One step closer to using cloned pig organs in human transplants

Illustration by James Bareham  The Verge

Scientists in decades past experimented with transplanting chimpanzee organs into human patients but turned their focus to pig organs instead after finding them to be more suitable donor candidates. The study has shown that they can produce retrovirus-free piglets but moving onto pig organ donation is another step. The company said almost 118,000 people in the US need a life-saving organ transplant and every 10 minutes someone is added to the waiting list.

The shortage of human organs and tissues for transplantation represents one of the most significant unmet medical needs.

The WHO says while animals are a potential source of high quality, readily available live organs, xenotransplantation carries risks, especially the spread of known or unknown diseases. There were 33,600 organ transplants previous year in the us, and 116,800 patients on waiting lists and there are around one billion pigs in the world.

"Getting organs from animals - particularly from pigs, whose organs tend to be close in size and work similarly to human organs - could be the solution to that shortage", Business Insider says. In partnership with United Therapeutics, the group has already built a farm for gene-edited pigs.

The researchers, including famous Harvard geneticist George Church, used the powerful gene-editing tool CRISPR-Cas9 and the same technology used to clone Dolly the sheep to create healthy piglets that can't transmit harmful viruses. A team of global science is able to genetically modify the piglets so that their organs are more compatible for transplants in humans.

They then placed that cell into an egg, which developed into an embryo, which eventually became piglets. Porcine retroviruses (PERVs) are now one of the big safety barriers preventing us using pigs as organ donors.

"We now have the world's first ever PERV-inactivated pigs", Wei told Xinhua.

"It's quite a problem, when you move to so many targets", said Yang, the chief scientific officer at eGenesis.

However, even if PERVs are off the table, pigs will require other modifications so their organs won't be rejected by the human immune system or cause other harms - for instance, genes will prevent toxic interactions with human blood will need to be inserted. Today 15 of the piglets are alive.

In China alone, more than 300,000 patients are waiting for organ transplants but fewer than 10,000 surgeries are performed each year.

Genetically modified pigs are being engineered to grow human transplant organs, but the existence of Pervs has been a major stumbling block in the development.

Meanwhile Ian McConnell, from the University of Cambridge, said: "The use of human organs for transplantation only meets a small percentage of the total and growing number of individuals in desperate need of organ transplantation".



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