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The miracle of biological cryogenics: Why can some organisms survive at -196°C?
In the scientific community, freezing technology has always been an important direction in exploring the continuation of life. Biofreezing, or cryopreservation, aims to freeze cells, tissues or organs to extend their shelf life. This technology allows any cellular metabolism that could damage biological materials to be effectively halted at low temperatures (typically -80°C or -196°C using liquid nitrogen).
This technology not only plays an important role in preserving biological samples, but also plays a huge role in transporting biological samples over long distances. For the osmotic shock and physical stress that cells undergo during freezing, researchers often add some special molecules called cryoprotectants (CPA) to reduce these risks. These cryoprotectants are primarily inspired by nature's cold-resistant creatures, such as trees, wood frogs and tardigrades.
"Microbial organisms such as tardigrades resist freezing by replacing most of their internal water with sugar, which prevents crystallization from occurring, which can cause damage to cell membranes."
Examples of natural cryopreservation
In nature, many organisms have amazing frost resistance. Wood frogs, for example, are able to accumulate urea in their blood and other tissues in preparation for winter. Glycogen in the liver is also massively converted into glucose when faced with the formation of internal ice crystals. These substances all act as cryoprotectants, limiting ice formation and reducing osmotic shrinkage of cells. Research shows that frogs can experience multiple freezing and thawing events in winter, provided that 65% of their body water does not freeze.
History of Cryopreservation
As for the early theory of cryopreservation, James Lovelock proposed in 1953 that the damage to red blood cells during freezing was mainly due to osmotic pressure. He conducted a series of experiments and confirmed that certain animals (such as hamsters) can withstand 60% of the water freezing under slow cooling.
With the advancement of freezing technology, cryopreservation of human body materials began to enter the application stage in 1954. Subsequently, in 1966, the first human remains were cryopreserved. In 1967, James Bedford's body became the first body in history to be cryopreserved with the hope of future resurrection.
Risks during cryopreservation
During cryopreservation, cells may encounter several risks of damage, including solution effects, extracellular ice crystal formation, dehydration, and intracellular ice crystal formation. Although these effects can be reduced by cryoprotectants, upon freezing, the protective effect of the preserved material against further damage is enhanced.
"When cells are frozen, if the cooling rate is slow enough, water can leave the cell enough to avoid the formation of deadly internal ice crystals."
Main prevention methods of cryopreservation risks
Main techniques to prevent freezing damage include controlled cooling rates and slow freezing, as well as a newer technique called vitrification. Slowly programmable freezing technology has been widely used in fields including humans, animals, and cell biology.
The vitrification process quickly cools the sample and prevents ice crystals from forming, thereby reducing possible damage during the freezing process. This technology has been introduced for reproductive cryopreservation since the mid-1980s and has been successfully used in various clinical practices to date.
The significance of cryopreservation for biotechnology
With the development of science and technology, the application of cryopreservation is not limited to the preservation of biological samples, but will also extend to fields such as gene therapy and stem cell research. Cryopreservation technology opens broad prospects for future biological research and clinical applications.
For many people or creatures facing existential threats, the advancement of this technology means that new life possibilities can be found in the future. Isn't this worth pondering?
