55
FAQ Sections
Use cell strainer whenever
clumping is observed
Seed two shaker flasks at 4 x 10
5
viable cells/mL
1 – 30P/500M
2 – 50P/1,000M
Check pools every 3-4 days: Is viability ≥90%
(and at least 1 additional passage past seeding)?
YES YES
NO NO
Each time cells are handled, if clumping is observed, strain cells before counting.
Check pool every 3-4 days.
Drugs 30P/500M 50P/1,000M
Puromycin 3 L/mL 5 L/mL
MTX (1 mM stock) 0.5 L/mL 1 L/mL
• Freeze at least 5 vials.
• Perform productivity
assessment.
Is VCD > 3 x 10
5
viable cells/mL
(or > 4 x 10
5
viable cells/mL at first pass)?
Centrifuge cells and perform a
complete medium exchange,
seeding cells at 3 x 10
5
viable
cells/mL (reduce volume if
needed), add drugs based on
volume fresh medium
Is VCD ≥ 6 x 10
5
viable cells/mL?
Were cells passaged at last sampling?
NO NO NO NO
Leave as-is
YES YES
YES YES
YES YES
Passage cells at 3 x 10
5
viable
cells/mL, add drugs based
on volume fresh medium
NO NO
Phase
II
Selection
Figure 10. Freedom
®
CHO-S
®
Phase II selection flowchart.
Life Technologies
™
| Freedom
®
CHO-S
®
Kit FAQ
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