It may sound like something from Mary Shelley's Frankenstein, but the possibility of the world's first human head transplant is very real. In December 2017, Italian neuroscientist Dr. Sergio Canavero plans to perform the procedure alongside a team of Chinese surgeons, led by Dr. Xiaoping Ren - who to date, has performed around 1,000 head transplants on mice.
The procedure - named HEAVEN-GEMINI - will take around 150 surgeons and nurses approximately 36 hours to complete and will cost around $11 million.
Dr. Canavero, of the Turin Advanced Neuromodulation Group (TANG) in Italy, first announced his proposal for the HEAVEN-GEMINI project back in July 2013.
Unsurprisingly, his proposal has been met with much criticism, with some scientists branding Dr. Canavero as "nuts."
However, Dr. Canavero is not the first surgeon to delve into the world of head transplants. In 1970, the late American neurosurgeon Dr. Robert White was the first to transplant a monkey's head onto another monkey's body.
While the recipient monkey had the ability to see, hear, taste and smell following the procedure, lack of sufficient technology meant the animal's spinal cord nerves were not properly fused to its head, leaving it paralyzed. In addition, the animal's immune system rejected the donor head, causing it to die 9 days later.
While Dr. Canavero admits that spinal cord fusion (SCF) and the possibility of head rejection are still key challenges for the HEAVEN-GEMINI project, he claims that recent animal studies indicate they can be overcome.
"The greatest technical hurdle to such endeavor is of course the reconnection of the donor's and recipient's spinal cords. It is my contention that the technology only now exists for such linkage," he said in a paper published in Surgical Neurology International.
Even if the procedure itself is feasible - as Dr. Canavero believes - some questions remain: what would be the benefits of a head transplant? And is the body able to fully recover from such a traumatic event? Medical News Today spoke to Dr. Canavero to get some answers.
Removing a healthy head from a 'body without hope'
"We're going to remove one head under deep hypothermia and reinstall it on a new body. Of course, we are talking about a head with a perfectly healthy brain, but with an alien body - so a body without hope," Dr. Canavero told MNT.
Both the recipient's head and donor body will be put into hypothermia mode for around 45 minutes in order to limit any neurological damage that may occur from oxygen deprivation.
The head will be removed from the donor body using an "ultra-sharp blade" in order to minimize spinal cord damage - a process the Italian surgeon says is key for successful SCF.
Then comes the trickiest part: attaching the recipient's head to the donor body, which involves the complex SCF process. In his original paper, Dr. Canavero explained that the chemicals polyethylene glycol or chitosan will be utilized to encourage the fusion, before the muscles and blood supply are sutured.
While many scientists have raised concerns about the feasibility of the SCF process, Dr. Canavero told MNT that he is not worried.
"The possibility of fusing a spinal cord has already been achieved 50 years ago," he said. "What is incredible is that no one took any notice at the time because the guy who really pulled it off was an American functional neurosurgeon who made this incredible, astounding observation that whenever you cut the spinal cord with a minimally traumatic severance and you wait long enough - that's the trick, not 1 day, not 1 week, not 1 month, but several months - then animals start reworking."
"As far as SCF is concerned, with the data, we're already there," he added. "And what really accrued over the past 50 years, which has been lost incredibly up until now, will simply help us accelerate the process - nothing more and nothing less."
After surgery, the recipient will be placed in a coma for 3-4 weeks. This is to ensure neck movement is avoided, allowing time for the new nerve connections to fuse together.
During the coma period, the recipient will also be subject to electrical stimulation through implanted electrodes; it is hoped this will give SCF a boost.
Head transplant 'is a failure of medicine'
The words "body without hope" are central to the reasons behind the HEAVEN-GEMINI project; it aims to help people who have untreatable neurological or muscle-wasting diseases that have left them completely paralyzed from the neck down.
If successful in curing such conditions, one might hail head transplantation as a medical breakthrough, but Dr. Canavero told MNT that he perceives the procedure in another light:
"It will be about curing incurable neurological disorders for which other treatments have failed big time, so gene therapy, stem cells - they all just came to nothing. We have failed despite billions of dollars being poured into this sort of research.
So actually, head transplant or body transplant, whatever your angle is, is actually a failure of medicine. It is not a brilliant success, a brilliant advancement to medical science. When you just haven't tackled biology, you don't know how to treat genes, you don't really understand, and you really need to resort to a body transplant, it means that you've failed. So this must not be construed as a success of medical research."
Still, there is no doubt that if the procedure works, it could potentially help people all over the globe who are living with paralysis. And one individual who firmly believes this is 30-year-old Russian man Valery Spiridonov.
First head transplant to take place in China
Back in June, MNT reported that Spiridonov will be the first person to undergo a head transplant.
Spiridonov has a rare genetic condition called Werdnig-Hoffman disease - a form of spinal muscular atrophy (SMA1). The disease is caused by loss of motor neurons in the spinal cord and brainstem, leading to loss of muscle control.
"I can hardly control my body now. I need help every day, every minute," Spiridonov told MailOnline earlier this year. "I am now 30 years old, although people rarely live to more than 20 with this disease."
While Spiridonov admitted he is concerned about the risks of the operation, he believes his participation in Dr. Canavero's project could not only change his life for the better, but also the lives of others who are living with paralysis.
"The operation is aimed at restoring independence to the severely disabled," he told ITV News last month. "If it is successful, it will help thousands who are in an even more deplorable state than me in the future."
Spiridonov talks more about his decision to undergo the procedure in the video below:
Despite previous reports, however, Dr. Canavero told MNT that although he is confident Spiridonov will undergo head transplantation, he will now not be the first subject.
"On August 27th, China and me initialed a contract - a cooperation program that will lead straight to the first head transplant in China sometime toward the end of 2017, if everything goes according to plan," Dr. Canavero told MNT.
"Unfortunately the Chinese program has no place for Valery," he added. "The Chinese are not going to transplant a Russian, they are going to transplant a Chinese person."
The Chinese program will be led by controversial surgeon Dr. Xiaoping Ren, of Harbin Medical University in China. Dr. Ren has already conducted around 1,000 head transplants on mice, and he has perviously expressed his desire to carry out the procedure on humans.
"Dr. Xiaoping Ren is a very smart and talented surgeon," Dr. Canavero told us. "Now, the problem in China and for Xiaoping Ren is finding a suitable place in China to do the procedure. There are places in China that would like to be involved, so it is up to the Chinese to work this out."Dr. Ren has not yet revealed any information about who the Chinese recipient might be.
'If no critics step forward, you're saying nothing special'
As well as securing a contract for the procedure in China - with strong prospects in Russia for the surgery to be performed on Spiridonov - the project has now received support from the US, in the form of Mayo Clinic's Dr. Michael Sarr, who is chief editor of the journal Surgery.
"I am happy to say that Michael Sarr has sponsored our project - we will have a mini symposium early next year with all the science involved and details," Dr. Canavero told us.
But despite the project gaining momentum, it is safe to say that it continues to attract criticism.
"This is such an overwhelming project, the possibility of it happening is very unlikely," Harry Goldsmith, a clinical professor of neurological surgery at the University of California-Davis, told New Scientist earlier this year. "I don't believe it will ever work, there are too many problems with the procedure. Trying to keep someone healthy in a coma for 4 weeks - it's not going to happen."
But Dr. Canavero said he welcomes such criticism, noting that it drives his work forward:
"The world is moving, the critics are dwindling. Of course, there will always be critics. Science teaches us that when you propose something groundbreaking, you must be confronted by criticism. If no critics really step forward, you are saying nothing special."
The ethical concerns
A number of ethical concerns have also been raised regarding the procedure - in particular, about how the body and brain will recover after the operation.
"If you put a new head on the body, you are likely to create someone who is insane because the neural inputs - the chemistry - will be completely different," Arthur Caplan, of the Division of Ethics at the NYU Langone Medical Center in New York, NY, wrote in a commentary in May.
"The brain would be completely confused," he added. "Not only would it be unethical because we don't have the science, it would be unethical to even think about this because of the significant risk of creating someone who would be insane, demented or tortured."
Dr. Canavero told MNT that he is not concerned about the safety of the brain during or after the procedure:
"The experience is there and it tells us it is feasible. You can really protect the brain, Dr. White already did it on monkeys, but the same technology - with some adaptations, of course - has been time and time again tested in human patients, so I am not concerned about that. Plus, the donor recipients are separated no more than 2.5 meters, and it takes just a few seconds to remove the head once it is detached onto the body."
When it comes to the brain adapting to a new body, Dr. Canavero claims there is a significant amount of evidence suggesting this is possible.
"I am pretty sure the brain has the capacity to adapt and to fit into the new body by remapping and rewiring; we have plenty of evidence that it is feasible," he told us. "Plus, the patient will be submitted to immersive virtual reality, which is a way to recreate in the brain this image of a whole body. We already have the experience, the feel of how it is to be in a whole moving body."
'We are not just concocting this in some secret Frankenstein lab'
It goes without saying that up until the point when the world's first head transplant is performed - and even after - the procedure will be a topic of much debate.
Will the procedure cure thousands of people from paralysis? Or will it go down in history as a failed attempt by someone whom others claim to be a "crazy" scientist? Only time will tell.
However, Dr. Canavero is confident that in just over 2 years from now, he and his Chinese colleagues will have completed the world's first ever human head transplant:
"It will be a success. There is a step-by-step, no-risk approach to all this. If step one doesn't pan out, we will work more on that step until it works, move on and so on.
There is a detailed plan - we are not just concocting this in some secret Frankenstein lab. We are way ahead now into the project, everything is moving - it is no longer science fiction."