Hello,
In our lab we produce a protein recombinantly using CHO-K1 cells. Therefore, these are first grown in adherent culture, then adapted to 200 mL suspension, after 2 days expanded to 400 mL suspension (without centrifugation) and then 2 days later to 1L suspension medium (with centrifugation) (all at 37 °C, without CO2). Then, after 2 days, we add 2 mM L-glut and 1% NaPy and put the temperature to 31°C. Finally after 4-5 days, we see cell count decreasing and we harvest our suspension medium.
Since this year we experience problems with this system (last year we had no problems at all). Our cell count drop drastically when going from 400 mL to 1L. We have tested everything up to this point and nothing works: we replaced all our medium components, H2O in which we dissolve medium, medium containers,...
Someone also had this problem recently or knows how to solve this?
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