Can we encourage the brain to protect itself in Parkinson’s?

What are growth factors?

Growth factors are a family of extraordinary proteins that play a range of important roles in our bodies, from the development of our brains during childhood to promoting the ability of our brains to change and adapt during adulthood. They are essential during development to ensure that our nervous systems are wired up properly and, during adulthood, they continue to be important in the maintenance and regeneration of damaged cells.

These properties have made them a target for the development of new treatments for Parkinson’s. If we can boost the levels of some of these growth factors in the brain areas that are affected in the condition, perhaps they could protect brain cells or maybe even help to repair the damage done to them.

Sounds promising? But, growth factors are large proteins that can’t naturally cross the blood-brain barrier, so getting them into the areas of the brain where they are needed is a challenge. Most research to date has relied on invasive and expensive surgery.

Research so far

Probably the most famous growth factor investigated in relation to Parkinson’s is GDNF (glial cell line-derived neurotrophic factor), which was recently featured in a BBC documentary. This particular growth factor was tested in a groundbreaking clinical trial in which 41 people with Parkinson’s underwent a pioneering surgery, designed to precisely deliver the growth factor to the region of the brain affected in the condition.

Although the results were complex, there was evidence that GDNF was able to increase dopamine levels in specific regions of the brain. This offers real hope that it may be possible to reawaken and restore damaged brain cells in Parkinson’s. But in order to prove that GDNF is an effective treatment, more research is needed. Read more about the results of the GDNF trial.

But, even if the infusion of growth factors, such as GDNF, are shown to be beneficial and approved as a treatment for Parkinson’s, this highly invasive procedure may not be practical for the NHS and appropriate for all. Is there an alternative or another way?

Let’s introduce FGF20 (fibroblast growth factor 20).

Like GDNF, FGF20 has been shown in the lab to protect and promote the growth and survival of dopamine-producing cells. And previous studies in rats have shown that direct infusion, via surgical methods, of FGF20 into the brain can protect brain cells from damage.

Dr Susan Duty is particularly interested in the effects of FGF20, and seeing whether it’s possible to boost its levels in the brain without the need for invasive surgery.

Existing drugs to boost the brain’s supply of FGF20

In research previously funded by Parkinson’s UK, Dr Susan Duty and her team looked at whether existing drugs could boost FGF20 in the brains of rat models of Parkinson’s. They took a list of 1,261 approved drugs and whittled this list down to 4 based on whether the drugs could cross the blood-brain barrier and on their FGF20 boosting abilities. These 4 were taken forward to test in the rat model of Parkinson’s. 

2 of these drugs proved the most effective: salbutamol, an anti-asthmatic medication, and triflusal, an aspirin-like drug, were both seen to increase FGF20 levels in the rat brains. The full scientific paper can be read on the Springer Nature website.

Salbutamol has been shown in other research to have a protective effect on brain cells and its role in boosting FGF20 could help explain this.

This research is now moving forward:

Parkinson’s UK is funding the next stage of the study, where the researchers will further investigate the potential of these drugs for treating Parkinson’s, particularly looking at whether the drugs can protect brain cells in a rat model of the condition. If they can, it’s a promising sign that boosting FGF20 levels could be an effective treatment for Parkinson’s.

Although this research is still being investigated in the lab, using re-purposed drugs that have already been developed and tested in people, may mean the potential treatment can become available more quickly, easily and cheaply.

Professor Susan Duty, Professor in Pharmacology and Neuroscience at King's College London, said:

"Using existing medicines, ones already known to be safe for use in people, might help cut down the time between our current studies and any potential future clinical trial.

"If we can demonstrate in follow-up studies that salbutamol or triflusal can promote survival of dopamine-containing cells in the brain, we will be another step closer to clinical trials to see whether these medicines are effective in people with Parkinson’s."