Protamine-modified DDAB lipid vesicles promote gene transfer in the presence of serum

Cationic lipid vesicle-mediated gene transfer has become common for in vitr o gene delivery. However, the transfection efficiency is often impaired by serum. DDAB (dimethyldioctadecyl ammonium bromide) lipid vesicle-mediated g ene transfer, which we previously reported, has the same problem. To overco me this obstacle, we here report a novel transfection vehicle using protami ne-modified DDAB Lipid vesicles. While free protamine was simply added to t he DNA/lipid complex in the previous study, in the present method the prota mine is chemically conjugated to stearic acid and incorporated into DDAB Li pid vesicles. Gene transfer was not significantly inhibited in 10% serum-co ntaining medium by this method for the transfection of cultured cells. Prot amine-modified DDAB lipid vesicles also enhanced virus transduction efficie ncy in the presence of serum using a replication-defective retroviral vecto r. Furthermore, the vesicles allowed efficient gene transfer for avian embr yos in vivo. These results indicate that the method is useful for the produ ction of transgenic animals and gene therapy.