Cell Culture Condition Optimization
Based on the results obtained with Mix #25, the customer elected to pursue further increases in performance through optimization
of culture parameters rather than additional optimization of the medium. First, the culture temperature was shifted from 37
°C to 31 °C on cell culture day six, a point at which the rate of cell growth had decreased such that the viable cell density
increased <50% from the previous day. Examination of the growth profile of CL1 cultured in Mix #25 or CM1 control medium subject
to culture temperature shift (Figure 5A) illustrates that the low temperature significantly extends cell growth with minimum
influence on the maximum viable cell density to both control and optimized medium. Metabolite analysis showed that there was
no concentration difference between the high temperature and low temperature with the tested metabolites with the exception
of D-Glucose. Culture in both Mix #25 and CM1 with temperature shift had much lower rates of D-Glucose consumption than those
in the normal temperature (Figure 5B). For example, the D-Glucose level on day nine in cultures at 31 °C were about 10-fold
higher than cultures at 37 °C (Figure 5B, inset). This finding strongly suggests that the lower rate of D-Glucose consumption
might be associated with the improved cell growth.
To confirm the positive effect of higher levels of D-Glucose, glucose feeding and temperature shift were performed on CL1
cells in Mix #25. As expected, D-Glucose feeding significantly extended cell growth and the combination of D-Glucose feeding
and low temperature shift together further extended the cell growth at least seven days longer compared to the control condition
(Figure 5C). Analysis of IgG productivity showed that D-Glucose feeding or low temperature also improved the IgG production
compared to control conditions, and the combination of the D-Glucose feeding and temperature shift further improved the maximum
IgG production by >30%, from ~800 mg/L to ~1,100 mg/L (Figure 5D).
A new cell culture medium development platform, using the high-throughput screening, diverse selections of CHO cell culture
media formulations (CHO Media Library), cell line engineering, and DOE experimental design has been introduced to accentuate
medium development. Compared to traditional medium development approaches, this platform dramatically reduces costs and development
time (usually less than five months). Additionally, in this study the concept of a four-component DOE mixing analysis (pyramid
model) provides a more informative and efficient approach than conventional three-component DOE analysis (triangle model).
Using an IgG-producing CHO clone (CL1), this new strategic platform was used to develop a well-performing formulation supporting
increased IgG production from ~400 mg/L to 800 mg/L (~100%). Optimization of the cell culture conditions (low-temperature
shift and D-Glucose feeding) further improved IgG productivity by an additional 30%, further demonstrating the efficacy of
The authors would like to thank Mark Angeles, from Sigma-Aldrich Analytical R&D, for IgG sample analysis. We also kindly acknowledge
Mark Tizzard, Mason Williams, and Susan Bridges, from SAFC Biosciences, for their review of the manuscript and informative
Min Zhang is a senior scientist, Avril Lawshé is a scientist, Kerry Koskie is an associate scientist, Terrell Johnson is a principal scientist, Matthew V. Caple is the director, and James S. Ross is an R&D manager, all at Cell Sciences & Development, SAFC Biosciences, St. Louis, MO, 314.771.5765, ext. 3390, firstname.lastname@example.org
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