The condition is closely linked to a drop in dopamine levels in the brain. Dopamine is a chemical messenger that plays a critical role in controlling movement, as well as supporting memory, mood, and other essential functions. As dopamine producing brain cells progressively die off, the brain loses its ability to properly regulate movement. This breakdown leads to the hallmark symptoms of Parkinson’s, including tremors, muscle stiffness, and slowed motion.

Researchers at Keck Medicine of USC are now testing a new approach that aims to address this dopamine loss directly. In an early phase clinical trial, doctors are implanting specially engineered stem cells into the brain. These cells are designed to replace damaged neurons and generate dopamine.

“If the brain can once again produce normal levels of dopamine, Parkinson’s disease may be slowed down and motor function restored,” said Brian Lee, MD, PhD, a neurosurgeon with Keck Medicine and principal investigator of the study.

Reprogrammed Stem Cells Designed to Produce Dopamine

The treatment uses a newer type of lab created stem cell known as induced pluripotent stem cells (iPSCs). Unlike embryonic stem cells, iPSCs are made by taking adult cells, such as those from skin or blood, and reprogramming them back into a versatile state. In this form, they can develop into many different kinds of cells in the body.

“We believe that these iPSCs can reliably mature into dopamine-producing brain cells, and offer the best chance of jump-starting the brain’s dopamine production,” said Xenos Mason, MD, a neurologist who specializes in Parkinson’s disease and other movement disorders with Keck Medicine and co-principal investigator of the study.

Brain Implant Procedure and Long Term Monitoring

To deliver the cells, Lee creates a small opening in the skull to reach the brain. Using magnetic resonance imaging (MRI) for guidance, he carefully places the stem cells into the basal ganglia, the region responsible for coordinating movement.

After the operation, participants are closely observed for 12-15 months to track changes in symptoms and watch for potential side effects, including dyskinesia — excess movements — or infection. Researchers plan to continue following patients and monitoring their condition for up to five years.

“Our ultimate goal is to pioneer a technique that can repair patients’ motor function and offer them a better quality of life,” said Lee.

Keck Medicine is one of three sites in the United States taking part in the study. The multisite clinical trial includes 12 people with moderate to moderate-severe Parkinson’s disease.

The stem cell therapy, known as RNDP-001, is produced by Kenai Therapeutics, a biotechnology company focused on developing treatments for neurological disorders. The U.S. Food & Drug Administration has granted the clinical trial, Phase 1 REPLACE™, fast-track designation, which is intended to speed up the development and review process.

Disclosure: Mason has received an honorarium payment from Kenai Therapeutics in the past.