Early tests of stem cells therapy in rat testing have shown they might be able to prevent or treat motor neurone disease (MND).
Researchers at John Hopkins University, Baltimore, said that rats that were treated with spinal injections of stem cells had prolonged lives than ones that did not.
They said their findings were "proof of principle" formerly believed of stem cells and surprising, to say the least.
Dr Vassilis Koliatsos from John Hopkins Medical Institution said: "We were extremely surprised to see that the grafted stem cells were not negatively affected by the degenerating cells around them.
"Many feared introducing healthy cells into a diseased environment would only kill them."
The rats had been first injected with the most common form of MND, known as Lou Gehrig's disease, before being injected a second time by the stem cells.
The next phase of study would see the rats grafted with stem cells along the full length of their spines to study upper-body effects.
Clinical application of the stem cell treatment is still a long way off, since many more tests are required before it could be considered safe.