INCREASE IN PRODUCTIVITY AND CELL DENSITY
Figure 5: Total Immunoglobulin (IgG) amount in batch and perfusion cultivations.
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We have compared the productivity of recombinant anti–EpCAM in the bioreactor system operating in batch and perfusion mode.
During the perfusion run, approximately 50 L of medium had been consumed, which was 10 times the amount that was used in batch
mode. The maximum viable cell concentration was increased by a factor of 10. The total IgG yield in the perfusion run was
5900 mg, which was approximately 30 times greater than in the batch mode, where the total amount was 205 mg (see Figure 5).
This illustrates that the perfusion system is perfectly suited for the fast production of high amounts of proteins such as
monoclonal antibodies.
CONCLUSIONS
The authors demonstrated that an easy to use, off-the-shelf, single-use, bench-top perfusion bioreactor is capable of producing
and supporting very high cell density cultures of up to 150 × 106 cells/mL. This approach can be applied to mediocre cell lines in order to quickly produce the amounts of recombinant proteins
typically required during drug discovery or early development (e.g., for high throughput screening, or early preclinical studies
in animals), and formulation development. Furthermore, this is a simple approach to improve the efficiency of seed production
in large scale production. A typical seed train for a 1000 L bioreactor consists of a 50 L and 200 L bioreactor applying a
dilution factor of 1:5 to 1:10 at maximum. Assuming an inoculum cell density of 5 × 105 cells/mL at 1000 L scale, which is equivalent to 5 × 1011 cells, this density can be achieved by approximately 20 L of a high cell density culture grown in a rocking-motion perfusion
bioreactor. Certain limitations of this technology could be expected in larger bag systems, such as 100 L or 200 L rocking
motion bags with integrated membranes for cell retention. The oxygen transfer rate in these systems is usually lower, and
the ratio of membrane surface area to culture volume can not be scaled in a linear fashion due to size restrictions. While
cell densities of 30-40 × 106 cells/mL have been reported for these larger scale rocking motion systems, it is likely that extreme high cell densities
as reported in this article may not be reached.
THORSTEN ADAMS* is product manager, single use bioreactors, UTE NOACK is head of process engineering, upstream technology, TANJA FRICK is in upstream technology, GERHARD GRELLER is director, upstream technology, and CHRISTEL FENGE is vice-president, marketing and product management, fermentation, all at Sartoius Stedim Biotech, Göttingen, Germany, Thorsten.Adams@Sartorius-Stedim.com
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