dopamine producing neurons

Creating an on-off switch to test stem cell therapy for Parkinson’s Disease

/ Kevin McCormack / 1 Comment

Sometimes you read about a new study where the researchers did something that just leaves you gob smacked. That’s how I felt when I read a study in the journal Cell Stem Cell about a possible new approach to helping people with Parkinson’s Disease (PD).

More on the gob smacking later. But first the reason for the study.

We know that one of the causes of Parkinson’s disease is the death of dopamine-producing neurons, brain cells that help plan and control body movement. Over the years, researchers have tried different ways to try and replace those cells but getting the cells where they need to be and getting them to integrate into the brain has proved challenging.

A team at the University of Wisconsin-Madison think they may have found a way to fix that. In an article in Drug Target Review  lead researcher Dr. Su-Chun Zhang, explained their approach:

“Our brain is wired in such an accurate way by very 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. Neurological injuries usually affect specific brain regions or specific cell types, disrupting circuits. In order to treat those diseases, we have to restore these circuits.”

The researchers took human embryonic stem cells and transformed them into dopamine-producing neurons, then they transplanted those cells into mice specially bred to display PD symptoms. After several months the team were able to show that not only had the mice improved motor skills but that the transplanted neurons were able to connect to the motor-control regions of the brain and also establish connections with regulatory regions of the brain, which prevented over stimulation. In other words, the transplanted cells looked and behaved the way they would in a healthy human brain.

Now here comes the gob smack part. The team wanted to make sure the cells they transplanted were the reason for the improved motor control in the mice. So, they had inserted a genetic on-and-off switch into the stem cells. By using specially designed drugs the researchers were able to switch the cells on or off.

When the cells were switched off the mice’s motor improvements stopped. When they were switched back on, they were restored.

Brilliant right! Well, I thought it was.

Next step is to test this approach in larger animals and, if all continues to look promising, to move into human clinical trials.

CIRM is already funding one clinical trial in Parkinson’s disease. You can read about it here.

Stem Cells for Parkinson’s Disease

/ Kevin McCormack / Leave a comment

While the world has been turned upside down by the coronavirus pandemic, the virus poses an increased threat to people with Parkinson’s disease (PD). Having a compromised immune system, particularly involving the lungs, means people with PD are at higher risk of some of the more dangerous complications of COVID-19. So, this seems like an appropriate time for CIRM to hold a special Facebook Live “Ask the Stem Cell Team” About Parkinson’s disease.

We are holding the event on Tuesday, May 5th at noon PDT.

The initial reason for the Facebook Live was the CIRM Board approving almost $8 million for Dr. Krystof Bankiewicz at Brain Neurotherapy Bio, Inc. to run a Phase 1 clinical trial targeting PD. Dr. Bankiewicz is using a gene therapy approach to promote the production of a protein called GDNF, which is best known for its ability to protect dopaminergic neurons, the kind of cell damaged by Parkinson’s. The approach seeks to increase dopamine production in the brain, alleviating PD symptoms and potentially slowing down the disease progress.

Dr. Bankiewicz will be joined by two of CIRM’s fine Science Officers, Dr. Lila Collins and Dr. Kent Fitzgerald. They’ll talk about the research targeting Parkinson’s that CIRM is funding plus other promising research taking place.

And we are delighted to have a late addition to the team. Our CIRM Board member and patient advocate for Parkinson’s disease, Dr. David Higgins. David has a long history of advocacy for PD and adds the invaluable perspective of someone living with PD.

As always, we want this to be as interactive as possible, so we want to get your questions. You can do this on the day, posting them alongside the live feed, or you can send them to us ahead of time at info@cirm.ca.gov. We’ll do our best to answer as many as we can on the day, and those we don’t get to during the broadcast we’ll answer in a later blog.

We look forward to seeing you there.

CIRM-funded Stanford study finds potential diagnostic tool, treatment for Parkinson’s

/ Yimy Villa / Leave a comment
Dr. Xinnan Wang, a neurosurgeon and author of a study that has identified a molecular pathway apparently responsible for the death of dopaminergic neurons that causes the symptoms of Parkinson’s.

Of the various neurodegenerative diseases, Parkinson’s is the second most common and affects 35 million people world wide. It is caused by the gradual breakdown of dopaminergic neurons in the brain, which are a type of cell that produce a chemical in your brain known as dopamine.  This decrease in dopamine can cause complications such as uncontrollable shaking of the hands, slowed movement, rigid muscles, loss of automatic movements, speech changes, bladder problems, constipation, and sleep disorders.

Although 5-10% of cases are the result of genetically inherited mutations, the vast majority of cases are sporadic, often involving complex interactions of multiple unknown genes and environmental factors. Unfortunately, it is this unknown element that make the disease very difficult to detect early on in the majority of patients.

However, in a CIRM funded study, Dr. Xinnan Wang and her team at Stanford University were able to pinpoint a molecular defect that seems almost universal in patients with Parkinson’s and those at high risk of acquiring it. This could prove to be a way to detect Parkinson’s in its early stages and before symptoms start to manifest. Furthermore, it could also be used to evaluate a potential treatment’s effectiveness at preventing or stalling the progression of Parkinson’s.

In a Stanford press release, Dr. Wang explains the implications of these findings:

“We’ve identified a molecular marker that could allow doctors to diagnose Parkinson’s accurately, early and in a clinically practical way. This marker could be used to assess drug candidates’ capacity to counter the defect and stall the disease’s progression.” 

What is more astounding is that Dr. Wang and her team were also able to identify a compound that is shown to reverse the defect in cells taken from Parkinson’s patients. In an animal model, the compound was able to prevent the death of neurons, which is the underlying problems in the disease.

In their study, Dr. Wang and her team focused on the mitochondria, which churns out energy and is the powerhouse of the cell. Dopaminergic neurons in the brain are some of the body’s hardest working cells, and it is theorized that they start to die off when the mitochondria burns out after constant, high energy production.

Mitochondria spend much of their time attached to a grid of protein “roads” that crisscross cells. Our cells have a technique for clearing “burnt out” mitochondria, but the process involves removing an adaptor molecule called Miro that attaches mitochondria, damaged or healthy, to the grid. 

Dr. Wang’s team previously identified a mitochondrial-clearance defect in Parkinson’s patients’ cells that involved the inability to remove Miro from damaged mitochondria.

In the current study, they obtained skin samples from 83 Parkinson’s patients, Five patients with asymptomatic close relatives considered to be at heightened risk, 22 patients diagnosed with other movement disorders, and 52 healthy control subjects. They extracted fibroblasts, which are cells common in skin tissue, from the samples and subjected them to a stressful process that messes up mitochondria. 

The researchers found the Miro-removal defect in 78 of the 83 Parkinson’s fibroblasts (94%) and in all five of the “high-risk” samples, but not in fibroblasts from the control group or patients with other movement-disorders.

Next, the team was able to screen over 6.8 million molecules and found 11 that would bind to Miro, initiating separation from the mitochondria, are non-toxic, orally available, and able to cross the blood-brain barrier. These 11 compounds were tested in fruit flies and and ultimately one of them, which seems to target Miro exclusively, was tested on fibroblasts from a patient with sporadic Parkinson’s disease. The compound was found to substantially improved Miro clearance in these cells after their exposure to mitochondria-damaging stress.

Dr. Wang is optimistic that clinical trials of the compound or something similar are no more than a few years off.

In the same Stanford press release, Dr. Wang stated that,

“Our hope is that if this compound or a similar one proves nontoxic and efficacious and we can give it, like a statin drug, to people who’ve tested positive for the Miro-removal defect but don’t yet have Parkinson’s symptoms, they’ll never get it.”

The full results of this study were published in the journal Cell Metabolism.

Approach that inspires DREADD could create new way to treat Parkinson’s disease

/ Kevin McCormack / Leave a comment

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Dopamine producing brain nerve cells, made from embryonic stem cells

Imagine having a treatment for Parkinson’s that acts like a light switch, enabling you to turn it on or off depending on your needs. Well, that’s what researchers at the University of Wisconsin-Madison have come up with. And if it works, it might help change the way we treat many other diseases.

For years researchers have been trying to come up with a way of replacing the dopamine-producing brain nerve cells, or neurons, that are attacked and destroyed by Parkinson’s. Those cells regulate movement and as they are destroyed they diminish a person’s ability to control their body, their movement and even their emotions.

Attempts to transplant dopamine-producing cells into the brains of people with Parkinson’s disease have met with mixed results. In some cases the transplanted cells have worked. In many cases the cells don’t make enough dopamine to control movement. In about 10 percent of cases the cells make too much dopamine, causing uncontrolled movements called graft-induced dyskinesia.

But now the researchers at UW Madison have found a new approach that might change that. Using the gene-editing tool CRISPR (you can read about that here) they reprogrammed embryonic stem cells to become two different types of neurons containing a kind of genetic switch called a DREADD, which stands for designer receptor exclusively activated by designer drug. When they gave mice the designer drug they created to activate DREADD, one group of cells boosted production of dopamine, the other group shut down its dopamine production.

In a news release about the study, which is published in the journal Cell Stem Cell, lead author Su-Chun Zhang says this kind of control is essential in developing safe, effective therapies:

“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 we may need to slow or stop it.”

Zhang says the cells developed using this approach have another big advantage:

“We can turn them on or off, up or down, using a designer drug that can only act on cells that express the designer receptor. The drug does not affect any host cell because they don’t have that specialized receptor. It’s a very clean system.”

Tests in mice showed that the cells, and the designer drug, worked as the researchers hoped they would with some cells producing more dopamine, and others halting production.

It’s an encouraging start but a lot more work needs to be done to make sure the the genetically engineered stem cells, and the designer drug, are safe and that they can get the cells to go to the part of the brain that needs increased dopamine production.

As Zhang says, having a method of remotely controlling the action of transplanted cells, one that is reversible, could create a whole new way of treating diseases.

“This is the first proof of principle, using Parkinson’s disease as the model, but it may apply to many other diseases, and not just neurological diseases.”