Cell-free expression systems are an attractive platform for production of protein therapeutics as they offer potential for expedited synthesis, especially for difficult to express proteins. Although Chinese Hamster Ovary (CHO) cells are routinely optimized to stably express protein at high levels, they are not efficient for rapid, high-throughput production and screening of candidate therapeutic proteins. Here we present synthesis of a mAb (IgG1) using a commercially available CHO cell-free extract (Thermo Scientific™) which contains all the catalytic components required for transcription and translation. Unlike stable or transient transfection-based screening which requires 8-14 days for setup and execution, results are attained in as little as 24 hours. Our specific aims were to: (1) optimize the cell-free reaction conditions such as time, temperature, mixing speed, and plasmid DNA concentration to maximize heavy chain (HC) synthesis and hence IgG, (2) screen additives to enhance disulfide bond formation in the extract and confirm intact mAb formation, and (3) establish the extract as a predictable tool for ranking yields of candidate antibodies. Optimization of the reaction conditions increased HC synthesis by 200% to 100mg/L. Additives such as copper enhanced disulfide bond formation and the system ranked known high and low producing mAb sequences in the same order as seen from the CHO cell based platform. Further development of the customizable cell free platform would provide a tool for rapid high-throughput ranking of mAb producers and could also potentially be used for synthesis of difficult to express and toxic proteins.

Development of a CHO cell-free synthetic platform for production of monoclonal antibodies

251st National Meeting (2016)

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