cryopreserved

Cryopreserved refers to the state of biological material that has been preserved by cooling to cryogenic temperatures, typically using liquid nitrogen at around -196°C, to halt metabolic processes and enzymatic activity. The goal is long-term storage while maintaining structural integrity and viability upon thawing.

The main methods are slow-freezing and vitrification. Slow-freezing gradually lowers the temperature with controlled rates and often uses lower concentrations of cryoprotectants to reduce ice formation. Vitrification uses rapid cooling with higher concentrations of cryoprotectants to prevent ice crystal formation by turning the solution into a glass-like state. Cryoprotectants such as DMSO, glycerol, ethylene glycol, and sugars help mitigate ice damage but can be cytotoxic, requiring careful optimization and gradual addition and removal during freezing and thawing.

Common applications include reproductive medicine (sperm, oocytes, and embryos), banking of umbilical cord blood stem cells, preservation of somatic and induced pluripotent stem cells, and long-term storage of biological samples for research and biobanking. In agriculture, cryopreservation is used for seeds and germplasm. In conservation biology, it supports preservation of genetic material from endangered species.

Viability after thaw varies by material and protocol; some tissues and organs are difficult to preserve and require specialized methods. Risks include ice crystal damage, osmotic stress, cryoprotectant toxicity, and contamination. Storage requires reliable freezers or liquid nitrogen systems, regular monitoring, and proper documentation and ethical/regulatory compliance for consent and ownership.