• A new study shows that scientists are a step closer to developing a better treatment option for Parkinson’s disease.
  • Scientists have found the optimal stage to replace damaged brain cells with healthy ones derived from stem cells.
  • Identifying the most suitable cells at an appropriate stage leads to a more effective transplantation process.

Scientists are now a step closer to developing a better treatment option for Parkinson’s disease, according to a new study. This is in the area of replacing damaged brain cells with healthy ones derived from human embryonic stem cells so patients can regain their physical functions and movement.

In the new study, what was determined is the optimal stage when the stem cells should be transplanted to get the best results. The study is co-led by the National Neuroscience Institute, Singapore and Agency for Science, Technology and Research (A*STAR).

Parkinson’s disease is a progressive degeneration of the nervous system. It is the second most common neurodegenerative disease in Singapore, after Alzheimer’s disease. It affects three in every 1,000 people aged over 50. Symptoms of the disease include tremors in the arms or legs when at rest and movement loss.

Parkinson’s disease is characterised by the loss of dopaminergic (DA) neurons – cells in the midbrain that help regulate movement and emotional responses. While medication may slow or improve Parkinson’s symptoms, there is currently no cure.

However, one promising potential therapy that has emerged in recent years is cell replacement therapy designed to restore the DA neurons. For the study, the team focused on three stages of DA cells that were going through differentiation – a process whereby embryonic stem cells develop into different types of cells with specialised functions. After that, the cells will be transplanted into mice models with Parkinson’s disease.

"Yet no systematic comparison analysis has been conducted to identify which differentiation stages of the DA cells are most suitable for this. It is essential that we determine this before proceeding to clinical trials in human patients," said Professor Tan Eng King, Research Director at the National Neuroscience Institute and a co-leader of the study.

The research is funded by the National Medical Research Council-Translational and Clinical Research (NMRC-TCR) Flagship Programme, under which Professor Tan is the lead investigator for the Translational Clinical Research Programme in Parkinson’s Disease.

"We identified immature DA neurons, differentiated for 25 days as the most suitable cell source for future Parkinson’s disease cell therapy. Cell types at earlier or later stages of differentiation were not suitable due to their immaturity and reduced ability to survive in vivo," said co-lead investigator Dr Steve Oh, Director of Stem Cell Bioprocessing, Bioprocessing Technology Institute, Agency for Science, Technology and Research (A*STAR).

Said Dr Zeng Li, a Senior Research Scientist at the National Neuroscience Institute: "Our findings show the importance of identifying the most suitable cells at an appropriate differentiation stage for achieving safe and efficacious DA neuron engraftment. It also provides valuable guidelines for standardising the differentiation stage of the transplantable cells used in treating Parkinson’s disease."

"The next step is to conduct studies to develop a more scalable production method tailored for this DA cell population to ensure consistency, efficacy and safety of the therapy."

This study was recently published by STEM CELLS Translational Medicine. The publication has also issued a press release to US media about this study. The full article, "Immature midbrain dopaminergic neurons derived from floor-plate method improve cell transplantation therapy efficacy for Parkinson’s disease," can be accessed at: http://onlinelibrary.wiley.com/doi/10.1002/sctm.16-0470/full.