Parkinson’s disease is a progressive neurodegenerative disorder. Although its symptoms can be managed with medications, currently it has no cure and invariably progresses over time. However, this may change as stem cell therapy is increasingly being viewed as a possible cure.

The theory

The idea of using stem cell therapy to treat Parkinson’s disease is not new. The first experiments were conducted almost 30 years ago, when fetal stem cells were injected into the brains of a few volunteers. Unfortunately, many of the volunteers simply rejected the foreign stem cells. The volunteers who didn’t reject the stem cells often went on to develop an unpleasant movement disorder called dyskinesia.Since then, many advances in stem cell research have been made, and currently doctors know how to obtain stem cells from individual patients, totally bypassing the problem of rejection. Scientists have been able to derive stem cells from the patient’s own skin or blood, culture them in vitro, and then trigger them to differentiate into dopamine-producing neurons.

Current treatments for Parkinson’s disease revolve around taking medications that provide extra dopamine to the brain. However, these medications can have unpleasant side effects and do nothing to halt the deterioration and death of additional neurons.

The idea behind stem cell therapy for Parkinson’s is to replace the dead and dying dopamine-producing neurons with healthy, new dopamine-producing neurons. In theory, in one or two fairly minor surgical procedures, the patient could have a supply of these new neurons implanted into their brain, thus providing a cure for the condition.

The research

Researchers have managed to cure Parkinson’s disease in animal models of the disease by implanting stem cells into their brains. However, just because something works to treat an artificial disease model in a rodent doesn’t mean it will work for sure in humans.In the fall of 2018, in Japan, doctors implanted 2.4 million prepared stem cells into 12 places in the brain of a 50-year-old man with Parkinson’s disease who volunteered for the procedure. He did well and six months later underwent a second introduction of an additional dose of stem cells. After observing his progress for two years and confirming the treatment is safe, an additional six patients will be given the treatment at the end of 2020.

If these patients’ results are as good as expected, Japan will almost certainly approve the therapy for general use by or before 2023, paving the way for worldwide treatment of all patients with Parkinson’s disease.