Scientists in Newcastle set off a media firestorm in the U.K. earlier this week by announcing that they had created a human-animal hybrid--a cow egg whose nuclear DNA had been replaced by DNA from human skin cells. (The research has garnered little attention outside the British press.)

From the BBC report:

The Catholic Church describes it as "monstrous". But medical bodies and patient groups say such research is vital for our understanding of disease.

They argue that the work could pave the way for new treatments for conditions such as Parkinson's and Alzheimer's.

Lack of access to human eggs has been a major impediment to embryonic-stem-cell research, which is why scientists are turning to animal eggs. (See "Human Therapeutic Cloning at a Standstill").

From the BBC:

The Newcastle team say they are using cow ovaries because human eggs from donors are a precious resource and in short supply.

The hybrid embryos are purely for research and would never be allowed to develop beyond 14 days, when they are still smaller than a pinhead.

The scientists have been criticized for releasing their results through a news organization rather than through the traditional medium of a peer-reviewed journal.

From New Scientist:

Other scientists working in this area of research have had difficulty in growing cybrids past the 16-cell stage, so they will be looking forward to seeing the Newcastle team's results in a scientific journal--as will the rest of us. After the Woo-Suk Hwang scandal, you would think that scientists working in this most controversial of areas would be extra cautious about their results, but not, apparently, Armstrong's team.

Perhaps they want to take greater control of the media reporting of their work, given the extreme reaction last month to the creation of cybrid embryos shown by the leader of the Catholic Church in Scotland, Cardinal Keith O'Brien. But is it a good idea to bypass peer-review with announcements of such sensitivity? I'm not so sure.

A backgrounder on human-animal hybrids from the Guardian outlines previous hybrid research:

What is the situation in other countries?

Chinese scientists were reportedly the first to successfully create human-animal embryos. In 2003 a team at the Shanghai Second Medical University fused human cells with rabbit eggs. The embryos were allowed to develop for several days in a laboratory dish before being destroyed to harvest their stem cells. Later that same year, a US scientist, Panayiotis Zavos, announced he had created "human-cow" embryos that lived for around a fortnight and could theoretically have been implanted into a woman's womb.

In 2004 researchers at the Mayo Clinic in Minnesota produced pigs with hybrid pig-human blood cells. In 2005 Parkinson's disease researchers at the Salk Institute in San Diego reported they had created mice with 0.01% human cells by injecting about 100,000 human embryonic stem cells per mouse. Last year a Yale researcher, Eugene Redmond, led a project injecting millions of human neural stem cells into the brains of monkeys afflicted with Parkinson's disease. Many countries have banned this human-animal embryo research, including Australia, Canada, France, Germany and Italy.