Cryopreservation

Cell lines in continuous culture are prone to genetic drift, finite cell lines are fated for senescence, all cell cultures are susceptible to microbial contamination and even the best-run laboratories can experience equipment failure. Because an established cell line is a valuable resource and its replacement is expensive and time consuming, it is vital that they are frozen and preserved for long-term storage.

The best method for cryopreserving cultured cells is storing them in liquid nitrogen in complete medium in the presence of a cryoprotective agent such as dimethylsulfoxide (DMSO). Cryoprotective agents reduce the freezing point of the medium and also allow a slower cooling rate (1 °C per minute), greatly reducing the risk of ice crystal formation, which can damage cells and cause cell death.

Remember to freeze your cultured cells at a high concentration and at as low a passage number as possible, make sure that the cells are at least 90% viable before freezing and always wear personal protective equipment.