Separation of liposomes from plasma components using fast protein liquid chromatography

We describe an efficient method for separating liposomes (large unilamellar vesicles, 120-150 nm diameter) from plasma lipoproteins employing fast pro tein liquid chromatography (FPLC), This method resolves very low density li poprotein (VLDL), low-density lipoprotein, high-density lipoprotein, and ot her plasma components. Selective detection of liposomes (large unilamellar vesicles, 120-150 nm diameter) was achieved using either radiolabeled or fl uorescent lipid probes, The liposomes were found to coelute with the earlie st FPLC-eluting lipoprotein fraction, VLDL. The remaining plasma lipoprotei n and protein components eluted at later times and were resolved from lipos omes and VLDL, In order to separate VLDL from liposomes, we selectively pre cipitated the VLDL fraction from plasma using tungstophosphoric acid and ma gnesium chloride, prior to separation by FPLC, Furthermore, we demonstrate that this technique can be used to separate liposomes from lipoproteins in plasma samples collected after intravenous administration of liposomes to m ice. This technique has wide application in studies of liposome stability i n blood and, in particular, for the characterization of liposomal drug carr ier systems, (C) 1999 Academic Press.