Biodistribution of liposomes containing synthetic galactose-terminated diacylglyceryl-poly(ethyleneglycol)s

• Published in: Biochimica et biophysica acta 1997-06, Vol.1326 (2), p.329-341
• Main Authors: Shimada, Kazuhiko, Kamps, Jan A.A.M, Regts, Joke, Ikeda, Kiyoshi, Shiozawa, Tatsushi, Hirota, Sadao, Scherphof, Gerrit L
• Format: Article
• Language: English
• Subjects: Acetylgalactosamine - pharmacology; Agglutination; Animals; Cell-specific drug targeting; Diglycerides - metabolism; Fixed aqueous layer thickness; Galactolipids; Galactose - metabolism; Galactose receptor; Glycolipids - chemical synthesis; Glycolipids - metabolism; Hepatocyte; Kupffer cell; Kupffer Cells - metabolism; Lectin; Lectins - pharmacology; Lipid Bilayers; Liposomes - chemistry; Liposomes - metabolism; Liposomes - pharmacokinetics; Liver - metabolism; Liver macrophage; Magnetic Resonance Spectroscopy; Male; N-acetylgalactosamine; Phosphatidylethanolamines - metabolism; Plant Lectins; Polyethylene Glycols - metabolism; Rats; Receptors, Cell Surface - metabolism; Spleen - metabolism; Sterically stabilized liposome
• ISSN: 0005-2736; 0006-3002; 1879-2642
• DOI: 10.1016/S0005-2736(97)00036-9

We describe the synthesis of biodegradable poly(ethyleneglycol)-coupled galactolipids in which the galactose moiety is separated from a diacylglyceride lipid anchor by poly(ethylene glycol) chains of 10, 20 or 40 oxyethylene residues (PEG 10/20/40). These Gal-PEG lipids (Gal-PEG-Lip) were incorporated in the bilayer of liposomes. The surface exposure of the galactose was investigated by aggregation experiments with ricinus communis agglutinin 120. Only the liposomes containing the PEG 10 galactolipid aggregated with the lectin. Therefore liposomes were prepared containing Gal-PEG 10-Lip and a trace amount of [ 3H]cholesteryl oleyl ether with an average diameter of approximately 100 nm and injected intravenously into rats. The Gal-PEG 10-Lip liposomes were cleared from plasma with a T1/2 of 0.3 h. Identically sized and composed control liposomes without the Gal-PEG 10-Lip had a T1/2 of approximately 12 h. The rapid plasma elimination of the Gal-PEG 10-Lip liposomes could be attributed entirely to increased uptake by the liver amounting to more than 90% of injected dose. Uptake by the spleen was decreased to less than 1% of injected dose. A single injection of N-acetylgalactosamine 1 min prior to Gal-PEG-Lip liposome administration reduced the initial rate of plasma clearance to control levels. The increased liver uptake was almost entirely attributable to increased uptake by the Kupffer cells. Incorporation of PEG-DSPE in the Gal-PEG 10-Lip liposomes only partially reversed the effect of the galactolipid with respect to liver and spleen uptake as well as intrahepatic distribution. These experiments demonstrate that liposome surface-exposed galactose residues, even if attached at the distal end of a poly(ethyleneglycol) chain anchored in the liposomal bilayer are effectively recognized by the galactose particle receptor on the Kupffer cells but fail to achieve significant targeting to the asialoglycoprotein receptor on the hepatocytes.