Fibrinolytic activity of endothelial cells from different venous beds.

BACKGROUND: Little is known about the molecular biology of endothelial cells from different venous vascular beds. As a result, our treatment of deep vein thrombosis and pulmonary artery embolism remain identical. As an initial step in understanding venous thromboembolic disease in the trauma and surgical patients, this study sought to investigate the balance between coagulation and fibrinolysis in the pulmonary and deep venous vascular beds and how trauma might influence this balance. MATERIALS AND METHODS: Confluent human iliac vein endothelial cells (HIVECs) and human pulmonary artery endothelial cells (HPAECs), were cultured in the absence or presence of tumor necrosis factor (TNFα; 10 ng/mL) for 24 h. The expression of mediators of coagulation and fibrinolysis were determined by Western blot analysis, and plasminogen activator activity was determined by a fibrin clot degradation assay. RESULTS: After TNFα stimulation, there was decreased expression of endothelial protein C receptor and thrombomodulin in both HIVECs and HPAECs. TNFα stimulation increased urokinase plasminogen activator expression in both HIVECs and HPAECs. There was an increase in the expression of tissue plasminogen activator and plasminogen activator inhibitor-1 in response to TNFα in HPAECs, but not in HIVECs. There was significantly greater clot degradation in the presence of both the conditioned media and cell extracts from HIVECs, when compared with HPAECs. CONCLUSIONS: HPAECs and HIVECs react differently in terms of fibrinolytic potential when challenged with a cytokine associated with inflammation. These findings suggest that endothelial cells from distinct venous vascular beds may differentially regulate the fibrinolytic pathway.

Divergent effects of zinc depletion in brain vs non-brain endothelial cells.

Dietary zinc deficiency is common in developing as well as developed countries. Endothelial cells (EC) lining the inner surface of peripheral blood vessels are sensitive to zinc deficiency and lose structural integrity when exposed to culture media low in zinc or to zinc chelators. In contrast, we demonstrate here that human brain microvascular EC (HBMEC), which constitute the blood-brain barrier (BBB), resist zinc depletion and respond by enhancing their barrier function. This response was specific for HBMEC and did not occur in non-brain EC, such as human umbilical vein endothelial cells, human aortic endothelial cells, and human iliac vein endothelial cells. Our results suggest the presence of specific mechanisms to counteract zinc deficiency at the BBB, likely involving HBMEC junctional complexes. Understanding the mechanisms involved in this unique response might provide means to modulate the BBB dysfunction associated with neurological disorders such as stroke, multiple sclerosis, and Alzheimer's disease.

Characterization of immortalized human umbilical and iliac vein endothelial cell lines after transfection with SV40 large T-antigen.

Most in vitro studies of human endothelial cells have relied on cells derived from human umbilical veins (HUVEC); however, heterogeneity of primary cultured endothelial cells can make critical interpretation of results difficult. Several endothelial cell lines have been produced to serve as a more constant source of endothelial cells. In this study, we characterized the endothelial cell lines EVLB3 and EVLC2 derived from HUVEC, and EVLK1 and EVLK2 derived from human iliac vein endothelial cells (HIVEC). These cell lines maintained the typical endothelial cell cobblestone morphology and appeared to be growth factor independent. They lost PECAM-1 and von Willebrand factor, GP96 was reduced to the level of vascular smooth muscle cells (SMC), but aSMC-actin was far less than in vascular SMC. Antigen levels of tissue-type plasminogen activator (tPA) and plasminogen activator inhibitor (PAI-1) were comparable with young endothelial cells, and mRNA was present for tPA, PAI-1, tissue factor (TF), tissue factor pathway inhibitor and thrombomodulin. This study revealed that mRNA and protein expression of coagulation and fibrinolytic factors was influenced by the stage of cell confluence. No differences could be detected between the endothelial cell lines derived from HUVEC and HIVEC. These cell lines may be a useful tool for studies on cellular interactions of fibrinolytic components or exploring the regulation of TF expression.

Expression of extracellular matrix genes in adult human dermal microvascular endothelial cells and their regulation by heparin and endothelial cell mitogens.

BACKGROUND: Microvascular alterations are prominent features of systemic sclerosis (SSc) and often precede the appearance of clinically detectable fibrosis. The mechanism leading to selective microvascular injury in SSc is not known; however, microvascular endothelial cell (EC) activation has been demonstrated in SSc skin and is considered to be an early event in the pathogenesis of SSc. EXPERIMENTAL DESIGN: The expression of genes encoding extracellular matrix (ECM) proteins was examined in adult human dermal microvascular EC (HDMVEC), human iliac vein EC (HIVEC), and human umbilical vein EC (HUVEC) using indirect immunofluorescence (IIF) and Northern hybridization analysis. The effects of heparin and the endothelial cell mitogens, endothelial cell growth factor (ECGF) supplement and acidic and basic fibroblast growth factors (aFGF and bFGF), on the expression of ECM genes by these cells were also studied. RESULTS: Abundant transcripts for collagen types I, IV, VI, and fibronectin (FN) and weak expression of the type III collagen gene were detected in HDMVEC cultures in the absence of ECGF and heparin. In contrast, in the presence of these factors, no mRNA for types I, III, and VI collagens and marked down-regulation (more than twofold) of mRNA levels for collagen type IV and FN were observed. These results were confirmed at the protein level by IIF staining. In contrast to HDMVEC, HIVEC and HUVEC did not show expression of genes encoding types I, III, and VI collagens under any culture conditions examined. Next we studied the separate effect of heparin and aFGF or bFGF on the expression of ECM genes in HDMVEC. In contrast to the maximal expression of types I and VI collagens and FN detected in the absence of growth factors, aFGF decreased mRNA levels by 43% for type I collagen, by 52% for type VI collagen, and by 47% for FN. The decreases in mRNA levels caused by bFGF were 37, 41, and 36%, respectively. Heparin alone decreased the mRNA levels for these genes by 60, 77, and 65%, respectively; however, FGF potentiated the negative effect of heparin on ECM gene expression. CONCLUSIONS: These results demonstrate that HDMVEC display a unique pattern of expression of ECM genes that is different from that displayed by EC from medium and large vessels. The data also demonstrate that heparin, ECGF supplement, aFGF, and bFGF regulate ECM gene expression in HDMVEC in vitro and suggest that these growth factors may modulate the expression of matrix genes in vivo. Altered expression of ECM genes by HDMVEC may play an important role in diseases affecting the microvasculature, such as SSc.

Extracellular matrix gene expression by human endothelial and smooth muscle cells.

In this study, the expression of extracellular matrix genes by vascular cells from human iliac blood vessels was characterized on the mRNA steady-state level by slot blot and Northern transfer analyses, as well as by in situ hybridization. Endothelial cells were isolated from adult human iliac arteries and veins, as well as from umbilical veins; smooth muscle cells were isolated from adult human iliac arteries and inferior vena cava. The results show that confluent umbilical vein endothelial cells expressed the genes that encode types I, III, IV and VI collagens, as well as fibronectin and laminin. In contrast, the iliac endothelial cells expressed the genes for types IV and V collagens, fibronectin and laminin; mRNA transcripts for types I, III and VI collagens were not detectable. The smooth muscle cells from iliac arteries or inferior vena cava displayed gene expression for types I, III, IV, V and VI collagens, fibronectin and laminin. The results indicate major differences in gene expression for the various types of collagens by human iliac endothelial and smooth muscle cells. Furthermore, the fetal-derived umbilical endothelial cells displayed differential collagen gene expression from that of adult iliac endothelial cells.