Six days after the birth of her twins 20 months ago, Samantha Panting suffered a massive stroke. Aged just 30, she was left partially paralysed and unable to talk - with five children under seven to care for.

Although she made an almost complete recovery, since then she has had three more strokes. "I just couldn't believe it," she said. "I thought only older people suffered from strokes."

Today Panting, from Thornbury near Bristol, is forgetful because of the damage the strokes have done to her short-term memory; her right hand is also weak. Another stroke would cause more deterioration. Although the attacks seemed to have been triggered by her pregnancy, she knows she could be struck down again at any time and fears not being able to play a full role in her children's lives.

Last week MPs gave the go-ahead to controversial research which offers hope to Panting, to thousands of other stroke victims and potentially to millions of others suffering from acute conditions and degenerative diseases.

This research, which uses cells from human embryos, could offer the prospect of a cure for cancer and a way of repairing vital organs such as the liver and heart. It could herald a whole new medical era.

For Panting and her family, stem cell therapy could not only repair the existing damage to her brain, it could also prevent another more devastating stroke. "My biggest fear is being stuck in a wheelchair," she said.

STEM cells are the raw material of life. About 100 stem cells make up a human embryo when it is only a few days old. These cells are special because they have the capacity to develop into all the other cells in the body. They can become blood, bone, brain and even nerves under the direction of as yet unknown genes which control the production of specific protein-based growth factors.

Scientists are beginning to discover what these chemical growth factors might be, which make cell repair and growing new organs possible.

New brain cells could cure Parkinson's and Alzheimer's disease and even help to prevent strokes in people such as Panting. From stem cells, new nerves could be grown to treat paralysis; new lung linings could be grown for cystic fibrosis sufferers; diabetes, blindness and innumerable other conditions could become curable. The first treatments could be available within five to 10 years.

Stem cells for research are created from artificial embryos, which are made by inserting a cell nucleus from the patient to be treated into a donor human egg. One of the problems facing researchers is the shortage of such eggs, which have to be extracted from women during an unpleasant operation.

To create cells which might help a patient such as Panting, a nucleus from any cell in her body would have to be implanted in a donor egg. This "embryo" would form the basis of the stem cell culture which could be grown into "repair" tissue in the form of new cells for her brain.

According to the Stroke Association, these new brain cells, when injected into her brain, could return the full function to her right hand and perhaps to her short-term memory. The association cautions, however, that the technology is likely to be most effective if it is administered within six to nine months of the original stroke.

Such miraculous cures sound like the preserve of Star Trek. The problem is that many people feel uneasy about harvesting the essence of potential human lives.

In agreeing that this research could take place, parliament recognised these fears and decreed that only embryos less than 14 days old may be used. Barnoness Warnock, the philosopher and ethicist who has led several government committees on these issues, explained the importance of this cut-off point.

"After 14 days, the embryo is to all intents and purposes a child," she said. "Before that I don't think there's anything morally dubious about using it at all because the cells are not differentiated; some will form an embryo, some will form the placenta.

"It's very difficult to think of that collection of cells as an identifiable human being; there is no question of it feeling any pain because the beginnings of the central nervous system don't occur until 14 days after fertilisation. At present the law criminalises the use of human embryos in research after 14 days. That won't change."

THIS argument was put forward by Yvette Cooper, the junior health minister, in the House of Commons last week. MPs on a free vote decided overwhelmingly in favour of research with 366 for, 174 against. But those who disagree - predominantly Catholics and some Conservatives - do so violently.

"You are talking about stem cell research using cloned human beings," said Professor Jack Scarisbrick, chairman of the anti-abortion group Life. He said putting a nucleus from one of Panting's cells into a donor egg is the same as cloning a human being and should not be allowed.

"It's a momentous step to be taking. The implications are mind-blowing and we should not be doing this casually. We are generating human beings with the deliberate intention of killing them and the end can't justify the means. We are all in favour of stem cell research - providing the stem cells have been ethically obtained," he said.

Dr Helen Watt, a medical ethicist and research fellow with the Linacre Centre for Healthcare Ethics, a Catholic bioethics centre, said: "We would be opposed to getting stem cells from embryos because you kill the embryo when extracting the cells. If you produce the embryo just to harvest tissue you are using its life as a stage in producing a pharmaceutical product."

Scarisbrick and Watt, among others, argue that stem cells can be obtained from sources other than embryos. In Sweden the cells are taken from aborted foetuses; in other countries, including America, stem cells are harvested from blood cells in the umbilical cord at the time of birth, or are extracted from adult tissue such as bone marrow.

The exception is Germany, where all stem cell research is banned because of the spectre it raises of Nazi eugenics.

The problem with these other methods of obtaining stem cells, however, is that stem cells from adults are often already partly "differentiated" into specific tissue forms. This makes them more difficult to control.

Professor Nick Wright, vice-principal for research at Imperial College school of medicine, London University, has done work which shows how adult stem cells from bone marrow could be used to form livers. He said this has been wrongly seized upon by pressure groups arguing against embryonic stem cell use.

"Adult stem cells have a limited repertoire," he said. "Embryonic stem cells can turn into anything - they are much better. The problem for scientists is in cracking the problem about directing them into the right tissue differentiation pattern. If we can do that, the possibilities are endless."

Stem cells were discovered 20 years ago in the laboratory of Martin Evans in Cambridge. Scientists working with mice discovered that by putting embryos into a different nutrient, the cells would go on dividing indefinitely and would not start to form the tissue for a baby mouse.

Since then researchers have begun to discover the hundreds of chemicals made by the embryo itself which are needed to turn stem cells into the different types of tissue.

Robin Lovell Badge, now a senior geneticist at the National Institute of Medical Research in London, recalled the excitement among the Cambridge team in 1980.

"There were lots of discussions about how fantastic it would be if we could get these stem cells from humans and use them to cure disease, but we didn't know if it would be possible," he said.

Attempts to procure stem cells from rats, rabbits, sheep and cows all failed. It was only three years ago that Jamie Thompson, at the University of Wisconsin, managed to cull stem cells using leftover embryos from IVF clinics. He licensed his invention to the Geron Corporation, which is now the world leader in stem cell science.

"We are trying to create a universal donor stem cell line that can be used by anyone without the risk of tissue rejection," said Tom Okarma, Geron's president. "We believe living cells will replace pills for illness in the 21st century. You would simply have universal donor cells frozen and stored in pharmacies to be prescribed for patients."

Okarma believes the first use of stem cells will be in the repair of spinal injuries or to treat degenerative brain diseases such as Parkinson's or Huntington's. But after realising the commercial potential, the company is focusing on heart failure. There are half a million Britons suffering this weakening of the heart muscle, which often follows a heart attack. Geron can already manufacture cardiomyocytes, one of the building blocks of heart muscle, using stem cells as the raw material.

British experts predict that research on brain cells will be the most fruitful and could help the 130,000 Parkinson's sufferers in this country within 10 years. Scientists in Sweden have already achieved dramatic results by injecting foetus stem cells directly into patients' brains. But again the ethical question is raised. Cells from six aborted foetuses are required to treat just one person - making the procedure both distasteful and prohibitively expensive.

HOWEVER, the real problem dogging this technology is not the ethics, or the cost, but simply how little is known about the growth factors needed to stimulate and control the production of different forms of tissue. David King, a geneticist who leads the Campaign Against Human Genetic Engineering, points to the development of cancerous tumours known as teratocarcinomas. These occur when cell multiplication goes haywire and creates a grotesque tumour made of muscle, tendons, internal organs, tufts of hair, teeth and even tiny fingers or arms.

"You do not have to come from the anti-abortion pro- lifers' camp to see that once you start using embryos as a source of biological raw material you are degrading their moral status," he said.

Lewis Wolpert, professor of biology as applied to medicine at University College London medical school, disagreed. "If you accept in vitro fertilisation [IVF] which involves creating and destroying embryos, you can't possibly be against the therapeutic cloning of stem cells," he said.

Panting and millions like her are waiting to see if the problems can be overcome. "If this research could prevent me having another stroke, it would be a life saver for me and my children," she said.

(From HealthNews.com)