Basal medium	ActiCHO Feed A	ActiCHO Feed B	EfficientFeed A	FunctionMAX	Feed 1	Peak cell conc. [106 c/ml]	Harvest Titer [g/L]
ActiCHO P	daily; 3%	daily; 0.3%	-	-		23.9	5.48
ActiCHO P	daily; 3%	daily; 0.3%	-	3, 5, 7; 3.3%		21.3	5.82
CD OptiCHO	-	-	3, 5, 7, 9; 10%	-		5.8	0.72
CD OptiCHO	-	-	3, 5, 7; 10%	-		5.2	0.80
CD OptiCHO	-	-	3, 5, 7; 10%	3, 5, 7; 3.3%		6.3	1.74
CD OptiCHO	daily; 3%	daily; 0.3%	-	-		9.0	1.46
BalanCD CHO	-	-	-	-	1, 3, 5; 10%	7.1	1.30

The time [d] for feed addition and the feed volume in % of the culture volume are indicated. Feed start for the culture in BalanCD CHO was day 1, all other cultures were fed from day 3 on. Values for peak cell concentration and harvest titer are mean values of triplicate experiments.

In batch cultures the highest cell concentrations were obtained in ActiCHO P and BalanCD as shown in Figure 1. In ActiCHO P the cells initially grew with a slightly higher specific growth rate (data not shown) and therefore the maximum cell concentration was reached 3 days earlier than in BalanCD. In ProCHO 5, Cellvento CHO-100 and CD OptiCHO, cell concentrations of 4 × 10⁶ to 5 × 10⁶ cells/mL were reached. Although initially the growth was similar in all three media, the culture in ProCHO 5 was terminated on day 7 due to a viability below 60%. In the other two media the batch lasted for four days longer. In Ex-Cell CD CHO cells grew to 2.6 × 10⁶ cells/mL which was about 30% of the cell concentration reached in ActiCHO P. Finally in CD CHO and CD FortiCHO cells formed small aggregates and rather low concentrations of 2.5 × 10⁶ and 6.0 × 10⁵ cells/mL were obtained, respectively. Cell adaptation in CD FortiCHO during seven passages and addition of Anti-Clumping Agent (1:250) did not resolve the aggregation problem or improve cell growth (data not shown). The antibody production in the different cultures followed the same ranking as the cell growth (Figure 1). The highest titers were achieved in ActiCHO P and BalanCD CHO. In CD OptiCHO, Ex-Cell CD CHO and Cellvento CHO-100 product concentrations of about 500 mg/L were reached. The lowest titers were generated in ProCHO 5 and CD CHO with 380 mg/L and 330 mg/L, respectively. Fed-batch cultivations were then run in selected basal media with the respective feeds according to table 1. Again there was a strong correlation between cell concentration and antibody production. The highest cell and product concentrations were obtained in ActiCHO P (Table 1). Compared with the previous batch cultures, the cell concentrations were more than doubled and due to the extended process duration the titer was increased more than 6 fold, as shown in table 1. Feeding cultures in ActiCHO P with Feed A and B alone or additionally with FunctionMAX, altered the process only marginally. Supplementing the fed-batch only with ActiCHO Feeds A&B resulted in slightly higher cell concentrations and the process duration was reduced by 2 days (data not shown). A fed-batch culture in BalanCD medium and Feed 1 reached only 80% of the cell concentration achieved during the previous batch culture, however, feeding extended the process by five days and increased the antibody concentration by 60% compared with the previous batch culture to a final titer of 1.3 g/L (Table 1). Fed-batch cultures in CD OptiCHO achieved about 40% of the cell concentrations in ActiCHO P. Similar cell concentrations were reached when feeding cultures in CD OptiCHO with ActiCHO feeds A and B or EfficientFeed A, independent if the feed was added during 7 or 9 days or if additional feeding with FunctionMAX was performed (Table 1). However, the feeding had an impact on the product concentration. The lowest one was obtained when feeding cultures in CD OptiCHO with EfficientFeed A only. Further supplementation with FunctionMAX or feeding with ActiCHO Feed A&B substantially increased the product concentration (Table 1).