Six patients had human stem cells inserted close to the damaged part of their brain and have since witnessed improvements in the limb weakness they suffered as a result of their stroke.
In one case, a man given the treatment regained the power of speech after the stem cells were injected into his brain.
However, doctors have made clear that these are very early results of the clinical trial – a world first for neural stem cell therapy for stroke victims.
The trial is being conducted at the Institute of Neurological Sciences at the Southern General Hospital in Glasgow, and is being led by Glasgow University neurologist Professor Keith Muir.
He told the BBC: "So far we've seen no evidence of any harmful effects. We're dealing with a group of people a long time after a stroke with significant disability and we don't really expect these patients to show any change over time.
"So it's interesting to see that in all the patients so far they have improved slightly over the course of their involvement in the study."
The six patients suffered strokes between six months and five years before they were treated, and all had been left with limb weakness.
The patients were assessed using the National Institutes of Health Stroke Scale which ranked the first five patients with a median score of eight before the treatment and four points three months afterwards.
The sixth patient was treated less than three months ago. Six further patients will be treated as part of this Phase 1 trial.
Professor Muir said he was "intrigued" by the early results.
He added: "We know that if you're involved in a trial you are going to see patients change in behaviour, particularly if you're doing something invasive, so we need to be very cautious indeed in interpreting these results.
"However, that said, it is not something we'd anticipated seeing in this group of patients."
Further trials are needed to establish whether stem cells actually help the brain repair damaged tissue.
With the EU about to cut stem cell funding are we doing enough to find cures for debilitating events like strokes?