A HUMAN HEAD TRANSPLANT IS POSSIBLE, BUT. . .
Earlier this year, an Italian neurosurgeon made headlines when he claimed that he would perform the first human head transplant by 2017. Dr. Sergio Canavero has since found a willing participant in Valery Spiridonov, a Russian man with an incurable muscle-atrophy disease. But is the procedure medically — or ethically — possible? We asked experts to weigh in:
Victor Yang, neurosurgeon and senior scientist at Sunnybrook Health Sciences Centre:
“We have to tackle at least two types of problems. One is an immunological problem, where we constantly have organ rejections, and patients need to be on immunosuppressant drugs to make sure they don’t reject the organ. . . . The second difficulty I think is even harder. The brain stem and spinal cord are very high-density fibre tracts, where a lot of connections are made. Making the correct connections from one axon to another axon — from the brain to the spinal cord — is very difficult. Imagine a massive, massive switchboard . . . people can say we can suture a spinal cord together, but that just shows you a picture of something connected — it doesn’t mean they are truly connected.”
Kenichi Okamoto, investigator at Mount Sinai Hospital’s Lunenfeld-Tanenbaum Research Institute:
“Yes, a human head transplant is possible, maybe even within this decade, but whether it is deemed successful may depend on your viewpoint. The late U.S. neurosurgeon, Dr. (Robert) White, performed a head transplant using a monkey, but it survived for only nine days. The biggest problem presents when reconnecting the nervous system, which controls movement of the body. When the monkey recovered, it could move its facial muscles and eyes, but the body was left immobile; and the state of its cognitive and psychological function remained questionable. Nonetheless, scientists are gradually finding alternate ways to re-establish spinal cord-body communication, including development of an artificial spinal cord and altering nerve regeneration by stem cells and inorganic polymers.”
Molly Shoichet, professor in regenerative medicine at U of T and senior adviser on science and engineering engagement:
“Since the brain is the control centre for our bodies, even fixing a small part of it when the wiring goes awry is extraordinarily complicated . . . In the Shoichet lab at the University of Toronto, we are particularly excited about some of the advances that we have made in models of stroke. We have been pursuing two approaches: we have been able to transplant brain stem cells and show functional repair in a model of stroke; and we have been able to deliver therapeutic proteins directly to the brain to stimulate the resident stem cells to promote tissue repair in a model of stroke. These studies demonstrate the potential of regenerative medi- cine to overcome diseases in the brain — yet also represent just the first step of many to bring these therapeutic strategies to patients.”
Kerry Bowman, U of T’s Joint Centre for Bioethics:
“Probably the biggest ethical question that comes forward immediately is that it raises very deep questions about human identity and the sense of self . . . How much of the new body can be integrated with the sense of self? It’s actually a very deep and unknown question ... The whole mind/body dichotomy we’re so caught in in western culture would really come to the forefront with this kind of situation. And the yuck factor would be huge. Right now in 2015 it’s pretty laughable — I say that with caution, because it could happen at any point.”
Christopher Forrest, medical director of The Centre for Craniofacial Care and Research at The Hospital for Sick Children:
“In most sophisticated academic or even community hospitals, there are fairly rigid rules on what’s acceptable in terms of medical behaviour and surgical adventures. Certainly within North America, to do a transplant, whether it’s a hand or a face or even a uterus, we have to go through a very, very rigorous and rigid process of ethics board approval . . . Having said that, I’m sure there are hospitals in the world that don’t have that same level of rigour and may be looking for an opportunity to be in the news and be the first place that’s done it.”