Head transplant

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A head transplant is the transplantation of a head onto another body. Since the donor and recipient should be of the same type for medical feasibility of such an operation, the head transplant is counted as an allogeneic transplant . The first tests on dogs were made in the 1950s. The Italian surgeon Sergio Canavero has announced the world's first human head transplant for spring 2018. In November 2017, it became known that Canavero 's planned transplant in China would be banned by the local health authorities.

First experiments on animals

The last head transplant shown by Wladimir Demichow on January 13, 1959 in the GDR

Russian surgeon Vladimir Petrovich Demichov garnered international attention in the 1950s when he created a two-headed dog. The Time magazine reported in 1955 about it. In his experiment, Demichow transplanted the front part of a puppy including its head onto the adult German shepherd Rylschi. For a short time the operation seemed successful, both heads moved, barked and ate. But after a few days the dog died.

In 1970, the US surgeon Robert J. White managed to transplant a monkey's head onto another body. However, the spinal cord could not be connected, so that the animal was paralyzed. In addition, the monkey had to be artificially ventilated. Despite these efforts, the animal died after nine days as a result of an immune reaction that resulted in the body rejecting the head.

More recent experiments were carried out on mice and monkeys by the Chinese doctor Ren Xiaoping . He experimented on more than 1000 mice, the maximum survival time of an operated test animal being one day. The surgeon was also able to transplant a monkey's head. In doing so, he succeeded in establishing blood circulation without the primate suffering any neuronal damage. However, Xiaoping was unable to connect the spinal cord either, so the monkey was paralyzed and, for ethical reasons, was euthanized after 20 hours.

The first human head transplant

For December 2017, Sergio Canavero had planned to transplant the head of the Russian Valeri Spiridonov onto a donor body. Canavero presented how the procedure should take place in September 2014 at the conference of the American Academy of Neurological and Orthopedic Surgeons in Annapolis . Spiridonov found out about the Canaveros vision in June 2013 and volunteered for the procedure. However, he stated that he would only agree to this after a successful animal experiment.

Reason for the transplant

Valeri Spiridonow suffers from Werdnig-Hoffmann Disorder , a rare form of muscle atrophy also known as spinal muscular atrophy . It leads to the death of nerve cells in the spinal cord and thus to paralysis of the muscles. Due to the resulting lack of exercise, the muscles that are still functional also recede. In addition, the lack of movement leads to deformation of the skeleton.

Procedure and difficulties

Repulsion of the head

As with any organ transplant, there is a risk that the transplanted tissue will be rejected by the immune system . On the other hand, drugs that have already been successfully used in other transplants can help.

Blood supply

The blood supply to the brain is a bigger problem. In order to gain time to connect the head to the blood circulation of the donor body, the patient's body should be cooled to 12 to 15 ° C. As a result of the reduction in body temperature, the cells require less energy and therefore less oxygen. Veit Braun , secretary of the German Society for Neurosurgery , assumes that the patient will suffer a stroke as a result.

Connection of head and body

After the patient has been brought to the target temperature, the neck tissue should be removed. The next step is to connect the main vessels of the head and body to restore blood circulation. The spinal cord is then severed with a straight, sharp incision to minimize injuries to the nerves. However, nerve fibers do not grow back together on their own. To counter this problem, the chemical polyethylene glycol (PEG) is to be used so that new nerve fibers can grow out of the brain and the gap in the spinal cord can be closed. However, this procedure could only be successfully applied to a single person. The originator of this method, the German neurobiologist Hans Werner Müller from the Molecular Neurobiology Laboratory at the University of Düsseldorf , does not, however, believe that the project will be successful. Should the PEG method fail, Canavero believes that the ability to move could also be generated by artificial current impulses, since the spinal cord is only able to control complex movements to a limited extent.

Recovery period

In order to make the healing process as smooth as possible after the operation, the patient is placed in an artificial coma for about four weeks. This prevents unwanted movements and increases the chances of recovery. Following this, the patient should be able to move his head and speak again. It will probably be a year before the patient can walk again.

Ethical aspects

In addition to the medical hurdles, there are also ethical concerns about head transplantation . The question of the definition of life can be decisive for the justifiability of the intervention . Under the assumption that a person's personality is anchored exclusively in the brain, Canavero's project can be ethically justified, according to neurologist and bioethicist Patricia Scropko of the Salinas Valley Memorial Healthcare System in California. The WHO said it was unlikely that an ethics committee would speak out in favor of the operation. According to the President of the American Association of Neurosurgeons , Hunt Batjer , the operation could even trigger an unexpected form of madness in the patient .

Web links

Individual evidence

  1. ↑ a b History of Medicine: Doctors Without Borders. In: SPIEGEL ONLINE. July 29, 2009, accessed March 10, 2016 .
  2. ↑ a b c d Jan Vollmer: He is ready for the first head transplant of mankind. In: Welt Online. January 18, 2016, accessed March 10, 2016 .
  3. ↑ Markus Keßler: Head transplantation should make people immortal futurezone.at, July 5, 2016
  4. ↑ orf.at: China wants to ban planned head transplants . Article dated November 25, 2017, accessed November 25, 2017.
  5. ↑ a b c Florian Rötzer: Italian doctor announces head transplant. In: Telepolis. February 28, 2015, accessed March 10, 2016 .
  6. ↑ Isabell Beer: Valeri Spiridonow: He will have his head transplanted next year! In: Berliner-Kurier.de. January 22, 2016, accessed March 11, 2016 .
  7. ↑ a b c d Irene Berres, Julia Merlot: Announced head transplant: "That goes wrong". In: SPIEGEL ONLINE. June 13, 2015, accessed March 11, 2016 .
  8. ↑ a b The world's first head transplant. In: bluemind.tv. April 27, 2015, accessed March 11, 2016 .
  9. ↑ Heike Le Ker: Electro-stimulation: paraplegics can move their legs again. In: SPIEGEL ONLINE. April 8, 2014, accessed March 11, 2016 .