Kriopreservointia

Kriopreservointi (cryopreservation) is a collection of techniques used to preserve biological material by cooling it to cryogenic temperatures, typically around -196 °C in liquid nitrogen. At these temperatures, metabolic processes virtually stop, allowing long-term storage with minimal degradation.

Common methods include slow freezing, which gradually lowers temperature with controlled-rate equipment to minimize ice crystal formation, and vitrification, which uses high concentrations of cryoprotectants and rapid cooling to avoid ice crystals entirely. Cryoprotectants, such as dimethyl sulfoxide or glycerol, protect cells during cooling but can be toxic at higher concentrations.

Biological materials preserved include reproductive cells (sperm, oocytes, embryos), stem cells, blood products, tissues, and even whole organs for research and potential transplantation. In agriculture and wildlife, kriopreservointi is used for semen banks, seed banks, and preserving genetic material from endangered species. In medicine, it enables fertility preservation for cancer patients, storage of donated gametes, and long-term biobanking of samples for research.

Storage facilities rely on cryogenic vessels and dewars with liquid nitrogen to maintain stable temperatures. Long-term viability depends on proper handling, rapid retrieval processes, and monitoring to prevent contamination, temperature fluctuations, or nitrogen loss.

History notes: the field developed in the mid-20th century with early successes in mammalian sperm and later embryos. Today kriopreservointi is central to reproductive technology, biobanking, and conservation, though it presents challenges such as cryoprotectant toxicity, equipment costs, and ethical considerations around donor consent and material ownership.