Observation of subcellular distribution of antisense oligonucleotide/lipid complexes by confocal laser scanning microscope

Distribution of phosphorothioate antisense oligonucleotide (S-oligo), S-oligo/lipofectin complex and S-oligo/PEG lipid complex in Hela cells was observed by a confocal laser scanning microscope. The S-oligo localized to endosome/lysosome in a punctate fluorescence pattern. In the presence of lipofectin, the S-oligo was accumulated in the nucleus of Hela cells. The S-oligo/PEG lipid complex showed both punctate fluorescence and diffuse fluorescence in the cyoplasm, but not in the nucleus. These result clearly demonstrated that the subcellular distribution of S-oligo depended on the delivery system.