Aim To prepare the
liposomes which protect antisense oligodeoxynucleotides (ASON) against nuclease degradation and delivery ASON into cytoplasmic efficiently. Methods A
cationic derivative of cholesterol, 3β < N ( N ′, N ′ dimethylaminoethan) carbamoyl> cholesterol (DC
chol) was synthesized and used to prepare cationic liposome. The characteristics of liposomes/ASON complexes including size, drug loaded efficiency and structure were investigated.
Cellular uptake of
fluorescence labled ASON (FAM ASON) under different condition was determined by flow cytometric analysis. Denatured polyacryamide
gel electrophoresis (DPGE) was used to analyze the role of liposomes in protecting ASON. Results The mean values of pre liposomes and liposomes /ASON complexes size were 185 7 and 228 2 nm, respectively. Cationic liposomes showed a high adsorption capacity for ASON. When the +/- charge ratio exceeded 2∶1 , more than 90% of the ASON was loaded into liposomes. Agarose gel electrophoresis showed three different existence of ASON in liposomes formulation: free, absorbed and encapsulated types. Concerning cellular
Uptake, DC Chol liposomes indicated high efficient effect of increasing cellular uptake of ASON. Compared with free ASON, the total fluorescence intensity in cytoplasma was significantly enhanced. The level of increasing was largely depended on +/- charge ratio. The cellular uptake of FAM ASON decreased in the presence of serum. The cellular total fluorescence intensity in 10% and 30% fetal bovine serum of cultured medium were only 22 3% and 15 5% as that of serum free media, respectively. DPGE confirmed that free ASON was rapidly degraded by DNase I while ASON encapsulated into liposomes was efficiently protected. Conclusion The cationic DC Chol liposomes are shown to be promising carriers to deliver ASON into cytoplasma.