5. Transfer cells immediately to -20°C for one hour, followed by -80°C overnight before permanent storage in liquid
nitrogen.
This step must be done as soon as the cells are in freezing media. DMSO and some other
cryoprotectants are toxic to cells and so should not be exposed to the cells at room temperature
for any longer than necessary. Thawing of the vials and placing of the cell suspension back into
culture media should also be done very quickly for the same reasons.
6. Thawing and recovery of cells from liquid nitrogen must be done quickly. Prepare pre-warmed medium in advance.
Remove cryovials from liquid nitrogen and immediately place in 37°C water bath and quickly shake until about 80% has thawed. This should not take more than a minute. Quickly pipette out into a flask, add the appropriate amount of medium and place in incubator.
7. After 24 hours, ensure cells are attached. Change culture media to remove non-adherent cells and replenish nutrients.
Changing the culture media will also remove any DMSO residues.