Human organs are being grown in animals in the US in a controversial technique that is likely to be approved by the Home Office in Britain.

Dozens of pigs and sheep have been implanted with embryos which have both animal and human DNA.
It is hoped that when the hybrid animals are fully grown, their organs will be fully transplantable into patients without rejection because they carry human genetic material.

This week the Home Office’s Animals in Science Regulation Unit could publish the first guidance on the use of animal human chimeras. The committee is expected to say that such research will be heavily regulated, but allowed if it can show that the benefits would outweigh the harms.

There is currently a desperate organ donor shortage in Britain, mainly driven by medical advances which are saving more lives following accidents. Family members are increasingly refusing to give consent and more than 429 people died in 2014 waiting for a transplant. There are also concerns that the number of useable organs is dropping because donors are older and less fit. A quarter of organs are now taken from obese patients compared with one in eight a decade ago. The new technique could solve the shortage of hearts, livers and kidneys almost immediately.

Around 20 animals have been implanted with hybrid embryos at labs in the Salk Institute in California and the University of Minnesota over the past year according to the MIT Technology Review and dozens of further experiments have taken place in other countries. It is believed no animal has yet been brought to term and no papers have been published on the science.

The experiments involve taking pig and sheep and removing the DNA which allows them to form animal organs and replace it with human stem cells which create a human organ inside the animal.
“We can make an animal without a heart. We have engineered pigs that lack skeletal muscles and blood vessels,” says Daniel Garry, a cardiologist who leads a chimera project at the University of Minnesota.

Scientists already use human-animal chimeras in experiments, such as mice which are bred to have a human immune system. Martin Bobrow, a former professor of medical genetics at the University of Cambridge, said that work on chimeras could lead to ‘medical advances of considerable importance.’
“Without someone trying these experiments, we will not know whether the risks are huge, negligible or inbetween,” he told The Times.

Report by Sarah Knapton, Science Editor of The Telegraph.