Value of a soft cell

Stem-cell therapy is about to prove itself. Over the next few months, researchers will inject stem cells into the retinas of 12 people with a genetic condition that has slowly robbed them of their eyesight. The hope - and expectation - is that these people will begin to see again in 2011.

The cells, derived from human embryos, have the ability to develop into virtually any kind of cell in the body. The patients in the trial have faulty retinal cells that began to die off in early childhood. These cells are meant to supply nutrients to the photoreceptor cells that capture light; when they fail, the result is gradually degenerating vision. In many cases, the sufferers can do little more than see their hands in front of their face or perceive a difference between light and shade. An injection of 200,000 embryonic stem cells should reverse this because they will develop into healthy versions of the defective ones and restore the support system for photoreceptors.

Crucially for the reputation of stem-cell scientists, the trial can be halted at any stage. Because of their position on the retina, the cells can be seen with a microscope and removed, should anything untoward start to occur.

Scientists hope that the extreme versatility of embryonic stem cells will eventually help people suffering from a wide range of medical problems, from heart disease to Parkinson's. Yet there are also some unscrupulous scientists playing on - and profiting from - this hope.

Questionable stem-cell therapies have led to the death and hospitalisation of a number of patients this year. Among the deaths were two Koreans who indulged in "stem-cell tourism": their cells were prepared in Seoul but administered in China and Japan.

Such tourism is necessary because performing stem-cell therapy is illegal in South Korea, though perhaps not for long. The Korea Times reported last month that lawmakers, officials and entertainers were being offered illegal stem-cell treatments at reduced cost in exchange for help relaxing the Korean regulations.

In theory, administering stem-cell therapy is also illegal in China, but regulatory guidelines have yet to be drafted, so there is a window of opportunity for physicians willing to offer the treatment. In Japan, approval is required to perform stem-cell therapies but physicians are allowed to import stem cells for use in private practice. Until there is global agreement and enforcement of regulations, stem-cell tourism will continue.

The inevitable deaths and disappointments are likely to taint the reputation of stem-cell therapy for some time.

The science is still at its earliest stages, but this kind of therapy could offer us what looks like a series of miracle cures. It would be a disaster if proper trials or public acceptance were stymied because of profiteering.