STEM cell research, we have long been told, should pave the way for revolutionary new treatments to help millions of patients around the world.
Yet despite the years of study and debate about the potential, therapies have been slow to materialise.
Even the head of the UK National Stem Cell Network has now conceded that stem cell research may never deliver new treatments.
Given the ethical controversy about the research – particularly the use of animal-human hybrid embryos – some have questioned whether it is worth pursuing the research any further without proof that it will actually benefit human health.
But researchers meeting in Edinburgh later this week for the first ever UK National Stem Cell Research Conference will very much be spreading the message that the science is producing results and experts must be allowed to continue to study stem cells in their many forms.
Lord Patel of Dunkeld, chairman of the UK National Stem Cell Network and chancellor of Dundee University, said the current signs were that research involving stem cells would lead to therapies for patients.
But he said there was also a chance such treatments could prove too risky for human use.
Speaking to The Scotsman, Lord Patel said it could be five to ten years before stem cell treatments were widely available, with trials starting shortly in the UK and US.
"But we have to be cautious," he said. "It may not deliver therapy for anything. We may find that stem therapy is quite a risky business.
"We had a lot of hype about gene therapy, and while we still use it in some cases it did not deliver the great promise we thought it would because of the side-effects. But the promise just now is great and we must continue with the stem cell science."
Stem cell research has risen up the agenda in the last month due to ethical concerns about the creation of so-called hybrid embryos.
The DNA is taken from animal eggs and replaced with genetic information from humans, making them more than 99.9 per cent human.
From these, scientists can create embryonic stem cells for research – those with the most potential because they have the ability to develop into many types of tissue. They argue that a shortage of human eggs for research means that such hybrid embryos are vital to speed up developments.
But the Scottish Catholic Church has condemned the research, with Cardinal Keith O'Brien saying such research was of "Frankenstein proportions" and was a "monstrous attack on human rights, human dignity and human life".
He urged MPs to vote against a Bill which would support scientists working with such embryos in the UK and several members of the Cabinet threatened to resign unless they were given a free vote when it comes before parliament in a few weeks.
Scientists pointed out that the research involved embryos no bigger than a few grains of sand, not allowed to grow for more than a few days.
But a spokesman for the Scottish Catholic Church said: "At one point, we were all just a small bundle of cells.
"At that stage, while not recognisably human, these cells are still human life." The Church also pointed out that, as yet, embryonic stem cell research had failed to produce any meaningful results.
Despite his own reservations that stem cell work may not live up to its hype, Lord Patel said he was hopeful of finding treatments for serious diseases such as diabetes, Parkinson's, motor neurone disease and even disorders such as Alzheimer's.
"Are there any signs that this could happen? Yes there are, particularly in animal experiments that suggest this might be possible," Lord Patel said.
"In terms of embryonic stem cell therapy, there is currently no such therapy that is available in a large number of patients.
"It is suggested that pretty soon in the US they may go to first phase clinical trials in humans using embryonic stem cells for repair of damage to the spinal cord.
"It is possible that the UK, within a year, might be able to go to first stage clinical trials using embryonic stem cells for age-related macular degeneration (an eye condition].
"If both of these which have shown early promise come to fruition we are talking about a serious number of patients being treated."
One area currently exciting scientists is research showing that adult stem cells can be genetically manipulated to take them backwards so they behave like embryonic stem cells.
Known as induced pluripotent stem cells (IPS cells), the creation of such cells means that researchers will be less dependent on embryos to harvest the most useful cells for study.
Dr Willy Lensch, from the Children's Hospital in Boston, is among those working with such cells and believes they do hold huge promise, despite concerns they could be more at risk of cancer.
He said the aim was now to reduce the number of genes used to create the IPS cells to reduce the risk of a cancer side-effect.
So far his team have taken adult cells and turned them into stem cells for diseases such as juvenile diabetes and Down Syndrome.
Dr Lensch, who will address the Edinburgh conference later this week, said he hoped to learn a lot more about disease from studying such stem cells.
"My own specialism is to understand the genetic basis of disease and I believe there are a cornucopia of opportunities to use this science to increase our understanding and eventually lead to new treatments."
Dr Lensch said he had confidence that stem cell research would eventually lead to new treatments for patients.
"I think there is a lot of evidence to suggest that it will get somewhere.
"I could not guarantee to anyone that this work will actually lead to improvements in disease as a definite.
"But there are precedents already set which suggest the potential of stem cell science."
And yesterday, scientists in the US revealed they have been able to use skin cells re-programmed to act like embryonic stem cells to ease the symptoms of Parkinson's disease in rats.
Lord Patel said it was vital that scientists had every method possible at their disposal to study stem cells – including hybrid embryos – to make sure the potential was not lost.
SCIENTISTS around the world are exploring potential uses for stem-cell therapy. Here are some that are showing promise:
• A team in the UK are attempting to restore vision in people with age-related macular degeneration – the leading cause of blindness – using cells from patients' own eyes. Larger trials are planned.
• Researchers in the US are hoping to start trials using embryonic stem cells to treat patients with spinal-cord injuries.
• Scientists at the University of Nottingham are experimenting with stem cells in the hope of developing heart cells to treat patients who have suffered a heart attack. A billion of these cells would be needed for treatment. Currently they are only to create the cells in their millions.
• Researchers in Edinburgh and several other places are trying to harness the potential of stem cells in treating degenerative diseases such as motor neurone disease.
• As well as eventually being used in therapies, researchers hope that tissue created from stem cells could be used to test new drugs without having to use patients as guinea pigs. This could help speed up new treatment development.
• Some research suggests stem cells could be directed to become eggs or sperm to help patients who are infertile.