Stem Cell Agency Invests in New Immunotherapy Approach to HIV, Plus Promising Projects Targeting Blindness and Leukemia

HIV AIDS

While we have made great progress in developing therapies that control the AIDS virus, HIV/AIDS remains a chronic condition and HIV medicines themselves can give rise to a new set of medical issues. That’s why the Board of the California Institute for Regenerative Medicine (CIRM) has awarded $3.8 million to a team from City of Hope to develop an HIV immunotherapy.

The City of Hope team, led by Xiuli Wang, is developing a chimeric antigen receptor T cell or CAR-T that will enable them to target and kill HIV Infection. These CAR-T cells are designed to respond to a vaccine to expand on demand to battle residual HIV as required.

Jeff Sheehy

CIRM Board member Jeff Sheehy

Jeff Sheehy, a CIRM Board member and patient advocate for HIV/AIDS, says there is a real need for a new approach.

“With 37 million people worldwide living with HIV, including one million Americans, a single treatment that cures is desperately needed.  An exciting feature of this approach is the way it is combined with the cytomegalovirus (CMV) vaccine. Making CAR T therapies safer and more efficient would not only help produce a new HIV treatment but would help with CAR T cancer therapies and could facilitate CAR T therapies for other diseases.”

This is a late stage pre-clinical program with a goal of developing the cell therapy and getting the data needed to apply to the Food and Drug Administration (FDA) for permission to start a clinical trial.

The Board also approved three projects under its Translation Research Program, this is promising research that is building on basic scientific studies to hopefully create new therapies.

  • $5.068 million to University of California at Los Angeles’ Steven Schwartz to use a patient’s own adult cells to develop a treatment for diseases of the retina that can lead to blindness
  • $4.17 million to Karin Gaensler at the University of California at San Francisco to use a leukemia patient’s own cells to develop a vaccine that will stimulate their immune system to attack and destroy leukemia stem cells
  • Almost $4.24 million to Stanford’s Ted Leng to develop an off-the-shelf treatment for age-related macular degeneration (AMD), the leading cause of vision loss in the elderly.

The Board also approved funding for seven projects in the Discovery Quest Program. The Quest program promotes the discovery of promising new stem cell-based technologies that will be ready to move to the next level, the translational category, within two years, with an ultimate goal of improving patient care.

Application Title Institution CIRM Committed Funding
DISC2-10979 Universal Pluripotent Liver Failure Therapy (UPLiFT)

 

Children’s Hospital of Los Angeles $1,297,512

 

DISC2-11105 Pluripotent stem cell-derived bladder epithelial progenitors for definitive cell replacement therapy of bladder cancer

 

Stanford $1,415,016
DISC2-10973 Small Molecule Proteostasis Regulators to Treat Photoreceptor Diseases

 

U.C. San Diego $1,160,648
DISC2-11070 Drug Development for Autism Spectrum Disorder Using Human Patient iPSCs

 

Scripps $1,827,576
DISC2-11183 A screen for drugs to protect against chemotherapy-induced hearing loss, using sensory hair cells derived by direct lineage reprogramming from hiPSCs

 

University of Southern California $833,971
DISC2-11199 Modulation of the Wnt pathway to restore inner ear function

 

Stanford $1,394,870
DISC2-11109 Regenerative Thymic Tissues as Curative Cell Therapy for Patients with 22q11 Deletion Syndrome

 

Stanford $1,415,016

Finally, the Board approved the Agency’s 2019 research budget. Given CIRM’s new partnership with the National Heart, Lung, Blood Institute (NHLBI) to accelerate promising therapies that could help people with Sickle Cell Disease (SCD) the Agency is proposing to set aside $30 million in funding for this program.

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Congresswoman Barbara Lee (D-CA 13th District)

“I am deeply grateful for organizations like CIRM and NHLBI that do vital work every day to help people struggling with Sickle Cell Disease,” said Congresswoman Barbara Lee (D-CA 13th District). “As a member of the House Appropriations Subcommittee on Labor, Health and Human Services, and Education, I know well the importance of this work. This innovative partnership between CIRM and NHLBI is an encouraging sign of progress, and I applaud both organizations for their tireless work to cure Sickle Cell Disease.”

Under the agreement CIRM and the NHLBI will coordinate efforts to identify and co-fund promising therapies targeting SCD.  Programs that are ready to start an IND-enabling or clinical trial project for sickle cell can apply to CIRM for funding from both agencies. CIRM will share application information with the NHLBI and CIRM’s Grants Working Group (GWG) – an independent panel of experts which reviews the scientific merits of applications – will review the applications and make recommendations. The NHLBI will then quickly decide if it wants to partner with CIRM on co-funding the project and if the CIRM governing Board approves the project for funding, the two organizations will agree on a cost-sharing partnership for the clinical trial. CIRM will then set the milestones and manage the single CIRM award and all monitoring of the project.

“This is an extraordinary opportunity to create a first-of-its-kind partnership with the NHLBI to accelerate the development of curative cell and gene treatments for patients suffering with Sickle Cell Disease” says Maria T. Millan, MD, President & CEO of CIRM. “This allows us to multiply the impact each dollar has to find relief for children and adults who battle with this life-threatening, disabling condition that results in a dramatically shortened lifespan.  We are pleased to be able to leverage CIRM’s acceleration model, expertise and infrastructure to partner with the NHLBI to find a cure for this condition that afflicts 100,000 Americans and millions around the globe.”

The budget for 2019 is:

Program type 2019
CLIN1 & 2

CLIN1& 2 Sickle Cell Disease

$93 million

$30 million

TRANSLATIONAL $20 million
DISCOVER $0
EDUCATION $600K

 

 

Stem Cell Roundup: Knowing the nose, stem cell stress and cell fate math.

The Stem Cellar’s Image of the Week.
Our favorite image this week, comes to us from researchers at Washington University School of Medicine in St. Louis. Looking like a psychedelic Rorschach test, the fluorescence microscopy depicts mouse olfactory epithelium (in green), a sheet of tissue that develops in the nose. The team identified a new stem cell type that controls the growth of this tissue. New insights from the study of these cells could help the team better understand why some animals, like dogs, have a far superior sense of smell than humans.

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Peering into the nasal cavity of a mouse. Olfactory epithelium is indicated by green. Image credit: Lu Yang, Washington University School of Medicine in St. Louis.

A Washington U. press release provides more details about this fascinating study which appears in Developmental Cell.

How stress affects blood-forming stem cells.
Stress affects all of us in different ways. Some people handle it well. Some crack up and become nervous wrecks. So, perhaps it shouldn’t come as a huge surprise that stress also affects some stem cells. What is a pleasant surprise is that knowing this could help people undergoing cancer therapy or bone marrow transplants.

First a bit of background. Hematopoietic, or blood-forming stem cells (HSCs) come from bone marrow and are supported by other cells that secrete growth factors, including one called pleiotrophin or PTN. While researchers knew PTN was present in bone marrow they weren’t sure precisely what role it played.

So, researchers at UCLA set out to discover what PTN did.

In a CIRM-funded study they took mice that lacked PTN in endothelial cells – these line the blood vessels – or in their stromal cells – which make up the connective tissue. They found that a lack of PTN in stromal cells caused a lack of blood stem cells, but a lack of PTN in endothelial cells had no impact.

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Expression of pleiotrophin (green) in bone marrow blood vessels (red) and stromal cells (white) is shown in normal mice (left) and in mice at 24 hours following irradiation (right). Image credit: UCLA

However, as Dr. John Chute explained in a news release, when they stressed the cells, by exposing them to radiation, they found something very different:

“The surprising finding was that pleiotrophin from stromal cells was not necessary for blood stem cell regeneration following irradiation — but pleiotrophin from endothelial cells was necessary.”

In other words, during normal times the stem cells rely on PTN from stromal cells, but after stress they depend on PTN from endothelial cells.

Dr. Chute says, because treatments like chemotherapy and radiation deplete bone marrow stem cells, this finding could have real-world implications for patients.

“These therapies for cancer patients suppress our blood cell systems over time. It may be possible to administer modified, recombinant versions of pleiotrophin to patients to accelerate blood cell regeneration. This strategy also may apply to patients undergoing bone marrow transplants.”

The study appears in the journal Cell Stem Cell.

Predicting the fate of cells with math
Researchers at Harvard Medical School and the Karolinska Institutet in Sweden reported this week that they have devised a mathematical model that can predict the fate of stem cells in the brain.

It may sound like science-fiction but the accomplished the feat by tracking changes in messenger RNA (mRNA), the genetic molecule that translates our DNA code into instructions for building proteins. As a brain stem cell begins specializing into specific cell types, hundreds of genes get turns on and off, which is observed by the rate of changes in mRNA productions.

The team built their predictive model by measuring these changes. In a press release, co-senior author, Harvard professor Peter Kharchenko, described this process using a great analogy:

“Estimating RNA velocity—or the rate of RNA change over time—is akin to observing the cooks in a restaurant kitchen as they line up the ingredients to figure out what dishes they’ll be serving up next.”

The team verified their mathematical model by inputting other data that was not use in constructing the model. Karolinkska Institutet professor, Sten Linnarsson, the other co-senior author on the study, described how such a model could be applied to human biomedical research:

“RNA velocity shows in detail how neurons and other cells acquire their specific functions as the brain develops and matures. We’re especially excited that this new method promises to help reveal how brains normally develop, but also to provide clues as to what goes wrong in human disorders of brain development, such as schizophrenia and autism.”

The study appears in the journal Nature.

Friday Stem Cell Roundup: Making Nerves from Blood; New Clues to Treating Parkinson’s

Stanford lab develops method to make nerve cells from blood.

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Induced neuronal (iN) cells derived from adult human blood cells. Credit: Marius Wernig, Stanford University.

Back in 2010, Stanford Professor Marius Wernig and his team devised a method to directly convert skin cells into neurons, a nerve cell. This so-called transdifferentiation technique leapfrogs over the need to first reprogram the skin cells into induced pluripotent stem cells. This breakthrough provided a more efficient path to studying how genetics plays a role in various mental disorders, like autism or schizophrenia, using patient-derived cells. But these types of genetic analyses require data from many patients and obtaining patient skin samples hampered progress because it’s not only an invasive, somewhat painful procedure but it also takes time and money to prepare the tissue sample for the transdifferentiation method.

This week, the Wernig lab reported on a solution to this bottleneck in the journal, PNAS. The study, funded in part by CIRM, describes a variation on their transdifferentiation method which converts T cells from the immune system, instead of skin cells, into neurons. The huge advantage with T cells is that they can be isolated from readily available blood samples, both fresh or frozen. In a press release, Wernig explains this unexpected but very welcomed result:

“It’s kind of shocking how simple it is to convert T cells into functional neurons in just a few days. T cells are very specialized immune cells with a simple round shape, so the rapid transformation is somewhat mind-boggling. We now have a way to directly study the neuronal function of, in principle, hundreds of people with schizophrenia and autism. For decades we’ve had very few clues about the origins of these disorders or how to treat them. Now we can start to answer so many questions.”

Two studies targeting Parkinson’s offer new clues to treating the disease (Kevin McCormack)
Despite decades of study, Parkinson’s disease remains something of a mystery. We know many of the symptoms – trembling hands and legs, stiff muscles – are triggered by the loss of dopamine producing cells in the brain, but we are not sure what causes those cells to die. Despite that lack of certainty researchers in Germany may have found a way to treat the disease.

Mitochondria

Simple diagram of a mitochondria.

They took skin cells from people with Parkinson’s and turned them into the kinds of nerve cell destroyed by the disease. They found the cells had defective mitochondria, which help produce energy for the cells. Then they added a form of vitamin B3, called nicotinamide, which helped create new, healthy mitochondria.

In an article in Science & Technology Research News Dr. Michela Deleidi, the lead researcher on the team, said this could offer new pathways to treat Parkinson’s:

“This substance stimulates the faulty energy metabolism in the affected nerve cells and protects them from dying off. Our results suggest that the loss of mitochondria does indeed play a significant role in the genesis of Parkinson’s disease. Administering nicotinamide riboside may be a new starting-point for treatment.”

The study is published in the journal Cell Reports.

While movement disorders are a well-recognized feature of Parkinson’s another problem people with the condition suffer is sleep disturbances. Many people with Parkinson’s have trouble falling asleep or remaining asleep resulting in insomnia and daytime sleepiness. Now researchers in Belgium may have uncovered the cause.

Working with fruit flies that had been genetically modified to have Parkinson’s symptoms, the researchers discovered problems with neuropeptidergic neurons, the type of brain cell that helps regulate sleep patterns. Those cells seemed to lack a lipid, a fat-like substance, called phosphatidylserine.

In a news release Jorge Valadas, one of the lead researchers, said replacing the missing lipid produced promising results:

“When we model Parkinson’s disease in fruit flies, we find that they have fragmented sleep patterns and difficulties in knowing when to go to sleep or when to wake up. But when we feed them phosphatidylserine–the lipid that is depleted in the neuropeptidergic neurons–we see an improvement in a matter of days.”

Next, the team wants to see if the same lipids are low in people with Parkinson’s and if they are, look into phosphatidylserine – which is already approved in supplement form – as a means to help ease sleep problems.

East Coast Company to Sell Research Products Derived from CIRM’s Stem Cell Bank

With patient-derived induced pluripotent stem cells (iPSCs) in hand, any lab scientist can follow recipes that convert these embryonic-like stem cells into specific cell types for studying human disease in a petri dish. iPSCs derived from a small skin sample from a Alzheimer’s patient, for instance, can be specialized into neurons – the kind of cell affected by the disease – to examine what goes wrong in an Alzheimer’s patient’s brain or screen drugs that may alleviate the problems.

exilirneurons

Neurons created from Alzheimer’s disease patient-derived iPSCs.
Image courtesy Elixirgen Scientific

But not every researcher has easy access to a bank of patient-derived iPSCs and it’s not trivial to coax iPSCs to become a particular cell type. The process is also a time sink and many scientists would rather spend that time doing what they’re good at: uncovering new insights into their disease of interest.

Since the discovery of iPSC technology over a decade ago, countless labs have worked out increasingly efficient variations on the original method. In fact, companies that deliver iPSC-derived products have emerged as an attractive option for the time-strapped stem cell researcher.

One of those companies is Elixirgen Scientific of Baltimore, Maryland. Pardon the pun but Elixirgen has turned the process of making various cell types from iPSCs into a science. Here’s how CEO Bumpei Noda described the company’s value to me:

Bumpei-Noda-200

Bumpei Noda

“Our technology directly changes stem cells into the cells that make up most of your body, such as muscle cells or neural cells, in about one week. Considering that existing technology takes multiple weeks or even months to do the same thing, imagine how much more research can get done than before.”

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With Elixirgen’s technology, different “cocktails” of ingredients can quickly and efficiently turn iPSCs into many different human cell types. Image courtesy Elixirgen Scientific

Their technology is set to become an even greater resource for researchers based on their announcement yesterday that they’ve signed a licensing agreement to sell human disease cells that were generated from CIRM’s iPSC Repository.

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Stephen Lin

“The CIRM Repository holds the largest publicly accessible collection of human iPSCs in the world and is the result of years of coordinated efforts of many groups to create a leading resource for disease modeling and drug discovery using stem cells,” said Stephen Lin, a CIRM Senior Science Officer who oversees the cell bank.

 

The repository currently contains a collection of 1,600 cell lines derived from patients with diseases that are a source of active research, including autism, epilepsy, cerebral palsy, Alzheimer’s disease, heart disease, lung disease, hepatitis C, fatty liver disease, and more (visit our iPSC Repository web page for the complete list).

While this wide variety of patient cells lines certainly played a major role in Elixirgen’s efforts to sign the agreement, Noda also noted that the CIRM Repository “has rich clinical and demographic data and age-matched control cell lines” which is key information to have when interpreting the results of experiments and drug screening.

Lin also points out another advantage to the CIRM cells:

“It’s one of the few collections with a streamlined route to commercialization (i.e. pre-negotiated licenses) that make activities like Elixirgen’s possible. iPSC technology is still under patent and technically cannot be used for drug discovery without those legal safeguards. That’s important because if you do discover a drug using iPSCs without taking care of these licensing agreements, your discovery could be owned by that original intellectual property holder.”

At CIRM, we’re laser-focused on accelerating stem cell treatments to patients with unmet medical needs. That’s why we’re excited that Elixirgen Scientific has licensed access to the our iPSC repository. We’re confident their service will help researchers work more efficiently and, in turn, accelerate the pace of new discoveries.

Modeling the Human Brain in 3D

(Image from Pasca Lab, Stanford University)

Can you guess what the tiny white balls are in this photo? I’ll give you a hint, they represent the organ that you’re using right now to answer my question.

These are 3D brain organoids generated from human pluripotent stem cells growing in a culture dish. You can think of them as miniature models of the human brain, containing many of the brain’s various cell types, structures, and regions.

Scientists are using brain organoids to study the development of the human nervous system and also to model neurological diseases and psychiatric disorders. These structures allow scientists to dissect the inner workings of the brain – something they can’t do with living patients.

Brain-in-a-Dish

Dr. Sergiu Pasca is a professor at Stanford University who is using 3D cultures to understand human brain development. Pasca and his lab have previously published methods to make different types of brain organoids from induced pluripotent stem cells (iPSCs) that recapitulate human brain developmental events in a dish.

Sergiu Pasca, Stanford University (Image credit: Steve Fisch)

My colleague, Todd Dubnicoff, blogged about Pasca’s research last year:

“Using brain tissue grown from patient-derived iPSCs, Dr. Sergiu Pasca and his team recreated the types of nerve cell circuits that form during the late stages of pregnancy in the fetal cerebral cortex, the outer layer of the brain that is responsible for functions including memory, language and emotion. With this system, they observed irregularities in the assembly of brain circuitry that provide new insights into the cellular and molecular causes of neuropsychiatric disorders like autism.”

Pasca generated brain organoids from the iPSCs of patients with a genetic disease called Timothy Syndrome – a condition that causes heart problems and some symptoms of autism spectrum disorder in children. By comparing the nerve cell circuits in patient versus healthy brain organoids, he observed a disruption in the migration of nerve cells in the organoids derived from Timothy Syndrome iPSCs.

“We’ve never been able to recapitulate these human-brain developmental events in a dish before,” said Pasca in a press release, “the process happens in the second half of pregnancy, so viewing it live is challenging. Our method lets us see the entire movie, not just snapshots.”

The Rise of 3D Brain Cultures

Pasca’s lab is just one of many that are working with 3D brain culture technologies to study human development and disease. These technologies are rising in popularity amongst scientists because they make it possible to study human brain tissue in normal and abnormal conditions. Brain organoids have also appeared in the mainstream news as novel tools to study how epidemics like the Zika virus outbreak affect the developing fetal brain (more here and here).

While these advances are exciting and promising, the field is still in its early stages and the 3D organoid models are far from perfect at representing the complex biology of the human brain.

Pasca addresses the progress and the hurdles of 3D brain cultures in a review article titled “The rise of three-dimensional brain cultures” published this week in the journal Nature. The article, describes in detail how pluripotent stem cells can assemble into structures that represent different regions of the human brain allowing scientists to observe how cells interact within neural circuits and how these circuits are disrupted by disease.

The review goes on to compare different approaches for creating 3D brain cultures (see figure below) and their different applications. For instance, scientists are culturing organoids on microchips (brains-on-a-chip) to model the blood-brain barrier – the membrane structure that protects the brain from circulating pathogens in the blood but also makes drug delivery to brain very challenging. Brain organoids are also being used to screen for new drugs and to model complex diseases like Alzheimer’s.

Human pluripotent stem cells, adult stem cells or cancer cells  can be used to derive microfluidics-based organs-on-a-chip (top), undirected organoids (middle), and region-specific brain organoids or organ spheroids (bottom). These 3D cultures can be manipulated with CRISPR-Cas9 genome-editing technologies, transplanted into animals or used for drug screening. (Pasca, Nature)

Pasca ends the review by identifying the major hurdles facing 3D brain culture technologies. He argues that “3D cultures only approximate the appearance and architecture of neural tissue” and that the cells and structures within these organoids are not always predictable. These issues can be address over time by enforcing quality control in how these 3D cultures are made and by using new biomaterials that enable the expansion and maturation of these cultures.

Nonetheless, Pasca believes that 3D brain cultures combined with advancing technologies to study them have “the potential to give rise to novel features for studying human brain development and disease.”

He concludes the review with a cautiously optimistic outlook:

“This is an exciting new field and as with many technologies, it may follow a ‘hype’ cycle in which we overestimate its effects in the short run and underestimate its effects in the long run. A better understanding of the complexity of this platform, and bringing interdisciplinary approaches will accelerate our progress up a ‘slope of enlightenment’ and into the ‘plateau of productivity’.”

3D brain culture from the Pasca Lab, Stanford University


Related Links:

Stem cell-derived, 3D brain tissue reveals autism insights

Studying human brain disorders is one of the most challenging fields in biomedical research. Besides the fact that the brain is incredibly complex, it’s just plain difficult to peer into it.

It’s neither practical nor ethical to access the cells of the adult brain. Patrick J. Lynch, medical illustrator; C. Carl Jaffe, MD, cardiologist.

For one thing, it’s not practical, let alone ethical, to drill into an affected person’s skull and collect brain cells to learn about their disease. Another issue is that the faulty cellular and molecular events that cause brain disorders are, in many cases, thought to trace back to fetal brain development before a person is even born. So, just like a detective looking for evidence at the scene of a crime, neurobiologists can only piece together clues after the disease has already occurred.

The good news is these limitations are falling away thanks to human induced pluripotent stem cells (iPSCs), which are generated from an individual’s easily accessible skin cells. Last week’s CIRM-funded research report out of Stanford University is a great example of how this method is providing new human brain insights.

Using brain tissue grown from patient-derived iPSCs, Dr. Sergiu Pasca and his team recreated the types of nerve cell circuits that form during the late stages of pregnancy in the fetal cerebral cortex, the outer layer of the brain that is responsible for functions including memory, language and emotion. With this system, they observed irregularities in the assembly of brain circuitry that provide new insights into the cellular and molecular causes of neuropsychiatric disorders like autism.

Recreating interactions between different regions of the development from skin-derived iPSCs
Image: Sergui Pasca Lab, Stanford University

Holy Brain Balls! Recreating the regions of our brain with skin cells
Two years ago, Pasca’s group figured out a way grow iPSCs into tiny, three-dimensional balls of cells that mimic the anatomy of the cerebral cortex. The team showed that these brain spheres contain the expected type of nerve cells, or neurons, as well as other cells that support neuron function.

Still, the complete formation of the cortex’s neuron circuits requires connections with another type of neuron that lies in a separate region of the brain. These other neurons travel large distances in a developing fetus’ brain over several months to reach the cortical cortex. Once in place, these migrating neurons have an inhibitory role and can block the cortical cortex nerve signals. Turning off a nerve signal is just as important as turning one on. In fact, imbalances in these opposing on and off nerve signals are suspected to play a role in epilepsy and autism.

So, in the current Nature study, Pasca’s team devised two different iPSC-derived brain sphere recipes: one that mimics the neurons found in the cortical cortex and another that mimics the region that contains the inhibitory neurons. Then the researchers placed the two types of spheres in the same lab dish and within three days, they spontaneously fused together.

Under video microscopy, the migration of the inhibitory neurons into the cortical cortex was observed. In cells derived from healthy donors, the migration pattern of inhibitory neurons looked like a herky-jerkey car being driven by a student driver: the neurons would move toward the cortical cortex sphere but suddenly stop for a while and then start their migration again.

“We’ve never been able to recapitulate these human-brain developmental events in a dish before,” said Pasca in a press release, “the process happens in the second half of pregnancy, so viewing it live is challenging. Our method lets us see the entire movie, not just snapshots.”

New insights into Timothy Syndrome may also uncover molecular basis of autism
To study the migration of the inhibitory neurons in the context of a neuropsychiatric disease, iPSCs were generated from skin samples of patients with Timothy syndrome, a rare genetic disease which carries a wide-range of symptoms including autism as well as heart defects.

The formation of brain spheres from the patient-derived iPSCs proceeded normally. But the next part of the experiment revealed an abnormal migration pattern of the neurons.  The microscopy movies showed that the start and stop behavior of neurons happened more frequently but the speed of the migration slowed. The fascinating video below shows the differences in the migration patterns of a healthy (top) versus a Timothy sydrome-derived neuron (bottom). The end result was a disruption of the typically well-organized neuron circuitry.

Now, the gene that’s mutated in Timothy Syndrome is responsible for the production of a protein that helps shuttle calcium in and out of neurons. The flow of calcium is critical for many cell functions and adding drugs that slow down this calcium flux restored the migration pattern of the neurons. So, the researchers can now zero in their studies on this direct link between the disease-causing mutation and a specific breakdown in neuron function.

The exciting possibility is that, because this system is generated from a patient’s skin cells, experiments could be run to precisely understand each individual’s neuropsychiatric disorder. Pasca is eager to see what new insights lie ahead:

“Our method of assembling and carefully characterizing neuronal circuits in a dish is opening up new windows through which we can view the normal development of the fetal human brain. More importantly, it will help us see how this goes awry in individual patients.”

CIRM-funded team uncovers novel function for protein linked to autism and schizophrenia

Imagine you’ve just stopped your car at the top of the steepest street in San Francisco. Now, if want to stay at the top of the hill you’re going to need to keep your foot on the brakes. Let go and you’ll start rolling down. Fast.

Don’t step off the brake pedal! Photo: Wikipedia

Conceptually, similar decision points happen in human development. A brain cell, for instance, has the DNA instructions to become any cell in the body but must “keep the brakes on”, or repress, genes responsible for other cell types. Release the silencing of those genes and the brain cell’s properties will get pulled toward other fates.

That’s the subject of a CIRM-funded research study published today in Nature which reports on the identification of a new type of repressor protein which opens up a new understanding of how brain cells establish and keep their identity. That may not sound so exciting to our non-scientist readers but this discovery could lead to new therapy approaches for neurological disorders like autism, schizophrenia, major depression and low I.Q.

Skin cells to brain cells with just three genes
In previous experiments, this Stanford University research team led by Marius Wernig, showed it’s possible to convert a skin cell to a brain cell, or neuron, by adding just three genes to the cells, including one called Myt1l. The other two genes were known to act as master “on switches” that activate a cascade of genes responsible for making neuron-specific proteins. Myt1l also helped increase the efficiency of this direct reprogramming but it’s exact role in the process wasn’t clear.

Direct conversion of skin cell into a neuron.
Image: Wernig Lab, Stanford

A closer examination of Myt1l protein function revealed that instead of being an on switch for neuron-specific genes, it was actually an off switch for skin-specific genes. Now, there’s nothing unusual about the existence of a protein that represses gene activity to help determine cell identity. But up until now, these repressors were thought to be “lineage specific” meaning they specifically switched off genes of a specific cell type. For example, a well-studied repressor called REST affects cell fate by putting the brakes on only nerve-specific genes. The case of Myt1l was different.

Many but one
The researchers found that, in brain cells, Myt1l not only blocked the activation of skin-specific genes, it also shut down genes related to lung, cartilage, heart and other cells fates. The one set of genes that Mytl1 repressor did not appear to act on was neuron-specific genes. From these results a “many but one” pattern emerged. That is; it seems Myt1l helps drive and maintain a neuron cell fate by shutting off gene networks for many different cell identities except for neurons. It’s a novel way to regulate cell fate, as Wernig explained in a press release:

Marius Wernig
Photo: Steve Fisch

“The concept of an inverse master regulator, one that represses many different developmental programs rather than activating a single program, is a unique way to control neuronal cell identity, and a completely new paradigm as to how cells maintain their cell fate throughout an organism’s lifetime.”

To build a stronger case for Myt1l function, the team looked at the effect of blocking the protein in the developing mouse brain. Sure enough, lifting Myt1l repression lead to a decrease in the number of neurons in the brain. Wernig described the impact of also inhibiting Myt1l in mature neurons:

“When this protein is missing, neural cells get a little confused. They become less efficient at transmitting nerve signals and begin to express genes associated with other cell fates.”

Potential cures can be uncovered withfundamental lab research
It turns out that Myt1l mutations have been recently found in people with autism, schizophrenia, major depression and low I.Q. Based on their new insights, the author suggest that in adults, these disorders may be caused by a neuron’s inability to maintain its identity rather than by a more permanent abnormality that occurred during fetal brain development. This hypothesis presents the exciting possibility of developing therapies that could improve symptoms.

One scientist’s quest to understand autism using stem cells

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.


Related Links:

Stories that caught our eye: stem cell transplants help put MS in remission; unlocking the cause of autism; and a day to discover what stem cells are all about

multiple-sclerosis

Motor neurons

Stem cell transplants help put MS in remission: A combination of high dose immunosuppressive therapy and transplant of a person’s own blood stem cells seems to be a powerful tool in helping people with relapsing-remitting multiple sclerosis (RRMS) go into sustained remission.

Multiple sclerosis (MS) is an autoimmune disorder where the body’s own immune system attacks the brain and spinal cord, causing a wide variety of symptoms including overwhelming fatigue, blurred vision and mobility problems. RRMS is the most common form of MS, affecting up to 85 percent of people, and is characterized by attacks followed by periods of remission.

The HALT-MS trial, which was sponsored by the National Institute of Allergy and Infectious Diseases (NIAID), took the patient’s own blood stem cells, gave the individual chemotherapy to deplete their immune system, then returned the blood stem cells to the patient. The stem cells created a new blood supply and seemed to help repair the immune system.

Five years after the treatment, most of the patients were still in remission, despite not taking any medications for MS. Some people even recovered some mobility or other capabilities that they had lost due to the disease.

In a news release, Dr. Anthony Fauci, Director of NIAID, said anything that holds the disease at bay and helps people avoid taking medications is important:

“These extended findings suggest that one-time treatment with HDIT/HCT may be substantially more effective than long-term treatment with the best available medications for people with a certain type of MS. These encouraging results support the development of a large, randomized trial to directly compare HDIT/HCT to standard of care for this often-debilitating disease.”

scripps-campus

Scripps Research Institute

Using stem cells to model brain development disorders. (Karen Ring) CIRM-funded scientists from the Scripps Research Institute are interested in understanding how the brain develops and what goes wrong to cause intellectual disabilities like Fragile X syndrome, a genetic disease that is a common cause of autism spectrum disorder.

Because studying developmental disorders in humans is very difficult, the Scripps team turned to stem cell models for answers. This week, in the journal Brain, they published a breakthrough in our understanding of the early stages of brain development. They took induced pluripotent stem cells (iPSCs), made from cells from Fragile X syndrome patients, and turned these cells into brain cells called neurons in a cell culture dish.

They noticed an obvious difference between Fragile X patient iPSCs and healthy iPSCs: the patient stem cells took longer to develop into neurons, a result that suggests a similar delay in fetal brain development. The neurons from Fragile X patients also had difficulty forming synaptic connections, which are bridges that allow for information to pass from one neuron to another.

Scripps Research professor Jeanne Loring said that their findings could help to identify new drug therapies to treat Fragile X syndrome. She explained in a press release;

“We’re the first to see that these changes happen very early in brain development. This may be the only way we’ll be able to identify possible drug treatments to minimize the effects of the disorder.”

Looking ahead, Loring and her team will apply their stem cell model to other developmental diseases. She said, “Now we have the tools to ask the questions to advance people’s health.”

A Day to Discover What Stem Cells Are All about.  (Karen Ring) Everyone is familiar with the word stem cells, but do they really know what these cells are and what they are capable of? Scientists are finding creative ways to educate the public and students about the power of stem cells and stem cell research. A great example is the University of Southern California (USC), which is hosting a Stem Cell Day of Discovery to educate middle and high school students and their families about stem cell research.

The event is this Saturday at the USC Health Sciences Campus and will feature science talks, lab tours, hands-on experiments, stem cell lab video games, and a resource fair. It’s a wonderful opportunity for families to engage in science and also to expose young students to science in a fun and engaging way.

Interest in Stem Cell Day has been so high that the event has already sold out. But don’t worry, there will be another stem cell day next year. And for those of you who don’t live in Southern California, mark your calendars for the 2017 Stem Cell Awareness Day on Wednesday, October 11th. There will be stem cell education events all over California and in other parts of the country during that week in honor of this important day.

 

 

CIRM Grantees Reflect on Ten Years of iPS Cells

For the fourth entry for our “Ten Years of Induced Pluripotent Stem (iPS) Cells” series, which we’ve been posting all month, I reached out to three of our CIRM grantees to get their perspectives on the impact of iPSC technology on their research and the regenerative medicine field as a whole:

granteesStep back in time for us to August 2006 when the landmark Takahashi/Yamanaka Cell paper was published which described the successful reprogramming of adult skin cells into an embryonic stem cell-like state, a.k.a. induced pluripotent stem (iPS) cells. What do you remember about your initial reactions to the study?

Sheng Ding, MD, PhD
Senior Investigator, Gladstone Institute of Cardiovascular Disease
Shinya had talked about the (incomplete) iPS cell work well before his 2006 publication in several occasions, so seeing the paper was not a total surprise.

Alysson Muotri, PhD
Associate Professor, UCSD Dept. of Pediatrics/Cellular & Molecular Medicine
At that time, I was a postdoc. I was in a meeting when Shinya first presented his findings. I think he did not give the identity of the 4 factors at that time. I was very excited but remember hearing rumors in the corridors saying the data was too good to be true. Soon after, the publication come out and it was a lot of fun reading it.

Joseph Wu, MD, PhD
Director, Stanford Cardiovascular Institute
I remember walking to the parking lot after work. One of my colleagues called me on my cell phone and he asked if I had seen “the Cell paper” published earlier that day. I said I haven’t and I would look it up when I get back home. I read it that night and found it quite interesting because the concept was simple but yet powerful.

How soon after the publication did you start using the iPSC technique in your own research? At that time, what research questions were you able to start exploring that weren’t possible in the “pre-iPS” era?

Ding:
I think many of us in the (pluripotent stem cell) field quickly jumped on this seminal discovery and started working on the iPSC technology itself as, at the time, there were many aspects of the discovery that would need to be better understood and further improved for its applications.

Muotri:
Immediately after the first mouse Cell paper, but I started with human cells. There were some concerns if the 4 factors will also work in humans. Nonetheless, I start using the mouse cDNA factors in human cells and it worked! I was amazed to witness the transformation and see the iPSC colonies in my dish – I showed the results to everyone in the lab.

Soon after, the papers showing that the procedure worked in human cells were published but I already knew that. Thus, I started to apply this to model disease, my main focus. In 2010, we published the modeling of the first neurodevelopmental disease using the iPSC technology. It is still a landmark publication, and I am very happy to be among the pioneers who believed in the Yamanaka technology.

Wu:
We started working on iPS cells about a couple of months after the initial publication. To our surprise, it was incredibly easy to reproduce, and we were able to get successful clones after a few initial attempts, in part because we had already been working on human embryonic stem (ES) cells for several years.

I think the biggest advantage of iPS cells is that we can know the medical record of the donor. So we can study the correlation between the donor’s underlying genetic makeup and their resulting cellular and whole-body characteristics using iPS cells as a platform for integrating these analyses. Examining these correlations is simply not possible with ES cells since no adult donor exists.

Dr. Ding, what do you think made you and your research team especially skilled at pioneering the use of small molecules to replace the “Yamanaka” reprogramming factors?

Ding:
We had been working on identifying and using small molecules to modulate stem cell fate (including cell proliferation, differentiation, and reprogramming) before iPS cell technology was reported. So when the iPS cell work was reported, it was obvious to us that we could apply our expertise in small molecule discovery to better understand and improve iPS cell reprogramming and replace the genetic factors by pharmacological approaches.

Now, come back to the present and reflect on how the paper has impacted your research over the past 10 years. Describe some of the key findings your lab has made over the past 10 years through iPSC studies

Ding:
We’ve worked on three aspects that are related to iPS cell research: one is to identify small molecule drugs that can functionally replace the genetic reprogramming factors, and enhance reprogramming efficiency and iPS cell quality (to mitigate risks associated with genetic manipulation, to make the iPS cell generation process more robust and efficient, and reduce the cost etc).

Second is to better understand the reprogramming mechanisms, that would allow us to improve reprogramming and better utilize cellular reprogramming technology. For example, we had uncovered and characterized several fundamental mechanisms underlying the reprogramming process.

The third is to “repurpose/re-direct” the iPS cell reprogramming into directly generating tissue/organ-specific precursor cells without generating iPS cell (itself, which is tumorigenic and needs to be differentiated for most of its applications). This so-called “Cell-Activation and Signaling-Directed/CASD” reprogramming approach allowed us to directly generate cells in the brain, heart, pancreas, liver, and blood vessels.

Muotri:
My lab has focused on the use of iPS cells to model autism spectrum disorder, a condition that is very heterogeneous both clinically and genetically. Previous models for autism, such as animals and postmortem tissues, were limited because we could not have access to live neurons to test experimentally several hypotheses. Thus, the attractiveness of the iPS cell model, by capturing the genome of patients in pluripotent stem cells and then guide them to become neural networks.

While the modeling in a dish was a great potential, there were some clear limitations too: the variability in the system was too high for example. My lab has worked hard to develop a chemically-defined culture media (iDEAL) to grow iPS cells and reduce the variability in the system. Moreover, we have developed robust protocols to analyze the morphology and electrophysiological properties of cortical neurons derived from iPS cells. We have used these methods to learn more about how genes impact neuronal networks and to screen drugs for several diseases.

We also used these methods to create cerebral organoids or “mini-brains” in a dish and have applied this technology to test the impact of several genetic and environmental factors. For example, we recently showed that the Zika virus could target neural progenitor cells in these organoids, leading to defects in the human developing cortex. Without this technology, we would be limited to mouse models that do not recapitulate the microcephaly of the babies born in Brazil.

Wu:
Our lab has taken advantage of the iPS cell platform to better understand cardiovascular diseases and to advance the precision medicine initiative. For example, we have used iPS cells to elucidate the molecular mechanisms of diseases related to an enlarged heart, cardiac arrhythmias, viral- and chemotherapy-induced heart disease, the genetics of coronary artery disease, among other diseases. We have also used iPS cells for testing the safety and efficacy of various cardiovascular drugs (i.e., “clinical trial in a dish”).

How are your findings important in terms of accelerating stem cell treatments to patients with unmet medical needs?

Ding:
Better understanding the reprogramming process and developing small molecule drugs for enhancing reprogramming would allow more effective generation of safe stem cells with reduced cost for treating diseases or doing research.

Muotri:
We work with two concepts. First, we screen drugs that could repair the disorder at a cellular level in a dish, hoping these drugs will be useful for a large fraction of autistic individuals. This approach can also be used to stratify the autistic population, finding subgroups that are more responsive to a particular drug. This strategy should help future clinical trials.

In parallel, we also work with the idea of personalized medicine by using patient-derived cells to create “disease in a dish” models in the lab. We then examine the genomic information of these cells to help us find drugs that are more specific to that individual. This approach should allow us to better design the treatment, testing ideal drugs and dosage, before prescribing it to the patient.

Wu:
The iPS cell technology provides us with an unprecedented glimpse into cardiovascular developmental biology. With this knowledge, we should be able to better understand how cardiac and vascular cells regenerate in the heart during different phases of human life and also during times of stress such as in the case of a heart attack. However, to be able to translate this knowledge into clinical care for patients will take a significant amount of time. This is because we still need to tackle the issues of immunogenicity, tumorigenicity, and safety for products that are derived from ES and iPS cells. Equally importantly, we need to understand how transplanted cells integrate into the patient because based on our experience so far, most of the injected cells die upon transplant into the heart. Finally, the economics of this type of personalized regenerative medicine is a daunting challenge.

Finally, it’s foolhardy to predict the future but, just for fun, imagine that I revisit you in August 2026. What key iPSC-related accomplishments do you think your lab will achieve by then?

Ding:
We are hoping to have cell-based therapy and small molecule drugs developed based on iPS cell-related research for treating human diseases. Particularly, we are also hoping our cellular reprogramming research would lead us to identify and develop small molecule drugs that control tissue/organ regeneration in vivo [in an animal].

Muotri:
We hope to have improved several steps on the neural differentiation, dramatically reducing costs and increasing efficiency.

Wu:
We would like to use the iPS cell platform to discover several new drugs (or repurpose existing drugs) for our cardiovascular patients; to replace the current industry standard of drug toxicity testing using the hERG assay (which I believe is outdated); to predict what medications patients should be taking (i.e., precision cardiovascular medicine); and to elucidate risk index of genetic variants (in combination with genome editing approach).