Iontophoresis-mediated direct delivery of nucleic acid therapeutics, without use of carriers, to internal organs via non-blood circulatory pathways.

Nanoparticle drug carriers have been employed to achieve systemic delivery of nucleic acid therapeutics, including small interfering RNA (siRNA); however, non-specific distribution and immune-related events often cause undesired adverse effects. Thus, there is a need for a new technology capable of specifically delivering nucleic acid therapeutics to desired sites. We demonstrated the utility of iontophoresis (IP) using weak electric current (0.3-0.5 mA/cm) as a local drug delivery technology. Our previous studies revealed that IP allows for transdermal permeation of nucleic acid therapeutics via induction of intercellular junction cleavage initiated by Ca influx-mediated cellular signaling activation, and subsequent cytoplasmic delivery through a unique endocytosis process in both skin and other cells. Based on these findings, we hypothesized that IP may enable direct delivery of nucleic acid therapeutics to internal organs through non-blood circulatory pathways without the use of delivery carriers. Permeation of fluorescent-labeled nucleic acids administered via IP applied to the surface of the liver and pancreas was observed in both organs, but not with topical application. IP-mediated local delivery of siRNA into the liver and pancreas significantly suppressed target mRNA expression in each organ. Moreover, IP administration of therapeutic siRNA against the molecules responsible for liver steatosis and fibrosis significantly inhibited lipid accumulation and fibrotic hepatic damage in individual model mice. These findings suggest that IP may be a useful technology to directly deliver nucleic acid therapeutics to internal organs without use of drug delivery carriers via non-blood circulatory pathways.