title: Delivery of phosphodiester oligonucleotides: can DOTAP/DOPE liposomes do the trick?
abstract: Delivering phosphodiester ONs (PO-ONs) remains an attractive but challenging goal in antisense therapy. Both in the literature and in our experiments, most cationic liposomes fail in generating an antisense effect with PO-ONs, while they succeed with chemically modified ONs such as phosphothioate ONs (PS-ONs). This work aims to explain the biological activity of PO- and PS-ONs delivered by DOTAP/DOPE liposomes based on a detailed understanding of their cell biological behavior by means of fluorescence correlation spectroscopy and confocal laser scanning microscopy. We conclude that DOTAP/DOPE liposomes are not suited to deliver PO-ONs due to the release of naked PO-ONs in the cytosol at the time of the endosomal escape of the liposomes and the subsequent rapid degradation of the naked PO-ONs. Carriers that would not release the PO-ONs upon endosomal escape but would continue to carry the PO-ONs until they arrive at the target mRNA could therefore be better suited to delivering PO-ONs. In the case of PS-ONs, the ONs are not degraded upon release at the time of the endosomal escape of the liposomes, creating a pool of intact, biologically active PS-ONs and thus making DOTAP/DOPE liposomes mainly suitable for delivering nuclease resistant ONs. However, the cells seemed to display an export pathway for removing intact PS-ONs from the cells, limiting the presence of naked PS-ONs in the nucleus to approximately 8 h following the delivery.
authors.affiliation: Laboratory of General Biochemistry and Physical Pharmacy, Ghent University, Harelbekestraat 72, 9000 Ghent, Belgium.
authors.forename: K
authors.initials: K
authors.lastname: Remaut
authors.forename: B
authors.initials: B
authors.lastname: Lucas
authors.forename: K
authors.initials: K
authors.lastname: Braeckmans
authors.forename: N N
authors.initials: NN
authors.lastname: Sanders
authors.forename: J
authors.initials: J
authors.lastname: Demeester
authors.forename: S C
authors.initials: SC
authors.lastname: De Smedt
mesh_terms: D016503:Drug Delivery Systems; D005229:Fatty Acids, Monounsaturated / Q000737:chemistry; D031541:Fluorescence Resonance Energy Transfer; D006801:Humans; D008081:Liposomes / Q000008:administration & dosage* / Q000737:chemistry; D008175:Lung Neoplasms / Q000473:pathology; D018613:Microscopy, Confocal; D009841:Oligonucleotides / Q000008:administration & dosage* / Q000737:chemistry; D016376:Oligonucleotides, Antisense / Q000008:administration & dosage* / Q000737:chemistry; D010714:Phosphatidylethanolamines / Q000737:chemistry; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D012333:RNA, Messenger / Q000737:chemistry / Q000378:metabolism; D013997:Time Factors; D014407:Tumor Cells, Cultured
chemical_list: C410262:1,2-dioleoyl-glycero-3-phosphatidyl ethanolamine; D005229:Fatty Acids, Monounsaturated; D008081:Liposomes; D009841:Oligonucleotides; D016376:Oligonucleotides, Antisense; D010714:Phosphatidylethanolamines; D000644:Quaternary Ammonium Compounds; D012333:RNA, Messenger; C116746:phosphodiester alpha; C070046:1,2-dioleoyloxy-3-(trimethylammonium)propane