Kimura R, Miller W M
Chemical Engineering Department, Northwestern University, Evanston, Illinois 60208-3120.
Biotechnol Bioeng. 1996 Oct 5;52(1):152-60. doi: 10.1002/(SICI)1097-0290(19961005)52:1<152::AID-BIT15>3.0.CO;2-Q.
Carbon dioxide is a by-product of mammalian cell metabolism that will build up in culture if it is not removed from the medium. Increased carbon dioxide levels are generally not a problem in bench-top bioreactors, but inhibitory levels can easily be reached in large-scale vessels, especially if the aeration gas is enriched in oxygen. Due to the equilibrium attained between dissolved CO(2) and bicarbonate, increased pCO(2) is associated with increased osmolality in bioreactors with pH control. While a few preliminary reports indicate that elevated pCO(2) levels can inhibit cell growth and/or recombinant protein production, no comprehensive analysis of the interrelated effects of elevated pCO(2) and osmolality has been published. We have examined the effects of 140, 195, and 250 mm Hg (187, 260, and 333 mbar, respectively) pCO(2) (with and without osmolality control) on the growth of and recombinant tPA production by MT2-1-8 Chinese hamster ovary (CHO) cells. The effects of elevated osmolality were also investigated at the control pCO(2) of 36 mm Hg. Elevated pCO(2) at 310 mOsm/kg osmolality inhibited cell growth in a dose-dependent fashion, with a maximum decrease of 30% in the specific growth rate (mu) at 250 mm Hg. Osmolality alone had no effect on mu, but the combination of elevated pCO(2) and osmolality increased the maximal reduction in mu to 45%. Elevated pCO(2) at 310 mOsm/kg osmolality decreased the specific tPA production rate (q(tPA)) by up to 40% at 250 mm Hg. Interestingly, while increased osmolality decreased q(tPA) significantly at 140 mm Hg pCO(2), it had no effect or even increased q(tPA) at 195 and 250 mm Hg. (c) 1996 John Wiley & Sons, Inc.
二氧化碳是哺乳动物细胞代谢的副产物，如果不从培养基中去除，它会在培养过程中积累。在台式生物反应器中，二氧化碳水平升高通常不是问题，但在大型容器中很容易达到抑制水平，特别是如果曝气气体富含氧气。由于溶解的二氧化碳和碳酸氢盐之间达到平衡，在具有pH控制的生物反应器中，pCO₂升高与渗透压增加有关。虽然一些初步报告表明，升高的pCO₂水平会抑制细胞生长和/或重组蛋白的产生，但尚未发表关于升高的pCO₂和渗透压的相互关联影响的全面分析。我们研究了140、195和250 mmHg（分别为187、260和333 mbar）的pCO₂（有和没有渗透压控制）对MT2-1-8中国仓鼠卵巢（CHO）细胞生长和重组tPA产生的影响。还在36 mmHg的对照pCO₂下研究了渗透压升高的影响。在310 mOsm/kg渗透压下，升高的pCO₂以剂量依赖的方式抑制细胞生长，在250 mmHg时比生长速率（μ）最大降低30%。单独的渗透压对μ没有影响，但升高的pCO₂和渗透压的组合使μ的最大降低增加到45%。在310 mOsm/kg渗透压下，升高的pCO₂在250 mmHg时使tPA的比生产率（q(tPA)）降低高达40%。有趣的是，虽然在140 mmHg pCO₂下渗透压升高显著降低q(tPA)，但在195和250 mmHg时它没有影响甚至增加q(tPA)。(c) 1996 John Wiley & Sons, Inc.
