Macrophage-Targeting Gene Delivery Using a Micelle Composed of Mannose-Modified Lipid with Triazole Ring and Dioleoyl Trimethylammonium Propane

Gene carriers with cell specific ligand molecules are needed for the treatment of several diseases. Mannose is known to be recognized and incorporated into the cells through mannose recognition lectins that are exclusively expressed on macrophages. In this study, we synthesized two types of mannose-modified lipids with different stereoisomer (α-mannose and β-mannose). To make a complex with plasmid DNA (pDNA), termed “lipoplex,” we prepared a two-component micelle made from cationic lipid; dioleoyltrimethylammoniumpropane (DOTAP); and mannose-modified lipid (D/α-Man or D/β-Man). The prepared D/α-Man lipoplexes were able to bind to one of the α-mannose lectins concanavalin A (ConA) immobilized on gold substrate in the quartz-crystal microbalance sensor cell. D/β-Man lipoplexes did not show any frequency changes. These results indicate that the mannose residues were exposed on the lipoplexes, leading to not only the binding to ConA but also the prevention of nonspecific interactions with proteins. Both lipoplexes showed high transfection efficiencies to RAW264.7 cells which have several kinds of mannose lectins. This delivery system to macrophages may overcome the problems for gene therapy and may be used for the treatment of immune diseases involved in macrophages.

The transfection efficiency of calix[4]arene-based lipids: the role of the alkyl chain length

Calix[4]arene-based lipids with the C6 alkyl chain length exhibited the highest transfection efficiency among all lipoplexes comprising the lipids with different alkyl chain lengths and plasmid DNA.

The role of the helper lipid dioleoylphosphatidylethanolamine (DOPE) for DNA transfection cooperating with a cationic lipid bearing ethylenediamine

Gene therapy is expected to treat various incurable diseases including viral infections, autoimmune disorders, and cancers. Cationic lipids (CL) have been used as carriers of therapeutic DNAs for gene therapy because they can form a complex with DNA and such a complex can be incorporated into cells and transport the bound DNA to cytosol. The CL/DNA complexes are called lipoplexes and categorized as a non-viral vector. Lipoplexes are often prepared by adding a neutral phospholipid dioleoylphosphatidylethanolamine (DOPE) to CL in order to enhance transfection. However, the role of DOPE is not fully understood. We synthesized a new CL having an ethylenediamine cationic head group, denoted by DA, and found that addition of DOPE to DA achieved a good efficiency, almost in the similar level of commonly used transfection reagent Lipofectamine 2000 (Invitrogen). The composition of DA:DOPE=1:1 showed the highest efficiency. This lipoplex showed structural transition when pH was changed from 7 to 4, corresponding pH lowering in late endosome, while DOPE itself showed structural transition at more basic pH around 8. The present data showed that the DOPE/DA composition determines the structural transition pH and choosing a suitable pH, i.e., a suitable composition, is essential to increase the transfection efficiency.