Virus-sized self-assembling lamellar complexes between plasmid DNA and cationic micelles promote gene transfer.
Gene therapy is based on the vectorization of genes to target cells and their subsequent expression. Cationic amphiphile-mediated delivery of plasmid DNA is the nonviral gene transfer method most often used. We examined the supramolecular structure of lipopolyamine/plasmid DNA complexes under various condensing conditions. Plasmid DNA complexation with lipopolyamine micelles whose mean diameter was 5 nm revealed three domains, depending on the lipopolyamine/plasmid DNA ratio. These domains respectively corresponded to negatively, neutrally, and positively charged complexes. Transmission electron microscopy and x-ray scattering experiments on complexes originating from these three domains showed that although their morphology depends on the lipopolyamine/plasmid DNA ratio, their particle structure consists of ordered domains characterized by even spacing of 80 A, irrespective of the lipid/DNA ratio. The most active lipopolyamine/DNA complexes for gene transfer were positively charged. They were characterized by fully condensed DNA inside spherical particles (diameter: 50 nm) sandwiched between lipid bilayers. These results show that supercoiled plasmid DNA is able to transform lipopolyamine micelles into a supramolecular organization characterized by ordered lamellar domains.
Pitard
B
B
Vector Development, Rhône-Poulenc Rorer Gencell, 13 quai Jules Guesde, BP 14, 94403 Vitry-sur-seine Cedex, France. bruno.pitard@rp-rorer.fr
Aguerre
O
O
Airiau
M
M
Lachagès
A M
AM
Boukhnikachvili
T
T
Byk
G
G
Dubertret
C
C
Herviou
C
C
Scherman
D
D
Mayaux
J F
JF
Crouzet
J
J
D004270:DNA, Circular / Q000235:genetics*; D018014:Gene Transfer Techniques; D005822:Genetic Vectors; D010957:Plasmids / Q000235:genetics*; D011073:Polyamines; D014780:Viruses / Q000235:genetics* / Q000378:metabolism / Q000648:ultrastructure
D004270:DNA, Circular; D011073:Polyamines