A columnar phase of dendritic lipid-based cationic liposome-DNA complexes for gene delivery: hexagonally ordered cylindrical micelles embedded in a DNA honeycomb lattice.
Gene therapy holds great promise as a future approach to fighting disease and is explored in worldwide clinical trials. Cationic liposome (CL)-DNA complexes are a prevalent nonviral delivery vector, but their efficiency requires improvement and the understanding of their mechanism of action is incomplete. As part of our effort to investigate the structure-transfection efficiency relationships of self-assembled CL-DNA vectors, we have synthesized a new, highly charged (16+) multivalent cationic lipid, MVLBG2, with a dendritic headgroup. Our synthetic scheme allows facile variation of the headgroup charge and the spacer connecting hydrophobic and headgroup moieties as well as gram-scale synthesis. Complexes of DNA with mixtures of MVLBG2 and neutral 1,2-dioleoyl-sn-glycerophosphatidylcholine (DOPC) exhibit the well-known lamellar phase at 90 mol % DOPC. Starting at 20 mol % dendritic lipid, however, two novel nonlamellar phases are observed by synchrotron X-ray diffraction. The structure of one of these phases, present in a narrow range of composition around 25 mol % MVLBG2, has been solved. In this novel dual lattice structure, termed H(I)C, hexagonally arranged tubular lipid micelles are surrounded by DNA rods forming a three-dimensionally continuous substructure with honeycomb symmetry. Complexes in the H(I)C phase efficiently transfect mouse and human cells in culture. Their transfection efficiency, as well as that of the lamellar complexes containing only 10 mol% dendritic lipid, reaches and surpasses that of commercially available, optimized DOTAP-based complexes. In particular, complexes containing MVLBG2 are significantly more transfectant over the entire composition range in mouse embryonic fibroblasts, a cell line empirically known to be hard to transfect.
Department of Materials, University of California, Santa Barbara, California 93106, USA.
Kai K
KK
Ewert
Heather M
HM
Evans
Alexandra
A
Zidovska
Nathan F
NF
Bouxsein
Ayesha
A
Ahmad
Cyrus R
CR
Safinya
D000818:Animals; D002412:Cations; D004247:DNA / Q000008:administration & dosage / Q000737:chemistry* / Q000235:genetics; D050091:Dendrimers / Q000008:administration & dosage / Q000737:chemistry*; D004996:Ethidium / Q000737:chemistry; D018014:Gene Transfer Techniques; D057927:Hydrophobic and Hydrophilic Interactions; D008055:Lipids / Q000008:administration & dosage / Q000737:chemistry*; D008081:Liposomes / Q000008:administration & dosage / Q000737:chemistry*; D051379:Mice; D008823:Micelles; D008958:Models, Molecular; D010713:Phosphatidylcholines / Q000008:administration & dosage / Q000737:chemistry; D010714:Phosphatidylethanolamines / Q000008:administration & dosage / Q000737:chemistry; D014162:Transfection / Q000379:methods; D014961:X-Ray Diffraction
C410262:1,2-dioleoyl-glycero-3-phosphatidyl ethanolamine; D002412:Cations; D050091:Dendrimers; D008055:Lipids; D008081:Liposomes; D008823:Micelles; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D004247:DNA; C017251:1,2-oleoylphosphatidylcholine; D004996:Ethidium