A group of stroke victims who were given pioneering stem cell therapy have shown small signs of recovery.
The five patients had stem cells injected directly into damaged parts of their brains in the hope they would turn into healthy tissue or "kick start" the body's own repair processes.
Professor Keith Muir, of Glasgow University , said the results were "not what we would have expected", given the patients had previously shown no signs of improvement.
"There's probably a mixture of things going on," he told BBC Radio 4's Today programme. "Quite what it is that's happening in the patients, we won't know for some time to come."
Frank Marsh, 80, who is one of the patients taking part in the trial, said he hoped to be able to play the piano again after regaining much of the use of his left hand.
"I can grip certain things that I never gripped before, like the hand rail at the baths, with my left hand as well as my right," he said.
"It still feels fairly weak and it's still a wee bit difficult to coordinate but it's much better than it was."
His wife Claire added: "He had reached a plateau and wasn't really improving but following the operation he is able to do things he couldn't do before, such as make coffee, get dressed and hold onto things."
The stem cells used in the trial were created 10 years ago from a sample of nerve tissue taken from a foetus.
Earlier this month, scientists in the US said they had successfully used skin to generate embryonic stem cells .
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Stroke Victims Improve After Stem Cell Trial