In vitro design and characterization of the nonviral gene delivery vector iopamidol, protamine, ethiodized oil reagent.

PURPOSE: To demonstrate cellular selectivity toward hepatoma cells and compare the efficiency of gene delivery of a novel nonviral vector of iopamidol, protamine, and ethiodized oil reagents (VIPER). MATERIALS AND METHODS: Rat hepatocellular carcinoma (HCC) cells were transfected in triplicate under varying conditions by using firefly luciferase as a reporter gene. Conditions included variations of a protamine:DNA (P:D) complex (20:1, 50:1, 100:1, 200:1 mass ratios), iopamidol (0%, 10%, 33%), and ethiodized oil (0%, 1%, 2%, 4%, 8%, and 16%). The conditions affording efficient gene transfer and ease of translation to in vivo studies were selected for cell line comparison (HCC cells vs hepatocytes). Adenoviral transduction was compared with nonviral vector transfection. RESULTS: At low concentrations, ethiodized oil increased transfection efficiency regardless of P:D mass ratio. However, high concentrations resulted in significant attenuation. Unexpectedly, the addition of iopamidol to P:D complexes markedly improved transfection efficiency. When using an optimal P:D, iopamidol, and ethiodized oil solution, DNA transfection of normal liver and tumor cells showed significant selectivity for tumor cells. In the context of hepatoma cells, transfection efficiency with the nonviral vector was better than 10(4) pfu adenovirus. CONCLUSIONS: The development and characterization of the VIPER system provides a possible alternative to viral gene therapy of HCC.