Inhibition of tissue factor activity reduces the density of cellular network formation in an in vitro model of angiogenesis

2002 ◽  
Vol 30 (1) ◽  
pp. A36-A36
Author(s):  
N. J. James ◽  
C. Ettelaie ◽  
A. O. Oke ◽  
K. R. Bruckdorfer
Keyword(s):  
Tissue Factor ◽  
Cellular Network ◽  
In Vitro Model ◽  
Network Formation ◽  
Factor Activity ◽  
Tissue Factor Activity ◽  
Vitro Model

Inhibition of tissue factor activity reduces the density of cellular network formation in an in vitro model of angiogenesis

2002 ◽  
Vol 30 (2) ◽  
pp. 217-221 ◽  
Author(s):  
N. J. James ◽  
C. Ettelaie ◽  
K. R. Bruckdorfer
Keyword(s):  
Tissue Factor ◽  
Cellular Network ◽  
In Vitro Model ◽  
Network Formation ◽  
Extrinsic Pathway ◽  
Transmembrane Glycoprotein ◽  
Vitro Model ◽  
Vasculogenesis And Angiogenesis

Tissue factor (TF) is a transmembrane glycoprotein that was originally recognized for its ability to initiate the extrinsic pathway of coagulation. More recently, additional functions of TF in cellular signalling have emerged, notably the role of TF in vasculogenesis and angiogenesis. We have described previously the ability of a peptide derived from the apolipoprotein B100 (apoB100) moiety of low-density lipoproteins (KRAD14) to inhibit the procoagulant function of TF. In this study, we demonstrate the ability of the KRAD14 peptide to attenuate the density of cellular network structures of T24 cells grown on specialized matrix (MatrigelTM). In addition, an alternative inhibitor of TF activity, the TF8 5G9 antibody, also reduces the density of cellular network formation. Targeted use of a stable structural equivalent of the KRAD14 peptide may thus prove useful in the prophylactic treatment of diseases whose pathologies feature the formation of neovascular tissue, e.g. tumour growth and metastasis, rupture of atherosclerotic plaques and retinopathy secondary to diabetes.

Hypoxia induces capillary network formation in cultured bovine pulmonary microvessel endothelial cells

1995 ◽  
Vol 268 (5) ◽  
pp. L789-L800 ◽  
Author(s):  
P. G. Phillips ◽  
L. M. Birnby ◽  
A. Narendran
Keyword(s):  
In Vitro Model ◽  
Network Formation ◽  
Collagen Gel ◽  
Coronary Artery Occlusion ◽  
In Vivo Studies ◽  
Hypoxic Exposure ◽  
Vitro Model ◽  
Vessel Networks

The development of new vessels (angiogenesis) is essential to wound healing. The center of a wound space is hypoxic, a condition that has been shown to stimulate angiogenesis in animal models of coronary artery occlusion. Because the mechanisms involved in this complex process are difficult to study in situ, an in vitro model would provide a useful complement to in vivo studies. This laboratory has developed and characterized calf pulmonary microvessel endothelial cell (PMVEC) cultures and an in vitro model system of angiogenesis using collagen three-dimensional gels that permit migration of cells into vessel networks. This system was used to study the direct effect of normoxia (20% O2) or hypoxia (5% O2) on PMVEC ability to undergo angiogenesis in vitro. Major changes leading to formation of capillary-like networks occurred during the first 3 days of hypoxic exposure only and included restructuring of actin filament networks, focal changes in distribution of basic fibroblast growth factor, and orientation and migration of cell tracts into a collagen gel matrix to form vessel networks.

An in-Vitro Model Using Thromboelastography to Evaluate the Effects of Anticoagulants On Clot Formation in Plasma Enriched with Autologous Platelets

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 1091-1091
Author(s):  
Jorell Gantioqui ◽  
Ivan Stevic ◽  
Paul Y. Kim ◽  
Keith K. Lau ◽  
Anthony K.C. Chan ◽  
...  
Keyword(s):  
Platelet Count ◽  
Tissue Factor ◽  
In Vitro Model ◽  
Clot Formation ◽  
Clotting Time ◽  
Platelet Counts ◽  
New Anticoagulants ◽  
Safety Margins ◽  
Vitro Model

Abstract Abstract 1091 Background: In the presence of thrombocytopenia, antithrombotic therapy in patients with thrombosis is a challenge for the managing physicians. Current guidelines are based on anecdotal data and expert opinion. Hereby, we used an in-vitro model with thrombelastography (TEG) to study the interactions of anticoagulants with plasma clotting proteins and varying concentrations of platelets. The objective of this study is to better elucidate the range of platelet concentrations in plasma which will permit clot formation in the presence of anticoagulant. Methods: Fresh human platelet-rich plasma and platelet-poor plasma were obtained from the same donors to produce plasma samples with predefined platelet counts. For each experiment, these samples were incubated with a reaction mixture containing 30 μg/mL corn trypsin inhibitor and one of the following anticoagulants at therapeutic concentrations: heparin (0.3 IU/mL), dalteparin (1.0 IU/mL), fondaparinux (1.25 mg/L), rivaroxaban (150 ng/mL) or dabigatran (180 ng/mL). Clotting was initiated with 10 mM CaCl2 and tissue factor (TF) (Thromborel® S). The amount of tissue factor for each anticoagulant was pre-optimized so that the plasma did not clot in the absence of platelets but the clotting time would return to baseline when platelet count increased to 150 x109/L, corresponding to the expected clinical profile. All parameters for TEG (R,a, MA, TMA) were monitored for 180 min. The area under the curve for each TEG tracing in the first 15 min (AUC15) after clot initiation was estimated as it represents a global measurement of clot strength during its formation. Williams' t-test was used to compare multiple data points with its corresponding baseline control. A p < 0.05 was considered statistically significant. Results: The TF concentration in Thromborel S® was 3140 pM as determined by ELISA. We found that the optimal TF concentrations required for each anticoagulant were 1.2 pM, 0.7 pM, 0.07 pM for heparin, dalteparin, and fondaparinux respectively. No extrinsic tissue factor was required for rivaroxaban and dabigatran. In the presence of an anticoagulant, clot formation was significantly delayed when platelet counts were below 50 x109/L (fig.1). In contrast, when platelet counts were between 50–150 x109/L, there were no significant differences in all TEG parameters. The AUC15 linearly decreased when platelet counts fell below 150 x109/L. In the presence of heparinoids, the overall AUCs are reduced by an average of 6-fold comparing to the controls without anticoagulants (fig.2). In the presence of rivaroxaban or dabigatran the reduction in the overall AUCs was minimal compared to the heparinoids. The slopes of AUC15 against platelet count in the heparinoids were similar, with an average slope of 15. In contrast, the direct factor specific anticoagulants had distinctly different slopes that averaged at 56. Conclusion: Our findings suggest that, in the presence of therapeutic concentration of an anticoagulant, coagulation is delayed when platelet count is below 50 x109/L and clot formation is globally attenuated with lower platelet counts. Due to the fact that the clotting time is significantly prolonged when platelet counts fall below the threshold of 50 x109/L, we recommend withholding or reducing anticoagulants when patients with thrombocytopenia have platelet counts lower than this level. This data is consistent with the current clinical practice in adult population. Furthermore, since rivaroxaban and dabigatran required no extrinsic TF to initiate clot formation in our model, these new anticoagulants may have a wider safety margins for the treatment of thrombosis in thrombocytopenic patients. Yet, without the availability of specific antidote for these new anticoagulants, their use in patients with high bleeding risk warrants further evaluation. Disclosures: No relevant conflicts of interest to declare.

Effects of Anti-Neutrophil Cytoplasm Autoantibodies on Tissue Factor Activity by HL-60 Cells In Vitro

2003 ◽  
Vol 57 (1) ◽  
pp. 68-78 ◽  
Author(s):  
L. F. Flores-Suarez ◽  
R. Nowack ◽  
B. A. Yard ◽  
C.-E. Dempfle ◽  
F. J. Van Der Woude
Keyword(s):  
Tissue Factor ◽  
Factor Activity ◽  
Tissue Factor Activity

Selective Increases of Procoagulant Activity in Rabbit Lymphoid Populations In Vitro Following Stimulation with Endotoxin: Dependence on Anatomic Source

1984 ◽  
Vol 51 (02) ◽  
pp. 228-231 ◽  
Author(s):  
Maria P McGee ◽  
Henry Rothberger ◽  
Tung-Kuang Lee
Keyword(s):  
Lymph Node ◽  
Tissue Factor ◽  
Mononuclear Cells ◽  
Procoagulant Activity ◽  
Mononuclear Leukocytes ◽  
Cell Populations ◽  
Factor Activity ◽  
Tissue Factor Activity

SummaryRabbit mononuclear leukocytes isolated from a variety of anatomic sites were examined for ability to generate procoagulant activity in vitro. Marrow, blood and spleen mononuclear cell populations were found to differ functionally from lymph node, thymus and alveolar populations by having much greater ability to increase in tissue factor activity in response to an endotoxin stimulus. Thus, after incubation in the presence of endotoxin, leukocytes obtained from marrow, blood, and spleen were found to increase in procoagulant activity characterized as tissue factor by 832, 1942 and 12.6 fold, respectively. In contrast, pulmonary alveolar macrophages increased in tissue factor activity only by 2.8 fold, and lymph node and thymus mononuclear cells showed little or no increases. These functional differences, demonstrated by exposing the six cell populations to endotoxin under controlled conditions in vitro, likely explain the similar pattern of anatomic selectivity of leukocyte tissue factor increases reported to occur in vivo during endotoxemia and Shwartzman reactions (1).

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