Human-pig chimeras and the history of transplanting from animals
Researchers in California have created human-pig chimeric embryos as part of a project to grow human organs for transplantation; while it may make many people uncomfortable, we have been trying to use pigs for parts for nearly 200 years.
Being held prisoner by the Bedouin might not seem like a great place to do research, but for Irish surgeon Dr Bigger it was an experience full of opportunities. In 1835 he managed to transplant a cornea into a blind pet gazelle from a wounded wild deer; the transplantation seemed to be a success, and it inspired him to seek out similar operations, to see if they could promise a cure for blindness in humans. He tried transplantation experiments on many rabbits, and came across one instance where a wolf’s cornea had been successfully implanted into a pet pointer dog (which promptly ran away and lived wild in the woods for three months). Writing up these experiments and observations in 1838, Bigger suggested that a pig’s cornea would be the best possible match for a human being.
Seeing through the eyes of a pig?
Barely a few months later someone took Bigger up on this suggestion; Dr Richard Kissam of New York transplanted the cornea of a 6-month old pig into a young man, who temporarily regained his sight. Although corneal transplants always seemed to be a temporary fix, at best, there were some claims of better results: an 1875 promotional leaflet for the Glasgow Ophthalmic Institution claimed that Dr Wolfe, its founder had treated a man whose eye had been “totally destroyed” in an accident with molten iron. By “cutting from a live rabbit the corresponding portion of the eye which the man had lost” Wolfe had apparently returned “fair sight” to a “wonderfully grateful” patient (it’s worth pointing out that when this was reported in the Lancet the editors were clearly very sceptical about the claims).
Some doctors were even more ambitious; by 1885 five attempts had been made to transplant a whole eye from an animal into a human face. Four of those attempts used dog eyes, but the only initially successful one, by Dr HW Bradford of Boston, used a rabbit’s eye.
Black and white illustration; a man with his sleeve rolled up sits in a chair to the right, to the left a table with a lamb on top - a tube connects the lamb to the man. Another man in a fine jacket and large wig looks on.
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An early blood transfusion from lamb to man, taken from a book published in 1705. Photograph: Wellcome Library, London/Wellcome Images
Blood and Sex.
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Liquid animal products were even more widely used. The transfusion of animal blood into humans started at least as early as the 17th century – and demonstrations in the 1660s at the Royal Society in London, and in France resulted in deep disquiet, open mockery, and possibly a murder. Both the French government and the Royal Society banned human-animal blood transfusion in response.
Other bodily substances were also controversial; when, in 1889 Charles-Édouard Brown-Séquard reported his results on the use of extract of guinea pig and dog testicles to restore his lost virility, the response was in part a mixture of disbelief and disgust. Insulin, extracted at first from dogs (and later pigs and cows) was less controversial; and before the hormones oestrogen and progesterone could be cost-effectively synthesised, drugs were made from extracts of ovaries from slaughterhouses, or the urine of pregnant mares. Most infamously, in the 1920s and ‘30s the Russian surgeon Serge Voronoff promoted the transplantation of primate testicular materials (and thyroids) into adult men to treat a range of ageing and other disorders. His attempts to do the same with primate ovaries and women - and then to inseminate monkeys with human sperm - were even more controversial, and less successful.
A coloured cartoon; a variety of animals sit in the a tiered dissection theatre, watching four rabbits and a mouse or rat in lab coats - they are apparently about to dissect a frightened looking naked man with a long white beard.
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Colour lithograph: “human vivisection”, published in Lustige Blatter. Berlin, c. 1910. The rabbit says “Now no phoney sentimentality! The principle of free research requires that I vivisect this human for the health of the entire animal world”. Illustration: Wellcome Library, London/Wellcome Images
Making Human Animals
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Of course the major difference between these historical examples and the new stem cell research is that the historical practices are about putting animal products in human beings, not about putting human products in animals (with the exception of Voronoff, monkeys, and human sperm).
Safe transplantation of whole organs required innovations in microsurgery and an understanding of the immune reaction; the corneal transplants described here were undertaken without anaesthesia, the eye transplants without antibiotics, so they were difficult and dangerous interventions. The scarcity of human body products was enough to prevent much experimentation, leaving aside any social or religious taboos that might have discouraged the transfer of human materials into animal bodies.
Making animals more human was discussed in fiction, however. HG Wells’ 1896 novel The Island of Dr Moreau is often used as a morality tale against genetic engineering, but in the book the transformation of the animals into man-like hybrids is more physical. Moreau is a vivisector, he grafts skin, cuts and manipulates flesh, sets bone. For the rest, he relies on what we’d probably call neuroplasticity
the possibility of vivisection does not stop at a mere physical metamorphosis. A pig may be educated. The mental structure is even less determinate than the bodily. In our growing science of hypnotism we find the promise of a possibility of superseding old inherent instincts by new suggestions, grafting upon or replacing the inherited fixed ideas
Dr Moreau is also an exploration of the dark side of vivisection, and was published at a time when the first really successful and vocal anti-vivisection and anti-animal-cruelty groups were beginning to have an impact on policy, particularly the governance of science.
We’ve been using animals for spare parts and as medicine for centuries. If we’re uncomfortable about the idea of growing spare organs in pigs it can’t just be because this crosses a species barrier – perhaps, instead, it’s because human-pig hybrids are a rather uncomfortable reminder of how closely related we are to the animals we use.
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