Head transplant also known as full body transplants involve the transfer of the whole head to a new body. They are not just an idea seen in science fiction movies. The first head transplant was performed back in the 1950`s by the surgeon and transplant pioneer Vladimir Demikhov.
He grafted the forelimbs and head of a puppy into the body of a different puppy. Demikhov followed this with more famous head transplants that involved the creation to two headed dogs. However, the animals all died after a few days.
The head transplant procedures performed by Demikhov are ethically questionable, but they led to the first successful head transplant that Dr. Robert White performed on a monkey in 1970. White demonstrated that the procedure was feasible, but he did not try to fuse the spinal cord or the donor monkey with the recipient. The recipient was paralyzed and could only breathe with assistance.
Even though not much has been done since his procedure, medicine has advanced so much that one neurosurgeon believes that a head transplant could be performed on humans soon.
According to Italian neurosurgeon Dr. Sergio Canavero, the major obstacles to performing this procedure can be overcome due to advancements in medicine. He says that with further advances, the procedure could start being carried out in the year 2017.
Dr. Canavero is not the only doctor who is looking forward to performing a head or full body transplant. Dr. Xiaoping Ren, who is a Chinese orthopedic surgeon, told the New York Times that he was building a team to carry out the procedure. He works at the Harbin Medical University.
The New York Times reports that Dr. Xiaoping Ren already has plans to carry out the procedures. About twenty years ago, Ren was a member of a team from the University of Louisville that performed the first-hand transplant in the United States. He spent sixteen years in the United States before returning home to Harbin, China.
Dr. Rep has made headlines for carrying out thousands of head transplants on mice. However, the animals lived for only twenty-four hours. Several scientists have explored the idea of performing full body transplants to save people who are suffering from deadly ailments like spinal muscular atrophy and cancer as well as those who have sustained serious injuries in an accident.
They can also perform the procedure in order to extend life. However, this can only happen if scientists come up with ways to deal with the many obstacles of carrying out this procedure. They include the following:
In all transplants, the organ that is taken from the body of a donor has to be kept alive until the time when it will be placed into the recipient’s body. Organs begin to die once they are removed from a body. When performing kidney, liver and heart transplant procedures, surgeons cool the organs to keep them viable. Cooling the organs reduces the amount of energy cells they need to remain alive.
Physicians accomplish this by bathing the organs in a solution of saline water. Through this process, it is possible to preserve the kidneys for forty-eight hours, hearts for five to ten hours and livers for twenty-four hours. However, the process of preserving a head is more difficult because it is one of the most complicated parts of the body. It houses the brain, eyes, mouth, nose and ears.
The head also houses two pituitary gland systems, namely the pituitary gland and the salivary glands. The pituitary gland controls the hormones, which circulate throughout the body while the salivary glands produce saliva. For more than a hundred years, scientists have studied the effect of decapitation in the heads of animals. They have concluded that blood pressure in the head drops significantly after decapitation. The loss of oxygen and fresh blood pushes the brain into a comma, which is soon followed by death.
After performing any transplant, one of the main problems that doctors have to deal with is the fact that the immune system rejects the recently introduced organ. The immune system of the recipient detects substances on the cells of the new organ.
These substances are known as antigens and they trigger the immune system. To prevent rejection, all patients who receive an organ have to take immune suppressing drugs. Since the head has many organs, the risk of rejection is high.
When Robert White performed a head transplant procedure on a monkey, he maintained the bodies of the animals by cooling them to about 15 degree Celsius (59 degrees Fahrenheit) for the entire duration of the procedure. The recipient of the head survived until its immune system rejected it 8 days after the surgery.
According to Dr White’s and Canavero’s paper, the procedure had to be completed in less than 60 minutes. In the paper, Canavero notes that both heads must be removed from their bodies simultaneously. The surgeons then have to work swiftly to reattach the head to the body of the individual they want to keep alive to the circulatory system, of the body of the donor. Both bodies will be under cardiac arrest.
The head that is transplanted on the recipient’s body must be able to communicate with and control the new body. For this to happen, the brain and the spinal cord must be seamlessly fused or connected. This did not happen when the procedure was carried out on the monkey. The monkey that received the head was able to eat, move its eyes and see, but it was paralyzed from the neck down.
The biggest hurdle to a successful head transplantation procedure is the reconnection of the donors and recipient’s spinal cords. Nerve tissue may also not heal properly. It is also very difficult for nerve tissue to transmit signals. However, Dr. Canavero says that the linkage of both spinal cords can happen due to recent technological advancements. He says that a special biological glue known as polyethylene glycol can be used to fuse the spinal cords.
This material was used in the 1930s and 1940s by surgeons to fuse the spinal cords of dogs. However, the experiments usually involved attaching another head to the complete body of a dog, to give it two heads. The surgeons also completed these procedures in less than sixty minutes.
Once the head transplant procedure is over, Canavero says that the patient would be placed in a medically induced coma for up to one month to allow the spinal cords to fuse properly. However, a month long coma is a potential problem because medically induced coma can result in blood clots, infection and minimal brain activity.
Prior to performing head transplantation in humans, surgeons have to address these obstacles in animal trials. It is not easy to get animal experiments approved because they involve a lot of cruelty. In order for such a procedure to be approved, the doctors who want to perform it must prove that it is necessary and helpful. There is no evidence that this will happen soon. Therefore, full body transplants may not be performed for several decades to come.