FREEZING CELLS GROWN IN SUSPENSION CULTURE

Freezing cells from suspension culture is similar in principle to freezing cells from monolayer. The major difference is that suspension cultures need not be trypsinized.
1. Transfer cell suspension to a centrifuge tube and spin 10 min at 300 to 350 × g (∼1500 rpm in Fisher Centrific centrifuge), room temperature.
2. Remove supernatant and resuspend pellet in 4°C freezing medium at a density of 106 to 107 cells/ml.
Some laboratories freeze lymphoblastoid lines at the higher cell density because they plan to recover them in a larger volume of medium and because there may be a greater loss of cell viability upon recovery as compared to other types of cells (e.g., fibroblasts).
3. Transfer 1-ml aliquots of cell suspension into cryovials and freeze as for monolayer