Cholesteryl cytofectin-oligodeoxyribonucleotide lipoplexes: Protection against serum nuclease digestion and interaction with mammalian cells in vitro
Submicron unilamellar cationic liposomes constructed from equimolar amounts of a cholesteryl cytofectin 3
[N-(N’,N’-dimethylaminopropane)-carbamoyl] cholesterol (Chol-T) and dioleoylphosphatidylethanolamine (DOPE) were shown to bind a model antisense oligodeoxyribonucleotide (ODN) dT18 in a saturable manner to afford electropositive lipoplexes. Liposomes imparted to the ODN [3H]dT18A7 full protection against nuclease catalyzed degradation in 10% foetal calf serum at 37oC for 3 h, while under the same conditions the naked ODN underwent approximately 50% degradation. Liposomes also promoted association of ODNs to Chinese hamster ovary (CHO) cells while at a liposome (+ve) : ODN (- ve) charge ratio of 1.3:1 lipoplexes were well tolerated by the human hepatoma cell line HepG2 at levels of ODN ordinarily employed in antisense ODN-mediated gene knockdown experiments. The findings of this study suggest that cationic liposomes based on the cationic cholesterol derivative Chol-T and the neutral co-lipid DOPE may be used in antisense ODN applications in mammalian cell lines grown in culture.