For many years, it has been possible to freeze various types of cells and defrost them after many months or years.
The problem with the frozen preservation of cells is the potential risk of damage to the cellular organelles which are necessary to enable the cell to develop further. This most frequently happens due to the development of ice crystals during the freezing process because the majority of the cell consists of water. Another possible disturbance is damage to the liquid flows due to osmosis gradients within the cell. The addition of cryoprotectants greatly reduces this risk.