Transient mammaliancell transfection with polyethylenimine (PEI)

Abstract

Standard protein expression systems, such as E. coli, often fail to produce folded, monodisperse, or functional eukaryotic proteins (see Small-scale Expression of Proteins in E. coli). The expression of these proteins is greatly benefited by using a eukaryotic system, such as mammalian cells, that contains the appropriate folding and posttranslational machinery. Here, we describe methods for both small- and large-scale transient expression in mammalian cells using polyethylenimine (PEI). We find this procedure to be more cost-effective and quicker than the more traditional route of generating stable cell lines. First, optimal transfection conditions are determined on a small-scale, using adherent cells. These conditions are then translated for use in large-scale suspension cultures. For further details on generating stable cell lines please (see Rapid creation of stable mammalian cell lines for regulated expression of proteins using the Gateway (R) Recombination Cloning Technology and Flp-In T-REx (R) lines or Generating mammalian stable cell lines by electroporation).