"I'm a very open person to new ideas; I would love to be able to talk to him," Lee said. "But there are some things that are more ... far-fetched ... than others."
Before the surgery could move from Star Trek to real life, several things would have to happen. For example, surgeons have been doing various transplants for over 100 years and still have not completely solved the problem of organ rejection.
Of the 100 or so hand transplants that have been performed worldwide, Lee said, there have been a "tremendous number of complications," and some have had amputations.
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Spinal cord injuries continue to frustrate leading doctors in the field. The spinal cord regenerates at a rate of 1 millimeter a day, Lee points out. "So if you take a rule and measure from your neck to your hands, it would take years before body parts would begin to function." That is, IF it were possible to fuse the spinal cord, and IF the body didn't reject the head.
Assuming the issues of transplant rejection and regenerating the spinal cord could be solved, protocol calls for perfecting the surgery in much simpler animals first.
Canavero points to the 1970 transplant of a monkey's head, but that surgery resulted in a monkey that lived, paralyzed, for nine days before its immune system rejected the head. There was no attempt to join the spinal cords. Amphibians have an easier time regrowing the spinal cord, but it's much trickier in mammals.
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"You can't stick the ends together and expect them to work," said Dr. Peter Nakaji, a neurosurgeon at the Barrow Neurological Institute in Phoenix. "Imagine taking a bundle of hair and then attempting to squash it back together to find the original hair it came from. Even if they could, the chance of them hooking up in the right places is not just 1 in a billion, it's 1 in a zillion billion."
But is there a time in the future when some machine might be able to stitch or meld the right nerves back together?
"It's not beyond belief, but it's not anytime in our lifetime," Nakaji said. "I'm all in favor of the big dream; that's how we move forward. I wouldn't want to be one of the people making fun of the Wright brothers. The time may come when we have the technology to do such things."
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Canavero has also compared the surgery to the first flight.
"I agree with the critics, this first one will be more like Kitty Hawk than a Boeing 747," Canavero told Motherboard. "Then it will be streamlined, perfected. It'll be faster, you won't need 150 persons, it won't last 36 hours, it'll be done in a hospital next to your building."
The motivation is there, Nakaji said.
"Will there be a future in which we could swap people around in bodies?" Nakaji said. "It raises the question of who we are, and some very science fiction-y type questions that we don't know the answers to. But It's interesting to think about the other crazy ideas that could happen in the future."