FIVE patients left seriously disabled by strokes have experienced small signs of recovery since entering a Scottish stem-cell therapy trial.
Professor Keith Muir, from Glasgow University, said the results were "not what we would have expected" from the group of patients, who had previously shown no indications of their conditions improving.
He stressed it is too soon to tell whether the effect is due to the treatment they are receiving.
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The trial involves injecting stem cells directly into the damaged parts of the patients' brains, with the hope they would turn into healthy tissue or kick-start the body's own repair processes.
Nine patients, in their 60s, 70s and 80s are taking part in the trial at Glasgow's Southern General Hospital to assess the safety of the procedure.
Among the patients to have shown improvements is former teacher Frank Marsh, who had a stroke five years ago.
The stroke left him with poor strength and co-ordination in his left hand, and poor balance. He needs a walking stick to help him move around the house.
The 80-year-old took part in the trial at Glasgow's Southern General Hospital, and said he had seen improvements in the use of his left hand.
Mr Marsh said: "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.
"It still feels fairly weak and it's still a wee bit difficult to co-ordinate but it's much better than it was."
Mr Marsh said he hoped the improvements would continue, adding: "I'd like to get back to my piano. I'd like to walk a bit steadier and further."
After the injection of stem cells into the damaged area of his brain, his balance and mobility also improved.
His wife Claire said: "He had reached a plateau and wasn't really improving [after his stroke].
"But following the operation he is able to do things he couldn't do before, such as make coffee, dressing, and holding on to things."
The study involved patients who suffered strokes some time ago and showed no sign of making further improvement.
Mr Muir said he and colleagues were pleased and encouraged by the data from the study.
He said: "The data to date identify no safety issues with the ReN001 treatment – which is the primary focus of this phase one trial. The evidence of functional improvement requires further investigation in a suitably designed phase two efficacy study and we look forward to being a principal clinical site in that study when it commences."
Mr Muir said the results were "at the present time not what we would have expected in this group" but he said they were far from being able to say whether the improvements were connected to the cell therapy.
He added: "We know some of the cells will survive and potentially turn into relevant tissue.
"We also suspect a large part of what we do is kick-starting repair processes that are already present in the body.
"So there is probably a mixture of things going on. Quite what it is that's happening in the patients, we won't know for some time to come."
The stem cells were created 10 years ago from a sample of nerve tissue from a foetus.
The company that produces the cells, ReNeuron, is able to manufacture as many stem cells as it needs from that original sample.