Leukocyte and platelet interaction with protein and endothelial cell coated model vessels

Abstract

A new technique of epi-fluorescent video microscopy has been used to continuously monitor platelet and leukocyte interactions with the lumenal surface of collagen and endothelial cell coated glass tubes. The platelets were rendered fluorescent by addition of quinacrine (10 µm) to heparinized (10 units/ml) human blood. Blood was perfused through the tubes at wall shear rates from 80 to 4000 per second. Platelets arrived as individual cells which adhered to the collagen-coated surface on contact. Subsequent platelets preferentially adhered distally and laterally to already-adherent platelets, forming wedge-shaped mural aggregates that were axially aligned. Aggregate growth downstream is consistent with a platelet-derived material, such as ADP or thromboxane A₂, emitted from adherent platelets promoting platelet accumulation. Endothelial cell surfaces were essentially non-adherent even when aspirin pre-treated.