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Protein, Cellular and Soft Tissue Interactions with Polyurethanes
Published in Nina M. K. Lamba, Kimberly A. Woodhouse, Stuart L. Cooper, Polyurethanes in Biomedical Applications, 2017
Nina M. K. Lamba, Kimberly A. Woodhouse, Stuart L. Cooper
Evaluation of coagulation by measuring clotting times is based on the premise that a less thrombogenic material produces an extension of the clotting time. Polyurethanes have performed well in comparison to other biomaterials, and studies show that the clotting times are comparable to, or better than, those of silicone rubber. There appears to be little difference between the clotting times of the blood exposed to different polyurethanes.83 The adsorption of coagulation proteins, particularly those involved in the contact phase of coagulation, is an aspect of protein adsorption relevant to thrombus formation on artificial surfaces. The main interest in the system has focused upon the interactions of FXII, high molecular weight kininogen (HMWK), FXI and prekallikrein (PK). Van der Kamp and van Oeveren have shown that the amounts of kallikrein and activated FXII generated by polyurethanes are much lower than on glass, although once again, only small differences between different polyurethanes were observed.84
Biocompatibility of Powdered Materials: The Influence of Surface Characteristics
Published in Michel Nardin, Eugène Papirer, Powders and Fibers, 2006
Patrick Frayssinet, Patrice Laquerriere
Surface charge is known to activate the coagulation cascade. Initiation of the intrinsic pathway occurs when prekallikrein, high-molecular-weight kininogen, factor XI, and XII are exposed to a negatively charged surface.
A human whole-blood model to study the activation of innate immunity system triggered by nanoparticles as a demonstrator for toxicity
Published in Science and Technology of Advanced Materials, 2019
Kristina N Ekdahl, Karin Fromell, Camilla Mohlin, Yuji Teramura, Bo Nilsson
The plasma contact system is linked to both the coagulation system and the kallikrein/bradykinin system: its primary function is to maintain hemostasis, but it also has an important role in inflammation. Factor XII (FXII) is the primary recognition molecule within the contact system and in particular (but not exclusively) it binds to various negatively charged substances such as heparin, lipopolysaccharide (LPS), and biomaterials (including NPs) which leads to its autoactivation to FXIIa. FXIIa, an active protease which can activate prekallikrein to kallikrein which then releases the highly potent inflammatory mediator BK from high molecular weight kininogen (HMWK). Alternatively, FXIIa can start the intrinsic pathway of coagulation by cleaving FXI to FXIa which then initiates the generation of FXa, thrombin and subsequent fibrin formation and clotting.
Immobilizing argatroban and mPEG-NH2 on a polyethersulfone membrane surface to prepare an effective nonthrombogenic biointerface
Published in Journal of Biomaterials Science, Polymer Edition, 2019
Yanling Dai, Siyuan Dai, Xiaohui Xie, Jianping Ning
The intrinsic pathway and complement system are activated by the contact activation of high molecular weight kininogen (HMWK), prekallikrein and factor XII, and those molecules require contact with negatively charged surfaces for zymogen activation in vitro [54, 55]. The charge density is another important factor that can influence the hemocompatibility of the membrane. The surface charge properties of the unmodified and modified membranes were measured, and streaming potential measurements were carried out at pH 3–10 (1 mM KCl solution at 25 °C). As shown in Figure 6, the zeta potential of the pure PES was −18.27 ± 1.87 mV at pH 7.4 (simulating the in vivo pH). The PES-PDA membrane value decreased to −31.69 ± 1.87 mV due to the introduction of the abundant negative charges of the phenol hydroxyl groups. For the AG-immobilized PES-PDA membrane, the zeta potential further declines to −52.84 ± 1.76 mV, which might be related to the –COOH group of at AG. Electrically neutral mPEG-NH2 had a shadowing effect on the negative charges, contributing to an increase of in zeta potential (−15.34 ± 1.74 mV). Some researchers proposed that the presence of negative charges on the membrane surface cause electrostatic repulsion with negatively charged components of the blood, such as proteins, erythrocytes and platelets. Others [51, 56, 57] reported that the contact phase activation after the blood contacts with the negatively charged surface was improved via neutralizing the electronegative charges.
In Vitro models for thrombogenicity testing of blood-recirculating medical devices
Published in Expert Review of Medical Devices, 2019
Within seconds of blood exposure, biomaterial surfaces rapidly adsorb serum proteins onto their surface. These proteins desorb and are exchanged for higher binding affinity proteins in a process known as the Vroman Effect. Figure 1 illustrates the pro-thrombotic events catalyzed by biomaterial contact and the Vroman pattern: albumin, immunoglobulin G (IgG), fibrinogen, and high molecular weight kininogen (HMWK) [15]. Platelets interacting with these bound proteins adhere to the material and upregulate membrane-bound phosphatidylserine [16]. The downstream pro-thrombotic processes from platelet activation are illustrated in Figure 2. When serum proenzymes such as prothrombin bind at this active site, zymogen-protease conversions produce the active form of the enzyme, thrombin [17–19]. In platelet aggregates, thrombin amplifies the coagulation response. A positive feedback loop is created that increases platelet activation through platelet activation factor (PAF), proteinase-activated receptor (PAR) 1 and 4 on platelet membranes [20]. Platelets also degranulate, releasing cytokines [21] and develop pseudopodia to strengthen adherence to the surface and other platelets [22]. Thromboxane A2 diffuses across the platelet plasma membrane and acts as an activator for other platelets [23]. Under flow conditions, platelets are captured through interaction with von Willebrand factor (vWF). This interaction is mediated through two receptors: GPIb-IX-V and platelet integrin (αIIbβ3). Active thrombin cleaves at least two sites on the fibrinogen molecule making non-covalent interactions between fibrinogen molecules [24,25] producing aggregated insoluble fibrin fibers. The fibers are crosslinked by Factor XIII [26] to form an aggregated structure that can trap platelets, red blood cells, and thrombin by binding at two distinct binding sites [20]. The fibrin-mediated clot is susceptible to fibrinolysis via plasmin, an enzyme protease [24].