The supply of oxygen to submerged cultures of BHK 21 cells

Radlett, P. J.; Telling, R. C.; Whitside, J. P.; Maskell, M. A.

doi:10.1002/bit.260140312

Cited by 38 publications

(8 citation statements)

References 13 publications

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“…Early work on growing BHK cells suggested that the optimum level of dissolved oxygen was < 50% saturation (Radlett et al 1972) but that was probably because the reactor was unbaffled and sparged without the use of Pluronic F68 (see discussion below). More resent work indicates that the cultivation of mammalian cells generally can be undertaken satisfactorily from 5% to 100% of air saturation (Oh et al 1989).…”

Section: Mass Transfer Performance and Oxygen Demandmentioning

confidence: 99%

Reactor Engineering in Large Scale Animal Cell Culture

2006

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This article mainly addresses the issues associated with the engineering of large-scale free suspension culture in agitated bioreactors >10,000 L because they have become the system of choice industrially. It is particularly concerned with problems that become increasingly important as the scale increases. However, very few papers have been written that are actually based on such large-scale studies and the few that do rarely address any of the issues quantitatively. Hence, it is necessary very often to extrapolate from small-scale work and this review tries to pull the two types of study together. It is shown that 'shear sensitivity' due to agitation and bursting bubbles is no longer considered a major problem. Homogeneity becomes increasingly important with respect to pH and nutrients at the largest scale and sub-surface feeding is recommended despite 'cleaning in place' concerns. There are still major questions with cell retention/recycle systems at these scales, either because of fouling, of capacity or of potential and different 'shear sensitivity' questions. Fed-batch operation gives rise to cell densities that have led to the use of oxygen and enriched air to meet oxygen demands. This strategy, in turn, gives rise to a CO 2 evolution rate that impacts on pH control, pCO 2 and osmolality. These interactions are difficult to resolve but if higher sparge and agitation intensities could be used to achieve the necessary oxygen transfer, the problem would largely disappear. Thus, the perception of 'shear sensitivity' is still impacting on the development of animal cell culture at the commercial scale. Microcarrier culture is also briefly addressed. Finally, some recommendations for bioreactor configuration and operating strategy are given.

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Section: Mass Transfer Performance and Oxygen Demandmentioning

confidence: 99%

Reactor Engineering in Large Scale Animal Cell Culture

2006

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“…(ii) Radlett et al 35 measured the oxygen uptake rate (OUR) of BHK cells during a 4-L batch culture under nonoxygen-limiting conditions; OUR was 0.1 mM 0,/109 cellsh. To achieve 2 x lo6 cells ~m -~, a minimum K p of 1.5 h-' is required, higher than that measured for 500-cm3 Coming spinners at 25 rpm.2 (iii) Data from the literature also confirm this hypothesis: CHO, ST, and Vero cells were grown as microsphereinduced aggregates with sizes up to 400 p m and no growth limitation was r e p~r t e d '~; for tumor cells the thickness of the proliferative region was reported to range between 50 and 200 pm2'; thus aggregates up to 1OMOO p m are expected to have only proliferative cells.…”

Section: Effects Of Agitation On Cell Growth Viability and Productivitymentioning

confidence: 99%

Hydrodynamic effects on BHK cells grown as suspended natural aggregates

Moreira

Alves

Auniņš

et al. 1995

Biotech & Bioengineering

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Baby hamster kidney (BHK) cell aggregates grown in stirred vessels with different working volumes and impeller sizes were characterized. Using batch cultures, the range of agitation rates studied (25-100 rpm) led to aggregates with maximum sizes of 150 mum. Necrotic centers were not observed and cell specific productivity was independent of aggregate size. High cell viability was found for both single and adherent cells without an increase in cell death when agitation rate was increased. The increase in agitation rate affected aggregates by reducing their size and increasing their concentration and cell concentration in aggregates, while increasing the fraction of free cells in suspension. The experimental relationship between aggregate size and power dissipation rate per unit of mass was close to -1/4, suggesting a correlation with a critical turbulence microscale; this was independent of vessel scale and impeller geometry over the range investigated. Viscous stresses in the viscous dissipation subrange (below Kolmogoroff eddies) appear to be responsible for aggregate breakage. Under intense agitation BHK cells grown in the absence of microcarriers existed as aggregates without cell damage, whereas cells grown on the surface of microcarriers were largely reduced. This is a clear advantage for scaleup purposes if aggregates are used as a natural immobilization system in stirred vessels. (c) 1995 John Wiley & Sons, Inc.

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“…For spherical emulsion particles, L 3 = 1/3, and eq. (3) reduces to (4) The expressions developed for effective electrical conductivities in heterogeneous systems have been claimed to be applicable to the estimation of other important physical properties including thermal conductivities, dielectric constants, and magnetic permeabilities for reasons of mathematical analogy in describing the process controlled by these properties.26227 Similarly, they can be applied to the estimation of oxygen permeabilities in PFC emulsions. In this case, Keff and Kd in eqs.…”

Section: Theorymentioning

confidence: 99%

“…This effect can be theoretically simulated by using different values of Kd in eqs. (1) and (4). In Figure 3, values of relative oxygen permeability thus derived under the assumptions of no and infinite surfactant-film resistance to mass transfer through water/PFC interface, respectively, are plotted against the PFC volume fractions, up to 50% (V/V).…”

Section: Oxygen Permeabilitymentioning

confidence: 99%

Effect of the interfacial surfactant layer on oxygen transfer through the oil/water phase boundary in perfluorocarbon emulsions

Lee

Armiger

1991

Biotech & Bioengineering

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The effect of interfacial surfactant molecules on oxygen transfer through oil/water phase boundary has been studied in FlurO(2) (TM) emulsions, i.e., perfluorocarbon (PFC) emulsions developed as oxygen carriers in cell culture. Measurements of oxygen permeability were made with a polarographic oxygen electrode in pure PFCs and in emulsions with various PFC volume fractions. Comparison of the experimental results with the theoretically derived values of relative oxygen permeability clearly indicates that the mass transfer resistance caused by the interfacial surfactant layer in PFC emulsions is insignificant. Therefore, oxygen dissolved in the enclosed PFC phase is readily available to cells growing in the aqueous media and FlurO(2) emulsions with very fine emulsion particles (< 0.2 microm) can be used to effectively enhance gas/liquid interfacial oxygen transfer in bioreactors. The inadequacy in describing mass transfer in heterogeneous systems, such as the PFC emulsions, by conventional concentration-based oxygen diffusion coefficients has also been discussed.

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The supply of oxygen to submerged cultures of BHK 21 cells

Cited by 38 publications

References 13 publications

Reactor Engineering in Large Scale Animal Cell Culture

Reactor Engineering in Large Scale Animal Cell Culture

Hydrodynamic effects on BHK cells grown as suspended natural aggregates

Effect of the interfacial surfactant layer on oxygen transfer through the oil/water phase boundary in perfluorocarbon emulsions

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