Researchers from Kyoto University in Japan started a clinical trial this month to treat Parkinson’s disease with reprogrammed stem cells. This follows the successful restoration of brain cell function in monkeys using these stem cells reported last year.
Parkinson’s disease is characterized by the loss of a specific type of neuron in the brain, called dopaminergic neurons, which make the essential neurotransmitter dopamine. The reduced dopamine levels lead to motor skill decline, causing the characteristic trembling and difficulty walking. Currently, there is no cure for Parkinson’s disease. Therapies to help relieve symptoms include lifestyle changes (diet, exercise, physical therapy), taking a drug to increase dopamine levels in the brain, and deep brain stimulation surgery to electrically inactivate the brain portions responsible for motor symptoms.
However, adding neural progenitor cells, which are derived from reprogrammed stem cells, back into the patients’ brains might replace the lost neurons and cure the disease. In monkey brains, the neural progenitor cells differentiated into dopaminergic neurons and survived for up to two years. Motor symptoms associated with Parkinson’s disease also improved after treating the monkeys.
To make the replacement dopaminergic neurons, mature adult cells (usually from the skin or blood) were treated to revert back to being stem cells, called induced pluripotent stem cells (iPSCs). At this point, the iPSCs can be reprogrammed to become many types of cells. In this case, they were turned into dopaminergic neural progenitor cells, which specifically develop into dopaminergic neurons. Using iPSCs rather than stem cells from human embryos means this treatment would be potentially available in countries that ban the use of embryonic stem cells, such as Ireland, Italy, and most African and South American countries.
Patient recruitment for this trial began this month. Seven patients will be recruited, treated with neural progenitor cells via direct injection into the brain, and studied for 2 years post-injection. Because there is a chance the immune system would react adversely to the injected cells, patients will be given a common immunosuppressant drug (Tacrolimus) during cell injection. Although the procedure in this trial requires brain surgery, it will hopefully be a long-term, effective solution.
Managing Correspondent: Chelsea Weidman Burke
Press Article: Trial Launched to Treat Parkinson’s with Reprogrammed Stem Cells. The Scientist.
Press Release: Doctor-Driven Clinical Trial on Parkinson’s Disease Treatment Using iPS Cell Derived Dopamine Neural Progenitor Cells. Kyoto University.
Original Journal Article: Human iPS cell-derived dopaminergic neurons function in a primate Parkinson’s disease model. Nature.
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