The breakthrough now brings promise to the concept of transplanting freshly grown dopamine-producing cells into human patients to treat the disease.
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.
Parkinson’s disease establishes itself as cells that produce dopamine are killed off in a section of the brain called the substantia nigra. The result are tremors, rigidity and slowness of movement, though patients may also experience pain, tiredness, depression and constipation, which worsens during the disease’s progression.
Current treatments for Parkinson’s include drugs that target the symptoms by increasing dopamine levels in the brain and stimulating the areas where dopamine works. Some patients have wires surgically implanted into their brains that deliver electrical pulses to alleviate movement problems.
Dr. Lorenz Studer of the Sloan Memorial Sloan-Kettering Cancer Center and his colleagues have found the specific chemical signals necessary to push stem cells into becoming the right kind of dopamine-producing brain cells.
In a series of experiments, the team provided animals with six injections of more than a million cells each, to areas of the brain affected by Parkinson’s. The neurons survived, created new connections and restored lost movement in mouse, rat, and monkey models of the disease, with no sign of tumor growth. The improvement in the monkey models was critical, since rodent brains required fewer working neurons to overcome their symptoms.
On the prospect of future human trials, Dr Studer claimed, "We now have the right cells, but to put them into humans requires them to be produced in a specialized facility rather than a laboratory, for safety reasons. We have removed the main biological bottleneck and now it's an engineering problem."