Cultured cells were collected upon reaching cell confluence and cell viability was measured based on trypan blue staining method. The cells were then resuspended in freezing medium composed of 90% complete culture medium II and 10% DMSO (Sigma, D2650-100ML) to reach a final concentration of 2.0 × 10 6 viable cells/mL. Division of cell suspension into cryogenic vials was performed with each vial containing 1 mL in total. The cryogenic vials were kept in a Nalgene Cryo 1°C Freezing Container (Thermo Scientific, 5100-0001) in a -80℃ refrigerator overnight, after which they were stored in liquid nitrogen for long.
Recovery of the frozen cells was conducted in the water bath at 37℃ quickly and warmup was completed when little ice in the cryogenic vials could be observed. The thawing cells were re-evaluated regarding its viability and then resuspended in fresh complete culture medium II for subsequent culture as mentioned above.
Recovery of the frozen cells was conducted in the water bath at 37℃ quickly and warmup was completed when little ice in the cryogenic vials could be observed. The thawing cells were re-evaluated regarding its viability and then resuspended in fresh complete culture medium II for subsequent culture as mentioned above.