Cryoprotectant

A substance that reduces biological damage during freezing or severe cold. Cryoprotectants work by limiting ice formation, stabilizing cellular structures, or both.

Vitrification: The formation of a solid amorphous state without crystallization, often achieved by rapid cooling or concentrated solutes. Some cryoprotectants suppress ice crystals by helping water vitrify during cooling.
Glycerol: A small, water-soluble alcohol used as a cryoprotectant for cells, sperm, and other biological materials. Its membrane permeability makes it a standard intracellular protectant in freezing protocols.
Cryopreservation: The preservation of cells, tissues, or other biological material at low temperatures, often below −130 °C. Cryoprotectants are central to limiting injury during freezing and long-term storage.
Cryoprotectant toxicity: Cellular damage caused by exposure to cryoprotectant chemicals, especially at high concentrations or temperatures. The compounds that prevent freezing injury can themselves harm cells.
Colligative properties: Properties of solutions that depend on the number of dissolved particles rather than their chemical identity. Dissolved cryoprotectants lower water’s freezing point and change ice formation.
Dimethyl sulfoxide: An organosulfur compound that dissolves in water and penetrates biological membranes. DMSO is a widely used permeating cryoprotectant for cells and tissues.
Stem-cell banking: The collection and long-term storage of stem cells for research or clinical use. Banked cells are commonly frozen with cryoprotectant solutions to preserve viability.
Slow freezing: A controlled cooling method that allows water to leave cells as extracellular ice forms. It can reduce the need for extreme cryoprotectant concentrations used in vitrification.
Osmosis: The movement of water across a selectively permeable membrane in response to differences in solute concentration. Cryoprotectant-driven water shifts can shrink cells before freezing and cause injury if excessive.
Ethylene glycol: A small diol used as a solvent and as a permeating cryoprotectant in biological preservation. Its rapid cell entry makes it useful in vitrification mixtures, especially for embryos.

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