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ďArtificialĒ Stem Cells May Help Reveal Parkinsonís Disease Causes, Treatments
- Jul 20 2012
Scientists have long recognized the potential of stem cells to increase our understanding of Parkinson’s disease (PD) and develop new treatments. Now, in a study published in the July 4, 2012 issue of Science Translational Medicine, researchers report that they have taken a major step toward realizing this potential by generating stem cells from five people living with inherited forms of Parkinson’s. They then changed these stem cells into brain cells to study cellular problems associated with PD and to explore ways to fix them.
Stem cells are non-specialized cells that have the ability to become any type of cell in the body, including skin, brain, or muscle cells. Induced pluripotent stem cells (iPSCs) are “artificial” stem cells that scientists make in the lab by taking cells from adults (often from the skin) and treating them to remove their “specialized” function. Once the skin cells are turned into iPSCs or stem cells, researchers can then manipulate them into other, more specialized cell types they might want to study—for example, the dopamine neurons lost as Parkinson’s disease progresses.
The iPSCs from the skin cells of five people with inherited forms of Parkinson’s disease were generated by a large, multi-institutional research team that included several PDF-supported scientists. It was led by Ole Isacson, M.D., at Harvard Medical School and funded by the National Institute of Neurological Disorders and Stroke through the American Recovery and Reinvestment Act. These people had mutations in PINK1 or LRRK2, two genes that scientists have linked to inherited PD. The researchers then grew the iPSCs into dopamine neurons, the cell type affected by PD. They then compared these neurons with other similarly iPSC-derived neurons created from two people without PD. They focused their studies on differences in the functioning of mitochondria, tiny energy-producing structures in cells, between healthy people and those with PD.
- iPSC-derived neurons from people with PINK1 or LRRK2 genetic forms of PD were more vulnerable to several toxic chemicals, like hydrogen peroxide, than were neurons from healthy people.
- Neurons from people with the PINK1 or LRRK2 genetic forms of PD also showed impaired mitochondrial functioning and energy production compared with neurons from healthy people.
- The researchers found that they could “rescue” PD neurons from mitochondrial problems by treating the cells with various chemicals, such as the antioxidant coenzyme Q10 or an inhibitor of the enzyme encoded by the LRRK2 gene. The different genetic forms of PD showed different responses to the treatments.
What Does It Mean?
In spite of much progress, scientists do not know what causes Parkinson’s in most people living with it. Even among the minority of people with PD who carry known genetic mutations, scientists do not know how these mutations cause PD. By studying iPSC cells from people with genetic mutations linked to PD, Dr. Isacson and his colleagues tried to better understand the cellular mechanism for PD, at least in this small population.
Neurons from people with PD with mutations in the PINK1 and LRRK2 genes were both more vulnerable to chemical exposure than neurons derived from healthy people. This increased sensitivity may arise from problems in mitochondria, which cause a shortage of energy in the cell. Previous studies have already linked PD to mitochondrial dysfunction. However, this study is unique because it provides evidence that mitochondrial defects in human neurons also underlie multiple genetic forms of PD.
iPSC technology allowed the researchers to change skin cells from individuals with PD into neurons, the cell type affected by PD. Unlike brain cells, skin cells can be quickly and easily obtained from people. This strategy could someday be used to study cell defects in people with PD and tailor a therapy uniquely suited to their own cells. Indeed, Dr. Isacson’s study suggests that different forms of PD may respond differently to various treatments. First, however, the researchers need to generate iPSCs from a larger group of people, including those with sporadic Parkinson's (meaning, the more common form of PD that is not caused by genetics), to confirm these results.
Reference: Pharmacological Rescue of Mitochondrial Deficits in iPSC-Derived Neural Cells from Patients with Familial Parkinson’s Disease, Oliver Cooper, Hyemyung Seo, Shaida Andrabi, Cristina Guardia-Laguarta, John Graziotto, Maria Sundberg, Jesse R. McLean, Luis Carrillo-Reid, Zhong Xie, Teresia Osborn, Gunnar Hargus, Michela Deleidi, Tristan Lawson, Helle Bogetofte, Eduardo Perez-Torres, Lorraine Clark, Carol Moskowitz, Joseph Mazzulli, Li Chen, Laura Volpicelli-Daley, Norma Romero, Houbo Jiang, Ryan J. Uitti, Zhigao Huang, Grzegorz Opala, Leslie A. Scarffe, Valina L. Dawson, Christine Klein, Jian Feng, Owen A. Ross, John Q. Trojanowski, Virginia M.-Y. Lee, Karen Marder, D. James Surmeier, Zbigniew K. Wszolek, Serge Przedborski, Dimitri Krainc, Ted M. Dawson, and Ole Isacson; Sci Transl Med 4 July 2012 4:141ra90. [DOI:10.1126/scitranslmed.3003985]
Source Date: Jul 20 2012