The researchers said the work showed there were both benefits and risks of using human embryonic stem cells for treatment. Human stem cells have been highly touted for their ability to replace diseased tissue; however, the use of these same stem cells is controversial because human embryos have to be destroyed to obtain them.
"The behavioral data validate the utility of the approach. But it also raises a cautionary flag and says we are not ready for prime time yet," said lead stem cell researcher Steven A. Goldman, a professor of neurology and neurosurgery at the University of Rochester Medical Center.
Goldman went on to say that with modest changes in stem cell deployment techniques, researchers would be able to keep the benefits of the treatment while reducing -- or even eliminating -- the chances of stem cell recipients producing cancer-like growths as a result of treatment.
Goldman's team treated laboratory-cultured human embryonic stem cells in a new way that induced many to become a kind of neuron that produces dopamine, a neurotransmitter. Those kinds of neurons are gradually lost in Parkinson's disease, resulting in the body being deprived of the essential chemical messenger. Parkinson's disease patients commonly suffer from motor control problems like trembling and muscle rigidity.
Geron is a California company that hopes to gain Food and Drug Administration permission to treat spinal-cord-injury patients with modified embryonic stem cells next year. Geron's president -- Thomas Okarma -- said his company's stem cells have shown no sign of causing tumor growth in any of its animal studies. Okarma added that the FDA has asked for additional extensive data on that particular problem before it will give its final approval for any further research that may result in a possible Geron product.
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