Kinetic studies on hybridoma cells immobilized in fixed bed reactors

Pörtner, Ralf; Rössing, Sabine; Koop, Matthias; Lüdemann, Ines

doi:10.1002/(sici)1097-0290(19970805)55:3<535::aid-bit10>3.0.co;2-f

Cited by 22 publications

(5 citation statements)

References 36 publications

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“…The fixed-bed reactor setup consists of a 1 liter conditioning vessel and a 50 ml fixed-bed in which the cells are immobilized on porous glass beads (3 to 5 mm in diameter (Siran, Schott, Germany)), a carrier which proved to be particularly suitable for cultivation of suspendable cells such as transfectoma or hybridoma as well as for adherent cells including CHO-K1 (Sràmkovà et al, 1995;Lüdemann et al, 1996;Pörtner et al, 1997). The fixed-bed is integrated in the conditioning vessel which allows simultaneous temperature control and maintenance of both subsystems at 37 • C by electrical heating.…”

Section: Cultivations In the Fixed-bed Reactormentioning

confidence: 99%

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et al. 2000

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Using multicistronic expression technology we generated a stable Chinese hamster ovary (CHO) cell line (MG12) expressing a model secreted heterologous glycoprotein, the secreted form of the human placental alkaline phosphatase (SEAP), and bcl-2, best known as an apoptosis inhibitor, in a tetracycline-repressible dicistronic configuration. In batch cultivations in serum-containing medium, MG12 cells reached twice the final viable cell density when Bcl-2 was overexpressed (in the absence oftetracycline) compared to MG12 populations culturedunder tetracycline-containing conditions (bcl-2repressed). However, bcl-2-expressing MG12 cellsshowed no significant retardation of the decline phasecompared to batch cultures in which the dicistronicexpression unit was repressed.Genetic linkage of bcl-2 expression with the reporter protein SEAP in our multicistronic construct allowed online monitoring of Bcl-2 expression over an extended, multistage fixed-bed bioreactor cultivation. The cloned multicistronic expression unit proved to be stable over a 100 day bioreactor run. CHO MG12 cells in the fixed-bed reactor showed a drastic decrease in the release of DNA into the culture supernatant under conditions of reduced tetracycline (and hencederepressed SEAP and bcl-2 overexpression). This observation indicated enhanced robustness associated with bcl-2 overexpression, similar to recent findings for constitutive Bcl-2-overexpressing hybridoma cells under the same bioprocess conditions. These findings indicate, in these serum-containing CHO cell cultures, that overexpression of Bcl-2 results in desirable modifications in culture physiology.

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Section: Cultivations In the Fixed-bed Reactormentioning

confidence: 99%

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et al. 2000

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“…Single- and two-phase-flow, fixed-bed bioreactors are legion in biochemical processing, such as in the production of antibodies, animal cell culture, fermentation, alcohol production, stereoselective bioconversion, and resolution of racemates, − as well as in wastewater and gas-scrubbing biological treatments, e.g., filtration of sewage sludge through sand pack filters, removal of carbon disulfide, volatile organic compounds, chlorinated aliphatic hydrocarbons, etc. − A common shared feature is that, in many bioconversion processes, the characteristics of the liquid medium (or broth) may change drastically during operation. While at the beginning liquids are Newtonian and exhibit water-like viscosity, quite often biomass growth and/or products formation turn these liquids into non-Newtonian fluids .…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamic Models for Rheologically Complex Fluids in Co- and Countercurrent Gas−Liquid Packed-Bed Bioreactors

Iliuta

Larachi

2002

Ind. Eng. Chem. Res.

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Processes implying the flow of rheologically complex fluids simultaneously with a gas phase through packed beds are multitudinous in biochemical processing. Paradoxically, conceptual models relating the packed-bed bioreactor hydrodynamics to the rheological characteristics of the non-Newtonian fluids in play are virtually nonexistent in this particular area. An attempt has, therefore, been made with this contribution to fill in this gap by providing a series of hydrodynamic models for the prediction of pressure drop and liquid holdup in cocurrent and countercurrent two-phase flow through packed beds in the so-called film-flow conditions, i.e., trickle-flow, preloading, and near-loading zones. The class of slit models has been generalized by extending the modeling to yield-stress inelastic non-Newtonian fluids such as Herschel−Bulkley and Bingham plastic fluids and, as particular cases, to the Ostwald−De Waele and Newtonian fluids. Model asymptotic formulations have also been derived for Herschel−Bulkley fluids flowing downward with stagnant gas (pure trickle flow) to yield their liquid holdup under gravity-driven flows, as well as in single-phase-flow conditions to yield the single-phase frictional pressure drops. The response of these models to changes in yield stress, consistency and power-law index, and gas density, for both cocurrent downflow and countercurrent flow, reveals that non-Newtonian fluids behave qualitatively as their Newtonian homologues in terms of fluid throughputs, apparent viscosity, and gas density.

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“…As a result very high cell densities and product titres can be achieved in a relatively small bioreactor. A wide variety of intensive culture systems have been developed, including spin-filter perfusion bioreactors, dialysis systems, hollow fibre devices and fixed-bed reactors (Himmelfarb, 1969;Tharakan and Chau, 1986;Comer et al, 1990;Ong et al, 1994;Jan et al, 1992;Amos et al, 1994;Emery et al, 1995;Pörtner et al, 1997;Fassnacht et al, 1998b).…”

Section: Introductionmentioning

confidence: 99%

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et al. 1999

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Apoptosis is an active, genetically determined death mechanism which can be induced by a wide range of physiological factors and by mild stress. It is the predominant form of cell death during the production of antibodies from murine hybridoma cell lines. A number of studies have now demonstrated that the suppression of this death pathway, by means of over-expression of survival genes such as bcl-2, results in improved cellular robustness and antibody productivity during batch culture. In the present study, the influence of bcl-2 expression on hybridoma productivity in two high density perfusion bioreactor systems was investigated. In the first system, a fixed-bed reactor, the DNA content in the spent medium was 25% higher in the control (TB/C3-pEF) culture than that found in the bcl-2 transfected (TB/C3-bcl2) cultures at all perfusion rates. This is indicative of a higher level of cell death in the control cell line. The average antibody concentration for the TB/C3-pEF cell line was 14.9 mg L-1 at perfusion rates of 2.6 and 5.2 d-1. However, for the TB/C3-bcl2 cell line it was 33 mg L-1 at dilution rates of 2 and 4 d-1. A substantial increase in antibody concentration was also found in the Integra Tecnomouse hollow fibre reactor. The antibody titre in the TB/C3-bcl2 cassette was nearly 100% higher than that in the TB/C3-pEF cassette during the cultivation period which lasted 6 weeks. Clearly, these results demonstrate the positive impact of bcl-2 over-expression on production of antibody in hybridoma perfusion cultures.

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Kinetic studies on hybridoma cells immobilized in fixed bed reactors

Cited by 22 publications

References 36 publications

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Hydrodynamic Models for Rheologically Complex Fluids in Co- and Countercurrent Gas−Liquid Packed-Bed Bioreactors

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