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.
A few weeks ago we held a Facebook Live “Ask the Stem Cell Team About Parkinson’s Disease” event. As you can imagine we got lots of questions but, because of time constraints, only had time to answer a few. Thanks to my fabulous CIRM colleagues, Dr. Lila Collins and Dr. Kent Fitzgerald, for putting together answers to some of the other questions. Here they are.
Q:It seems like we have been hearing for years that stem cells can help people with Parkinson’s, why is it taking so long?
A: Early experiments in Sweden using fetal tissue did provide a proof of concept for the strategy of replacing dopamine producing cells damaged or lost in Parkinson’s disease (PD) . At first, this seemed like we were on the cusp of a cell therapy cure for PD, however, we soon learned based on some side effects seen with this approach (in particular dyskinesias or uncontrollable muscle movements) that the solution was not as simple as once thought.
While this didn’t produce the answer it did provide some valuable lessons.
The importance of dopaminergic (DA) producing cell type and the location in the brain of the transplant. Simply placing the replacement cells in the brain is not enough. It was initially thought that the best site to place these DA cells is a region in the brain called the SN, because this area helps to regulate movement. However, this area also plays a role in learning, emotion and the brains reward system. This is effectively a complex wiring system that exists in a balance, “rewiring” it wrong can have unintended and significant side effects.
Another factor impacting progress has been understanding the importance of disease stage. If the disease is too advanced when cells are given then the transplant may no longer be able to provide benefit. This is because DA transplants replace the lost neurons we use to control movement, but other connected brain systems have atrophied in response to losing input from the lost neurons. There is a massive amount of work (involving large groups and including foundations like the Michael J Fox Foundation) seeking to identify PD early in the disease course where therapies have the best chance of showing an effect. Clinical trials will ultimately help to determine the best timing for treatment intervention.
Ideally, in addition to the cell therapies that would replace lost or damaged cells we also want to find a therapy that slows or stops the underlying biology causing progression of the disease.
So, I think we’re going to see more gene therapy trials including those targeting the small minority of PD that is driven by known mutations. In fact, Prevail Therapeutics will soon start a trial in patients with GBA1 mutations. Hopefully, replacing the enzyme in this type of genetic PD will prevent degeneration.
And, we are also seeing gene therapy approaches to address forms of PD that we don’t know the cause, including a trial to rescue sick neurons with GDNF which is a neurotrophic factor (which helps support the growth and survival of these brain cells) led by Dr Bankiewicz and trials by Axovant and Voyager, partnered with Neurocrine aimed at restoring dopamine generation in the brain.
A small news report came out earlier this year about a recently completed clinical trial by Roche Pharma and Prothena. This addressed the build up in the brain of what are called lewy bodies, a problem common to many forms of PD. While the official trial results aren’t published yet, a recent press release suggests reason for optimism. Apparently, the treatment failed to statistically improve the main clinical measurement, but other measured endpoints saw improvement and it’s possible an updated form of this treatment will be tested again in the hopes of seeing an improved effect.
Finally, I’d like to call attention to the G force trials. Gforce is a global collaborative effort to drive the field forward combining lessons learned from previous studies with best practices for cell replacement in PD. These first-in-human safety trials to replace the dopaminergic neurons (DANs) damaged by PD have shared design features including identifying what the best goals are and how to measure those.
And the Summit PD trial, Dr Jeanne Loring of Aspen Neuroscience.
Taken together these should tell us quite a lot about the best way to replace these critical neurons in PD.
As with any completely novel approach in medicine, much validation and safety work must be completed before becoming available to patients
The current approach (for cell replacement) has evolved significantly from those early studies to use cells engineered in the lab to be much more specialized and representing the types believed to have the best therapeutic effects with low probability of the side effects (dyskinesias) seen in earlier trials.
If we don’t really know the cause of Parkinson’s disease, how can we cure it or develop treatments to slow it down?
PD can now be divided into major categories including 1. Sporadic, 2. Familial.
For the sporadic cases, there are some hallmarks in the biology of the neurons affected in the disease that are common among patients. These can be things like oxidative stress (which damages cells), or clumps of proteins (like a-synuclein) that serve to block normal cell function and become toxic, killing the DA neurons.
The second class of “familial” cases all share one or more genetic changes that are believed to cause the disease. Mutations in genes (like GBA, LRRK2, PRKN, SNCA) make up around fifteen percent of the population affected, but the similarity in these gene mutations make them attractive targets for drug development.
CIRM has funded projects to generate “disease in a dish” models using neurons made from adults with Parkinson’s disease. Stem cell-derived models like this have enabled not only a deep probing of the underlying biology in Parkinson’s, which has helped to identify new targets for investigation, but have also allowed for the testing of possible therapies in these cell-based systems.
iPSC-derived neurons are believed to be an excellent model for this type of work as they can possess known familial mutations but also show the rest of the patients genetic background which may also be a contributing factor to the development of PD. They therefore contain both known and unknown factors that can be tested for effective therapy development.
I have heard of scientists creating things called brain organoids, clumps of brain cells that can act a little bit like a brain. Can we use these to figure out what’s happening in the brain of people with Parkinson’s and to develop treatments?
There is considerable excitement about the use of brain organoids as a way of creating a model for the complex cell-to-cell interactions in the brain. Using these 3D organoid models may allow us to gain a better understanding of what happens inside the brain, and develop ways to treat issues like PD.
The organoids can contain multiple cell types including microglia which have been a hot topic of research in PD as they are responsible for cleaning up and maintaining the health of cells in the brain. CIRM has funded the Salk Institute’s Dr. Fred Gage’s to do work in this area.
If you go online you can find lots of stem cells clinics, all over the US, that claim they can use stem cells to help people with Parkinson’s. Should I go to them?
In a word, no! These clinics offer a wide variety of therapies using different kinds of cells or tissues (including the patient’s own blood or fat cells) but they have one thing in common; none of these therapies have been tested in a clinical trial to show they are even safe, let alone effective. These clinics also charge thousands, sometimes tens of thousands of dollars these therapies, and because it’s not covered by insurance this all comes out of the patient’s pocket.
These predatory clinics are peddling hope, but are unable to back it up with any proof it will work. They frequently have slick, well-designed websites, and “testimonials” from satisfied customers. But if they really had a treatment for Parkinson’s they wouldn’t be running clinics out of shopping malls they’d be operating huge medical centers because the worldwide need for an effective therapy is so great.
Here’s a link to the page on our website that can help you decide if a clinical trial or “therapy” is right for you.
Is it better to use your own cells turned into brain cells, or cells from a healthy donor?
This is the BIG question that nobody has evidence to provide an answer to. At least not yet.
Let’s start with the basics. Why would you want to use your own cells? The main answer is the immune system. Transplanted cells can really be viewed as similar to an organ (kidney, liver etc) transplant. As you likely know, when a patient receives an organ transplant the patient’s immune system will often recognize the tissue/organ as foreign and attack it. This can result in the body rejecting what is supposed to be a life-saving organ. This is why people receiving organ transplants are typically placed on immunosuppressive “anti-rejection “drugs to help stop this reaction.
In the case of transplanted dopamine producing neurons from a donor other than the patient, it’s likely that the immune system would eliminate these cells after a short while and this would stop any therapeutic benefit from the cells. A caveat to this is that the brain is a “somewhat” immune privileged organ which means that normal immune surveillance and rejection doesn’t always work the same way with the brain. In fact analysis of the brains collected from the first Swedish patients to receive fetal transplants showed (among other things) that several patients still had viable transplanted cells (persistence) in their brains.
Transplanting DA neurons made from the patient themselves (the iPSC method) would effectively remove this risk of the immune system attack as the cells would not be recognized as foreign.
CIRM previously funded a discovery project with Jeanne Loring from Scripps Research Institute that sought to generate DA neurons from Parkinson’s patients for use as a potential transplant therapy in these same patients. This project has since been taken on by a company formed, by Dr Loring, called Aspen Neuroscience. They hope to bring this potential therapy into clinical trials in the near future.
A commonly cited potential downside to this approach is that patients with genetic (familial) Parkinson’s would be receiving neurons generated with cells that may have the same mutations that caused the problem in the first place. However, as it can typically take decades to develop PD, these cells could likely function for a long time. and prove to be better than any current therapies.
Creating cells from each individual patient (called autologous) is likely to be very expensive and possibly even cost-prohibitive. That is why many researchers are working on developing an “off the shelf” therapy, one that uses cells from a donor (called allogeneic)would be available as and when it’s needed.
When the coronavirus happened, it seemed as if overnight the FDA was approving clinical trials for treatments for the virus. Why can’t it work that fast for Parkinson’s disease?
While we don’t know what will ultimately work for COVID-19, we know what the enemy looks like. We also have lots of experience treating viral infections and creating vaccines. The coronavirus has already been sequenced, so we are building upon our understanding of other viruses to select a course to interrupt it. In contrast, the field is still trying to understand the drivers of PD that would respond to therapeutic targeting and therefore, it’s not precisely clear how best to modify the course of neurodegenerative disease. So, in one sense, while it’s not as fast as we’d like it to be, the work on COVID-19 has a bit of a head start.
Much of the early work on COVID-19 therapies is also centered on re-purposing therapies that were previously in development. As a result, these potential treatments have a much easier time entering clinical trials as there is a lot known about them (such as how safe they are etc.). That said, there are many additional therapeutic strategies (some of which CIRM is funding) which are still far off from being tested in the clinic.
The concern of the Food and Drug Administration (FDA) is often centered on the safety of a proposed therapy. The less known, the more cautious they tend to be.
As you can imagine, transplanting cells into the brain of a PD patient creates a significant potential for problems and so the FDA needs to be cautious when approving clinical trials to ensure patient safety.
On the surface, actor Michael J. Fox, singer Neil Diamond, civil rights activist Jesse Jackson and Scottish comedian Billy Connolly would appear to have little in common. Except for one thing. They all have Parkinson’s Disease (PD).
Their celebrity status has helped raise public awareness about the condition, but studies show that awareness doesn’t amount to an understanding of PD or the extent to which it impacts someone’s life. In fact a study in the UK found that many people still don’t think PD is a serious condition.
To try and help change that people around the world will be
holding events today, April 11th, World Parkinson’s Day.
The disease was first described by James Parkinson in 1817 in “An Essay on the Shaking Palsy”. In the essay Parkinson described a pattern of trembling in the hands and fingers, slower movement and loss of balance. Our knowledge about the disease has advanced in the last 200 years and now there are treatments that can help slow down the progression of the disease. But those treatments only last for a while, and so there is a real need for new treatments.
That’s what Jun Takahashi’s team at Kyoto University in
Japan hope to provide. In a first-of-its-kind procedure they took skin cells
from a healthy donor and reprogrammed them to become induced pluripotent stem
cells (iPSCs), or stem cells that become any type of cell. These iPSCs were
then turned into the precursors of dopamine-producing neurons, the cells
destroyed by PD, and implanted into 12 brain regions known to be hotspots for
was carried out in October and the patient, a male in his 50s, is still
healthy. If his symptoms continue to improve and he doesn’t experience any bad
side effects, he will receive a second dose of dopamine-producing stem
cells. Six other patients are scheduled to receive this same treatment.
Earlier tests in monkeys showed that the implanted stem cells improved Parkinson’s symptoms without causing any serious side effects.
Scientists at UC San
Francisco are trying a different approach, using gene therapy to tackle one of
the most widely recognized symptoms of PD, muscle movement.
In the study,
published in the journal Annals
of Neurology, the team used
an inactive virus to deliver a gene to boost production of dopamine in the
brain. In a Phase 1 clinical trial 15 patients, whose medication was no longer
able to fully control their movement disorder, were treated with this approach.
Not only were they able to reduce their medication – up to 42 percent in some
cases – the medication they did take lasted longer before causing dyskinesia,
an involuntary muscle movement that is a common side effect of the PD
In a news article Dr. Chad Christine, the first author of the
study, says this approach may also help reduce other symptoms.
“Since many patients were able to substantially
reduce the amount of Parkinson’s medications, this gene therapy treatment may
also help patients by reducing dose-dependent side effects, such as sleepiness
At CIRM we have
a long history of funding research into PD. Over the years we have invested
more than $55 million to try and develop new treatments for the disease.
In June 2018, the CIRM Board awarded $5.8 million to UC San Francisco’s Krystof Bankiewicz and Cedars-Sinai’s Clive Svendsen. They are using neural progenitor cells, which have the ability to multiply and turn into other kinds of brain cells, and engineering them to express the growth factor GDNF which is known to protect the cells damaged in PD. The hope is that when transplanted into the brain of someone with PD, it will help slow down, or even halt the progression of the disease.
The CIRM funding
will hopefully help the team do the pre-clinical research needed to get the
FDA’s go-ahead to test this approach in a clinical trial.
At the time of the award David Higgins, PhD, the CIRM Board Patient Advocate for Parkinson’s Disease, said: “One of the big frustrations for people with Parkinson’s, and their families and loved ones, is that existing therapies only address the symptoms and do little to slow down or even reverse the progress of the disease. That’s why it’s important to support any project that has the potential to address Parkinson’s at a much deeper, longer-lasting level.”
But we don’t just fund the research, we try to bring the scientific community together to help identify obstacles and overcome them. In March of 2013, in collaboration with the Center for Regenerative Medicine (CRM) of the National Institutes of Health (NIH), we held a two-day workshop on cell therapies for Parkinson’s Disease. The experts outlined the steps needed to help bring the most promising research to patients.
Around one million Americans are currently living with Parkinson’s Disease. Worldwide the number is more than ten million. Those numbers are only expected to increase as the population ages. There is clearly a huge need to develop new treatments and, hopefully one day, a cure.
Till then days like April 11th will be an
opportunity to remind ourselves why this work is so important.
April 11th is World Parkinson’s Disease Awareness Day. To mark the occasion, we’re featuring the work of CIRM-funded researchers who are pursuing new, promising ideas to treat patients with this debilitating neurodegenerative disease.
Research: Birgitt and her team at the Parkinson’s Institute in Sunnyvale, California, are using CRISPR gene editing technology to reduce the levels of a toxic protein called alpha synuclein, which builds up in the dopaminergic brain cells affected by Parkinson’s disease.
“My hope is that I can contribute to stopping disease progression in Parkinson’s. If we can develop a drug that can get rid of accumulated protein in someone’s brain that should stop the cells from dying. If someone has early onset PD and a slight tremor and minor walking problems, stopping the disease and having a low dose of dopamine therapy to control symptoms is almost a cure.”
Parkinson’s disease in a dish. Dopaminergic neurons made from Parkinson’s patient induced pluripotent stem cells. (Image credit: Birgitt Schuele)
Research: Jeanne Loring and her team at the Scripps Research Institute in La Jolla, California, are deriving dopaminergic neurons from the iPSCs of Parkinson’s patients. Their goal is to develop a personalized, stem cell-based therapy for PD.
“We are working toward a patient-specific neuron replacement therapy for Parkinson’s disease. By the time PD is diagnosed, people have lost more than half of their dopamine neurons in a specific part of the brain, and loss continues over time. No drug can stop the loss or restore the neurons’ function, so the best possible option for long term relief of symptoms is to replace the dopamine neurons that have died. We do this by making induced pluripotent stem cells from individual PD patients and turning them into the exact type of dopamine neuron that has been lost. By transplanting a patient’s own cells, we will not need to use potentially dangerous immunosuppressive drugs. We plan to begin treating patients in a year to two years, after we are granted FDA approval for the clinical therapy.”
Skin cells from a Parkinson’s patient (left) were reprogrammed into induced pluripotent stem cells (center) that were matured into dopaminergic neurons (right) to model Parkinson’s disease. (Image credit: Jeanne Loring)
Research: Justin Cooper-White and his team at Scaled Biolabs in San Francisco are developing a tool that will make clinical-grade dopaminergic neurons from the iPSCs of PD patients in a rapid and cost-effective manner.
“Treating Parkinson’s disease with iPSC-derived dopaminergic neuron transplantation has a strong scientific and clinical rationale. Even the best protocols are long and complex and generally have highly variable quality and yield of dopaminergic neurons. Scaled Biolabs has developed a technology platform based on high throughput microfluidics, automation, and deep data which can optimize and simplify the road from iPSC to dopaminergic neuron, making it more efficient and allowing a rapid transition to GMP-grade derivation of these cells. In our first 6 months of CIRM-funded work, we believe we have already accelerated and simplified the production of a key intermediate progenitor population, increasing the purity from the currently reported 40-60% to more than 90%. The ultimate goal of this work is to get dopaminergic neurons to the clinic in a robust and economical manner and accelerate treatment for Parkinson’s patients.”
High throughput differentiation of dopaminergic neuron progenitors in microbioreactor chambers in Scaled Biolabs’ cell optimization platform. Different chambers receive different differentiation factors, so that optimal treatments for conversion to dual-positive cells can be determined (blue: nuclei, red: FOXA2, green: LMX1A).
Research: Xinnan Wang and her team at Stanford University are studying the role of mitochondrial dysfunction in the brain cells affected in Parkinson’s disease.
“Mitochondria are a cell’s power plants that provide almost all the energy a cell needs. When these cellular power plants are damaged by stressful factors present in aging neurons, they release toxins (reactive oxygen species) to the rest of the neuron that can cause neuronal cell death (neurodegeneration). We hypothesized that in Parkinson’s mutant neurons, mitochondrial quality control is impaired thereby leading to neurodegeneration. We aimed to test this hypothesis using neurons directly derived from Parkinson’s patients (induced pluripotent stem cell-derived neurons).”
Dopaminergic neurons derived from human iPSCs shown in green, yellow and red. (Image credit: Atossa Shaltouki, Stanford)
Experiments by a team of NIH-funded scientists suggests a potential method for halting the expansion of certain brain tumors.Michelle Monje, M.D., Ph.D., Stanford University.
Scientists at Stanford Medicine discovered that you can halt aggressive brain cancers called high-grade gliomas by cutting off their supply of a signaling protein called neuroligin-3. Their research, which was funded by CIRM and the NIH, was published this week in the journal Nature.
The Stanford team, led by senior author Michelle Monje, had previously discovered that neuroligin-3 dramatically spurred the growth of glioma cells in the brains of mice. In their new study, the team found that removing neuroligin-3 from the brains of mice that were transplanted with human glioma cells prevented the cancer cells from spreading.
“We thought that when we put glioma cells into a mouse brain that was neuroligin-3 deficient, that might decrease tumor growth to some measurable extent. What we found was really startling to us: For several months, these brain tumors simply didn’t grow.”
The team is now exploring whether targeting neuroligin-3 will be an effective therapeutic treatment for gliomas. They tested two inhibitors of neuroligin-3 secretion and saw that both were effective in stunting glioma growth in mice.
Because blocking neuroligin-3 doesn’t kill glioma cells and gliomas eventually find ways to grow even in the absence of neuroligin-3, Monje is now hoping to develop a combination therapy with neuroligin-3 inhibitors that will cure patients of high-grade gliomas.
“We have a really clear path forward for therapy; we are in the process of working with the company that owns the clinically characterized compound in an effort to bring it to a clinical trial for brain tumor patients. We will have to attack these tumors from many different angles to cure them. Any measurable extension of life and improvement of quality of life is a real win for these patients.”
Parkinson’s Institute CIRM Research Featured on KTVU News.
The Bay Area Parkinson’s Institute and Clinical Center located in Sunnyvale, California, was recently featured on the local KTVU news station. The five-minute video below features patients who attend the clinic at the Parkinson’s Institute as well as scientists who are doing cutting edge research into Parkinson’s disease (PD).
Parkinson’s disease in a dish. Dopaminergic neurons made from PD induced pluripotent stem cells. (Image courtesy of Birgitt Schuele).
One of these scientists is Dr. Birgitt Schuele, who recently was awarded a discovery research grant from CIRM to study a new potential therapy for Parkinson’s using human induced pluripotent stem cells (iPSCs) derived from PD patients. Schuele explains that the goal of her team’s research is to “generate a model for Parkinson’s disease in a dish, or making a brain in a dish.”
It’s worth watching the video in its entirety to learn how this unique institute is attempting to find new ways to help the growing number of patients being diagnosed with this degenerative brain disease.
Every year on the second Wednesday of October is Stem Cell Awareness Day (SCAD). This is a day that our agency started back in 2009, with a proclamation by former California Mayor Gavin Newsom, to honor the important accomplishments made in the field of stem cell research by scientists, doctors and institutes around the world.
This year, SCAD is on October 11th. Our Agency will be celebrating this day with a special patient advocate event on Tuesday October 10th at the UC Davis MIND Institute in Sacramento California. CIRM grantees Dr. Jan Nolta, the Director of UC Davis Institute for Regenerative Cures, and Dr. Diana Farmer, Chair of the UC Davis Department of Surgery, will be talking about their CIRM-funded research developing stem cell models and potential therapies for Huntington’s disease and spina bifida (a birth defect where the spinal cord fails to fully develop). You’ll also hear an update on CIRM’s progress from our President and CEO (Interim), Maria Millan, MD, and Chairman of the Board, Jonathan Thomas, PhD, JD. If you’re interested in attending this event, you can RSVP on our Eventbrite Page.
Be sure to check out a list of other Stem Cell Awareness Day events during the month of October on our website. You can also follow the hashtag #StemCellAwarenessDay on Twitter to join in on the celebration!
One last thing. October is an especially fun month because we also get to celebrate Pluripotency Day on October 4th. OCT4 is an important gene that maintains stem cell pluripotency – the ability of a stem cell to become any cell type in the body – in embryonic and induced pluripotent stem cells. Because not all stem cells are pluripotent (there are adult stem cells in your tissues and organs) it makes sense to celebrate these days separately. And who doesn’t love having more reasons to celebrate science?
April is Parkinson’s disease Awareness Month. This year the date is particularly significant because 2017 is the 200th anniversary of the publication of British apothecary James Parkinson’s “An Essay on the Shaking Palsy”, which is now recognized as a seminal work in describing the disease.
To mark the occasion we talked with Dr. Birgitt Schuele, Director Gene Discovery and Stem Cell Modeling at the Parkinson’s Institute and Clinical Center in Sunnyvale, California. Dr. Schuele recently received funding from CIRM for a project using new gene-editing technology to try and halt the progression of Parkinson’s.
What got you interested in Parkinson’s research?
People ask if I have family members with Parkinson’s because a lot of people get into this research because of a family connection, but I don’t. I was always excited by neuroscience and how the brain works, and I did my medical residency in neurology and had a great mentor who specialized in the neurogenetics of Parkinson’s. That helped fuel my interest in this area.
I have been in this field for 15 years, and over time I have gotten to know a lot of people with Parkinson’s and they have become my friends, so now I’m trying to find answers and also a cure for Parkinson’s. For me this has become personal.
I have patients that I talk to every couple of months and I can see how their disease is progressing, and especially for people with early or young onset Parkinson’s. It’s devastating. It has a huge effect on the person and their family, and on relationships, even how they have to talk to their kids about their risk of getting the disease themselves. It’s hard to see that and the impact it has on people’s lives. And because Parkinson’s is progressive, I get to see, over the years, how it affects people, it’s very hard.
Talk about the project you are doing that CIRM is funding
It’s very exciting. The question for Parkinson’s is how do you stop disease progression, how do you stop the neurons from dying in areas affected by the disease. One protein, identified in 1997 as a genetic form of Parkinson’s, is alpha-synuclein. We know from studying families that have Parkinson’s that if you have too much alpha-synuclein you get early onset, a really aggressive form of Parkinson’s.
I followed a family that carries four copies of this alpha-synuclein gene (two copies is the normal figure) and the age of onset in this family was in their mid 30’s. Last year I went to a funeral for one of these family members who died from Parkinson’s at age 50.
We know that this protein is bad for you, if you have too much it kills brains cells. So we have an idea that if you lower levels of this protein it might be an approach to stop or shield those cells from cell death.
We are using CRISPR gene editing technology to approach this. In the Parkinson’s field this idea of down-regulation of alpha-synuclein protein isn’t new, but previous approaches worked at the protein level, trying to get rid of it by using, for example, immunotherapy. But instead of attacking the protein after it has been produced we are starting at the genomic level. We want to use CRISPR as a way to down-regulate the expression of the protein, in the same way we use a light dimmer to lower the level of light in a room.
But this is a balancing act. Too much of the protein is bad, but so is too little. We know if you get rid of the protein altogether you get negative effects, you cause complications. So we want to find the right level and that’s complex because the right level might vary from person to person.
We are starting with the most extreme levels, with people who have twice as much of this protein as is normal. Once we understand that better, then we can look at people who have levels that are still higher than normal but not at the upper levels we see in early-onset Parkinson’s. They have more subtle changes in their production or expression of this protein. It’s a little bit of a juggling act and it might be different for different patients. We start with the most severe ones and work our way to the most common ones.
One of the frustrations I often hear from patients is that this is all taking so long. Why is that?
Parkinson’s has been overall frustrating for researchers as well. Around 100 years ago, Dr. Lewy first described the protein deposits and the main neuropathology in Parkinson’s. About 20 years ago, mutations in the alpha-synuclein gene were discovered, and now we know approximately 30 genes that are associated with, or can cause Parkinson’s. But it was all very descriptive. It told us what is going on but not why.
Maybe we thought it was straight forward and maybe researchers only focused on what we knew at that point. In 1957, the neurotransmitter dopamine was identified and since the 1960s people have focused on Parkinson’s as a dopamine-deficient problem because we saw the amazing effects L-Dopa had on patients and how it could help ease their symptoms.
But I would say in the last 15 years we have looked at it more closely and realized it’s more complicated than that. There’s also a loss of sense of smell, there’s insomnia, episodes of depression, and other things that are not physical symptoms. In the last 10 years or so we have really put the pieces together and now see Parkinson’s as a multi-system disease with neuronal cell death and specific protein deposits called Lewy Bodies. These Lewy Bodies contain alpha-synuclein and you find them in the brain, the gut and the heart and these are organs people hadn’t looked at because no one made the connection that constipation or depression could be linked to the disease. It turns out that Parkinson’s is much more complicated than just a problem in one particular region of the brain.
The other reason for slow progress is that we don’t have really good models for the disease that are predictive for clinical outcomes. This is why probably many clinical trials in the neurodegenerative field have failed to date. Now we have human induced pluripotent stem cells (iPSCs) from people with Parkinson’s, and iPSC-derived neurons allow us to better model the disease in the lab, and understand its underlying mechanisms more deeply. The technology has now advanced so that the ability to differentiate these cells into nerve cells is better, so that you now have iPSC-derived neurons in a dish that are functionally active, and that act and behave like dopamine-producing neurons in the brain. This is an important advance.
Will this lead to a clinical trial?
That’s the idea, that’s our hope.
We are working with professor Dr. Deniz Kirik at the University of Lund in Sweden. He’s an expert in the field of viral vectors that can be used in humans – it’s a joint grant between us – and so what we learn from the human iPS cultures, he’ll transfer to an animal model and use his gene vector technology to see if we can see the same effects in vivo, in mice.
We are using a very special Parkinson’s mouse model – developed at UC San Francisco – that has the complete human genomic structure of the alpha-synuclein gene. If all goes well, we hope that ultimately we could be ready in a couple of years to think about preclinical testing and then clinical trials.
What are your hopes for the future?
My hope is that I can contribute to stopping disease progression in Parkinson’s. If we can develop a drug that can get rid of accumulated protein in someone’s brain that should stop the cells from dying. If someone has early onset PD and a slight tremor and minor walking problems, stopping the disease and having a low dose of dopamine therapy to control symptoms is almost a cure.
The next step is to develop better biomarkers to identify people at risk of developing Parkinson’s, so if you know someone is a few years away from developing symptoms, and you have the tools in place, you can start treatment early and stop the disease from kicking in, even before you clinically have symptoms.
Thinking about people who have been diagnosed with a disease, who are ten years into the disease, who already have side effects from the disease, it’s a little harder to think of regenerative medicine, using embryonic or iPSCs for this. I think that it will take longer to see results with this approach, but that’s the long-term hope for the future. There are many groups working in this space, which is critical to advance the field.
Why is Parkinson’s Awareness Month important?
It’s important because, while a lot of people know about the disease, there are also a lot of misconceptions about Parkinson’s.
Parkinson’s is confused with Alzheimer’s or dementia and cognitive problems, especially the fact that it’s more than just a gait and movement problem, that it affects many other parts of the body too.