One reason why I write for this newsletter is that I want to make neuroscience capture the public imagination. Sometimes, though, that happens in aggravating ways. Often when I get started people interrupt impatiently: “Yeah, that’s interesting,” they say, “but have you heard about the guy that’s going to have a head transplant?” And then I think to myself “Yeah… what about him?”.
“The guy” in question is Valery Spirindov, a 31-year-old Russian entrepreneur with a terminal neurodegenerative condition called Werdning-Hoffman disease that has been systemically destroying his motor neurons. Valery’s single-minded intent to save his own life brought him into contact with one of the world’s leading experts in transplantation medicine. Dr. Xiaoping Ren currently runs a lab at Harbin Medical University, where his team specializes in severing spinal cords and transplanting heads in mice. In several of his papers, it was reported that 22% of animals survived the procedure for more than two hours [1]. In fact, they seemed to regain some bodily function, and were able to eat, drink, and move clumsily around their cages.
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| Head transplant gummy bears, ellajphillips via Flickr |
Fringe Science or Calculated Risk?
However, Ren’s findings have recently jumped from relatively minor journals to tabloid coverage, as it was revealed last year that he had transplanted the head of a macaque. It survived for an indeterminate amount of time and, according to Ren and others, demonstrated promising motor activity (including biting). A reporter who was shown the “after” videos drily reported that the animal didn’t appear to do much at all, apart from blinking when it was poked in the eye with forceps [2].
TRANSPLANTED MACAQUE HEAD MOVES, AND BITES!
Part of the reason why head transplantation procedures have been gaining momentum (and media attention) is due to Ren’s partner, Italian neurosurgeon Sergio Canavero. Canavero, in many ways, has been a loud advocate of the procedure, in Spirindov’s case boasting that the surgery would have a “90 percent plus” chance of success [2]. Together with Ren, he is a core member of HEAVEN, the head anastomosis venture project with the rather spectacular plan to sketch out a procedure for “total cephalic exchange in man” [3].
Transplant On the Table
First, the surgery requires one extremely important ingredient: a “donor”. In Spirindov’s case, this will likely be a young male victim of an accident causing brain death. After getting consent from family members, this unfortunate individual would be brought into an operating theatre alongside Spirindov. The latter would be anesthetized, and cooled to 10 degrees Celsius [3]. Such therapeutic hypothermia has been shown to have neuroprotective effects [4], but only to a point. The doctors theorize that after this temperature is achieved, the team would have one hour to move the head without causing irreversible damage.
So away they will go. Both men will be simultaneously decapitated using the GEMINI procedure, developed by Canavero and others. Essentially, the spinal cord is severed using a diamond-coated microblade, while the environment is perfused with polyethelyne glycol, a chemical that causes cell bodies to fuse and ideally lessen degeneration [1,3,5]. In an image truly delightful to contemplate, The Atlantic reports that Canavero plans to have the head “float across the operating theater to the donor body on a customized crane, hanging by Velcro straps.” [2]. The two spinal cord remnants would then be aligned, doused with more polyethelyne glycol and administered electrical shocks, also thought to aid in preventing nerve damage [3,6]. From there, the surgery is mostly mechanical, albeit nightmarishly so. First, blood vessels, then esophagus, trachea and muscles. Easy peasy.
Even if it "mechanically" works, I (and the rest of the medical establishment) have some serious questions. The brain is stunningly plastic, even in adulthood, but expecting a brain to communicate with an entirely new peripheral nervous system is a lot to ask. Even if autonomic functions like breathing and heartbeat regulation are successful, what about sensation? What about motor control? Mr. Sprindov hasn’t walked since infancy. And what about organ rejection (more technically, which half will be rejecting the other)? Will Spirindov ever feel “at home” in his new body?
The Verdict
I am clearly not an an expert in any field of the 80+ member team trying to make this surgery happen. There is a lot of expertise being poured into this undertaking, second only to the amount of good will in the project. But as much as I hope for Mr. Sprindov’s sake that he will walk away from this a changed man (in every literal sense), I do not think it will work. I think that Ren and Canavero are really onto something - their techniques are based on decades of work in transplant medicine, and are hardly as Frankensteinian as most stories might have you believe. But their uniqueness is part of the problem.
Their published works are a veritable net of self-citation, and most other experts who weigh in do so from their scientific armchairs. Given the ethical implications, it’s understandable why more scientists don’t want to work on head transplantation. But I believe that participation from a wider scientific community would exponentially increase the team’s odds of success, while bringing some more accountability to its more outlandish claims.
However, despite all of the bombast and exaggeration flying around this news story, I still have to commend everyone involved for getting people legitimately excited (both on biological and ethical standpoints). I plan on following how the story plays out in the coming year, and will be reporting on the eventual outcome right here. Stay tuned.
by Constance Holman, PhD Student AG Schmitz
This article originally appeared in CNS Volume 9, Issue 4, From Cradle to Grave in the Brain
[1] Ren et al., CNS Neurosci. Ther. 2014
[2] Kean, The Atlantic 2016
[3] Canavero, Surg Neurol Int 2013
[4] Karnatovskaia et al., Neurohospitalist., 2014
[5] Borgens, Neurosurgery 2001
[6] Gordon et al. Int Rev Neurobiol, 2009
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