Optimization in Transfection and Stable Production of β-galactosidase in Chinese Hamster Ovary Cells

The aim for this study was to develop recombinant Chinese Hamster Ovary (CHO) cell line producing high and stable β-galactosidase by using Lipofectamine and TransFast as transfection systems. A comparison of these two gene delivery systems was made using β-galactosidase protein expression as the endpoint readout. Parameters such as lipid to DNA ratios and different amounts of Lipofectamine or DNA used were determined for optimization of transfection. In the Lipofectamine system the highest clone number was obtained from the combination of 4.5 μL Lipofectamine and 0.75 μg DNA or 2:1 charge ratio. By using TransFast, a lipid to DNA charge ratio of 2:1 is suitable for transfection. Clone TF 9 (7) that was transfected with 9 μL TransFast and 1.5 μg DNA but maintaining this 2:1 charge ratio was found to be the most productive clone in β-galactosidase production even when scaled up to 100 mL in zeocin free medium. The highest level of production for this clone and other productive clones are on the fourth day of cultivation. The highest β-galactosidase activity by subclone TF9 (7) was about 9.64 U mg-1 in 100 mL working volume of zeocin free medium. This study showed TransFast was more efficient than the Lipofectamine LTX for transfection and lipid mediated DNA delivery is an efficient mean for LacZ gene transfer into CHO cell.