Doctors have injected neural stem cells into a man's brain as part of the world's first clinical trial of this type of stem cell in stroke patients.
The former truck driver, who is in his 60s, was severely disabled by a stroke 18 months ago and requires continuous care from his wife.
Doctors injected around two million neural stem cells into a healthy region of his brain called the putamen, close to where neurons were damaged by the stroke. They hope the injected cells will release chemicals that stimulate new brain cells and blood vessels to grow, while healing scar tissue and reducing inflammation.
The team, led by Professor Keith Muir at the University of Glasgow's Institute of Neuroscience and Psychology, expect to treat 11 more male patients aged between 60 and 85 in the trial, using progressively higher doses of five million, 10m and 20m cells.
The injections are being given to patients who have suffered ischaemic stroke, the most common type, caused by a blocked blood vessel in the brain. The operation requires a general anaesthetic and patients will be monitored for two years to see whether the procedure is safe and has any beneficial effect on their quality of life.
John Sinden, chief scientific officer at ReNeuron, the Surrey-based company that developed the cells, said of the first patient to receive the experimental injection: "He is really looking for some level of independence."
Animal studies suggest the cells are safe and effective at healing brain injuries. "We see regrowth of blood vessels, the generation of new neurons, a reduction in scarring and inflammation in the brain," said Sinden. "There are a range of things that happen that are best described as the brain to some extent healing itself."
One concern over stem cell therapies has been whether they might cause cancer, but Sinden said the neural stem cells used in the latest trial appear not to form tumours. They are derived from brain cells taken from a 12-week-old foetus in the US. At this stage of their development, the cells are committed to becoming brain cells.
The trial, known as the Pilot Investigation of Stem Cells in Stroke (PISCES), is primarily aimed at judging the safety of the stem cell injections, but doctors will use brain imaging and video recordings of the patients walking to assess whether the therapy helps them to recover from stroke.
The PISCES study is not the first to inject stem cells as such into patients' brains; the distinction is that it is using neural stem cells. In 2006, for instance, doctors in Oregon transplanted foetal stem cells into the brains of children with an incurable and fatal disorder called Batten disease. The phase one trial found that the treatment was safe.
Anthony Hollander, professor of rheumatology and tissue engineering at Bristol University, said: "Successful stem cell therapies will come from painstaking research and carefully planned clinical trials. This stroke trial is based on good research and careful planning. It's far too early to know if the treatment will be successful, but the very fact that the trial is now under way is a milestone for UK stem cell research."
• This article was amended on 30 November 2010. The original suggested that the Glasgow trial was the first to test stem cells in stroke treatment. This has been corrected.
