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Results for “Microvessels”

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PubMed1994

Expression of galectins on microvessel endothelial cells and their involvement in tumour cell adhesion.

Lactoside-binding lectins (galectins) with molecular weights of about 14.5 kDa (galectin-1) and 29-35 kDa (galectin-3) bind preferentially to polylactosaminoglycan-containing glycoconjugates and have been found on the surface of tumour cells and implicated in cell-cell and cell-extracellular matrix adhesion and metastasis. We have demonstrated by immunoblotting that both galectin-1 and galectin-3 are present in extracts of endothelial cells cultured from bovine aorta, rat lung, mouse lung and mouse brain microvessels, whereas mouse hepatic sinusoidal endothelial cells expressed primarily galectin-1. These galectins were also localized by indirect immunofluorescent labelling on the surface of the different endothelial cells in culture and by immunohistochemical staining in human tissues in vivo. Anti-galectin-1 antibodies inhibited the adhesion of liver-preferring murine RAW117-H10 large-cell lymphoma cells to hepatic sinusoidal endothelial cells or lung microvessel endothelial cells in vitro. The data indicate that galectin-1 is expressed on the extracellular surface of endothelial cells and can mediate in part the adhesion of RAW117-H10 cells to liver microvessel endothelial cells.

Animals↗

PubMed1990

Inflammatory agonists that increase microvascular permeability in vivo stimulate cultured pulmonary microvessel endothelial cell contraction.

Bovine pulmonary microvessel endothelial cells grown on a flexible substrate contract upon the addition of angiotensin II, thrombin, bradykinin, and U44069, a stable analogue of thromboxane A2. All these agents promote inflammation and increase paracellular permeability in vivo or in vitro. The contractile response is mediated by intracellular and extracellular free calcium: the response is inhibited by TMB-8, an intracellular Ca2+ chelator, and EGTA. Contraction is inhibited by trifluoroperazine, a Ca2(+)-calmodulin antagonist, and by ML-7, an inhibitor of myosin light-chain kinase. Preincubation with PMA, a protein kinase C activator, prevents contraction by angiotensin II. The inactive analogue 4-alpha-phorbol 12,13-didecanoate does not inhibit contraction. In contrast cAMP, carbacyclin (a stable PGI2 analogue), and isoproterenol, agonists known to stabilize the microvascular barrier against inflammatory agents, relax pulmonary microvessel EC. This direct evidence of the contractile potential of microvessel endothelial cells lends support to the theory that endothelial contraction leads to increased junctional permeability.

Angiotensin II↗

PubMed1983

Uptake of adenosine by isolated bovine cortex microvessels.

The uptake of adenosine is studied in microvessels isolated from a bovine cortex. The KM value for adenosine uptake is 1.92 microM and the Vmax is 1.93 picomole/mg protein/10 min. This high affinity uptake system is very sensitive to inhibition by dipyridamole and papaverine. The uptake of adenosine by microvessels is also inhibited by CuCl2 and by high concentration (2 mM) of adenine nucleotides. Using a series of four xanthines is observed that the adenosine uptake system is most inhibited by 3-methyl-l-(5'-oxohexyl)-7-propylxanthine and the least by caffeine. Theophylline causes a stimulation of adenosine uptake by microvessels. The results obtained agree with the existence of the nucleoside transport system associated with the blood-brain barrier, as previously observed by in vivo studies and experiments with rat brain capillaries.

Adenosine↗

PubMed1986

On the composition and characteristics of microvessels isolated from the rabbit and bovine brain.

Brain capillaries (microvessels) were isolated from the rabbit and bovine brain. Extensive morphological examinations were performed at the light and electron microscopical levels. The relative contribution of endothelium (52%), basal membrane (32%) and pericytes (16%) to the composition of the microvessel was assessed. The ability of the endothelium from bovine brains to maintain a membrane potential, i.e. to accumulate the lipophilic cation [3H]TPMP, was shown. The transmitter catabolizing enzymes MAO and AchE were shown to be, and COMT and GABA-T not to be associated with the microvessel fraction isolated from rabbits.

4-Aminobutyrate Transaminase↗

PubMed1992

Dietary manipulation with high marine fish oil intake of fatty acid composition and arachidonic acid metabolism in rat cerebral microvessels.

Male weanling Wistar rats were maintained on one of two semisynthetic diets, differing only in the type of oil used: (i) 10% by weight marine fish oil (MFO group) containing 20% eicosapentaenoic acid (EPA) and 17% docosahexaenoic acid (DHA), or (ii) 10% by weight sunflower oil (SFO group). The control group was kept on standard diet for 4 weeks. Blood-free microvessels were isolated from brain cortex by a rapid micromethod, and their fatty acid composition was determined by gas chromatography. It was found that the proportion of n-3 fatty acids (including EPA and DHA) increased significantly in the microvessels of the MFO group, accompanied by a decrease of the n-6 fatty acid series. The changes in fatty acid composition of endothelial cells were not significant in the SFO group in comparison to the control. The amounts of lipoxygenase and cyclooxygenase metabolites were determined. Dietary fish oil decreased the percentage of total products of arachidonate by 50%, while the SFO diet had no effect on it. The amount of lipoxygenase products in the MFO group decreased significantly from 16931 +/- 3131 dpm to 6399 +/- 357 dpm/300 mg wet weight of brain. Significantly less PGF-1 alpha, PGF-2 alpha and 12-hydroxyheptadecatrienoic acid (HHT) were found in the capillaries of MFO treated animals, in comparison to the SFO group. The ratios of vasoconstrictor and vasodilator metabolites of arachidonate cascade were not modified by the diets. Our results suggest that fish oil diet reduces the arachidonate cascade in cerebral microvessels. This effect may explain for the efficiency of n-3 fatty acids in vascular diseases.

6-Ketoprostaglandin F1 alpha↗

PubMed1984

Capacity for energy metabolism in microvessels isolated from rat brain.

Numerous methods used for the isolation of brain microvessels involve procedures which disturb the structural integrity of the cells and their organelles. In the present study, analysis of the adenylate energy charge and content as well as the incorporation of adenosine derivatives in isolated rat brain microvessels indicated a lesion of the mechanisms of energy production. The results show that experiments on isolated microvessels prepared by a mechanical homogenization exerting shear forces should be interpreted with caution when the rate of energy metabolism is a significant factor in the study.

Adenine↗

PubMed1987

Brain 12-HETE formation in different species, brain regions, and in brain microvessels.

We used gas chromatography/mass spectrometry to measure brain 12-HETE (12-Hydroxy-5,8,10,14-eicosatetraenoic acid) formation from endogenous arachidonic acid in different species and different brain regions and in isolated brain microvessels. When blood-free brain slices were incubated for 20 minutes we found that the rabbit and cat brain incubates contained little 12-HETE when compared to rat and mouse brain incubates. Further in vitro studies of various rat brain regions showed a generally even distribution of 12-HETE. When isolated rat or rabbit microvessels were incubated and analyzed, we found 1 and 0.25 micrograms, respectively, of 12-HETE/mg of microvessel protein. Also, rabbit brain had limited or no capacity to actively metabolize tritiated 12-HETE. In summary, these studies show substantial species variation with respect to brain formation of 12-HETE and indicate that the vasculature is a potentially significant contributor to the 12-HETE found in whole brain tissue.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗

PubMed2002

Computerised visualisation from images of blood flow through frog mesenteric microvessels with multiple complexities.

Blood flow through a frog mesenteric microvessel, consisting of one loop and two successive bends, was recorded by a video-microscopic system and analysed by a PC-based image processing system. After preprocessing, these images were analysed by the image velocimetry, axial tomography and image processing procedures. The blood flow in the microvessel had a Reynolds number of 0.033, and the Dean number varied from 0.004 in the loop to 0.007 in the bend, showing an increase in secondary flow in the bend region. These changes led to outward shifts in the peaks of velocity and concentration profiles, with an increase in the thickness of the outer walls (of about three times) compared with that of the inner walls. The mean velocity and mean cellular concentration showed a similar pattern. The variation in the cellular concentration in the microvessel was visualised by concentration contours and grey-scale images of the cellular distribution. At the inner wall of the complex geometry, the velocity reduced to zero, whereas the cellular concentration varied from 2 to 5%. In the high shear stress regions in the complex geometry, the vessel wall thickness was two-three times more than that in low shear stress regions.

Animals↗

PubMed1981

Cerebral microvessels and derived cells in tissue culture: II. Establishment, identification, and preliminary characterization of an endothelial cell line.

An endothelial cell line has been established from a primary culture of cerebral microvessels isolated from Swiss-Webster mice. The microvessels were isolated by a mechanical dispersion and filtration technique. The cells that emerged from these microvessels, maintained in organoid cultures, proliferated and formed plaques of a single or mixed cell type. The endothelial cell line, designated ME-2, was isolated from one such morphologically homogeneous cell plaque, using both cloning ring techniques and C6 glioma-conditioned medium. An endothelial specific antiserum was made in rabbits and was used immunocytochemically to confirm the cell type of origin of the ME-2 cell line. Not only did the cell type specific antiserum react exclusively with endothelial cells in vivo, but in the brain the antiserum localized preferentially to the luminal membrane of the endothelium. The ME-2 endothelial cells have retained several of their unique properties such as cytomorphology, growth characteristics, and cell type specific surface antigens throughout the life of the line (in one case 40 passages before senescence).

Animals↗

PubMed2000

Microvessel count, proliferating cell nuclear antigen and Ki-67 indices in gastric adenocarcinoma.

The aim of the present study was to immunohistochemically investigate the prognostic value of neovascularization (expressed as microvessel count-MVC) and tumor cell proliferation (expressed as PCNA labeling index PLI and Ki-67 labeling index KLI) in gastric adenocarcinoma. Correlations with clinicopathologic features were also evaluated. Tumor specimens from 74 patients diagnosed as gastric adenocarcinoma were included in this study. Formalin fixed, paraffin embedded tissue sections stained immunohistochemically with F-VIII, PC10 and MIB-1 monoclonal antibodies. By ocular grid subdivided into 100 areas, number of microvessels and PC10, MIB-1 positive and negative cells were counted at x400 magnification. Chi-square test, Kaplan-Meier method and cox regression analysis were used for statistical analysis. The results showed that, MVC and PLI had a significant correlation with invasion and lymph node metastasis. The prognosis was significantly worse in patients with high MVC (>14 ) and with high PLI (>49%). However any relationship was not observed between KLI (38%) and clinicopathologic parameters, so KLI failed to predict the prognosis. Cox model showed that, MVC and PLI were independent prognostic variables. Ki-67 labeling index in gastric carcinomas has no prognostic relevance. However, the evaluation of microvessel count and proliferating cell nuclear antigen index in gastric carcinomas could be reliable indicators of prognosis.

Adenocarcinoma↗

PubMed2000

Bone marrow microvessel density is a prognostic factor for survival in patients with multiple myeloma.

The importance of neoangiogenesis for the progressive growth and viability of solid tumors is well established. Recently, there has been growing evidence that angiogenesis might also be important in hematological malignancies, but only few data are available. In this report, we have studied the impact of bone marrow microvessel density and survival in patients with multiple myeloma (MM). Immunohistochemical CD34 stained paraffin-embedded bone marrow biopsies of 44 patients with newly diagnosed MM were studied. Microvessels were counted in 400 x magnification and the mean number of vessels per area in each sample was noted as the microvessel density (MVD). The median MVD was 48 vessels/mm2, the range was 0-125 vessels/mm2. Using a cut-off value of the median MVD in the Kaplan-Meier analysis, the median survival was 22.2 months in the group with the higher MVD and was not reached in the group with the lower MVD (P< 0.01). In a multivariate Cox regression analysis, using previously identified prognostic factors beta2-microglobulin, C-reactive protein (CRP), and age, MVD remained significant as a prognostic factor (P< 0.03).

Adult↗

PubMed2004

Microvessel density, endothelial-cell proliferation and carbonic anhydrase IX expression in haematological malignancies, bone-marrow metastases and monoclonal gammopathy of undetermined significance.

The aim of the study was to compare the angiogenic status, potential qualitative differences in microvessels and carbonic anhydrase IX expression in bone-marrow (BM) metastases and different haematological tumours at time of diagnosis. The microvessel density (MVD), endothelial-cell proliferation (ECP) and carbonic anhydrase IX (CA IX) immunoreactivity were determined on 210 trephine biopsies from 57 patients with multiple myeloma (MM), 13 with acute myeloid leukaemia (AML), 48 with chronic myeloproliferative syndrome (CMPS), 26 with chronic lymphocytic leukaemia (CLL), 25 with epithelial BM metastases, 18 with monoclonal gammopathy of undetermined significance (MGUS) and from a control group composed of 23 patients without haematological neoplasm. There was an increased MVD and ECP in epithelial BM metastases, MM, AML, CMPS and in a part of CLL. While an ECP greater than 0 was detected in 72% of MM, 75% of CMPS and 92% of AML, it was invariably observed (100%) in the BM metastases. The absence of ECP together with a MVD comparable with the control group in our MGUS cases supports the view that MGUS is a pre-angiogenic condition. Qualitative differences in microvessels were associated with growth patterns in MM and CLL and were observed between the different entities of CMPS. In one-third of the epithelial BM metastases, there was a focal CA IX immunoreactivity, which was never observed in the haematological diseases.

Antigens, Neoplasm↗

PubMed2004

Prognostic relevance of tumour-associated macrophages and von Willebrand factor-positive microvessels in colorectal cancer.

Tumour-associated macrophages (TAM) are involved in tumour angiogenesis and anti-tumour immune response. In colorectal cancer (CRC), an association of high microvascular density (MVD) and unfavourable prognosis has been reported by some investigators. However, heterogeneous patient groups were studied. We, therefore, analysed the correlation between TAM and MVD and the prognostic relevance of MVD, TAM and T lymphocyte infiltration for long-term survival in a homogeneous group of 70 patients with moderately differentiated cancers of the International Union Against Cancer (UICC) stages II and III, who did not receive chemotherapy. MVD was evaluated using immunohistochemistry with antibodies against CD34 and von Willebrand factor (vWF). TAM and T lymphocytes were visualised with antibodies against CD68 and CD3, respectively. Statistical analysis did not reveal a significant correlation between TAM and T lymphocyte numbers and MVD. Multivariate analysis of immunohistochemical data from all CRC patients and the subgroup of patients with UICC stage-II CRC identified TAM- and vWF-positive microvessel numbers as prognostically relevant markers. Low numbers of TAM- and high numbers of vWF-positive microvessels were associated with an unfavourable prognosis. In conclusion, TAM- and vWF-positive microvessel numbers may serve as independent prognostic markers for patients with UICC stage-II and -III CRC and may help to identify patients with an unfavourable prognosis.

Aged↗

PubMed2004

Part of the multiple myeloma-associated microvessels is functionally connected to the systemic circulation: a study in the murine 5T33MM model.

It is now well established that angiogenesis in multiple myeloma (MM) is associated with poor prognosis. The exact function of the newly formed vessels in MM is, however, a matter of debate. It is believed that, in contrast to solid tumor growth, the bone marrow (BM) is a sufficiently vascularized organ to support expansion of the MM clone with no need for additional blood vessels. From this point of view, it could be that MM-associated angiogenesis is rather an epiphenomenon and that the newly formed microvessels form a chaotic network that does not contribute to the blood flow. We investigated whether these newly formed microvessels in MM are connected to the blood circulation. The intravenously injected ferritin 30 min prior to sacrifice was detected in 100% of the BM vessels of control mice. In MM-bearing mice, the ferritin tracer was found in 31% of the MM-associated vessels, indicating a connection with the peripheral blood circulation in these vessels. We conclude that, comparable to the situation in solid tumors, at least part of the tumor-associated microvessels in MM is functionally connected to the blood circulation and, therefore, can participate in the transport of nutrients and in the dissemination of MM cells.

Animals↗

PubMed2006

Increased density and diameter of lymphatic microvessels correlate with lymph node metastasis in early stage invasive colorectal carcinoma.

To determine whether lymphangiogenesis was associated with the development of colorectal carcinoma and whether the mean maximal diameter of lymphatic microvessels (LMMMD) or lymphatic microvessel density (LMVD) is associated with lymph node metastasis in early stage invasive colorectal carcinoma (T1 carcinoma), we used immunohistochemical staining with podoplanin to measure LMMMD and LMVD in intratumoral (LMMMDit, LMVDit) and peritumoral areas (LMMMDpt, LMVDpt) of T1 carcinomas (n=87). By comparing the LMMMD and LMVD in normal large intestine (n=10), adenoma (n=15), and Tis carcinoma (n=15), we found out that the LMVDpt in T1 carcinoma with lymphatic vessel invasion (LVI) was significantly high (P<0.001), and there was a significant decrease in LMMMDpt in T1 carcinoma (P=0.031). Both LMMMDpt and LMVDpt were significantly increased in the T1 carcinomas, with LVI compared with the T1 carcinomas without LVI (P=0.018, P=0.003). Multivariate analysis revealed that LVI and combined greater LMMMDpt and greater LMVDpt were associated with lymph node metastases (P=0.005, P=0.036). These results indicate that lymphangiogenesis might be induced in the surrounding tumor areas of the T1 colorectal carcinoma with LVI; thus, evaluation of the diameter and density of lymphatic microvessels is important in T1 colorectal carcinoma to predict lymph node metastases.

Adult↗

PubMed2006

PDGF and microvessel wall remodeling in adult rat lung: imaging PDGF-AA and PDGF-Ralpha molecules in progenitor smooth muscle cells developing in experimental pulmonary hypertension.

Smooth muscle cells are mostly absent from the walls of microvessels in the adult lung but develop in large numbers as part of the pathology of human and experimental pulmonary hypertensions (PHs). We have previously shown, in an in vivo model of experimental PH, that mesenchymal (interstitial) fibroblasts and intermediate cells are the progenitors of these cells. Although smooth muscle cell development is a defining pathophysiological feature of human PH, little is known about the angiogenic signaling molecules responsible. Here, we report data for platelet-derived growth factor AA (PDGF-AA) and PDGF-Ralpha, two components of an important signaling pathway for fibroblast and myofibroblast proliferation and migration. Using antibodies linked to protein-A gold and high-resolution imaging techniques, we analyzed the expression of these molecules as smooth muscle cells developed from progenitor cell populations and in endothelial cells of the same microvessels. PDGF-AA was highly expressed by each cell type in control lung. As PH developed, the number of antigenic sites for PDGF-AA decreased with time. PDGF-Ralpha expression levels in the control lung were low, relative to the ligand, and fell in PH. These data show, for the first time, a marked phenotypic shift in expression levels of the PDGF-AA isoform and its receptor tyrosine kinase in the progenitor smooth muscle cells developing in the microvessels of the adult hypertensive lung.

Animals↗

PubMed1996

Culture of endothelial cells from human placental microvessels.

Endothelial cells are known to participate in angiogenesis, adaptation of vascular tonus and maintenance of blood fluidity in the microcirculation. To investigate these functions in the placenta, we devised a method of isolation and culture of endothelial cells from villous microvessels. In primary culture, these intraplacental endothelial cells exhibited many features observed in microvascular endothelium from other organs: spindle-shape, rosette associations, circular arrangements and confluence. In contrast to the confluent endothelial cells derived from the umbilical vein, cells from microvessels did not form a cobblestone network. After trypsin digestion of microvessels, magnetic microbeads coated with S-Endol immunoglobulin, antithrombomodulin and Ulex europaeus-I lectins were tested for sorting endothelial cells. Only the microbeads coated with antithrombomodulin allowed a suitable magnetic cell separation after trypsinization. By contrast, the microbeads coated with each of these antibodies or with lectins attached to confluent cells from the second passage. The microbeads detached from the cells at different rates. Their examination by scanning microscopy indicates that a portion of these microbeads was phagocytosed. Microvascular endothelial cells from the second passage were intensively stained by the anti-von Willebrand reaction and only weakly by the anti-smooth muscle alpha-actin reaction. They incorporated acetylated-low density lipoproteins coupled to a fluorescent probe. The positive reactions against the anti-von Willebrand factor and the uptake of the fluorescent acetylated-low density lipoproteins were modified after eight passages.

Absorption↗

PubMed1999

Microvessel precursor smooth muscle cells express head-inserted smooth muscle myosin heavy chain (SM-B) isoform in hyperoxic pulmonary hypertension.

The present study analyzes smooth muscle myosin heavy chain (SMMHC) expression as lung microvascular precursor smooth muscle cells (PSMCs), cells derived from fibroblasts and intermediate cells (immature SMCs), acquire a smooth muscle phenotype in an in vivo model of pulmonary hypertension (PH). Because of the unique contractile properties of the SMMHC isoform SM-B, we analyzed its expression in the microvessels (<100 micrometers diameter) and in larger vessels (100-700 micrometers) quantitatualy by the labeled [strept]avidin-biotin technique (day 1-28), and related this to cell phenotype by transmission microscopy and protein A-gold labeling (at day 28). Airway SMCs of the normal and hypertensive lung uniformly expressed SM-B whereas vascular SMC expression was heterogeneous. Thus, in some large arteries (and veins) SMCs contained cells expressing SM-B while in others all the cells were immunonegative. Microvascular cells expressing SM-B (arteries and veins) were rare in normal lung and numerous in PH, increasing as wall muscle developed in smaller segments with time. As in large vessels, some microvessels had immunopositive cells and others only negative ones. Ultrastructural analysis confirmed that the SMCs of bronchial vessels, and the septal SMCs adjoining alveolar ducts, contained dense filament arrays decorated with SM-B. While the PSMC processes of the normal lung contained sparse filaments decorated with SM-B, these cells expressed dense filament arrays in PH. Fibroblasts migrating to align around the microvessels also expressed SM-B but in the absence of a filament network. For the first time, we demonstrate in vivo that newly developed microvascular PSMCs express the SMMHC SM-B isoform in PH.

Animals↗