ThermoFisherScientific_Jan2021_ADeepDiveInto - 15

A Deep Dive into Perfusion Media for Bioprocessing Applications

* HIP CHO Medium at 1.2 VVD and TFF to retain the cells
and product in the reactor
* Fed-batch medium and 2X Gibco™ EfficientFeed™ C+
supplement
* A simple-batch (glucose-only) operation using the
original process medium as a control
During the concentrated fed-batch perfusion run, the
cell line achieved greater than 120 million viable cells/
mL, compared to a peak of 20-25 million viable cells/mL
in the simple-batch and fed-batch conditions (Figure 2,
on the preceeding page).
The fed-batch condition displayed a large increase in
productivity compared to the simple-batch condition,
achieving a >5-fold increase in titer.
Additionally, HIP CHO Medium further intensified the
productivity over the fed-batch condition nearly 2-fold.
When combined with the notably increased cell density,

Because a " batch-like " perfusion
operation happens in a shorter
length of time (commonly 14 to
20 days), it is important to reach
high VCD quickly while avoiding a
sharp crash immediately following
peak VCD.

this resulted in a >41-fold increase in titer. Further, at this
product concentration, a downstream concentrating
step was no longer required.
Because a " batch-like " perfusion operation happens in
a shorter length of time (commonly 14 to 20 days), it is
important to reach high VCD quickly while avoiding a
sharp crash immediately following peak VCD. Achieving
a balance of high initial log growth rate, peaking " gently " ,
and maintaining productivity are important. Your
medium should support a higher concentration, but
also allow targeted restrictions to prevent an excessively
high peak VCD, which will risk triggering a sharp crash.
In this case glucose was restricted at peak VCD to limit
further cell growth while maintaining high production and preventing a crash in maintained cells. This
approach allowed a high growth rate with a controlled
VCD limit to prevent the cell mass from depleting all
nutrients.

For continuous perfusion, the primary goal of a
medium is to sustain the culture and production
at a steady state. A common misconception
is that the cell growth rate must be reduced
to limit bleed. Cell bleed ultimately is used to
maintain a target quality profile, which generally
correlates to maintaining a percent cell viability.
So the true goal of a continuous perfusion
medium is to minimize the cell death rate of
a sustained cell line. This allows continuous
operation at a higher VCD and lower percent
bleed. Additionally, it is critical that a continuous
perfusion medium sustains productivity over
time. This means that steady-state metabolites
can continue to facilitate production, and the
formulation has no components that can build
up in cells and risk productivity loss over time.

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ThermoFisherScientific_Jan2021_ADeepDiveInto

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