Stem cell treatment for Parkinson's to be assessed in the clinic

An early phase clinical trial using induced pluripotent stem cells (iPSCs) to treat Parkinson's disease has been approved.

Parkinson's disease is a neurodegenerative movement disorder characterised by a resting tremor, slowed movement and stiffness. It results from degeneration of dopamine-producing neurons in the basal ganglia, which reduces dopamine levels and causes motor symptoms. Current medications relieve symptoms, but do not provide a cure. A phase I clinical trial, conducted by Keck Medicine of the University of Southern California, is investigating whether specialised stem cells implanted in the brain can restore dopamine production and potentially slow or reverse the disease.

Dr Brian Lee, a neurosurgeon at Keck Medicine and principal investigator of this study said, 'If the brain can once again produce normal levels of dopamine, Parkinson's disease may be slowed down and motor function restored.'

In this trial, the team will treat 12 people with moderate to moderate-severe Parkinson's disease using iPSCs. These cells are generated by reprogramming a patient's own cells so that they can differentiate into any cell type. A small hole will be made in the skull and the iPSCs will be implanted into the basal ganglia. The researchers hopes that this environment will encourage the iPSCs to differentiate into dopamine-producing neurons, providing a long-term improvement in motor symptoms. Patients will be monitored for 12-15 months for changes in symptoms and potential side effects, with follow-up planned for five years.

Dr Xenos Mason, a neurologist at Keck Medicine and co-principal investigator, said, 'We believe that these iPSCs can reliably mature into dopamine-producing brain cells, and offer the best chance of jump-starting the brain's dopamine production.'

Previous stem cell trials for Parkinson's disease (see BioNews 1258 and 1309) mostly relied on embryonic stem cells (ESCs), reprogrammed into dopaminergic neurons. However, ESCs are obtained from embryos and are genetically different from the patient, creating a risk of immune rejection. In contrast, iPSCs are created from a patient's own cells, avoiding this problem while also avoiding the ethical concerns associated with using embryos.

This trial is being carried out across three different sites in the USA. This trial has also been granted fast-track designation by the US Food and Drug Association, allowing accelerated evaluation of safety and efficacy. As Dr Lee concluded, 'Our ultimate goal is to pioneer a technique that can repair patients' motor function and offer them a better quality of life.'