Method of culturing eukaryotic cells

Abstract

An apparatus and method to maintain pH within a range conducive for cell growth in a bicarbonate-containing cell culture system without the addition of base. The method relies on the gas transfer characteristics of the bioreactor system to modulate the CO2 transfer to and from the cell culture such that the pH of the cell culture can be maintained within a desired range.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application claims benefit of U.S. Provisional Application No. 61 / 223,313, filed Jul. 6, 2009, the content of which is incorporated by reference herein in its entirety.FIELD OF THE INVENTION[0002]The invention relates to an apparatus and method for culturing eukaryotic cells in a bicarbonate-containing medium that allows maintenance of pH of the cell culture without the addition of bases directly to the culture medium.BACKGROUND OF THE INVENTION[0003]The culturing of cells for cell banking, for production of cell products, such as recombinant protein production is hampered by changing conditions as cells grow. While stainless steel bioreactors are often used for cell production, disposables are increasingly used at all stages in biologics manufacturing (Rao et al., 2009). In upstream processing, disposable bioreactors offer many advantages over their stainless steel counterparts (ranging from reducing cross-contamination risks to cost...

AI Technical Summary

Benefits of technology

The invention provides a method and apparatus for maintaining pH in a cell culture system without adding base. This is achieved by adjusting the amount of CO2 in the system using a dynamic interface between the liquid and gas phases in the culture system. The method involves adding or removing CO2 from the system by manipulating the gas phase in the headspace of the system. The invention allows for the modulation of pH without the need for additional gases or strong acids or bases. The invention can be performed in a vessel with agitation, such as rocking or shaking, to create a dynamic interface between the liquid and gas phases. The invention can be used with eukaryotic cells, such as vertebrate cells, and can be performed in rigid or pliable walls containers. The invention provides a simple and effective way to maintain pH in cell culture systems.

Problems solved by technology

The culturing of cells for cell banking, for production of cell products, such as recombinant protein production is hampered by changing conditions as cells grow.

However, the additional devices required, as well as the need for specially-designed bags to accommodate the pH and DO probes, increase the operational cost and complexity of this system.

In addition, the base addition required to raise culture pH to the defined setpoint in pH-controlled bioreactors increases the culture osmolality.

In addition, if the pH probe malfunctions, the resulting pH perturbations may alter cell metabolism and promote cell death (Miller et al., 1988; Osman et al., 2002).

However, pH and DO extremes are detrimental to cell growth and viability (Lin et al., 1993; Link et al., 2004; Miller et al., 1988; Osman et al., 2001), and may affect product quality (Restelli et al., 2006; Yoon et al., 2005).

The added features of conventional bioreactors such as real-time pH monitors and DO monitoring control add significantly to the cost and labor-intensity of cell culture in biological manufacturing.

Further, the failure or malfunction of these features can cause unacceptable variations and potential loss of the cell culture which is very costly in time and resources.

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