Thinking Ahead12 May 2015
The following article includes descriptions of medical procedures and animal studies.
In the year 2017, neuroscientist Dr Sergio Canavero plans to perform the world’s first head transplant. Valery Spiridonov, a man with muscle atrophy, has volunteered to be the patient whose head is transplanted onto a brain-dead donor body. It sounds like something out of science fiction, and incredibly, Dr Canavero claims that we could use his method along with cloning to achieve immortality within decades. He imagines a world where we keep clones of ourselves as back-ups, ready to transfer our heads onto when our bodies grow too old. This is despite the fact that we have never cloned a human.
With astounding claims like these, it is no wonder that Dr Canavero’s announcement has been met with disbelief. Nothing like this has ever been attempted on a human before, and the animal studies that have been performed have not been very successful. These experiments include the creation of a two-headed dog, and transplanting the head of a macaque monkey onto another monkey’s body. All of the animals died after a few days. Dr Robert White, scientist who performed the monkey head transplant in 1970 was widely criticised for his work, earning the moniker “Dr Butcher”. One protest even interrupted a dinner held in Dr White’s honour, where he was presented with a replica of a blood-covered human head.
Despite all this, Dr Canavero is confident he will be able to perform the procedure that he has named HEAVEN, an acronym of head anastomosis (the surgical connection of two structures) venture by 2017. He has stated that by using a very sharp scalpel to cleanly cut both the spinal cords, there will be a better chance of reconnection. He will then use a drug to glue the two spinal cords together. The bodies will be kept at very low temperatures, and then Spiridonov will be put into a coma for around a month. However, our current understanding of the brain and these surgical techniques suggests that Dr Canavero’s method will not work.
You can’t just glue people back together
Dr Canavero plans to use a drug named polyethylene glycol (PEG) to fuse the two severed spinal cords together. PEG allows lipid bilayers (the fatty membranes of our cells) to mesh together, and has been shown to repair spinal cord injury in guinea pigs when administered shortly after injury. However, the effectiveness of this treatment in humans is not yet known. The cells in our brain and spinal cord are resistant to change, and some damage in the central nervous system can never be repaired. Dr Kitchener, a member of staff from the University of Melbourne’s neuroscience department, has stated that “there is nothing – not even the ‘miracle of PEG’ – to suggest that a brain to spinal cord reconnection can be made.”
The brain needs constant energy
Neurons (the cells of our brains) are fragile cells with high energy demands, and are totally dependent on a constant flow of energy. The loss of oxygen or glucose to the brain for only a few minutes is fatal. Dr Canavero plans to cool Spiridonov’s brain to extend the time he has to perform the surgery. Although this will help, his time will still be very limited, and it is doubtful that he will have enough time to connect all the structures he needs to without damaging Spiridonov’s brain.
Our brains are fine-tuned for our bodies
Every day, our brains are changing. Our experiences and thoughts can change how our brains are wired, leading to new connections. With over 86 billion neurons in the brain, the connections these neurons make are in the trillions. It is claimed that the human brain is the most complex system we know of in the entire universe. Dr Canavero is relying on the fact that Spiridonov’s brain will adapt to his new body. But our brains are unique, and we do not know what could happen to him if the transplant is successful.
For these reasons and numerous others, there is not enough evidence to suggest a head transplant is possible within the timeframe that Dr Canavero has claimed. If Dr Canavero does succeed, it is widely believed that the outcome will not be good for the patient. I do not believe that this surgery is currently possible, or that Dr Canavero should even attempt it considering the danger to his patient. However, this has opened up many new avenues of discussion, as experts from around the world join together to discuss the issues and implications of the proposed surgery. I hope that this event will allow us to discover more about the nervous system, and new ways to help treat people like Valery Spiridonov.
The author gratefully acknowledges Amanda Copp and Dr Peter Kitchener for their insight and expertise, and wishes to state that any errors in this article are her own.