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Growth limitations in high density microcarrier cultures
Developments in Biological Standardization
|January 1, 1985
Summary
Cell growth in microcarrier cultures is limited by ammonia accumulation, not nutrient depletion. Perfusion systems increase cell density but ammonia still inhibits growth, suggesting it
Area of Science:
- Biotechnology
- Cell Culture Engineering
- Bioprocess Optimization
Background:
- Anchorage-dependent animal cells can be cultured on microcarriers as quasi-suspension cultures.
- This method allows for high cell density production, crucial for biopharmaceutical manufacturing.
Purpose of the Study:
- To investigate parameters limiting final cell yield in microcarrier cultures.
- To identify the specific limiting factor, whether nutrient depletion or growth inhibitor accumulation.
Main Methods:
- Analyzed amino acid utilization and nutrient depletion in batch and perfused MDCK and BHK cell cultures.
- Investigated the effect of glutamine concentration and ammonia accumulation on cell growth.
- Performed growth experiments with diluted culture media to differentiate between nutrient and inhibitor limitations.
Main Results:
- Glutamine is rapidly consumed, serving as a primary energy source.
- Ammonia accumulates in both batch and perfused cultures, reaching inhibitory levels (2.3-2.5 mM) that halt cell growth.
- Cell yield is not directly related to medium dilution, indicating inhibitor accumulation rather than nutrient depletion is the limiting factor.
Conclusions:
- Ammonia accumulation is identified as the primary growth inhibitor in microcarrier cell cultures.
- Optimizing glutamine levels and managing ammonia byproduct are critical for maximizing cell yields in these systems.