The first trial to test the effect of a growth-factor compound in humans with Parkinson’s disease has shown promising results. A report in the Journal of Clinical Investigation raises the hope that one day we will see regenerative treatments for Parkinson’s disease that use the brain’s own protective mechanisms to halt the loss of brain cells and restore dopamine levels.

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PET scans show dopamine signaling activity before and after treatment – white areas signify more intense activity.
Image credit: Lund University

There are millions of people worldwide living with Parkinson’s disease – a progressive movement disorder that results from the loss of brain cells that produce the chemical dopamine.

The symptoms of Parkinson’s – which include tremor, stiffness, slowness and impaired balance – gradually worsen and patients experience increasing difficulty walking, talking and taking care of themselves.

Research into the effects of platelet-derived growth factor or PDGF started over 10 years ago with studies in animals. These found that the growth factor reduces symptoms of Parkinson’s, improves motor skills, and restores levels of dopamine in the brain. They also suggest PDGF repairs neurons and nerve fibers.

In their double-blind, randomized, placebo-controlled trial – the first in human patients – researchers at Lund University and Karolinska Institutet in Sweden tested the safety and tolerability of PDGF in 12 patients with Parkinson’s disease.

Fast facts about Parkinson’s disease
  • Parkinson’s disease arises through loss of dopamine-producing brain cells
  • It usually affects people over the age of 60
  • At present there is no cure, but there are drugs that provide dramatic relief from the symptoms.

Find out more about Parkinson’s disease

The treatment – PDGF or placebo – was delivered via a pump surgically implanted in the abdomen, with an internal catheter that went up into the brain. The pump delivered the drug for 12 days, and patients were followed for another 73 days, during which the pump delivered an infusion of saline.

The results show that PDGF does not cause serious, unresolvable side effects. The researchers were also encouraged by other results, which they discovered when they examined PET scans of the patients’ brains taken 4 months after treatment.

The PET scan images showed that in the patients who received the active treatment – as opposed to placebo – levels of dopamine signaling were not only maintained, but even increased.

First author Gesine Paul, research group leader and Associate Professor at Lund University, explains that in Parkinson’s disease, the brain is continuously losing nerve cells, causing a gradual decline in dopamine levels. But:

“What we have seen is that the patients who received the highest dose did not have the same decrease in these signals as the placebo-treated patients. Instead, we have actually seen an increase in signaling here.”

The team is very excited about the results because they indicate PDGF can restore structures in the brain that are lost in Parkinson’s disease – something current treatments can’t do. Prof. Paul notes:

Although we still have a long way to go our study suggests that it may be possible to stimulate the brain’s built-in protective mechanisms in order to slow or halt disease progression.”

The team says clinical trials in larger groups of patients are now needed and they hope that journey will be shorter than the one that has brought them to this point. They anticipate these larger trials will take place in Sweden, Germany and England.

They also want to examine and understand the detailed mechanisms responsible for the repair and regeneration that PDGF seems to trigger in the brain.

The trial was carried out in collaboration with the Swedish biotech company Newron Sweden who will continue to partner the team in future trials. Funding came from Vinnova and the European Commission.

Meanwhile, Medical News Today has learned that difficult-to-treat symptoms of Parkinson’s appear to respond to low- frequency deep brain stimulation. A study published recently in the journal Neurology shows that patients with swallowing dysfunction and freezing of gait experienced more significant improvement after low-frequency treatment compared with the more usual high-frequency deep brain stimulation.