Highly efficient cell-mediated gene transfer using non-viral vectors and FuGene™6: in vitro and in vivo studies

The present study was undertaken to develop an efficient non-viral gene delivery system for cardiovascular gene therapy. We investigated transfection efficiency and toxic properties of the new transfection reagent, FuGene™6, and compared it with two other transfection reagents, Tfx™-50 and LipoTaxi™. For in vivo experiments, the plasmid was delivered intramuscularly via transplantation of fibroblasts transfected with plasmid and FuGene™6. Conditions for efficient gene delivery were initially studied in vitro. Human and rabbit fibroblasts were isolated from skin, cultured and transfected with phVEGF165 or pCMVβgal plasmids, coding for vascular endothelial growth factor (VEGF) or β-galactosidase, respectively. The effect of the DNA amount and the DNA:transfection reagent ratio on plasmid uptake were studied. Of the transfection reagents tested, only FuGene™6 provided high-efficiency and dose-dependent plasmid transfer both for cell-localised (β-galactosidase) and secreted (VEGF) gene products. When analysed with an MTT assay, FuGene™6 showed no toxicity at low doses. Optimised conditions were applied for in vivo reporter gene delivery. Rabbits were injected intramuscularly with ex vivo-transfected fibroblasts. As in in vitro studies, ex vivo-transfected fibroblasts showed highly efficient gene expression in vivo. Tissue sections were analysed with macrophage-specific immunostaining. No signs of inflammation were seen in the region of fibroblast injection. This study demonstrates that FuGene™6 is a highly efficient transfection reagent that may be useful for in vitro non-viral transfection of primary human and rabbit fibroblasts and for in vivo therapeutic non-viral gene delivery.