Full Deacylation of Polyethylenimine Dramatically Boosts Its Gene Delivery Efficiency and Specificity to Mouse Lung

• Published in: Proceedings of the National Academy of Sciences - PNAS 2005-04, Vol.102 (16), p.5679-5684
• Main Authors: Thomas, Mini, Lu, James J., Ge, Qing, Zhang, Chengcheng, Chen, Jianzhu, Klibanov, Alexander M.
• Format: Article
• Language: English
• Subjects: Acylation; Animals; Biological Sciences; Cell Line, Tumor; Cultured cells; DNA; Gene expression; Gene Expression Regulation; Gene Transfer Techniques; Humans; Influenza, Human - drug therapy; Influenza, Human - genetics; Lung - metabolism; Lungs; Mice; Nitrogen; Orthomyxoviridae - drug effects; Orthomyxoviridae - metabolism; Plasmids; Polyethyleneimine - chemistry; Polyethyleneimine - metabolism; Polyethyleneimine - therapeutic use; RNA, Small Interfering - genetics; RNA, Small Interfering - metabolism; RNA, Small Interfering - pharmacology; RNA, Small Interfering - therapeutic use; Small interfering RNA; Spleen; Transfection; Viruses
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.0502067102

High-molecular-mass polyethylenimines (PEIs) are widely used vectors for nucleic acid delivery. We found that removal of the residual N-acyl moieties from commercial linear 25-kDa PEI enhanced its plasmid DNA delivery efficiency 21 times in vitro, as well as 10,000 times in mice with a concomitant 1,500-fold enhancement in lung specificity. Several additional linear PEIs were synthesized by acid-catalyzed hydrolysis of poly(2-ethyl-2-oxazoline), yielding the pure polycations. PEI87 and PEI217 exhibited the highest efficiency in vitro: 115-fold and 6-fold above those of the commercial and deacylated PEI25s, respectively; moreover, PEI87 delivered DNA to mouse lung as efficiently as the pure PEI25 but at a lower concentration and with a 200-fold lung specificity. These improvements stem from an increase in the number of protonatable nitrogens, which presumably results in a tighter condensation of plasmid DNA and a better endosomal escape of the PEI/DNA complexes. As a validation of the potential of such linear, fully deacylated PEIs in gene therapy for lung diseases, systemic delivery in mice of the complexes of a short interfering RNA (siRNA) against a model gene, firefly luciferase, and PEI25 or PEI87 afforded a 77% and 93% suppression of the gene expression in the lungs, respectively. Furthermore, a polyplex of a siRNA against the influenza viral nucleocapsid protein gene and PEI87 resulted in a 94% drop of virus titers in the lungs of influenza-infected animals.