Naked siLNA-mediated gene silencing of lung bronchoepithelium EGFP expression after intravenous administration.

The use of systemic siRNA therapeutics for RNA interference-mediated silencing of disease genes is limited by serum instability and inadequate biodistribution. We have previously reported on the EGFP gene silencing effect of chitosan/siRNA nanoparticles in the bronchoepithelium of mice lungs following intranasal delivery and improved serum stability and reduced off-targeting effects in vitro by incorporation of locked nucleic acid (LNA). In this study, we examine the pulmonary gene silencing effect of siLNAs targeting enhanced-green-fluorescent-protein (EGFP) in lung bronchoepithelium upon intravenous delivery of naked siLNAs and upon intranasal delivery of either naked siLNA or chitosan/siLNA nanoparticles. We show that naked siLNA administered intravenously efficiently reduces the EGFP protein expression. A similar effect is obtained with intranasal delivery of chitosan nanoparticles containing siLNA whereas intranasally instilled naked siLNA did not cause a knockdown.