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Ha TK, Òdena A, Karottki KJLC, Kim CL, Hefzi H, Lee GM, Faustrup Kildegaard H, Nielsen LK, Grav LM, Lewis NE. Enhancing CHO cell productivity through a dual selection system using Aspg and Gs in glutamine free medium. Biotechnol Bioeng 2023; 120:1159-1166. [PMID: 36562657 DOI: 10.1002/bit.28318] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 12/03/2022] [Accepted: 12/21/2022] [Indexed: 12/24/2022]
Abstract
The dominant method for generating Chinese hamster ovary (CHO) cell lines that produce high titers of biotherapeutic proteins utilizes selectable markers such as dihydrofolate reductase (Dhfr) or glutamine synthetase (Gs), alongside inhibitory compounds like methotrexate or methionine sulfoximine, respectively. Recent work has shown the importance of asparaginase (Aspg) for growth in media lacking glutamine-the selection medium for Gs-based selection systems. We generated a Gs/Aspg double knockout CHO cell line and evaluated its utility as a novel dual selectable system via co-transfection of Gs-Enbrel and Aspg-Enbrel plasmids. Using the same selection conditions as the standard Gs system, the resulting cells from the Gs/Aspg dual selection showed substantially improved specific productivity and titer compared to the standard Gs selection method, however, with reduced growth rate and viability. Following adaptation in the selection medium, the cells improved viability and growth while still achieving ~5-fold higher specific productivity and ~3-fold higher titer than Gs selection alone. We anticipate that with further optimization of culture medium and selection conditions, this approach would serve as an effective addition to workflows for the industrial production of recombinant biotherapeutics.
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Affiliation(s)
- Tae Kwang Ha
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Lyngby, Denmark
| | - Andreu Òdena
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Lyngby, Denmark
| | - Karen Julie la Cour Karottki
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Lyngby, Denmark
- Departments of Pediatrics and Bioengineering, University of California, San Diego, California, USA
| | - Che Lin Kim
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Lyngby, Denmark
| | - Hooman Hefzi
- Departments of Pediatrics and Bioengineering, University of California, San Diego, California, USA
| | - Gyun Min Lee
- Department of Biological Sciences, KAIST, Daejeon, Republic of Korea
| | - Helene Faustrup Kildegaard
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Lyngby, Denmark
| | - Lars K Nielsen
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Lyngby, Denmark
- ARC Training Centre for Biopharmaceutical Innovation Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, Queensland, Australia
| | - Lise Marie Grav
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Lyngby, Denmark
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Lyngby, Denmark
| | - Nathan E Lewis
- Departments of Pediatrics and Bioengineering, University of California, San Diego, California, USA
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Park SH, Park JH, Lee JH, Lee HM, Kang YJ, Lee EJ, Shin S, Lee GM, Kim YG. Amplification of EBNA-1 through a single-plasmid vector-based gene amplification system in HEK293 cells as an efficient transient gene expression system. Appl Microbiol Biotechnol 2020; 105:67-76. [PMID: 33191460 DOI: 10.1007/s00253-020-11001-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 10/28/2020] [Accepted: 11/03/2020] [Indexed: 12/22/2022]
Abstract
Our previous work showed that there is a limitation in the use of dihydrofolate reductase (dhfr)/methotrexate (MTX)-mediated gene amplification systems in dhfr-non-deficient HEK293 cells, as endogenous dhfr may interfere with the amplification process. In the present study, we successfully generated Epstein-Barr virus nuclear antigen-1 (EBNA-1)-amplified HEK293 cells in a dhfr-non-deficient HEK293 cell background using a single-plasmid vector-based gene amplification system with shRNA targeting the 3'-UTR of endogenous dhfr. The introduction of this shRNA efficiently downregulated the expression of endogenous dhfr in the HEK293 cells without affecting exogenous dhfr expression. The downregulation of endogenous dhfr improved the efficiency of EBNA-1 amplification, as evidenced by a comparison with the amplification extent in cells lacking shRNA expression at the same MTX concentration. The EBNA-1 expression levels from the EBNA-1-amplified clones selected in this study were higher than those obtained from EBNA-1-amplified clones that were generated using the conventional amplification in our previous study. Consistent with previous studies, EBNA-1 amplification improved the production of the Fc-fusion protein through a specific protein productivity (qp)-enhancing effect, rather than by improving cell growth or transfection efficiency. In addition, the N-glycan profiles in the Fc-fusion protein produced using this transient gene expression (TGE) system were not affected by EBNA-1 amplification. These results indicate the potential utility of EBNA-1-amplified mammalian cells, developed using a single-plasmid vector-based gene amplification system, for efficient protein production. KEY POINTS: • EBNA-1-amplified HEK293 cells were established using gene amplification system. • EBNA-1 amplification in TGE system can increase the Fc-fusion protein productivity. • EBNA-1 amplification does not affect the N-glycan profile in the Fc-fusion protein.
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Affiliation(s)
- Sun-Hye Park
- Biotherapeutics Translational Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahak-ro, Yuseong-gu, Daejeon, Korea
- Department of Bioprocess Engineering, KRIBB School of Biotechnology, Korea University of Science and Technology (UST), 217 Gajeong-ro, Yuseong-gu, Daejeon, Korea
| | - Jong-Ho Park
- Biotherapeutics Translational Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahak-ro, Yuseong-gu, Daejeon, Korea
- Department of Biological Sciences, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon, Korea
| | - Joo-Hyoung Lee
- Biotherapeutics Translational Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahak-ro, Yuseong-gu, Daejeon, Korea
- Department of Biological Sciences, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon, Korea
| | - Hoon-Min Lee
- Biotherapeutics Translational Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahak-ro, Yuseong-gu, Daejeon, Korea
- Department of Bioprocess Engineering, KRIBB School of Biotechnology, Korea University of Science and Technology (UST), 217 Gajeong-ro, Yuseong-gu, Daejeon, Korea
| | - Yeon-Ju Kang
- Biotherapeutics Translational Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahak-ro, Yuseong-gu, Daejeon, Korea
- Department of Bioprocess Engineering, KRIBB School of Biotechnology, Korea University of Science and Technology (UST), 217 Gajeong-ro, Yuseong-gu, Daejeon, Korea
| | - Eun-Ji Lee
- Biotherapeutics Translational Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahak-ro, Yuseong-gu, Daejeon, Korea
- Department of Bioprocess Engineering, KRIBB School of Biotechnology, Korea University of Science and Technology (UST), 217 Gajeong-ro, Yuseong-gu, Daejeon, Korea
| | - Seunghyeon Shin
- Department of Biological Sciences, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon, Korea
| | - Gyun Min Lee
- Department of Biological Sciences, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon, Korea.
| | - Yeon-Gu Kim
- Biotherapeutics Translational Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahak-ro, Yuseong-gu, Daejeon, Korea.
- Department of Bioprocess Engineering, KRIBB School of Biotechnology, Korea University of Science and Technology (UST), 217 Gajeong-ro, Yuseong-gu, Daejeon, Korea.
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Abstract
The emergence of CRISPR/Cas9 system as a precise and affordable method for genome editing has prompted its rapid adoption for the targeted integration of transgenes in Chinese hamster ovary (CHO) cells. Targeted gene integration allows the generation of stable cell lines with a controlled and predictable behavior, which is an important feature for the rational design of cell factories aimed at the large-scale production of recombinant proteins. Here we present the protocol for CRISPR/Cas9-mediated integration of a gene expression cassette into a specific genomic locus in CHO cells using homology-directed DNA repair.
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