Bethesda - Genetically-modified pig hearts could eventually be transplanted into human patients after a porcine organ beat for nearly three years after being implanted into a baboon.
The success of the experiment has raised hopes that pig hearts could soon be used to combat the dire shortage of organs from human donors, which mean patients often die before they receive a transplant.
The scientists used a technique known as immunomodulation to overcome natural rejection that occurs when tissue from another species is implanted into a human body.
The immune system typically attacks organs that it does not recognise but scientists at the National Heart, Lung and Blood Institute in Maryland used genetically-modified pigs hearts to make them more tolerable for baboons. They were implanted into five baboons together with a combination of antibodies and drugs which changed their immune systems, so they would not attack the organs.
Losing a loved one really can break your heart, although not for ever, research suggests.
People who lose a partner are at an increased risk of developing an irregular heartbeat for the next 12 months, Danish scientists have found in a study published in the BMJ's Open Heart journal.
The risk seemed to be greatest eight to 14 days following a death, after which it gradually subsided until, after a year, the risk was similar to that of someone not bereaved.
It affected worst those under 60 when the loss of the partner was least expected.
As a result, the hearts survived for as long as 945 days - smashing the previous record of 500 days, held by the same researchers.
“This is very significant because it brings us one step closer to using these organs in humans,” said Muhammad Mohiuddin, co-author of the report.
“Xenotransplants - organ transplants between different species - could potentially save thousands of lives each year that are lost due to a shortage of human organs,” he said.
In the experiments, the hearts did not replace those of the monkeys but were rather connected to the circulatory system via two large blood vessels in the baboons' abdomen.
The transplanted heart beat like a normal heart but the baboon's own heart continued the function of pumping blood.
Scientists have been experimenting with transplanting primate kidneys, hearts and livers into humans since the 1960s because their genetic proximity to humans suggested they would make the best donors.
But pigs have emerged as a better option because while their hearts are anatomically similar to ours they pose less of a risk of disease transmission than primates - which are so genetically close to humans they pose a much higher danger of spreading disease.
Pigs are also numerous and they grow up fast, while primates such as chimpanzees are endangered and take a long time to grow.
The research has been published in the journal Nature Communications .
The Independent