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The heart of a genetically modified pig has been successfully transplanted into a monkey, according to scientists in South Korea.
It is the first time the country has claimed to have accomplished such an inter-species operation
Known as xenotransplantation, it is seen by some as a way to end the chronic shortage of human organs available for transplants.
Before the controversial procedure, conducted in Seoul, the cloned pig had its genes responsible for immune rejection removed.
The ultimate aim of such experimentation would be to put pig hearts and other swine organs into humans.
And the South Koreans believe this could become a commercially viable reality within five years.
The first known transplant of a genetically engineered pig heart in a primate was performed in 1994.
But the possibility of animal-to-human operations has divided the medical ethics community.
Medical ethicist Associate Professor Nicholas Tonti-Filippini, speaking in 2010, said such transplants had the potential to bring animal diseases into the human population.
In 2009, Israeli scientists transplanted embryonic pancreatic tissue from pigs to monkeys to combat type 1 diabetes.
As a result, the researchers were able to reverse the primate’s insulin deficiency, MIT reported.
They said the key to their breakthrough was the embryonic tissue’s ability to grow into a new pancreas that uses blood vessels from the host animal.
The host blood vessels are not subject to the risky immune reaction that has always impeded xenotransplants of mature pancreatic material.
Yair Reisner of the Weizmann Institute, who led the research, claimed that the results, published in the journal PNAS, could offer a viable replacement therapy for sufferers of type 1 diabetes, which destroys the pancreas.
He said the creation of genetically modified pigs was not ethically acceptable, explaining: ‘It is basically a human-pig, a hybrid, or whatever you want to call it.
‘It is about whether the community is prepared to accept a part human, part animal.’
South Korean scientists first claimed to have cloned a piglet whose organs were genetically modified to make them more suitable for human transplants in 2009.
Lead scientist Lim Gio-Bin said the cloned piglet, born on April 3, had been genetically altered to lack the ‘alpha-gal’ gene which triggers tissue rejection, according to PhysOrg.
He said his government-sponsored team, involving scientists from four universities and two research institutes, used stem cells of smaller-than-normal pigs to clone ‘mini-pigs’ with modified genes.
Immuno-rejection has been a major hurdle in human organ transplants.
Pig organs are well suited for transplantation but are coated with sugar molecules that trigger acute rejection in human bodies.
Human antibodies attach themselves to such molecules and quickly destroy the transplanted pig organ.
In cloning a pig called Xeno, the scientist said his team adopted almost identical technology to that used by U.S. scientists in 2002 to create cloned piglets, in which one copy of the sugar-producing gene was ‘knocked out’.
An organism receives two copies of a gene, one from the mother and one from the father. Scientists have tried to produce pigs lacking both copies, so far unsuccessfully.
‘Through our achievement, South Korea became the second country in the world to clone such piglets after the United States,’ Lim said at the time.
Lim said then that his team would conduct clinical trials on humans in 2012 and he believed genetically modified mini-pigs could be used commercially around 2017.
Two years ago, Australian scientists kept pig lungs alive and functioning with human blood.
The breakthrough came after scientists at Melbourne’s St Vincent’s Hospital were able to remove a section of pig DNA which made the pig organs incompatible with human blood.
Prof Tony D’Apice – who had been breeding pigs for possible transplants since 1989 – said human DNA was added to the engineered animals to control blood clotting and rejection in humans.
Dr Glenn Westall, from the Alfred Hospital in Melbourne, said the world-first discovery meant pig-human lung transplants were a real prospect.
- Live Chat: The Science of Organ Transplantation (news.sciencemag.org)
- The Link Between Genetically Modified Food and Cannibalism (aspoonfulofsuga.wordpress.com)
- Introducing The Next Generation Of Genetically-Engineered Animals (businessinsider.com)
- What Are You Feeding Your Family? GMOs Upclose (revolutioninmedia.com)
- Heart of genetically modified pig ‘successfully transplanted into monkey’, South Korea scientists claim (junkscience.com)