[Development of a novel artificial gene delivery system multifunctional envelope-type nano device for gene therapy].

For efficient gene delivery to the nucleus, nonviral vectors need to overcome several barriers such as the plasma membrane, endosomal membrane, and nuclear membrane. To overcome these obstacles, it is necessary to equip the delivery system with various functional devices. However, it is difficult to package all such functional devices into a single system to exert each of their functions at the appropriate time and at the correct location. Thus our group proposed a new packaging concept, "programmed packaging." A multifunctional envelope-type nano device (MEND) was developed for use as an efficient nonviral system for the delivery of plasmid DNA (pDNA), oligodeoxynucleotide (ODN), and siRNA using octaarginine (R8) as an internalizing ligand based on the programmed packaging. The R8-modified MEND (R8-MEND) encapsulating pDNA showed significantly high transfection activity comparable to that of adenovirus, and the uptake pathway of R8-MEND was macropinocytosis, which can avoid lysosomal degradation. R8-MEND successfully delivered gene to hair follicles after in vivo topical application to mouse skin. Moreover, R8-MEND encapsulating anti-luciferase ODN using protamine showed a 90% antisense effect, and R8-MEND encapsulating siRNA condensed with stearylated R8 significantly silenced luciferase activity. Our group thus succeeded in the development of R8-MEND based on programmed packaging, and MEND is a promising new delivery system for pDNA and functional nucleic acids.