pH-sensitive, cationic liposomes: A new synthetic virus-like vector

We describe the use of cationic, pH-sensitive liposomes to mediate the efficient transfer of DNA into a variety of cells in culture, Cationic lipids, containing an amine with a pK within the physiologic range of 4.5 to 8, were synthesized and incorporated with dioleoylphosphatidylethanolamine into liposomes, Acid conditions promoted DNA-binding, DNA-incorporation, and DNA-induced fusion by these cationic, pH-sensitive liposomes. Transfection efficiency in cultured cells was dependent on endosomal acidification in a manner akin to acidic-induced endosomal release of viruses, These liposomes constitute a promising new class of reagents for gene therapy.