Last week, pioneering transplant surgeon Sir Terence English, who had performed the first heart transplant in the United Kingdom in 1979, declared that his team would this year transplant a pig’s kidney into a human’s body. And in three years, he claimed, a heart transplant can be achieved.
The statements reopened an old controversy around xenotransplantation, or the transplanting of organs from one species to another. There is a precedent from years ago — 1997 — with an attempted pig-to-human heart transplant in India.
The doctor in Assam was held guilty of an unethical procedure, and imprisoned for 40 days. Yet, many see hope in the potential of xenotransplantation to save lives.
The first attempts at animal-to-human transplants were made in 1838, when the cornea of a pig was transplanted into a human. Between 1902 and 1923, organs from pigs, goats, sheep, and monkeys were used in unsuccessful transplantation attempts. From 1963 onward, researchers attempted organ transplantation from chimpanzees, baboons and pigs. In 1984, a two-week-old baby in the United States received a baboon’s heart, but died within three weeks.
For fear of transmission of viruses from animals to humans, xenotransplantation has for long been an area that governments and doctors have treated with caution. Researchers are now trying to genetically alter pigs to enable organ transplantation in humans.
Need to look at animal organs
The need for organ donation is rising globally alongside the rise in kidney, liver and heart ailments. “Several die while waiting for an organ donation,” said Dr Astrid Lobo Gajiwala, director of Regional Organ and Tissue Transplant Organisation, Western India.
India’s national registry shows 1,945 liver and 7,936 kidney transplants were conducted in 2018. This is when India needs 1.8-2 lakh kidney transplants every year, as per the Ministry of Health and Family Welfare data. With a lack of human cadavers as donors, researchers are looking at animal organs as an alternative.
“In India, this is a distant dream, since animal rights laws do not allow us to even experiment,” said heart transplant surgeon Dr Anvay Mulay.
Why pigs in particular?
A pig’s genetic make-up and internal organs are similar to a human’s. Its weight, the tendency to become obese, lipids, arterial pressure, heart rate, renal function, electrolyte balance, and digestive system match those in the human body.
The problem is that the rejection rate is higher in a pig-to-human transplant than in a human-to-human transplant. ‘Rejection’ is what happens when the human body’s immune system starts working against any foreign organ. In a human-to-human transplant, immunosuppressants help trick the body into accepting the foreign organ as its own. But immunosuppressants have failed to work in animal-to-human transplants.
Kidney transplant expert Dr Prashant Rajput said there are certain enzymes, proteins and amino acids in pigs that are different from those in humans. “These are substances against which the human body will produce antibodies and reject the organ. It is called antigenicity. The lower the antigenicity, the better,” Dr Rajput said.
The 1997 attempt in Assam
In 1997, heart surgeon Dr Dhani Ram Baruah, along with Hong Kong surgeon Dr Jonathan Ho Kei-Shing, conducted a pig-to-human heart and lung transplant in Baruah’s clinic in Sonapur on the outskirts of Guwahati. It was a first in India.
In an email, Baruah told The Indian Express that he “developed new anti-hyperacute rejection biochemical solution to treat donor’s heart and lung and blind its immune system to avoid rejection”.
After 102 experimental studies in Baruah’s institute, the transplant was conducted on 32-year-old farmer Purno Saikia on January 1. Saikia died a week later; the autopsy showed an infection. The transplant caused an international flutter. Baruah and Kei-Shing were arrested within a fortnight for culpable homicide and under the Transplantation of Human Organs Act, 1994, and imprisoned for 40 days. The Assam government instituted an inquiry and found the procedure unethical.
Recent research, procedures
Researchers have been trying to replace pig’s kidney proteins with human proteins, so that the human body does not reject the organ. In the University of São Paulo’s Biosciences Institute, experiments are on to genetically modify pigs. In February this year, geneticist Mayana Zatz said at a symposium that there are three genes in pigs that provoke rejection when transplanted into a human body; genetic modification of these could solve the problem.
In the United States, pigs’ hearts were transplanted in baboons, which survived for two years with the pig hearts beating alongside their own. In Massachusetts General Hospital, gene modification techniques are being used in pigs before transplanting their organs in monkeys, in the hope that these techniques can be tried in humans later. Countries such as Germany, the United Kingdom, New Zealand, Russia, Ukraine, and Mexico are conducting similar research.
Indian Council of Medical Research guidelines allows only animal-to-animal transplants. Kochi-based hand transplant surgeon Dr Subramania Iyer said the scope of xenotransplantation will be discussed in the Congress of the Asian Society of Transplantation Conference in New Delhi next month.
What can be expected now
Sir Terence English made his comments on the 40th anniversary of the UK’s first heart transplant. The Sunday Telegraph quoted him as saying that his protege during the 1979 operation is preparing to perform the world’s first pig-to-human kidney transplant before the end of this year.
“If it works with a kidney, it will work with a heart. That will transform the issue,” Sir Terence, 87, told the newspaper. Back in Assam, Baruah, a fellow of Royal College of Surgeons and Physicians, maintains that he had achieved a breakthrough, and that it was suppressed by the international fraternity.
Asked about the UK’s renewed attempts, he said, “This news published recently is same old wine filled in a new bottle. I said all this 24 years ago.”