New Gene Therapies May Slow Parkinson's Disease

Two gene therapies for Parkinson's disease are showing promise at preventing the disease's progression and avoiding side-effects of existing treatments.

The therapies are being studied by an international team from Lund University in Sweden, the University of Cambridge in the UK and the University of Florida

One of the treatment approaches is aimed at halting Parkinson's disease at its onset while the other is aimed at avoiding side-effects that occur when treating the disease in its later stages.

Preventing damage

In a study of the first approach, researchers inserted corrective genes into the brain of small monkeys called marmosets.

The genes helped to prevent brain damage by producing therapeutic levels of a protein called glial cell line-derived neurotrophic factor (GDNF).

GDNF helps nourish brain cells and has attracted attention for treating Parkinson's disease.

Its use has been debated, however, since human trials ended last year after trial-conductor Amgen cited safety concerns. Many people with Parkinson's still want the treatment.

The gene therapy approach appears to produce more manageable levels of the protein in the brain.

In tests with 31 monkeys, GDNF genes inserted into a region in the front part of the brain called the striatum protected monkeys when drugs were used to induce Parkinson's-like conditions by destroying dopamine-producing cells.

Seventeen weeks after receiving the drug, GDNF-treated monkeys showed improvement in performing tasks and analysis of brain tissue showed the animals' dopamine systems were spared.

Reversing abnormal movement

In the second approach, researchers used gene therapy to reverse abnormal movements called dyskinesias in some rats.

The approach could combat flailing movements produced by Levodopa, a widely used drug treatment for Parkinson's disease.

While Levodopa usually works well for several years, it can eventually start causing movement problems.

It is hoped that gene therapy could prevent harmful fluctuations of L-dopa, a precursor of dopamine.

In 33 rats with severe dopamine depletion who had limited use of their left paw, gene therapy to provide a source of L-dopa caused complete recovery of movement.

The studies are reported in the journal Brain and The Journal of Neuroscience.