Target specific optimization of cationic lipid-based systems for pulmonary gene therapy.
OBJECTIVE
Cationic lipids are capable of transferring foreign genes to the pulmonary epithelium in vivo. It is becoming increasingly clear that factors other than lipid molecular structure also influence efficiency of delivery using cationic lipid systems. This study is aimed at evaluating the effect of formulation variables such as cationic lipid structure, cationic lipid/DNA ratio, particle size, co-lipid content and plasmid topology on transgene expression in the lung.


METHODS
The effect of varying the surface and colloidal properties of cationic lipid-based gene delivery systems was assessed by intratracheal instillation into rats. An expression plasmid encoding chloramphenicol acetyl transferase (CAT) was used to measure transgene expression.


RESULTS
Cationic lipid structure, cationic lipid/DNA ratio, particle size, co-lipid content and topology of the plasmid, were found to significantly affect transgene expression. Complexation with lipids was found to have a protective effect on DNA integrity in bronchoalveolar lavage fluid (BALF). DNA complexed with lipid showed enhanced persistence in rat lungs as measured by quantitative polymerase chain reaction.


CONCLUSIONS
Fluorescence microscopy analysis indicated that the instilled formulation reaches the lower airways and alveolar region. Data also suggests cationic lipid-mediated gene expression is primarily localized in the lung parenchyma and not infiltrating cells isolated from the BALF.
Deshpande
D
D
GENEMEDICINE, INC., The Woodlands, Texas 77381-4248, USA. deshpd@genemedicine.com
Blezinger
P
P
Pillai
R
R
Duguid
J
J
Freimark
B
B
Rolland
A
A
D000818:Animals; D004247:DNA / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D004563:Electrochemistry; D015870:Gene Expression; D018014:Gene Transfer Techniques; D015316:Genetic Therapy; D005822:Genetic Vectors; D050356:Lipid Metabolism; D008055:Lipids / Q000737:chemistry*; D008168:Lung / Q000378:metabolism; D008171:Lung Diseases / Q000503:physiopathology / Q000628:therapy*; D008297:Male; D008856:Microscopy, Fluorescence; D009690:Nucleic Acid Conformation; D010316:Particle Size; D010957:Plasmids / Q000737:chemistry / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D013499:Surface Properties
D008055:Lipids; D004247:DNA