[Drug Delivery to Various Body Organs via Non-blood Circulatory Pathway]

Delivery of nucleic acid therapeutics to target body organs requires injection of nanocarriers into the bloodstream. However, as such nanocarriers would also be delivered to non-target organs, low delivery efficiency to target organs and risk of unexpected effects are clear limitations of this technology. We recently applied iontophoresis (IP) for direct delivery of nucleic acid therapeutics to various organs. IP relies on a weak electric current for noninvasive transdermal drug delivery. We found that IP can deliver hydrophilic macromolecules and nanoparticles into the skin. We previously succeeded in transdermal delivery of siRNA, and subsequent knockdown (70%) of target mRNA levels in the skin via IP of siRNA (Int. J. Pharm., 383, 2010, Kigasawa et al.). Moreover, we found that cell signal activation and cleavage of intercellular junctions are induced by IP (J. Biol. Chem., 289, 2014, Hama et al.). We hypothesized that this phenomenon should be observed in not only skin but also other organs, and subsequently carried out IP of nucleic acid therapeutics to various body organs including liver, pancreas and kidney. This technique resulted in delivery of nucleic acid therapeutics into the various target body organs, and subsequent knockdown of target genes. These results suggest that direct delivery to target body organs via non-blood circulatory pathway is possible. This technology may offer a solution to the various limitations associated with current drug delivery systems (DDS).