Cryonics: is there life after freezing?
Journalistic ethics requires that articles on controversial topics always have more than one point of view. Cryonics is one of the most controversial areas of practical activity, in which many flatly refuse to recognize science. Therefore, in order to fulfill our professional duty, we will start with the skeptical part.
The possibility of reviving a frozen person with the help of future technologies cannot be 100% guaranteed. No self-respecting cryofirm will subscribe to a promise to revive the patient after a certain number of years. Both research in the field of cryonics and the business of preserving the bodies of cryopatients are based on the belief that the most promising technologies of today will receive worthy development. We are talking about growing organs and creating their artificial counterparts, about nanotechnology in medicine, about modeling consciousness. This position gives ample room for skepticism, so finding criticisms of cryonics will not be the slightest difficulty.
However, not all skeptics know how difficult it is to preserve the body without damaging it, and what advanced technologies are behind this process. These methods are associated with the quite tangible achievements of today, such as storing sperm with the possibility of fertilization 20 years after preservation or freezing of human embryos ranging in size from several tens to several hundred cells with the subsequent return to life.
These successes alone make us take the prospects of cryobiology seriously. Danila Medvedev, chairman of the board of directors of KrioRus, told us about them.
Process, not result
In order to think about a temporary suspension and subsequent restoration of life, a deep understanding of death is necessary. Understanding that dying is not a one-time event, but a time-consuming process consisting of several stages, has enabled many patients to return to life after clinical death as a result of resuscitation procedures.
Actually clinical death is characterized by cardiac arrest, cessation of breathing, the disappearance of external signs of life. In the absence of blood circulation, oxygen ceases to flow to the cells of tissues and organs. Unfortunately, the cells of the central nervous system, in particular the cerebral cortex and subcortical structures, are most sensitive to anoxia (lack of oxygen).
When diagnosing clinical death, doctors usually have only a few minutes left to carry out resuscitation measures. However, in some cases, the duration of clinical death may increase to several tens of minutes. One of such cases is hypothermia, a decrease in body temperature (usually up to 20–25 ° С), which slows down biological processes. Hypothermia is used in surgery for some operations requiring cardiac arrest.
When the bioelectric activity of the brain ceases, brain death is detected. Resuscitation measures cease, and the person is recognized dead, including from a legal point of view. What happens in the cells of organs, tissues and the brain at this moment?
Different tissues exhibit varying degrees of resistance to anoxia. The heart can stretch up to two hours after biological death, the kidneys and liver - up to four hours, the muscles and skin - up to six, and the bones - up to several days. The brain has the least margin of safety, but its cells do not die at the same time, all at once.
A cell is a biological mechanism that constantly consumes energy produced by oxidative processes. With the cessation of energy intake, the cell ceases to recover and respond to external stimuli. The permeability of the plasma membrane is gradually disturbed, the ion concentration changes, organelles swell and rupture of their membranes.
It turns out that for some time after biological death, many brain cells remain alive, and some die, but retain most of their structural elements. In fact, all cryonics is based on the assumption that the most careful preservation of the physical structure of the brain will allow the patient to be transferred to the future.
It is logical to assume that a person’s personality is determined by his memories - more precisely, by the contents of long-term memory. It is known that the processes of thinking and remembering are determined by the connections between individual neurons, sometimes far removed from each other. In 2009, the US National Institute of Health launched the Human Connect project (similar to the genome), aimed at mapping neuronal connections.
Basic memory theories in one way or another imply that the formation of these connections depends on changes in the physical structures of the brain. The synaptic theory suggests that when memorized, the conductivity of the synapse (the contact between two neurons) changes. This is due to the activation of additional protein receptors, a change in the chemical characteristics of the synaptic membrane and even an increase in the diameter of the synapse. Biochemical theories state that proteins, peptides, DNA or RNA can be carriers of long-term memory.
Cryonists do not promise to keep the brain in its original form, without the slightest damage. But medical practice suggests that traumatic brain damage does not always lead to memory loss. In addition, there is hope that in the future, nanomedicine will allow the restoration of slightly damaged cells, bringing them back to life.
Among scientists who experiment with freezing organisms to prolong life, there are many famous names: what are only Anthony van Levenguk and Robert Boyle. However, until the first half of the last century, these attempts were unsuccessful. Unfortunately, cold destroys cells.
The main danger arises at the time of extracellular water freezing, which leads to dehydration of cells. With the formation of ice, the amount of free water decreases, so the concentration of substances dissolved in this water increases. An osmotic pressure is formed, which removes water from the cells through the membrane, ultimately leading to a disruption in the structure of proteins.
The formation of intracellular ice is also possible. In the water contained inside the cell, salts are dissolved that prevent the complete conversion of water into ice up to temperatures close to -40 ° C. Due to this protective property, the cytoplasm remains liquid even in severe frosts. However, when approaching a critical temperature, water still crystallizes, destroying the cell.
At the beginning of the 20th century, the Swede Lindfors and the Russian botanist Maximov conducted successful experiments on freezing fragments of living tissues using glycerol. Cryoprotectants have been discovered - substances that prevent the formation of ice and protect the cell from destruction during cooling. Penetrating cryoprotectants that can pass through the cell membrane include glycerin, dimethyl sulfoxide, ethylene glycol and a number of other substances. Modern compounds include additional components that allow them to penetrate the blood-brain barrier separating the circulatory and central nervous systems and preventing the passage of toxins from the blood into the brain.
Cryoprotectants replace intracellular water, and also bind the remaining water, preventing the formation of crystallization centers. At temperatures below -130 ° C, vitrification or glass formation occurs: the solution goes into an amorphous state. In this “glass” the spatial structures of protein macromolecules freeze, which is important for preserving memory.
A matter of technology
When ascertaining biological death, it is important to cool the cryopatient to a state of deep hypothermia as soon as possible (several degrees above zero) in order to slow down biochemical processes, including cell necrosis. At the same time, they start perfusion - saturation of cells with a cryoprotectant solution through the circulatory system.
The solution in several stages, with a gradual increase in concentration, is pumped through the carotid artery, replacing the blood. Experts monitor the pressure of the solution: exceeding the permissible level will lead to damage to the vessels, and a sharp jump in pressure will indicate a blood clot that can be eliminated. Filling the vasculature, the solution exits through the jugular vein. The concentration of the solution at the outlet indicates the degree of completion of the process: if it is the same as at the entrance, then saturation has already occurred.
Perfusion of the head takes about two hours, saturation of the body can take from four to six hours. “Most patients now understand that the most promising technology is neuroprotection, that is, preservation of the head only, ” says convinced transhumanist Danila Medvedev. - On the one hand, this procedure is much faster and therefore gives more chances to preserve the structure of the brain, memory, personality. On the other hand, the current level of technology development allows us to judge that the medicine of the future will allow creating a new body for the patient, instead of restoring the old and the sick. ”
Upon completion of perfusion, the cryopatient is transported to the storage in a container with dry ice and immersed in liquid nitrogen for long-term storage at a temperature of -196 ° C. Today it is the most reliable way of conservation, which does not require constant attention and the availability of electricity.
The dews of the cryo-depository “Krio-Rus” are two-layer composite tanks. The space between the outer and inner walls of the dewar (20-30 cm) is filled with perlite (volcanic rock), air is pumped out of it. The vacuum between the walls is maintained by a pump, which is turned on approximately every two weeks. About once a month, liquid nitrogen is added to the dewar (about a centimeter in level). In the future, it is planned to create a closed system, including a machine for liquefying evaporating nitrogen and an independent solar-powered power plant. “There are reasons why it is better to store patients at a temperature of -130, rather than -196 ° С. We are already developing an apparatus for storage in a gas environment (like in a refrigerator) with a computer control system and a dosed liquid nitrogen supply, ”Danila Medvedev shares his plans.
Quantity in quality
Today in the world there are three cryofirm with their own repositories: two in the USA and one in Russia. The number of cryopatients is approaching the mark of 300 people, of which 41 are preserved in our country.
If the chances of “resurrection” are recognized as non-zero, then their increase directly depends on the spread of the idea of cryonics, its integration into the scientific process, cultural context, and legal norms. For example, the introduction of cryonization into clinical practice will allow the patient to be immersed in hypothermia and begin perfusion immediately after the onset of biological death, which will significantly increase the chances of maintaining the structure of the brain. The development of the legislative framework, in particular the introduction of responsibility for disruption of the cryodepository, will help patients live to see the long-awaited breakthrough in medicine. Finally, elementary education will help to avoid situations where relatives impede the will of people who want to be cryoned.
At present, Krio-Rus is supporting the construction of a cryodepository in Switzerland, as well as participating in the development of a giant storage facility in China with the direct assistance of the state. Together with the unquenchable interest in related scientific and practical fields, such as transplantology, embryology, resuscitation and nanotechnology, this inspires hope that the first cryopatients, if they do not gain eternal life, will at least serve science.The article “The Only Chance of Immortality” was published in the journal Popular Mechanics (No. 3, March 2015).