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Werner NS, Weber W, Fussenegger M, Geisse S. A gas-inducible expression system in HEK.EBNA cells applied to controlled proliferation studies by expression of p27(Kip1). Biotechnol Bioeng 2007; 96:1155-66. [PMID: 17058277 DOI: 10.1002/bit.21235] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
We describe an efficient inducible gene expression system in HEK.EBNA cells, a well-established cell system for the rapid transient expression of research-tool proteins. The transgene control system of choice is the novel acetaldehyde-inducible regulation (AIR) technology, which has been shown to modulate transgene levels following exposure of cells to acetaldehyde. For application in HEK.EBNA cells, AlcR transactivator plasmids were constructed and co-expressed with the secreted alkaline phosphatase (SEAP) gene under the control of a chimeric mammalian promoter (P(AIR)) for acetaldehyde-regulated expression. Several highly inducible transactivator cell lines were established. Adjustable transgene induction by gaseous acetaldehyde led to high induction levels and tight repression in transient expression trials and in stably transfected HEK.EBNA cell lines. Thus, the AIR technology can be used for inducible expression of any desired recombinant protein in HEK.EBNA cells. A possible application for inducible gene expression is a controlled proliferation strategy. Clonal HEK.EBNA cell lines, expressing the fungal transactivator protein AlcR, were engineered for gas-adjustable expression of the cell-cycle regulator p27(Kip1). We show that expression of p27(Kip1) via transient or stable transfection led to a G1-phase specific growth arrest of HEK.EBNA cells. Furthermore, production pools engineered for gas-adjustable expression of p27(Kip1) and constitutive expression of SEAP showed enhanced productive capacity.
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Affiliation(s)
- Nicola Susann Werner
- Novartis Institutes for BioMedical Research, Discovery Technologies/Biomolecules Production, WSJ 506.3.04, CH-4002 Basel, Switzerland
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2
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Milutinović S, Plavljanić E, Trkulja V. Comparison of two epoetin brands in anemic hemodialysis patients: results of two efficacy trials and a single-dose pharmacokinetic study. Fundam Clin Pharmacol 2006; 20:493-502. [PMID: 16968421 DOI: 10.1111/j.1472-8206.2006.00433.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Epoetin alpha is recombinant human erythropoietin with established efficacy and safety in the treatment of renal anemia. Epoetin omega is recombinant erythropoietin that differs from epoetin alpha in the sugar moiety. We compared the two epoetins in two 12-week efficacy studies (S1, S2) with twice-weekly dosing, and a single-dose crossover pharmacokinetic (PK) study in severely anemic hemodialysis patients. Epoetins were delivered subcutaneously in all studies. S1 was randomized (omega n = 39, alpha n = 38), while S2 included the patients from S1 (omega n = 32, alpha n = 24) with 'switched' treatments (omegaleft arrow over right arrowalpha). In the intent-to-treat analysis, average weekly difference in hemoglobin vs. the baseline value was higher in omega-treated patients in both studies: 1.94 +/- 0.81 vs. 1.23 +/- 0.62 g/dL in S1 and 1.44 +/- 0.72 vs. 0.95 +/- 0.62 g/dL in S2. The unadjusted and adjusted omega-alpha differences in S1 were 0.71 g/dL (95% CI 0.38-1.04; P < 0.001) and 0.78 g/dL (95% CI 0.49-1.08; P < 0.001), respectively. Differences in S2 were 0.48 g/dL (95% CI 0.11-0.86; P = 0.012) and 0.46 g/dL (95% CI 0.1-0.82; P = 0.025), unadjusted and adjusted, respectively. Average weekly epoetin dose was lower in the omega groups in both studies: 87 +/- 25 vs. 108 +/- 21 IU/kg in S1 and 106 +/- 25 vs. 125 +/- 20 IU/kg in S2. The unadjusted and adjusted omega-alpha differences in S1 were -21 IU/kg (95% CI -32 to -11; P < 0.001) and -24 IU/kg (95% CI -35 to -13; P < 0.001), respectively. Differences in S2 were -19 IU/kg (95% CI -31 to -6; P = 0.006) and -15 IU/kg (95% CI -28 to -2; P = 0.04), unadjusted and adjusted, respectively. In the PK study (n = 17), the peak and total exposure to epoetin after 50 IU/kg of either drug was approximately twice greater for epoetin omega: C(max) omega/alpha 2.19 (95% CI 1.55-3.11), AUC omega/alpha 2.24 (95% CI 1.64-3.06). Epoetins were comparably well tolerated. In hemodialysis patients, subcutaneous epoetin omega apparently provides greater bioavailability and anti-anemic effect per administered dose (IU) than epoetin alpha.
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Affiliation(s)
- Slobodan Milutinović
- Department of Nephrology and Clinical Pharmacology Research Unit, Sveti Duh General Hospital, Sveti Duh 64, 10000 Zagreb, Croatia
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Trummer E, Fauland K, Seidinger S, Schriebl K, Lattenmayer C, Kunert R, Vorauer-Uhl K, Weik R, Borth N, Katinger H, Müller D. Process parameter shifting: Part II. Biphasic cultivation-A tool for enhancing the volumetric productivity of batch processes using Epo-Fc expressing CHO cells. Biotechnol Bioeng 2006; 94:1045-52. [PMID: 16736532 DOI: 10.1002/bit.20958] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Regulation of cell growth and protein expression potentially results in a sustainable enhancement of the volumetric productivity in a fermentation process. Following a biphasic cultivation strategy the process initially passes through a cell proliferation phase to generate a sufficiently high viable cell mass. In the subsequent production phase cells are maintained viable and productive without significant cell proliferation leading to increased viable cell days and product yields. In a previous work we have shown that the well directed alteration of the process environment based on process parameter shifting is a promising tool to regulate cell growth and protein expression. In continuation of this work we investigated process parameters which have been identified to affect cell proliferation in favor of an increased specific productivity and total product yield in a series of biphasic batch cultivation experiments. In most of these processes the integral of viable cells and the specific productivity were increased leading to a significant improvement of both final product concentration and volumetric productivity. In addition, combined parameter shifts (pH 6.90/30 degrees C and pH 6.90/33 degrees C) exerted a synergistic effect on product quality. The loss of product sialylation which occurred at reduced temperatures was prevented by simultaneously reducing the external pH. In conclusion, biphasic cultivation based on combined shifting of process parameters is a suitable tool for controlling cell proliferation and protein expression of mammalian cells in a batch bioreactor leading to enhanced volumetric productivities and therefore offers an enormous potential for bioprocess optimization.
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Affiliation(s)
- Evelyn Trummer
- Department of Biotechnology, Institute of Applied Microbiology, University of Natural Resources and Applied Life Sciences Vienna, Muthgasse 18, 1190 Vienna, Austria
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Harvey DJ. Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update covering the period 1999-2000. MASS SPECTROMETRY REVIEWS 2006; 25:595-662. [PMID: 16642463 DOI: 10.1002/mas.20080] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
This review describes the use of matrix-assisted laser desorption/ionization (MALDI) mass spectrometry for the analysis of carbohydrates and glycoconjugates and continues coverage of the field from the previous review published in 1999 (D. J. Harvey, Matrix-assisted laser desorption/ionization mass spectrometry of carbohydrates, 1999, Mass Spectrom Rev, 18:349-451) for the period 1999-2000. As MALDI mass spectrometry is acquiring the status of a mature technique in this field, there has been a greater emphasis on applications rather than to method development as opposed to the previous review. The present review covers applications to plant-derived carbohydrates, N- and O-linked glycans from glycoproteins, glycated proteins, mucins, glycosaminoglycans, bacterial glycolipids, glycosphingolipids, glycoglycerolipids and related compounds, and glycosides. Applications of MALDI mass spectrometry to the study of enzymes acting on carbohydrates (glycosyltransferases and glycosidases) and to the synthesis of carbohydrates, are also covered.
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Affiliation(s)
- David J Harvey
- Department of Biochemistry, Oxford Glycobiology Institute, University of Oxford, Oxford OX1 3QU, United Kingdom.
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Jeong DW, Cho IT, Kim TS, Bae GW, Kim IH, Kim IY. Effects of lactate dehydrogenase suppression and glycerol-3-phosphate dehydrogenase overexpression on cellular metabolism. Mol Cell Biochem 2006; 284:1-8. [PMID: 16477389 DOI: 10.1007/s11010-005-9004-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2005] [Accepted: 09/13/2005] [Indexed: 10/25/2022]
Abstract
In order to conduct a physiological functional study of lactate dehydrogenase (LDH) and glycerol-3-phosphate dehydrogenase (GPDH), we engineered a CHO dhfr(-) cell, by overexpressing either the anti-sense LDH-A RNA (anti-LDH cells) or GPDH (GP3 cells), or both (GP3/anti-LDH cells). LDH activity in the cell cytosol, and lactate content and pHe change in the growth media were found to decrease according to the order: cell lines GP3/anti-LDH > anti-LDH > GP3 > CHO. Intracellular ATP contents, representing the extent of respiration rate, also decreased, according to a rank order as follows: GP3 > CHO > GP3/anti-LDH > anti-LDH. We also attempted to identify and characterize any physiological changes occurring in the cells which harbored diverse metabolic pathways. First, anti-LDH cells with heightened respiration rates were found to display a higher degree of sensitivity to the prooxidant tert-butyl hydroperoxide (tBOOH), and the mitochondrial complex III inhibitor, antimycin A, than the GPDH-expressing cells (GP3 and GP3/anti-LDH), which have a lower respiration rate. Second, the anti-sense LDH-A RNA-expressing cells (anti-LDH and GP3/anti-LDH) evidenced a higher degree of resistance to apoptosis by cell-cell contact inhibition, and a faster doubling time ( approximately 19 h compared with approximately 26 h) than the CHO and GP3 cells. Additionally, cell growth in an extended culture under HCO(3) (-)-free conditions to induce a steep acidification could be maintained with the anti-sense LDH-A RNA-expressing cells, but could not be maintained with the CHO and GP3 cells. Third, we observed that the most appropriate cell line for the optical production of a certain therapeutic protein (Tissue-Plasminogen Activator) was the GP3/anti-LDH cells. Collectively, our data indicate a variety of physiological roles for LDH and GPDH, including cellular acidosis, oxidoresistance, apoptosis by both acidosis and cell-cell contact inhibition, cell growth, and the generation of recombinant proteins.
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6
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Trummer E, Fauland K, Seidinger S, Schriebl K, Lattenmayer C, Kunert R, Vorauer-Uhl K, Weik R, Borth N, Katinger H, Müller D. Process parameter shifting: Part I. Effect of DOT, pH, and temperature on the performance of Epo-Fc expressing CHO cells cultivated in controlled batch bioreactors. Biotechnol Bioeng 2006; 94:1033-44. [PMID: 16736530 DOI: 10.1002/bit.21013] [Citation(s) in RCA: 151] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The impact of process environment changes on process performance is one of the most crucial process safety issues when cultivating mammalian cells in a bioreactor. In contrast, directed shifting of process parameters can also be used as an optimization tool providing higher cell and product yields. Compared to other strategies that also aim on the regulation of cell growth and protein expression process parameter shifts can be easily performed without reagent addition or even genetic modification of the host cell line. However, a successful application of changing process conditions implies a profound understanding of the provoked physiological changes within the cells. In a systematic approach we varied the dissolved oxygen tension (DOT), pH, and temperature of CHO cultures in controlled bioreactors and investigated the impact on growth, productivity, metabolism, product quality and cell cycle distribution using a recombinant CHO cell line expressing the highly glycosylated fusion protein Epo-Fc. We found the reduction of cultivation temperature and the reduction of (external) pH to exert the most significant effects on process performance by mainly reducing cell growth and metabolism. With respect to the cell line used we identified a set of parameters capable of affecting cell proliferation in favor of an increased specific productivity and total product yield. The well directed alteration of the process environment has emerged as a tool adequate for further process optimization applying a biphasic cultivation strategy.
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Affiliation(s)
- Evelyn Trummer
- Department of Biotechnology, Institute of Applied Microbiology, University of Natural Resources and Applied Life Sciences Vienna, Muthgasse 18, 1190 Vienna, Austria
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7
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Sanchez-Bustamante CD, Kelm JM, Mitta B, Fussenegger M. Heterologous protein production capacity of mammalian cells cultivated as monolayers and microtissues. Biotechnol Bioeng 2005; 93:169-80. [PMID: 16255048 DOI: 10.1002/bit.20679] [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: 12/13/2022]
Abstract
A precise understanding of processes managing heterologous protein production in vitro and in vivo is essential for the manufacture of sophisticated biopharmaceuticals as well as for future gene therapy and tissue engineering initiatives. Capitalizing on the gravity-enforced self-assembly of monodispersed cells into coherent (multicellular) microtissues we studied heterologous protein production of microtissues and monolayers derived from cell lines and primary cells engineered/transduced for (i) constitutive, (ii) proliferation-controlled, (iii) macrolide-, or (iv) gas-inducible expression of the human placental secreted alkaline phosphatase (SEAP) and of the Bacillus stearothermophilus-derived secreted alpha-amylase (SAMY). Specific productivity of cells assembled in microtissues was up to 20-fold higher than isogenic monolayer cultures. Diffusion across microtissues could be further increased by HUVEC-mediated vascularization. As well as higher specific protein productivities, microtissues were also more efficient than monolayer cultures in assembling transgenic lentiviral particles. Our results showed that mammalian cells embedded in a tissue-like three-dimensional (3D) microenvironment exhibit increased production capacity. This observation should be considered for gene therapy and tissue engineering scenarios as well as for biopharmaceutical manufacturing.
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Affiliation(s)
- Carlota Diaz Sanchez-Bustamante
- Institute for Chemical and Bio-Engineering, ICB, Swiss Federal Institute of Technology, ETH Hoenggerberg, HCI F115, Wolfgang-Pauli-Strasse 10, CH-8093 Zurich, Switzerland
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8
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Bi JX, Shuttleworth J, Al-Rubeai M. Uncoupling of cell growth and proliferation results in enhancement of productivity in p21CIP1-arrested CHO cells. Biotechnol Bioeng 2004; 85:741-9. [PMID: 14991652 DOI: 10.1002/bit.20025] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Chinese hamster ovary cells have been engineered to inducibly over-express the p21(CIP1) cyclin-dependent kinase inhibitor, to achieve cell cycle arrest and increase cell productivity. In p21(CIP1)-arrested cells production of antibody from a stably integrated lgG4 gene, was enhanced approximately fourfold. The underlying physiological basis for enhanced productivity was investigated by measuring a range of cellular and metabolic parameters. Interestingly, the average cell volume of arrested cells was approximately fourfold greater than that of proliferating cells. This was accompanied by significant increases in mitochondrial mass, mitochondrial activity, and ribosomal protein S6 levels. Our results suggest that p21(CIP1)-induced cell cycle arrest uncouples cell growth from cell-cycle progression, and provides new insight into how improved productivity can be achieved in a cell line commonly used for large-scale production of pharmaceutical proteins.
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Affiliation(s)
- Jing-Xiu Bi
- Department of Chemical Engineering, University of Birmingham, Birmingham B15 2TT, United Kingdom
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9
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Metabolic engineering of mammalian cells for higher protein yield. ACTA ACUST UNITED AC 2003. [DOI: 10.1016/s0167-7306(03)38027-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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10
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Meents H, Enenkel B, Werner RG, Fussenegger M. p27Kip1-mediated controlled proliferation technology increases constitutive sICAM production in CHO-DUKX adapted for growth in suspension and serum-free media. Biotechnol Bioeng 2002; 79:619-27. [PMID: 12209809 DOI: 10.1002/bit.10322] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
We have engineered dihydrofolate reductase-deficient (dhfr(-)) Chinese hamster ovary (CHO)-DUKX B11 cells adapted for growth in serum-free suspension cultures for unlinked muristerone-inducible expression of the cyclin-dependent kinase inhibitor p27Kip1 and constitutive expression of the soluble intercellular adhesion molecule-1 (sICAM), a potent common cold therapeutic. Conditional overexpression of p27Kip1 resulted in a sustained G1-specific growth arrest of transgenic CHO-DUKX associated with up to fivefold-increased specific sICAM productivity. Herein we exemplify the implementation of controlled proliferation technology in a major biopharmaceutical production cell line that is compatible with key requirements for large-scale production procedures, including constitutive transgene expression and anchorage-independent growth in serum-free media.
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Affiliation(s)
- Heiko Meents
- Institute of Biotechnology, Swiss Federal Institute of Technology, ETH Zurich, CH-8093 Zurich
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11
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Affiliation(s)
- Martin Fussenegger
- Institute of Biotechnology, Swiss Federal Institute of Technology, ETH Zurich, Switzerland.
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12
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Schroeder K, Koschmieder S, Ottmann OG, Hoelzer D, Hauser H, Mueller PP. Coordination of cell growth in cocultures by a genetic proliferation control system. Biotechnol Bioeng 2002; 78:346-52. [PMID: 11920451 DOI: 10.1002/bit.10196] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Advanced cell culture systems such as organotypic cultures or stem cell expansion often involve cocultivation of two or more different cell types. A typical situation is the use of a feeder cell line that supports survival, growth or controls the differentiation status of primary cells. Unequal proliferation capacities result in unbalanced cell growth, such as the undesired expansion of immortalized cells at the expense of the primary cells. We utilized a genetic regulatory system to coordinate cell growth in cocultures. Proliferation control of a feeder cell line by a recombinant transcription factor was employed to prevent feeder cells from overgrowing cocultured stem cells, thereby avoiding premature media exhaustion. Relevant characteristic cell-surface proteins present on the parental feeder cell line were preserved. No special equipment was required and cell-type specific growth could be adjusted even during coculture. When compared to a conventional gamma-irradiation procedure, genetic proliferation control was superior with respect to ease of use, robustness, cell adherence, morphology and viability. The results demonstrate the applicability of genetic proliferation control to coordinate growth of different cell types in cocultures.
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Affiliation(s)
- Katharina Schroeder
- Department of Gene Regulation and Differentiation, German Research Center for Biotechnology, D-38124 Braunschweig, Germany
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13
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Irani N, Beccaria AJ, Wagner R. Expression of recombinant cytoplasmic yeast pyruvate carboxylase for the improvement of the production of human erythropoietin by recombinant BHK-21 cells. J Biotechnol 2002; 93:269-82. [PMID: 11755990 DOI: 10.1016/s0168-1656(01)00409-6] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Recently, a recombinant yeast pyruvate carboxylase expressed in the cytoplasm of BHK-21 cells was shown to reconstitute the missing link between glycolysis and TCA, thus increasing the flux of glucose into the TCA and resulting in a higher intracellular ATP content. Now, these metabolically engineered cells have been additionally transfected with a plasmid bearing the gene for human erythropoietin. EPO yield and substrate-specific productivity of the recombinant BHK-21 cells have been compared to control cells without the PYC2-gene but transfected with the plasmid coding for the expression of the selection genes and EPO. PYC2-expressing clones showed a 2-fold higher glucose-specific productivity and a 2-fold higher product concentration in a continuously perfused bioreactor. Moreover, the PYC2 expression enabled the cells to become more resistant to low glucose concentrations in the culture medium. They could produce at nearly maximum productivity under glucose-limiting conditions of 0.05-1 gl(-1) that guaranteed a reduced accumulation of lactate in fed-batch production systems. Due to the fact that PYC2-expressing cells are characterized by reduced glucose consumption, a prolonged production phase in bioreactors can be maintained. Based on the demand not to fall short of 80% cell viability for the production, EPO could be produced for 2 days (30%) longer compared to the control due to a more economic exploitation of glucose, and the prolonged viability period of the cells using a batch cultivation driven by glutamine limitation.
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Affiliation(s)
- Noushin Irani
- Department of Cell Culture Technology (ZKT), National Research Centre for Biotechnology (GBF), Mascheroder Weg 1, D-38124 Braunschweig, Germany
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14
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Carvalhal AV, Coroadinha A, Alves PM, Moreira JL, Hauser H, Carrondo MJ. Metabolic changes during cell growth inhibition by the IRF-1 system. Enzyme Microb Technol 2002. [DOI: 10.1016/s0141-0229(01)00460-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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15
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Skibeli V, Nissen-Lie G, Torjesen P. Sugar profiling proves that human serum erythropoietin differs from recombinant human erythropoietin. Blood 2001; 98:3626-34. [PMID: 11739166 DOI: 10.1182/blood.v98.13.3626] [Citation(s) in RCA: 160] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Erythropoietin (EPO) from sera obtained from anemic patients was successfully isolated using magnetic beads coated with a human EPO (hEPO)-specific antibody. Human serum EPO emerged as a broad band after sodium dodecyl sulfate-polyacrylamide gel electrophoresis, with an apparent molecular weight slightly smaller than that of recombinant hEPO (rhEPO). The bandwidth corresponded with microheterogeneity because of extensive glycosylation. Two-dimensional gel electrophoresis revealing several different glycoforms confirmed the heterogeneity of circulating hEPO. The immobilized anti-hEPO antibody was capable of binding a representative selection of rhEPO glycoforms. This was shown by comparing normal-phase high-performance liquid chromatography profiles of oligosaccharides released from rhEPO with oligosaccharides released from rhEPO after isolation with hEPO-specific magnetic beads. Charge analysis demonstrated that human serum EPO contained only mono-, di-, and tri-acidic oligosaccharides and lacked the tetra-acidic structures present in the glycans from rhEPO. Determination of charge state after treatment of human serum EPO with Arthrobacter ureafaciens sialidase showed that the acidity of the oligosaccharide structures was caused by sialic acids. The sugar profiles of human serum EPO, describing both neutral and charged sugar, appeared significantly different from the profiles of rhEPO. The detection of glycan structural discrepancies between human serum EPO and rhEPO by sugar profiling may be significant for diagnosing pathologic conditions, maintaining pharmaceutical quality control, and establishing a direct method to detect the misuse of rhEPO in sports.
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Affiliation(s)
- V Skibeli
- Section for Doping Analysis, Hormone Laboratory, Aker University Hospital, Oslo, Norway.
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16
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Schlatter S, Bailey JE, Fussenegger M. Novel surface tagging technology for selection of complex proliferation-controlled mammalian cell phenotypes. Biotechnol Bioeng 2001; 75:597-606. [PMID: 11745136 DOI: 10.1002/bit.1189] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Regulated overexpression of the cyclin dependent kinase inhibitor p27 enables biphasic production processes which consist of a nonproducing expansion phase followed by an extended proliferation-arrested production phase. During the growth-arrested production phase proliferation-competent mutants emerge as a consequence of genetic drift and strong counterselection. Here, we evaluate the use of cell surface markers for ex vivo selection of growth-arrested phenotypes by magnetic or FACS-mediated cell sorting. Multigene metabolic engineering resulted in a Chinese hamster ovary- (CHO) derived cell line CHO-SS101(5), which expresses the model product protein SEAP (secreted alkaline phosphatase), the human cyclindependent kinase inhibitor p27, and a membrane-anchored multidomain surface marker Hook in a tricistronic tetracycline-repressible manner. In the absence of tetracycline in the cell culture medium, p27 mediated a G1-phase-specific cell-cycle arrest of CHO-SS101(5) and resulted in a fivefold increase in SEAP production compared to proliferation-competent control cells. Concomitant expression of Hook enabled FACS- or magnetic-based selection of CHO-SS101(5) cells from various mixed populations. Surface selection of engineered cells will likely become important for biopharmaceutical manufacturing and for in vivo maintenance of treated cells in gene therapy and tissue engineering.
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Affiliation(s)
- S Schlatter
- Institute of Biotechnology, Swiss Federal Institute of Technology, ETH Zurich, CH-8093 Zurich, Switzerland
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17
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Kaufmann H, Mazur X, Marone R, Bailey JE, Fussenegger M. Comparative analysis of two controlled proliferation strategies regarding product quality, influence on tetracycline-regulated gene expression, and productivity. Biotechnol Bioeng 2001. [DOI: 10.1002/1097-0290(20010320)72:6<592::aid-bit1024>3.0.co;2-j] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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18
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Geserick C, Bonarius HP, Kongerslev L, Hauser H, Mueller PP. Enhanced productivity during controlled proliferation of BHK cells in continuously perfused bioreactors. Biotechnol Bioeng 2000; 69:266-74. [PMID: 10861406 DOI: 10.1002/1097-0290(20000805)69:3<266::aid-bit4>3.0.co;2-z] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
A perfused cell-culture process was developed to investigate the stability of IRF-1-mediated proliferation control in BHK cells and to evaluate the efficacy of a novel promoter in these cells. The cell density of proliferation-controlled producer cells was effectively regulated for over 7 weeks in a microcarrier-based continuously perfused bioreactor. An IRF-1-inducible promoter was employed to express a heterodimeric IgG antibody as a relevant model protein. Basal expression levels were equivalent to that of a highly active viral promoter, while productivity increased up to sixfold during growth arrest. However, no stably expressing clone was isolated in this study. Protein expression decreased gradually with time and could not be induced further in subsequent growth-repression cycles. The results demonstrate that the regulatory system is sufficiently stable to allow controlled growth in a continuous scalable reactor system and that productivity increases can be achieved in a proliferation controlled microcarrier culture.
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Affiliation(s)
- C Geserick
- Department of Gene Regulation and Differentiation, GBF, National Research Center for Biotechnology, Braunschweig, Germany
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