Facial amphipathic deoxycholic acid-modified polyethyleneimine for efficient MMP-2 siRNA delivery in vascular smooth muscle cells

Clinical applications of RNA interference-based therapeutics such as small interfering RNAs (siRNAs) have been limited mainly due to low intracellular delivery efficiency in vitro and in vivo. In this study, facially amphipathic deoxycholic acid (DA)-modified polyethyleneimine (PEI _1.8) (DA-PEI _1.8) was synthesized and used as a potent carrier system for siRNA targeted against matrix metalloproteinase-2 (MMP-2) to inhibit the migration of vascular smooth muscle cells (SMCs), which is the major pathomechanism in the development of atherosclerosis and restenosis after arterial injury. A representative facial amphipathic bile acid DA having a high membrane permeability was conjugated to the terminal amine groups of the low molecular weight PEI _1.8 via amide bonds. The DA-PEI _1.8 conjugates formed self-assembled nanoparticles with siRNA molecules in an aqueous phase and the DA-PEI _1.8/siRNA polyplexes became stabilized and condensed as particle incubation time increased from 0 to 4 h. Both cellular internalization and target gene silencing were enhanced as the DA-PEI _1.8/siRNA polyplexes stabilized. When vascular SMCs were transfected with MMP-2 siRNA, the DA-PEI _1.8/siRNA polyplex formulation led to a significant decrease in MMP-2 gene expression, resulting in the suppression of cell migration. These results suggest that the DA-PEI _1.8/MMP-2 siRNA delivery system may be useful in anti-restenotic treatment for various vasculoproliferative disorders such as atherosclerosis, in-stent restenosis, and vein graft failure.