Role of plasma viscosity in platelet adhesion

Abstract

Platelet adhesion to the vessel wall is initiated by transport of blood platelets from the bulk flow to the wall. The process of diffusion and convection of the platelets is affected by rheological conditions such as well shear rate, red blood cell (RBC) deformability, and viscosity of the medium. To study the effect of plasma viscosity on platelet adhesion, perfusion experiments with a rectangular perfusion chamber were performed. Reconstituted blood, consisting of washed platelets and washed RBCs, was circulated through this chamber for 5 minutes at a wall shear rate of 300 s-1. Different albumin concentrations were made, to obtain different medium viscosities (0.89 to 1.85 mPa.s). Platelet adhesion decreased with increasing medium viscosity up to viscosities of 0.95 mPa.s, but increased with medium viscosity above this value. Instead of human albumin solution, different plasma viscosities were obtained by dilution of Waldenstrom plasma with buffer. Plasma was depleted of fibronectin, which gave a final plasma viscosity of 2.0 mPa.s, and was dialyzed against HEPES buffer and subsequently diluted with the dialysis buffer in different fractions (0.89 to 2.00 mPa.s). Perfusions were performed over a purified von Willebrand factor coating on glass, or over an endothelial cell matrix, preincubated with von Willebrand factor. With both surfaces, platelet adhesion was dependent on the plasma viscosity in a similar way: at low plasma viscosities, adhesion was decreased with increasing plasma viscosity, while at higher plasma viscosities, adhesion increased with plasma viscosity. Adhesion values at higher plasma viscosity or at higher human albumin concentrations could be explained by effects of the medium on the rigidity of the RBCs, since platelet adhesion is known to be increased by enhanced RBC rigidity. Effects of the medium on the deformability of the RBCs were measured separately with the laser diffraction method. These experiments confirmed that presence of human albumin or plasma in the measuring suspension increased the rigidity of RBCs. To prevent influence of the medium on the RBCs in perfusion experiments, the RBCs were fixated with glutaraldehyde. Perfusion experiments with fixated RBCs in plasma over a von Willebrand factor preincubated endothelial cell matrix, showed a consequent decrease in adhesion with increasing plasma viscosity, according to the diffusion theories, whereas the increase of adhesion at high plasma viscosities was lacking. This suggests that the latter effect was entirely due to increased transport of platelets by more rigid RBCs.

The outcome of free tissue transfers in patients with hematological diseases: 20‐year experiences in single microsurgical center

“…19 Increased number of deformed blood components, as in the cases of hereditary hematological disorders, also represents an important factor to cause thrombosis during or after microsurgical procedures. [20][21][22][23][24][25][26][27][28][29] However, in 2013, Mlodinow et al conducted multiinstitutional data analysis in free flap transfer and concluded that anemia is not a predictor of free flap failure. 30 Many traumatic injuries or chronic inflammation are known to induce reactive thrombocytosis 18,31,32 and may trigger platelet activation.…”

“…33 Several potential therapies may be considered, including platelet aggregation inhibitors such as aspirin, dextran, and pentoxifylline. [27][28][29] Low dosage of aspirin can be suggested as routine along with dextran, especially in patients with tendency for thrombosis because of their primary disease or thrombocytosis after trauma. 38 However, it is not recommended in those patients predisposed to bleeding.…”

The Relationship of Acute Myocardial Infarction With or Without ST-Segment Elevation and Viscosity

“…12,13 The lack of difference in blood viscosity between our patient and control groups, despite the significantly lower hematocrit values in patient than in control groups, may be due to the effects of drugs given to the patients with AMI on erythrocyte aggregation and blood lipid concentrations as well as to the small numbers of patients included in the study population. Fibrinogen concentration and plasma viscosity are strongly correlated, 14,15 with increases in fibrinogen concentrations associated with decreased blood flow rate and increased thrombotic affinity, both due to increased viscosity. [15][16][17][18] We found that fibrinogen levels were significantly higher in patients with AMI with than without ST-segment elevation and were higher in both the patient groups than in controls.…”

“…Fibrinogen concentration and plasma viscosity are strongly correlated, 14,15 with increases in fibrinogen concentrations associated with decreased blood flow rate and increased thrombotic affinity, both due to increased viscosity. [15][16][17][18] We found that fibrinogen levels were significantly higher in patients with AMI with than without ST-segment elevation and were higher in both the patient groups than in controls. Plasma proteins have been found to influence viscosity, and our findings of reduced albumin and globulin concentrations in patients with AMI were in agreement with the decreases in plasma proteins during AMI.…”

A New Method to Increase the Adsorption of Protein‐Bound Toxins in Artificial Liver Support Systems

“…In the simulation, the concentration of bilirubin was 19.3 mg/dL, the porosity of the activated carbon was 0.603 (15), the albumin molecular radius was 3.48 nm, the bilirubin molecular radius was 0.5 nm, the viscosity of the albumin solution was approximately 1.0 mPa·s (29), and the temperature was 25°C; other parameters can be found in the main text.…”