Normally if you meet someone who has a mini-fridge filled with brains, your first thought is to call the police. But when that someone is Dr. Alysson Muotri, a professor at U.C. San Diego, your second thought is “do tell me more.”
Alysson is a researcher who is fascinated by the human brain. He is working on many levels to try and unlock its secrets and give us a deeper understanding of how our brains evolved and how they work.
One of the main focuses of his work is autism (he has a son on the autism spectrum) and he has found a way to see what is happening inside the cells affected by autism—work that is already leading to the possibility of new treatments.
As for those mini-brains in his lab? Those are brain organoids, clumps of neurons and other cells that resemble—on a rudimentary level—our brains. They are ideal tools for seeing how our brains are organized, how the different cells signal and interact with each other. He’s already sent some of these brain organoids into space.
Brain in space
Alysson talks about all of this, plus how our brains compare to those of Neanderthals, on the latest episode of our podcast, Talking ‘Bout (re)Generation.
MRI section of a brain affected by ALS with the front section of the brain highlighted
Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig’s disease, is a nasty disease that steadily attacks nerve cells in the brain and spinal cord. It’s pretty much always fatal within a few years. As if that wasn’t bad enough, ALS also can overlap with a condition called frontotemporal dementia (ALS/FTD). Together these conditions cause devastating symptoms of muscle weakness along with changes in memory, behavior and personality.
Now researchers at Cambridge University in the UK have managed to grow groups of cells called “mini-brains” that mimic ALS/FTD and could lead to new approaches to treating this deadly combination.
We have written about these mini-brains before. Basically, they are created, using the iPSC method, that takes skin or blood cells from a patient with a particular condition, in this case ALS/FTD, and turns them into the kind of nerve cells in the brain affected by the disease. Because they came from someone who had ALS/FTD they display many of the characteristics of the disease and this gives researchers a great tool to study the condition.
This kind of approach has been done before and given researchers a glimpse into what is happening in the brains of people with ALS/FTD. But in the past those cells were in a kind of clump, and it wasn’t possible to get enough nutrients to the cells in the middle of the clump for the mini-brain to survive for long.
What is different about the Cambridge team is that they were able to create these mini-brains using thin, slices of cells. That meant all the cells could get enough nutrients to survive a long time, giving the team a better model to understand what is happening in ALS/FTD.
In a news release, Dr András Lakatos, the senior author of the study, said: “Neurodegenerative diseases are very complex disorders that can affect many different cell types and how these cells interact at different times as the diseases progress.
“To come close to capturing this complexity, we need models that are more long-lived and replicate the composition of those human brain cell populations in which disturbances typically occur, and this is what our approach offers. Not only can we see what may happen early on in the disease – long before a patient might experience any symptoms – but we can also begin to see how the disturbances change over time in each cell.”
Thanks to these longer-lived cells the team were able to see changes in the mini-brains at a very early stage, including damage to DNA and cell stress, changes that affected other cells which play a role in muscle movements and behavior.
Because the cells developed using the iPSC method are from a patient with ALS/FTD, the researchers were able to use them to screen many different medications to see if any had potential as a therapy. They identified one, GSK2606414, that seemed to help in reducing the build-up of toxic proteins, reduced cell stress and the loss of nerve cells.
The team acknowledge that these results are promising but also preliminary and will require much more research to verify them.
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.
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.
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.
Stem Cell Image of the Week: Obesity-in-a-dish reveals mutations and abnormal function in nerve cells
Image shows two types of hypothalamic neurons (in magenta and cyan) that were derived from human induced pluripotent stem cells. Credit: Cedars-Sinai Board of Governors Regenerative Medicine Institute
Our stem cell image of the week looks like the work of a pre-historic cave dweller who got their hands on some DayGlo paint. But, in fact, it’s a fluorescence microscopy image of stem cell-derived brain cells from the lab of Dhruv Sareen, PhD, at Cedars-Sinai Medical Center. Sareen’s team is investigating the role of the brain in obesity. Since the brain is a not readily accessible organ, the team reprogrammed skin and blood cell samples from severely obese and normal weight individuals into induced pluripotent stem cells (iPSCs). These iPSCs were then matured into nerve cells found in the hypothalamus, an area of the brain that regulates hunger and other functions.
A comparative analysis showed that the nerve cells derived from the obese individuals had several genetic mutations and had an abnormal response to hormones that play a role in telling our brains that we are hungry or full. The Cedars-Sinai team is excited to use this obesity-in-a-dish system to further explore the underlying cellular changes that lead to excessive weight gain. Ultimately, these studies may reveal ways to combat the ever-growing obesity epidemic, as Dr. Sareen states in a press release:
“We are paving the way for personalized medicine, in which drugs could be customized for obese patients with different genetic backgrounds and disease statuses.”
Differences found in stem cells derived from male vs female.
Microscope picture of a colony of iPS cells. Credit: Vincent Pasque
Scientists at UCLA and KU Leuven University in Belgium carried out a study to better understand the molecular mechanisms that control the process of reprogramming adult cells back into the embryonic stem cell-like state of induced pluripotent stem cells (iPSCs). Previous studies have shown that female vs male embryonic stem cells have different patterns of gene regulation. So, in the current study, male and female cells were analyzed side-by-side during the reprogramming process. First author Victor Pasquale explained in a press release that the underlying differences stemmed from the sex chromosomes:
In a normal situation, one of the two X chromosomes in female cells is inactive. But when these cells are reprogrammed into iPS cells, the inactive X becomes active. So, the female iPS cells now have two active X chromosomes, while males have only one. Our results show that studying male and female cells separately is key to a better understanding of how iPS cells are made. And we really need to understand the process if we want to create better disease models and to help the millions of patients waiting for more effective treatments.”
Using mini-brains and CRISPR to study genetic linkage of schizophrenia, depression and bipolar disorder.
If you haven’t already picked up on a common thread in this week’s stories, this last entry should make it apparent: iPSC cells are the go-to method to gain insight in the underlying mechanisms of a wide range of biology topics. In this case, researchers at Brigham and Women’s Hospital at Harvard Medical School were interested in understanding how mutations in a gene called DISC1 were linked to several mental illnesses including schizophrenia, bipolar disorder and severe depression. While much has been gleaned from animal models, there’s limited knowledge of how DISC1 affects the development of the human brain.
The team used human iPSCs to grow cerebral organoids, also called mini-brains, which are three-dimensional balls of cells that mimic particular parts of the brain’s anatomy. Using CRISPR-Cas9 gene-editing technology – another very popular research tool – the team introduced DISC1 mutations found in families suffering from these mental disorders.
Compared to cells with normal copies of the DISC1 gene, the mutant organoids showed abnormal structure and excessive cell signaling. When an inhibitor of that cell signaling was added to the growing mutant organoids, the irregular structures did not develop.
These studies using human cells provide an important system for gaining a better understanding of, and potentially treating, mental illnesses that victimize generations of families.
Growing neurons on a flat petri dish is a great way to study the inner workings of nerve signals in the brain. But I think it’s safe to argue that a two-dimensional lawn of cells doesn’t capture all the complexity of our intricate, cauliflower-shaped brains. Then again, cracking open the skulls of living patients is also not a viable path for fully understanding the molecular basis of brain disorders.
Brain organoids (two white balls) growing in petri dish. Image: Pasca Lab, Stanford University.
The recent emergence of stem cell-derived mini-brains, or brain organoids, as a research tool is bridging this impasse. With induced pluripotent stem cells (iPSCs) derived from a readily-accessible skin sample from patients, it’s possible to generate three-dimensional balls of cells that mimic particular parts of the brain’s anatomy. These mini-brains have the expected type of neurons, as well as other cells that support neuron function. We’ve written many blogs, most recently in January, on the applications of this cutting-edge tool.
With any new technology, there is always room for improvement. One thing that most mini-brains lack is their own system of blood vessels, or vasculature. That’s where Dr. Ben Waldau, a vascular neurosurgeon at UC Davis Medical Center, and his lab come into the picture. Last week, their published work in NeuroReport showed that incorporating blood vessels into a brain organoid is possible.
A stained cross-section of a brain organoid showing that blood vessels (in red) have penetrated both the outer, more organized layers and the inner core. Image: UC Davis Institute for Regenerative Cures
Using iPSCs from one patient, the Waldau team separately generated brain organoids and blood vessels cells, also called endothelial cells. After growing each for about a month, the organoids were embedded in a gelatin containing the endothelial cells. In an excellent Wired article, writer Megan Molteni explains what happened next:
“After incubating for three weeks, they took a single organoid and transplanted it into a tiny cavity carefully carved into a mouse’s brain. Two weeks later the organoid was alive, well—and, critically, had grown capillaries that penetrated all the way to its inner layers.”
Every tissue relies on nutrients and oxygen from the blood. As Molteni suggests, being able to incorporate blood vessels and brain organoids from the same patient’s cells may make it possible to grow and study even more complex brain structures without the need of a mouse using fluidic pumps.
As Waldau explains in the Wired article, this vascularized brain organoid system also adds promise to the ultimate goal of repairing damaged brain tissue:
Ben Waldau
“The whole idea with these organoids is to one day be able to develop a brain structure the patient has lost made with the patient’s own cells. We see the injuries still there on the CT scans, but there’s nothing we can do. So many of them are left behind with permanent neural deficits—paralysis, numbness, weakness—even after surgery and physical therapy.”
Here are the stem cell stories that caught our eye this week.
Two research photos really caught my eye this week and they happened to be of the same thing – mini-brains. Also referred to as brain organoids, mini-brains are tiny balls of nervous tissue grown from stem cells in the lab. They allow scientists to model early brain development and study how disease affects brain cells. Another awesome thing about mini-brains is how cool they look under a microscope.
Mini Brains Part 1
Mini-brain grown in a culture dish. (Photo by Collin Edington and Iris Lee, MIT)
I discovered the first photo in a blog by Dr. Francis Collins, the Director of the National Institutes of Health. He was featuring one of the winning images from the 2017 Koch Institute Image Awards at MIT. The mini-brain photo was taken by researchers Collin Edington and Iris Lee and took over 12 hours to make. Talk about dedication!
Collins revealed that growing mini-brains from stem cells is just the tip of the iceberg for this MIT team. The researchers have plans to grow other types of mini-organs and eventually combine them to make a “human on a chip”. This multi-organ technology will be extremely valuable for studying complex diseases like Alzheimer’s and Parkinson’s, which affect multiple systems in the body.
Mini Brains Part 2
Mini-brain. (Photo by Robert Krencik and Jessy Van Asperen)
The second photo of mini-brains is from a study published this week in Stem Cell Reports by researchers at the Houston Methodist Research Institute. The team has developed a more efficient and effective method for growing mini-brains from stem cells. Typically, the process takes weeks to grow the organoids and months to mature those organoids to the point where they develop the specific cell types and structures found in the human brain.
The Houston team found that maturing different types of brain cells from pluripotent stem cells separately and then combining these mature cells together produced mini-brains that more accurately represented the complexity of the human brain. The trick was to add the brain’s support cells, called astrocytes, to the mini-brains. The astrocytes effectively “accelerated the connections of the surrounding neurons.”
The studies first author, Robert Krencik, explained in a news release,
“We always felt like what we were doing in the lab was not precisely modeling how the cells act within the human brain. So, for the first time, when we put these cells together systematically, they dramatically changed their morphological complexity, size and shape. They look like cells as you would see them within the human brain, so now we can study cells in the lab in a more natural environment.”
Their method also cuts down the time it takes to make mini-brains which will hugely benefit neuroscience researchers who have passed on using mini-brains in their studies because of the cost and time it takes to grow them. Krencik explained,
“Normally, growing these 3-D mini brains takes months and years to develop. We have new techniques to pre-mature the cells separately and then combine them, and we found that within a few weeks they’re able to form mature interactions with each other. So, the length of time to get to that endpoint for studies is dramatically reduced with our system.”
The team plans to use this method to make patient-specific mini-brains from induced pluripotent stem cells to gain new insights into how disease affects the brain. They also hope to translate their mini-brain system into clinical trials to help patients regenerate brain damage or repair brain function.
This week we bring you three separate stories about the brain. Two are exciting new advances that use stem cells to understand the brain and the third is plain creepy.
Bioengineering better brains. Lab grown mini-brains got an upgrade thanks to a study published this week in Nature Biotechnology. Mini-brains are tiny 3D organs that harbor similar cell types and structures found in the human brain. They are made from pluripotent stem cells cultured in laboratory bioreactors that allow these cells to mature into brain tissue in the span of a month.
The brain organoid technology was first published back in 2013 by Austrian scientists Jürgen Knoblich and Madeline Lancaster. They used mini-brains to study human brain development and a model a birth defect called microcephaly, which causes abnormally small heads in babies. Mini-brains filled a void for scientists desperate for better, more relevant models of human brain development. But the technology had issues with consistency and produced organoids that varied in size, structure and cell type.
Cross-section of a mini-brain. (Madeline Lancaster/MRC-LMB)
Fast forward four years and the same team of scientists has improved upon their original method by adding a bioengineering technique that will generate more consistent mini-brains. Instead of relying on the stem cells to organize themselves into the proper structures in the brain, the team developed a biological scaffold made of microfilaments that guides the growth and development of stem cells into organoids. They called these “engineered cerebral organoids” or enCORs for short.
In a news feature on IMBA, Jürgen Knoblich explained that enCORs are more reproducible and representative of the brain’s architecture, thus making them more effective models for neurological and neurodevelopmental disorders.
“An important hallmark of the bioengineered organoids is their increased surface to volume ratio. Because of their improved tissue architecture, enCORs can allow for the study of a broader array of neurological diseases where neuronal positioning is thought to be affected, including lissencephaly (smooth brain), epilepsy, and even autism and schizophrenia.”
Salk team finds genetic links between brain’s immune cells and neurological disorders. (Todd Dubnicoff)
Dysfunction of brain cells called microglia have been implicated in a wide range of neurologic disorders like Alzheimer’s, Parkinson’s, Huntington’s, autism and schizophrenia. But a detailed examination of these cells has proved difficult because they don’t grow well in lab dishes. And attempts to grow microglia from stem cells is hampered by the fact that the cell type hasn’t been characterized enough for researchers to know how to distinguish it from related cell types found in the blood.
By performing an extensive analysis of microglia gene activity, Salk Institute scientists have now pinpointed genetic links between these cells and neurological disease. These discoveries also demonstrate the importance of the microglia’s environment within the brain to maintain its identity. The study results were reported in Science.
Microglia are important immune cells in the brain. They are related to macrophages which are white blood cells that roam through the body via the circulatory system and gobble up damaged or dying cells as well as foreign invaders. Microglia also perform those duties in the brain and use their eating function to trim away faulty or damage nerve connections.
To study a direct source of microglia, the team worked with neurosurgeons to obtain small samples of brain tissue from patients undergoing surgery for epilepsy, a tumor or stroke. Microglia were isolated from healthy regions of brain tissue that were incidentally removed along with damaged or diseased brain tissue.
Salk and UC San Diego scientists conducted a vast survey of microglia (pictured here), revealing links to neurodegenerative diseases and psychiatric illnesses. (Image: Nicole Coufal)
A portion of the isolated microglia were immediately processed to take a snap shot of gene activity. The researchers found that hundreds of genes in the microglia had much higher activities compared to those same genes in macrophages. But when the microglia were transferred to petri dishes, gene activity in general dropped. In fact, within six hours of tissue collection, the activity of over 2000 genes in the cells had dropped significantly. This result suggests the microglial rely on signals in the brain to stimulate their gene activity and may explain why they don’t grow well once removed from that environment into lab dishes.
Of the hundreds of genes whose activity were boosted in microglia, the researchers tracked down several that were linked to several neurological disorders. Dr. Nicole Coufal summarized these results and their implications in a Salk press release:
“A really high proportion of genes linked to multiple sclerosis, Parkinson’s and schizophrenia are much more highly expressed in microglia than the rest of the brain. That suggests there’s some kind of link between microglia and the diseases.”
Future studies are needed to explain the exact nature of this link. But with these molecular descriptions of microglia gene activity now in hand, the researchers are in a better position to study microglia’s role in disease.
A stem cell trial to bring back the dead, brain-dead that is. A somewhat creepy stem cell story resurfaced in the news this week. A company called Bioquark in Philadelphia is attempting to bring brain-dead patients back to life by injecting adult stem cells into their spinal cords in combination with other treatments that include protein blend injections, electrical nerve stimulation and laser therapy. The hope is that this combination stem cell therapy will generate new neurons that can reestablish lost connections in the brain and bring it back to life.
Abstract image of a neuron. (Dom Smith/STAT)
You might wonder why the company is trying multiple different treatments simultaneously. In a conversation with STAT news, Bioquark CEO Ira Pastor explained,
“It’s our contention that there’s no single magic bullet for this, so to start with a single magic bullet makes no sense. Hence why we have to take a different approach.”
Bioquark is planning to relaunch a clinical trial testing its combination therapy in Latin America sometime this year. The company previously attempted to launch its first trial in India back in April of 2016, but it never got off the ground because it failed to get clearance from India’s Drug Controller General.
STATnews staff writer Kate Sheridan called the trial “controversial” and raised questions about how it would impact patients and their families.
“How do researchers complete trial paperwork when the person participating is, legally, dead? If the person did regain brain activity, what kind of functional abilities would he or she have? Are families getting their hopes up for an incredibly long-shot cure?”
Scientists also have questions mainly about whether this treatment will actually work or is just a shot in the dark. Adding to the uncertainty is the fact that Bioquark has no preclinical evidence that its combination treatment is effective in animal models. The STAT piece details how the treatments have been tested individually for other conditions such as stroke and coma, but not in brain-dead patients. To further complicate things, there is no consensus on how to define brain death in patients, so patient improvements observed during the trial could be unrelated to the treatment.
STAT asked expert doctors in the field whether Bioquark’s strategy was feasible. Orthopedic surgeon Dr. Ed Cooper said that there’s no way electric stimulation would work, pointing out that the technique requires a functioning brain stem which brain-dead patients don’t have. Pediatric surgeon Dr. Charles Cox, who works on a stem cell treatment for traumatic brain injury and is unrelated to Bioquark, commented, “it’s not the absolute craziest thing I’ve ever heard, but I think the probability of that working is next to zero.”
But Pastor seems immune to the skepticism and naysayers.
“I give us a pretty good chance. I just think it’s a matter of putting it all together and getting the right people and the right minds on it.”
April is National Autism Awareness Month and people and organizations around the world are raising awareness about a disorder that affects more than 20 million people globally. Autism affects early brain development and causes a wide spectrum of social, mental, physical and emotional symptoms that appear during childhood. Because the symptoms and their severity can vary extremely between people, scientists now use the classification of autism spectrum disorder (ASM).
Alysson Muotri UC San Diego
In celebration of Autism Awareness Month, we’re featuring an interview with a CIRM-funded scientist who is on the forefront of autism and ASD research. Dr. Alysson Muotri is a professor at UC San Diego and his lab is interested in unlocking the secrets to brain development by using molecular tools and stem cell models.
One of his main research projects is on autism. Scientists in his lab are using induced pluripotent stem cells (iPSCs) derived from individuals with ASD to model the disease in a dish. From these stem cell models, his team is identifying genes that are associated with ASD and potential drugs that could be used to treat this disorder. Ultimately, Dr. Muotri’s goal is to pave a path for the development of personalized therapies for people with ASD.
I reached out to Dr. Muotri to ask for an update on his Autism research. His responses are below.
Q: Can you briefly summarize your lab’s work on Autism Spectrum Disorders?
AM: As a neuroscientist studying autism, I was frustrated with the lack of a good experimental model to understand autism. All the previous models (animal, postmortem brain tissues, etc.) have serious experimental limitations. The inaccessibility of the human brain has blocked the progress of research on ASD for a long time. Cellular reprogramming allows us to transform easy-access cell types (such as skin, blood, dental pulp, etc.) into brain cells or even “mini-brains” in the lab. Because we can capture the entire genome of the person, we can recapitulate early stages of neurodevelopment of that same individual. This is crucial to study neurodevelopment disorders, such as ASD, because of the strong genetic factor underlying the pathology [the cause of a disease]. By comparing “mini-brains” between an ASD and neurotypical [non-ASD] groups, we can find anatomical and functional differences that might explain the clinical symptoms.
Q: What types of tools and models are you using to study ASD?
AM: Most of my lab takes advantage of reprogramming stem cells and genome editing techniques to generate 3D organoid models of ASD. We use the stem cells to create brain organoids, also called “mini-brains” in the lab. These mini-brains will develop from single cells and grow and mature in the same way as the fetal brain. Thus, we can learn about their structure and connectivity over time.
A cross section of a cerebral organoid or mini-brain courtesy of Alysson Muotri.
This new model brings something novel to the table: the ability to experimentally test specific hypotheses in a human background. For example, we can ask if a specific genetic variant is causal for an autistic individual. Thus, we can edit the genome of that autistic individual, fixing target mutations in these mini-brains and check if now the fixed mini-brains will develop any abnormalities seen in ASD.
The ability to combine all these recent technologies to create a human experimental model of ASD in the lab is quite new and very exciting. As with any other model, there are limitations. For example, the mini-brains don’t have all the complexity and cell types seen in the developing human embryo/fetus. We also don’t know exactly if we are giving them the right and necessary environment (nutrients, growth factors, etc.) to mature. Nonetheless, the progress in this field is taking off quickly and it is all very promising.
Two mini-brains grown in a culture dish send out cellular extensions to connect with each other. Neurons are in green and astrocytes are in pink. Image courtesy of Dr. Muotri.
Q: We’ve previously written about your lab’s work on the Tooth Fairy Project and how you identified the TRPC6 gene. Can you share updates on this project and any new insights?
AM: The Tooth Fairy Project was designed to collect dental pulp cells from ASD and control individuals in a non-invasive fashion (no need for skin biopsy or to draw blood). We used social media to connect with families and engage them in our research. It was so successful we have now hundreds of cells in the lab. We use this material to reprogram into stem cells and to sequence their DNA.
One of the first ASD participants had a mutation in one copy of the TRPC6 gene, a novel ASD gene candidate. Everybody has two copies of this gene in the genome, but because of the mutation, this autistic kid has only one functional copy. Using stem cells, we re-created cortical neurons from that individual and confirmed that this mutation inhibits the formation of excitatory synapses (connections required to propagate information).
Interestingly, while studying TRPC6, we realized that a molecule found in Saint John’s Wort, hyperforin, could stimulate the functional TRPC6. Since the individual still has one functional TRPC6 gene copy, it seemed reasonable to test if hyperforin treatment could compensate the mutation on the other copy. It did. A treatment with hyperforin for only two weeks could revert the deficits on the neurons derived from that autistic boy. More exciting is the fact that the family agreed to incorporate St. John’s Wort on his diet. We have anecdotal evidence that this actually improved his social and emotional skills.
To me, this is the first example of personalized treatment for ASD, starting with genome sequencing, detecting potential causative genetic mutations, performing cellular modeling in the lab, and moving into clinic. I believe that there are many other autistic cases where this approach could be used to find better treatments, even with off the counter medications. To me, that is the greatest insight.
Watch Dr. Muotri’s Spotlight presentation about the Tooth Fairy Project and his work on autism.
Q: Is any of the research you are currently doing in autism moving towards clinical trials?
AM: IGF-1, or insulin growth factor-1, a drug we found promising for Rett syndrome and a subgroup of idiopathic [meaning its causes are spontaneous or unknown] ASD is now in clinical trials. Moreover, we just concluded a CIRM award on a large drug screening for ASD. The data is very promising, with several candidates. We have 14 drugs in the pipeline, some are repurposed drugs (initially designed for cancer, but might work for ASD). It will require additional pre-clinical studies before we start clinical trials.
Q: What do you think the future of diagnosis and treatment will be for patients with ASD?
AM: I am a big enthusiastic fan of personalized treatments for ASD. While we continue to search for a treatment that could help a large fraction of ASD people, we also recognized that some cases might be easier than others depending on their genetic profile. The idea of using stem cells to create “brain avatars” of ASD individuals in the lab is very exciting. We are also studying the possibility of using this approach as a future diagnostic tool for ASD. I can imagine every baby having their “brain avatar” analyses done in the lab, eventually pointing out “red flags” on the ones that failed to achieve neurodevelopment milestones. If we could capture these cases, way before the autism symptoms onset, we could initiate early treatments and therapies, increasing the chances for a better prognostic and clinical trajectory. None of these would be possible without stem cell research.
Q: What other types of research is your lab doing?
Mini-brains grown in a dish in Dr. Muotri’s lab.
AM: My lab is also using these human mini-brains to test the impact of environmental factors in neurodevelopment. By exposing the mini-brains to certain agents, such as pollution particles, household chemicals, cosmetics or agrotoxic products [pesticides], we can measure the concentration that is likely to induce brain abnormalities (defects in neuronal migration, synaptogenesis, etc.). This toxicological test can complement or substitute for other commonly used analyses, such as animal models, that are not very humane or predictive of human biology. A nice example from my lab was when we used this approach to confirm the detrimental effect of the Zika virus on brain development. Not only did we show causation between the circulating Brazilian Zika virus and microcephaly [a birth defect that causes an abnormally small head], but our data also pointed towards a potential mechanism (we showed that the virus kills neural progenitor cells, reducing the thickness of the cortical layers in the brain).
You can learn more about Dr. Muotri’s research on his lab’s website.
The Stem Cellar 