He has been accused of playing Frankenstein and of sacrificing lives to benefit others, but Miodrag Stojkovic has no qualms over his work. He tells Nick Morrison why his conscience is clear.

"PEOPLE are thinking we are taking small babies and we are killing these babies and we are producing clone babies," Miodrag Stojkovic shakes his head with a smile, before adding: "We don't play with human life."

Dr Stojkovic is used to dealing with such accusations. As leader of the team given the first UK licence to carry out cloning on human embryos, he has been at the centre of the fiercest scientific debate since test tube babies more than 20 years ago.

When the Human Fertilisation and Embryology Authority granted the licence over the summer, pro-life groups called the decision "deplorable" and "perverse". One said the scientists were sacrificing one life for the benefit of others, while Dr David King, of Human Genetics Alert, said it was "scientifically irresponsible" to do the groundwork for those who wanted to clone babies.

For Dr Stojkovic, all this may come with the territory, but he has an unswerving belief in what he is doing.

"When somebody asks whether I have a clear conscience, I'm somebody who is trying to develop something to fight diseases. My conscience is clear.

"At the stage when organ transplantation was proposed, people who were against this thought doctors would go outside in the street to kill people to take tissues from them. What you learn is you can't make all people happy," he shrugs.

When the tall 40-year-old Serbian first arrived at Newcastle's Centre for Life two years ago, he was working alone, with just a microscope and an incubator for company. Now he has a team of 17, who will soon take over an entire floor at the centre's Bioscience department.

And in those two years he has narrowed the gap between the UK and the rest of the world, which had a four-year head start in therapeutic cloning, so that Newcastle is now recognised as one of the leading centres for research into his field.

But although his work has been given the handy tag of cloning, he says it isn't really cloning at all. Rather it is nuclear transfer, a technique used to develop human embryonic stem cells.

It works by removing the genetic material from a human egg cell, and replacing it with the genetic material of a patient. This cell then divides into stem cells, which are cells with the potential to develop into almost every type of human cell, including nerve cells, heart cells and pancreatic cells.

These cells can then be injected back into the patient, where they replace cells which have degenerated. So if a patient suffers from type one diabetes, pancreatic cells are injected to replace those which are no longer working; for Parkinson's disease, it would be nerve cells; for heart disease, it would be heart cells.

And because the new cells have been made with the patient's genetic material, there is no fear of rejection, and therefore no need for anti-rejection drugs and their unpleasant side-effects.

Researchers in the US have already cured a pig of heart disease using human embryonic stem cells, and scientists have also seen benefits in rats and mice suffering from Parkinson's. If it works in humans, the potential benefits are enormous.

"If this will work this will change medicine completely. This is something like a revolution in medicine. At the moment we are curing the effects, not where the disease comes from," Dr Stojkovic says.

"We will not cure the symptoms, we will cure why this disease appears. And if it works in a pig, why should it not work in a human?"

He says it is important not to raise false hope - the technique cannot cure many types of cancer, and is ineffective against diseases caused by viruses, such as Aids - but for degenerative diseases, those caused by cells no longer working, such as type one diabetes, Parkinson's, Alzheimer's and heart disease, it offers real hope.

While parts of the process are well understood, there is much work still to be done. The Newcastle team is looking at the optimum time to remove the genetic material from the egg and replace it with that of the patient, and at how the stem cells can be nurtured to produce the right sort of cells, nerve cells, heart cells or whatever.

Vitamin A helps the stem cells to develop into nerve cells, but the full range of what conditions produce what cells has still to be understood, and Dr Stojkovic's team is also looking at ways of nurturing these cells without using animal material, because of the danger that animal diseases could be passed on.

"There is already some speculation that we will be able to use human embryonic stem cells in the next five years, but I don't think you could say exactly when this will happen.

"Everything happens first in a plastic dish. The next stage is to see if there is an effect on animals, then a pre-clinical trial. If I say five years it may be too long, but nobody wants to give false hope," he says.

The principal ethical concerns come from the use of the eggs themselves, and the possibility that it could lead the way to human cloning, but Dr Stojkovic has few qualms on either score.

The eggs come from the IVF clinic at Newcastle Fertility Centre, are both fertilised and non-fertilised, and are surplus to requirements. The parents are asked permission for the eggs to be used.

"Normally they would be discarded, they would be destroyed. Our way is not to destroy them: we prefer to use them for scientific purposes. What is better: to discard them or to develop human embryonic stem cells? If there is some fear that we are destroying potential life, I can understand this fear, but we are trying to help the people who are with us, who are parts of our lives and parts of our family," he says.

The danger that someone could use legitimate research to study human cloning for reproductive purposes - banned in the UK under penalty of ten years in jail - should also not be a bar to his work, he believes.

"Always we have the danger that it could be used by non-serious scientists - you call them maverick scientists. But we all know that death is part of life. There is no way to replace people with cloning. Nobody can turn the clock back, give the same experience, the same environment to create this person once again.

"We respect that some people are not happy with what we're doing but there is nothing to fear about the cloning of human beings. Nobody thinks this is something we need and more important is the fact it is not allowed and we're all happy and agree that it is not allowed."

He says it is because he understands the concerns people have that he wants his work to be conducted in the open, with no fear that it is taking place behind closed doors. As part of this approach, along with Professor Alison Murdoch of the Newcastle Fertility Centre, he will be giving a public lecture on his work at the Life Centre tonight.

"We want to explain to people and to discuss with people, to convince them they have to make up their own opinion whether this is ok or not," he says.

But this desire to explain also comes from his own belief in his work and its potential to help transform so many lives.

"You are curing diseases at the source, therefore it is important and therefore people are completely excited to do this kind of job," he says.

"It is really amazing. When I am speaking to you now I am recognising how amazing it is. I know all these things, but..." he tails off in wonder. "You see beating heart cells in a plastic dish. Work is so exciting. We're very happy and very glad and we feel privileged to do this."

* Dr Stojkovic and Professor Alison Murdoch will give a free public lecture on therapeutic cloning at the Centre for Life, Newcastle, tonight at 6pm.