The plan to perform a human head transplant is on track, says Sergio Canavero, after successful experiments on monkeys and mice
By Sam Wong
Scroll down to see this image. Some readers may find it upsetting
The head transplant juggernaut rolls on. Last year, maverick surgeon Sergio Canavero caused a worldwide storm when he revealed his plan to attempt a human head transplant to New Scientist. He claimed that the surgical protocol would be ready within two years and said he intended to offer the surgery as a treatment for complete paralysis.
Now, working with other scientists in China and South Korea, he claims to have moved closer to that goal with a series of experiments in animals and human cadavers.
“I would say we have plenty of data to go on,” says Canavero. “It’s important that people stop thinking this is impossible. This is absolutely possible and we’re working towards it.”
“Science through PR”
The work is described in seven papers set to be published in the journals Surgery and CNS Neuroscience & Therapeutics over the next few months. New Scientist has not seen the papers and has not been able verify the latest claims. The issue of CNS Neuroscience & Therapeutics will be guest-edited by one of Canavero’s collaborators.
“6 things you’re dying to ask about head transplants”
The fact that Canavero has gone public with the latest results before the papers are published has raised eyebrows. “It’s science through public relations,” says Arthur Caplan, a bioethicist at New York University School of Medicine. “When it gets published in a peer-reviewed journal I’ll be interested. I think the rest of it is BS.”
Thomas Cochrane, a neurologist at Harvard Medical School’s Centre for Bioethics, agrees that Canavero’s premature disclosure is unorthodox. “It’s frowned upon for good reason,” he says. “It generates excitement before excitement is warranted. It distracts people from actual work that everyone can agree has a valid foundation. As far as I can tell, that operation has mostly been about publicity rather than the production of good science.”
Although we can’t verify them, New Scientist has seen images and videos of some of the procedures Canavero describes.
hese include the video above of mice sniffing and moving their legs, apparently weeks after having the spinal cord in their necks severed and then re-fused. C-Yoon Kim, at Konkuk University School of Medicine in South Korea, who carried out the procedure, says his team have demonstrated the recovery of motor function in the forelimbs and hindlimbs of the animals. “Therefore I guess it is possible to reconnect the [spinal] cord after complete severance,” he says.
Canavero says Kim’s work shows that the spinal cord can re-fuse if it is cut cleanly in the presence of polyethylene glycol (PEG), a chemical that preserves nerve cell membranes. “These experiments prove once and for all that simply using PEG, you can see partial recovery,” he says.
As well as the use of PEG, the procedure Canavero outlines in the papers includes techniques to aid recovery such as spinal cord stimulation and the use of a negative pressure device to create a vacuum to encourage the nerves to fuse.
According to Canavero, researchers led by Xiaoping Ren at Harbin Medical University, China, have carried out a head transplant on a monkey. They connected up the blood supply between the head and the new body, but did not attempt to connect the spinal cord. Canavero says the experiment, which repeats the work of Robert White in the US in 1970, demonstrates that if the head is cooled to 15 °C, a monkey can survive the procedure without suffering brain injury.
“The monkey fully survived the procedure without any neurological injury of whatever kind,” says Canavero, adding that it was kept alive for only 20 hours after the procedure for ethical reasons. New Scientist was, however, unable to obtain further details on this experiment.
“We’ve done a pilot study testing some ideas about how to prevent injury,” says Ren, whose work is sponsored by the Chinese government. He and his team have also performed experiments on human cadavers in preparation for carrying out the surgery, he says.
Rich backers needed
Canavero is seeking funds to offer a head transplant to a 31-year-old Russian patient, Valery Spriridonov, who has a genetic muscle-wasting disease. Canavero says he intends to make a plea to Mark Zuckerberg to finance the surgery. Last week, Trinh Hong Son, director of the Vietnam-Germany Hospital in Hanoi, Vietnam, offered to host the procedure.
“If the so-called head transplant works, this is going to open up a whole new science of spinal cord trauma reconstruction,” says Michael Sarr, editor of the journal Surgery and a surgeon at the Mayo Clinic in Rochester, Minnesota. “We are most interested in spinal cord reconstruction using head transplantation as a proof of principle. Our journal does not necessarily support head transplantation because of multiple ethical issues and multiple considerations of informed consent and the possibility of negative consequences of a head transplant.”
Against the odds
Caplan says Canavero should study nerve regrowth with PEG in people with spinal cord injury before attempting a head transplant. “There are hundreds of thousands of people who could benefit from something that would regrow the spinal cord. It’s like saying I want to fly to the next galaxy when it would be nice to set up a colony on Mars, and I think about the same odds.”
Nevertheless, Canavero believes head transplantation is the only treatment that will work for paralysed patients. “Gene therapy has failed. Stem cells, we’re still waiting. Even if they come now, for these patients there is no hope. Tetraplegia can only be cured with this. Long term, the body decays, organs decay. You have to give them a new body because even if you take care of the cord, you’re going nowhere.”
Read more: First human head transplant could happen in two years
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