Head transplant

A head transplant is a surgical operation involving the replacement of an organism's head with a replacement head. It should not be confused with another hypothetical surgical operation, the brain transplant. Head transplantation invariably involves decapitating the patient.

Since the technology required to reattach a severed spinal cord has not yet been developed, the subject of a head transplant would be a quadriplegic, unless proper therapies, presumably along the lines of stem cell therapy, had been developed. This technique has been proposed as possibly useful for people who are already quadriplegics, and who are suffering from widespread organ failures which would otherwise require many different and difficult transplant surgeries. It may also be useful for people who would rather be quadriplegic than dead (for example because of progress in brain-computer interfaces). As of this time, there is no uniform consensus on the ethics of such a procedure.

History
As the book, Stiff: The Curious Lives of Human Cadavers explains:

On May 21, [1908, Charles] Guthrie succeeded in grafting one dog’s head onto the side of another’s neck, creating the world’s first man-made human two headed dog. The arteries were grafted together such that the blood of the intact dog flowed through the head of the decapitated dog and then back into the intact dog’s neck, where it proceeded to the brain and back into circulation. Guthrie’s book Blood Vessel Surgery and Its Applications includes a photograph of the historic creature. Were it not for the caption, the photo would seem to be of some rare form of marsupial dog, with a large baby’s head protruding from a pouch in its mother’s fur. The transplanted head was sewn on at the base of the neck, upside down, so that the two dogs are chin to chin, giving an impression of intimacy, despite what must have been at the very least a strained coexistence....too much time (twenty minutes) had elapsed between the beheading and the moment the circulation was resorted for the dog head and brain to regain much function. Guthrie recorded a series of primitive movements and basic reflexes, similar to what Laborde and Hayem had observed: pupil contractions, nostril twitchings, “boiling movements” of the tongue.

The first dog heads to enjoy, if that word can be used, full cerebral function were those transplantation whiz Vladimir Demikhov, in the Soviet Union in the 1950s. Demikhov minimized the time that the severed donor head was without oxygen by using “blood-vessel sewing machines.” He transplanted twenty puppy heads—actually, head-shoulders-lungs—and forelimbs units with an esophagus that emptied, untidily, onto the outside of the dog—onto fully grown dogs, to see that they’d do and how long they’d last (usually from two to six days, but in one case as long as twenty-nine days).

In his book Experimental Transplantation of Vital Organs, Demikhov included photographs of, and lab notes from, Experiment No. 2, on February 24 1954: the transplantation of a one-month-old puppy’s head and forelimbs to the neck of what appears to be a Siberian husky. The notes portray a lively, puppy like, if not altogether joyous existence on the part of the head:

09:00 The donor’s head eagerly drank water or milk, and tugged as if trying to separate itself from the recipient’s body.

22:30 When the recipient was put to bed, the transplanted head bit the finger of a member of the staff until it bled.

February 26, 18:00. The donor’s head bit the recipient behind the ear, so that the latter yelped and shook its head.

Demikhov’s transplant subjects were typically done in by immune reactions.

In 1959 China announced they had succeeded in transplanting the head of one dog to the body of another twice.

In 1963 a group of scientists from Case Western Reserve University School of Medicine in Cleveland Ohio, led by Robert J. White, a neurosurgeon and a professor of neurological surgery who was inspired by the work of Vladimir Demikhov, performed a highly controversial operation to transplant the head of one monkey onto another’s body. The procedure was a success to some extent, with the animal being able to smell, taste, hear, and see the world around it. The operation involved cauterizing arteries and veins carefully while the head was being severed to prevent hypovolemia. Because the nerves were left entirely intact, connecting the brain to a blood supply kept it chemically alive. The animal survived for some time after the operation, even at times attempting to bite some of the staff. In 2001 the operation was successfully repeated on a monkey by Dr. White again.

Other head transplants were also conducted recently in Japan in rats. Unlike the head transplants performed by Dr. White, however, these head transplants involved grafting one rat's head onto the body of another rat that kept its head. Thus the rat ended up with two heads. The scientists said the key to successful head transplants was to use low temperatures.

A human head transplant would most likely require cooling of the brain to the point where all neural activity stops. This is to prevent neurons from dying while the brain is being transplanted. Ethical considerations have thus far prevented any reported attempt by surgeons to transplant a human being's head.

Future and stem cells
Through medical science it is now known that stem cells are capable of specializing into any type of cell found in the human body. In 1998 Fred H. Gage of the Salk Institute in La Jolla, California, showed the new, functioning neurons are indeed capable of being grown in the human hippocampus. Historically this was thought to be preposterous. The news gives a ray of hope for individuals suffering disabling diseases. Most believe the key to helping individuals whose bodies are incapable of sustaining them is not through arguably crude operations like a head transplant, but through stem cell research. However, the tenet of head transplantation may become more popular, as stem cells have been shown by the Wistar Institute of the University of Pennsylvania to repair the severed spinal cords of mice to a functional level. This could mean the subject would no longer be condemned to quadriplegia.

Should the technology to repair the damage to the spinal cord be developed, the possibilities of what a head transplant could accomplish will become endless. A disease such as cancer (non-brain) which afflicts an area of the body such as the lung or bladder, as well as other diseases such as diabetes which affects the pancreas and heart disease could be cured through the transplantation of the head. These diseases all affect the body but not the head. Should the head be transplanted these afflictions would be left behind in the old body while the new body enabled the head transplant recipient to live a longer healthier life. This would ultimately serve to improve the standard of living for the recipients, and could potentially double their life spans.

In 1998 Charles Krauthammer of Time magazine warned of the potential medical future of head transplanting with cloning:

At the University of Texas and at the University of Bath. During the past four years, one group created headless mice; the other, headless tadpoles. Why then create them?...Take the mouse-frog technology, apply it to humans, combine it with cloning, and you are become a god: with a single cell taken from, say, your finger, you produce a headless replica of yourself, a mutant twin, arguably lifeless, that becomes your own personal, precisely tissue-matched organ farm...Congress should ban human cloning now. Totally. And regarding one particular form, it should be draconian: the deliberate creation of headless humans must be made a crime, indeed a capital crime.