According to a well known fertility specialist and broadcaster in the UK, the promise of embryonic stem cell research has been oversold by scientists.
The expert, Lord Winston, says the possible benefits of embryonic stem cells and the speed with which they will help patients have been exaggerated to persuade politicians and the public to support the controversial field of research.
Lord Winston, who is president of the British Association for the Advancement of Science, believes that experiments with such cells are important and could eventually lead to ground-breaking advances in medicine and biology, but he is concerned, that these have been exaggerated for political reasons.
This he believes will ultimately lead to a backlash against ES research when it fails to provide new treatments for Parkinson's disease, diabetes and other illnesses within the next few years.
Speaking at the BA's annual Festival of Science in Dublin, Winston has urged scientists not to overstate the importance of their work and hype up the importance of embryonic stem cells.
Winston says he views the current wave of opinion about embryonic stem cells with 'growing suspicion', even though the focus on stem-cell biology is a very important focus.
He feels there is an air of desperation in the attempt to get appropriate legislation passed, and fears that some politicians are convinced that the near future will see the transferrence of stem cells to cure diseases such as Alzheimer's.
But other experts in the field dispute this and say the hype in the field has not been created by the scientists as none claim that therapies are going to be with us tomorrow, and feel Winston is overreacting.
Lord Winston's concerns appear at the same time as a new study shows that colonies of human ES cells can accumulate genetic changes that could affect their behaviour.
The study led by Aravinda Chakravarti, of Johns Hopkins University in Baltimore, Maryland, underlines the need for careful testing before the cells can be used in medical therapies.
Apparently some of the DNA changes seen are typical of those observed in some cancers.
This suggests a risk in transplanting them into patients, though it could also give scientists an insight into tumour development.
ES cells are master cells that can give rise to any form of tissue in the human body, and might thus be used to grow replacements for the cells that are lost or damaged in conditions such as diabetes, Parkinson's and spinal injury.
Embryonic stem cells were first isolated by a team led by Dr James Thomson, of the University of Wisconsin, in 1997; their use is opposed by anti-abortionists, as extracting them involves destroying human embryos.
The cells provide good laboratory models for studying cell biology and the progression of diseases, including cancer as well as the possibility of therapeutic cloning.
This involves taking ES cells from embryos that are clones of the patients who need treatment.