A new method to avoid ice formation during cryo-preservation

The Liquidus tracking method can prevent the formation of ice crystals in organic material.

The main danger for animals exposed to cold weather is the risk associated with freezing and the formation of ice crystals within the body in general and intracellular in particular. Cold resistant animals use a variety of methods to combat ice formation, including increasing the salinity of the blood and thereby decrease the freezing point, using special chemicals to produce anti-freeze liquids. Researchers have long been interested in discovering ways in which organic materials can be frozen without causing damage to the tissue. The most famous application of this is the science fiction idea of letting astronauts hibernate during long space voyages. However, a more immediate application is the medical need for cryo-preserving organs and tissue that are later to be used in organ transplantations. Researchers from the United Kingdom have now come up with a new method of freezing articular cartilage.

Traditionally, it has been a problem to prevent ice formation in the living cartilage cells. The cryoprotectant dimethyl sulphoxide (Me₂SO) has been shown to prevent ice formation, but so far only at low temperatures, and not during the actual freezing process. However, the British researchers have developed a computer controlled method, the liquidus tracking method, where both temperature and Me₂SO are precisely controlled during continuous stirring of the sample. Trial experiments show that the freezing and defreezing process does not have any adverse effect on the most important biomechanical property (instantaneous compressive modulus) of cartilage.

Source: Wang, L.; Pegg, D. E.; Lorrison, L.; Vaughan, D. and Rooney, P. (2007). Further work on the cryopreservation of artiuclar cartilage with particular reference to the liquidus tracking (LT) method. Cryobiology 55:138-147.

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