The tortoise or the hare? Accelerating freezing and thawing

The freezing of living cells and their survival after thawing developed into a discipline that we call cryobiology. The idea of freezing cells at low temperature was to serve the purpose of storing living cells indefinitely in a state of suspended animation, meaning that no ageing, metabolism or alteration of those cells would occur. The challenge for all scientists was to find protocols that would secure survival during exposure and storage at low temperatures, and subsequently return the cells to physiological conditions and environments. A critical factor was the concern that ice crystals can freeze intracellularly. This can occur if cells are cooled too rapidly, without an osmotically sufficient removal of water to eliminate supercooling. In the 1990s and at the start of the 2000s, two cryopreservation strategies ruled the field of cryobiology: traditional slow freezing protocols and vitrification protocols. Today, vitrification protocols dominate the cryopreservation of living cells, with a continued acceleration in the improvement of vitrification and warming protocols.