In a move to curb the shortage of organ donors, scientists in the US are looking to grow human organs inside pigs. Researchers from the University of California have successfully injected human stem cells into pig embryos to produce chimeras (human-pig embryos).
At present, the chimeras have been allowed to develop for 28 days before being terminated. The tissues are then removed for analysis. The research is subject of a BBC Panorama programme Medicine's Big Breakthrough: Editing Your Genes.
If the embryo was allowed to develop fully, the idea is that it would have an organ made mostly from human cells - which could then be transplanted into a human patient. Researchers believe that this would solve the issue of organ transplantation, and will eventually decrease the death rate due to lack of organs.
Pablo Ross, a reproductive biologist who led the research, told BBC, "Our hope is that this pig embryo will develop normally but the pancreas will be made almost exclusively out of human cells and could be compatible with a patient for transplantation."
George Church, who has led similar research into the possible use of chimeras, also said in the future, organs grown inside pigs could be better than those from humans: "It opens up the possibility of not just transplantation from pigs to humans but the whole idea that a pig organ is perfectible. Gene editing could ensure the organs are very clean, available on demand and healthy, so they could be superior to human donor organs."
However, many oppose the experiment over fears that it could affect the animal's brain and behaviour. Julia Baines, Peta UK, has condemned the research and referred it as "Frankenscience", adding: "Creating human-animal hybrids is bad for people and worse for animals."
Peter Stevenson, from Compassion in World Farming, added: "I'm nervous about opening up a new source of animal suffering. Let's first get many more people to donate organs. If there is still a shortage after that, we can consider using pigs, but on the basis that we eat less meat so that there is no overall increase in the number of pigs being used for human purposes.