We are having trouble determining the optimal cell density for our transient expression in CHO. Any suggestions?

Answer

The optimal cell density is dependent upon a number of factors, but in a typical system comprising cells, media and transfection reagent, most often 1×10^6 cells/mL is the cell density chosen for a number of reasons: 1) Typical transfection reagents do not work well at very high cell densities—this is both a consequence of the transfection reagent itself as well as how well the culture media can maintain the high level of cell health at higher densities needed for high efficiency transfection, 2) at high transfection densities, cells will rapidly overgrow the cultures post transfection and unless your culture media can handle this, the culture will crash and productivity will be poor. The ExpiCHO transient expression system is designed to deal with all of these problems and has been developed to transfect CHO cells at 6×10^6 cells/mL, or even higher, densities significantly higher than the standard 1×10^6 cells/mL transfections that are typical. ExpiCHO utilizes this high cell density to increase the number of cells expressing your protein and to ensure maximal yields.