Promise in stem cell research for Parkinson’s disease

Cell-replacement or stem cell therapy shows some promise as a treatment for Parkinson's. A recent paper in the journal Molecular & Cellular Proteomics reports a technical advance in selecting cells to use in this therapy.

Cell-replacement (stem cell) therapy involves differentiating stem cells into dopamine-signaling, or dopaminergic, neurons and transplanting them into a patient's brain to replace dying neurons. However, the variability of how the cells evolve (what specialty functions the cells learn) can affect transplantation outcomes. In clinical trials in the 1990s, for example, such contamination gave some patients severe dyskinesia, uncontrollable jerky movements that were worse than the movement problems caused by Parkinson's disease.

To avoid interference by unwanted cell types, researchers needed a differentiation protocol that yielded a more homogeneous (neutral/cleaner) population of dopaminergic neurons. Researchers led by Hossein Baharvand, of Iran's University of Science and Culture in Tehran, and Ghasem Hosseini Salekdeh, of the Academic Center for Education, Culture and Research in Iran and Macquarie University in Australia, set out to develop such a protocol.

First, the team developed a special stem cell line that contained a green fluorescent protein, or GFP, reporter for a transcription factor involved in dopaminergic neuronal development. In undifferentiated cells from this line, the fluorescent reporter is not expressed. When cells begin to make the transcription factor, the first step toward becoming a dopaminergic neuron, they begin to make the GFP protein. So essentially the scientists could take the undifferentiated cells and tell which ones would become good dopamine signaling cells over time by color of protein excreted as they changed. They then isolated those cells and transplanted them into rats modeling Parkinson's disease. Rats that received transplants with those cells had better dopamine release, indicating that the transplanted cells were a better match for the dying neurons they were meant to replace. Sorting the cells also reduced motor symptoms of Parkinson's compared with rats treated that received unsorted cells.

This is a major breakthrough in the idea of stem cell use for the treatment of Parkinson’s disease and shows promise for possible future use.