EFFECT OF LIPIDS ON INSECT-CELL GROWTH AND EXPRESSION OF RECOMBINANT PROTEINS IN SERUM-FREE MEDIUM

The lipid emulsion components of a serum-free insect cell medium were varied and evaluated for effects on cell growth and recombinant protei n expression. The growth of High-Five(TM) cells was significantly affe cted by polyol Pluronic F-68 and Tween-80, but not by lipids. Pluronic was essential for cell growth, while Tween-80 was required to achieve maximum cell densities. A dose response effect was observed for Tween -80 with optimal cell growth at a concentration of 25 mg/l. Cholestero l had a minor effect on cell growth, but was essential for the express ion of recombinant proteins. The expression of beta-galactosidase (bet a-gal) was directly affected by cholesterol with optimal expression at a concentration of 5.4 mg/l. Vitamin E, important as an antioxidant t o stabilize lipids, did not directly affect recombinant protein expres sion. Although lipids were not required for cell growth, the presence of lipids were required during the cell growth phase in order to achie ve efficient infection with baculovirus. These studies help to define the important components, and range of concentrations, for lipid emuls ions which can effectively replace serum in insect cell culture.