What is Vitrification?

1) Living tissue is mostly made of water:


2) Water is part of a solution with other molecules in living things:


3) When tissue is cooled below freezing, water molecules gather together and form growing ice crystals:


4) Ice squeezes other molecules into a harmful concentrated solution:


5) On a cellular scale, ice forms first outside cells:


6) Growing ice causes cells to dehydrate and shrink:


7) Finally cells are left damaged and squashed between ice crystals:


8) Adding chemicals called cryoprotectants to water can prevent water molecules from gathering together to form ice:


9) Instead of freezing, molecules just move slower and slower as they are cooled:


10) Finally, at temperatures below -100° C, molecules become locked in place and a solid is formed. Water that becomes solid without freezing is said to be "vitrified":


11) Cryoprotectants are added to cells before deep cooling:


12) There is no damage to cells during cooling because no ice is formed:


13) Finally cells are vitrified and biological time is stopped:


14) Because no ice is formed, vitrification can solidify tissue without structural damage:


15) Entire organs can be solidified and stored at temperatures as low as -140° C. Scientists are working on ways to reduce the toxicity of the cryoprotectants used to make water vitrify to allow banking of organs for transplantation. At Alcor, we are optimistic that the toxicity that still does occur with vitrification of human organs will be reversible with future molecular repair technology.


For further general information about cryobiology, see:

Cryobiology: The Study of Life and Death at Low Temperatures (brief)

For more technical information on cryobiology, including vitrification, see:

Asymptote Cool Guide to Cryopreservation