Head transplant

A head transplant is a medical procedure in which the head of one living organism is surgically attached to the body of another. Scientists have been attempting to perform a viable head transplant on animals for more than a century, with little success. The transplantation process is incredibly difficult, prompting many medical experts to doubt it can be achieved even with modern surgical methods. Furthermore, the procedure carries with it a number of ethical and moral dilemmas that would make any attempt even more controversial. Despite the considerable obstacles involved, a successful head transplant would have the potential to revolutionize medicine. Patients who were paralyzed or had any number of terminal or degenerative illnesses could conceivably have their head grafted onto a healthy “donor” body. By 2024, no successful human head transplant had been attempted; however, a controversial Italian surgeon claimed to have developed the capability to perform such an operation.

Background

Surgeons as far back as the seventeenth century successfully attached pieces of bone from one living being to another as a way to heal damaged bone in the recipient. In the early nineteenth century, skin grafts were performed by taking skin from one part of a person’s body and transplanting it to another. By late century, doctors had found a way to transplant skin from one person to another. In 1906, an Austrian doctor performed the first cornea transplant, allowing a man blinded in an accident to regain his sight.

In the 1930s, doctors attempted to transplant a kidney from one human to another, but the recipient died. In 1954, doctors in Boston, Massachusetts, became the first to successfully perform such an operation when they transplanted a kidney from one twin to his brother. During the 1960s, the first lung, liver, and pancreas transplants were performed. South African surgeon Christiaan Barnard transplanted the first human heart in 1967. By the twenty-first century, doctors had successfully transplanted legs, arms, and faces from one human to another.

In many of the early transplant attempts, the transplants failed because the recipient’s body rejected the new organ. The body’s immune system interpreted the new organ as a foreign invader and launched an attack to destroy it. Using tissue from a close relative or a biologically compatible match lessens the likelihood the body will reject the transplanted organ. Doctors can also use drugs to suppress the immune system to keep the body from attacking the new tissue.

Overview

One of the main obstacles of head transplantation is maintaining blood flow to the brain during the procedure. Without a steady blood supply, the brain will be damaged beyond repair after only a few minutes. In 1908, doctors Alexis Carrel and Charles Guthrie attempted the first head transplant when they attached the severed upper body of a dog to another dog’s neck. The head section of the dog was without blood for about twenty minutes before it was connected to the blood flow of the other dog. Although the severed portion showed reflex movements, the animal had to be put down after a few hours. In the 1950s, Soviet surgeon Vladimir Demikhov performed similar experiments. He was able to improve the method of connecting the blood vessels of one dog’s upper body to the vessels in another dog. His subjects were able to move and even drink water; however, most died within days from an immune system rejection. The longest any dog survived was twenty-nine days.

These rather gruesome experiments were not true transplants as they created, in effect, two-headed dogs. In 1970, American neurosurgeon Robert White attempted to transplant the head of a monkey onto the headless body of another. White succeeded at connecting the complicated bundle of blood vessels and nerves between the monkeys, but the ability to reconnect the spine and spinal cord was medically impossible at the time. While this allowed the brain to function and survive, the monkey needed mechanical breathing support and remained paralyzed. The animal lived for eight days before its immune system rejected the transplant and the monkey died.

With advances in modern medicine, surgeons have made great strides in maintaining blood flow and keeping organs viable outside the body during transplantation. However, successfully fusing the spinal cord of a human head to another body seemed to be too large an obstacle to overcome. However, in 2013, Italian neurosurgeon Sergio Canavero published a paper claiming to have solved the problem. He called his procedure HEAVEN, for “head anastomosis venture.” Anastomosis is a medical term for the surgical connection of blood vessels or other tube-like structures in the body. In a 2015 paper, he gave further details of the process.

Canavero proposed severing the head with an ultra-sharp instrument to produce an extremely clean cut. Both the head and body would be cooled to slow the metabolic process and limit cell damage from loss of oxygen. Spinal fusion would be accomplished through electrical stimulation and the use of a plastic substance called polyethylene glycol. Early experiments in animals have shown promise that this method could aid in spinal cord repair. The subject would be given large doses of immunosuppressant drugs and would be kept in a medically induced coma for weeks after the procedure. In 2015, Canavero claimed that he could perform the surgery in two years and even had a physically disabled person volunteer to be the first subject. In 2017, Canavero said he successfully used the transplant method on a corpse in China and that the first transplant on a living human was “imminent.”

Many in the medical community doubt Canavero’s procedure is possible. They believe reconnecting the human spinal cord is still too complicated to be accomplished safely. The risk of the body rejecting the new head would be so incredibly high that any transplant would almost certainly prove fatal eventually. Another possible drawback is that there is no guarantee the electrochemical signals the brain uses to communicate with the body would be compatible in its new “environment.” This may cause the transplant recipient to experience severe disruptions in his or her mental processes.

Even a successful head transplant has medical ethicists concerned. The process could allow paralyzed people to walk or terminally ill patients to receive a new body with healthy organs; however, using an entire body to save one person may not outweigh using its organs to save many. The procedure also has implications for the human species, as repeated head transplants could result in a type of immortality. In 2019, Canavero's volunteer for head transplant surgery backed out of the procedure after getting married and having a child. By 2022, Canavero had claimed that science had reached the point that a successful head transplant was feasible and, in some cases, desirable. For example, an elderly person whose brain was sharp but whose body was deteriorating might benefit from having their brain transplanted into a younger body.

Bibliography

Canavero, Sergio. Head Transplantation: And the Quest for Immortality. CreateSpace Independent Publishing, 2014.

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Engelhaupt, Erika. “Human Head Transplant Proposed—How Did We Get Here?” National Geographic, 5 May 2015, www.nationalgeographic.com/science/phenomena/2015/05/05/human-head-transplant-proposed-how-did-we-get-here/?user.testname=none. Accessed 23 Oct. 2018.

Feltman, Rachel. “No, There Has Not Been a Successful Human Head Transplant.” Popular Science, 17 Nov. 2017, www.popsci.com/first-head-transplant-human-surgery. Accessed 23 Oct. 2018.

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Lamba, Nayan, et al. “The History of Head Transplantation: A Review.” Acta Neurochirurgica, vol. 158, no. 12, 2016, pp. 2239–47.

Peters, Brandon. "Head Transplant: Is It Possible and How Is It Performed?" Verywell Health, 27 June 2024, www.verywellhealth.com/head-transplant-4801452. Accessed 7 Nov. 2024.

Pultarova, Tereza. “Why Human Head Transplants Will Never Work.” Live Science, 20 Nov. 2017, www.livescience.com/60987-human-head-transplants-will-never-work.html. Accessed 23 Oct. 2018.

“Transplant Rejection.” US National Library of Medicine, 1 Oct. 2018, medlineplus.gov/ency/article/000815.htm. Accessed 23 Oct. 2018.