Interaction blood-surface

Interactions at surfaces and interfaces also play an essential role in the design and function of clinical implants and biomedical devices. With a few recent exceptions, implants do not attach well to tissue, and the resulting mobility of the tissue-implant interface encourages chroitic inflammation. The result can be a gathering of platelets at the site, leading to a blood clot or to the formation of a fibrous capsule, or scar, around the implant (Figure 3.3). 

The in vivo tests did not give any satisfying answer to the problem of long-term contact of heparin-silicone rubber with blood. The blood-surface interaction was... 

To some extent, platelet interaction on surfaces is mediated by shear force. Therefore it is essential to screen antiplatelet dmgs under flow conditions. Two different techniques are used to monitor platelet interaction on surfaces. The classical Baumgartner technique employs denuded rabbit aorta to evaluate platelet interaction with basement membrane components (89). The flat chamber technique uses a chamber in which cover slips coated with various test materials can be exposed to flowing blood (90). One can get a layer of cell matrix components for testing, by growing endothelial cells on cover slips and stripping them off the glass surface after they reach confluency. 

Vroman et al (28) extensively studied the initial phase of blood-surface interactions. They have postulated that on hydrophilic surfaces (eg. Glass), Fg is deposited within seconds along with traces of high molecular weight kininogen (HMWK) and factor XII. Then more HMWK and factor XII arrive and displace Fg. Platelets adhere most, where fibrinogen remains. Thus, Fg plays a key role in platelet-surface attachment and subsequent thrombus formation. 

Salaman. E.W, Role ofplatdets in blood-surface interactions. Fed. Proc., 30,1503-1509(1971). 

This chapter deals with a specific test of blood-surface interaction in vitro platelet retention in a column of beads (due to platelet adhesion and aggregation). Protein adsorption precedes platelet adsorption, and thus the in vitro platelet retention test involves competitive and sequential adsorption of proteins, the outcome of which produces surfaces having widely varying degrees of platelet retention. Except in the case of thrombin (3), plasma protein absorption on these surfaces has not been studied. 

Probably no single causal mechanism functions in the calcification process of neointima-lined or smooth surface polyurethanes. Rather, surface calcification is most likely a result of the combination and interaction of mechanical and surface chemical effects at the blood-surface interface. Mechanical damage to or physical imperfections on the polymeric substrate in smooth surface devices or the neointima lining of textured bladders may be capable of inducing a deposition and mineralization process. Calcification of tissue valve leaflets has been proposed to result from the diffusion of blood elements into mechanically disrupted tissue (10), thus providing a site for mineralization to occur. Likewise, deposits of calcium-chelating proteins or lipids in defects in neointimal tissue or the polymer substrate may act as precursor binding sites for the observed mineralization. 

We have been investigating Fourier transform infrared spectroscopic methods for monitoring blood-surface interactions for over six years, during which period the following capabilities of the FT-IR technique for this application have been demonstrated ... 

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. 

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. 

Keywords Blood-surface interactions Hemocompatibility Heparin Nitric oxide Platelets Polymers... 

Surfaces can be active in inducing blood clotting, and there is much current searching for thromboresistant synthetic materials for use in surgical repair of blood vessels (see Ref. 111). It may be important that a protective protein film be strongly adsorbed [112]. The role of water structure in cell-wall interactions may be quite important as well [113]. 

Surface Tension. Interfacial surface tension between fluid and filter media is considered to play a role in the adhesion of blood cells to synthetic fibers. Interfacial tension is a result of the interaction between the surface tension of the fluid and the filter media. Direct experimental evidence has shown that varying this interfacial tension influences the adhesion of blood cells to biomaterials. The viscosity of the blood product is important in the shear forces of the fluid to the attached cells viscosity of a red cell concentrate is at least 500 times that of a platelet concentrate. This has a considerable effect on the shear and flow rates through the filter. The surface stickiness plays a role in the critical shear force for detachment of adhered blood cells. 

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