Human organs for transplant are being grown inside sheep and pigs

More than 50 sheep and pigs have been implanted with human-animal hybrid embryos with the aim of them developing into fully functional human hearts, livers and other major organs.

Although these techniques have yet to arrive in Britain, the Government’s animal research advisers are expected to make them legal when the first full guidelines are published this week, The Times reported.

The experiments rely on a cutting-edge fusion of technologies, including recent breakthroughs in stem-cell biology and gene-editing techniques. 

By modifying genes, scientists can now change the DNA in pig or sheep embryos so they are genetically incapable of forming a specific tissue.

Then, by adding stem cells from a person, they hope the human cells will take over the job of forming the missing organ, which could then be harvested from the animal for use in a transplant operation.

Daniel Garry, a cardiologist who leads a chimera project at the University of Minnesota, said: ‘We can make an animal without a heart. 

'We have engineered pigs that lack skeletal muscles and blood vessels.’

The US research was carried out at the National Institutes of Health in Maryland. 

Twenty livestock have been impregnated in the past year while a further three pregnancies are said to have taken place in other countries. But there are fears that the hybrids will make the animals too human, developing patches of human hair, human reproductive cells or higher intelligence.

Other kinds of human-animal chimeras are widely used in scientific research, including mice given a human immune system.

The NHS has previously said human-animal chimera technology could save hundreds of lives every year. 

In 2014, 429 people died while on the organ transplant waiting list.

(dailymail.co.uk)