City of Hope scientists use stem cells to develop ‘mini-brains’ to study Alzheimer’s and to test drugs in development

Alzheimer’s is a progressive disease that destroys memory and other important mental functions. According to the non-profit HFC, co-founded by CIRM Board member Lauren Miller Rogen and her husband Seth Rogen, more than 5 million Americans are living with Alzheimer’s. It is the 6th leading cause of death in the U.S and it is estimated that by 2050 as many as 16 million Americans will have the disease. Alzheimer’s is the only cause of death among the top 10 in the U.S. without a way to prevent, cure, or even slow its progression, which is it is crucial to better understand the disease and to develop and test potential treatments.

It is precisely for this reason that researchers led by Yanhong Shi, Ph.D. at City of Hope have developed a ‘mini-brain’ model using stem cells in order to study Alzheimer’s and to test drugs in development.

The team was able to model sporadic Alzheimer’s, the most common form of the disease, by using human induced pluripotent stem cells (iPSCs), a kind of stem cell that can be created from skin or blood cells of people through reprogramming and has the ability to turn into virtually any other kind of cell. The researchers used these iPSCs to create ‘mini-brains’, also known as brain organoids, which are 3D models that can be used to analyze certain features of the human brain. Although they are far from perfect replicas, they can be used to study physical structure and other characteristics. 

The scientists exposed the ‘mini-brains’ to serum that mimics age-associated blood-brain barrier (BBB) breakdown. The BBB is a protective barrier that surrounds the brain and its breakdown has been associated with Alzheimer’s and other age-related neurodegenerative diseases . After exposure, the team tested the ‘mini-brains’ for various Alzheimer’s biomarkers. These markers included elevated levels of proteins known as amyloid and tau that are associated with the disease and synaptic breaks linked to cognitive decline.

Research using brain organoids has shown that exposure to serum from blood could induce multiple Alzheimer’s symptoms. This suggests that combination therapies targeting multiple areas would be more effective than single-target therapies currently in development.

The team found that attempting a single therapy, such as inhibiting only amyloid or tau proteins, did not reduce the levels of tau or amyloid, respectively. These findings suggest that amyloid and tau likely cause disease progression independently. Furthermore, exposure to serum from blood, which mimics BBB breakdown, could cause breaks in synaptic connections that help brains remember things and function properly.

Image Description: Yanhong Shi, Ph.D.

In a press release from the Associated Press, Dr. Shi elaborated on the importance of their model for studying Alzheimer’s.

“Drug development for Alzheimer’s disease has run into challenges due to incomplete understanding of the disease’s pathological mechanisms. Preclinical research in this arena predominantly uses animal models, but there is a huge difference between humans and animals such as rodents, especially when it comes to brain architecture. We, at City of Hope, have created a miniature brain model that uses human stem cell technology to study Alzheimer’s disease and, hopefully, to help find treatments for this devastating illness.”

The full results of this study were published in Advance Science.

Dr. Shi has previously worked on several CIRM-funded research projects, such as looking at a potential link between COVID-19 and a gene for Alzheimer’s as well as the development of a therapy for Canavan disease.

Scientists use stem cell ‘mini-brains’ to better understand signs of frontotemporal dementia

Dementia is a general term that describes a set of diseases that impair the ability to remember, think, or make decisions that interfere with doing everyday activities. According to the World Health Organization (WHO), around 50 million people worldwide have dementia with nearly 10 million new cases every year. Although it primarily affects older people it is not a normal part of aging. As our population ages its critical to better understand why this occurs.

Frontotemporal dementia is a rare form of dementia where people start to show signs between the ages of 40 and 60. It affects the front and side (temporal) areas of the brain, hence the name. It leads to behavior changes and difficulty with speaking and thinking. This form of the disease is caused by a genetic mutation called tau, which is known to be associated with Alzheimer’s disease and other dementias.

A CIRM supported study using induced pluripotent stem cells (iPSCs) led by Kathryn Bowles, Ph.D. and conducted by a team of researchers at Mount Sinai were able to recreate much of the damage seen in a widely studied form of the frontotemporal dementia by growing special types of ‘mini-brains’, also known as cerebral organoids.

iPSCs are a kind of stem cell that can be created from skin or blood cells through reprogramming and have the ability to turn into virtually any other kind of cell. The team used iPSCs to create thousands of tiny, 3D ‘mini-brains’, which mimic the early growth and development of the brain.

The researchers examined the growth and development of these ‘mini-brains’ using stem cells derived from three patients, all of whom carried a mutation in tau. They then compared their results with those observed in “normal” mini-brains which were derived from patient stem cells in which the disease-causing mutation was genetically corrected.

After six months, signs of neurodegeneration were seen in the patient ‘mini-brains’. The patient-derived ‘mini-brains’ had fewer excitatory neurons compared to the “normal” ones which demonstrates that the tau mutation was sufficient to cause higher levels of cell death of this specific class of neurons. Additionally, the patient-derived ‘mini-brains’ also had higher levels of harmful versions of tau protein and elevated levels of inflammation.

In a news release from Mount Sinai, Dr. Bowles elaborated on the results of this study.

“Our results suggest that the V337M mutant tau sets off a vicious cycle in the brain that puts excitatory neurons under great stress. It hastens the production of new proteins needed for maturation but prevents disposal of the proteins that are being replaced.”

The full results of this study were published in Cell.

UCSD researchers use stem cell model to better understand pregnancy complication

A team of UC San Diego researchers recently published novel preeclampsia models to aid in understanding this pregnancy complication that occurs in one of 25 U.S. pregnancies. Researchers include (left to right): Ojeni Touma, Mariko Horii, Robert Morey and Tony Bui. Credit: UC San Diego

Pregnant women often tread uncertain waters in regards to their health and well-being as well as that of their babies. Many conditions can arise and one of these is preeclampsia, a type of pregnancy complication that occurs in approximately one in 25 pregnancies in the United States according to the Center for Disease Control (CDC). It occurs when expecting mothers develop high blood pressure, typically after 20 weeks of pregnancy, and that in turn reduces the blood supply to the baby. This can lead to serious, even fatal, complications for both the mother and baby.

A CIRM supported study using induced pluripotent stem cells (iPSCs), a kind of stem cell that can turn into virtually any cell type, was able to create a “disease in a dish” model in order to better understand preeclampsia.

Credit: UC San Diego

For this study, Mariko Horii, M.D., and her team of researchers at the UC San Diego School of Medicine obtained cells from the placenta of babies born under preeclampsia conditions. These cells were then “reprogrammed” into a stem cell-like state, otherwise known as iPSCs. The iPSCs were then turned into cells resembling placental cells in early pregnancy. This enabled the team to create the preeclampsia “disease in the dish” model. Using this model, they were then able to study the processes that cause, result from, or are otherwise associated with preeclampsia.

The findings revealed that cellular defects observed are related to an abnormal response in the environment in the womb. Specifically, they found that preeclampsia was associated with a low-oxygen environment in the uterus. The researchers used a computer modeling system at UC San Diego known as Comet to detail the differences between normal and preeclampsia placental tissue.

Horii and her team hope that these findings not only shed more light on the environment in the womb observed in preeclampsia, but also provided insight for future development of diagnostic tools and identification of potential medications. Furthermore, they hope that their iPSC disease model can be used to study other placenta-associated pregnancy disorders such as fetal growth restriction, miscarriage, and preterm birth.

The team’s next steps are to develop a 3D model to better study the relationship between environment and development of placental disease.

In a news release from UC San Diego, Horri elaborates more on these future goals.

“Currently, model systems are in two-dimensional cultures with single-cell types, which are hard to study as the placenta consists of maternal and fetal cells with multiple cell types, such as placental cells (fetal origin), maternal immune cells and maternal endometrial cells. Combining these cell types together into a three-dimensional structure will lead to a better understanding of the more complex interactions and cell-to-cell signaling, which can then be applied to the disease setting to further understand pathophysiology.”

The full study was published in Scientific Reports.

Stem cell treatment improves motor function in monkeys modeling Parkinson’s Disease

Neurodegenerative diseases impact millions of people worldwide with the risk of being affected by one of these diseases increasing as you get older. For many of these diseases, there are very few treatments available to patients. As life expectancy increases and the population continues to age, it is crucial to try and find treatments that can potentially slow the progression of these diseases or cure them entirely. This is one of the reasons why CIRM has committed directing around $1.5 billion in funding over the next few years to research related to neurological disorders.

One of the most common neurodegenerative diseases is Parkinson’s Disease (PD), a movement disorder that affects one million people in the U.S alone and leads to shaking, stiffness, insomnia, fatigue, and problems with walking, balance, and coordination.  It is caused by the breakdown and death of dopaminergic neurons, special nerve cells in the brain responsible for the production of dopamine, a chemical messenger that is crucial for normal brain activity.

A recent study published in Nature Medicine has shown improved motor function and growth of neurons over a two year period in monkeys modeling PD. The study was conducted by Su-Chun Zhang, M.D., Ph.D. and his team at the University of Wisconsin using induced pluripotent stem cells (iPSCs), a kind of stem cell that can become virtually any type of cell that can be made from skin cells. The hope is that these results can pave the way for starting human clinical trials.

In order to replicate PD in humans, the team injected 10 adult monkeys with a neurotoxin that produces PD like symptoms. As a result of this, all 10 monkeys developed slow movements, imbalances, tremors, and impaired coordination in the hand on the opposite side of the injection. Additionally, scans revealed that on the injected side, monkeys lost most brain activity involving dopamine in two key brain areas. The team then waited three years after injecting the neurotoxin before administering the therapy, during which time the monkeys’ symptoms persisted.

To generate iPSC lines, the team obtained skin cells from five of the monkeys. The iPSCs were then turned into dopamine neural progenitor cells, which have the ability to create dopamine. These newly created cells were then administered into the brains of the five monkeys, with each monkey receiving a treatment derived from their own skin cells. A sixth iPSC line from a donor monkey was used for the remaining five monkeys to see how the treatment would work if it was not derived from their own skin cells.

The results showed that the monkeys that received the treatment derived from their own skin cells recovered. These animals moved more, moved faster, and were nimbler than before the treatment. They gained the ability to grasp treats, use all four limbs for walking, and climb their cages with ease and increased agility. However, the monkeys that received iPSCs derived from a donor did not recover. Their symptoms remained unchanged or worsened compared to before the treatment.

In a news article, Zhang emphasizes how he and his team are proceeding with a treatment derived from one’s own cells (autologous) vs. one from a donor (allogeneic).

“I initially wanted to do allogeneic transplants in patients because the autologous approach is too expensive. However, after seeing [our] data, I changed my mind. I want to go with the autologous first… because I feel the chance of success is really, really high.”

CIRM is currently funding a human clinical trial ($5.5 million) that is using a gene therapy approach for PD.

Friday Round Up

Here’s a look at a couple of stories that caught our eye this week:

Jasper Therapeutics has had a busy couple of weeks. Recently they announced data from their Phase 1 clinical trial treating people with Myelodysplastic syndromes (MDS). This is a group of disorders in which immature blood-forming cells in the bone marrow become abnormal and leads to low numbers of normal blood cells, especially red blood cells. We blogged about that here.

The data showed that six patients were given JSP191 – in combination with low-dose radiation five of the six had no detectable levels of disease and the sixth patient had reduced levels.

This was a big deal for us because CIRM funded the early stage research and even a clinical trial  that led to the development of JSP191.

Now Jasper has announced it is partnering with the National Institute of Allergy and Infectious Disease in a Phase 1/2 clinical trial using JSP191, as part of a treatment for chronic granulomatous disease (CGD). Congratulations to Jasper. And congratulations to us for helping them get there.

Oh, and just to toot our horn a little bit more – it is Friday after all – we have funded other approaches to CGD including one that resulted in curing Brenden Whittaker.

OK, enough about us.

To say that this last year has been a stressful one would be something of an understatement. But it’s not just people who get stressed. Stem cells do too. And, like people, when stem cells get stressed they don’t always behave in the way you would like them to. When some people get stressed they find a cocktail can help take the edge of it. Apparently that works for stem cells as well!

Now we are not talking about slipping a Manhattan or Mai Tai into a petri dish filled with stem cells. We are talking about a very different kind of cocktail.

Researchers at the National Institutes of Health have developed what they describe as a “four-part small molecule cocktail” that can help protect a specific kind of stem cell from stress. The cell is an induced pluripotent stem cell (iPSC), which has the ability to turn into any other kind of cell in the body. iPSC’s have great potential for treating a variety of different diseases and conditions, but they’re also sensitive and without the right conditions and environment they can get stressed and that in turn can damage their DNA and lead to them dying.

In a news release Dr. Ilyas Singeç, the lead researcher, says this NIH “cocktail” could help prevent that: “The small-molecule cocktail is safeguarding cells and making stem cell use more predictable and efficient. In preventing cellular stress and DNA damage that typically occur, we’re avoiding cell death and improving the quality of surviving cells. The cocktail will become a broadly used staple of the stem cell field and boost stem cell applications in both research and the clinic.”  

The team hope this could enhance the potential therapeutic uses of iPSCs in finding treatments for diseases such as diabetes, Parkinson’s and spinal cord injury.

The study is published in the journal Nature Methods.

CIRM funded study uses drug development in a dish for treatment of heart arrhythmias

Image Credit: Center for Disease Control and Prevention (CDC)

Cardiac (heart) arrhythmias occur when electrical impulses that coordinate your heartbeats don’t work properly, causing your heart to beat too fast, too slow, or in an irregular manner. In the U.S. alone, almost one million individuals are hospitalized every year for heart arrhythmias. Close to 300,000 individuals die of sudden arrhythmic death syndrome every year, which occurs when there is a sudden loss of blood flow resulting from the failure of the heart to pump effectively. Unfortunately, drugs to treat arrhythmias have liabilities and several drugs have been pulled from the market due to serious side effects. Mexiletine is one potential drug for heart arrhythmias that has liabilities and potential side effects.

That is why a CIRM funded study ($6.3 million) conducted by John Cashman, Ph.D. at the Human BioMolecular Research Institute in San Diego looked at re-engineering mexiletine in a way that the drug could still produce a desired result and not be as toxic.

The study used induced pluripotent stem cells (iPSCs), a type of stem cell “reprogrammed” from the skin or blood of patients that can be used to make virtually any kind of cell. iPSCs obtained for the study were from a healthy patient and from one with a type of heart arrhythmia. The healthy and arrhythmia iPSCs were then converted into cardiomyocytes, a type of cell that makes up the heart muscle.

By using their newly created healthy cardiomyocytes and those with the arrhythmia defect, Cashman and his team were able to carry out drug development in a dish. This enabled them to attempt to lessen drug toxicity while still potentially treating heart arrhythmias. The team was able to modify mexiletine such that is was less toxic and found that it could potentially decrease a patient’s risk of developing ventricular tachycardia (a fast, abnormal heart rate) and ventricular fibrillation (an abnormal heart rhythm), both of which are types of heart arrhythmias.

“The new compounds may lead to treatment applications in a whole host of cardiovascular conditions that may prove efficacious in clinical trials,” said Cashman in a press release. “As antiarrhythmic drug candidate drug development progresses, we expect the new analogs to be less toxic than current therapeutics for arrhythmia in congenital heart disease, and patients will benefit from improved safety, less side effects and possibly with significant cost-savings.”

The team hopes that their study can pave the way for future research in which cells in a dish can be used to lessen the toxicity of a potential drug candidate while still producing a desired result for different diseases and conditions.

The full study was published in ACS Publications.

CIRM funded researchers discover link between Alzheimer’s gene and COVID-19

Dr. Yanhong Shi (left) and Dr. Vaithilingaraja Arumugaswami (right)

All this month we are using our blog and social media to highlight a new chapter in CIRM’s life, thanks to the voters approving Proposition 14. We are looking back at what we have done since we were created in 2004, and also looking forward to the future. Today we focus on groundbreaking CIRM funded research related to COVID-19 that was recently published.

It’s been almost a year since the world started hearing about SARS-CoV-2, the virus that causes COVID-19.  In our minds, the pandemic has felt like an eternity, but scientists are still discovering new things about how the virus works and if genetics might play a role in the severity of the virus.  One population study found that people who have ApoE4, a gene type that has been found to increase the risk of developing Alzheimer’s, had higher rates of severe COVID-19 and hospitalizations.

It is this interesting observation that led to important findings of a study funded by two CIRM awards ($7.4M grant and $250K grant) and conducted by Dr. Yanhong Shi at City of Hope and co-led by Dr. Vaithilingaraja Arumugaswami, a member of the UCLA Broad Stem Cell Research Center.  The team found that the same gene that increases the risk for Alzheimer’s disease can increase the susceptibility and severity of COVID-19.

At the beginning of the study, the team was interested in the connection between SARS-CoV-2 and its effect on the brain.  Due to the fact that patients typically lose their sense of taste and smell, the team theorized that there was an underlying neurological effect of the virus.  

The team first created neurons and astrocytes.  Neurons are cells that function as the basic working unit of the brain and astrocytes provide support to them.  The neurons and astrocytes were generated from induced pluripotent stem cells (iPSCs), which are a kind of stem cell that can become virtually any type of cell and can be created by “reprogramming” the skin cells of patients.  The newly created neurons and astrocytes were then infected with SARS-CoV-2 and it was found that they were susceptible to infection.

Next, the team used iPSCs to create brain organoids, which are 3D models that mimic certain features of the human brain.  They were able to create two different organoid models: one that contained astrocytes and one without them.  They infected both brain organoid types with the virus and discovered that those with astrocytes boosted SARS-CoV-2 infection in the brain model. 

The team then decided to further study the effects of ApoE4 on susceptibility to SARS-CoV-2.  They did this by generating neurons from iPSCs “reprogrammed” from the cells of an Alzheimer’s patient.  Because the iPSCs were derived from an Alzheimer’s patient, they contained ApoE4.  Using gene editing, the team modified some of the ApoE4 iPSCs created so that they contained ApoE3, which is a gene type considered neutral.  The ApoE3 and ApoE4 iPSCs were then used to generate neurons and astrocytes.

The results were astounding.  The ApoE4 neurons and astrocytes both showed a higher susceptibility to SARS-CoV-2 infection in comparison to the ApoE3 neurons and astrocytes.  Moreover, while the virus caused damage to both ApoE3 and ApoE4 neurons, it appeared to have a slightly more severe effect on ApoE4 neurons and a much more severe effect on ApoE4 astrocytes compared to ApoE3 neurons and astrocytes. 

“Our study provides a causal link between the Alzheimer’s disease risk factor ApoE4 and COVID-19 and explains why some (e.g. ApoE4 carriers) but not all COVID-19 patients exhibit neurological manifestations” says Dr. Shi. “Understanding how risk factors for neurodegenerative diseases impact COVID-19 susceptibility and severity will help us to better cope with COVID-19 and its potential long-term effects in different patient populations.”

In the last part of the study, the researchers tested to see if the antiviral drug remdesivir inhibits virus infection in neurons and astrocytes.  They discovered that the drug was able to successfully reduce the viral level in astrocytes and prevent cell death.  For neurons, it was able to rescue them from steadily losing their function and even dying. 

The team says that the next steps to build on their findings is to continue studying the effects of the virus and better understand the role of ApoE4 in the brains of people who have COVID-19.  Many people that developed COVID-19 have recovered, but long-term neurological effects such as severe headaches are still being seen months after. 

“COVID-19 is a complex disease, and we are beginning to understand the risk factors involved in the manifestation of the severe form of the disease” says Dr. Arumugaswami.  “Our cell-based study provides possible explanation to why individuals with Alzheimer’s’ disease are at increased risk of developing COVID-19.”

The full results to this study were published in Cell Stem Cell.

“Mini-brains” model an autism spectrum disorder and help test treatments

Alysson Muotri, PhD, professor and director of the Stem Cell Program at UC San Diego School of Medicine
and member of the Sanford Consortium for Regenerative Medicine.
Image credit: UC San Diego Health

Rett syndrome is a rare form of autism spectrum disorder that impairs brain development and causes problems with movement, speech, and even breathing. It is caused by mutations in a gene called MECP2 and primarily affects females. Although there are therapies to alleviate symptoms, there is currently no cure for this genetic disorder.

With CIRM funding ($1.37M and $1.65M awards), Alysson Muotri, PhD and a team of researchers at the University of California San Diego School of Medicine and Sanford Consortium for Regenerative Medicine have used brain organoids that mimic Rett syndrome to identify two drug candidates that returned the “mini-brains” to near-normal. The drugs restored calcium levels, neurotransmitter production, and electrical impulse activity.

Brain organoids, also referred to as “mini-brains”, are 3D models made of cells that can be used to analyze certain features of the human brain. Although they are far from perfect replicas, they can be used to study changes in physical structure or gene expression over time.

Dr. Muotri and his team created induced pluripotent stem cells (iPSCs), a type of stem cell that can become virtually any type of cell. For the purposes of this study, they were created from the skin cells of Rett syndrome patients. The newly created iPSCs were then turned into brain cells and used to create “mini-brains”, thereby preserving each Rett syndrome patient’s genetic background. In addition to this, the team also created “mini-brains” that artificially lack the MECP2 gene, mimicking the issues with the same gene observed in Rett syndrome.

Lack of the MECP2 gene changed many things about the “mini-brains” such as shape, neuron subtypes present, gene expression patterns, neurotransmitter production, and decreases in calcium activity and electrical impulses. These changes led to major defects in the emergence of brainwaves.

To correct the changes caused by the lack of the MECP2 gene, the team treated the brain organoids with 14 different drug candidates known to affect various brain cell functions. Of all the drugs tested, two stood out: nefiracetam and PHA 543613. The two drugs resolved nearly all molecular and cellular symptoms observed in the Rett syndrome “mini-brains”, with the number active neurons doubling post treatment.

The two drugs were previously tested in clinical trials for the treatment of other conditions, meaning they have been shown to be safe for human consumption.

In a news release from UC San Diego Health, Dr. Muotri stresses that although the results for the two drugs are promising, the end treatment for Rett syndrome may require a multi-drug cocktail of sorts.

“There’s a tendency in the neuroscience field to look for highly specific drugs that hit exact targets, and to use a single drug for a complex disease. But we don’t do that for many other complex disorders, where multi-pronged treatments are used. Likewise, here no one target fixed all the problems. We need to start thinking in terms of drug cocktails, as have been successful in treating HIV and cancers.”

The full results of this study were published in EMBO Molecular Medicine.

CIRM-funded study discovers potential therapy for one of the leading causes of heart disease

Dr. Deepak Srivastava and his team found a drug candidate that could help prevent tens of thousands of heart surgeries every year. Image Credit: Gladstones Institute

According to the Center for Disease Control and Prevention (CDC), heart disease is the leading cause of death for men, women, and people of most racial and ethnic groups in the United States. About 655,000 Americans die from heart disease each year, which is about one in every four deaths.

Calcific aortic valve disease, the third leading cause of heart disease overall, occurs when calcium starts to accumulate in the heart valves and vessels over time, causing them to gradually harden like bone. This leads to obstruction of blood flow out of the heart’s pumping chamber, causing heart failure. Unfortunately there is no treatment for this condition, leaving patients only with the option of surgery to replace the heart valve once the hardening is severe enough.

But thanks to a CIRM-funded ($2.4 million) study conducted by Dr. Deepak Srivastava and his team at the Gladstone Institutes, a potential drug candidate for heart valve disease was discovered. It has been found to function in both human cells and animals and is ready to move toward a clinical trial.

For this study, Dr. Srivastava and his team looked for drug-like molecules that had the potential to correct the mechanism in heart valve disease that leads to gradual hardening. To do so, the team first had to determine the network of genes that are turned on or off in the diseased cells.

Once the genes were identified, they used an artificial intelligence method to train a machine learning program to detect whether a cell was healthy or diseased based on the network of genes identified. They proceeded to treat the diseased human cells with nearly 1,600 molecules in order to identify any drugs that would cause the machine learning program to reclassify diseased cells as healthy. The team successfully identified a few molecules that could correct diseased cells back to a healthy state.

Dr. Srivastara then collaborated with Dr. Anna Malashicheva, from the Russian Academy of Sciences, who had collected valve cells from over 20 patients at the time of surgical replacement. Using the valve cells that Dr. Malashicheva had collected, Dr. Srivastara and his team conducted a “clinical trial in a dish” in which they tested the molecules they had previously identified in the cells from the 20 patients with aortic valve hardening. The results were remarkable, as the molecule that seemed most effective in the initial study was able to restore these patients’ cells as well.

The final step taken was to determine whether the drug-like molecule would actually work in a whole, living organ. To do this, Dr. Srivastava and his team did a “pre-clinical trial” in a mouse model of the disease. The team found that the therapeutic candidate could successfully prevent and treat aortic valve disease. In young mice who had not yet developed the disease, the therapy prevented the hardening of the valve. In mice that already had the disease, the therapy was able to halt the disease and, in some cases, reverse it. This finding is especially important since most patients aren’t diagnosed until hardening of the heart valve has already begun.

Dr. Deepak Srivastava (left) and Dr. Christina V. Theodoris (right)
Image Credit: Gladstones Institute

Dr. Christina V. Theodoris, a lead author of the study who is now completing her residency in pediatric genetics, was a graduate student in Dr. Srivastava’s lab and played a critical role in this research. Her first project was to convert the cells from patient families into induced pluripotent stem cells (iPSCs), which have the potential of becoming any cell in the body. The newly created iPSCs were then turned into cells that line the valve, allowing the team to understand why the disease occurs. Her second project was to make a mouse model of calcific aortic valve disease, which enabled them to start using the models to identify a therapy.

In a press release from Gladstone Institutes, Dr. Theodoris, discusses the impact of the team’s research.

“Our strategy to identify gene network–correcting therapies that treat the core disease mechanism may represent a compelling path for drug discovery in a range of other human diseases. Many therapeutics found in the lab don’t translate well to humans or focus only on a specific symptom. We hope our approach can offer a new direction that could increase the likelihood of candidate therapies being effective in patients.”

In the same press release, Dr. Srivastava emphasizes the scientific advances that have driven the team’s research to this critical point.

“Our study is a really good example of how modern technologies are facilitating the kinds of discoveries that are possible today, but weren’t not so long ago. Using human iPSCs and gene editing allowed us to create a large number of cells that are relevant to the disease process, while powerful machine learning algorithms helped us identify, in a non-biased fashion, the important genes for distinguishing between healthy and diseased cells.”

The full results of this study were published in Science.

CIRM-funded development of stem cell therapy for Canavan disease shows promising results

Yanhong Shi, Ph.D., City of Hope

Canavan disease is a fatal neurological disorder, the most prevalent form of which begins in infancy. It is caused by mutation of the ASPA gene, resulting in the deterioration of white matter (myelin) in the brain and preventing the proper transmission of nerve signals.  The mutated ASPA gene causes the buildup of an amino acid called NAA and is typically found in neurons in the brain.  As a result of the NAA buildup, Canavan disease causes symptoms such as impaired motor function, mental retardation, and early death. Currently, there is no cure or standard of treatment for this condition.

Fortunately, CIRM-funded research conducted at City of Hope by Yanhong Shi, Ph.D. is developing a stem cell-based treatment for Canavan disease. The research is part of CIRM’s Translational Stage Research Program, which promotes the activities necessary for advancement to clinical study of a potential therapy.

The results from the study are promising, with the therapy improving motor function, reducing degeneration of various brain regions, and expanding lifespan in a Canavan disease mouse model.

For this study, induced pluripotent stem cells (iPSCs), which can turn into virtually any type of cells, were created from skin cells of Canavan disease patients. The newly created iPSCs were then used to create neural progenitor cells (NPCs), which have the ability to turn into various types of neural cells in the central nervous system. A functional version of the ASPA gene was then introduced into the NPCs. These newly created NPCs were then transplanted inside the brains of Canavan disease mice.

The study also used iPSCs engineered to have a functional version of the ASPA gene. The genetically modified iPSCs were then used to create oligodendrocyte progenitor cells (OPCs), which have the ability to turn into myelin. The OPCs were also transplanted inside the brains of mice.

The rationale for evaluating both NPCs and OPCs was that NPCs typically stayed at the site of injection while OPCs tend to migrate, which might have been important in terms of the effectiveness of the therapy.  However, the results of the study show that both NPCs and OPCs were effective, with both being able to reduce levels of NAA, presumably because NAA can move to where the ASPA enzyme is although NPCs do not migrate.  This resulted in improved motor function, recovery of myelin, and reduction of brain degeneration, in both the NPC and OPC-transplanted Canavan disease mice.

“Thanks to funding from CIRM and the hard work of my team here at City of Hope and collaborators at Center for Biomedicine and Genetics, Department of Molecular Imaging and Therapy, and Diabetes and Metabolism Institute at City of Hope, as well as collaborators from the University of Texas Medical Branch at Galveston, University of Rochester Medical Center, and Aarhus University, we were able to carry out this study which has demonstrated promising results,” said Dr. Shi.  “I hope that these findings can one day bring about an effective therapy for Canavan disease patients, who currently have no treatment options.”

Dr. Shi and her team will build on this research by starting IND-enabling studies using their NPC therapy soon.  This is the final step in securing approval from the Food and Drug Administration (FDA) in order to test the therapy in patients.  

The full study was published in Advanced Science.