27 May 2013 Last updated at 00:01 ET By Pallab Ghosh Science correspondent, BBC News

Five seriously disabled stroke patients have shown small signs of recovery following the injection of stem cells into their brain.

Prof Keith Muir, of Glasgow University, who is treating them, says he is "surprised" by the mild to moderate improvements in the five patients.

He stresses it is too soon to tell whether the effect is due to the treatment they are receiving.

The results will be presented at the European Stroke Conference in London.

BBC News has had the first exclusive interview with one of the patients involved.

They are taking part in a small clinical trial involving nine patients in their 60s, 70s and 80s at Glasgow's Southern General Hospital to assess the safety of the procedure which involves injecting stem cells into the damaged brain part.

It is one of the first trials in the world to test the use of stem cells in patients.

Results to be presented on Tuesday show that there have been no adverse effects on the patients so far and there have been improvements to more than half participating in the trial.

However, at this stage it is not possible to say whether the improvements are due to the close medical attention the patients are receiving. It is well documented that the feeling of wellbeing resulting from such attention, known as the placebo effect, can have a positive effect on people's health.

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Stroke stem-cell trial shows promise