US nod likely for growing human organs in animals

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

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 Committee will 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 and other countries, mainly driven by medical advances which are saving more lives following accidents. Family members of 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.

However authorities in American are worried that the animals may take on human traits and even higher intelligence.

''We are not near the island of Dr Moreau, but science moves fast,'' National Institutes of Health ethicist David Resnik said during a meeting in November.

''The spectre of an intelligent mouse in a laboratory cage somewhere screaming 'I want to get out' would be very troubling to people.''