Will the head transplant extend human life expectancy?

Neurosurgeon: "Human heads can be transplanted in just two years"

Turin / Vienna - Since Christiaan Barnard and Hamilton Naki first transplanted a human heart on December 3, 1967 in Cape Town, a lot has happened in the field of organ transplantation. In the meantime, there seems to be only one final limit - and it seems that a surgeon will soon want to cross this too: The Italian neuroscientist Sergio Canavero of the Turin Advanced Neuromodulation Group thinks that it is now time to make human Transplant heads. He is convinced that the medical problems associated with such an undertaking should be resolved within two years at the latest. Other scientists, however, are much more skeptical.

Canavero and his employees first presented such plans in 2013. The project called Head Anastomosis Venture with Cord Fusion, in short: HEAVEN, according to the scientist, is primarily intended to help people who suffer from degenerative diseases of the muscles and nerves or cancer. The money for this is to be collected in part via crowdfunding.

Apart from the ethical questions, the greatest challenges with such an intervention are to create a functioning connection between the two ends of the spinal cord and to keep the body's immune system from rejecting the head again. Canavero has now announced that both hurdles could be overcome by 2017. The researcher wants the concrete plans from Annual conference to the American Academy of Neurological and Orthopedic Surgeons (AANOS) in Annapolis, Maryland, next June.

First animal experiments

The Soviet surgeon Vladimir Demichow carried out the first animal experiments, which - if you will - were somewhat successful on dogs in 1954. The transplant pioneer transplanted the head and front legs of a puppy onto the back of an adult German Shepherd. The unfortunate creatures, however, only survived a few days. Similar tests were carried out in the USA. For example, Robert White of the Case Western Reserve University School of Medicine in Cleveland, Ohio, connected the head of one monkey to the body of another. The animal suffered severe paraplegia because the spinal cord remained interrupted. Nevertheless, the monkey survived fully conscious for nine days before an immune reaction finally rejected the foreign tissue.

Transplant medicine has made significant advances since then, so Canavero believes that nothing stands in the way of a successful head transplant. In particular, immunosuppressive therapies are now at a level that would allow such an intervention, he says. In a paper that has now been published in the journal "Surgical Neurology International", the researcher presents how this could be achieved in concrete terms.

Clean cut

First, the body temperatures of the head and donor body would have to be reduced significantly in order to extend the life of the tissue without oxygen supply. In the next step, the larger blood vessels are cut; those of the head would then have to be connected to the vessels of the body by means of thin tubes. Finally, the respective spinal cord is severed. According to Canavero, a clean cut is of crucial importance.

For the connection of the spinal cord fibers, the researchers rely on polyethylene glycol, which is mainly used today in the cosmetics industry. The substance is said to significantly increase the chance that the nerve endings will form a functional connection. Experiments by German researchers with rats and mice proved in the previous year that the method works at least partially. Finally, the muscles and blood vessels are put back together. To prevent movement during the healing process, the patient should remain in a coma for three to four weeks while implanted electrodes stimulate the spinal cord. The researchers believe that this could additionally strengthen the nerve connections.

Canavero and his team are convinced that the patient will be able to start moving shortly after waking up. Physiotherapy should ultimately lead to the patient being able to walk again within a year. However, professional colleagues are more than skeptical that this will be possible in the foreseeable future.

Medical colleagues more than skeptical

Richard Borgens, director of the Paralysis Research Center at Purdue University in West Lafayette, Indiana, rejects the idea of ​​a successful head transplant in the near future. "There is no evidence that a connection between the spinal cord and the brain leads to meaningful sensory or motor functions after a head transplant," he explains in "New Scientist". Other medical professionals did not even want to comment on the subject. The very idea is "too otherworldly" to judge seriously and seriously.

There should be no shortage of interested parties. According to Canavero, numerous volunteers have already signed up who are keen on a new body. Whether it actually comes to that, however, does not depend solely on medical feasibility. The ethical aspect of such an endeavor could cause problems for the Italian neurosurgeon to find a country that would ultimately give permission for a head transplant. (tberg, derStandard.at, 1.3.2015)