The first known xenotransplantation was done by the God Shiva. Daksha, the father in law of Shiva, organised a yagna where he insulted Shiva and his daughter. Sati, Shiva’s wife, immolated herself in protest. Daksha’s head was cut off and burnt. Later, when Shiva forgave him, he was brought back to life but with a ram’s head. The more famous decapitation was that of Ganesha. Shiva cut off the head of a baby elephant and transplanted it on to his son’s neck.
For the last 300 years, doctors have been trying to replicate this miracle. The process is called xenotransplantation, or the transplanting of non-human organs or cells into a human body.
Thousands of animals have died in the process. And each attempt has been a failure. But that doesn’t stop scientists from trying. After all, animal life is cheap and, in the name of science, one can do anything.
In the 17th century, Jean Baptiste Denis started the practice of blood transfusion from animals to humans. Everyone died and xenotransfusion was banned in France for a number of years. In the 19th century, skin grafts became relatively popular between various animal species and humans. The fact that many of the species used as donors—sheep, rabbits, dogs, cats, rats, chickens, and pigeons—had hair, feathers, or fur, growing from the skin, did not deter the surgeons involved. The ideal graft was from frogs, which were sometimes skinned alive. None of the grafts was successful.
In the 20th century, the French experimental surgeon, Alexis Carrel, developed surgical techniques for joining blood vessels, which enabled organ transplantation to be carried out successfully for the first time. For this work, he was awarded the Nobel Prize in 1912. He developed an interest in cross-species transplantation and his techniques became a reason for more people to experiment on animals.
A few years later, Serge Voronoff, a Russian émigré working in Paris, developed an interest in reversing the effects of ageing in elderly men who had lost their “zest for life.” He sliced a large number of chimpanzee or baboon testicles and implanted them in the testicles of old men. None of them had any effect. In fact, they created infections and more complications. The concept of transplanting glandular tissue to produce hormones that would benefit the recipient was continued in the United States by John Brinkley, whose the chosen donor was the goat, as he had been convinced by a local farmer of its sexual potency. He was later disbarred by the American Medical Association.
In the 1960s, Keith Reemtsma at Tulane University in Louisiana—hypothesised that nonhuman primate kidneys might function in human recipients and thus be a successful treatment for renal failure. By then kidney transplantation from human to human had been established (in the 50s), but the availability of kidneys from deceased humans was extremely limited. Reemtsma selected the chimpanzee as the source of organs, because of its close evolutionary relationship to humans. He carried out 13 of these transplants. While all the chimpanzees died in great pain the experiments failed. One woman lasted nine months but spent all that time strapped to a bed and hospital catheters. In another experiment scientists transplanted a pig kidney into a baboon. The baboon died in 5 months.
But the scientists carried on with kidney transplants. Tom Starzl used baboons as donors in Colorado. His results were similar to those of Reemtsma.
James Hardy, in 1964, tried to transplant a chimpanzee heart into a patient who had undergone amputations of both legs—and was in a semi-comatose state at the time the transplant was undertaken. The patient died within a few hours. The chimpanzee, of course, had been killed. In 1967 Christian Bernard also carried out two cardiac xenotransplants. Both failed.
Perhaps the best known clinical cardiac xenotransplantation since Hardy's attempt was that by Leonard Bailey, who transplanted a baboon heart into an infant girl, known as Baby Fae, in 1983. The graft underwent acute rejection and the patient died 20 days later. One of the reasons, which would appear common sense to an average, non medical person, is that baboons don’t have O blood type, which is donor blood. They have ABO which is incompatible with humans.
Tom Starzl, who is considered one of the pioneers in the field of kidney and liver human to human transplantation, performed a handful of liver transplants between nonhuman primates and young patients in Colorado in the 1960s, with no success. As more immuno-suppressants became available, he performed two liver transplants from baboons into adult patients in the 1990s, with no survivors.
In the meantime xenotransplantation of pig islet transplantation is underway in diabetic patients in New Zealand. A European group has given rhesus monkeys an artificially induced Parkinson like motor disease and is experimenting with genetically modified pig dopamine-producing cells from pig embryos into the monkey brain, so that this can eventually be done with people with Parkinson’s. No luck so far, but there is no shortage of monkeys being imported from Mauritius.
The people of Asia and Africa need new corneas. Experimental corneal xenotransplantation is being done. Transplanting pig corneas into monkey eyes. The recipient needs corticosteroid injections into the eyes for the rest of his life – if the four experiments work which they have not done so far. Nebraska Medical Center is transplanting hearts from pigs into sheep. Pig xenotransplants of heart, kidneys, lungs and livers, into apes carries on. The results? Completely unsuccessful. Does that stop the scientists? Not yet.
Clinics in Europe tout the efficacy of various animal tissues from placentas to blood cells, plasma and organs for a variety of conditions – from acne to anti-aging. There is no evidence that they work.
The pig is now the creature that is being focused on. Why? Its genetic makeup is completely different from that of a human being. But the reasons are far more commercial. Its organs are the same size as humans, it is cheap to maintain and it has three litters a year, so pigs can be easily available. Does this make any scientific sense? No. But by the time they give up, xenotransplantation companies will have tortured and killed millions of pigs.
In 1969, Nobel Prize winner Sir Peter Medawar, who is considered the father of transplant immunology, stated, “We should solve the problem of organ transplantation by using xenografts in less than 15 years.” It is now 2017 and we are no closer. Norman Shumway, the pioneer of heart transplantation, stated truthfully “xenotransplantation is the future of transplantation, and always will be.”
The scientists are going to keep trying. They get paid for their research and, if they do succeed in producing usable organs from pigs, then there is a Nobel Prize at the end of the rainbow. Who cares about the animals.
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Updated Date: Jan 02, 2018 16:10:54 IST