Two surgeons based in China say such surgery is “imminent.”
Recently, the media has been abuzz with news that Sergio Canavero of Italy and his colleague Xiaoping Ren of China plan to transplant a human head from a living person onto a donor cadaver. The two surgeons — who portray themselves as pioneers defying a stodgy medical establishment but are considered reckless renegades by many peers — say the head donor will be someone with a degenerative disease, whose body is wasting away while his or her mind remains active.
The body donor, meanwhile, will likely be a someone who died of severe head trauma but whose body was left unscathed. The researchers claim to have been perfecting the technique on mice, a dog, a monkey, and, recently, a human cadaver. Originally, they predicted a fall 2017 transplant but now just say it is “imminent.”
Canavero has moved the intended surgery to China because no American or European institute would permit such an operation. “Western bioethicists needed to stop patronizing the world,” he told the South China Morning Post. In contrast, he suggested, “Chinese President Xi Jinping wants to restore China to greatness” by providing a home for such cutting-edge work.
The announcement has been met with significant skepticism, to put it mildly. The implausible claims and radical proposed operation deserves “not headlines but only contempt and condemnation,” wrote Arthur L. Caplan, head of the division of medical ethics at the New York University School of Medicine, in the Chicago Tribune in December.
Critics cite the lack of adequate preliminary and animal studies, the absence of published literature on the techniques and their outcomes, the unexplored ethical problems, and the circus-like atmosphere encouraged by Canavero. Many are also understandably worried about the source of the cadaver — China has a troubling history of using executed prisoners as their body supply for transplants.
Some bioethicists argue we should simply ignore this subject, lest we contribute to the circus. A few made precisely that point in a recent special issue of the American Journal of Bioethics Neuroscience, which I edit, devoted to head transplants. One writer argued for dropping the discussion, henceforth, in favor of “discourse that actually affects people’s lives not just fuels ghoulish fantasies.”
But I disagree that bioethicists should ignore head transplants. Perhaps Canavero and Ren will not succeed in attempting a live head transplant this time around, yet they will undoubtedly not be the last to try, which makes it important to consider the ethical implications of such an attempt.
It is undeniable that the joining of a new head and body raises intriguing questions of personal identity, legal and social definitions of selfhood, and questions about the limits of science and medicine.
Canavero and Ren present head-body transplants as a natural next step in the story of transplant success. And indeed, the arc of that story has been remarkable: People have now been living for years with donated hearts, lungs, livers, kidneys, and other internal organs.
2017 marked the anniversary of the oldest living kidney transplant, given from a father to his daughter; both are alive and healthy 50 years later. More recently, we have seen successfully transplanted hands, arms, legs, and faces. The first fully successful penis transplantation occurred in 2014, as did the first live birth from a woman with a transplanted uterus.
But while face or penis transplants are difficult (many still fail), a head-body transplant presents a whole new world of complexity.
Basic scientific concerns
Canavero and Ren have published experiments with transplanting mouse heads onto rat bodies. The test animals experienced high failure rates: In one study, of 60 rats in the initial sample, only 14 mice seemed to have survived longer than 36 hours. The surgeons also claim to have successfully tested the transplant technique, by re-fusing severed spinal cords in a dog and a monkey, but they have published scant reliable evidence of those experiments or sufficient data about the outcomes.
Canavero and Ren have claimed in news reports that the dog and monkey regained movement, but there are no peer-reviewed articles and no indications they regained self-consciousness or could feel sensation. Some gruesome still pictures of a monkey with sutures around his neck have been circulated, but that is not reliable evidence.
This is not how science ought to proceed. Peer review and animal studies are there to protect patients and to double-check reported outcomes and safety. The two surgeons —who call their project HEAVEN (an acronym for “head anastomosis venture”) — have not come close to offering evidence that head transplants are safe or effective.
The key obstacle to a head transplant is the restoration of connections in the spinal cord. We all know the devastating results of broken backs and crushed spines. In a head transplant, the spinal cord is intentionally severed, and the astonishing advance claimed by Canavero and his colleagues — but, again, not proved — is that they can restore that function to a large degree. They claim to be able to do this through a two-part method: First, they make a very sharp cut that minimizes damage of the cord, and second, they use “fusogens,” chemicals that accelerate the process of re-fusing severed neurons.
However, even Canavero admits that when they reattach the spinal cord, as little as 10 to 15 percent of the nerves are actually restored. Canavero insists that his animals regain some movement. But even if that’s true, the spinal cord is also the conduit for sensation, proprioception (knowing where we are relative to the space around us), pain, etc. He has published no evidence that these sensations are restored.
Who would the person that emerges from such a surgery really be?
Some say the odds of success are so low that an attempt at a head transplant would amount to murder. But even if it were feasible, even if we could put a head and a body together and have a living human being at …read more