547. Magnetically Driven Non-Viral Gene Delivery Efficiently Transfects Cultured Smooth Muscle Cells and Inhibits Their Growth Via Adiponectin Transgene Expression
Authors: Boris Polyak, Michael Chorny, Ivan Alferiev, Kenneth Walsh, Gary Friedman, Robert J. Levy
Journal: Molecular Therapy (2006)

Non-viral gene delivery systems present an attractive alternative to viruses due to a reduced immune response compared to viral vectors and ease of manufacture. However their clinical use is limited by their relatively low efficiency and toxic effects in non-target tissues. These limitations can be addressed by using carriers possessing targeting properties. Targeting achievable via magnetic force may provide a clinically viable solution for effective and non- toxic non-viral gene delivery. The present studies investigated the hypothesis that non-viral transfection can be achieved via magnetically driven delivery of iron oxide containing nanoparticle- pDNA complexes. Iron oxide laden polylactide (PLA)-based biodegradable nanoparticles (NP) were surface modified with polyethyleneimine. NP containing 10% and 35% iron oxide by weight had an average size of 370±20 nm and both exhibited superparamagnetic properties (magnetic remnance less than 0.5% of their magnetic saturation values), while the latter showed higher magnetization (0.64 vs. 0.21 memu at 500 Oe, respectively). The capacity of the latter NP formulation to deliver plasmid DNA was examined in cultured A10, rat aortic smooth muscle cells (SMC), using GFP as a reporter gene. NP complexed with DNA were applied to cells for 15 min under magnetic field, and their cellular uptake and gene expression were measured fluorimetrically 2 days post treatment. Intracellular NP levels were directly dose dependent in the examined NP dose range. NP application in either low or high serum conditions (10% and 50%, respectively) resulted in significant levels of transgene expression. While similar rates of NP cellular uptake were observed in low and high serum conditions, GFP expression was 1.5-2 times higher in 10% serum-containing medium. Free DNA as well as NP-DNA complexes applied in the absence of a magnetic field did not produce detectable transgene levels under these experimental conditions. Plasmid DNA encoding adiponectin, a protein strongly suppressing PDGF-BB-induced proliferation and migration of SMC, was chosen as a gene potentially therapeutically relevant for the treatment of cardiovascular disease. The effect of magnetically mediated gene transfer on cell growth was examined in subconfluent culture of A10 incubated for 15 min in DMEM supplemented with 2% FBS and 10 ng/ml of PDGF-BB with magnetic NP complexed with adiponectin plasmid. The levels of adiponectin in the medium were found to be 3.7-4.3 ng/ml two days post treatment per ELISA. A complex of magnetic NP and DNA (2.5-3.2 μg and 0.25 μg per well, respectively) significantly inhibited the growth of SMC compared to NP complexed with GFP plasmid or GFP plasmid without a promoter (60-70% vs. 10-20%) as determined by an Alamar Blue assay. It is concluded that magnetically responsive pDNA-NP complexes demonstrate increased transgene expression versus controls.