Cryovitrification

Cryovitrification is a preservation technique that prevents the formation of ice crystals in biological tissues or cell suspensions by replacing water with a mixture of cryoprotective agents at high concentration and cooling rapidly to very low temperatures. The process vitrifies the cellular contents into a glass‑like solid without the nucleation and growth phase that normally occurs during conventional freezing. Because ice crystals can rupture membranes and denature proteins, vitrification can greatly improve the post‑thaw viability of cells, embryos, organs, and biomaterials.

The chemistry of cryovitrification relies on cryoprotectants such as dimethyl sulfoxide, glycerol, ethylene glycol, or propanediol, which lower the freezing point, increase the viscosity, and interact with water molecules to inhibit crystallization. A typical protocol adds cryoprotectants to a cell or tissue sample, equilibrates to allow penetration, and then transfers the specimen into a cryovial or cryogenic chamber. The sample is cooled to temperatures below −120 °C through either rapid plunging into liquid nitrogen or through controlled ramping with a temperature‑controlled device. Some protocols incorporate high‑pressure application to further suppress ice nucleation.

Cryovitrification is employed in human reproductive medicine, where embryos and oocytes can be stored for extended periods without loss of developmental potential. It is also used in the preservation of stem cells, stem‑cell‑derived organoids, rare animal species, and small tissue samples for transplantation. In organ transplantation research, vitrified hearts, kidneys, or livers are being tested for extended “on‑demand” preservation, potentially reducing ischemic injury during transport. Additionally, cryovitrification has applications in tissue engineering, where scaffold materials impregnated with cells are vitrified for later implantation.

Overcoming challenges such as cytotoxicity of cryoprotectants and the need for rapid cooling remains a focus of ongoing research. The field continues to develop new formulations and cooling strategies that balance protective efficacy with viability, aiming to standardize vitrification protocols for clinical and research medicine.