Transfection of HEK293-EBNA1 Cells in Suspension with 293fectin for Production of Recombinant Proteins.

INTRODUCTIONFast and efficient production of recombinant proteins (r-proteins) remains a major challenge for the academic and biopharmaceutical communities. Pure r-proteins are often required in large amounts (hundreds of milligrams to gram quantities) when being developed as biotherapeutics, or in smaller quantities (milligrams) for high-throughput screening campaigns and structural or functional studies. Mammalian cells are often preferred over prokaryotic systems when expressing cDNAs of mammalian origin, due to their superior capability to conduct elaborate post-translational modifications. Large-scale transfection of mammalian cells is now establishing itself as a "must-have" technology in the scientific community, as it allows the production of milligram to gram quantities of r-proteins within a few days after cDNA cloning into the appropriate expression vector. Although calcium-mediated large-scale transfection is very effective, other methods suitable for efficient transfection of mammalian cells are easier to use. This protocol describes the steps needed for successful transfection of 293-6E cells in suspension culture in serum-free medium using 293fectin.