Duration of cholesterol feeding determines NP plaque penetration in vivo.
A: 6 hours circulation in vivo with Alexa fluor-488 labeled NP in 3 month cholesterol diet rabbit aorta showing modest intimal plaque thickening and little fluorescent signal (arrow). Note lack of green-yellow autofluorescence in intima and + nuclear (DAPI stain). B: In vivo 6 hours circulation with identical NP in 9 month cholesterol diet rabbit aorta indicative of marked endothelial penetration and particle trapping (arrow). C: In vivo 6 hours circulation with identical NP in 12 month cholesterol diet rabbit aorta showing extensive NP penetration into intima (green). D: Sigmoidal fitting of fluorescence scores of aortas exposed in vivo to fluorescent NP circulating for 2 hours (open) and 6 hours (solid) on rabbits fed with cholesterol for 0 to 419 days. The temporal dependence of plaque permeability on the duration of hypercholesterolemia is well approximated with a sigmoidal function.