Hypercholesterolemia-induced platelet recruitment to lesion-prone sites in vivo as established by a platelet homing assay.

(A) Rabbit thoracic aortas developed prominent lesions after 12 months of a 0.125% cholesterol diet (right panel), whereas after 3 months no lesions were observed in hematoxylin/eosin staining (left panel). (B) Sudan black staining revealed no detectable lesions in en face preparations of control and 3 mo aortas (left and middle panels) used to quantify platelet homing, whereas 12 mo aortas (right panel) displayed profound lesion development at segmental artery branching points; arrows indicate mesenteric artery ostia; arrowheads, segmental artery ostia. (C) Following injection of autologous platelets labeled with the fluophor CTG, the aortas were dissected after 72 hours. They were counterstained with 1 μM CTR to facilitate recognition of the endothelial plane in en facescanning confocal microscopy. Homed platelets are detected by FITC-fluorescence and display fluorescent double-staining appearing yellow (arrows). (D) Five-fold more platelets were recruited to lesion-prone sites of cholesterol-fed rabbits compared to controls. No platelets were detected at the anterior aspect of the aorta or elsewhere outside of branching points. (E) In diet rabbits the likelihood for a segmental artery ostium to recruit platelets in 72 hours was significantly increased.