A head transplant or full body transplant is an experimental surgical operation involving the grafting of one organism's head onto the body of another. In many experiments, the recipient's head has not been removed, but in others it has been. Experimentation in animals began in the early 1900s. As of 2026, no lasting successes have been achieved.
Medical challenges There are three main technical challenges. As with any organ transplant, managing the immune response to avoid transplant rejection is necessary. Also, the brain is highly dependent on continuous flow of blood to provide oxygen and nutrients and remove waste products, with damage setting in quickly at normal temperatures when blood flow is cut off. Finally, managing the nervous systems in both the body and the head is essential, in several ways. The autonomic nervous system controls essential functions like breathing and the heart beating and is governed largely by the brain stem; if the recipient body's head is removed this can no longer function. Additionally each nerve coming out of the head via the spinal cord needs to be connected to the putatively corresponding nerve in the recipient body's spinal cord in order for the brain to control movement and receive sensory information. The risk of systematic neuropathic pain is high and as of 2017 had largely been unaddressed in research. Of these challenges, dealing with blood supply and transplant rejection have been addressed in the field of transplant medicine generally, making transplantation of several types of organs fairly routine; however, as of 2017 in a field as common as liver transplantation around a quarter of organs are rejected within the first year and overall mortality is still much higher than the general population. The challenge of grafting the nervous system remained in early stages of research as of 2017.
History
Alexis Carrel was a French surgeon who had developed improved surgical methods to connect blood vessels in the context of organ transplantation. In 1908, he collaborated with the American Charles Claude Guthrie to attempt to graft the head of one dog on an intact second dog; the grafted head showed some reflexes early on but deteriorated quickly and the animal was killed after a few hours. Carrel's work on organ transplantation later earned a Nobel Prize; Guthrie was probably excluded because of this controversial work on head transplantation. In 1954, Vladimir Demikhov, a Soviet surgeon who had done important work to improve coronary bypass surgery, performed an experiment in which he grafted a dog's head and upper body including the front legs, onto another dog; the effort was focused on how to provide blood supply to the donor head and upper body and not on grafting the nervous systems. The dogs generally survived a few days; one survived 29 days. The grafted body parts were able to move and react to stimulus. The animals died due to transplant rejection. In the 1950s and '60s, immunosuppressive drugs and organ transplantation techniques were developed that eventually made transplantation of kidneys, livers, and other organs standard medical procedures. In 1965, Robert J. White did a series of experiments in which he attempted to graft only the vascular system of isolated dog brains onto existing dogs, to learn how to manage this challenge. He monitored brain activity with EEG and also monitored metabolism, and showed that he could maintain high levels of brain activity and metabolism by avoiding any break in the blood supply. The animals survived between 6 hours and 2 days. In 1970, he did four experiments in which he cut the head off of a monkey and connected the blood vessels of another monkey head to it; he did not attempt to connect the nervous systems. White used deep hypothermia to protect the brains during the times when they were cut off from blood during procedure. The recipient bodies had to be kept alive with mechanical ventilation and drugs to stimulate the heart. The grafted heads were able to function - the eyes tracked moving objects and it could chew and swallow. There were problems with the grafting of blood vessels that led to blood clots forming, and White used high doses of immunosuppressive drugs that had severe side effects; the animals died between 6 hours and 3 days after the heads were engrafted. These experiments were reported and criticized in the media and were considered barbaric by animal rights activists. There were few animal experiments on head transplantation for many years after this. In 2012, Xiaoping Ren published work in which he grafted the head of a mouse onto another mouse's body; again the focus was on how to avoid harm from the loss of blood supply; with his protocol the grafted heads survived up to six months. In 2013, Sergio Canavero published a protocol that he said would make human head transplantation possible. In 2016, he announced his plans to do the procedure on Valeriy Spiridonov, a disabled Russian software engineer suffering from spinal muscular atrophy, who volunteered for the surgery. Canavero claimed that there was a 90% chance of success. In the proposed procedure, a body would be donated from a brain-dead living patient. However, Spiridonov later cancelled his participation after getting married and having his first child. In 2015, Ren published work in which he cut off the heads of mice but left the brain stem in place, and then connected the vasculature of the donor head to the recipient body; this work was an effort to address whether it was possible to keep the body of the recipient animal alive without life support. All prior experimental work that involved removing the recipient body's head had cut the head off lower down, just below the second bone in the spinal column. Ren also used moderate hypothermia to protect the brains during the procedure. In 2016, Ren and Canavero published a review of attempted as well as possible neuroprotection strategies that they said should be researched for potential use in a head transplantation procedure; they discussed various protocols for connecting the vasculature, the use of various levels of hypothermia, the use of blood substitutes, and the possibility of using hydrogen sulfide as a neuroprotective agent.
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