It’s not unusual for television to accelerate medical innovation.Take the current season as an example Grey’s Anatomy, the main storyline of which is about “curing” Parkinson’s disease. The show tells the story of a team of researchers and doctors who use skin stem cells to perform a groundbreaking procedure.
In real life, despite decades of research and tremendous technological know-how in stem cell therapies for Parkinson’s disease, these treatments remain out of reach for most Parkinson’s patients. Parkinson’s disease is a brain disease that worsens over time and causes the death of certain nerve cells that normally produce dopamine, which helps coordinate muscle movement. The most common surgical treatment for Parkinson’s disease is deep brain stimulation, which delivers electrical impulses to areas of the brain that affect motor symptoms such as tremors and stiffness.
Still, given the risk this chronic, progressive neurological disease poses to an estimated 1 million Americans, it’s important to know whether Hollywood’s depictions are far-fetched.
In the show, doctors remove stem cells from skin biopsies of Parkinson’s patients and convert the cells into dopamine-producing cells “through a complex process.” People with Parkinson’s disease often have lower dopamine levels in the putamen, the part of the brain involved in movement. By injecting new dopamine-producing cells into the character’s forebrain (where the putamen is located), doctors aim to increase dopamine levels.
The surgery begins with a CT scan, which provides the surgical team with an image of an “interactive 3D road map” of the character’s brain. After a few quick steps, including drilling a hole to prevent pressure from building up in the brain, a robotic arm secures a hollow needle in place. The researchers then removed the stem cells from the cooler and examined them under a microscope to confirm that enough cells survived. Finally, cells were injected into the character’s forebrain, starting on one side and then moving to the other.
Willard Kassoff, MD, associate professor of neurosurgery at the Lewis Katz School of Medicine at Temple University and chief of stereotaxic and functional neurosurgery at Temple University Hospital, said much of what is depicted in the show is realistic — albeit Simplified and futuristic.
“This is not science fiction, this is the show of the future,” he said.
There have been some exciting stem cell innovations for Parkinson’s disease in recent years that, on the surface, are reminiscent of Grey’s AnatomyTelevised “The Cure.”
For example, in 2017 and 2018, doctors reprogrammed skin cells taken from Parkinson’s patients to create “replacement dopamine neurons” and implanted them into the person’s brain. A recent clinical trial involved injecting stem cells into the brains of Parkinson’s patients to restore their dopamine levels, and using GPS-like brain scans to show neurosurgeons the location of the injected cells. Upcoming clinical trials will also use skin cells from Parkinson’s patients to produce replacement dopamine neurons for transplantation.
But Kassoff says the treatment won’t necessarily become widely available anytime soon. “Cell transplantation is very difficult and complex,” he said.
Some treatments rely on genetic engineering to convert stem cells into neural progenitor cells, which can transform into the various cell types found in the brain, a process called differentiation.Neurosurgeons can also direct how Neural progenitor cells undergo changes that, for example, guide them to become dopamine neurons. The hope is that once these cells are transplanted into the brain, they will “figure out what to do or be told what to do by surrounding cells,” Kassoff said.
Even if the trial is successful, it may not represent a cure. Because treatments target the putamen and substantia nigra (regions where neuronal loss affects dopamine levels), they only address motor symptoms. Parkinson’s disease can also affect thinking, balance and other functions throughout the body. Cognitive decline can lead to dementia and death.
“The idea that putting cells into the substantia nigra or putamen can cure Parkinson’s disease is probably not correct,” Kassoff said.
Additionally, Parkinson’s disease is generally thought to be a disease of one cell type: dopaminergic cells in the substantia nigra. But in reality, Kassoff explained, this could be a disease with “thousands of cell types,” making any potential stem cell-derived therapies extremely complex. Type 1 diabetes, on the other hand, is a disease in which only one cell type exists, and new treatments using insulin-producing cells derived from stem cells may be a cure.
As for Parkinson’s disease, Kassoff said, “The next stem cell trial may hit the jackpot, and then we’ll move on to the next step.” For example, that could mean figuring out where to transplant stem cells to treat cognitive and balance-related symptoms of the disease.
Ultimately, he said, “Hopefully what happens on the show is what’s going to happen at some point in the future.”
