| Co-Investigator(Kenkyū-buntansha) |
OHGA Yoshinobu Wako Pure Chemical Industries, Ltd., Chief, 試薬開発部, 主任
NIIDOME Takuro Nagasaki University, Department of Materials Science, Research Associate, 大学院・生産科学研究科, 助手 (20264210)
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| Research Abstract |
The development of a non-viral gene delivery system into cells is an important key to realize the safe delivery of therapeutic genes without the side effects often pointed out for viral vectors. We have shown that dendritic poly (L-lysine) of the 6th generation (KG6) shows high transfection efficiency into several cultivated cells with low cytotoxicity. Here, to investigate the effect of substituting terminal cationic groups on the gene delivery into cells, we synthesized KGR6 and KGH6, in which terminal amino acids were replaced by arginines and histidines, respectively. DNA-binding analysis showed that KGR6 could bind to the plasmid DNA as strongly as KG6, whereas KGH6 showed decreased binding ability. KGR6 showed 3-to 12-fold higher transfection efficiency into several cultivated cells than KG6. In contrast, KGH6 showed no transfection efficiency. However, once KGH6 was mixed with the DNA under acidic conditions (pH 5.0), DNA-complexes were formed and showed high transfection efficiency comparable to KG6-mediated transfection. DNA-complexes of KGH6 formed under acidic conditions were 1-2 μm and spherical, and relatively stable under neutral conditions. The size and spherical shape of the complexes were the same as those of KG6. The unique character of KGH6 will be one of the basic and valuable tools which will enable us to construct a functional gene transfection system in vitro and in vivo.
To evaluate the potential of KG6 as a non-viral gene carrier that works in vivo, we investigated the biodistribution of plasmid DNA delivered with KG6 in mice after intravenous administration. The plasmid DNA complexes with KG6 circulated in the blood for 3 h after intravenous injection. The stealth character of DNA complexes with KG6 in the blood would cause an enhanced permeability and retention (EPR) effect in the tumor. KG6 is expected to be a promising candidate that enables functional gene delivery in vivo.
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