A cryoprotectant is a substance used to protect biological tissue from freezing damage (i.e. that due to ice formation).
For years, glycerol has been used in cryobiology as a cryoprotectant for blood cells and bull sperm, allowing storage in liquid nitrogen at temperatures around −196 °C.
A successful discovery may eventually make possible the bulk cryogenic storage (or "banking") of transplantable human and xenobiotic organs.
In this way, the cryoprotectant prevents actual freezing, and the solution maintains some flexibility in a glassy phase.
Thus, as the cryoprotectant replaces the water molecules, the biological material retains its native physiological structure and function, although they are no longer immersed in an aqueous environment.
[2] A mixture of formamide with DMSO (dimethyl sulfoxide), propylene glycol, and a colloid was for many years the most effective of all artificially created cryoprotectants.
Vitrification has important applications in preserving embryos, biological tissues and organs for transplant.
Glycerol and DMSO have been used for decades by cryobiologists to reduce ice formation in sperm,[3] oocytes,[4] and embryos that are cold-preserved in liquid nitrogen.