Stem cells repair damaged circuits in mice with Parkinson’s
Written by James Kingsland on September 30, 2020 — Fact checked by Alexandra Sanfins, Ph.D.
A study suggests a type of nerve cell derived from stem cells can make the right connections when implanted into the brain, restoring lost motor function.
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Parkinson’s disease is a progressive degenerative disorder that affects muscular control.
Its symptoms include tremor, rigidity, slowness of movement, and impaired balance. Difficulties with swallowing and speaking are also common, particularly later in the course of the disease.
The National Institutes of Health estimate that about 50,000 people are diagnosed with Parkinson’s every year in the United States, and around half a million people live with the condition.
In the disease’s early stages, before symptoms appear, certain brain cells called the “substantia nigra” start to die. These cells produce dopamine, a nerve signaling molecule, or neurotransmitter, which is essential for the smooth movement of muscles.
There is currently no cure for Parkinson’s, but one promising line of research involves transplanting nerve cells into the brain to replace lost functions. Experts could potentially use the same approach to repair damage caused by other neurodegenerative disorders and trauma.
However, for such therapies to succeed, the transplanted nerve cells must make the right connections.
“Our brain is wired in such an accurate way by specialized nerve cells in particular locations so we can engage in all our complex behaviors. This all depends on circuits that are wired by specific cell types,” says Su-Chun Zhang, a professor of neuroscience and neurology at the Waisman Center in the University of Wisconsin-Madison.
“Neurological injuries usually affect specific brain regions or specific cell types, disrupting circuits,” he says. “To treat those diseases, we have to restore these circuits.”
To repair the lost neural circuitry, implanted cells would need to send out projections or “axons” to transmit signals to the correct targets in distant regions of the brain. They would also need to receive the appropriate signals from other nerve cells.
One major unanswered question is whether it is the exact location in the brain where the cells are implanted or the identity of the cells themselves that determine these connections.
It is also unknown whether such new connections would restore lost brain functions.
Zhang and his colleagues set out to find the answers through experiments on mice with Parkinson’s.
They report their results in the journal Cell Stem Cell.