Improving Protein Production in CHO Cells - Biopharmaceutical protein manufacture can benefit from using chemically defined feeds in CHO cell lines. - BioPharm International
To determine the effects different feeds had on cell numbers and protein expression, a 15-L stir-tank bioreactor (Applikon
Biotechnology, Foster City, CA) containing CD CHO medium was inoculated with a different proprietary recombinant IgG CHO cell
line at 3 x 105 cells/mL. The pH and dissolved oxygen were set at 6.9 and 50%, respectively, with agitation at 150–175 rpm. The CO2 and oxygen sparge rates were both set at 100 mL/minute. Glucose was added to 6 g/L if the concentration in the media in the
bioreactor fell to less than 2 g/L. GS-Max (HyClone, Logan, UT) was fed at 1% of starting volume if the level of glutamate
fell to less than 1.5 mM, as occurred in all bioreactors. Four different feed strategies were carried out over 10 days. In
one bioreactor (Figure 3), 3% v/v addition of soy hydrolysate was added from a stock of 40 g/L every day for 10 days. In another
bioreactor (Figure 4), a 3% v/v solution of chemically defined feed A, (CHO CD EfficientFeed A) was added on days 0–5 followed
by addition on days 6–10 of daily supplementation of a 3% v/v solution of chemically defined feed B, (CHO CD EfficientFeed
B). The additional two feed strategies determined the effects of higher concentrations of the chemically defined feeds but
at fewer time points: 1) a 10% v/v solution of chemically defined feed A was added on days 0 and 3, followed by a 10% v/v
solution of chemically defined feed B on days 6, 9, and 2) a 15% v/v solution of feed A was added on day 0 followed by addition
of a 15% v/v solution of feed B on day 6. Both total cell counts and protein titers, as determined by ELISA over 13 days,
are presented in the results (Figures 3 and 4).
