MODULATION OF ANTITHROMBOTIC EFFECTS OF CULTURED HUMAN ENDOTHELIAL CELLS BY INHIBITORS OF CYCLOOXIGENASE OR PHOSPHODIESTERASE

1987 ◽  
Author(s):  
T H Müller ◽  
K Rühr ◽  
H H Callisen ◽  
W G Eisert
Keyword(s):  
Endothelial Cells ◽  
Whole Blood ◽  
Platelet Adhesion ◽  
Thrombus Formation ◽  
Aggregate Size ◽  
Phosphodiesterase Inhibitors ◽  
Human Endothelial Cells ◽  
In Vitro System ◽  
Antithrombotic Effects

Intact endothelial cells are known to form a non-thrombogenic surface and to actively restrict the extent of thrombus formation on denuded vessel walls via such mechanisms as the binding of thrombin and activation of protein C, or the synthesis and release of prostacyclin. In an in vitro system, we have investigated how platelet inhibitors modulate the antithrombotic effects of human endothelial cells. Human endothelial cells isolated from umbilical veins were plated on one half of a subendothelial matrix (SEM) harvested from bovine cornea endothelial cells. The endothelial cells were preincubated with a drug and then exposed to anticoagulated whole blood from human donors in the presence or absence of the same drug and agitated for 15 min. The number and size of platelets interacting with the SEM were quantified by morphometric analysis.In our in vitro system, platelet aggregates on SEM that was partially covered with human endothelial cells were significantly smaller than on uncovered SEM. No difference in platelet adhesion was observed. In the absence of endothelial cells, the cyclooxigenase inhibitors acetylsalicylic acid (ASA) and flurbiprofen strongly reduced the size of aggregates formed on the SEM. Pretreatment of only the endothelial cells with ASA increased the size of the aggregates, while ASA treatment of endothelial cells as well as the whole blood did not reduce the mean aggregate size below that of controls. in contrast, the platelet phosphodiesterase inhibitors AHP 719 and UDCG 212 strongly decreased platelet aggregation without reducing platelet adhesion not only in the absence but also in the presence of endothelial cells pretreated with the inhibitors.Our results demonstrate that this in vitro model of a partially injured vessel wall is well suited to study the effects of endothelial cells on platelet function. Moreover, inhibitors of phosphodiesterase in contrast to ASA have profound antithrombotic effects in this model.

Vascular repair utilising immobilised heparin conjugate for protection against early activation of inflammation and coagulation

2015 ◽  
Vol 113 (06) ◽  
pp. 1312-1322 ◽  
Author(s):  
Sofia Nordling ◽  
Jaan Hong ◽  
Karin Fromell ◽  
Fredrik Edin ◽  
Johan Brännström ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Thrombus Formation ◽  
Innate Immune ◽  
Human Endothelial Cells ◽  
Coagulation Activation ◽  
Ischaemia Reperfusion Injury ◽  
Novel Approach ◽  
One Step ◽  
Chamber Model

SummaryIschaemia-reperfusion injury (IRI) poses a major challenge in many thrombotic conditions and in whole organ transplantation. Activation of the endothelial cells and shedding of the protective vascular glycocalyx during IRI increase the risk of innate immune activation, cell infiltration and severe thrombus formation, promoting damage to the tissue. Here, we present a novel one-step strategy to protect the vasculature by immobilisation of a unique multi-arm heparin conjugate to the endothelium. Applying a new in vitro blood endothelial cell chamber model, the heparin conjugate was found to bind not only to primary human endothelial cells but also directly to the collagen to which the cells adhered. Incubation of hypoxic endothelial cells with freshly drawn human blood in the blood chambers elicited coagulation activation reflected by thrombin anti-thrombin formation and binding of platelets and neutrophils. Immobilisation of the heparin conjugate to the hypoxic endothelial cells created a protective coating, leading to a significant reduction of the recruitment of blood cells and coagulation activation compared to untreated hypoxic endothelial cells. This novel approach of immobilising multi-arm heparin conjugates on the endothelial cells and collagen of the basement membrane ensures to protect the endothelium against IRI in thrombotic disorders and in transplantation.

Investigating Platelet Interactions in Sickle Cell Disease Using a Novel Multi-Shear "Endothelialized" Microfluidic System

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 4155-4155
Author(s):  
Margo Renee Rollins ◽  
Byungwook Ahn ◽  
Yumiko Sakurai ◽  
Jordan C Ciciliano ◽  
Wilbur A Lam
Keyword(s):  
Endothelial Cells ◽  
Sickle Cell ◽  
Whole Blood ◽  
Blood Cells ◽  
Platelet Adhesion ◽  
Blood Samples ◽  
Shear Rates ◽  
Healthy Control ◽  
Platelet Aggregates

Abstract Sickle Cell Disease (SCD) is an inherited disorder of the β-globin chain of hemoglobin, in which a single point mutation leads to decreased deformability of red blood cells (RBCs) and increased cellular adhesion to endothelium. The effect of this mutation on RBCs has been well characterized, and the interplay of endothelial cells, RBCs, and white blood cells (WBCs) have also been well characterized. However, few studies have specifically investigated how platelets interact with endothelial cells and other blood cells in the context of SCD and the role these cell fragments may have in vaso-occlusion. To that end, we utilized microfluidic technology previously developed in our lab to perform a “real time” in vitro analyses of platelet-endothelial cell interactions in SCD patient samples. This “microvasculature-on-a-chip” enables the visualization of blood cell-endothelial cell interactions under a controlled hemodynamic environment (Tsai et al, JCI, 2012). As shear stress can trigger platelet activation, we further modified and optimized our standard microfluidic devices to encompass 3 different physiologic shear rates. Our device features microchannels 50µm in diameter with human umbilical vein endothelial cells (HUVEC) confluently lining the channels; there are 12 channels in each device, grouped in 3 sets of 4 channels with graduating shear rates spanning 3 orders of magnitude (Figure 1). Our initial experiments were performed under normoxic conditions allowing characterization of platelet-endothelial interactions in an “arterial” in vitro environment. Whole blood samples were obtained from 3 patient populations: patients with HgbSS SCD on hydroxyurea (HgbSS+HU), patients with HgbSS SCD not on hydroxyurea (HgbSS-no HU), and normal healthy controls. Over 30 minutes, whole blood stained with fluorescently labeled CD41 to identify platelets and Hoeschst to identify HUVEC nuclei was perfused at a rate of 1.5µl/minute under videomicroscopy. Accumulation of platelets on the endothelialized channels and platelet aggregates were quantified based on anti-CD41 fluorescence. Within 1 minute of perfusion, HgbSS-no HU whole blood samples exhibited extensive platelet aggregates at 1 and 10 dyne/cm2 (Figure 2); this phenomenon did not occur under any of the shear conditions in blood samples from Hgb SS+HU or healthy control samples. In HgbSS-no HU blood samples, some of these “thrombi”-like aggregates were stable under flow, increased in size, and persisted for the remainder of the 30 minute experiments. In contrast, mild, uniform, platelet adhesion slowly developed at high shear conditions in Hgb SS+HU with fewer platelet aggregates forming as compared to patients with HgbSS- no HU. Healthy control samples did not exhibit this platelet aggregation. There appears to be an attenuating effect of hydroxyurea on platelets that prevents platelet clumping from occuring as frequently under various shear conditions that is not present in the Hgb SS-no HU samples (Figure 3). In conclusion, using our novel in vitro system, we have demonstrated the platelets from Hgb SS-no HU patients have a significantly increased propensity to adhere, aggregate, and accumulate in endothelialized microvasculature-sized microchannels. Interestingly, this effect appears to be attenuated in blood samples from Hgb SS+HU patients and not present in healthy controls, demonstrating that hydroxyurea appears to be an important modifier of this phenomenon. Experiments investigating the underlying mechanisms of this phenomenon, the effects of deoxygenation and the potential role of platelets in vaso-occlusion, the effects of sickle cell platelet adhesion/aggregation on endothelial function, and how hydroxyurea may or may not affect any or all of these parameters, are all currently ongoing. Figure 1 Figure 1. Figure 2 Figure 2. Figure 3 Figure 3. Disclosures No relevant conflicts of interest to declare.

Fibrinogen Adsorption, Platelet Adhesion and Thrombin Generation at Heparinized Surfaces Exposed to Flowing Blood

2002 ◽  
Vol 87 (04) ◽  
pp. 742-747 ◽  
Author(s):  
George Willems ◽  
Marco Morra ◽  
Jeffrey Keuren ◽  
Simone Wielders ◽  
Theo Lindhout
Keyword(s):  
Protein Adsorption ◽  
Whole Blood ◽  
Thrombin Generation ◽  
Platelet Adhesion ◽  
Platelet Rich Plasma ◽  
Thrombus Formation ◽  
Adhesion Assay ◽  
Flowing Blood ◽  
Fibrinogen Adsorption

SummaryThrombus formation at an artificial surface in contact with blood is a complex process that encompasses accretion of platelets from flowing blood and fibrin deposition. Platelet adhesion and fibrin formation are intimately intertwined reactions that are triggered by different sets of surface adsorbed plasma proteins. To dissect the contribution of protein adsorption and platelet adhesion to thrombin formation, a coherent study was performed with non-coated (NC) and heparin-coated (HC) surfaces. Thrombin production in whole blood, platelet adhesion and protein adsorption were studied using an amidolytic thrombin assay, a dynamic platelet adhesion assay and ellipsometry, respectively. Thrombin generation in flowing whole blood exposed to HC surfaces was greatly diminished when compared with NC surfaces. However, separate platelet adhesion and protein adsorption studies with anticoagulated whole blood revealed that platelets do not adhere because fibrinogen is not available in the protein layer that was deposited during the perfusion. These findings indicate that the in vitro thrombogenicity of a material cannot be predicted from platelet adhesion and protein adsorption data when these measurements are performed with anticoagulated blood or platelet rich plasma. Preincubation of NC and HC surfaces with fibrinogen or 2000-fold diluted plasma resulted in similar amounts of surface-bound fibrinogen and mediated massive platelet adhesion from flowing whole blood. These results indicate that a) platelet adhesion correlates with the availability of surface-bound fibrinogen and b) NC and HC surfaces are indistinguishable with respect to protein (fibrinogen) adsorption and platelet adhesion. It is apparent that the heparinized surface used in our studies exerts its anti-thrombogenic properties by neutralizing locally formed thrombin and not by reducing fibrinogen-dependent platelet adhesion.

Vitamin E reduces platelet adhesion to human endothelial cells in vitro

2000 ◽  
Vol 65 (1) ◽  
pp. 1-4 ◽  
Author(s):  
T. Szuwart ◽  
T. Brzoska ◽  
T.A. Luger ◽  
T. Filler ◽  
E. Peuker ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Vitamin E ◽  
Platelet Adhesion ◽  
Human Endothelial Cells

In Vitro Assay of Platelet Adhesiveness with Washed and Tanned Human Red Cells

1968 ◽  
Vol 20 (03/04) ◽  
pp. 384-396 ◽  
Author(s):  
G Zbinden ◽  
S Tomlin
Keyword(s):  
Platelet Adhesion ◽  
Sodium Citrate ◽  
Blood Platelets ◽  
In Vitro Assay ◽  
Red Cells ◽  
Platelet Adhesiveness ◽  
Vitro Assay ◽  
In Vitro System ◽  
Human Red Cells

SummaryAn in vitro system is described in which adhesion of blood platelets to washed and tannic acid-treated red cells was assayed quantitatively by microscopic observation. ADP, epinephrine and TAME produced a reversible increase in platelet adhesiveness which was antagonized by AMP. With Evans blue, polyanetholsulfonate, phthalanilide NSC 38280, thrombin and heparin at concentrations above 1-4 u/ml the increase was irreversible. The ADP-induced increase in adhesiveness was inhibited by sodium citrate, EDTA, AMP, ATP and N-ethylmaleimide. EDTA, AMP and the SH-blocker N-ethylmaleimide also reduced spontaneous platelet adhesion to red cells. No significant effects were observed with adenosine, phenprocoumon, 5-HT, phthalanilide NSC 57155, various estrogens, progestogens and fatty acids, acetylsalicylic acid and similarly acting agents, hydroxylamine, glucose and KCN. The method may be useful for the screening of thrombogenic and antithrombotic properties of drugs.

Perturbation of Platelet Adhesion to Endothelial Cells by Plasminogen Activation In Vitro

1997 ◽  
Vol 78 (02) ◽  
pp. 934-938 ◽  
Author(s):  
Hsiun-ing Chen ◽  
Yueh-I Wu ◽  
Yu-Lun Hsieh ◽  
Guey-Yueh Shi ◽  
Meei-Jyh Jiang ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Endothelial Cells ◽  
Platelet Adhesion ◽  
Treatment Time ◽  
Shape Change ◽  
Umbilical Vein ◽  
Tissue Type ◽  
Apical Surface ◽  
Plasminogen Activation

SummaryTo investigate whether the endothelium-platelet interactions may be altered by plasminogen activation, cultured human umbilical vein endothelial cells (ECs) were treated with tissue-type plasminogen activator (t-PA) in the presence of plasminogen, and platelet adhesion to ECs was subsequently measured by using a tapered flow chamber. Our results demonstrated that platelets adhered more readily to t-PA treated EC monolayer than to the control monolayer at all shear stress levels tested. This phenomenon was treatment time-dependent and dose-dependent, and it could be blocked by adding plasmin inhibitors, such as e-amino caproic acid and aprotinin. Adherent platelets on t-PA treated EC monolayer underwent more severe shape change than those on the control monolayer. While the extracellular matrix directly treated with t-PA attracted less platelets than the control matrix did, platelet adhesion to the matrix that was produced by t-PA-treated ECs was unaltered. These data suggest that t-PA treatment on ECs compromised antiplatelet-adhesion capability on their apical surface without altering the reactivity of their extracellular matrix towards platelets.

Desmopressin (DDAVP) Enhances Platelet Adhesion to the Extracellular Matrix of Cultured Human Endothelial Cells through Increased Expression of Tissue Factor

1997 ◽  
Vol 77 (05) ◽  
pp. 0975-0980 ◽  
Author(s):  
Angel Gálvez ◽  
Goretti Gómez-Ortiz ◽  
Maribel Díaz-Ricart ◽  
Ginés Escolar ◽  
Rogelio González-Sarmiento ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Endothelial Cells ◽  
Tissue Factor ◽  
Platelet Adhesion ◽  
Umbilical Vein ◽  
Procoagulant Activity ◽  
Experimental Conditions ◽  
Chromogenic Assay

SummaryThe effect of desmopressin (DDAVP) on thrombogenicity, expression of tissue factor and procoagulant activity (PCA) of extracellular matrix (ECM) generated by human umbilical vein endothelial cells cultures (HUVEC), was studied under different experimental conditions. HUVEC were incubated with DDAVP (1, 5 and 30 ng/ml) and then detached from their ECM. The reactivity towards platelets of this ECM was tested in a perfusion system. Coverslips covered with DD A VP-treated ECMs were inserted in a parallel-plate chamber and exposed to normal blood anticoagulated with low molecular weight heparin (Fragmin®, 20 U/ml). Perfusions were run for 5 min at a shear rate of 800 s1. Deposition of platelets on ECMs was significantly increased with respect to control ECMs when DDAVP was used at 5 and 30 ng/ml (p <0.05 and p <0.01 respectively). The increase in platelet deposition was prevented by incubation of ECMs with an antibody against human tissue factor prior to perfusion. Immunofluorescence studies positively detected tissue factor antigen on DDAVP derived ECMs. A chromogenic assay performed under standardized conditions revealed a statistically significant increase in the procoagulant activity of the ECMs produced by ECs incubated with 30 ng/ml DDAVP (p <0.01 vs. control samples). Northern blot analysis revealed increased levels of tissue factor mRNA in extracts from ECs exposed to DDAVP. Our data indicate that DDAVP in vitro enhances platelet adhesion to the ECMs through increased expression of tissue factor. A similar increase in the expression of tissue factor might contribute to the in vivo hemostatic effect of DDAVP.

Simulation of platelet adhesion and aggregation regulated by fibrinogen and von Willebrand factor

2008 ◽  
Vol 99 (01) ◽  
pp. 108-115 ◽  
Author(s):  
Koichiro Yano ◽  
Ken-ichi Tsubota ◽  
Takuji Ishikawa ◽  
Shigeo Wada ◽  
Takami Yamaguchi ◽  
...  
Keyword(s):  
Platelet Adhesion ◽  
Thrombus Formation ◽  
Simple Shear Flow ◽  
Stokesian Dynamics ◽  
General Observation ◽  
Significant Development ◽  
Platelet Adhesion And Aggregation ◽  
Von Willebrand ◽  
Willebrand Factor

SummaryWe propose a method to analyze platelet adhesion and aggregation computationally, taking into account the distinct properties of two plasma proteins, vonWillebrand factor (vWF) and fibrinogen (Fbg). In this method, the hydrodynamic interactions between platelet particles under simple shear flow were simulated using Stokesian dynamics based on the additivity of velocities. The binding force between particles mediated by vWF and Fbg was modeled using the Voigt model. Two Voigt models with different properties were introduced to consider the distinct behaviors of vWF and Fbg. Our results qualitatively agreed with the general observation of a previous in-vitro experiment, thus demonstrating that the significant development of thrombus formation in height requires not only vWF, but also Fbg. This agreement of simulation and experimental results qualitatively validates our model and suggests that consideration of the distinct roles of vWF and Fbg is essential to investigate the physiological and pathophysiological mechanisms of thrombus formation using a computational approach.

Sign in / Sign up

Export Citation Format

Share Document