In the 1970s, a surgeon from Ohio transplanted the heads of rhesus monkeys onto new bodies. They survived and could even eat and follow objects with their eyes. But the doctor hadn’t reconnected their spinal cords, so they remained paralyzed.
Canavero and Ren have different plans.
They hope to fuse the nerves cells of the head and body using a gluelike chemical called polyethylene glycol.
Ren has already tested this chemical on mice with spinal cords that have been severed. The mice were walking within two days of the procedure.
In preparation for Spiridonov’s surgery next year, Ren’s team has also successfully transplanted a mouse’s head onto another body. This was later repeated on a monkey.
These animals, though, were euthanized within a day of the procedure. So future experiments are needed in order to know if a head transplant is a long-term solution.
Extremely risky procedure
According to The Atlantic, Canavero says there is a “90 percent plus” chance of success. Ren, though, is less definite about the outcome.
And as with all transplant surgeries, there are many risks.
Before Patrick Hardison underwent one of the world’s most extensive face transplants, doctors gave him a 50 percent chance of survival.
Infection, loss of blood flow to the transplanted organ, and rejection of the new tissue all lower the odds of success.
With a head transplant, loss of blood flow to the brain is an even larger problem. Lack of oxygen can damage the brain and leave a person with severe mental deficiencies.
Cooling both the head and body before and during surgery could allow the cells to survive longer without oxygen. Still, doctors would only have an hour or less to complete the surgery.
One of the most common risks of organ transplants is tissue rejection. With a head transplant, though, it would be the head that would be seen as “foreign” by the new body’s immune system.
Finding a donor body that is a good match for Spiridonov — in this case a male who died of head trauma with no damage to the body — could minimize this risk.
But he would need to take powerful immunosuppressive medications for the rest of his life to limit the chance that the new body’s immune system would attack the tissues of his head.
After surgery, Spiridonov would be kept in a coma for several weeks to allow his spinal nerves to heal.
But if he wakes up before his spinal nerves heal, there is a chance that he would be paralyzed. Or that his nerve cells would fuse incorrectly — with nerves meant to control the arms connected to the legs instead.
In spite of that, Spiridonov is still willing to face those odds.
His genetic condition, known as Werdnig-Hoffmann disease, has left him confined to a wheelchair. He movements are limited to typing, feeding himself, and steering his wheelchair with a joystick.
Werdnig-Hoffmann disease is also fatal, although Spiridonov has already lived longer than his doctors had expected.
Crossing an ethical line
The fringe nature of Canavero’s and Ren’s plans has led to harsh backlash from scientists and ethicists.
Some have called it “nuts” or scientifically impossible.
Others are concerned that even though Spiridonov is aware of the risks, it still doesn’t make it OK for doctors to perform the surgery.
And then there is the cost — between $10 million and $100 million.
Would this money be better spent on helping the thousands of people who suffer spinal cord injuries each year?
Head transplants also raise issues of who the new body belongs to, especially in terms of its sperm or eggs.
If someone with a new body had a child, would the family of the donated body have visitation rights?
And then there are the more philosophical questions. What does it mean for a person’s sense of self to have a body that they weren’t born with?
There’s not even certainty that someone would be able to accept a new body as part of themselves.
The man who underwent the world’s first hand transplant was uncomfortable with his new hand. So he stopped taking his immunosuppressive drugs and the hand had to be removed.
Public angst about head transplants may subside after a few successful surgeries, the way it has with face transplants.
But for now, Canavero and Ren are still working on the other side of a line that many think we shouldn’t cross.