Blood-artificial surface interaction

Interactions of blood, or more precisely of plasma macromolecules and blood cells with the vessel wall, should the latter be natural or artificial, depend upon several parameters the mechanical properties of the vascular conduit, on the one hand, the morphology and the physical and chemical characteristics of the blood-contacting surface on the other. 

Interaction and adhesion of biological surfaces are central considerations for other physiological conditions as well. Platelets, erythrocytes, the vascular endothelium and other tissues interact during thrombosis and hemostasis. Also, when erythrocytes come in contact with artificial surfaces, damage often occurs and blood trauma may result. Finally, the accumulation of cholesterol deposits on the interior walls of arteries is responsible for atherosclerosis. 

Partial or complete replacement of natural organs with prosthetic components will someday be commonplace. For instance, the design of the total artificial heart, which has had limited clinical success, involved an application of many fundamental principles already discussed as they relate to hemodynamics, biomaterials, and control. Most would agree, however, that the materials-blood-tissue interface is the nidus for some of the most serious problems preventing the development of a safe and reliable artificial heart. This reinforces the importance of investigating at the molecular level the complex interactions that occur between artificial surfaces and the physiological environment. 

Lindon JN, McManama GP, Kushner L, et al. Does the conformation of adsorbed fibrinogen dictate platelet interaction with artificial surfaces Blood 1986 68 355-362. 

Activation of platelets by contact with artificial surfaces is a key event in the thromboembolic ccanplicadcxis of prosthetic devices in omtact with the blood (11,12), but the exact mechanism of these events is n(rt fidly understood. It is known that a film of plasma protein adsrabs on artificial materials exposed to blood and that this event proceeds interaction of the surface with blood cells (12,13). The onnpositicHi of the protein film and the configuration of its molecular constituents must reli to the blood elements information describing the nature of the underlying surface. 

Salzman EW (1981) Interaction of the Blood with Natural and Artificial Surfaces, Marcel Dekker, New York, Basel... 

The change in biological response of the adsorbed fibrinogen molecule (conversion), is also noticeable with platelet adhesion studies. In confirmation of earlier studies of Zucker and Vroman (5), we found that, usually, less platelets adhered to areas of glass slides exposed to platelet-poor plasma for 3 min than areas exposed for 3 s. When, however, a gel-filtered platelet suspension was used in place of platelet-rich plasma, a dramatic difference in the number of platelets attached to the surface previously exposed to platelet-poor plasma for 3 s or 3 min occurred. Therefore, this more reproducible protocol was used to study not only the adhesion of platelets onto artificial surfaces but also as a probe of conversion. For this purpose we chose a series of block copolymers with controllable domain morphology (phase separation on a molecular scale) and different surface energies (wettability). Previous studies have shown that the degree of phase separation influences the interactions with blood components (6,7). 

Mosher, D.F. In Interaction of Blood with Natural and Artificial Surfaces Salzman, E., Ed. Dekker New York, 1981 p. 85. 

This study deals with the formation of complexes between blood clotting proteins and natural and artificial surfaces. As these surfaces are generally charged, the behavior of a basic protein, cardiotoxin (CTX), the interaction of which is strictly charge-dependent, is also reported for comparison. Two types of interface have been investigated. 

Thrombotic complications are frequently encountered when blood is exposed to the surfaces of hemodialysis devices, heart-lung machines, arterial grafts, artificial heart components and other prosthetic devices. The blood platelets are particularly vulnerable to these adverse effects which may include a decrease in platelet count, shortened platelet survival and attendant higher platelet turnover, and altered platelet function. However the interaction of platelets with an artificial surface exposed to blood must be preceded by the interaction of the molecular components of plasma, particularly the plasma proteins, with the surface (1,2). This is due to the prepon-... 

The adsorption of a layer of plasma proteins is the first event which occurs when blood is exposed to an artificial surface ( ). As a result, a platelet never sees or adheres to a bare surface. The nature of the adsorbed protein layer, which depends on the relative concentrations and mobilities of the proteins in plasma and on their affinity for the surface, will condition the subsequent platelet-surface interaction ( ). Protein adsorption to foreign surfaces has... 

The adhesion molecules (i.e., gelatin, fibronectin, coUagen, Min3) were covalently coupled to an artificial blood vessel made from PTEE. Due to unspecific adhesion of fibrin and collagen to the implant surfaces, thrombus formation and occlusion may occur in clinical use. To overcome this problem, the concept of EC cultivation on modified implant material was developed to mimic the physiological surface of blood vessels [36]. The expiration of these ceU layers strictly depends on the cell-surface interaction, which can be improved by modifying the graft surface with adhesion molecules. 

Cazenave, J. R Davies, J. A. Kazatchkine, M. D. van Aken, W. G., eds., Blood-Surface Interactions Biological Principles Underlying Hemocompatibility with Artificial Materials-, Elsevier, Amsterdam/New York/Oxford 1986. 

Blood-surface interactions are of great importance when medical polymers, such as those used in heart valves and artificial organs, are implanted into the body. When polymers come into contact with blood, complex reactions take place and can result in the formation of a blood clot. Infrared analysis has shown in ex vivo studies that during the early stages the proteins albnmin and glycoprotein are present, with fibronogen subsequently appearing. As the adsorption process continues, albumin is replaced by other proteins until a blood clot is formed. 

This book is highly recommended. This state-of-the-art text covers in detail essentially all important hematological aspects of cardiovascular device blood compatibility. In particular, Chapter 76, Interaction of blood with artificial surfaces, which considers many theoretical, experimental, and animal studies, and Chapter 77, Artificial devices in clinical practice, which describes clinical device thromboembolic complications, are of great practical value. 

Courtney JM, Lamba NMK, Sundaram S, Forbes CD (1994) Biomaterials 15 737 Salzman EW (1986) Blood material interaction In Interaction of tbe blood with natural and artificial surfaces, Dekker Inc, New York, p 39 Meyer JG (1986) Blutgerinnung und Fibrinolyse, Deutsche Arzte Verlag, Koln Baszkin A (1986) The effect of polymer surface composition and structure on adsorption of plasma proteins. In Dawids S, Bantjes A (eds) Blood compatible materials and their testing. Martinus Nijhoff Publishers, Dortrecht, p 39... 

Material surface characteristics are important for cell—material surface interactions. Three types of cell—material surface interactions can be defined, as illustrated in Fig. 7.1, which is based on the concept proposed in Ref. 76. The first one is nonfouling interactions, in which case cells fail to interact with the material surface. This type of interaction is preferred for various biomedical applications such as artificial blood vessels and valves, artificial heart devices, catheters and blood preservation bags. The second type of interactions is passive adhesion, in which case interfacial response is controlled by physicochemical interactions between the material surface, adsorbed proteins and adhering cells. Surfaces in this category inhibit cellular metabolic changes. The adherent cells remain intact and are readily detached from these surfaces with little damage. The third is bioactive cell adhesion, in which cells activate... 

Gordon, J.L., 1986. In Cazenave, J.P., Davies, J.A., Kazatchkine, M.D., van Aken, W.G. (Eds.), Blood-surface Interactions Biological Principles Underlying Haemocompatibihty with Artificial Materials. Elsevier Science Publishers (Biomedical Division), p. 5. 

Bioinert materials are materials tliat do not release any substances that are, for example, toxic or inflammatory and do not trigger a material-tissue interaction. In the case of a blood-contacting foreign material this means that the blood components do not recognize the artificial surface as artificial and thus do not initiate a foreign body reaction [41,57]. 

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