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SA Scientists Study Stem Cell Delivery for Parkinson's

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Wendy Rigby
/
Texas Public Radio
Dopamine neurons light up on an image under a microscope at Texas Biomed

A promising treatment for Parkinson’s disease is getting a boost from a San Antonio researcher. He’s developing precise methods for delivering stem cells to the brain.

  

Parkinson’s disease is a progressive movement disorder where dying neurons in the brain lead to a decrease in dopamine production. Over time, Parkinson’s patients are unable to control their movements normally.

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Credit Wendy Rigby / Texas Public Radio
Marcel Daadi, Ph.D., is director of Stem Cells and Regenerative Medicine at Texas Biomed.

  

"It’s really a terrible disease," said Marcel Daadi, Ph.D., director of Stem Cells and Regenerative Medicine at Texas Biomedical Research Institute. "And there’s really nothing for them out there. There’s really no cure for Parkinson’s disease."

Daadi describes himself as a scientist with a career-long love affair with neurology. "I saw these brain cells and these dopamine neurons and I just fell in love with them," he remembered.

Those are the cells scientists would like to regenerate for Parkinson’s patients. Instead of starting on people, however, animals are the models for now. Baboons and marmosets.

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Credit Texas Biomedical Research Institute
Baboons at the Southwest National Primate Research Center are some of the animal models being used in this stem cell study.

  

 

Here’s how the experiments work. The animals are given a neuro toxin that kills dopamine neurons, creating symptoms strikingly similar to the ones patients with Parkinson’s experience: tremors and slow, impaired movement.

In a video recording at Texas Biomed, you can see the animals being given a test. They try to retrieve a treat before a cage door close, grapes for baboons and marshmallows for marmosets.

The animals’ performance serves as the baseline. Now comes the tricky part: inserting human stem cells into the right part of the primate’s brain in the right amount to try and reverse the decrease in dopamine production. These human stem cells can be derived from skin cells or blood cells, for example, and then genetically engineered to become stem cells.

"It’s a cell that has the ability to give rise to any cell type in the body," Daadi explained.

With the help of imaging experts at the University of Texas Health Science Center at San Antonio, Daadi is using magnetic resonance imaging, or MRIs, to deliver the stem cells to the animals precisely where they need to go, safely and in the right quantity. With this technology, Daddi said the injection is accurate, very accurate, pinpointing the location with a margin of error less than a millimeter.

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Credit Wendy Rigby / Texas Public Radio
Geoffrey Clarke, Ph.D., is a professor of radiology at the UT Health Science Center.

  

"So you can really see the area of disease you want to put these cells in," Daddi said. "I believe it’s one of the key obstacles to really guarantee safety and efficacy to patients."

Geoffrey Clarke, Ph.D., of the Health Science Center explained the stem cells are loaded with a small amount of a tracing agent. "When you inject the stem cells into the brain, the cell shows up as a black spot. So we know that the cells have gone there and we can even image them after and for several days and weeks following the procedure," Clarke stated. "The cells don’t just stay in one place. They’re living and they’ll migrate and merge with cells in the brain to hopefully enhance their function. That’s the whole purpose of the treatment."

The treated animals are scanned with Positron Emission Tomography or PET scans to provide an image of the brain so scientists can make sure the cells are there and functioning. If they are still in the right place lighting up the screen weeks after, that’s a good sign according to Clarke.

"We know that that part of the brain is working properly, or better than it was before at least," Clarke said.

Follow up behavior testing of the animals will help prove if the therapy is working.

Effective targeted delivery of stem cells has been one of the bottlenecks to trying this therapy on humans, but Daadi is confident this and thousands of other experiments worldwide on Parkinson’s will lead to significant breakthroughs in the use of stem cells soon.

"Once we put them into the brain, we know 100 percent they’re going to innervate and they’re going to function. And they’re going to function for the rest of the life of the patient.," Daadi claimed "So it’s really a cure."

Daadi speculates human trials could begin in two to five years. He’s invested in a startup biotech company in San Antonio to develop, manufacture and commercialize these stem cells for public use.

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Credit Wendy Rigby / Texas Public Radio
Marcel Daadi, Ph.D., and his team are working on an effective delivery system for stem cells to treat Parkinson's disease.