Steven Rose: Don't expect miracle cures in stem cell research

There have been at least three major developments in the technologies of genetic engineering. First, the British Government has legalised stem cell research, the first country in the world to do so, and against a barrage of ethical criticism. Second, experimental clinical procedures designed to mitigate the effects of Parkinson's disease by injecting foetal material into the brain have gone badly wrong and have been terminated. Third, a group of clinicians and researchers have held an international meeting in Rome to announce their intention of proceeding immediately with human cloning.

So what might stem cells be used for? The press has made much of the possibility of using them to grow "spare parts", skin, muscle, heart or kidneys. Stem cells have also been proposed as a way of treating a variety of neurological disorders, including stroke, spinal injury and Alzheimer's disease. Stem cells could, it has been proposed, rectify macular degeneration, glaucoma, retinal detachment and diabetic retinopathy.

But before turning to that it is important to spell out the ethical problems associated with proceeding with stem cell research. If we accept that it is necessary to draw a clear line in the sand over which research and therapeutic intervention must not cross, and most of us do insist that this is the case, then where is it to be drawn? Cloning an entire human being, as proposed in the extraordinary circus convened in Rome a couple of weeks ago by the showman-like Dr Antinori and his US and Israeli partners, is for most of us entirely unacceptable, as it implies the use of a human as a means rather than an end, even were it technically possible and safe. And of course such gung-ho technophilia complete ignores the social context in which such a cloned human would be born and grow.

Since 1987 the use of foetal stem cells in the treatment of Parkinson's has been continuing on an experimental basis in Europe and the US. The work has been pioneered in Europe by Anders Bjorklund in Lund, in Sweden, in conjunction with researchers in Cambridge and at the Hammersmith Hospital in London.

However, all this techno-optimism was brought to a crashing halt in the middle of last month, when the results of the first full clinical trial using foetal material were published, involving some 40 patients. The therapy produced no benefit for patients over 60, and whilst some of the younger patients did improve, 15 per cent were actually worse off, with persistent finger chewing, uncontrolled jerky movements and loss of intellectual function.

The lesson is that there are no miracle cures. Like cystic fibrosis for gene therapy, Parkinson's for foetal and stem cell transplants are "best cases", the most likely ones to try for because of what is known about the biochemical causes of the condition, tissue access and other factors. Stacked up behind Parkinson's, enthusiasts claim, will be Alzheimer's and stroke. Yet these, because of the nature of the brain damage that results, are much less amenable to the stem cell approach. The problem, simply, seems to be one of control. The embryonic cells grow uncontrollably; too much dopamine is produced, and the consequences seem irreversible.

So should the research continue? Those opposed say no: the possible eventual good is far outweighed by the present ethical damage. Far better to continue to work on new drugs, or to explore the possible use of adult stem cells, derived presumably from the person suffering from the disease. Those in favour see no great ethical line being crossed, and the potential benefits are great.

With Dr Antinori and his crew hovering in the wings, offering their march to the glory of being the first to clone, and devil take law, ethics, scientific caution or hippocratic oaths, we shouldn't be too optimistic.