Stimulated Release of Cholesterol from Liposomal Membranes by a PEGylated Phospholipid

Abstract

PEGylated phospholipids are commonly used to increase the blood-circulation time of liposomes by providing a steric barrier around them. This paper documents a fundamentally new property of these lipidsan ability to stimulate the release of cholesterol from phospholipid membranes. Evidence for such stimulation has been obtained by measuring the transport of dehydroergosterol (DHE), a fluorescent simulant of cholesterol, from donor liposomes made from 1-palmitoyl-2-oleoyl-<i>sn</i>-glycero-3-phosphocholine (POPC), 1,2-distearoyl-<i>sn</i>-glycero-3-phosphoethanolamine-<i>N</i>-[methoxy­(polyethylene glycol)-2000 (DSPE-PEG₂₀₀₀), and DHE to acceptor liposomes made from POPC, 1-palmitoyl-2-oleoyl-<i>sn</i>-glycero-3-phosphoglycerol (POPG), and cholesterol. The potential of PEGylated lipids to serve as novel cholesterol-lowering agents is briefly discussed