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

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 mu M) reduced intracellular plasmid degradation. Both Trolox (50 mu M) and an iron chelator, phenanthroline (0.1 mu M), 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. [PUBLICATION ABSTRACT]