Design of Experiment in CHO and HEK transient transfection condition optimization

Effect of addition of ‘carrier’ DNA during transient protein expression in suspension CHO culture

“…We found no significant trend in the protein expression levels when transfections were carried out over 110 generations, at 1.3 mg/l branched PEI concentration. A recent report (Bollin et al 2011) also has shown no difference in antibody titers at 1.5 mg/l linear PEI concentration at 4 and 70 passages, with no data reported in between. The number of cell generations corresponding to 70 passages by Bollin et al (2011) cannot be calculated from that report, but the general trend in this study is consistent with those results.…”

“…A recent report (Bollin et al 2011) also has shown no difference in antibody titers at 1.5 mg/l linear PEI concentration at 4 and 70 passages, with no data reported in between. The number of cell generations corresponding to 70 passages by Bollin et al (2011) cannot be calculated from that report, but the general trend in this study is consistent with those results. Bollin et al report a decrease in expression at higher linear PEI concentrations, but this was not evaluated in our study due to higher toxicity of branched PEI at higher N:P ratios.…”

“…Another cause of the variability could be differences in cell cycle distribution (Männistö et al 2005) which can affect DNA uptake. A third factor affecting protein expression could be the age of the culture (Bollin et al 2011). Transfection efficiency and protein expression also depend on the cell density at the time of transfection (Backliwal et al 2008;Sun et al 2008).…”

“…The plasmid DNA concentration has an 'interaction' with cell density. For instance, Bollin et al (2011), observed an increase in protein expression with increasing DNA concentrations during transfections using linear PEI at high cell densities.…”

Structural Biology of Glycoproteins

“…Transient transfection is attractive due to the short timeframe between transfection and purified protein. Glycoprotein yields for non-antibodies of up to 40 mg/L have been obtained from attached HEK cells [39] and 36 mg/L from HEK cells in suspension [40], with yields of 27 mg/L from CHO cells in suspension [40].…”