VISUALIZATION AND ANALYSIS OF MURAL THROMBOGENESIS (PLATELET ADHESION, COLLAGEN, POLYURETHANE, DIGITAL IMAGE PROCESSING)
HUBBELL, JEFFREY ALAN
Doctor of Philosophy
Epi-fluorescence video microscopy, digital image processing, and photodiode photometry were used to visualize and analyze mural thrombogenesis on collagen coated glass, polyurethane, and nylon surfaces in contact with flowing whole blood. A parallel plate flow chamber was used as the test system, and wall shear rates of 100, 500, and 1500 sec('-1) were considered. The technique permitted real-time visualization, high resolution, quantitative, off-line measurement of the growth of individual thrombi and high resolution, quantitative, end-point measurement of the accumulation of platelets as a function of position on the surface. Thrombi grew rapidly on the collagen coated surface. These thrombi exhibited little embolization over the two minute exposure times considered. Thrombi rapidly grew and subsequently embolized from the polyurethane surface. These emboli were large for low wall shear rates and very small for high wall shear rates. Small thrombi grew on the nylon coated surface and subsequently embolized. Significant leukocyte adhesion to the nylon surface was seen after a brief stagnation period. Concentration profiles were calculated for adenosine diphosphate, thromboxane A(,2), and thrombin in the neighborhood of a single growing thrombus to evaluate the possible role of the generation and release of these substances in the mechanism of thrombus growth. Thrombin was seen to be of profound importance, even in the presence of heparin and antithrombin III. Thromboxane A(,2) was seen to be of some importance, with a lesser role for adenosine diphosphate. Concentration profiles of these same species were calculated near a large surface in contact with flowing blood. Thrombin was again seen to be of profound importance, even in the presence of heparin and antithrombin III. Thromboxane A(,2) and adenosine diphosphate were also seen to be of importance, albeit not so profound as thrombin.