Pig-to-human transplants 'one step closer'

Illustration by James Bareham  The Verge
Illustration by James Bareham The Verge

13 Agosto, 2017

The company claims that a single animal can save up to eight lives through the transplantation of different organs.

An average of 22 people die in America every day while waiting for organ transplants, but a group of researchers from the biotech company eGenesis hope to eventually change that statistic by using organs from cloned pig cells.

In fact, a team of scientists from the University of Alabama at Birmingham recently engineered pig organs that are free of carbohydrates, which typically make the organs targets for rejection. Recent gene editing advances, however, are rejuvenating interest in pig-to-human transplants.

In an effort to overcome the stumbling blocks preventing animal-to-human transplants - something that would ease the pressure on organ transplant waiting lists - scientists looked into modifying a pig's genome to remove harmful retroviruses. For decades, scientists have thought animals could solve the problem.

George Church, professor of genetics at Harvard Medical School, revealed that genetically modified pig organs could be used in transplants to human - as the NHS battles to find suitable donors.

"We got perfectly healthy piglets", Church tells The Verge, "so that's unbelievable".

Yang said that such genome damage is not a problem for the team, as they can select undamaged cells to use for the creation of embryos. And regulators require stringent tests in lab primates before a single patient could get a CRISPR'd pig organ; that will take years.

Pigs have always been seen as a viable source for organ transplants to humans because their organs are similar in size. But doctors have used some pig parts - like heart valves or pancreas cells - as replacements in humans before and there was no evidence of infection in those cases.

The new research combines two great achievements in recent years - gene editing and cloning. Porcine retroviruses (PERVs) are now one of the big safety barriers preventing us using pigs as organ donors. This experimental biomedical technique allowed the scientists to produce living pigs that are free of Pervs. About four months ago, 37 PERV-free pigs were born, 15 of which are still alive and thriving.

A major obstacle until now has been the cancer viruses embedded in pigs' DNA, which are capable of making the jump to human cells.

But other researchers say the risk of infecting humans with pig retroviruses is not that clear and that, on balance, unnecessarily editing the pig genes would add to the complexity and cost of a xenotransplant.

And the viruses could then be transmitted from infected human cells to other healthy human cells.

Scientists already use gene editing technology in such areas as agriculture and drug development, Sci-Tech Today wrote in an August 6 article. "If you need to knock [these viruses] out, this is the way to do it, no question", he says.

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