Today we know him for being one of the fathers of environmentalism and founder of the Gaia hypothesis , according to which the Earth is an organism that regulates itself to stay alive. But back in the 1950s, James Lovelock was a young scientist at the National Institute for Medical Research in London with a strange job: reanimating frozen hamsters. The experiment consisted of reducing the body temperature of the rodents until their heart stopped beating. Later, he revived them by applying a metal spoon heated in the flame of a lighter to his chest. This procedure loosen the heart muscle, which after four or five minutes began to throb again while the rest of the animal remained cold. Soon after, spontaneous respiration returned and, after a hot water bath and several days in the incubator, the hamsters were fully recovered. Furthermore, many were subjected to the same trance several times.
To minimize the risk of burns to the thorax, the British biochemist – creator of a good handful of scientific instruments – got hold of an airplane transmitter, disassembled it and with its components built a simple diathermy device – heat production in tissues – by microwave. Research on the effects of freezing in animals led Lovelock to rethink the concept of life: is a hamster with all its organs pierced by ice crystals, including the brain, alive or dead? His works, including the question mark, put a breakthrough in the field of cryobiology , the branch of biology that studies the effects of low temperatures.
In nature we find organisms, from bacteria to higher animals, that tolerate freezing for long periods of time. Humans, at the moment, we have not reached this capacity naturally, but it is possible to keep cells and tissues for years in a refrigerator, as is done with plasma, semen, ovules, corneas or cord stem cells umbilical. Perhaps, in the not too distant future, doctors will have frozen organ banks for transplants . Or they can even resurrect those people who decided to be frozen after their death and whose bodies are preserved in tanks of liquid nitrogen.
Normally, the temperature of the human body oscillates between 36 ° C and 37 ° C; if it falls below 35 ° C, you go into hypothermia. Then, the muscles become numb, tremors occur, the skin turns blue-gray, and we slowly lose the ability to think and move. When the heart stops beating, the blood no longer carries oxygen to the cells. However, at lower temperatures, the body slows down, on the order of 5% -7% for each degree decreased. By working more slowly, cells need less oxygen. That’s what explains why some people who fall into a frozen lake or are trapped by an avalanche of snow can be revived even if they have stopped breathing for a few minutes.
Live after eighty minutes under the ice
The lowest body temperature that a human being has survived is 13.7 ° C. In 1999, a Swedish radiologist, Anna Bågenholm, fell headfirst into a frozen river while skiing in the mountains of Norway. She was conscious for forty minutes – she was lucky enough to be trapped in an air pocket – before she suffered a cardiorespiratory arrest. By the time they were able to rescue her, she had already been under the ice for eighty minutes. After ten days in intensive care, Bågenholm woke up paralyzed from the neck down. Over time, he managed to recover almost completely from the accident, although with hand and foot injuries.
In recent years, therapeutic or induced hypothermia is being used with increasing frequency to prevent or mitigate neurological injuries . In some neonatal units, for example, they use this technique with children who have suffered a lack of oxygen and blood flow to the brain during delivery. Studies show that keeping the body temperature at 33.5 ° C for 72 hours reduces the risk of both death and disability in the future by giving doctors time to treat the baby.
The most ambitious project in this field is being carried out by a group of American scientists led by Peter Rhee and Samuel Tisherman, from the universities of Arizona and Maryland, respectively. The researchers affirm that it is possible to keep whole bodies in a state of suspended animation , that is, between life and death, for a few hours. They have already demonstrated this in trials with pigs, which caused massive hemorrhage by mimicking the effect of multiple gunshot wounds. The technique consists of draining all the blood from your body and replacing it with an ice-cold saline solution, which cools the body to 10ºC and stops almost all cellular activity. After the injury is treated, the blood is pumped again and the individual slowly warms up.
Rhee and Tisherman are already prepared to carry out clinical trials with gunshot or stab wounded at the Pittsburgh Presbyterian Hospital in Pennsylvania. And, over time, they want to include victims of road accidents or falls with serious injuries as well. The goal, according to these experts, “is for the cold to reduce the risk of organ damage due to cardiac arrest .”
The blood is exchanged for antifreeze
Unlike suspended animation, Cryonics keeps patients after officially certifying their demise, in the hope that future technology will bring them back to life. On this occasion, the blood is replaced by an antifreeze –similar to the one we put in the car’s radiator– and the body is kept in liquid nitrogen, at -196 ° C. The cryopreservative substance prevents the formation of ice microcrystals that break down cell structures. It is the so-called vitrification, also used with embryos, which are preserved for years to be implanted in the mothers’ wombs when required.
“The problem, in the case of adult humans, is that we do not know how to reverse the process,” says Lluís Estrada, former head of Clinical Neurophysiology at the Tarragona University Hospital. Yet. Because reversible cryopreservation is an area of scientific research that is showing promising results.
As early as 2005, an Israeli team successfully reimplanted the right ovary of eight sheep after two weeks. Blood flow instantly resumed, and soon the animals were producing eggs normally. The ultimate goal of this particular type of experiment is to safeguard the fertility of women who, for example, receive chemotherapy.
Cryopreservation of ovarian tissue is one of CryoBioTech’s lines of research. For Ramón Risco, director of this group of scientists at the Higher School of Engineers of the University of Seville, expanding it to larger organs, such as the heart and kidneys, would allow doctors to have banks of spare parts ready for transplantation.
But before they got to that point, they would have to clear a major hurdle: antifreeze toxicity. “Most of them are alcohols, and therefore harmful in the concentrations necessary to vitrify,” says Risco. And he continues: ” If we replace a high percentage of the organ with these substances, we can become intoxicated” . The strategy that they follow in CryoBioTech is “to visualize, by means of tomography images, how the organ is being loaded with antifreeze”. This way they control the exact ratio before it spoils.
Frozen brains recovered
Should the technique advance so far that a cryopreserved person could be resurrected in the future, the toxicity could have serious consequences for their body, especially their brain. How to preserve neurons after a thaw? Would the synapses – or connections – be maintained between them? Of the 250 to 300 people who, according to Estrada’s calculations, are floating in tanks of liquid nitrogen at companies like Alcor and the Cryonics Institute, some of them have preserved only their heads, known as neurosuspension. The defenders of this practice consider that identity is contained in the brain, and that it will be enough to provide a new body to the thinking organ.
The idea is not so far-fetched if we take into account that, in early 2016, scientists from the Californian company 21st Century Medicine (21CM) recovered, for the first time, the brain of a mammal. The experts applied to a rabbit a technique called aldehyde-stabilized cryopreservation, which consists of filling the cerebral vascular system with chemicals that cool it down to -135 ºC. During this process, the synapses remained intact, demonstrating that neural areas related to memory and learning can be preserved .
A year earlier, a team of Alcor scientists, in collaboration with CryoBioTech, found evidence that memories can survive freezing in simple organisms such as the nematode worms Caenorhabditis elegans . “If we can apply this technique to the kidneys and livers, why wouldn’t we be able to do it with the brain, which is also an organ?” Asks Risco.
Cryonics as an alternative to biological death raises many doubts within and outside the scientific community . First, because it has not yet been proven to work: some think that the sole purpose of companies is to profit. Although, in reality, the cost of a cryogenization is not excessively high either. It can range, according to Estrada, between 40,000 and 250,000 euros. The variation is explained because “in institutions like Alcor they consider that a monetary reserve should be made so that the maintenance of the body can be covered with the interest generated. If that person were to revive in the future, they would have a capital with which to cope with life ”, explains the neurophysiologist.
Cryogenized just in case
But what would that person paint in a world that does not belong to him? It is another of the criticisms made by the detractors of human cryopreservation. The possibility that there would be overpopulation in the future would not be a problem either, because the practice is not so widespread either. Estrada assures that he does not see any ethical dilemma, since stopping biological time in the hope that finding a cure is, after all, a personal decision, not even at odds with religious beliefs. Risco is of the same opinion: “There are people who want to be frozen in case they could recover something of what they were. I see it as an experiment, where there is always an experimental group and a control group. We already have the second: all the people who die. There are those who think that we are going to be able to recover those bodies. Who knows? I don’t dare to decide. “
Images: CC0, USDA Gene Bank, Alcor Life Extension Foundation
