Facing the Challenges in Vaccine Upstream Bioprocessing - 33

Facing the Challenges in Vaccine Upstream Bioprocessing * Vero Perfusion, Packed-Bed Vessels Intensify Vaccine Production

Results
Confirming Cell Attachment

A

B

To assess Vero cell attachment on the Fibra-Cel
disks, we took a culture sample 30 minutes after
inoculation. No cells were observed in suspension,
indicating that the Vero cells had attached to the
Fibra-Cel disks rapidly. We started the perfusion on
day 3, because the glucose level became low and
the concentration of the toxic byproducts lactate
and ammonium increased.

Tracking Glucose Consumption
Using an indirect measure of cell growth, we
tracked the glucose consumption rate of the
culture (Figure 2A). We calculated the total glucose
consumption of the culture and the daily glucose
consumption rate.
For the first four days, the daily glucose consumption rates were around 2.7 g/day, indicating that
cells were in lag phase. From day 5, the glucose
consumption rate started to increase to 4.4 g/
day, and even doubled to 9.7 g/day on day 6, indi33

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Figure 2. (A) Daily glucose consumption rate of the culture. (B) Calculated Vero cell growth curve.
cating that cell growth had entered the log phase.
Cells were growing continuously, and the glucose
consumption rate doubled again to 19.4 g/day
on day 17. On the last day of the run, the glucose
consumption rate was still increasing, reaching
22.4 g/day. In total, the cells consumed 273 g
glucose during the 21 days.

disk sample, the average cell count was 4.43 × 106
cells. From this number, we extrapolated the total
number of cells in the culture as described previously.2 As a result, the total number of Vero cells in
the BioBLU 5p vessel at the end of the perfusion
culture was calculated as 1.51 × 1011 cells. The final
cell density at the end of the culture, based on the
3.5-L working volume, was 4.31 × 107 cells/mL.

Calculating Vero Cell Growth Curve
At the end of the process, we determined the cell
number by counting nuclei. For one Fibra-Cel

Based on the cell density at the end of the culture
(4.31 × 107 cells/mL) and the glucose consumption

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Facing the Challenges in Vaccine Upstream Bioprocessing

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