December 21, 2007 by mike.

Parkinson disease (PD) is caused by the progressive degeneration of brain cells known as dopamine (DA) cells.
Replacing these cells is considered a promising therapeutic strategy. Although DA cell-replacement therapy by transplantation of human fetal mesencephalic tissue has shown promise in clinical trials, limited tissue availability means that other sources of these cells are needed. Now, Ernest Arenas and colleagues at the Karolinska Institue, Sweden, have identified a new source for DA cells that provided marked benefit when transplanted into mice with a PD-like disease.

In the study, DA cells were derived from ventral midbrain (VM) neural stem cells/progenitors by culturing them in the presence of a number of factors - FGF2, sonic hedgehog, and FGF8 - and engineering them to express Wnt5a. This protocol generated 10-fold more DA cells than did conventional FGF2 treatment. Further analysis revealed that these cells initiated substantial cellular and functional recovery when transplanted into mice with PD-like disease. Importantly, the mice did not develop tumors, a potential risk that has precluded the clinical development of embryonic stem cells as a source of DA cells. These data led the authors to suggest that Wnt5a-treated neural stem cells might be an efficient and safe source of DA cells for the treatment of individuals with PD.

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December 21, 2007 by mike.

The authors investigated the effects of green tea polyphenols, a group of naturally occurring chemical substances found in plants that have antioxidant properties, in an animal model of Parkinson’s disease.

Parkinson’s disease is a progressive, degenerative disorder of the central nervous system, resulting from the loss of dopamine-producing brain cells, and there is presently no cure. According to Dr. Baolu Zhao, corresponding and senior author on this article, current treatments for Parkinson’s are associated with serious and important side effects. Their previous research has indicated that green tea possesses neuroprotective effects, leading Guo and colleagues to examine its effects specifically in Parkinson’s. The authors discovered that green tea polyphenols protect dopamine neurons that increases with the amount consumed. They also show that this protective effect is mediated by inhibition of the ROS-NO pathway, a pathway that may contribute to cell death in Parkinson’s.

Considering the popularity of green tea beverages worldwide, there is enormous public interest in the health effects of its consumption. John H. Krystal, M.D., Editor of Biological Psychiatry and affiliated with both Yale University School of Medicine and the VA Connecticut Healthcare System, reminds us that “many health-related claims have been made for a wide variety of naturally-occurring substances and many of these claims, as in the case of St. John’s Wort and Ginko Biloba, have not held up in rigorous clinical studies. Thus, it is extremely important to identify the putative neuroprotective mechanisms in animal models, as Guo and colleagues have begun to do for Parkinson’s disease.”

Dr. Zhao’s hope is that eventually “green tea polyphenols may be developed into a safe and easily administrable drug for Parkinson’s disease.” Dr. Krystal agrees, that “if green tea consumption can be shown to have meaningful neuroprotective actions in patients, this would be an extremely important advance.”

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