At present, cryopreservation technology is only successful for cell lines and small tissues. More research is required before whole organs can successfully be cryopreserved while retaining their biological integrity. Given the importance of organ transplants and the growing field of tissue engineering, perfecting cryopreservation methods would have a profound impact on medicine.
There has been progress in cryopreservation and cryogenics. A team led by Hal Sternberg of Biotime claimed to bring back to life baboons that were previously cooled to one degree Celsius. They injected a substance called Hextend to replace the blood and protect the cells from deterioration. Incredibly, this may soon become routine for emergency care patients. Hasan Alam at Massachusetts General Hospital is working on a similar approach to drop the temperature of emergency patients and protect the bodies from damage while undergoing surgery. Replacing the blood of critical care patients with a saline solution and lowering their temperature is being tested in US hospitals. At a more basic science level, Gregory Fahy and colleagues at 21st Century Medicine vitrified (i.e., stored at < -130°C without ice formation, see about page for details) a rabbit kidney and then transplanted it into a live animal with the kidney maintaining some degree of function. The same team showed that rat and rabbit brain slices can be vitrified and rewarmed and still maintain neural responses. Interestingly, there are also species of insects that appear to survive complete freezing during winter. Likewise, some species of frogs can produce their own antifreeze during winter and be partly frozen.
By perfecting cryopreservation technologies, donor organs can be preserved earlier and with no further loss in viability. Eradicating wastage through poor storage would save many thousands of lives. As progress continues in tissue engineering, vitrification could hold the key not only to long-term organ banking, but in storage of personalised lab-grown tissue replacements. Low-cost, long-term organ banking through safe, super-low temperature vitrification of whole organs that could be rewarmed when needed for transplant would equate to countless thousands of lives saved each year and lay the foundations for personalised tissue engineering and regenerative medicine. Therefore, vitrification would have applications in many areas.
Potentially, vitrification may allow for human cryopreservation or suspended animation. While it remains in the realm of science fiction, reversible and safe human cryopreservation would be a revolutionary technology in the field of critical-care. Patients with terminal diseases, including children, could opt to be placed on cryostasis until a cure were discovered. In a sense, we would have an alternative to death (cryonics), which has profound philosophical, ethical and medical implications. Suspended animation from reversible cryopreservation may also be necessary for space exploration, as depicted in science fiction as various forms of cryosuspension or cryosleep.
In summary, advances in cryopreservation would be of immense importance for medicine to meet the demands of our ageing populations. It will be also critical for the development of emerging technologies, such as stem cell research and tissue engineering and potentially human cryonics.