Transfection of lung cells in vitro and in vivo: effect of antioxidants and intraliposomal bFGF

Abstract

We hypothesized that constitutive formation of reactive oxygen species by respiratory cells is a barrier to gene transfer when liposome-DNA complexes are used, by contributing to rapid degradation of plasmid DNA. When plasmid DNA is complexed to liposomes it is protected against H2O2-mediated degradation but not that mediated by the hydroxyl radical. Treatment of distal rat fetal lung epithelial cells (RFL19Ep) with the vitamin E analog Trolox (50 μM) reduced intracellular plasmid degradation. Both Trolox (50 μM) and an iron chelator, phenanthroline (0.1 μM), significantly increased transgene expression in RFL19Ep approximately twofold, consistent with a hydroxyl radical-mediated inhibition of transgene expression. When basic fibroblast growth factor (bFGF; 20 ng/ml), a growth factor with antioxidant properties, was included within liposomes, we observed a significantly greater enhancement of RFL19Ep transgene expression (∼2-fold) over that seen with Trolox or phenanthroline. Inclusion of bFGF within liposomes also significantly enhanced (∼4-fold) transgene expression in mice following intratracheal instillation.