ABSTRACT
Micro-bioreactors appear frequently in today's biotechnology industry as screening and process development tools for cell culture applications. The micro-bioreactor's small volume allows for a high throughput, and when compared to other small-scale systems, such as microtiter plates, its measurement and control capabilities offer a much better insight into the bioprocess. Applikon's micro-Matrix is one of the micro-bioreactors that are commercially available today. The micro-Matrix system consists of shaken disposable 24 deep square well plates in which each well is controlled individually for pH, dissolved oxygen (DO), and temperature. Additionally, a feeding module supports automated additions of liquid to each well. This chapter describes how the micro-Matrix can be used for fed-batch cultivations of Chinese Hamster Ovary (CHO) cells.
Subject(s)
Batch Cell Culture Techniques/instrumentation , Bioreactors , Biotechnology/instrumentation , Animals , Batch Cell Culture Techniques/methods , Biotechnology/methods , CHO Cells , Cell Count , Cricetulus , Hydrogen-Ion Concentration , Oxygen , TemperatureABSTRACT
Aim: To investigate the impact of various feeding strategies on the growth and productivity of a GS-CHO cell line. Methods: Feed additions were conducted at fixed volumes or linked to a marker such as cell growth or metabolism and added as bolus or near-continuously using the automated feeding module of the micro-Matrix (Applikon). Results: The selected feeding regimens supported maximum viable cell densities of up to 1.9 × 107 cells ml-1 and final titers of up to 1.13 g l-1. Differences in growth and titer between feeding strategies were insignificant, with the exception of one feeding strategy. Conclusion: As the more complex feeding strategies did not create an advantage, the selection of a simple feeding strategy such as bolus or continuous addition of feed medium is preferred.
Subject(s)
Batch Cell Culture Techniques/methods , Animals , Automation/methods , CHO Cells , Cell Proliferation/physiology , Cells, Cultured , Cricetulus , Culture Media/metabolismABSTRACT
OBJECTIVES: Establish a method to indirectly measure evaporation in microwell-based cell culture systems and show that the proposed method allows compensating for liquid losses in fed-batch processes. RESULTS: A correlation between evaporation and the concentration of Na+ was found (R2 = 0.95) when using the 24-well-based miniature bioreactor system (micro-Matrix) for a batch culture with GS-CHO. Based on these results, a method was developed to counteract evaporation with periodic water additions based on measurements of the Na+ concentration. Implementation of this method resulted in a reduction of the relative liquid loss after 15 days of a fed-batch cultivation from 36.7 ± 6.7% without volume corrections to 6.9 ± 6.5% with volume corrections. CONCLUSION: A procedure was established to indirectly measure evaporation through a correlation with the level of Na+ ions in solution and deriving a simple formula to account for liquid losses.
