Seeing the Light: How Engineered Nerve Cells Might Curb Parkinson’s Disease

Neurons created from embryonic stem cells

Neurons created from embryonic stem cells are manipulated using optogenetics, a tool that shines light on them to change their function.

Stem cell therapy for Parkinson’s disease has shown great promise in animal studies and is moving closer to becoming an option for people affected by this devastating neurological condition. But before it can advance from animal models into human trials, investigators need to learn more about how the therapy works.

Memorial Sloan Kettering stem cell biologist Lorenz Studer and his colleagues have taken a critical step in that direction with their latest study, which provides an unprecedented glimpse into the brains of mice treated with engineered stem cells. Using optogenetics — a tool that controls cells by shining light on them — they’ve been able to decipher how these transplanted cells function in the brain.

Now we have a way to understand how the cells really work.
Lorenz Studer MSK stem cell biologist

“Optogenetics has had a huge impact in neurobiology over the past several years by allowing researchers to study how parts of the brain interact with each other,” Dr. Studer says. “But to my knowledge no one else has used this technology to find out how newly grafted cells in the brain function. Now we have a way to understand how the cells really work.”

Manufacturing Stem Cells

For more than a decade, Dr. Studer’s lab has focused on developing embryonic stem cells as a treatment for Parkinson’s disease, a degenerative disorder caused by the loss of neurons in the brain that produce the hormone dopamine. Dr. Studer and his colleagues have created methods for coaxing embryonic stem cells — which have the potential to form any type of cell in the body — into becoming dopamine neurons by guiding their development.

Using laboratory mice with a Parkinson’s-like disease, the investigators have shown that transplanting these neurons into the brains of the mice alleviates the movement-related symptoms — such as shaking and difficulty moving — that characterize the illness.

“When we put these cells into the brains of a Parkinson’s animal, it takes about four or five months, but eventually the animal recovers from its movement deficits,” Dr. Studer explains. “This is exciting, but the question has been, how do the cells do it? Do they induce the remaining dopamine cells in the brain to function better? Do they perform some kind of signaling function? Or do they actually integrate into the network of the host animal and begin acting like a new part of the brain? This technique allows us to answer those questions.”

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Using Optogenetics to Look Inside the Brain

In the current study, which was published earlier this month in Nature Biotechnology, the team introduced a genetic switch into the stem cell–derived dopamine neurons that would allow the scientists to turn the firing of nerve cells on or off at will by exposing them to light. This manipulation is the basis of optogenetics.

The team, including researchers from Columbia University and Stanford University, was able to show that once the mice had fully recovered from their motor disease symptoms after transplantation, their Parkinson’s-like ailments would return again within minutes if the scientists switched on a laser light that inactivated the newly transplanted cells. When the light was switched off, the animals fully recovered once again.

“This is quite a remarkable demonstration that the grafted cells need to constantly be active through neuronal firing to provide the therapeutic benefit to the animals,” Dr. Studer says. “We also showed that this neuronal activity is linked to increased dopamine release from the grafted cells, indicating that these implanted cells truly integrate into the animal’s brain.”

[Our research indicated] these implanted cells truly integrate into the animal's brain.
Lorenz Studer
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Advancing to Human Trials

“Our thinking in developing this research was that if you’re going to treat patients with these neurons, you should first be able to prove exactly how these nerve grafts work,” says Julius Steinbeck, a postdoctoral researcher in Dr. Studer’s lab who was the study’s first author.

“Understanding how this treatment works will also help us to anticipate potential side effects before we move this into human studies,” he adds.

“There’s still more to learn from studying these implanted cells,” Dr. Studer concludes. “We plan to continue using this tool to get more details about how the grafted cells function.”

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This work was supported by the US National Institutes of Health and its National Institute of Neurological Disorders and Stroke, a New York State Stem Cell Science contract, the Parkinson’s Disease Foundation, the JPB Foundation, and the Morris K. Udall Center of Excellence for Parkinson’s Disease Research.


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How near in the future, do u think there will a cure, or something to slow down progression?

Nancy, thank you for your comment. It is likely to be another few years before the approach discussed in this story can begin being evaluated in human trials. For other developments in research for PD, we recommend you go to this page from the National Institutes of Health:


ISABEL. first and foremost..thank you for serving this great country. Where did you have your stem cell treatment? My dad suffers horribly from this disease. Thank you

my husband has parkinsons. we looked into adult stem cells with dr. in st. Petersburg fl. have decided not to have it done. the f.d.a. has control so every one will get a share of our money & keep us coming back o.k if you have millions.

Does anyone know of any research related to spirituality and Parkinson's Disease? Seems to be an under assessed mechanism of support.

Dear Diane, we agree that spirituality can be an important and helpful form of support for many people. We did a quick search on (which lists all current and completed clinical trials in the country) and couldn’t find any studies studying spirituality in people with Parkinson’s. You may continue to keep track on all studies related to Parkinson’s disease (and their results) here:

We hope this is helpful. Thank you for your comment.

How does one get chosen for human trials?

Dear Michael, every clinical trial has guidelines called “eligibility criteria” that specify who can and cannot participate. The eligibility criteria for a clinical trial are outlined in its protocol. A protocol is a document for doctors that explains all of the details about a clinical trial. Your doctor can review a protocol and help to determine whether you are eligible for a particular trial. To learn more about clinical studies and browse a listing of open trials at MSK, please visit

We hope this information is helpful. Thank you for reaching out to us.

I have Progressive Supranuclear Palsy. And I am on Ayurvedic medicines. Do you need to do cell transplant to cure this disorder ?

Subhash, for more information about this condition, we recommend that you refer to the National Institute of Neurological Disorders and Stroke at the NIH. Here is a link to their fact sheet on progressive supranuclear palsy: Thank you for your comment.


Need urgent advise. My mother is suffering from Parkinson's PSP disease from approx 2 years. And she is also having diabetic from past 20-25 years. She is undergoing medicine prescribed by Neuro surgeons and dr. like syndopa, parkitidin, donap etc plus other diabetic medicines. However there is no good improvement in her health and she frequently falls if there is no support near by. Now the condition is worst and she is on wheel chair. Earlier she was able to walk with support. She also suffers from talking while sleeping and hands moments in sleep. She is very restless and always wants to work but since she could not make body balance, hence falls. Please let me know if there is any cure for this disease in India and what is the procedure. Appreciate your quick response.

Abhishek, the research that is discussed in this article is still being evaluated in the laboratory and is not yet available to Parkinson’s patients. Thank you for your comment.

Hi, my mother is suffering from progressive degenerative disease. 2 years back her symptoms started by falling down often and her left side started to stiffen and it was adverse..her left hand is now totally twisted and cannot be used. Then her left leg and now she totally cannot speak anything. I really wanted to know whether there is any effective treatment. She is now totally bed ridden but still with the help of my father she walks and moves a little..but literally my father has to carry her.
Thank you.

Tulsi, we’re sorry to hear your mother is going through this. The treatments that MSK is developing for Parkinson’s disease are still being studied in the lab and are not yet ready to be evaluated in patients. If you’d like to find out about possible clinical trials for your mother, we recommend you go to, a database of trials around the world and maintained by the US National Institutes of Health. You may be able to find a treatment for your mother close to where you live. Best wishes to you and your family.

Is there an update on this research?