Cryobiology

Cryobiology is the branch of biology that studies the effects of low temperatures on living systems and the development of methods to preserve biological material by cooling. It covers cellular, tissue, organ, and whole-organism responses to freezing and storage, focusing on processes such as ice formation, vitrification, osmotic stress, and the effects of cryoprotectants on viability and function.

Historically, cryobiology emerged in the mid-20th century with advances in cryogenic storage and the successful freezing and thawing of sperm and embryos. The introduction of liquid nitrogen storage and the development of vitrification techniques in the late 20th century enabled higher survival rates for many cell types and improved long-term preservation.

Key techniques include controlled-rate cryopreservation, rapid cooling with vitrification to avoid ice crystals, and dehydration methods in some contexts. Cryoprotectants such as glycerol, dimethyl sulfoxide (DMSO), and ethylene glycol reduce ice formation but can be toxic; careful loading, cooling, and warming protocols are required to minimize osmotic and chemical stress.

Applications span medicine, research, and biodiversity. Reproductive medicine preserves sperm, oocytes, and embryos; stem cell banks and tissue repositories rely on cryopreservation; organ preservation remains a major challenge. In agriculture and conservation, seed banks and biobanks store genetic material from crops and wildlife.

Challenges include intracellular ice formation, recrystallization during warming, and cryoprotectant toxicity. Other issues are equipment costs, standardization of protocols, and ethical or regulatory considerations. Ongoing research explores nanowarming, better cryoprotectants, and improved methods for organ and whole-body cryopreservation.