Effect of Viscosity upon Hydrodynamically Controlled Natural Aggregates of Animal Cells Grown in Stirred Vessels

Authors

  • José L. Moreira,

    1. Instituto de Biologia Experimental e Tecnológica and Instituto de Tecnologia Química e Biológica, Apartado 12, P-2780 Oeiras, Portugal
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  • Paula C. Santana,

    1. Instituto de Biologia Experimental e Tecnológica and Instituto de Tecnologia Química e Biológica, Apartado 12, P-2780 Oeiras, Portugal
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  • Ana S. Feliciano,

    1. Instituto de Biologia Experimental e Tecnológica and Instituto de Tecnologia Química e Biológica, Apartado 12, P-2780 Oeiras, Portugal
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  • Pedro E. Cruz,

    1. Instituto de Biologia Experimental e Tecnológica and Instituto de Tecnologia Química e Biológica, Apartado 12, P-2780 Oeiras, Portugal
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  • Andrew J. Racher,

    1. Research Division, CAMR, Porton Down, Salisbury, Wiltshire SP4 0JG, U.K.
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  • J. Bryan Griffiths,

    1. Research Division, CAMR, Porton Down, Salisbury, Wiltshire SP4 0JG, U.K.
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  • Manuel J. T. Carrondo

    Corresponding author
    1. Instituto de Biologia Experimental e Tecnológica and Instituto de Tecnologia Química e Biológica, Apartado 12, P-2780 Oeiras, Portugal
    2. Laboratório de Engenharia Bioquímica, Faculdade de Ciěncias e Tecnologia, Universidade Nova de Lisboa, P-2825 Monte da Caparica, Portugal
    • Instituto de Biologia Experimental e Tecnológica and Instituto de Tecnologia Química e Biológica, Apartado 12, P-2780 Oeiras, Portugal
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Abstract

The effect of medium viscosity upon cell growth and aggregate characteristics of baby hamster kidney (BHK) cells cultivated in stirred tanks was evaluated. Two thickening agents were tested, 9300 MW dextran and a low-viscosity sodium (carboxymethyl)-cellulose; both were used in two different sets of experiments: (i) 250 cm3 Wheaton spinner flasks with a ball impeller operated at 45 rpm; (ii) 500 cm3 Corning spinner flasks with a paddle impeller, operated at constant power dissipation (88 cm2 s−3) Aggregate diameter and the fraction of cells in aggregates increased with the increase in viscosity. Power laws were applied to the experimental results. A dependence of aggregate size upon power dissipation of the order of –0.19 and kinematic viscosity of 0.34 and 0.49 for the constant agitation and constant power dissipation tests were obtained, respectively. A model based upon the entire universal-equilibrium range (i.e., the entire spectrum of isotropic eddies) was used to predict theoretical relationships between the variables studied. The model leads to a power dependence of –0.25 for the energy dissipated in the entire universal-equilibrium range and between 0.25 and 0.5 for the kinematic viscosity in the viscous dissipation subrange, depending on the energy correlation used; it also gives a good explanation for the dependence of aggregate size on the hydrodynamics of the vessel.

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