Cell-surface dynamics, platelet adhesion

Red cell-surface interactions may play a major role in the dynamics of protein and platelet behaviour at the interface. The effect of red cells on platelet sticking has been noted widely, causing an augmentation of the rate of adhesion, probably by a combination of physical and biochemical mechanisms (40). Hellem et al (45) have observed that red cell ghosts restore retension of platelets in colunrn almost as... 

The work discussed here has shown that suspensions of platelets and red cells in a physiological medium can provide information for platelet surface interactions. Evidence is provided on the dynamic features of platelet-surface adhesion and detachment which indicates that more than one sequence of adhesion, detachment and re-adhesion can lead to the same net platelet adhesion. Surface generated substances, such as A DP and serotonin from platelets and thrombin from the coagulation pathway, may strongly influence the function of platelets approaching a surface. The supply of these substances depends on the presence of flow and continued arrival of platelets at a surface. The reactivity of surface-bound protein may be altered by platelet adhesion and detachment. This may occur as a result of deposition of cell membrane components, replacement of the original substrate with protein secreted from platelets or possibly by enzymatic digestion of surface bound protein. 

The majority of hemocompatibility studies are performed under static conditions, but some groups considered the effect of flow on platelet adhesion in dynamic experiments. As one example, randomly structured PMMA surfaces with feature sizes of 40 nm, 80 nm, and 400 nm and heights of 3nm, 13 nm, and 50 nm were investigated under flow conditions [108,109], Experiments with human whole blood showed a preferred adsorption of vWF compared to that of fibrinogen and albumin, which is in conflict with other static studies. It is apparent that different adsorption behaviors of plasma proteins can be observed under different flow conditions. The platelet adhesion was highest on those samples with the most vWF adhesion, namely the larger structures. Experiments were carried out with washed platelets and revealed other results. Platelets preferred the smaller structured surfaces for adhesion, which shows the severe influence of blood cells and plasma proteins on the adhesion behavior of platelets [108]. 

Ruckenstein, E., A. Marmur and S. R. Rakower. 1976. Sedimentation and Adhesion of Platelets from Platelet Rich Plasma onto Glass Surface. submitted for publication. Ruekenstein, E. and D. C. Prieve. 1975. Dynamics of Cell Deposition on Surfaces. J. Theor. Biol., 51, 429-438. 

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