title: Characterization of cationic liposome formulations designed to exhibit extended plasma residence times and tumor vasculature targeting properties.
abstract: Cationic liposomes exhibit a propensity to selectively target tumor-associated blood vessels demonstrating potential value as anti-cancer drug delivery vehicles. Their utility however, is hampered by their biological instability and rapid elimination following i.v. administration. Efforts to circumvent rapid plasma elimination have, to date, focused on decreasing cationic lipid content and incorporating polyethylene glycol (PEG)-modified lipids. In this study we wanted to determine whether highly charged cationic liposomes with surface-associated PEG could be designed to exhibit extended circulation lifetimes, while retaining tumor vascular targeting properties in an HT29 colorectal cancer xenograft model. Cationic liposomes prepared of DSPC, cationic lipids (DODAC, DOTAP, or DC-CHOL), and DSPE-PEG(2000) were studied. Our results demonstrate that formulations prepared with 50 mol% DODAC or DC-CHOL, and 20 mol% DSPE-PEG(2000) exhibited circulation half-lives ranging from 6.5 to 12.5 h. Biodistribution studies demonstrated that DC-CHOL formulations prepared with DSPE-PEG(2000) accumulated threefold higher in s.c. HT29 tumors than its PEG-free counterpart. Fluorescence microscopy studies suggested that the presence of DSPE-PEG(2000) did not adversely affect liposomal tumor vasculature targeting. We show for the first time that it is achievable to design highly charged, highly pegylated (20 mol% DSPE-PEG(2000)) cationic liposomes which exhibit both extended circulation lifetimes and tumor vascular targeting properties.
authors.affiliation: Department of Advanced Therapeutics, British Columbia Cancer Research Centre, 675 West 10th Avenue, Vancouver, BC, Canada. eho@bccrc.ca
authors.forename: Emmanuel A
authors.initials: EA
authors.lastname: Ho
authors.forename: Euan
authors.initials: E
authors.lastname: Ramsay
authors.forename: Mihaela
authors.initials: M
authors.lastname: Ginj
authors.forename: Malathi
authors.initials: M
authors.lastname: Anantha
authors.forename: Isaiah
authors.initials: I
authors.lastname: Bregman
authors.forename: Jonathan
authors.initials: J
authors.lastname: Sy
authors.forename: Janet
authors.initials: J
authors.lastname: Woo
authors.forename: Maryam
authors.initials: M
authors.lastname: Osooly-Talesh
authors.forename: Donald T
authors.initials: DT
authors.lastname: Yapp
authors.forename: Marcel B
authors.initials: MB
authors.lastname: Bally
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents; D002412:Cations / Q000627:therapeutic use*; D002626:Chemistry, Pharmaceutical; D002784:Cholesterol / Q000031:analogs & derivatives; D004304:Dosage Forms; D016503:Drug Delivery Systems / Q000379:methods*; D005260:Female; D008055:Lipids; D008081:Liposomes / Q000097:blood*; D051379:Mice; D010714:Phosphatidylethanolamines; D011092:Polyethylene Glycols; D020849:Raloxifene Hydrochloride; D014018:Tissue Distribution
chemical_list: D000970:Antineoplastic Agents; D002412:Cations; D004304:Dosage Forms; D008055:Lipids; D008081:Liposomes; D010714:Phosphatidylethanolamines; C070648:3-(N-(N',N'-dimethylaminoethane)carbamoyl)cholesterol; C038089:1,2-distearoylphosphatidylethanolamine; D011092:Polyethylene Glycols; D020849:Raloxifene Hydrochloride; D002784:Cholesterol