As the first faltering steps are taken towards a new kind of medicine, Health Editor Barry Nelson looks at the debate surrounding human-animal embyos.

TWO years ago, Newcastle University scientists claimed a world first when they successfully cloned a human embryo. The Tyneside scientists removed the genetic material, or DNA, from a donated human egg cell and replaced it with the genetic material from another human being.

By passing an electric current through the egg they were able to produce stem cells - which have the potential to become skin, eyes, bones and every other type of human tissue. One of that successful team of scientists at Newcastle's Centre for Life was Dr Lyle Armstrong. Last night Dr Armstrong, a straight-talking Northumbrian, stepped into the limelight as the leader of a new team of scientists who will attempt to create controversial human-animal embryos.

Dr Armstrong, of Ashington, Northumberland, plays down some of the more excitable press reports about human-animal embryos. To Dr Armstrong, the use of abundant cow eggs rather than the extremely scarce donated human eggs simply means that he and his team will have plentiful raw materials to use in their experiments. Essentially, the creation of animal-human hybrids, which are 99.9 per cent human, is a means to an end.

Dr Armstrong - and another team headed by Dr Stephen Minger at King's College, London - sought permission from the Human Fertility and Embryology Authority to create animal-human hybrids in a bid to perfect a practical way of producing made-to-measure stem cells.

"We want to understand how the egg is capable of reprogramming a skill cell, or whatever human cell we choose to put into the egg," says Dr Armstrong, whose Albanian-born wife Dr Majlinda Lako is a joint team leader.

"If we can do that, if we can produce embryonic stem cells from that technique, then we can devise the means to do it in a test tube, or without having to bother animal eggs or human eggs in the first place," he adds.

He admits that the project will be "quite a tricky technique to get up and running."

But the Newcastle team are determined to try to keep their world lead in this promising and most cutting edge area of science. Ultimately, Dr Armstrong and his team hope to be able to come up with ways of using a sick patient's own cells to regenerate healthy tissue.

"There are some conditions, like Parkinson's Disease, which is the loss of particular brain cells, which we can't really treat very effectively at present," he says.

"If we can replace those brain cells effectively, having created them from a specific embryonic stem cell line then we can go a long way towards curing that disease. All we can do at the moment is try to replace some of the function of those brain cells with drugs and it doesn't really work all that well."

The aim of the research, assuming it gets the final go-ahead in November, is to produce healthy new cells which can be transplanted into the body.

"With Parkinson's Disease, for instance, the new cells would be injected into the brain at specific points. As they are essentially the same tissue as the patient they should then engraft and start to work in the brain."

There is certainly no intention of trying to produce living animal-human hybrids.

"What we will be working on will never be a person. It is strictly illegal, we wouldn't want to do it and anyway, IVF technology works very well so why would we want to produce a copy of a human being?"