WASHINGTON, 22 June 2006 - U.S. scientists have for the first time used embryonic stem cells and a concoction of chemicals to help paralysed rats walk - a groundbreaking feat that may help cure ailments such as Lou Gehrig's disease.

The research sponsored in part by the U.S. National Institutes of Health (NIH) may also eventually aid humans who suffered partial paralysis from spinal cord injuries and muscular atrophy.

But the study, published in the July issue of The Annals of Neurology, warned that years of work lay ahead before it could be applied to humans. The research was initially conducted with cells from mice and must still be tested on larger animals to see if results are compatible.

It marks the first time researchers have used neurons from embryonic stem cells found in the spinal cord to restore some muscle function in paralysed animals.

The partially paralysed rats regained enough muscle strength in their limbs to walk again after receiving the injection of stem cells along with a chemical concoction that included the anti-depression drug rolipram.
Muscles rejuvenated in 75 per cent of the rats after six months of treatment.

"This work is a remarkable advance that can help us understand how stem cells might be used to treat injuries and disease and begin to fulfill their great promise," said Elias Zerhouni, director of the National Institutes of Health.

The project's chief researcher, Douglas Kerr of The Johns Hopkins University of Medicine, said the study provided a "recipe" for using stem cells to restore the nervous system.

"It raises the notion that we can eventually achieve this in humans, although we have a long way to go," Kerr said.

Embryonic stem cells are master cells that can be grown into any of the 200 cell types in the human body and thus replace defective tissue. Scientists believe they could be used to fight illnesses including cancer, diabetes and Alzheimer's disease.

The research remains highly charged politically because the embryo is discarded after its stem cells are extracted. Scientists would need to develop human embryonic stem cells to learn if they will work in the same way as the mouse cells.

But first the team plans to work on larger animals, and Kerr's group is currently developing a pig model because no large animal model currently existed for motor neuron degeneration.

Scientists said the study was particularly important because it definitively showed that embryonic stem cells had to be used together with a mix of other chemicals to prompt muscle tissue to regenerate neurons.

Earlier work was based on the premise that stem cells alone might do the job.

"This research represents significant progress," said the study's program director, David Owens of the NIH National Institute of Neurological Disorders and Stroke.

"It is a convergence of embryonic stem cell research with other areas of research that we've funded, including work that uses combination therapies."