pathologies, including graft failure.

METHODS

Saphenous veins were obtained from patients undergoing bypass surgery harvested by conventional methods and with minimal handling, using a "no-touch" technique. Tissue distribution and protein expression of endothelial nitric oxide synthase was compared using immunohistochemistry and Western blot analysis. Nitric oxide generation was assessed using the citrulline assay.

RESULTS

There was injury to conventional compared with no-touch vein segments, in particular to the lumenal endothelium and tunica adventitia. This injury was accompanied by an absence of endothelial nitric oxide synthase immunostaining at regions of endothelial denudation and damaged adventitial layer of conventional veins and a significant reduction (p < 0.05) in endothelial nitric oxide synthase protein expression. Furthermore, nitric oxide release from conventional tissue extracts was significantly (p < 0.05) lower than no-touch vein segments.

CONCLUSIONS

Our results show that there is a reduction in endothelial nitric oxide synthase and nitric oxide release in saphenous veins harvested by conventional surgical methods compared with those prepared atraumatically. These observations may influence graft performance.

Retinal ganglion cell line apoptosis induced by hydrostatic pressure

Cellular responses to changes in pressure are implicated in numerous disease processes. In glaucoma apoptosis of retinal ganglion cells (RGCs) is associated with elevated intra-ocular pressure, however, the exact cellular mechanisms remain unclear. We have previously shown that pressure can induce apoptosis in B35 and PC12 neuronal cell lines, using an in vitro model for pressure elevation. A novel RGC line allows us to study the effects of pressure on retinal neurons. 'RGC-5' cultures were subjected to elevated ambient hydrostatic pressure conditions in our model. Experimental pressure conditions were 100 mm Hg and 30 mm Hg, representing acute (high) and chronic (lower-pressure) glaucoma, and 15 mm Hg for normal intra-ocular pressure, set above atmospheric pressure for 2 h. Negative controls were treated identically except for the application of pressure, while positive controls were generated by treatment with a known apoptotic stimulus. Apoptosis was determined by a combination of cell morphology and specific TUNEL and Annexin V fluorescent markers. These were assessed simultaneously by laser scanning cytometry (LSC), which also enabled quantitative marker analysis. RGC-5 neurons showed a significantly increased proportion of apoptotic cells compared with controls; maximal at 100 mm Hg, moderate at 30 mm Hg and not statistically significant at 15 mm Hg. This graded response, proportionate to the level of pressure elevation, is representative of the severity of analogous clinical settings (acute, chronic glaucoma and normal). These results complement earlier findings of pressure-induced apoptosis in other neuronal cultures. They suggest the possibility of novel mechanisms of pressure-related mechanotransduction and cell death, relevant to the pathogenesis of diseases such as glaucoma.

Mechanical Stretch Induces Phosphorylation of p38-MAPK and Apoptosis in Human Saphenous Vein

Objective— Failure of saphenous vein grafts remains a major limitation of coronary bypass surgery. The aims of the present study were to determine whether pressure distension of human saphenous vein induces the activation of p38-MAPK and to determine its role in apoptosis.

Methods and Results— Phosphorylated p38 was detected at basal levels in human saphenous vein obtained immediately after harvesting. Distended saphenous vein showed significantly higher levels of phosphorylated p38 compared with control vein ( P <0.01) and nondistended saphenous vein maintained for 3 and 6 hours after harvesting (both P <0.01). Apoptosis in distended and nondistended vein was significantly higher at 24 hours compared with control vein, with distended vein showing increased apoptosis compared with nondistended saphenous vein at all time points investigated ( P <0.001). Immunolocalization showed co-localization of phosphorylated p38 and apoptosis. Inhibition of p38 activity reduced the apoptotic index of cultured vascular smooth muscle cells by 72.1%±1.2% and cultured distended saphenous vein segments by 72.7%±0.9%.

Conclusions— Pressure distension of intact human saphenous vein induces activation of p38, and this is associated with apoptosis. Inhibition of p38 kinase activity in saphenous vein smooth muscle cells and intact vein reduces apoptosis. These findings contribute to our understanding of the mechanisms of saphenous vein graft failure.

Altered expression of vascular endothelial growth factor and its receptors in normal saphenous vein and in arterialized and stenotic vein grafts

BACKGROUND

Myointimal thickening is a major cause saphenous vein graft failure. The prominence of medial and adventitial microvessels in stenotic vein grafts and the known angiogenic effects of vascular endothelial growth factor (VEGF) lead us to investigate the expression of VEGF and its receptors in vein graft arterialization and stenosis.

METHODS

Normal and arterialized vein graft segments were evaluated by reverse transcription-polymerase chain reaction (RT-PCR) for expression of VEGF-R1 (flt), VEGF-R2 (KDR), and neuropilin-1. The cells expressing VEGF, VEGF-R1, VEGF-R2, and neuropilin-1 were identified in normal, stenotic, and arterialized vein graft segments by immunohistochemistry.

RESULTS

Vascular endothelial growth factor, detected in the wall in endothelial cells and adventitial microvessels in normal vein, localized to smooth muscle cells, endothelial cells and adventitial microvessels in arterialized and stenotic vein. VEGF-R1 and VEGF-R2 were expressed infrequently on endothelial cells, macrophages, and smooth muscle cells in arterialized and stenotic vein. Neuropilin-1 was detected in all specimens. RT-PCR demonstrated significantly greater expression of neuropilin-1 in normal vein compared with arterialized vein (P <0.05).

CONCLUSIONS

The differential expression of VEGF and its receptors in normal, arterialized, and stenotic vein grafts suggests that alterations in VEGF/VEGF-R2/neuropilin-1 interactions may be important determinants of the adaptive response of vein grafts to arterialization.

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.