Preferential binding of polyethylene glycol-coated liposomes containing a novel cationic lipid, TRX-20, to human subendthelial cells via chondroitin sulfate

Purpose. To design novel cationic liposomes, polyethylene glycol (PEG)-coat ed cationic liposomes containing a newly synthesized cationic lipid, 3,5-di pentadecyloxybenzamidine hydrochloride (TRX-20) were formulated and their c ellular binding and uptake investigated in vitro in the following cells: hu man subendothelial cells (aortic smooth muscle cells and mesangial cells) a nd human endothelial cells. Methods. Three different PEG-coated cationic liposomes were prepared by the extrusion method, and their mean particle size and zeta potential were det ermined. Rhodamine-labeled PEG-coated cationic liposomes were incubated wit h smooth muscle cells, mesangial cells, and endothelial cells at 37 degrees C for 24 h. The amounts of cellular binding and uptake of liposomes were es timated by measuring the cell-associated fluorescence intensity of rhodamin e. To investigate the binding property of the liposomes, the changes of the binding to the cells pretreated by various kinds of glycosaminoglycan lyas es were examined. Fluorescence microscopy is used to seek localization of l iposomes in the cells. Results. The cellular binding and uptake of PEG-coated cationic liposomes t o smooth muscle cells was depended strongly on the chemical species of cati onic lipids in these liposomes. Smooth muscle cells bound higher amount of PEG-coated TRX-20 liposomes than other cationic liposomes containing N-(1-( 2,3-dioleoyloxy) propyl)-N, N, N-trimethylammonium salts or N-(alpha-(trime thylammonio)acetyl)-D-glutamate chloride. Despite of the higher affinity of PEG-coated TRX-20 liposomes for subendothelial cells, their binding to end othelial cells was very small. The binding to subendothelial cells was inhi bited when cells were pretreated by certain kinds of chondroitinase, but no t by heparitinase. These results suggest that PEG-coated TRX-20 liposomes h ave strong and selective binding property to subendothelial cells by intera cting with certain kinds of chondroitin sulfate proteoglycans (not with hep aran sulfate proteoglycans) on the cell surface and in the extracellular ma trix of the cells. This binding feature was different from that reported fo r other cationic liposomes. Conclusions. PEG-coated TRX-20 liposomes can strongly and selectively bind to subendothelial cells via certain kinds of chondroitin sulfate proteoglyc ans and would have an advantage to use as a specific drug delivery system.