SERUM-FREE TRANSFECTION AND SELECTION IN CHINESE-HAMSTER OVARY (CHO) CELLS

In this report a method for transfection and selection of mammalian ce lls in serum-free medium is described. Chinese hamster ovary (CHO) cel ls were grown in serum-free medium in plastic dishes coated with one o f the following attachment factors: poly-D-lysine, Cell-Tak(R) (polyph enolic proteins extracted from the marine mussel Mytilus edulis), fibr onectin or laminin. Cells grown to 80% confluence were transfected wit h an expression vector encoding the hygromycin resistance gene as a se lectable marker and beta-galactosidase as the reporter gene. Transfect ants were selected using hygromycin at a concentration of 500 mug/ml. Both fibronectin and laminin supported colony formation following sele ction in serum-free medium. However, poly-D-lysine and Cell-Tak did no t. This method can, thus, be used to select for clones producing a rec ombinant product in cells that are growing in serum-free medium from t he outset to provide a better system from which to purify proteins.