Title

Unsaturated cationic ortho esters for endosome permeation in gene delivery

Document Type

Article

Publication Title

Journal of Medicinal Chemistry

ISSN

0022-2623

Volume

50

Issue

18

DOI

10.1021/jm060128c

First Page

4269

Last Page

4278

Publication Date

8-10-2007

Abstract

Two cleavable cationic lipids were designed to trigger the fusogenicity and membrane permeation of their lipoplexes in endosomes via the formation of inverted hexagonal phases (HII). Both lipids contain a cationic head group and an unsaturated hydrophobic dioleylglycerol moiety joined together by a linear or a cyclic ortho ester linker. At pH 7.4, the lipids formed stable complexes with plasmid DNA together with the conelike helper lipid 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE). The decrease of pH enhanced the hydrolysis of the ortho ester linkers, which removed the cationic head groups and caused the aggregation of the lipoplexes. At pH 5.5, the cationic lipid N-[2-methyl-2-(1‘,2‘-dioleylglyceroxy)dioxolan-4-yl]methyl-N,N,N-trimethylammonium iodide (2) with a cyclic ortho ester linker showed exceptional pH-sensitivity and triggered its lipoplex to permeate model biomembranes within the time span of endosome processing prior to lysosomal degradation. Lipid 2 significantly improved gene transfection in cultured cells compared to the pH-insensitive control lipid 1,2-dioleoyl-3-trimethylammoniopropane