Progress towards stem cell treatment for Parkinson’s

Research studies carried out in Japan and the US are exploring the potential of using stem cells to replace cells that are lost in the brain during Parkinson’s.

What is a stem cell?

Every cell in the human body starts as a stem cell.  Stem cells have the potential to become many different types of cell in the body. Depending on where it is, a stem cell will receive signals that give it the instructions to become the cell that’s needed, for example a muscle cell, or a brain cell.

Stem cells are useful in Parkinson’s research because they can be used to generate brain cells to study in the lab. Taking stem cells from the skin of people with Parkinson’s and giving them the signals to become brain cells creates an ideal model for studying what might be happening in cells in the brain.

But researchers are also exploring whether stem cells could be used to replace brain cells that are lost in Parkinson’s. Over time, brain cells of people with Parkinson’s become damaged and start to die. These are important cells which produce a chemical called dopamine. As the cells die, levels of dopamine fall, and this leads to many of the symptoms associated with Parkinson’s. Crucially, these cells are not naturally replaced. Although there are treatments that can treat the symptoms of Parkinson’s, there’s currently nothing that can slow or stop the loss of these cells.

Read more about ongoing research using stem cells in our research blog.

What does the latest research show?

The 2 studies that have shared their results used human stem cells that had been reprogrammed to become cells that produce the brain chemical dopamine. Participants in the study had surgery to inject the new cells into an area of the brain, and have been monitored closely.

The aims of both studies were to explore the safety of the stem cell surgery, and to check for any side effects. 

The first study involved 7 people with Parkinson’s in Japan, aged between 50 and 69. Everyone involved in the study was followed for 2 years. During this time, there was no report of any unwanted side effects, and scans showed that the injected cells were able to produce dopamine.

Find the full results on the Nature journal website.

The second study followed 12 people with Parkinson’s in the US. The researchers split the participants into 2 groups to test how many cells would be the optimal number to inject during the surgery without risking side effects. None of the participants experienced any severe side effects as a result of the treatment, regardless of whether they had received a low or a high dose of cells.

Read the full results of this study on the Nature journal website.

Some participants in both studies also reported that they had fewer movement symptoms after having the surgery. However, this varied among participants and would need further research and follow up to understand more clearly.

What happens next?

Claire Bale, Associate Director of Research, said: "Stem cell therapies hold huge promise for slowing, or even reversing, the progression of Parkinson’s as they could be used to replace lost brain cells to potentially restore lost function.

"However, making stem cell therapies a reality has proven challenging. From a practical perspective, growing sufficient quantities of the right kind of cells to transplant, and from a safety perspective, making sure that transplanted cells don't cause side effects like dyskinesia, or worse, form tumours.

"It's really encouraging to see these findings from 2 separate early-stage trials. The results show that stem cell therapies can be delivered safely to people with Parkinson's, and also offer hope that the transplanted cells are starting to produce improvements in symptoms.

"There is still a lot more research to do but these studies are an important step forwards for stem cell therapies in Parkinson's."