It is almost 10 years since scientists at Albert Einstein College of Medicine in New York succeeded in repairing stroke damage in rats by injecting their brains with stem cells.This particular treatment option is likely to raise hackles among pro-life groups because it utilizes stem cells taken from aborted fetus, rather than the unobjectionable use of adult stem cells.
Within six weeks they had become mature brain neurons, proving that it was possible to repair the brains of another mammal.
Over the next year up to 13 patients in total will be given progressively higher doses of stem cells as part of the PISCES trial. Doses will go as high as 20 million cells, said Prof Muir.
All the participants are men over 60 who have had ischeamic strokes - caused by a blockage of blood flow to the brain - and failed to respond significantly to treatment.
Strokes kill about 67,000 people a year in Britain, according to the Stroke Association.
Prof Muir said the stem cells in the PISCES study were grown from neural stem cells from a 12-week-old aborted foetus from the US.
The trial - carried out with the ReNeuron Group, which grew the stem cells in the lab - received UK regulatory approval in January 2009.
Still, it is worth noting that it has been more than a decade since researchers first carried out successful animal trials on stroke victims and there is no guarantee of success here. If it is successful, stem cell treatments for strokes could help tens of thousands annually around the world.
At the same time, a new drug may improve on the warfarin blood thinner commonly given to stroke victims.