7/11/2011: BRAIN CELLS that die off in Parkinson’s disease have been grown from stem cells and grafted into monkeys’ brains in a big step towards new treatment. US researchers say they have overcome previous difficulties in coaxing human embryonic stem cells to become the neurons killed by the disease. Tests showed the cells survive and function normally in animals and reverse movement problems caused by Parkinson’s in monkeys. The breakthrough raises the prospect of transplanting freshly grown dopamine-producing cells into human patients to treat the disease.

“Previously we did not fully understand the particular signals needed to tell stem cells how to differentiate into the right type of cells,” said Dr Lorenz Studer at the Memorial Sloan-Kettering Cancer Centre in New York. “The cells produced in the past would produce some dopamine but were not quite the right type of cell, so there were limited improvements in the animals. Now we know how to do it right, which is promising for future clinical use.”

Parkinson’s disease takes hold as cells that produce the chemical dopamine die off in a part of the brain called the substantia nigra. This causes tremors, rigidity and slowness of movement, though patients may also experience tiredness, pain, depression and constipation, which worsen as the disease progresses.

The main treatments for Parkinson’s are drugs that aim to control the symptoms by increasing the levels of dopamine that reach the brain and stimulating the parts of the brain where dopamine works.

Some patients have wires surgically implanted into their brains that deliver electrical pulses to alleviate movement problems.

Experiments in which dopamine neurons were created from mouse stem cells have not been successfully reproduced in humans. There have also been safety concerns, with signs that dopamine neurons developed from human stem cells can trigger the growth of tumours.

Dr Studer and his colleagues, whose work is published in the journal Nature, found the specific chemical signals required to nudge stem cells into the right kind of dopamine-producing brain cells.

The team gave animals six injections of more than a million cells each, to parts of the brain affected by Parkinson’s. The neurons survived, formed new connections and restored lost movement in mouse, rat and monkey models of the disease, with no sign of tumour development. The improvement in monkeys was crucial, as the rodent brains required fewer working neurons to overcome their symptoms. – ( Guardian service)


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To visit The Parkinsons Association of Ireland visit http://www.parkinsons.ie/