Neural Stem Cells Reduce Symptoms of Parkinson’s Disease in Animal Studies

Implanting stem cells derived from unfertilized human eggs appears safe, effective in animal models

The transplantation of neural stem cells derived from unfertilized human eggs into the brains of animal models of Parkinson’s disease has been shown to preserve dopamine levels and cells and reduce disease symptoms six months after cell transplantation, according to findings presented November 18 at Neuroscience 2014, the annual meeting of the Society for Neuroscience and the world’s largest source of emerging news about brain science and health.

“Cell - based therapies hold great promise in the treatment of Parkinson’s disease, for which there is currently no cure,” said lead author Ruslan Semechkin of the International Stem Cell Corp. in Carlsbad, California. “We believe these human neural stem cells provide a valuable new approach, and the results presented here bring the development of a disease - modifying treatment for Parkinson’s a step closer to reality.”

An estimated 7 million to 10 million people worldwide are living with Parkinson’s disease, marked by symptoms including tremors, muscular rigidity, and slow, imprecise movement. Parkinson’s lowers levels of the neurotransmitter dopamine and causes the degeneration of a group of structures at the base of the brain involved with the coordination of movement. Current treatments manage the symptoms, but they do not stop disease progression and many produce unwanted side effects.

The researchers reported results from three preclinical studies evaluating the safety and efficacy of implanting neural stem cells derived from unfertilized human eggs in both nonhuman primates and rodents. Neural stem cells have the ability to differentiate into all the neural cells (neurons, astrocytes, and oligodendrocytes) that constitute the nervous system. The researchers worked with a type of stem cell s called human parthenogenetic neural stem cells, which, unlike embryonic stem cells, do not require the destruction of embryos. These cells can be expanded indefinitely in the laboratory, providing the large cell numbers needed to treat Parkinson’s patients.

Results from one of the nonhuman primate studies showed that six months after cell transplantation , Parkinson ’s symptoms were reduced and many healthy behaviors had returned to close to normal levels. Rodent studies indicate d that the stem cells are safe, even at very high doses, with no signs of abnormal tissue, tumors, or stem cells spreading to other parts of the animal. In addition to behavioral improvements, higher levels of dopamine were detected in the treatment groups when compared with the control groups that did not receive transplanted cells.

These results will form part of an Investigational New Drug Application with the Food and Drug Administration supporting the use of these cells for the treatment of Parkinson’s disease.

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Society for Neuroscience press release