Dopamine-producing brain nerve cells, made from embryonic stem cells

Imagine a Parkinson’s treatment that works like a light switch, letting you turn it on or off when needed. Researchers at the University of Wisconsin–Madison have developed such an approach, and it could reshape treatment for many diseases.

For years, scientists have tried to replace the dopamine‑producing neurons destroyed by Parkinson’s. These cells control movement, and their loss leads to severe motor and emotional problems. Transplant attempts show mixed results. Some cells work. Many don’t make enough dopamine. About 10 percent make too much, causing graft‑induced dyskinesia.

UW–Madison researchers found a new way forward. Using CRISPR, they reprogrammed embryonic stem cells into two neuron types containing a genetic switch called a DREADD. When they gave mice a designer drug that activates DREADD, one cell type increased dopamine production while the other shut it down.

In a news release about the Cell Stem Cell,study, lead author Su‑Chun Zhang said this control is essential: “If we are going to use cell therapy, we need to know what the transplanted cell will do. If its activity is not right, we may want to activate it, or slow or stop it.”

Zhang said the system offers another advantage: “We can turn them on or off with a designer drug that acts only on cells with the designer receptor. The drug does not affect host cells. It’s a very clean system.”

Tests in mice showed the cells and drug worked as intended. Some cells boosted dopamine; others halted production.

It’s an encouraging start, but more work is needed to ensure safety and to deliver the drug and engineered cells to the right brain regions.

As Zhang notes, a reversible way to remotely control transplanted cells could transform treatment: “This is the first proof of principle using Parkinson’s as the model, but it may apply to many other diseases, not just neurological ones.”