Itâs not unusual for TV to fast-track medical innovation. Take the current season of Greyâs Anatomy, which featured a major storyline about a âcureâ for Parkinsonâs disease. The drama series followed a team of researchers and doctors as they used a groundbreaking surgical procedure using skin-derived stem cells.
In real life, despite decades of research and huge gains in technical knowledge around stem cell therapies for Parkinsonâs disease, those treatments remain out of reach for most people with the disease. Parkinson’s is a brain disorder that worsens over time and causes the death of certain nerve cells that normally produce dopamine, which helps coordinate muscle movement. The most commonly used surgical treatment for Parkinsonâs is deep brain stimulation, which delivers electrical pulses to brain areas affecting motor symptoms, such as tremors and rigidity.
Still, given the stakes of this chronic progressive neurological disease facing about 1 million Americans, itâs worth unpacking just how far-fetched the Hollywood depiction is â or isnât.
On the show, doctors take stem cells from a skin biopsy of a character with Parkinson’s disease and, âthrough a complex process,â transform those cells into dopamine-producing cells. People with Parkinsonâs typically have low dopamine levels in the putamen, a part of the brain involved in movement. By injecting new dopamine-producing cells into the character’s forebrain, where the putamen is found, the doctors aim to boost dopamine levels.
The procedure kicks off with a CT scan, which gives the surgical team images of whatâs described as âan interactive 3D roadmapâ of the characterâs brain. After a few more quick steps â including drilling of burr holes to prevent pressure from building up in the brain â a robotic arm brings a hollow needle into place. A researcher then removes the stem cells from a cooler and examines them under a microscope to confirm that enough cells are alive. Finally, the cells are injected into the characterâs forebrain, starting with one side and then moving to the other.
Much of whatâs depicted on the show is realistic â if simplified and futuristic â according to Willard Kasoff, MD, an associate professor of neurosurgery at the Lewis Katz School of Medicine at Temple University and director of stereotactic and functional neurosurgery at Temple University Hospital.
âIt’s not science fiction, but it’s a future show,â he says.
There have been several exciting stem cell innovations targeting Parkinsonâs in recent years that, on the surface, are reminiscent of Greyâs Anatomyâs televised âcure.â
In 2017 and 2018, for instance, doctors reprogrammed skin cells taken from a person with Parkinsonâs to create âreplacement dopamine neurons,” which got implanted into the personâs brain. More recently, a clinical trial involved injecting stem cells into the brains of people with Parkinson’s in order to restore their dopamine levels, complete with a GPS-like brain scan showing neurosurgeons where to inject the cells. Upcoming clinical trials will also use Parkinsonâs patientsâ skin cells to produce replacement dopamine neurons for transplantation.
But such treatments wonât necessarily be widely available anytime soon, according to Kasoff. “Cell transplantation is incredibly difficult and complicated,â he says. âIt’s been worked on for decades, and it’s still early, early research trials. So even that kind of therapy is likely years and years away.â
Some of the therapies rely on genetic engineering to convert stem cells into neural progenitor cells, which can change into various cell types found in the brain â a process known as differentiating. Neurosurgeons can also direct how neural progenitor cells change, such as guiding them to become dopamine neurons. The hope is that once those cells are transplanted into the brain, theyâll âfigure out what to do, or be told what to do by the surrounding cells,â says Kasoff.
Even if the trials succeed, they may not represent a cure. Because the treatments are directed at the putamen and the substantia nigra (an area where neuron loss can affect dopamine levels), they only address motor symptoms. Parkinsonâs disease also affects thinking skills, balance, and other functions throughout the body. Cognitive decline can lead to dementia and death.
âThe idea that you can cure Parkinson’s by putting cells in the substantia nigra or the putamen is probably not true,â Kasoff says.
Also, Parkinsonâs is often thought of as a disease of one cell type: the dopaminergic cells in the substantia nigra. But in reality, Kasoff explains, itâs likely a disease with âthousands of cell types,â which makes any potential stem cell-derived cure extremely complex. Type 1 diabetes, on the other hand, is a disease of only one cell type, and new treatments using insulin-producing cells derived from stem cells could amount to a cure.
As for Parkinsonâs, says Kasoff, âit may be that the next stem cell trial hits the jackpot, and then we’ll be on to the next step.â That could mean figuring out where to transplant stem cells for the cognitive and balance-related symptoms of the disease, for instance.
Ultimately, he says, âthe hope is that what happens on the show is exactly what will happen at some point in the future.â
