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Torres M, Betts Z, Scholey R, Elvin M, Place S, Hayes A, Dickson AJ. Long term culture promotes changes to growth, gene expression, and metabolism in CHO cells that are independent of production stability. Biotechnol Bioeng 2023; 120:2389-2402. [PMID: 37060548 DOI: 10.1002/bit.28399] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 03/28/2023] [Accepted: 04/01/2023] [Indexed: 04/16/2023]
Abstract
Phenotypic stability of Chinese hamster ovary (CHO) cells over long term culture (LTC) presents one of the most pressing challenges in the development of therapeutic protein manufacturing processess. However, our current understanding of the consequences of LTC on recombinant (r-) CHO cell lines is still limited, particularly as clonally-derived cell lines present distinct production stability phenotypes. This study evaluated changes of culture performance, global gene expression, and cell metabolism of two clonally-derived CHO cell lines with a stable or unstable phenotype during the LTC (early [EP] vs. late [LP] culture passages). Our findings indicated that LTC altered the behavior of CHO cells in culture, in terms of growth, overall gene expression, and cell metabolism. Regardless whether cells were categorized as stable or unstable in terms of r-protein production, CHO cells at LP presented an earlier decline in cell viability and loss of any observable stationary phase. These changes were parallelled by the upregulation of genes involved in cell proliferation and survival pathways (i.e., MAPK/ERK, PI3K-Akt). Stable and unstable CHO cell lines both showed increased consumption of glucose and amino acids at LP, with a parallel accumulation of greater amounts of lactate and TCA cycle intermediates. In terms of production stability, we found that decreased r-protein production in the unstable cell line directly correlated to the loss in r-gene copy number and r-mRNA expression. Our data revealed that LTC produced ubiquitious effects on CHO cell phenotypes, changes that were rooted in alterations in cell transcriptome and metabolome. Overall, we found that CHO cells adapted their cellular function to proliferation and survival during the LTC, some of these changes may well have limited effects on overall yield or specific productivity of the desired r-product, but they may be critical toward the capacity of cells to handle r-proteins with specific molecular features.
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Affiliation(s)
- Mauro Torres
- Manchester Institute of Biotechnology, Faculty of Science and Engineering, University of Manchester, Manchester, UK
- Department of Chemical Engineering, Biochemical and Bioprocess Engineering Group, University of Manchester, Manchester, UK
| | - Zeynep Betts
- Department of Biology, Kocaeli University, İzmit, Turkey
| | - Rachel Scholey
- Bioinformatics Core Facility, University of Manchester, Manchester, UK
| | - Mark Elvin
- Manchester Institute of Biotechnology, Faculty of Science and Engineering, University of Manchester, Manchester, UK
- Department of Chemical Engineering, Biochemical and Bioprocess Engineering Group, University of Manchester, Manchester, UK
| | - Svetlana Place
- Manchester Institute of Biotechnology, Faculty of Science and Engineering, University of Manchester, Manchester, UK
- Department of Chemical Engineering, Biochemical and Bioprocess Engineering Group, University of Manchester, Manchester, UK
| | - Andrew Hayes
- Genomic Technologies Core Facility, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Alan J Dickson
- Manchester Institute of Biotechnology, Faculty of Science and Engineering, University of Manchester, Manchester, UK
- Department of Chemical Engineering, Biochemical and Bioprocess Engineering Group, University of Manchester, Manchester, UK
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Population balance modelling captures host cell protein dynamics in CHO cell cultures. PLoS One 2022; 17:e0265886. [PMID: 35320326 PMCID: PMC8959726 DOI: 10.1371/journal.pone.0265886] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Accepted: 03/09/2022] [Indexed: 11/19/2022] Open
Abstract
Monoclonal antibodies (mAbs) have been extensively studied for their wide therapeutic and research applications. Increases in mAb titre has been achieved mainly by cell culture media/feed improvement and cell line engineering to increase cell density and specific mAb productivity. However, this improvement has shifted the bottleneck to downstream purification steps. The higher accumulation of the main cell-derived impurities, host cell proteins (HCPs), in the supernatant can negatively affect product integrity and immunogenicity in addition to increasing the cost of capture and polishing steps. Mathematical modelling of bioprocess dynamics is a valuable tool to improve industrial production at fast rate and low cost. Herein, a single stage volume-based population balance model (PBM) has been built to capture Chinese hamster ovary (CHO) cell behaviour in fed-batch bioreactors. Using cell volume as the internal variable, the model captures the dynamics of mAb and HCP accumulation extracellularly under physiological and mild hypothermic culture conditions. Model-based analysis and orthogonal measurements of lactate dehydrogenase activity and double-stranded DNA concentration in the supernatant show that a significant proportion of HCPs found in the extracellular matrix is secreted by viable cells. The PBM then served as a platform for generating operating strategies that optimise antibody titre and increase cost-efficiency while minimising impurity levels.
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Torres M, Dickson AJ. Reprogramming of Chinese hamster ovary cells towards enhanced protein secretion. Metab Eng 2021; 69:249-261. [PMID: 34929420 DOI: 10.1016/j.ymben.2021.12.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 10/25/2021] [Accepted: 12/14/2021] [Indexed: 12/20/2022]
Abstract
The deficient secretory phenotype of Chinese hamster ovary (CHO) cells is a major limitation for high-level production of biopharmaceuticals, particularly for those with complex molecular architectures and post-translational modifications. To improve CHO cell secretory capacity, we recently engineered CHO cell hosts to overexpress BLIMP1 (CHOB), in a cell engineering strategy that transformed the cellular machinery and led to significantly higher product yields and cell-specific productivities for different rproteins. Here, as a follow-up to our previous study, we developed new CHO cell hosts that co-overexpress BLIMP1 and XBP1s ( CHOBX ), two transcription factors that together drive the professional secretory function of antibody-producing plasma cells. We found that the CHOBX cells presented an improved performance over that of CHOB cells, with better product yields and cell-specific productivities for a recombinant IgG1 and a 'difficult-to-express' EPO-Fc fusion protein. These improvements in the CHOBX-derived cell lines resulted from a series of physiological and metabolic changes due to the synergetic co-expression of BLIMP1 and XBP1s. Firstly, cells presented an inhibited cell growth and arrested cell cycle in G1/G0 phase, features that were directly linked to BLIMP1 expression levels. Secondly, cells increased protein translation (both overall and recombinant protein), expanded the endoplasmic reticulum and improved their capacity to secrete protein more effectively. Lastly, cells showed a metabolic profile favouring energy production, with a pronounced lactate switch and increased consumption of amino acids. This study highlights the value of transcription factors for reprogramming CHO cells towards a desired phenotype, offering the potential to engineer cells with new functionalities for enhanced manufacturing of recombinant therapeutic proteins.
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Affiliation(s)
- Mauro Torres
- Manchester Institute of Biotechnology, Faculty of Science and Engineering, University of Manchester, Manchester, UK; Department of Chemical Engineering and Analytical Science, Biochemical and Bioprocess Engineering Group, University of Manchester, Manchester, UK
| | - Alan J Dickson
- Manchester Institute of Biotechnology, Faculty of Science and Engineering, University of Manchester, Manchester, UK; Department of Chemical Engineering and Analytical Science, Biochemical and Bioprocess Engineering Group, University of Manchester, Manchester, UK.
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Torres M, Dickson AJ. Combined gene and environmental engineering offers a synergetic strategy to enhance r-protein production in Chinese hamster ovary cells. Biotechnol Bioeng 2021; 119:550-565. [PMID: 34821376 DOI: 10.1002/bit.28000] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Revised: 11/08/2021] [Accepted: 11/15/2021] [Indexed: 12/14/2022]
Abstract
Environmental growth-inhibition conditions (GICs) have been used extensively for increasing cell-specific productivity (qP ) of Chinese hamster ovary (CHO) cells, with the most common being temperature downshift and sodium butyrate (NaBu) treatment. B lymphocyte-induced maturation protein-1 (BLIMP1) overexpression in CHO cells can also inhibit cell growth and increase product titers and qP . Given the similar responses, this study evaluated the individual and combined effects of BLIMP1 expression, low temperature, and NaBu treatment on culture performance, cell metabolism, and recombinant protein production of CHO cells. As expected, all three interventions decreased cell growth, arrested cells in G1/G0 cell cycle phase, and increased qP . However, CHO cells presented different responses when considering cell viability, recombinant gene expression, and cell metabolism that indicated differences in the molecular loci by which BLIMP1 and GICs generated higher productivities. Combinations of BLIMP1 expression and GICs acted synergistically to inhibit cell growth and maximize r-protein production, with the BLIMP1/NaBu condition leading to the most significant improvements in product titers and qP . This latter condition also proved to substantially increase product yields (up to 9.8 g immunoglobulin G1 [IgG1]/L and 2.2 g erythropoietin-Fc [EPO-Fc]/L) and qP (up to 179 pg/cell/day [pcd] for IgG1 and 30 pcd for EPO-Fc) in high-density perfusion cultures. These findings offered mechanistic insights about the productivity-enhancing effects of BLIMP1 and GICs, as well as their complementarity for generating highly productive processes.
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Affiliation(s)
- Mauro Torres
- Faculty of Science and Engineering, Manchester Institute of Biotechnology, University of Manchester, Manchester, UK.,Department of Chemical Engineering and Analytical Science, Biochemical and Bioprocess Engineering Group, University of Manchester, Manchester, UK
| | - Alan J Dickson
- Faculty of Science and Engineering, Manchester Institute of Biotechnology, University of Manchester, Manchester, UK.,Department of Chemical Engineering and Analytical Science, Biochemical and Bioprocess Engineering Group, University of Manchester, Manchester, UK
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Overexpression of transcription factor BLIMP1/prdm1 leads to growth inhibition and enhanced secretory capacity in Chinese hamster ovary cells. Metab Eng 2021; 67:237-249. [PMID: 34265400 DOI: 10.1016/j.ymben.2021.07.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Revised: 06/06/2021] [Accepted: 07/07/2021] [Indexed: 01/11/2023]
Abstract
Chinese hamster ovary (CHO) cells present inherent limitations for processing and secretion of large amounts of recombinant proteins, especially for those requiring complex post-translational processing. To tackle these limitations, we engineered CHO host cells (CHOK1 and CHOS) to overexpress the transcription factor BLIMP1/prdm1 (a master regulator of the highly-secreting phenotype of antibody-producing plasma cells), generating novel CHO cell lines (referred to as CHOB). The CHOB cell lines exhibited decreased cell densities, prolonged stationary phase and arrested cell cycle in G1/G0 phase but simultaneously had significantly greater product titre for recombinant IgG1 (> 2-fold increase) coupled with a significantly greater cell-specific productivities (> 3-fold increase). We demonstrated that the improved productive phenotype of CHOB cells resulted from a series of changes to cell physiology and metabolism. CHOB cells showed a significantly greater ER size and increased protein synthesis and secretion capacity compared to control cells. In addition, CHOB cells presented a metabolic profile that favoured energy production to support increased recombinant protein production. This study indicated that a cell engineering approach based on BLIMP1 expression offers great potential for improving the secretory capacity of CHO cell hosts utilised for manufacture of recombinant biopharmaceuticals. Our findings also provides a greater understanding of the relationship between cell growth and productivity, valuable generic information for improving productive phenotypes for CHO cell lines during industrial cell line development.
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