Full-Body Transplants Are a Crazy, Wildly Unethical Idea

For the last week, an Italian neurosurgeon has been executing a full-blown media offensive, talking up his plan to stitch one persons head to another persons body. If the powers-that-be would just get over their ethical queasiness, Sergio Canavero of the Turin Advanced Neuromodulation Group says he could accomplish the feat by 2017.

But full-body transplants arent so crazy. In fact, it might surprise you that there was a successful operation as far back as 1818. Well, successful if you ignore that the transplantee freaked out and murdered his doctors family. Oh wait. That was Frankenstein. I take it back, full body transplants are totally crazy.

What the hell, going to the moon was crazy too, right? And a maybe-crazy-but-what-the-hell moonshot is exactly how Canavero sees his plan to help patients with severe physical impairments. Why did the US and the Soviet Union just vie for being the first to space? Because it is about measuring dicks. We want to demonstrate as a country, to say: I am the best, he says. Canaveros latest paper glosses over questions of ethics and practicality and tacklesthe trickiest aspect of the head-swapping procedure: The spinal splice.

Canaveros plan focuses on sewingtwo people together by their spinal cords. (Hooking up the rest of the utilitiesblood vessels, airways, blood vesselsis incredibly difficult, but trifling in comparison.) Step one is to sever the cords with a special, ultra-thin blade. Canavero rightly notes most cases of spinal trauma are well, traumatic: Snapping your neck on a skateboard ramp is bound to leave the spinal cord in an untidy condition. Those nerve cells scar, and scarring would impede their regeneration (if cells in the central nervous system could regeneratewell get to that in a sec). A clean wound, on the other hand, heals cleanly. Canavero likens those million sharply severed neurons to spaghetti. Italians adore spaghetti, I love spaghetti, and spaghetti is what is called for here, he says.

The job of fusing those spaghetti-like spinal sections together falls to a substance called polyethylene glycol. This stuff has actually been pretty good at repairing the motor functions in rats with spinal traumathough even the kindest critic will point out that successful rat experiments are a far cry from proving that the stuff will repair human spines. Still, Canavero is raring to go. I have enough animal data, he says. Give me a brain dead organ donor. Say someone is in a traumatic car accident, and doctors say that he cannot be saved. In the time between when the persons family says its OK to pull the plug and the moment the doctors actually do so, Canavero asks for three to four hours. I sever the spinal cord, add polyethylene glycol, and start measuring electrophysiological responses, he says.

After surgery (and during it, one hopes), Canavero will keep the patient in a coma. He estimates it will take about at least two weeks for the first axons to beginlacing themselves together, at which point the patient can be revived. Throughout the coma and for some time after, Canavero will bathe the spinal splice with a mild electrical current. This is not a free Frankenstein joke from the good doctor: Its actually a method thats seen surprisingly promising results healingrealhuman patients with spinal trauma. Canavero is confident that this will keep the muscle cells operational. Combined with physical therapy, Canavero estimates his as-yet-unchosen patient (any volunteers?) will be back on her (new) feet in about a year.

In case this wasnt entirelyclear: Canaveros plan is insane. Like, James Bond villain insane. And its not just because his plan fits together like a Voltron of bad science (which it does). Its kind of a bummer, actually, because his plan couldmaybework, if he was given free rein to cut and sew living peoples heads to dead peoples bodies until he got it right. But besides ethics, theres an unfortunate fact of biology standing in his way: The central nervous system in higher vertebrateslike humansdoes not regenerate. Hes insane. You cant put a head on somebody else! says Binhai Zhang, a neurosurgeon at UC San Diego. The reason why goes down to your DNA. The genes in a mature mammalian central nervous system that control regeneration are repressed, says Michael Beattie, a professor of neurosurgery at UC San Francisco. Theyll stay that way, no matter how much you treat the spinal cord with polyethylene glycol and electrical currents. (Although, hey, who wants to work on un-repressing those genes?)

Nobody knows for sure why the cells in your brain and spine arent wired for regrowth. After all, your peripheral nervous systemthe circuitry for every other part of your bodyconducts electrical impulses in exactly the same way, but its genes can code for self-repair. Beattie says this may have to do the fact the spine and brain contain the circuitry coded for movement, not just for conducting signals. Spinal cells must knit themselves together in super-complex configurations in order to command the motor functions youve learned over a lifetime. Once the connections are made, you dont want the wrong connections getting created, he says.

The only reliable way to induce spinal cell regrowth in higher order vertebrates is with stem cell therapy. Last year scientists showed pluripotent stem cells could regrow damaged spinal cordsbut only in rats. Mark Tuszynski studies stem cells in spinal injury at UC San Diego, and he says even with this advance the research community is years away from attempting suchtreatments on humans. Its not at the stage yet where there can be meaningful advances in clinical trials, he says. Plus stem cells will need help, in the form of drugs that knock down natural regeneration inhibitors that your body creates (because cancer), and still more drugs to keep your body from creating scar tissue around the wound. (Though in fairness, thats the idea behind Canaveros super-thin knife.) All of this research remainsyears away from clinical application.

And this slow, careful tempodo no harm being a hallmark of western medicineis what drives Canaveros bold assertion that he will have a successful head transplant in 24 months. There are all these people who tell you: Who is this guy who can do this in two years? When you go public with something like this, you have to have two balls like this. There are people who are not so strong-balled and will just get crushed by the critics. But I love the critics. This is a feat of theoretical neuroscience and the evidence is there and its going to work. In case you need clarification, his main argument there is Haters gonna hate.

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Full-Body Transplants Are a Crazy, Wildly Unethical Idea