Fibrinogen and von Willebrand factor mediated platelet adhesion to polystyrene under flow conditions

Abstract

The roles of adsorbed fibrinogen (Fg) and von Willebrand factor (VWF) in mediating platelet adhesion to synthetic surfaces under flow were investigated using polystyrene (PS) as a model hydrophobic surface. We measured platelet adhesion to PS pre-adsorbed with Fg, VWF, normal plasma, afibrinogenemic plasma, VWF-deficient plasma and deficient plasmas with various concentrations of added Fg or VWF. Platelets in a red blood cell suspension were passed through a flow chamber at either low (50 or 100 s(-1)) or high (500 or 1000 s(-1)) shear. Adhesion to PS pre-adsorbed with afibrinogenemic plasma was very low under both low and high shear conditions, but was restored in a dose-dependent manner with addition of Fg. Less than 20 ng/cm(2)of adsorbed Fg was sufficient to support full-scale platelet adhesion under flow. At high shear rate, platelet adhesion on PS pre-adsorbed with VWF-deficient plasma was much less than on PS pre-adsorbed with normal plasma, but adhesion to PS pre-adsorbed with VWF-deficient plasma with added VWF was very similar to adhesion to PS pre-adsorbed with normal plasma. At low shear, adhesion to PS pre-adsorbed with VWF-deficient plasma was the same as on PS pre-adsorbed with normal plasma. As little as 1 ng/cm(2) of VWF adsorbed from plasma made platelet adhesion higher under high shear than under low shear. The effects of adsorbed Fg and VWF on the morphologies of platelets that adhered from suspensions flowing at high shear rates were also investigated. The lack of either Fg or VWF resulted in marked decreases in the extent of platelet spreading. Real-time observation of platelet adhesion under an epifluorescent microscope showed that platelets adhered to the surface in a linear pattern aligned in the direction of flow under high shear conditions.

Nitric oxide releasing material adsorbs more fibrinogen

“…This verifies that the increase seen in the work by the Bartlett group is likely influenced to the release of NO from the surface and not the surface properties as previously thought . Fibrinogen is an active protein in the coagulation cascade, the increase of fibrinogen adsorption to a surface is currently viewed as leading to an increase in clot formation . We find that there is an increase in the amount of fibrinogen adsorbed to the NO‐releasing surface when compared to that of the control.…”

“…22 Fibrinogen is an active protein in the coagulation cascade, the increase of fibrinogen adsorption to a surface is currently viewed as leading to an increase in clot formation. 47,48 We find that there is an increase in the amount of fibrinogen adsorbed to the NO-releasing surface when compared to that of the control. This is in contrast to a study done by Charville et al 18 where they see that the adsorption of fibrinogen to control and NO-releasing xerogels remains constant.…”

The attenuation of platelet and monocyte activation in a rabbit model of extracorporeal circulation by a nitric oxide releasing polymer

“…In a shear flow system of platelet rich plasma, Zhang et al [60] showed that platelets adhere to biomaterials through a mechanism mediated by both fibrinogen and von Willebrand’s factor. The presence of plasma proteins like von Willebrand’s factor augment the ability of activated platelets to adhere to artificial surfaces.…”

Fibrinogen adsorption to biomaterials

“…In subsequent studies, we further investigated the role of Fg and vWf on platelet adhesion from washed platelet‐red cell suspensions under flow conditions . All of these studies showed a major role for vWf in promoting platelet adhesion under high flow conditions.…”

“…In subsequent studies, we further investigated the role of Fg and vWf on platelet adhesion from washed platelet-red cell suspensions under flow conditions. 8,48–50 All of these studies showed a major role for vWf in promoting platelet adhesion under high flow conditions. Thus, for example, platelet adhesion to surfaces preadsorbed with normal plasma is greatly increased when the shear rate is increased from 50 to 500 sec −1 because of more rapid transport of the platelets to the surface at higher shear rate.…”