Pharmacokinetic analysis of the uptake of liposomes by macrophages and foam cells in vitro and their distribution to atherosclerotic lesions in mice

In order to evaluate the efficacy of liposomes as a drug carrier for atherosclerotic therapy, a pharmacokinetic analysis of the uptake of liposomes by macrophages and foam cells in vitro and their distribution to atherosclerotic lesions in mice was carried out. In brief, liposomes of three particle sizes (500, 200 and 70 nm) were prepared, and the uptake of liposomes by these cells in vitro and the aortic distribution following intravenous administration to atherogenic mice were examined. The internalization rate constant calculated by measuring uptake and binding was size-dependent in both types of cells in vitro. The aortic clearance (CLa) was size-independent in atherogenic mice and the CLa of 200 nm particles was the highest. Surprisingly, the aortic distribution in vivo did not correspond with the internalization to macrophages and foam cells in vitro. These results suggest that there is an optimal size for the distribution of liposomes to atherosclerotic lesions.