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Stroke tests go ahead despite US warning Special report: the ethics of genetics James Meek, science correspondent Monday April 16, 2001 The Guardian A British firm has vowed to press ahead with plans to implant genetically modified human stem cells into the brains of stroke victims, despite the severe side effects experienced by Parkinson's disease sufferers in a comparable trial in the US. The firm, ReNeuron, based in Guildford, Surrey, has been encouraged by new research on rats which suggests the animal's modified cells are capable of repairing different kinds of brain damage. In the US research, scientists drilled holes in patients' heads and inserted tiny amounts of foetal brain tissue inside, hoping they would manufacture a vital natural brain chemical, dopamine, which is depleted in Parkinson's sufferers. Early results from those trials, reported last month in the New England Journal of Medicine, showed that while older patients were unaffected and some younger patients improved, a small number began to writhe, jerk, flail and move their jaws uncontrollably. Martin Edwards, chief executive of ReNeuron, said: "We are quite determined to go forward into trials. "My view of the New England Journal of Medicine paper is that it has taken the field forward. It has provided some objective evidence about both risk and benefit which is a step along the way." ReNeuron has yet to apply to regulators to start trials, and has not begun recruiting volunteers, but Dr Edwards said the first phase would involve eight to 12 patients who had recently suffered a stroke. He said he did not believe it would be necessary for the first trial to repeat one of the most controversial aspects of the US Parkinson's study - giving some volunteers sham surgery. To create a control group, which had not been given the grafts but believed it had, the US researchers drilled holes in all of the patients' skulls and only put foetal material in some of them. Unlike the Parkinson's trial, ReNeuron's stroke trial will use stem cells multiplied in the lab rather than fragments of foetal brain. The company claims this technique will enable it to control the amount and type of cells implanted in patients' brains more precisely. In a further control measure, ReNeuron's cells contain a temperature- sensitive gene. At laboratory temperatures of 33C they divide and multiply, but in the hotter temperatures inside the human brain - 37C to 38C - they no longer divide. A stroke occurs when the blood supply to the brain is blocked. Of the 100,000 victims of first strokes in Britain each year, some 40,000 survive and experience varying degrees of paralysis and mental impairment. ReNeuron's research is aiming to help victims in the months immediately following a stroke, when the brain's natural repair mechanisms are struggling to put right the damage. Last week Helen Hodges, of the Institute of Psychiatry in London, told a meeting of the British Neuroscience Association that ReNeuron cells had improved movement and cognition in rats which had been given artificially-induced strokes. Dr Hodges, one of the founders of ReNeuron, and other researchers, used genetically modified mouse rather than human cells to implant into the rat's brains, but she said the results were an important proof of principle. Unexpectedly, the cells spread throughout the brain, rather than staying in one place, she said. "The stem cells do not remain clustered in the brain, like foetal grafts, but disperse, integrate and improve function even in aged animals," she added. "We expect that stem cells will prove to be far safer and more flexible for brain damage repair than primary foetal cells because they are unlikely to worsen symptoms, as recently reported in some Parkinson's patients." http://www.guardian.co.uk/uk_news/story/0,3604,473707,00.html ********* ---------------------------------------------------------------------- To sign-off Parkinsn send a message to: mailto:[log in to unmask] In the body of the message put: signoff parkinsn