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Bokelmann C, Ehsani A, Schaub J, Stiefel F. Deciphering Metabolic Pathways in High-Seeding-Density Fed-Batch Processes for Monoclonal Antibody Production: A Computational Modeling Perspective. Bioengineering (Basel) 2024; 11:331. [PMID: 38671753 PMCID: PMC11048072 DOI: 10.3390/bioengineering11040331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2024] [Revised: 03/22/2024] [Accepted: 03/25/2024] [Indexed: 04/28/2024] Open
Abstract
Due to their high specificity, monoclonal antibodies (mAbs) have garnered significant attention in recent decades, with advancements in production processes, such as high-seeding-density (HSD) strategies, contributing to improved titers. This study provides a thorough investigation of high seeding processes for mAb production in Chinese hamster ovary (CHO) cells, focused on identifying significant metabolites and their interactions. We observed high glycolytic fluxes, the depletion of asparagine, and a shift from lactate production to consumption. Using a metabolic network and flux analysis, we compared the standard fed-batch (STD FB) with HSD cultivations, exploring supplementary lactate and cysteine, and a bolus medium enriched with amino acids. We reconstructed a metabolic network and kinetic models based on the observations and explored the effects of different feeding strategies on CHO cell metabolism. Our findings revealed that the addition of a bolus medium (BM) containing asparagine improved final titers. However, increasing the asparagine concentration in the feed further prevented the lactate shift, indicating a need to find a balance between increased asparagine to counteract limitations and lower asparagine to preserve the shift in lactate metabolism.
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Affiliation(s)
- Carolin Bokelmann
- Institute of Biochemical Engineering, University of Stuttgart, 70569 Stuttgart, Germany
| | - Alireza Ehsani
- Boehringer Ingelheim Pharma GmbH & Co.KG, Launch & Innovation, 88400 Biberach an der Riß, Germany
| | - Jochen Schaub
- Boehringer Ingelheim Pharma GmbH & Co.KG, Development Biologicals Germany, 88400 Biberach an der Riß, Germany
| | - Fabian Stiefel
- Boehringer Ingelheim Pharma GmbH & Co.KG, Development Sciences Germany, 88400 Biberach an der Riß, Germany
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Hong MS, Braatz RD. Mechanistic modeling and parameter-adaptive nonlinear model predictive control of a microbioreactor. Comput Chem Eng 2021. [DOI: 10.1016/j.compchemeng.2021.107255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Fazelkhah A, Afshar S, Braasch K, Butler M, Salimi E, Bridges G, Thomson D. Cytoplasmic conductivity as a marker for bioprocess monitoring: Study of Chinese hamster ovary cells under nutrient deprivation and reintroduction. Biotechnol Bioeng 2019; 116:2896-2905. [DOI: 10.1002/bit.27115] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 06/28/2019] [Accepted: 07/04/2019] [Indexed: 12/31/2022]
Affiliation(s)
- Azita Fazelkhah
- Department of Electrical and Computer EngineeringUniversity of Manitoba Winnipeg Canada
| | - Samaneh Afshar
- Department of Electrical and Computer EngineeringUniversity of Manitoba Winnipeg Canada
| | - Katrin Braasch
- Department of MicrobiologyUniversity of Manitoba Winnipeg Canada
| | - Michael Butler
- National Institute for Bioprocessing Research and Training Dublin Ireland
| | - Elham Salimi
- Department of Electrical and Computer EngineeringUniversity of Manitoba Winnipeg Canada
| | - Greg Bridges
- Department of Electrical and Computer EngineeringUniversity of Manitoba Winnipeg Canada
| | - Douglas Thomson
- Department of Electrical and Computer EngineeringUniversity of Manitoba Winnipeg Canada
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Afshar S, Salimi E, Fazelkhah A, Braasch K, Mishra N, Butler M, Thomson DJ, Bridges GE. Progression of change in membrane capacitance and cytoplasm conductivity of cells during controlled starvation using dual-frequency DEP cytometry. Anal Chim Acta 2019; 1059:59-67. [DOI: 10.1016/j.aca.2019.01.046] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Revised: 12/20/2018] [Accepted: 01/23/2019] [Indexed: 12/18/2022]
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5
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Ritacco FV, Wu Y, Khetan A. Cell culture media for recombinant protein expression in Chinese hamster ovary (CHO) cells: History, key components, and optimization strategies. Biotechnol Prog 2018; 34:1407-1426. [DOI: 10.1002/btpr.2706] [Citation(s) in RCA: 86] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Revised: 08/03/2018] [Accepted: 08/06/2018] [Indexed: 02/06/2023]
Affiliation(s)
- Frank V. Ritacco
- Biologics Process DevelopmentBristol‐Myers Squibb Pennington New Jersey United States
| | - Yongqi Wu
- Biologics Process DevelopmentBristol‐Myers Squibb Pennington New Jersey United States
| | - Anurag Khetan
- Biologics Process DevelopmentBristol‐Myers Squibb Pennington New Jersey United States
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Salimi E, Braasch K, Fazelkhah A, Afshar S, Saboktakin Rizi B, Mohammad K, Butler M, Bridges GE, Thomson DJ. Single cell dielectrophoresis study of apoptosis progression induced by controlled starvation. Bioelectrochemistry 2018; 124:73-79. [PMID: 30007208 DOI: 10.1016/j.bioelechem.2018.07.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 06/28/2018] [Accepted: 07/03/2018] [Indexed: 11/20/2022]
Abstract
Nutrient depletion in fed-batch cultures and at the end of batch cultures is among the main causes of stress on cells and a trigger of apoptosis. In this study, we investigated changes in the cytoplasm conductivity of Chinese hamster ovary (CHO) cells under controlled starvation. Employing a single-cell dielectrophoresis (DEP) cytometer, we measured the DEP response of CHO cells incubated in a medium without glucose and glutamine over a 48-h period. Using the measured data in conjunction with numerical simulations, we determined the cytoplasm conductivity of viable and apoptotic cell subpopulations. The results show that a small subpopulation of apoptotic cells emerges after 24 to 36 h of starvation and increases rapidly over a short period of time, <12 h. The apoptotic cells have a dramatically lower cytoplasm conductivity, ∼0.05 S/m, than viable cells, ∼0.45 S/m. Viability of starvation cultures was measured by fluorescent cytometry, DEP cytometry, and trypan blue exclusion assays. DEP, Annexin V, caspase-8, and 7-AAD assays show a similar decline in viability after 36 h of starvation and indicate a very low viability after 48 h. Trypan blue exclusion assay fails to detect early-stage viability decline and estimates a much higher viability after 48 h.
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Affiliation(s)
- Elham Salimi
- Department of Electrical and Computer Engineering, University of Manitoba, Winnipeg R3T 5V6, Canada
| | - Katrin Braasch
- Department of Microbiology, University of Manitoba, Winnipeg R3T 2N2, Canada
| | - Azita Fazelkhah
- Department of Electrical and Computer Engineering, University of Manitoba, Winnipeg R3T 5V6, Canada
| | - Samaneh Afshar
- Department of Electrical and Computer Engineering, University of Manitoba, Winnipeg R3T 5V6, Canada
| | - Bahareh Saboktakin Rizi
- Department of Electrical and Computer Engineering, University of Manitoba, Winnipeg R3T 5V6, Canada
| | - Kaveh Mohammad
- Department of Electrical and Computer Engineering, University of Manitoba, Winnipeg R3T 5V6, Canada
| | - Michael Butler
- Department of Microbiology, University of Manitoba, Winnipeg R3T 2N2, Canada; National Institute for Bioprocessing Research and Training, Dublin, Ireland
| | - Greg E Bridges
- Department of Electrical and Computer Engineering, University of Manitoba, Winnipeg R3T 5V6, Canada.
| | - Douglas J Thomson
- Department of Electrical and Computer Engineering, University of Manitoba, Winnipeg R3T 5V6, Canada
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7
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The art of CHO cell engineering: A comprehensive retrospect and future perspectives. Biotechnol Adv 2015; 33:1878-96. [DOI: 10.1016/j.biotechadv.2015.10.015] [Citation(s) in RCA: 174] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Revised: 10/21/2015] [Accepted: 10/30/2015] [Indexed: 12/14/2022]
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Butler M, Spearman M, Braasch K. Monitoring cell growth, viability, and apoptosis. Methods Mol Biol 2014; 1104:169-92. [PMID: 24297416 DOI: 10.1007/978-1-62703-733-4_12] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The accurate determination of cell growth and viability is pivotal to monitoring a bioprocess. Direct methods to determine the cell growth and/or viability in a bioprocess include microscopic counting, electronic particle counting, image analysis, in situ biomass monitoring, and dieletrophoretic cytometry. These methods work most simply when a fixed volume sample can be taken from a suspension culture. Manual microscopic counting is laborious but affords the advantage of allowing cell viability to be determined if a suitable dye is included. Electronic particle counting is a rapid total cell count method for replicate samples, but some data distortion may occur if the sample has significant cell debris or cell aggregates. Image analysis based on the use of digital camera images acquired through a microscope has advanced rapidly with the availability of several commercially available software packages replacing manual microscopic counting and viability determination. Biomass probes detect cells by their dielectric properties or their internal concentration of NADH and can be used as a continuous monitor of the progress of a culture. While the monitoring of cell growth and viability is an integral part of a bioprocess, the monitoring of apoptosis induction is also becoming more and more important in bioprocess control to increase volumetric productivity by extending bioprocess duration. Different fluorescent assays allow for the detection of apoptotic characteristics in a cell sample.Indirect methods of cell determination involve the chemical analysis of a culture component or a measure of metabolic activity. These methods are most useful when it is difficult to obtain intact cell samples. However, the relationship between these parameters and the cell number may not be linear through the phases of a cell culture. The determination of nucleic acid (DNA) or total protein can be used as an estimate of biomass, while the depletion of glucose from the media can be used as an estimate of cellular activity. The state of cellular viability may be measured by the release of an enzyme such as lactate dehydrogenase or more directly from the intracellular adenylate energy charge from cell lysates. Alternatively, radioactive techniques may be used for an accurate determination of cellular protein synthesis.
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Affiliation(s)
- Michael Butler
- Animal Cell Technology, Department of Microbiology, University of Manitoba, Winnipeg, MB, Canada
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Perley JP, Mikolajczak J, Harrison ML, Buzzard GT, Rundell AE. Multiple model-informed open-loop control of uncertain intracellular signaling dynamics. PLoS Comput Biol 2014; 10:e1003546. [PMID: 24722333 PMCID: PMC3983080 DOI: 10.1371/journal.pcbi.1003546] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Accepted: 02/07/2014] [Indexed: 01/08/2023] Open
Abstract
Computational approaches to tune the activation of intracellular signal transduction pathways both predictably and selectively will enable researchers to explore and interrogate cell biology with unprecedented precision. Techniques to control complex nonlinear systems typically involve the application of control theory to a descriptive mathematical model. For cellular processes, however, measurement assays tend to be too time consuming for real-time feedback control and models offer rough approximations of the biological reality, thus limiting their utility when considered in isolation. We overcome these problems by combining nonlinear model predictive control with a novel adaptive weighting algorithm that blends predictions from multiple models to derive a compromise open-loop control sequence. The proposed strategy uses weight maps to inform the controller of the tendency for models to differ in their ability to accurately reproduce the system dynamics under different experimental perturbations (i.e. control inputs). These maps, which characterize the changing model likelihoods over the admissible control input space, are constructed using preexisting experimental data and used to produce a model-based open-loop control framework. In effect, the proposed method designs a sequence of control inputs that force the signaling dynamics along a predefined temporal response without measurement feedback while mitigating the effects of model uncertainty. We demonstrate this technique on the well-known Erk/MAPK signaling pathway in T cells. In silico assessment demonstrates that this approach successfully reduces target tracking error by 52% or better when compared with single model-based controllers and non-adaptive multiple model-based controllers. In vitro implementation of the proposed approach in Jurkat cells confirms a 63% reduction in tracking error when compared with the best of the single-model controllers. This study provides an experimentally-corroborated control methodology that utilizes the knowledge encoded within multiple mathematical models of intracellular signaling to design control inputs that effectively direct cell behavior in open-loop.
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Affiliation(s)
- Jeffrey P. Perley
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana, United States of America
| | - Judith Mikolajczak
- Department of Medicinal Chemistry & Molecular Pharmacology, Purdue University, West Lafayette, Indiana, United States of America
| | - Marietta L. Harrison
- Department of Medicinal Chemistry & Molecular Pharmacology, Purdue University, West Lafayette, Indiana, United States of America
| | - Gregery T. Buzzard
- Department of Mathematics, Purdue University, West Lafayette, Indiana, United States of America
| | - Ann E. Rundell
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana, United States of America
- * E-mail:
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Wilczek G, Rost-Roszkowska M, Wilczek P, Babczyńska A, Szulińska E, Sonakowska L, Marek-Swędzioł M. Apoptotic and necrotic changes in the midgut glands of the wolf spider Xerolycosa nemoralis (Lycosidae) in response to starvation and dimethoate exposure. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2014; 101:157-67. [PMID: 24507141 DOI: 10.1016/j.ecoenv.2013.09.034] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Revised: 09/16/2013] [Accepted: 09/25/2013] [Indexed: 05/09/2023]
Abstract
In the present study, the intensity of degenerative changes (apoptosis, necrosis) in the cells of the midgut glands of male and female wolf spiders, Xerolycosa nemoralis (Lycosidae), exposed to natural (starvation) and anthropogenic (the organophosphorous pesticide dimethoate) stressors under laboratory conditions were compared. The spiders were collected from two differentially polluted sites, both located in southern Poland: Katowice-Welnowiec, which is heavily polluted with metals, and Pilica, the reference site. Starvation and dimethoate treatment resulted in enhancement of apoptotic and necrotic changes in the midgut glands of the spiders. The frequency of degenerative changes in starving individuals was twice as high as in the specimens intoxicated with dimethoate. The percentage of apoptotic and necrotic cells was higher in starving males than in starving females. A high intensity of necrotic changes, together with increased Cas-3 like activity and a greater percentage of cells with depolarized mitochondria, were typical of starving males from the polluted site. The cell death indices observed in females depended more strongly on the type of stressor than on previous preexposure to pollutants.
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Affiliation(s)
- G Wilczek
- Department of Animal Physiology and Ecotoxicology, Faculty of Biology and Environmental Protection, University of Silesia, Bankowa 9, Katowice 40-007, Poland.
| | - M Rost-Roszkowska
- Department of Animal Histology and Embryology, Faculty of Biology and Environmental Protection, University of Silesia, Bankowa 9, Katowice 40-007, Poland
| | - P Wilczek
- Heart Prosthesis Institute, Bioengineering Laboratory, Wolnosci 345a, Zabrze 41-800, Poland
| | - A Babczyńska
- Department of Animal Physiology and Ecotoxicology, Faculty of Biology and Environmental Protection, University of Silesia, Bankowa 9, Katowice 40-007, Poland
| | - E Szulińska
- Department of Animal Physiology and Ecotoxicology, Faculty of Biology and Environmental Protection, University of Silesia, Bankowa 9, Katowice 40-007, Poland
| | - L Sonakowska
- Department of Animal Histology and Embryology, Faculty of Biology and Environmental Protection, University of Silesia, Bankowa 9, Katowice 40-007, Poland
| | - M Marek-Swędzioł
- Department of Animal Histology and Embryology, Faculty of Biology and Environmental Protection, University of Silesia, Bankowa 9, Katowice 40-007, Poland
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11
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Braasch K, Nikolic-Jaric M, Cabel T, Salimi E, Bridges GE, Thomson DJ, Butler M. The changing dielectric properties of CHO cells can be used to determine early apoptotic events in a bioprocess. Biotechnol Bioeng 2013; 110:2902-14. [PMID: 23818314 DOI: 10.1002/bit.24976] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Revised: 05/23/2013] [Accepted: 06/03/2013] [Indexed: 12/21/2022]
Abstract
To ensure maximum productivity of recombinant proteins it is desirable to prolong cell viability during a mammalian cell bioprocess, and therefore important to carefully monitor cell density and viability. In this study, five different and independent methods of monitoring were applied to Chinese hamster ovary (CHO) cells grown in a batch culture in a controlled bioreactor to determine cell density and/or cell viability. They included: a particle counter, trypan blue exclusion (Cedex), an in situ bulk capacitance probe, an off-line fluorescent flow cytometer, and a prototype dielectrophoretic (DEP) cytometer. These various techniques gave similar values during the exponential growth phase. However, beyond the exponential growth phase the viability measurements diverged. Fluorescent flow cytometry with a range of fluorescent markers was used to investigate this divergence and to establish the progress of cell apoptosis: the cell density estimates by the intermediate stage apoptosis assay agreed with those obtained by the bulk capacitance probe and the early stage apoptosis assay viability measurements correlated well with the DEP cytometer. The trypan blue assay showed higher estimates of viable cell density and viability compared to the capacitance probe or the DEP cytometer. The DEP cytometer measures the dielectric properties of individual cells and identified at least two populations of cells, each with a distinct polarizability. As verified by comparison with the Nexin assay, one population was associated with viable (non-apoptotic) cells and the other with apoptotic cells. From the end of the exponential through the stationary and decline stages there was a gradual shift of cell count from the viable into the apoptotic population. However, the two populations maintained their individual dielectric properties throughout this shift. This leads to the conclusion that changes in bulk dielectric properties of cultures might be better modeled as shifts in cells between different dielectric sub-populations, rather than assuming a homogeneous dielectric population. This shows that bulk dielectric probes are sensitive to the early apoptotic changes in cells. DEP cytometry offers a novel and unique technology for analyzing and characterizing mammalian cells based on their dielectric properties, and suggests a potential application of the device as a low-cost, label-free, electronic monitor of physiological changes in cells.
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Affiliation(s)
- Katrin Braasch
- Department of Microbiology, University of Manitoba, Winnipeg, Manitoba, R3T 2N2, Canada
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12
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Han YK, Ha TK, Lee SJ, Lee JS, Lee GM. Autophagy and apoptosis of recombinant Chinese hamster ovary cells during fed-batch culture: Effect of nutrient supplementation. Biotechnol Bioeng 2011; 108:2182-92. [DOI: 10.1002/bit.23165] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2010] [Revised: 03/24/2011] [Accepted: 03/30/2011] [Indexed: 12/18/2022]
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Karra S, Sager B, Karim MN. Multi-Scale Modeling of Heterogeneities in Mammalian Cell Culture Processes. Ind Eng Chem Res 2010. [DOI: 10.1021/ie100125a] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Srinivas Karra
- Department of Chemical Engineering, Texas Tech University, Lubbock, Texas 79409
| | - Brian Sager
- Department of Chemical Engineering, Texas Tech University, Lubbock, Texas 79409
| | - M. Nazmul Karim
- Department of Chemical Engineering, Texas Tech University, Lubbock, Texas 79409
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Xing Z, Bishop N, Leister K, Li ZJ. Modeling kinetics of a large-scale fed-batch CHO cell culture by Markov chain Monte Carlo method. Biotechnol Prog 2010; 26:208-19. [PMID: 19834967 DOI: 10.1002/btpr.284] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Markov chain Monte Carlo (MCMC) method was applied to model kinetics of a fed-batch Chinese hamster ovary cell culture process in 5,000-L bioreactors. The kinetic model consists of six differential equations, which describe dynamics of viable cell density and concentrations of glucose, glutamine, ammonia, lactate, and the antibody fusion protein B1 (B1). The kinetic model has 18 parameters, six of which were calculated from the cell culture data, whereas the other 12 were estimated from a training data set that comprised of seven cell culture runs using a MCMC method. The model was confirmed in two validation data sets that represented a perturbation of the cell culture condition. The agreement between the predicted and measured values of both validation data sets may indicate high reliability of the model estimates. The kinetic model uniquely incorporated the ammonia removal and the exponential function of B1 protein concentration. The model indicated that ammonia and lactate play critical roles in cell growth and that low concentrations of glucose (0.17 mM) and glutamine (0.09 mM) in the cell culture medium may help reduce ammonia and lactate production. The model demonstrated that 83% of the glucose consumed was used for cell maintenance during the late phase of the cell cultures, whereas the maintenance coefficient for glutamine was negligible. Finally, the kinetic model suggests that it is critical for B1 production to sustain a high number of viable cells. The MCMC methodology may be a useful tool for modeling kinetics of a fed-batch mammalian cell culture process.
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Affiliation(s)
- Zizhuo Xing
- Biotechnology Process Development, Bristol-Myers Squibb Company, Syracuse, NY 13057, USA
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Senger RS, Karim MN. Optimization of fed-batch parameters and harvest time of CHO cell cultures for a glycosylated product with multiple mechanisms of inactivation. Biotechnol Bioeng 2007; 98:378-90. [PMID: 17385745 DOI: 10.1002/bit.21428] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Optimization of fed-batch feeding parameters was explored for a system with multiple mechanisms of product inactivation. In particular, two separate mechanisms of inactivation were identified for the recombinant tissue-type activator (r-tPA) protein. Dynamic inactivation models were written to describe particular r-tPA glycoform inactivation in the presence and absence of free-glucose. A glucose-independent inactivation mechanism was identified, and inactivation rate constants were found dependent upon the presence of glycosylation of r-tPA at N184. Inactivation rate constants of the glucose-dependent mechanism were not affected by glycosylation at N184. Fed-batch optimization was performed for r-tPA production by CHO cell culture in a stirred-tank reactor with glucose, glutamine and asparagine feed. Feeding profiles in which culture supernatant concentrations of free-glucose and amino acids (combined glutamine and asparagine) were used as control variables, were evaluated for a wide variety of set points. Simulation results for a controlled feeding strategy yielded an optimum at set points of 1.51 g L(-1) glucose and 1.18 g L(-1) of amino acids. Optimization was also performed in absence of metabolite control using fixed feed-flow rates initiate during the exponential growth phase. Fixed feed-flow results displayed a family of optimum solutions along a mass flow rate ratio of 3.15 of glucose to amino acids. Comparison of the two feeding strategies showed a slight advantage of rapid feeding at a fixed flow rate as opposed to metabolite control for a product with multiple mechanisms of inactivation.
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Affiliation(s)
- Ryan S Senger
- Department of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, USA
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Lemos WP, Serráo JE, Ramalho FS, Cola Zanuincio JC, Lacerda MC. Effect of diet on male reproductive tract of Podisus nigrispinus (Dallas) (Heteroptera: Pentatomidae). BRAZ J BIOL 2005; 65:91-6. [PMID: 16025907 DOI: 10.1590/s1519-69842005000100012] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The morphology and histology of the reproductive tract of males of the predator Podisus nigrispinus (Dallas) fed on different diets were studied. P. nigrispinus was fed on diets of: larvae of Alabama argillacea (Hübner), Tenebrio molitor L., Musca domestica L., and an artificial diet. The male reproductive tract, independent of diet, showed testes with intense red coloration in a compact, circular, or slightly oval structure. The vasa deferentia were similar in color to the testes and formed long filaments, which joined with the yellow-cream colored ejaculatory duct. The morphological characteristics of the male reproductive tract were similar under all diets, except for the artificial one. The histological studies demonstrated that independent of the diet the testes of P. nigrispinus were composed of four to six follicles. The testes with six follicles generally had four developed and two atrophied follicles. The morphological and histological differences of the testes of P. nigrispinus when fed with different prey are presented and discussed.
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Affiliation(s)
- W P Lemos
- Departamento de Biologia Animal, Universidade Federal de Viçosa, CEP 36571-000, Viçosa, Minas Gerais, Brazil
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17
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Romanenko A, Santos LO, Afonso PAFNA. Unscented Kalman Filtering of a Simulated pH System. Ind Eng Chem Res 2004. [DOI: 10.1021/ie049899+] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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18
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Neural network-based prediction and optimization of estradiol release from ethylene–vinyl acetate membranes. Comput Chem Eng 2004. [DOI: 10.1016/j.compchemeng.2004.06.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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19
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Senger RS, Karim MN. Effect of shear stress on intrinsic CHO culture state and glycosylation of recombinant tissue-type plasminogen activator protein. Biotechnol Prog 2003; 19:1199-209. [PMID: 12892482 DOI: 10.1021/bp025715f] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Shear stress in suspension culture was investigated as a possible manipulative parameter for the control of glycosylation of the recombinant tissue-type plasminogen activator protein (r-tPA) produced by recombinant Chinese hamster ovary (CHO) cell culture, grown in protein-free media. Resulting fractions of partially glycosylated, Type II, and fully glycosylated, Type I, r-tPA protein were monitored as a direct function of the shear characteristics of the culture environment. The shear-induced response of CHO culture to levels of low shear stress, where exponential growth was not obtained, and to higher levels of shear stress, which resulted in extensive cell death, were examined through manipulation of the bioreactor stirring velocity. Both apparent and intrinsic cell growth, metabolite consumption, byproduct and r-tPA production, and r-tPA glycosylation, from a variable site-occupancy standpoint, were monitored throughout. Kinetic analyses revealed a shear-stress-induced alteration of cellular homeostasis resulting in a nonlinear dependency of metabolic yield coefficients and an intrinsic cell lysis kinetic constant on shear stress. Damaging levels of shear stress were used to investigate the shear dependence of cell death and lysis, as well as the effects on the intrinsic growth rate of the culture. Kinetic models were also developed on the basis of the intrinsic state of the culture and compared to traditional models. Total r-tPA production was maximized under moderate shear conditions, as was the viable CHO cell density of the culture. However, Type II r-tPA production and the fraction of Type II glycoform production ratio was maximized under damaging levels of shear stress. Analyses of biomass production yield coefficients coupled with a plug-flow reactor model of glycan addition in the endoplasmic reticulum (ER) were used to propose an overall mechanism of decreased r-tPA protein site-occupancy glycosylation with increasing shear stress. Decreased residence time of r-tPA in the ER as a result of increased protein synthesis related to shear protection mechanisms is proposed to limit contact of site Asn184 with the membrane-bound oligosaccharyltransferase enzyme in the ER.
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Affiliation(s)
- Ryan S Senger
- Department of Chemical Engineering, Colorado State University, Fort Collins, Colorado 80523, USA
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