Stem cell hope for motor neuron disease

US researchers have managed to grow motor neurons, using human embryonic stem cells (ES cells), in the laboratory for the first time. The scientists, based at the University of Wisconsin, say their achievement could help research into motor neurone disease. It may eventually be possible to treat the condition using transplants of motor neuron cells, say the team, who reported their results online in the journal Nature Biotechnology.

Motor neurone disease (MND) affects movement by attacking the motor neurons - the nerves connecting the spinal cord to the muscles. As the nerves gradually waste away, people with the condition eventually lose all control over their voluntary movements. The causes of motor neurone disease remain largely unknown, although ten per cent of cases are linked to an altered gene inherited from an affected parent. Researchers are looking at ways to replace the lost nerve cells, and are also investigating what triggers their loss in MND.

ES cells, derived from early human embryos, have the ability to develop into almost any type of body tissue. But although scientists have managed to get human ES cells in the laboratory to grow into other kinds of nerve cells, they had not previously managed to grow motor neurons.

Su-Chun Zhang and Xue-Jun Li spent two years coaxing ES cells with different combinations of hormones and growth factors, until they came up with the perfect recipe for motor neurons. They found that the conditions under which ES cells can be directed in this way are extremely precise. 'You need to teach the cells to change step by step, where each step has different conditions and a strict window of time', said Zhang.

The researchers used one of ES cell lines approved by President Bush for use by federally funded scientists, created before 9 August 2001. Earlier this month, a new study found that all of the ES cell lines currently approved for use by US state researchers would be 'risky for use in medical therapies', as they are contaminated with mouse cell components. However, the Wisconsin team's work will be invaluable fto scientists looking at how diseases such as MND develop.

In September 2004, Professor Ian Wilmut, the scientist who led the team that cloned Dolly the sheep, applied for a licence to clone human embryos in order to carry out research on MND. He intends to look at cells from MND patients, and study their development in the laboratory, to see how the disease progresses. Such cells could also be used to test out new treatments for the condition.