Enhanced CHO Cell-Based Transient Gene Expression with the Epi-CHO Expression System

• Published in: Molecular biotechnology 2011-06, Vol.48 (2), p.109-115
• Main Authors: Codamo, Joe, Munro, Trent P, Hughes, Benjamin S, Song, Michael, Gray, Peter P
• Format: Article
• Language: English
• Subjects: Animals; Antibodies, Monoclonal - genetics; Antibodies, Monoclonal - metabolism; Biochemistry; Biological and medical sciences; Biological products; Biological Techniques; Biotechnology; Blotting, Western; Cell Biology; Cell culture; Cellular biology; Chemistry; Chemistry and Materials Science; CHO Cells; Cricetinae; Cricetulus; DNA replication; Electrophoresis, Polyacrylamide Gel; Fundamental and applied biological sciences. Psychology; Gene expression; green fluorescent protein; Human Genetics; Hypothermia; Liposomes; Mammals; messenger RNA; Monoclonal antibodies; plasmids; Protein Science; Recombinant Proteins - genetics; Recombinant Proteins - metabolism; Reverse Transcriptase Polymerase Chain Reaction; screening; Transfection; transgenes
• ISSN: 1073-6085; 1559-0305
• DOI: 10.1007/s12033-010-9351-9

Transient gene expression systems in mammalian cells continue to grow in popularity due to their capacity to produce significant amounts of recombinant protein in a rapid and scalable manner, without the lengthy time periods and resources required for stable cell line development. Traditionally, production of recombinant monoclonal antibodies for pre-clinical assessment by transient expression in CHO cells has been hampered by low titers. In this report, we demonstrate transient monoclonal antibody titers of 140 mg/l with CHO cells using the episomal-based transient expression system, Epi-CHO. Such titers were achieved by implementing an optimized transfection protocol incorporating mild-hypothermia and through screening of a variety of chemically defined and serum-free media for their ability to support elevated and prolonged viable cell densities post-transfection, and in turn, improve recombinant protein yields. Further evidence supporting Epi-CHO’s capacity to enhance transgene expression is provided, where we demonstrate higher transgene mRNA and protein levels of two monoclonal antibodies and a destabilized enhanced green fluorescent protein with Epi-CHO compared to cell lines deficient in plasmid DNA replication and/or retention post-transfection. The results demonstrate the Epi-CHO system’s capacity for the rapid production of CHO cell-derived recombinant monoclonal antibodies in serum-free conditions.