Patent ID: 7189705

Claim:
A nucleic acid-lipid particle composition for introducing a nucleic acid into a cell, said particle composition comprising: (a) a nucleic acid-lipid particle comPrising a cationic lipid, a conjugated lipid that inhibits aggregation of particles, and a nucleic acid, wherein said nucleic acid is encapsulated in a lipid bilayer of said nucleic acid-lipid particle, and wherein said conjugated lipid that inhibits aggregation of particles is a member selected from the group consisting of a PEG-lipid, an ATTA-lipid and a cationic-polymer-lipid conjugate having the formula A-W-Y I wherein: A is a lipid moiety; W is a hydrophilic polymer; and Y is a polycationic moiety; and (b) an endosomal membrane destabilizer, wherein said endosomal membrane destabilizer is Ca ++ ion.