WATCH: Surgeons Perform World’s First Head Transplant Surgery(VIDEO)
A head 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 was not removed but in others it has been. Experimentation in animals began in the early 1900s. As of 2018 no durable success had been achieved
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. Finally, 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.
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 the 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 were developed 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 objections 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 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.
In November 2017, Canavero announced that he and Ren had performed the first human head transplant on cadavers. The significance of this claimed success, involving, as it does, only mechanical reconnection of tissue in a cadaver, is disputed.
WATCH: Surgeons Perform World’s First Head Transplant Surgery
Scientists have successfully performed a head transplant on a corpse, and are ready to do it on a living person, according to the man famous for promising it.
Surgeon Sergio Canavero has become famous for claiming to be working on the first human head transplant. And he says that the successful test shows that his plans will work.
The successful transplant on the corpse shows that his newly developed techniques for re-connecting the spine, nerves and blood vessels to allow the two bodies to live together will work, he said. It also seems to suggest that the surgery could be done in the 18-hour target that the team has set itself to be successful.
He described himself as having “realised the first human head transplant”. That will allow his team to get to work doing the new head transplant “imminently”, he said.
Professor Canavero has gained fame and some notoriety for his controversial claims about the first head transplant. He has signed up his first patient, a Russian man called Valery Spiridinov who will have his head frozen and then grafted onto a new donor body, according to his doctor.”The first human transplant on human cadavers has been done,” he said. “A full head swap between brain dead organ donors is the next stage.
“And that is the final step for the formal head transplant for a medical condition which is imminent,” he told a conference in Vienna, according to The Telegraph, which first reported the news. The paper claimed that the “world’s first human head transplant” had been “successfully carried out”, though clearly that won’t really have happened until someone undergoes the procedure and survives it.
The surgeon didn’t appear to give any concrete proof for his claim, but said that would be made available in the coming days. “The first human head transplant, in the human mode, has been realised. The paper will be released in a few days. Everyone said it was impossible. But the surgery was successful,” he said, according to The Telegraph.
Professor Canavero has made repeated grand claims about his hopes for the surgery. He has said that it could happen this year, for instance, and that the surgery could even take place in the UK.
His team have made repeated claims for his success, including supposedly having successfully carried out the surgery on both rats and monkeys – as well as now on a human corpse.
But the medical community has looked at the surgery and the spectacle surrounding it with horror. Scientists have warned that the first patient could undergo something “a lot worse than death”, for instance, warning that the patient would undergo horrific suffering as they adjusted to their new body.