Scientists are growing human pancreas, hearts, lungs and other organs inside animals, bringing ideas from science fiction into the realm of medical science.
According to the The Guardian, the British National Health Service says almost 460 people died in the UK in 2016 while waiting for a suitable organ for transplant, while many who do receive treatment often have complications because of organ rejection.
Introducing human cells into animal embryos might not be the most conventional solution, but the technique could not only reduce waiting times, but also reduce or even discard the chance of an organ being rejected.
Dr Pablo Ross from the University of California, who is part of a team developing the technology to grow human organs in animals, told The Guardian, “Even today the best matched organs, except if they come from identical twins, don’t last very long because with time the immune system continuously is attacking them.”
Bruce Whitelaw, Professor of animal biotechnology at the Roslin Institute – where Dolly the sheep came to be – said that while we’re still a long way from effectively growing human organs in other species, the latest research is “an important step forward through starting to explore whether sheep offer an option for the exciting ‘chimeric’ project”.
Scientists are trying a different approach from xenotransplantation, which is to incorporate an organ that belongs to an animal into humans. While that’s certainly a valid possibility, researchers are exploring new alternatives – mainly, to embed human stem cells into animal embryos and use them grow genetically tailored organs.
Previous efforts have managed to grow a rat pancreas inside a mouse.
Dr Pablo Ross and his team revealed in 2017 they were able to introduce human stem cells into early pig embryos. The resulting embryos had a human cell out of every 100,000, which signifies a major breakthrough.
In Greek mythology, chimeras were monstrous fire-breathing hybrid creatures composed of several animal parts. The term is often used to describe something built from disparate origins, an appropriate word scientists are utilising to tag this novel methodology.
At the latest meeting of the American Association for the Advancement of Science last February, Ross’ team announced they improved their previous milestone with pigs, managing to achieve an even higher ratio of human to animal cells, this time with sheep.
The scientists said they produced sheep embryos with one human cell out of 10,000, beating their feat from last year by a factor of 10.
Ethics regulations currently allow scientists to let these chimeric embryos develop for 28 days, 21 of them inside the sheep.
But Dr Hiro Nakauchi of Stanford University, part of the team that managed the breakthrough with pigs and sheep, thinks longer experiments, perhaps up to 70 days – which would require additional permits from institutional review boards – would yield more convincing results.
The ultimate goal of their research is to achieve embryos with 1 per cent of human cells, an objective not far away if we take into consideration the rate at which their results are improving.