Stem cell treatment could help stroke victims survive serious brain damage, the first human trial of its kind has suggested.
The pilot study, conducted by doctors at Imperial College Healthcare NHS Trust and scientists at Imperial College London, saw five stroke victims injected with stem cells directly into their damaged brain within seven days of a stroke.
The stem cells were taken from the patients' own bone marrow.
The scientists said it showed "promising results", with all the patients showing improvements in disability within six months - something that had only previously been shown in animals.
Four out of five patients had the most severe type of stroke, which only four per cent of people are expected to survive and lead independent lives after six months.
In the trial, all four were alive and three were independent after six months.
Professor Nagy Habib, from the department of surgery and cancer at Imperial College London, said: "These are early but exciting data worth pursuing.
"Scientific evidence from our lab further supports the clinical findings and our aim is to develop a drug, based on the factors secreted by stem cells, that could be stored in the hospital pharmacy so that it is administered to the patient immediately following the diagnosis of stroke in the emergency room.
"This may diminish the minimum time to therapy and therefore optimise outcome. Now the hard work starts to raise funds for this exciting research."
Over 150,000 people have a stroke in England every year, with survivors affected by a wide range of mental and physical symptoms, and many never recover their independence.
While stem cell therapy is seen as a potential new treatment for stroke victims, its exact role is yet to be clearly defined.
The trial, which found the therapy was safe, also suggested that early intervention was key.
Dr Soma Banerjee, a lead author and consultant in stroke medicine at the Imperial College Healthcare NHS Trust, said: "This study showed that the treatment appears to be safe and that it's feasible to treat patients early when they might be more likely to benefit.
"The improvements we saw in these patients are very encouraging, but it's too early to draw definitive conclusions about the effectiveness of the therapy.
"We need to do more tests to work out the best dose and timescale for treatment before starting larger trials."
Dr Paul Bentley, from the department of medicine at Imperial College London who also worked on the study, said: "This is the first trial to isolate stem cells from human bone marrow and inject them directly into the damaged brain area using keyhole techniques.
"Our group are currently looking at new brain scanning techniques to monitor the effects of cells once they have been injected."
The findings of the study, funded by OmniCyte and the National Institute for Health Research Imperial Biomedical Research Centre, are published in the journal Stem Cells Translational Medicine.