Step aside, Frankenstein. A baboon has survived for over six months after receiving a transplanted pig heart with the help of some revolutionary gene-editing, marking a big step towards the possibility of pig-to-human organ transplantation in the not-too-distant future.

In a lab at the University of Munich in Germany, five baboons received transplanted pig hearts using a new method. Unfortunately, one died after less than two months due to complications, but two managed to live perfectly healthily for three months, with another surviving for exactly six months. The final baboon lived for longer than six months, before being euthanized. 

As you can imagine, xenotransplantation (transplantation between different species) can cause a violent response from the immune system, leading to the organs being rejected. However, a new approach has helped to overcome that. As reported in the journal Nature on Wednesday, the hearts had belonged to pigs that had undergone CRISPR–Cas9 gene-editing to reduce the risk of an aggressive immune response.

“The potential to solve the shortage of available human hearts for transplantation by using pig hearts has been an aspiration for scientists for more than 40 years but has proved to be a difficult journey,” commented Professor Jeremy Pearson, Associate Medical Director at the British Heart Foundation, who was not directly involved in the new study.

“The biggest hurdle is rapid rejection of the pig heart by the human immune system. This has been largely overcome by the development of genetically modified pigs, that have successively reduced this complication.”

Scientists have tried to pull off this feat before, only for the baboons to die after just 57 days. Another breakthrough was made in 2016 when researchers implanted a pig heart into a baboon, but the organ remained non-functional with the original heart still operational.

So, could the next step be pig-to-human organ transplantation? Not quite, but this new research is certainly heading in that direction.

The need for heart donors massively outweighs the supply from human sources, especially in the US and Europe where heart diseases are particularly common. If doctors could use genetically modified pig hearts instead, then the demand could easily be satisfied. However, there are still many hurdles to overcome before this becomes a reality.

“This new research takes us a step closer to the use of pig hearts in humans,” Professor Pearson added. “However, the results still fall short of the need for more extensive and longer-term studies before the first pig heart is transplanted into a human. 

“To be seriously considered for use in humans, studies will have to demonstrate greater success than a mechanical pumping device, and ensure that potential safety complications due to viral transmission from the transplanted heart to the recipient can be discounted.”

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