Stroke patients to receive brain-cell transplants

A clinical trial involving the transplantation of nerve cells from aborted foetuses into the damaged brains of stroke patients will begin next year, scientists announced yesterday at the British Association meeting in London.

A clinical trial involving the transplantation of nerve cells from aborted foetuses into the damaged brains of stroke patients will begin next year, scientists announced yesterday at the British Association meeting in London.

Medical researchers believe that foetal cells have the ability to develop into the fully mature nerve cells of the adult brain, enabling stroke patients to make a remarkable recovery from what has until now been an incurable condition.

John Sinden, a former researcher at the Institute of Psychiatry in London and chief scientific officer of ReNeuron, the company established to develop the technique, said that animal studies had shown that it is possible to recover well from a stroke, or blood clot on the brain, which can cause permanent paralysis.

Dr Sinden said that he was isolating the important "stem cells" of the foetal brain, which have the ability to develop into any of the three major types of brain cell. He will apply for ethical approval for a clinical trial involving a dozen stroke patients to begin at the end of next year.

One of the central dogmas of medical science is that a damaged brain is unable to repair itself, unlike most other organs of the body, because of the inability to harness the power of stem cells. More recent research, however, has questioned this assumption.

Dr Sinden said: "The brain is a highly specialised organ and it seems to have lost the capacity to use stem cells. Because of its specialisation it needs to maintain a kind of fixedness. Nevertheless, it still maintains its capacity to respond to stem cells.

"The ultimate goal is to provide a treatment for chronic disability after stroke, a condition for which there is no treatment at the moment. The only treatment at the moment is to protect the brain from further damage," he said.

In a process using a fine needle, about 10 million stem cells will be injected into the damaged area of each patient's brain in the hope that they will grow and differentiate into the specialist cells, and so return some function to that area of the brain.

Dr Sinden said that the foetal brain tissue is genetically manipulated in the test tube with a gene derived from a virus that infects monkeys.

At a temperature of 33C the gene causes the foetal stem cells to multiply continuously but it switches off at a temperature of 36C, two degrees below body temperature.

Dr Sinden said: "The gene has mutation in it which is a switch, which means that the gene is only active at a low temperature.

"So we can keep them growing indefinitely in the laboratory but as soon as we transfer them to an animal or human, the temperature is raised and cells with stop dividing." Dr Sinden said that although the patients will take drugs to suppress their immune systems and prevent tissue rejection, the problem should not be serious. "The brain is known to be an area of the body that is immune privileged, where tissue rejection is less of a problem," he said.

The chief purpose of the pilot trial will be to test the safety of the treatment. If it is successful, a larger trial involving more patients will follow.