An orthotopic aortic graft mouse model to study the immunopathology of chronic vascular rejection.
Explore the source record for details and available documents.
Animals↗
Biomedical subjects
N Blaes
Publications and source records attributed to N Blaes.
Angiotensin II induces phenotype-dependent apoptosis in vascular smooth muscle cells.
Angiotensin II regulates vascular structure through growth and apoptosis, with implications in pathophysiology. Subtypes of vascular smooth muscle cells with specific morphology, growth, or apoptotic features have been isolated. Here, we investigated the effects of angiotensin II on apoptosis of 2 morphologically different rat aortic smooth muscle cell phenotypes. Spindle and epithelioid cell lines cultured under low serum conditions were stimulated by angiotensin II. Responsiveness was evaluated by calcium signaling. In both phenotypes, an angiotensin II type 1 receptor-mediated transient intracellular calcium peak arose from intracellular pools. However, a sustained nifedipine-sensitive calcium entry occurred specifically in epithelioid cells. Angiotensin II did not impair spindle cell survival, whereas a delayed reduction in cell number occurred in epithelioid cells. Cell death through apoptosis was characterized by cellular and nuclear morphology. Consistently, DNA fragmentation, evaluated by biochemical quantification, nuclei staining, and ladders, and caspase 3-like activity were promoted by angiotensin II in epithelioid cells. Kinetics of annexin V binding showed that apoptosis was a delayed process. Angiotensin II-induced apoptosis of epithelioid cells was prevented by angiotensin II type 1 but not type 2 receptor antagonists and was inhibited by a calcium chelator or calcium antagonist. Conversely, epithelioid cell apoptosis could be induced by a calcium ionophore. Thus, the death signaling promoted by angiotensin II in epithelioid cells involves type 1 receptor-mediated calcium entry. These data suggest that angiotensin II can promote angiotensin II type 1 receptor-mediated apoptosis in vascular smooth muscle cells, depending on their phenotype. This process may play a role in vascular remodeling in cardiovascular diseases.
Angiotensin II↗
Modulation of the proliferation and gene expression of vascular smooth muscle cells induced by lymphocyte culture supernatants(1).
Explore the source record for details and available documents.
Animals↗
[Smooth muscular cells with high alpha-actin level cloned by FGF-2 transfection].
Regulation of proliferation and migration are well known roles of fibroblast growth factor 2 (FGF-2) for arterial smooth muscle cells (SMC). We show here, by sense cDNA transfection that endogenous FGF-2 expression controls alpha-actin level in SMC clones. All the high alpha-actin expressing clones were FGF-2 transfected. Control clones carrying a deleted vector showed a weak expression and an altered actin polymerisation compared to the parental cultures. Among FGF-2 transfected clones, alpha-actin expression was heterogenous with diversely high levels. These observations were obtained using normal rat SMC or SMC from a transformed cell line. They indicate a role for endogenous FGF-2 in arterial SMC differentiation. Our results suggest that FGF-2 might act either by permissing clonal growth of already differentiated cells or by regulating expression or stability of alpha-actin. They open new perspective for gene therapy of the arterial wall.
Actins↗
Oestrogen synthesis, oestrogen metabolism and functional oestrogen receptors in bovine aortic endothelial cells.
In order to investigate the mechanisms by which oestrogenic hormones influence the vascular system, we have studied their metabolism and the functioning of oestrogen receptors in bovine aortic endothelial cells from primo-secondary cultures, a widely studied model of vascular pathophysiology. We have demonstrated the enzymic activity of oestradiol-17 beta-hydroxysteroid dehydrogenase, 17-ketoreductase and aromatase in these cells. Immunocytochemical analyses, using two different monoclonal antibodies that recognize epitopes in the A/B domain of the oestrogen receptor, showed that this molecule has a predominantly cytoplasmic localization even after the addition of oestrogen to the culture medium. We showed that the hormone-receptor complexes were functional by demonstrating their transactivating ability in transfection experiments using the luciferase gene reporter and an oestrogen-responsive element transcriptional enhancer, although the amplitude of the response was in the range of only 140-150%: this was not a consequence of the presence of a specific limiting factor, but instead might be related to the peculiar subcellular localization of the oestrogen receptor.
Animals↗
Estrogen synthesis, estrogen metabolism, and functional estrogen receptors in rat arterial smooth muscle cells in culture.
To investigate the mechanisms by which estrogen hormones influence the vascular system, the metabolism of these hormones and the functionality of estrogen receptors were characterized in rat aortic smooth muscle cells from secondary cultures, a widely studied model of vascular biology. Aromatase, estradiol-17 beta-hydroxysteroid dehydrogenase and 17-ketoreductase enzyme activities were demonstrated in these cells. The presence of functional estrogen receptor could also be demonstrated by estrogen-induced transactivating ability in transfection experiments using the luciferase gene reporter and an estrogen responsive element as transcriptional enhancer although the amplitude of the response was only in the range of 140 to 150%. Immunocytochemical analyses, using monoclonal antibodies that recognize epitopes in the A/B domain of the molecule, showed a predominant cytoplasmic localization of these estrogen receptors, even after estrogen addition to the culture medium. Western blot analysis using antibodies that recognize epitopes in the A/B or F domain gave a mol wt of 67,000. Analysis of the estrogen receptor messenger RNA showed that there was no deletion of the proto-signals for nuclear accumulation. The aromatase and dehydrogenase activity results, coupled with the estrogen receptor immunological, RNA analysis, and transfection data strongly support the contention that rat aortic smooth muscle cells are estrogen target cells. This in vitro model is convenient for studying the mechanisms of action of estrogen hormones that seem very peculiar in this cell population.
17-Hydroxysteroid Dehydrogenases↗
Transformed rat arterial smooth muscle cells induce platelet aggregation.
Atherogenesis is characterized by a proliferation of arterial smooth muscle cells that may be of transformed nature. Platelets are implicated in the progression of atherosclerotic lesions through thrombotic complications. The present study was designed to investigate whether transformed arterial smooth muscle cells (SMC) could specifically aggregate platelets. We used rat transformed arterial SMC lines, V6- and V8-lines, that we had previously established. Experiments were performed with an in vitro homologous rat system. Suspensions of SMC were added without any other aggregating agent to rat heparinized platelet-rich plasma (PRP) in a coagulo-aggregometer. The effect of transformed V6-line and V8-line SMC was compared to that of their normal parental counterparts, V6- and V8-parent cells. Suspensions of transformed SMC induced, in a dose-dependent manner, an immediate and reversible ADP-like platelet aggregation. The amplitude of platelet aggregation was much higher with addition of transformed cells than of the corresponding control SMC (7.39 +/- 0.75 cm vs. 0.85 +/- 0.62 cm with 2 x 10(6) SMC, V6-line vs. V6-parent cells, respectively). ADP-like aggregation did not significantly differ between the two transformed V6- and V8-lines. ADP-like platelet aggregation was also obtained with supernatants of transformed SMC suspensions, the amplitude being higher with supernatants than with cell suspensions (21.0 +/- 3.64 cm vs. 6.8 +/- 1.22 cm with 1.0 x 10(6) V8-line cells, supernatant vs. cell suspension, respectively). The transformed SMC-induced aggregation of platelets was inhibited by apyrase (125 microM) and iodoacetate (25 mM) and thus was ascribable to ADP released by the SMC. In addition, all suspensions of SMC, normal or transformed, but not their supernatants, induced plasma clotting after variable coagulation times. Coagulation was inhibited by hirudin (25 to 100 U/ml) and phospholipase A2 (10 U/ml) indicating thrombin generation through activity of the SMC membrane tissue factor. The present results show that transformed arterial smooth muscle cells may directly aggregate platelets via a release of ADP and this could be of pathophysiological relevance for thrombosis associated with atherosclerosis.
Adenosine Diphosphate↗
Isolation of two morphologically distinct cell lines from rat arterial smooth muscle expressing high tumorigenic potentials.
Smooth muscle cell proliferation is an important feature of atherogenesis. Some works have hypothesized that a transformation of smooth muscle cells could arise during this pathological process. The present paper describes two spontaneously transformed cell lines of arterial smooth muscle cells (SMC) established from aortic media of adult rat. The cell lines have been designated V6 and V8; some of their morphologic, growth, and metabolic characteristics are described and compared to their parent cells. The two cell lines appeared distinct by their morphology and by their degree of transformation. V6 cells appeared as elongated spindle-shaped cells whereas V8 cells were spread cells with a cobblestone pattern. Karyotypes of both cell lines showed a high polyploidy level. V6 and V8 cell lines were immortalized and showed growth characteristics of transformed cells: low requirement of serum to grow, ability to form colonies in soft agar and tumorigenicity in nude mice; V8 cells presented a higher malignancy than V6 cells. Both V6 and V8 cells exhibited characteristics of cultured arterial SMC: ultrastructure, alpha actin expression at the protein and mRNA level, prostacyclin production. The remarkably different morphologies of the V6 and V8 lines and their transformed phenotype suggest that these cell lines could be useful models to study SMC differentiation and proliferation with respect to atherosclerotic or hypertensive vascular diseases.
Actins↗
[Up-date on atherosclerosis].
The major steps of the pathogenesis of atherosclerosis are now well defined. Efforts are still required to better characterize: 1. the cellular mechanisms of atherogenesis, without ignoring the limitations of the available experimental models; 2. the complications of human atherosclerosis, ie the events (ulceration, thrombosis) that provoke ischaemic manifestations. Four short reviews on topics of special interest follow: proliferation of arterial smooth muscle cells; interactions of blood cells (platelets, leukocytes) with the arterial wall; lipoproteins in the genesis of foam cells; recent progresses in genetic epidemiology of cardiovascular diseases.
Animals↗
Nicotine increases basal prostacyclin production and DNA synthesis of human endothelial cells in primary cultures.
In order to better understand the direct effects of nicotine on the metabolism of human vascular endothelial cells we studied the effect of the drug on prostacyclin (PGI2) production and cellular proliferation. This study was performed in an in vitro model of primary cultures of human umbilical vein endothelial cells. PGI2 level was measured with a radioimmunoassay of 6-keto-PGF1 alpha secreted into culture medium. We observed that incubating the cells with nicotine resulted in a dose-dependent increase of the basal level of PGI2; however, at high doses, nicotine, tended to decrease the capacity of production obtained by thrombin stimulation. Endothelial cell growth was stimulated by nicotine with a maximal effect at 0.05 microgram/ml nicotine. We conclude that nicotine appeared, in some experimental conditions, to stimulate some parameters of endothelial cell metabolism and particularly prostacyclin production. Our results stress the importance of the experimental conditions, and may provide an explanation for the disparities of results in the literature. The results are discussed in relation to smoking induced vascular alteration.
Cell Division↗
Decreased prostacyclin production by human umbilical vein endothelial cells cultured with endothelial cell growth factor and heparin.
Explore the source record for details and available documents.
Cell Count↗
[Establishment of a transformed line of arterial smooth muscle cells].
Biology of the vascular cells is widely studied by means of cell culture techniques. In the present work the description of a transformed cell line of arterial smooth muscle cells is presented. The cell line, named V8, has been established from cells of adult rat aortic media. The cells presented proliferation characteristics in vitro, in soft agar, and in vivo in nude mice demonstrating a tumorigenic ability. This cell line provides an interesting model for the study of growth regulation of arterial smooth muscle cells specially in the areas of hypertension and atherosclerosis.
Animals↗
Nicotine alters fibronectin and factor VIII/vWF in human vascular endothelial cells.
Primary cultured human endothelial cells derived from umbilical cord vein were exposed during the growth of the culture to medium containing nicotine at various concentrations (0.5-200 micrograms/ml). Patterns of cellular fibronectin and factor VIII/vWF were compared to control by immunofluorescence technique. The levels of glycoproteins released in the culture medium were quantified by ELISA method. Treated cells showed an important decrease in fibronectin content with fragmentation of the fibronectin pericellular filaments, whereas the levels of secreted fibronectin were reduced in a dose-dependent manner. This reduction of fibronectin availability was correlated with an elongation of cell shape as revealed with phase contrast microscopy. By immunofluorescence, factor VIII/vWF cytoplasmic granules appeared drastically reduced whereas the secretion of the protein was significantly increased. As shown by electron microscopy, there was a concomitant reduction in the number and size of Weibel-Palade bodies. These studies indicate that nicotine modifies fibronectin and factor VIII/vWF distributions but in different ways.
Blood Vessels↗
Actin microfilaments and fibroin secretion in the silkgland cells of Bombyx mori. Effects of cytochalasin B.
Bombyx mori posterior silkgland cells exhibit an impressive microfilament apparatus located at the cellular apex. It consists of bundles of packed, long microfilaments of 50-70 A diameter running along circumferences delimiting the lumen of the gland, perpendicularly to the flow of luminal silk. Microfilaments are closely associated with microtubules of the cytoplasmic 'radial microtubule system'. Immunolabelling with purified antihuman actin antibodies was used to demonstrate their actin-like nature. Apical microfilaments are sensitive to cytochalasin B (CB) which selectively inhibits the secretion of fibroin. Following the removal of the drug, microfilaments recover their normal morphology and secretion resumes. The possible implication of contraction of microfilaments in the process of secretion is discussed.
Actins↗
Growth-stimulating effect of catecholamines on rat aortic smooth muscle cells in culture.
The effect of epinephrine was tested on the proliferation of rat arterial smooth muscle cells (SMC) in secondary cultures. Epinephrine added daily to the culture medium caused a striking stimulation of growth. The effect increased with time and was dose-dependent. Maximal stimulation was observed at a concentration of 10(-5) M and after 72 hours. At higher concentrations (10(-3) M) epinephrine exhibited toxic effects on SMC. When SMC were maintained quiescent by deprivation of serum, the subsequent addition of epinephrine required serum to significantly enhance growth. This growth stimulation increased with serum concentration (from 0.1% to 10%). All the adrenergic agonists tested were found to stimulate SMC growth, with an activity classified by decreasing order as follows: norepinephrine greater than epinephrine greater than isoproterenol. Finally, this mitogenic response of SMC to catecholamines was specific since it could be blocked by adrenergic blocking agents, phentolamine being more efficient than propranolol in that connection. The results suggest that epinephrine and other catecholamines may act as growth factors for aortic SMC, at least in rat, mostly through adrenoreceptors.
Animals↗
Comparative phagocytosis in culture of aortic smooth muscle cells and fibroblasts from rat.
Explore the source record for details and available documents.
Animals↗
Selection of a strain of rats with spontaneous high cholesterolemia.
By means of an inbred selection procedure utilizing positive assortative mating, high (SHC: spontaneous high cholesterolemic) and low (SLC: spontaneous low cholesterolemic) blood cholesterol strains of rats were developed. This procedure was shown to be much more efficient in increasing than in lowering the blood cholesterol level. The diet used throughout selection was normal laboratory chow; therefore the high and low blood cholesterol levels occurred spontaneously. Since the 6th generation there has been no overlap between the blood cholesterol values of the animals of the two strains. The cholesterol increase with ageing was found to be strongly related to sex, but weakly to the genes governing the differences between SHC and SLC rats. Cholesterol enhancement following a hyperlipidic diet did not differ between strains or sexes. It appears that the SHC rat strain could be an interesting model, particularly in pharmacological research.
Aging↗
[Effect of adrenaline on the proliferation of the tunica media smooth muscle cells of rat aorta in culture].
The proliferation of Rat medial aortic smooth muscle cells in secondary cultures is increased with adrenalin. The maximal effect is obtained after 3 days and the increase is dose-dependent. Thus adrenalin might be one of the factors responsible for the proliferation of smooth muscle cells that could play a key role in the formation of the atherosclerotic plaque in vivo.
Animals↗