Chinese Hamster Ovary (CHO) cells are a popular workhorse for production of recombinant therapeutic proteins. Amenable to both adherent and suspension culture, CHO cells offer versatility in growth platform that is favorable to the end user’s requirements. See Table 1 for factors that differentiate cultures in adherent versus suspension platforms.
Table 1. Factors Differentiating Adherent versus Suspension CHO Cell Cultures
|Simple media changes
|Media change through perfusion or after pelleting / diluting cells
|Ease of use at small scale
|Ease of use at large scale
|Growth limited by surface area
|Growth independent of substrate / higher densities possible
|Cells must be dissociated for maintenance / scale up
|Cells do not require dissociation
|Often requires serum in media
|Often can be grown without serum
So why the switch? Simply put, growing CHO cells in suspension will allow for more manageable cell culturing at larger scales and ease in harvesting, which ultimately results in higher yields.
Antibody Yield of Suspension-adapted CHO-K1 Cells Equals That of Commercial Suspension CHO Cell Line. Human IgG antibody was produced by transient transfection with TransIT-PRO® Transfection Reagent (Mirus Bio) at a 1:1 reagent-to-DNA ratio (vol:wt) and 1 µg plasmid DNA per milliliter of culture in FreeStyle™ CHO-S cells (Thermo Fisher Scientific) and in-house suspension-adapted CHO-K1 cells cultured in CHOgro® Expression Medium (Mirus Bio) containing 4 mM L-Glutamine and 0.3% (vol:vol) Poloxamer 188 at a cell density of 4×106 cells/ml and grown at 37°C. All cells were split into non-tissue culture treated 6-well plates at the time of transfection. Day 7 and 14 supernatants were analyzed using a standard sandwich human IgG ELISA. Error bars represent standard deviation.
Adapt Cells to Suspension Growth in Serum-Containing Media
Reduce the Serum Percentage Slowly by Adaption to CHOgro® Expression Medium
Table 2. Stepwise Adaptation Schematic
|Basal Media with FBS and Poloxamer 188
|Complete CHOgro® Expression Medium
Only increase the percentage of target medium when cells are exhibiting normal doubling time and viability is > 95%. Once cells are fully adapted to complete CHOgro® Expression Medium, adjust to growth in 8% CO2 if desired.
3. Cryogenically bank the cells that have been suspension-adapted to serum-free media at 1×106 cells/ml.
Adapting adherent cells to suspension is a straightforward procedure that provides an alternative to purchasing commercially available cell lines. Implementing the use of suspension-adapted cells can expand growth and harvest workflows while simplifying the culturing process.
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