Parkinson’s and stem cell therapy

Although the underlying cause of Parkinson’s is unknown, scientists do know that Parkinson’s results from the impairment and loss of dopamine producing cells in an area of the brain called the substantia nigra. It stands to reason therefore that replacement of those cells is a viable and potentially potent treatment method.

Cell-replacement therapy in Parkinson’s involves altering stem cells – special human cells that have the ability to develop into many different cell types – into dopamine producing nerve cells (or neurons) and then transplanting them into a person with Parkinson’s brain to replace the dying or lost neurons.

By the time a person is diagnosed with Parkinson’s, they have already lost approximately 50% of the dopamine-producing neurons from an area of the brain called the midbrain. The dopamine neurons are located in a part of the midbrain called the substantia nigra.

These neurons are critical for normal motor function in a person – without them, movement becomes very inhibited, resulting in the slowness and rigidity associated with Parkinson’s; and until we have developed methods that can identify Parkinson’s long before these nerve cells are lost and the motor features appear, some form of stem cell replacement therapy is required to introduce new cells to take up the lost function.

Stem cell transplantation represents the most straightforward (but still experimental) method of cell-replacement therapy.

Recent advances in this area of research have shifted away from the old approach of cell transplantation (using dopamine neurons from a donor embryo), to moving towards developing sophisticated methods for growing dopamine-producing neurons in cell culture.

It is important to understand that, by itself, cell transplantation is not curative and will not halt the progression of the condition. It is an experimental method of replacing lost nerve cells. There are however promising clinical trials happening now which are testing surgical transplantation of dopamine-producing nerve cells into people with Parkinson’s – the results of which will be available in the near future.