Is it better to thaw cells fast or slow and why is slow freeze and quick thaw principle used in cryopreservation?
An established view in cellular cryopreservation is that following freezing, cells must be warmed rapidly (≤5 minutes) in order to maintain high viability. It was demonstrated that small, slow increments in both the freezing and thawing processes prevented the rapid formation of ice crystals that increased membrane-bound solutes associated with early cell death. This is by far the safest method for thawing, especially when thawing whole food items. It also takes the longest amount of time. Depending on the type of food you are thawing, five pounds of food can take 24 hours to thaw.
funny comparison between food and cells. Need to read basics of cryopreservation,
It is better to thaw cells slowly. This is to ensure that the cells morphology, that is the cell nucleus, cytoplasm, and organelles are not destroyed by fast thawing; rather, there are preserved.
In the slow freezing method, ovarian tissue is slowly frozen to approximately −140 °C, followed by the storage of the tissue in liquid nitrogen at −196 °C. Cryopreservation processes can generally be grouped into the following types slow freezing vitrification, which involves the solidification of the aqueous milieu of the cell or tissue into a noncrystalline glassy phase subzro nonfreezing storage; and preservation in the dry state. During freezing, cells may undergo severe dehydration (solution injury) by slow cooling and IIF (ice injury) by fast cooling. The optimal cooling rate should be slow enough to avoid IIF and fast enough to avoid severe dehydration. Whereas in conventional slow freezing the concentration of the cryoprotectant is low and the cooling rate is very slow to avoid ice crystallization, vitrification is an ultrarapid cooling technique that requires a high concentration of cryoprotectant. For the greatest cell viability, it is important to freeze the cells slowly. The opposite is true for thawing—thaw quickly! Remove cryovials from the liquid N2 tank and immediately place them in a 37°C water bath