A century ago, organ transplantation seemed such a miraculous operation that the prospects for its introduction into medicine were mainly discussed by science fiction writers. Today, over one hundred thousand transplant operations are performed in the world every year - from routine kidney transplants to unique heart transplants. But the real miracles seem to be yet to come.
THE MYSTERY OF PROFESSOR DOWELL
One of the most reprinted novels by the Soviet science fiction writer Alexander Belyaev is Professor Dowell's Head, but few people know that it was preceded by a story of the same name. When the story was first published in 1925, the writer provided it with a short introduction, in which he talked about his contemporary achievements in the field of transplantation: “Is it possible to revive and prolong the activity of a heart cut from a fresh corpse? Experiments on revitalizing the heart are already twenty years old and have led to favorable results. A number of scientists have worked to solve this problem: Gaskell and Eswald, Ashov and Tavara, in America - Kerel and others."
Of particular interest here is the last name - "Kerel". We are talking about the French surgeon Alexis Carrel, who was the prototype of Dowell and who in 1912 received the Nobel Prize for "work on vascular suture and transplantation of blood vessels and organs." The generally recognized success of Carrel's operations, about which the press wrote a lot, could serve as a guiding impetus for Belyaev's imagination, although in his introduction the writer was mistaken - Carrel worked for in America, and in France. Transplantation continued to be the focus of science fiction literary focus almost until the early 1930s. Here it is enough to recall the novel "Amphibian Man" (1928) about a young man with shark gills and the story "Go-to-go" (1930) about an elephant with a human brain. However, then the interest faded away, because, as it seemed to Belyaev, there were no new revolutionary breakthroughs. Fantastic was wrong.
ANATOMIC CHIMERS
The tasks that the transplant specialists set themselves were so ahead of their time that they did not correspond to existing technologies. Because of this, only in isolated cases did they manage to achieve success. Take the head transplant that Belyaev wrote about.
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The first experiment of this kind was conducted on May 21, 1908 by the American Charles Guthrie. He took two dogs and connected their circulatory systems so that the blood of the first dog would go through the head of the second; then he detached the second dog's head and sewed it to the base of the first dog's neck. The sewn-on head lived for only a few minutes, demonstrating the simplest reflexes, but most importantly, Guthrie proved the principle possibility of such an operation, which inspired his followers.
However, it took half a century to bring his work to an acceptable result. The Soviet biologist Vladimir Petrovich Demikhov, who also had a technical education, coped with the task. He began his scientific career very early: in 1937, as a third-year student, he designed an artificial heart and implanted it in an experimental dog. Nine years later, Demikhov managed to implant a second heart to another dog, changing the natural circulatory system, and soon he was able to completely transplant the cardiopulmonary complex, which became a real sensation in world surgery. Unfortunately, in the Soviet Union, Demikhov's unique operations were skeptical, and he was forced to change his place of work.
Vladimir Demikhov conducted his most famous experiment in a laboratory located in the basement of the Sklifosovsky Institute for Emergency Medicine: in 1955, for the first time in history, he successfully transplanted a puppy's head (with forelimbs, lungs and esophagus) onto the body of an adult dog. Subsequently, within ten years, Demikhov repeated this operation twenty times; one of his "anatomical chimeras" lived for a whole month, they even made a color documentary about her, which pretty much shocked the public.
Thanks to Demikhov's work, transplantation has made a big step forward. For example, the South African surgeon Christian Barnard, who performed the first successful human heart transplant in 1967, called Demikhov his teacher, and Professor Robert White, who in 1970 transplanted a monkey's head from one body to another, in his reports directly pointed to experiences of the Soviet predecessor.
EXPERIMENTAL CANAVER
Despite huge expectations, transplantation stumbled upon the problem of rejection of donor organs by the immune system of the recipient (that is, the patient to whom the organ is transplanted), and for a long time scientists could not determine what determines the rate of rejection. It turned out that compatibility is determined by genetic proximity, so the best donors are the closest relatives.
The immune system has been successfully suppressed with cyclosporine, a powerful drug discovered in 1972. But if we are talking about a head transplant, then it is necessary to solve another important problem - the reunification of the spinal cord, without which, instead of a new “chimerical” person, a “chimerical” paralytic will turn out.
Currently, the problem is being solved using fusogens - substances that promote the reunification of bonds between cells, such as, for example, polyethylene glycol and chitosan. In 2014, German researchers showed the effectiveness of polyethylene glycol (PEG): rats, paralyzed by surgical separation of the spinal cord, restored locomotor activity within a month.
The success of PEG prompted the Italian surgeon Sergio Canavero in 2015 to declare that the current level of medicine is sufficient to carry out a human head transplant. Although in the scientific world his statement was taken with skepticism, he is consistently moving towards his goal.
First of all, together with a group of South Korean scientists, he reproduced an experiment to restore the spinal cord in experimental mice using PEG. The next step was the use of the so-called "Texas" PEG solution, which was added electrically conductive graphene nanoribbons, which serve to support the growth of neurons in the right direction. Due to this, the process of spinal cord regeneration was noticeably accelerated: in experimental rats with a damaged spine, full recovery of all functions took two weeks, in an adult dog - three weeks.
In September 2016, Sergio Canavero announced that he had performed a successful head transplant on a monkey. In the experiment, he was assisted by Chinese scientists. Fusion of the spinal cord was not performed this time - the group practiced technical procedures for stitching the vessels. To prevent the death of brain cells, the head was cooled to 15 ° C. The "Anatomical Chimera", consisting of two monkeys, lived for twenty hours and was put to sleep.
The Italian scheduled the main human head transplant operation for December 2017. His patient will be a thirty-year-old Russian programmer Valery Spiridonov, who suffers from an incurable genetic disease - spinal muscular atrophy. The operation will probably take place in one of the leading Vietnamese clinics and will take, according to calculations, about thirty-six hours.
Many reputable scientists involved in transplantation or spinal cord rehabilitation have emphatically distanced themselves from Sergio Canavero and call him an "adventurer." They believe that the experiment with the transplant of Spiridonov's head onto a donor body will inevitably fail, which will negatively affect the reputation.
What if the Italian succeeds? Then his technology will attract huge investments, because it can be used to heal many people who are partially or completely paralyzed. True, the question of donor bodies will come up sharply, but that's another story.
Anton Pervushin