Targeting of liposomes to sinusoidal liver cells: Massive uptake by liver endothelial cells via a scavenger receptor mediated process

Human serum albumin (HSA) derivatized with cis-aconitic anhydride (Aco-HSA) was covalently coupled to liposomes (Aco-HSA-Lip). Aco-HSA-Lip were cleared from the blood and taken up by the liver within 30 minutes after injection into a rat. In the liver especially endothelial cells and to a lesser extent Kupffer cells were responsible for this uptake, which could be inhibited by preinjection with poly inosinic acid. Binding and competition experiments with cultured liver endothelial and Kupffer cells revealed that the uptake of Aco-HSA-Lip was mediated by scavenger receptors. Aco-HSA-Lip may prove to be useful drugcarriers for various liver or liver endothelium associated disorders.