A leading neurosurgeon has revealed a project to carry out the first human head transplantation with spinal linkage within the next two years. The project is code-named HEAVEN/GEMINI.
Published in the June issue of Surgical Neurology International, the project has been outlined by Italian neuroscientist and functional neurosurgeon, Dr. Sergio Canavero. He says the procedure would take 100 surgeons 36 hours to complete, and would cost around £8.5 million ($12.6 million).
In 1970, US neurosurgeon Robert Joseph White performed an operation to transplant a monkey's head onto another monkey's body. However, the inability to repair the severed spinal cord due to lack of required technology proved a problem, and the monkey was left paralyzed, passing away days later.
But Canavero believes today's technology will overcome this hurdle and refers to previous studies in which scientist have reconnected spinal cords to rats. Canavero explains that the transplant will work if surgeons can successfully link the spinal cord to the head by fusing severed axons, the nerve cells that transmit information to different neurons, muscles and glands.
In the paper, Canavero explains:
"The greatest technical hurdle to such endeavor is of course the reconnection of the donor's and recipient's spinal cords. It is my contention that the technology only now exists for such linkage."
He explains that cut axons can be reconstituted using molecules such as poly-ethylene glycol (PEG), used in many areas ranging from industrial manufacturing to pharmaceutical products. Another molecule that can be used is chitosan.
The surgery would involve putting the recipient's head into a "hypothermia mode" for around 45 minutes between 12°C and 15°C (the HEAVEN process). It is thought that this time frame would create virtually no neurological damage.
The GEMINI procedure would involve surgeons cutting the cooled spinal cords with an "ultra-sharp blade," before reconnecting the recipient's head to the donor body. In the paper, Canavero explains that this clean cut is the key to spinal cord fusion, as it allows the severed axons to be fused accurately with the molecules.
The transplantation of a human head would be incredibly complex.
He explains that what is equally important is that the motorneuronal pools, responsible for the contraction of muscle fibers and skeletal muscle, remain fully intact so they can be engaged by spinal cord stimulation. Canavero says that this is a technique that has proven effective for motor control in patients with spinal injuries.
As the human brain can only survive without oxygen for one hour, the surgeons would have to remove both heads and connect the recipient's head to the circulatory system of the donor body within this time frame.
Canavero says that it is clear the procedure would extend some patients' lives and would be far-reaching. However, he says that a select group of gravely ill individuals would be the target, such as people with muscular dystrophies.
But he cautions that as the procedure is deployed within the clinical area, it needs proper regulation. He adds that a risk could develop whereby people with adequate funds try to secure the bodies of healthy young individuals on the black market and have them transplanted by dishonest surgeons - something he says needs to be addressed by society.