ViaCyte Advances Cell Replacement Therapy for High Risk Type 1 Diabetes

San Diego regenerative medicine company ViaCyte announced this week that the Food and Drug Administration (FDA) approved their Investigational New Drug (IND) Application for PEC-Direct, a cell-based therapy to treat patients at risk for severe complications caused by type 1 diabetes. In the US, IND approval is the final regulatory step required before a therapy can be tested in clinical trials.

PEC-Direct is a combination therapy consisting of cells encapsulated in a device that aims to replace the insulin-producing islet cells of the pancreas destroyed in patients with type 1 diabetes. The device contains human stem cell-derived pancreatic progenitor cells that develop into insulin-secreting cells when the device is placed under the patient’s skin. Ports on the surface of the device allow blood vessels from the host to directly contact the cells within, allowing for engraftment of the transplanted cells and for their maturation into islet cells.  These cells can sense and regulate blood glucose levels by secreting the hormones found in islets, including insulin.

ViaCyte’s PEC-Direct device allows a patient’s blood vessels to integrate and make contact with the transplanted cells.

Because PEC-Direct allows for “direct vascularization”, in effect connecting the device to the blood system, patients will need to take immunosuppressive drugs to prevent rejection of the donor cells. ViaCyte is therefore testing this therapy in patients who are at risk for serious complications associated with type 1 diabetes like severe hypoglycemia where a patient’s blood sugar is so low they need immediate medical assistance.

Severe hypoglycemia can occur because people with diabetes must inject insulin to control elevated blood sugar, but the injections can exceed the patients’ needs. The resulting low blood sugar can lead to dizziness, irregular heartbeat, and unconsciousness, even death. In some cases, sufferers are not aware of their hypoglycemia symptoms, putting them at increased risk of these life-threatening complications.

ViaCyte’s President and CEO, Dr. Paul Laikind, explained in a news release,

Paul Laikind

“While insulin therapy transformed type 1 diabetes from a death sentence to a chronic illness, it is far from a cure. Type 1 diabetes patients continue to deal with the daily impact of the disease and remain at risk for often severe long-term complications.  This is especially true for the patients with high-risk type 1 diabetes, who face challenges such as hypoglycemia unawareness and life-threatening severe hypoglycemic episodes.  These patients have a particularly urgent unmet medical need and could benefit greatly from cell replacement therapy.”

Approximately 140,000 people in the US and Canada suffer from this form of high-risk diabetes. These patients qualify for islet transplants from donated cadaver tissue. But because donor islets are in limited supply, ViaCyte Clinical Advisor, Dr. James Shapiro at the University of Alberta, believes PEC-Direct will address this issue by providing an unlimited supply of cells.

“Islet transplants from scarce organ donors have offered great promise for those with unstable, high-risk type 1 diabetes, but the procedure has many limitations.  With an unlimited supply of new islets that the stem cell-derived therapy promises, we have real potential to benefit far more patients with islet cell replacement.”

The company’s preclinical research on PEC-Direct, leading up to the FDA’s IND approval, was funded by a CIRM late stage preclinical grant. ViaCyte now plans to launch a clinical trial this year that will evaluate the safety and efficacy of PEC-Direct in the US and Canada. They will enroll approximately 40 patients at multiple clinical trial centers including the University of Alberta in Edmonton, the University of Minnesota, and UC San Diego. The trial will test whether the device is safe and whether the transplanted cells can produce enough insulin to relieve patients of insulin injections and hypoglycemic events.

ViaCyte has another product called PEC-Encap, a different implantable device that contains the same cells but protects these cells from the patient’s immune system. The device is being tested in a CIRM-funded Phase 1/2a trial, and ViaCyte is currently collaborating with W. L. Gore & Associates to improve the design of PEC-Encap to improve consistency of engraftment in patients.

Bridging the Gap: Regenerating Injured Bones with Stem Cells and Gene Therapy

Scientists from Cedars-Sinai Medical Center have developed a new stem cell-based technology in animals that mends broken bones that can’t regenerate on their own. Their research was published today in the journal Science Translational Medicine and was funded in part by a CIRM Early Translational Award.

Over two million bone grafts are conducted every year to treat bone fractures caused by accidents, trauma, cancer and disease. In cases where the fractures are small, bone can repair itself and heal the injury. In other cases, the fractures are too wide and grafts are required to replace the missing bone.

It sounds simple, but the bone grafting procedure is far from it and can cause serious problems including graft failure and infection. People that opt to use their own bone (usually from their pelvis) to repair a bone injury can experience intense pain, prolonged recovery time and are at risk for nerve injury and bone instability.

The Cedars-Sinai team is attempting to “bridge the gap” for people with severe bone injuries with an alternative technology that could replace the need for bone grafts. Their strategy combines “an engineering approach with a biological approach to advance regenerative engineering” explained co-senior author Dr. Dan Gazit in a news release.

Gazit’s team developed a biological scaffold composed of a protein called collagen, which is a major component of bone. They implanted these scaffolds into pigs with fractured leg bones by inserting the collagen into the gap created by the bone fracture. Over a two-week period, mesenchymal stem cells from the animal were recruited into the collagen scaffolds.

To ensure that these stem cells generated new bone, the team used a combination of ultrasound and gene therapy to stimulate the stem cells in the collagen scaffolds to repair the bone fractures. Ultrasound pulses, or high frequency sound waves undetectable by the human ear, temporarily created small holes in the cell membranes allowing the delivery of the gene therapy-containing microbubbles into the stem cells.

Image courtesy of Gazit Group/Cedars-Sinai.

Animals that received the collagen transplant and ultrasound gene therapy repaired their fractured leg bones within two months. The strength of the newly regenerated bone was comparable to successfully transplanted bone grafts.

Dr. Gadi Pelled, the other senior author on this study, explained the significance of their research findings for treating bone injuries in humans,

“This study is the first to demonstrate that ultrasound-mediated gene delivery to an animal’s own stem cells can effectively be used to treat non-healing bone fractures. It addresses a major orthopedic unmet need and offers new possibilities for clinical translation.”

You can learn more about this study by watching this research video provided by the Gazit Group at Cedars-Sinai.


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Kidney Disease: There’s an Organ-on-a-Chip for That

“There’s an app for that” is a well-known phrase trademarked by Apple to promote how users can do almost anything they do on a computer on their mobile phone. Apps are so deeply ingrained in everyday life that it’s hard for some people to imagine living without them. (I know I’d be lost without google maps or my Next Bus app!)

An estimated 2.2 million mobile apps exist for iPhones. Imagine if this multitude of apps were instead the number of stem cell models available for scientists to study human biology and disease. Scientists dream of the day when they can respond to questions about any disease and say, “there’s a model for that.” However, a future where every individual or disease has its own personalized stem cell line is still far away.

In the meantime, scientists are continuing to generate stem cell-based technologies that answer important questions about how our tissues and organs function and what happens when they are affected by disease. One strategy involves growing human stem cells on microchips and developing them into miniature organ systems that function like the organs in our bodies.

Kidney-on-a-chip

A group of scientists from Harvard’s Wyss Institute are using organ-on-a-chip technology to model a structure in the human kidney, called a glomerulus, that’s essential for filtering the body’s blood. It’s made up of a meshwork of blood vessels called capillaries that remove waste, toxic products, and excess fluid from the blood by depositing them into the urine.

The glomerulus also contains cells called podocytes that wrap around the capillaries and leave thin slits for blood to filter through. Diseases that affect podocytes or the glomerulus structure can cause kidney failure early or later in life, which is why the Harvard team was so interested to model this structure using their microchip technology.

They developed a method to mature human pluripotent stem cells into podocytes by engineering an environment similar to that of a real kidney on a microchip. Using a combination of kidney-specific factors and extracellular matrix molecules, which form a supportive environment for cells within tissues and organs, the team generated mature podocytes from human stem cells in three weeks. Their study was published in Nature Biomedical Engineering and was led by Dr. Donald Ingber, Founding Director of the Wyss Institute.

3D rendering of the glomerulus-on-a-chip derived from human stem cells. (Wyss Institute at Harvard University)

First author, Samaira Musah, explained how their glomerulus-on-a-chip works in a news release,

“Our method not only uses soluble factors that guide kidney development in the embryo, but, by growing and differentiating stem cells on extracellular matrix components that are also contained in the membrane separating the glomerular blood and urinary systems, we more closely mimic the natural environment in which podocytes are induced and mature. We even succeeded in inducing much of this differentiation process within a channel of the microfluidic chip, where by applying cyclical motions that mimic the rhythmic deformations living glomeruli experience due to pressure pulses generated by each heartbeat, we achieve even greater maturation efficiencies.”

Over 90% of stem cells successfully developed into functional podocytes that could properly filter blood by selectively filtering different blood proteins. The podocytes also were susceptible to a chemotherapy drug called doxorubicin, proving that they are suitable for modeling the effects of drug toxicity on kidneys.

Kidney podocyte derived from human stem cells. (Wyss Institute)

Ingber highlighted the potential applications of their glomerulus-on-a-chip technology,

Donald Ingber, Wyss Institute

“The development of a functional human kidney glomerulus chip opens up an entire new experimental path to investigate kidney biology, carry out highly personalized modeling of kidney diseases and drug toxicities, and the stem cell-derived kidney podocytes we developed could even offer a new injectable cell therapy approach for regenerative medicine in patients with life-threatening glomerulopathies in the future.”

There’s an organ-on-a-chip for that!

The Wyss Institute team has developed other organ-on-chips including lungs, intestine, skin and bone marrow. These miniature human systems are powerful tools that scientists hope will “revolutionize drug development, disease modeling and personalized medicine” by reducing the cost of research and the reliance on animal models according to the Wyss Institute technology website.

What started out as a microengineering experiment in Ingber’s lab a few years ago is now transforming into a technology “that is now poised to have a major impact on society” Ingber further explained. If organs-on-chips live up to these expectations, you might one day hear a scientist say, “Don’t worry, there’s an organ-on-a-chip for that!”


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Scientists make stem cell-derived nerve cells damaged in spinal cord injury

The human spinal cord is an information highway that relays movement-related instructions from the brain to the rest of the body and sensory information from the body back to the brain. What keeps this highway flowing is a long tube of nerve cells and support cells bundled together within the spine.

When the spinal cord is injured, the nerve cells are damaged and can die – cutting off the flow of information to and from the brain. As a result, patients experience partial or complete paralysis and loss of sensation depending on the extent of their injury.

Unlike lizards which can grow back lost tails, the spinal cord cannot robustly regenerate damaged nerve cells and recreate lost connections. Because of this, scientists are looking to stem cells for potential solutions that can rebuild injured spines.

Making spinal nerve cells from stem cells

Yesterday, scientists from the Gladstone Institutes reported that they used human pluripotent stem cells to create a type of nerve cell that’s damaged in spinal cord injury. Their findings offer a new potential stem cell-based strategy for restoring movement in patients with spinal cord injury. The study was led by Gladstone Senior Investigator Dr. Todd McDevitt, a CIRM Research Leadership awardee, and was published in the journal Proceedings of the National Academy of Sciences.

The type of nerve cell they generated is called a spinal interneuron. These are specialized nerve cells in the spinal cord that act as middlemen – transporting signals between sensory neurons that connect to the brain to the movement-related, or motor, neurons that connect to muscles. Different types of interneurons exist in the brain and spinal cord, but the Gladstone team specifically created V2a interneurons, which are important for controlling movement.

V2a interneurons extend long distances in the spinal cord. Injuries to the spine can damage these important cells, severing the connection between the brain and the body. In a Gladstone news release, Todd McDevitt explained why his lab is particularly interested in making these cells to treat spinal cord injury.

Todd McDevitt, Gladstone Institutes

“Interneurons can reroute after spinal cord injuries, which makes them a promising therapeutic target. Our goal is to rewire the impaired circuitry by replacing damaged interneurons to create new pathways for signal transmission around the site of the injury.”

 

Transplanting nerve cells into the spines of mice

After creating V2a interneurons from human stem cells using a cocktail of chemicals in the lab, the team tested whether these interneurons could be successfully transplanted into the spinal cords of normal mice. Not only did the interneurons survive, they also set up shop by making connections with other nerve cells in the spinal cord. The mice that received the transplanted cells didn’t show differences in their movement suggesting that the transplanted cells don’t cause abnormalities in motor function.

Co-author on the paper, Dylan McCreedy, described how the transplanted stem cell-derived cells behaved like developing V2a interneurons in the spine.

“We were very encouraged to see that the transplanted cells sprouted long distances in both directions—a key characteristic of V2a interneurons—and that they started to connect with the relevant host neurons.”

Todd McDevitt (right), Jessica Butts (center) and Dylan McCreedy (left) created a special type of neuron from human stem cells that could potentially repair spinal cord injuries. (Photo: Chris Goodfellow, Gladstone)

A new clinical strategy?

Looking forward, the Gladstone team plans to test whether these V2a interneurons can improve movement in mice with spinal cord injury. If results look promising in mice, this strategy of transplanting V2a interneurons could be translated into human clinic trials although much more time and research are needed to get there.

Trials testing stem cell-based treatments for spinal cord injury are already ongoing. Many of them involve transplanting progenitor cells that develop into the different types of cells in the spine, including nerve and support cells. These progenitor cells are also thought to secrete important growth factors that help regenerate damaged tissue in the spine.

CIRM is funding one such clinical trial sponsored by Asterias Biotherapeutics. The company is transplanting oligodendrocyte progenitor cells (which make nerve support cells called oligodendrocytes) into patients with severe spinal cord injuries in their neck. The trial has reported encouraging preliminary results in all six patients that received a dose of 10 million cells. You can read more about this trial here.

What the Gladstone study offers is a different stem cell-based strategy for treating spinal cord injury – one that produces a specific type of spinal nerve cell that can reestablish important connections in the spinal cord essential for movement.

For more on this study, watch the Gladstone’s video abstract “Discovery Offers New Hope to Repair Spinal Cord.


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Stem Cell Patient Advocates, Scientists and Doctors Unite Around a Common Cause

Some phrases just bring a smile to your face: “It’s a girl/boy”, “Congratulations, you got the job”, and “Another beer sir?” (or maybe that last one is just me). One other phrase that makes me smile is “packed house”. That’s why I was smiling so much at our Patient Advocate Event at UC San Diego last week. The room was jammed with around 150 patients and patient advocates who had come to hear about the progress being made in stem cell research.

Jonathan Thomas, Chair of the CIRM governing Board, kicked off the event with a quick run-through of our research, focusing on our clinical trials. As we have now funded 29 clinical trials, it really was a quick run-through, but JT did focus on a couple of remarkable stories of cures for patients suffering from Severe Combined Immunodeficiency (SCID) and Chronic Granulomatous Disease.

His message was simple. We have come a long way, but we still have a long way to go to fulfill our mission of accelerating stem cell treatments to patients with unmet medical needs. We have a target of 40 new clinical trials by 2020 and JT stressed our determination to do everything we can to reach that goal.

David Higgins, Parkinson’s Disease Advocate and CIRM Board Member (Credit Cory Kozlovich, UCSD)

Next up was David Higgins, who has a unique perspective. David is a renowned scientist, he’s also the Patient Advocate for Parkinson’s disease on the CIRM Board, and he has Parkinson’s disease. David gave a heartfelt presentation on the changing role of the patient and their growing impact on health and science.

In the old days, David said, the patient was merely the recipient of whatever treatment a doctor determined was appropriate. Today, that relationship is much more like a partnership, with physician and patient working together to determine the best approach.

He said CIRM tries to live up to that model by engaging the voice of the patient and patient advocate at every stage of the approval process, from shaping concepts to assessing the scientific merits of a project and deciding whether to fund it, and then doing everything we can to help it succeed.

He said California can serve as the model, but that patients need to make their voices heard at the national level too, particularly in light of the proposed huge budget cuts for the National Institutes of Health.

Dr. Jennifer Braswell. (Credit Cory Kozlovich, UCSD)

U.C. San Diego’s Dr. Jennifer Braswell gave some great advice on clinical trials, focusing on learning how to tell a good trial from a questionable one, and the questions patients need to ask before agreeing to be part of one.

She said it has to:

  • Be at a highly regarded medical center
  • Be based on strong pre-clinical evidence
  • Involved well-informed and compassionate physicians and nurses
  • Acknowledge that it carries some risk.

“You all know that if it sounds too good to be true, it probably is. If someone says a clinical trial carries no risk that’s a red flag, you know that’s not true. There is risk. Good researchers work hard to reduce the risk as much as possible, but you cannot eliminate it completely.”

She said even sites such as www.clinicaltrials.gov – a list of all the clinical trials registered with the National Institutes of Health – have to be approached cautiously and that you should talk to your own physican before signing up for anything.

Finally, UC San Diego’s Dr. Catriona Jamieson talked about her research into blood cancers, and how her work would not have been possible without the support of CIRM. She also highlighted the growing number of trials being carried out at through the CIRM Alpha Stem Cell Clinic Network, which helps scientists and researchers share knowledge and resources, enabling them to improve the quality of the care they provide patients.

The audience asked the panelists some great questions about the need for;

  • A national patient database to make it easier to recruit people for clinical trials
  • For researchers to create a way of letting people know if they didn’t get into a clinical trial so the patients wouldn’t get their hopes up
  • For greater public education about physicians or clinics offering unproven therapies

Adrienne Shapiro, an advocate for sickle cell disease patients, asks a question at Thursday’s stem cell meeting in La Jolla. (Bradley J. Fikes)

The meeting showed the tremendous public interest in stem cell research, and the desire to move it ahead even faster.

This was the first of a series of free public events we are holding around California this year. Next up, Los Angeles. More details of that shortly.

Stem cell stories that caught our eye: developing the nervous system, aging stem cells and identical twins not so identical

Here are the stem cell stories that caught our eye this week. Enjoy!

New theory for how the nervous system develops.

There’s a new theory on the block for how the nervous system is formed thanks to a study published yesterday by UCLA stem cell scientists in the journal Neuron.

The theory centers around axons, thin extensions projecting from nerve cells that transmit electrical signals to other cells in the body. In the developing nervous system, nerve cells extend axons into the brain and spinal cord and into our muscles (a process called innervation). Axons are guided to their final destinations by different chemicals that tell axons when to grow, when to not grow, and where to go.

Previously, scientists believed that one of these important chemical signals, a protein called netrin 1, exerted its influence over long distances in a gradient-like fashion from a structure in the developing nervous system called the floor plate. You can think of it like a like a cell phone tower where the signal is strongest the closer you are to the tower but you can still get some signal even when you’re miles away.

The UCLA team, led by senior author and UCLA professor Dr. Samantha Butler, questioned this theory because they knew that neural progenitor cells, which are the precursors to nerve cells, produce netrin1 in the developing spinal cord. They believed that the netrin1 secreted from these progenitor cells also played a role in guiding axon growth in a localized manner.

To test their hypothesis, they studied neural progenitor cells in the developing spines of mouse embryos. When they eliminated netrin1 from the neural progenitor cells, the axons went haywire and there was no rhyme or reason to their growth patterns.

Left: axons (green, pink, blue) form organized patterns in the normal developing mouse spinal cord. Right: removing netrin1 results in highly disorganized axon growth. (UCLA Broad Stem Cell Research Center/Neuron)

A UCLA press release explained what the scientists discovered next,

“They found that neural progenitors organize axon growth by producing a pathway of netrin1 that directs axons only in their local environment and not over long distances. This pathway of netrin1 acts as a sticky surface that encourages axon growth in the directions that form a normal, functioning nervous system.”

Like how ants leave chemical trails for other ants in their colony to follow, neural progenitor cells leave trails of netrin1 in the spinal cord to direct where axons go. The UCLA team believes they can leverage this newfound knowledge about netrin1 to make more effective treatments for patients with nerve damage or severed nerves.

In future studies, the team will tease apart the finer details of how netrin1 impacts axon growth and how it can be potentially translated into the clinic as a new therapeutic for patients. And from the sounds of it, they already have an idea in mind:

“One promising approach is to implant artificial nerve channels into a person with a nerve injury to give regenerating axons a conduit to grow through. Coating such nerve channels with netrin1 could further encourage axon regrowth.”

Age could be written in our stem cells.

The Harvard Gazette is running an interesting series on how Harvard scientists are tackling issues of aging with research. This week, their story focused on stem cells and how they’re partly to blame for aging in humans.

Stem cells are well known for their regenerative properties. Adult stem cells can rejuvenate tissues and organs as we age and in response to damage or injury. However, like most house hold appliances, adult stem cells lose their regenerative abilities or effectiveness over time.

Dr. David Scadden, co-director of the Harvard Stem Cell Institute, explained,

“We do think that stem cells are a key player in at least some of the manifestations of age. The hypothesis is that stem cell function deteriorates with age, driving events we know occur with aging, like our limited ability to fully repair or regenerate healthy tissue following injury.”

Harvard scientists have evidence suggesting that certain tissues, such as nerve cells in the brain, age sooner than others, and they trigger other tissues to start the aging process in a domino-like effect. Instead of treating each tissue individually, the scientists believe that targeting these early-onset tissues and the stem cells within them is a better anti-aging strategy.

David Sadden, co-director of the Harvard Stem Cell Institute.
(Jon Chase/Harvard Staff Photographer)

Dr. Scadden is particularly interested in studying adult stem cell populations in aging tissues and has found that “instead of armies of similarly plastic stem cells, it appears there is diversity within populations, with different stem cells having different capabilities.”

If you lose the stem cell that’s the best at regenerating, that tissue might age more rapidly.  Dr. Scadden compares it to a game of chess, “If we’re graced and happen to have a queen and couple of bishops, we’re doing OK. But if we are left with pawns, we may lose resilience as we age.”

The Harvard Gazette piece also touches on a changing mindset around the potential of stem cells. When stem cell research took off two decades ago, scientists believed stem cells would grow replacement organs. But those days are still far off. In the immediate future, the potential of stem cells seems to be in disease modeling and drug screening.

“Much of stem cell medicine is ultimately going to be ‘medicine,’” Scadden said. “Even here, we thought stem cells would provide mostly replacement parts.  I think that’s clearly changed very dramatically. Now we think of them as contributing to our ability to make disease models for drug discovery.”

I encourage you to read the full feature as I only mentioned a few of the highlights. It’s a nice overview of the current state of aging research and how stem cells play an important role in understanding the biology of aging and in developing treatments for diseases of aging.

Identical twins not so identical (Todd Dubnicoff)

Ever since Takahashi and Yamanaka showed that adult cells could be reprogrammed into an embryonic stem cell-like state, researchers have been wrestling with a key question: exactly how alike are these induced pluripotent stem cells (iPSCs) to embryonic stem cells (ESCs)?

It’s an important question to settle because iPSCs have several advantages over ESCs. Unlike ESCs, iPSCs don’t require the destruction of an embryo so they’re mostly free from ethical concerns. And because they can be derived from a patient’s cells, if iPSC-derived cell therapies were given back to the same patient, they should be less likely to cause immune rejection. Despite these advantages, the fact that iPSCs are artificially generated by the forced activation of specific genes create lingering concerns that for treatments in humans, delivering iPSC-derived therapies may not be as safe as their ESC counterparts.

Careful comparisons of DNA between iPSCs and ESCs have shown that they are indeed differences in chemical tags found on specific spots on the cell’s DNA. These tags, called epigenetic (“epi”, meaning “in addition”) modifications can affect the activity of genes independent of the underlying genetic sequence. These variations in epigenetic tags also show up when you compare two different preparations, or cell lines, of iPSCs. So, it’s been difficult for researchers to tease out the source of these differences. Are these differences due to the small variations in DNA sequence that are naturally seen from one cell line to the other? Or is there some non-genetic reason for the differences in the iPSCs’ epigenetic modifications?

Marian and Vivian Brown, were San Francisco’s most famous identical twins. Photo: Christopher Michel

A recent CIRM-funded study by a Salk Institute team took a clever approach to tackle this question. They compared epigenetic modifications between iPSCs derived from three sets of identical twins. They still found several epigenetic variations between each set of twins. And since the twins have identical DNA sequences, the researchers could conclude that not all differences seen between iPSC cell lines are due to genetics. Athanasia Panopoulos, a co-first author on the Cell Stem Cell article, summed up the results in a press release:

“In the past, researchers had found lots of sites with variations in methylation status [specific term for the epigenetic tag], but it was hard to figure out which of those sites had variation due to genetics. Here, we could focus more specifically on the sites we know have nothing to do with genetics. The twins enabled us to ask questions we couldn’t ask before. You’re able to see what happens when you reprogram cells with identical genomes but divergent epigenomes, and figure out what is happening because of genetics, and what is happening due to other mechanisms.”

With these new insights in hand, the researchers will have a better handle on interpreting differences between individual iPSC cell lines as well as their differences with ESC cell lines. This knowledge will be important for understanding how these variations may affect the development of future iPSC-based cell therapies.

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.


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Stem cells reveal developmental defects in Huntington’s disease

Three letters, C-A-G, can make the difference between being healthy and having a genetic brain disorder called Huntington’s disease (HD). HD is a progressive neurodegenerative disease that affects movement, cognition and personality. Currently more than 30,000 Americans have HD and there is no cure or treatment to stop the disease from progressing.

A genetic mutation in the huntingtin gene. caused by an expanded repeat of CAG nucleotides, the building blocks of DNA that make our genes, is responsible for causing HD. Normal people have less than 26 CAG repeats while those with 40 or more repeats will get HD. The reasons are still unknown why this trinucleotide expansion causes the disease, but scientists hypothesize that the extra CAG copies in the huntingtin gene produce a mutant version of the Huntingtin protein, one that doesn’t function the way the normal protein should.

The HD mutation causes neurodegeneration.

As with many diseases, things start to go wrong in the body long before symptoms of the disease reveal themselves. This is the case for HD, where symptoms typically manifest in patients between the ages of 30 and 50 but problems at the molecular and cellular level occur decades before. Because of this, scientists are generating new models of HD to unravel the mechanisms that cause this disease early on in development.

Induced pluripotent stem cells (iPSCs) derived from HD patients with expanded CAG repeats are an example of a cell-based model that scientists are using to understand how HD affects brain development. In a CIRM-funded study published today in the journal Nature Neuroscience, scientists from the HD iPSC Consortium used HD iPSCs to study how the HD mutation causes problems with neurodevelopment.

They analyzed neural cells made from HD patient iPSCs and looked at what genes displayed abnormal activity compared to healthy neural cells. Using a technique called RNA-seq analysis, they found that many of these “altered” genes in HD cells played important roles in the development and maturation of neurons, the nerve cells in the brain. They also observed differences in the structure of HD neurons compared to healthy neurons when grown in a lab. These findings suggest that HD patients likely have problems with neurodevelopment and adult neurogenesis, the process where the adult stem cells in your brain generate new neurons and other brain cells.

After pinpointing the gene networks that were altered in HD neurons, they identified a small molecule drug called isoxazole-9 (Isx-9) that specifically targets these networks and rescues some of the HD-related symptoms they observed in these neurons. They also tested Isx-9 in a mouse model of HD and found that the drug improved their cognition and other symptoms related to impaired neurogenesis.

The authors conclude from their findings that the HD mutation disrupts gene networks that affect neurodevelopment and neurogenesis. These networks can be targeted by Isx-9, which rescues HD symptoms and improves the mental capacity of HD mice, suggesting that future treatments for HD should focus on targeting these early stage events.

I reached out to the leading authors of this study to gain more insights into their work. Below is a short interview with Dr. Leslie Thompson from UC Irvine, Dr. Clive Svendsen from Cedars-Sinai, and Dr. Steven Finkbeiner from the Gladstone Institutes. The responses were mutually contributed.

Leslie Thompson

Steven Finkbeiner

Clive Svendsen

 

 

 

 

 

 Q: What is the mission of the HD iPSC Consortium?

To create a resource for the HD community of HD derived stem cell lines as well as tackling problems that would be difficult to do by any lab on its own.  Through the diverse expertise represented by the consortium members, we have been able to carry out deep and broad analyses of HD-associated phenotypes [observable characteristics derived from your genome].  The authorship of the paper  – the HD iPSC consortium (and of the previous consortium paper in 2012) – reflects this goal of enabling a consortium and giving recognition to the individuals who are part of it.

Q: What is the significance of the findings in your study and what novel insights does it bring to the HD field?

 Our data revealed a surprising neurodevelopmental effect of highly expanded repeats on the HD neural cells.  A third of the changes reflected changes in networks that regulate development and maturation of neurons and when compared to neurodevelopment pathways in mice, showed that maturation appeared to be impacted.  We think that the significance is that there may be very early changes in HD brain that may contribute to later vulnerability of the brain due to the HD mutation.  This is compounded by the inability to mount normal adult neurogenesis or formation of new neurons which could compensate for the effects of mutant HTT.  The genetic mutation is present from birth and with differentiated iPSCs, we are picking up signals earlier than we expected that may reflect alterations that create increased susceptibility or limited homeostatic reserves, so with the passage of time, symptoms do result.

What we find encouraging is that using a small molecule that targets the pathways that came out of the analysis, we protected against the impact of the HD mutation, even after differentiation of the cells or in an adult mouse that had had the mutation present throughout its development.

Q: There’s a lot of evidence suggesting defects in neurodevelopment and neurogenesis cause HD. How does your study add to this idea?

Agree completely that there are a number of cell, mouse and human studies that suggest that there are problems with neurodevelopment and neurogenesis in HD.  Our study adds to this by defining some of the specific networks that may be regulating these effects so that drugs can be developed around them.  Isx9, which was used to target these pathways specifically, shows that even with these early changes, one can potentially alleviate the effects. In many of the assays, the cells were already through the early neurodevelopmental stages and therefore would have the deficits present.  But they could still be rescued.

Q: Has Isx-9 been used previously in cell or animal models of HD or other neurodegenerative diseases? Could it help HD patients who already are symptomatic?

The compound has not been used that we know of in animal models to treat neurodegeneration, although was shown to affect neurogenesis and memory in mice. Isx9 was used in a study by Stuart Lipton in Parkinson’s iPSC-derived neurons in one study and it had a protective effect on apoptosis [cell death] in a study by Ryan SD et al., 2013, Cell.

We think this type of compound could help patients who are symptomatic.  Isx-9 itself is a fairly pleiotropic drug [having multiple effects] and more research would be needed [to test its safety and efficacy].

Q: Have you treated HD mice with Isx-9 during early development to see whether the molecule improves HD symptoms?

Not yet, but we would like to.

Q: What are your next steps following this study and do you have plans to translate this research into humans?

We are following up on the research in more mature HD neurons and to determine at what stages one can rescue the HD phenotypes in mice.  Also, we would need to do pharmacodynamics and other types of assays in preclinical models to assess efficacy and then could envision going into human trials with a better characterized drug.  Our goal is to ultimately translate this to human treatments in general and specifically by targeting these altered pathways.

Stem Cell Stories that Caught our Eye: stem cell insights into anorexia, Zika infection and bubble baby disease

Here are some stem cell stories that caught our eye this past week. Some are groundbreaking science, others are of personal interest to us, and still others are just fun.

Stem cell model identifies new culprit for anorexia.

Eating disorders like anorexia nervosa are often thought to be caused by psychological disturbances or societal pressure. However, research into the genes of anorexia patients suggests that what’s written in your DNA can be associated with an increased vulnerability to having this disorder. But identifying individual genes at fault for a disease this complex has remained mostly out of scientists’ reach, until now.

A CIRM-funded team from the UC San Diego (UCSD) School of Medicine reported this week that they’ve developed a stem cell-based model of anorexia and used it to identify a gene called TACR1, which they believe is associated with an increased likelihood of getting anorexia.

They took skin samples from female patients with anorexia and reprogrammed them into induced pluripotent stem cells (iPSCs). These stem cells contained the genetic information potentially responsible for causing their anorexia. The team matured these iPSCs into brain cells, called neurons, in a dish, and then studied what genes got activated. When they looked at the genes activated by anorexia neurons, they found that TACR1, a gene associated with psychiatric disorders, was switched on higher in anorexia neurons than in healthy neurons. These findings suggest that the TACR1 gene could be an identifier for this disease and a potential target for developing new treatments.

In a UCSD press release, Professor and author on the study, Alysson Muotri, said that they will follow up on their findings by studying stem cell lines derived from a larger group of patients.

Alysson Muotri UC San Diego

“But more to the point, this work helps make that possible. It’s a novel technological advance in the field of eating disorders, which impacts millions of people. These findings transform our ability to study how genetic variations alter brain molecular pathways and cellular networks to change risk of anorexia nervosa — and perhaps our ability to create new therapies.”

Anorexia is a disease that affects 1% of the global population and although therapy can be an effective treatment for some, many do not make a full recovery. Stem cell-based models could prove to be a new method for unlocking new clues into what causes anorexia and what can cure it.

Nature versus Zika, who will win?

Zika virus is no longer dominating the news headlines these days compared to 2015 when large outbreaks of the virus in the Southern hemisphere came to a head. However, the threat of Zika-induced birth defects, like microcephaly to pregnant women and their unborn children is no less real or serious two years later. There are still no effective vaccines or antiviral drugs that prevent Zika infection but scientists are working fast to meet this unmet need.

Speaking of which, scientists at UCLA think they might have a new weapon in the war against Zika. Back in 2013, they reported that a natural compound in the body called 25HC was effective at attacking viruses and prevented human cells from being infected by viruses like HIV, Ebola and Hepatitis C.

When the Zika outbreak hit, they thought that this compound could potentially be effective at preventing Zika infection as well. In their new study published in the journal Immunity, they tested a synthetic version of 25HC in animal and primate models, they found that it protected against infection. They also tested the compound on human brain organoids, or mini brains in a dish made from pluripotent stem cells. Brain organoids are typically susceptible to Zika infection, which causes substantial cell damage, but this was prevented by treatment with 25HC.

Left to right: (1) Zika virus (green) infects and destroys the formation of neurons (pink) in human stem cell-derived brain organoids.  (2) 25HC blocks Zika infection and preserves neuron formation in the organoids. (3) Reduced brain size and structure in a Zika-infected mouse brain. (4) 25HC preserves mouse brain size and structure. Image courtesy of UCLA Stem Cell.

A UCLA news release summarized the impact that this research could have on the prevention of Zika infection,

“The new research highlights the potential use of 25HC to combat Zika virus infection and prevent its devastating outcomes, such as microcephaly. The research team will further study whether 25HC can be modified to be even more effective against Zika and other mosquito-borne viruses.”

Harnessing a naturally made weapon already found in the human body to fight Zika could be an alternative strategy to preventing Zika infection.

Gene therapy in stem cells gives hope to bubble-babies.

Last week, an inspiring and touching story was reported by Erin Allday in the San Francisco Chronicle. She featured Ja’Ceon Golden, a young baby not even 6 months old, who was born into a life of isolation because he lacked a properly functioning immune system. Ja’Ceon had a rare disease called severe combined immunodeficiency (SCID), also known as bubble-baby disease.

 

Ja’Ceon Golden is treated by patient care assistant Grace Deng (center) and pediatric oncology nurse Kat Wienskowski. Photo: Santiago Mejia, The Chronicle.

Babies with SCID lack the body’s immune defenses against infectious diseases and are forced to live in a sterile environment. Without early treatment, SCID babies often die within one year due to recurring infections. Bone marrow transplantation is the most common treatment for SCID, but it’s only effective if the patient has a donor that is a perfect genetic match, which is only possible for about one out of five babies with this disease.

Advances in gene therapy are giving SCID babies like Ja’Ceon hope for safer, more effective cures. The SF Chronicle piece highlights two CIRM-funded clinical trials for SCID run by UCLA in collaboration with UCSF and St. Jude Children’s Research Hospital. In these trials, scientists isolate the bone marrow stem cells from SCID babies, correct the genetic mutation causing SCID in their stem cells, and then transplant them back into the patient to give them a healthy new immune system.

The initial results from these clinical trials are promising and support other findings that gene therapy could be an effective treatment for certain genetic diseases. CIRM’s Senior Science Officer, Sohel Talib, was quoted in the Chronicle piece saying,

“Gene therapy has been shown to work, the efficacy has been shown. And it’s safe. The confidence has come. Now we have to follow it up.”

Ja’Ceon was the first baby treated at the UCSF Benioff Children’s Hospital and so far, he is responding well to the treatment. His great aunt Dannie Hawkins said that it was initially hard for her to enroll Ja’Ceon in this trial because she was a partial genetic match and had the option of donating her own bone-marrow to help save his life. In the end, she decided that his involvement in the trial would “open the door for other kids” to receive this treatment if it worked.

Ja’Ceon Golden plays with patient care assistant Grace Deng in a sterile play area at UCSF Benioff Children’s Hospital.Photo: Santiago Mejia, The Chronicle

It’s brave patients and family members like Ja’Ceon and Dannie that make it possible for research to advance from clinical trials into effective treatments for future patients. We at CIRM are eternally grateful for their strength and the sacrifices they make to participate in these trials.

Mixed Matches: How Your Heritage Can Save a Life

Today we bring you a guest blog from Athena Mari Asklipiadis. She’s the founder of Mixed Marrow, which is an organization dedicated to finding bone marrow and blood cell donors to patients of multiethnic descent. Athena helped produce a 2016 documentary film called Mixed Match that encourages mixed race and minority donors to register as adult donors.

Athena Asklipiadis

Due to the lack of diversity on the national and world bone marrow donor registries, Mixed Marrow was started in 2009 to increase the numbers of mixed race donors.

Prior to Mixed Marrow starting, other ethnic recruiters like Asians for Miracle Marrow Matches (A3M), based in Los Angeles, CA and Asian American Donor Program (AADP), based in Alameda, CA had been raising awareness in the Asian and minority communities for decades.  Closing the racial gap on the registry was something I was very much interested in helping them with so I began my outreach on the most familiar medium I knew—social media.

Because matching relies heavily on similar inherited genetic markers, I was particularly astonished seeing the less than 3% (back in 2009) sliver of the ethnic pie that mixed race donors made up.  Caucasians made up for about 70% at the time, with all minorities making up for the difference.  The ethnic breakdown made sense when comparing against actual population numbers, but a larger pool of minority donors was definitely something needed especially when multiracial people were being reported as the fastest growing demographic in the US.  Odds were just not in the favor of non-white searching patients.

Current Be The Match ethnic breakdown as of 2016.

After getting to know a local mixed race searching patient, Krissy Kobata, and hearing of her struggles finding a match, I knew I had to do my best to reach out to fellow multiracial people, most of which were young and likely online.  At the time, I was engaged with fellow hapas (half in Hawaiian Pidgin, referring mixed heritage) and mixed people via multiracial community Facebook groups and other internet forums.  One common thing I noticed, unlike topics like identity, food and culture– health was definitely not widely talked about. So with that lack of awareness, Mixed Marrow began as a facebook page and later as a website.  With the help of organizations like A3M supplying Be The Match testing kits, Mixed Marrow was able to also exist outside of the virtual world by hosting donor recruitment drives at different cultural and college events.

Athena Asklipiadis, Krissy Kobata and Mixed Match director, Jeff Chiba Stearns

After about a year of advocacy, in 2010, I connected with filmmaker Jeff Chiba Stearns to pitch an idea for a documentary on the patients I worked with.  Telling their stories in words and on flyers was not effective enough for me, I felt that more people would be inclined to register as a donor if they got to know the patients as well as I did.  Thus, the film Mixed Match was born.

Still from Mixed Match, Imani (center) and parents, Darrick and Tammy.

Still from Mixed Match, Imani mother, Tammy.

Over the course of the next 6 years, Jeff and I went on a journey across the US to gather not only patient stories, but input from pioneers in stem cell transplantation like Dr. Paul Terasaki and Dr. John E. Wagner.  It was so important to share these transplant tales while being as accurate and informed as possible.

Still from Mixed Match – Dr. Paul Teriyaki.

Our goal was to educate audiences and present a call-to-action where everyone can learn how they can save a life. Mixed Match not only highlights bone marrow and peripheral blood stem cell (PBSC) donation, but it also shares the possibilities of umbilical cord stem cells.

Mixed Match director, Jeff Chiba Stearns decided a great way to explain stem cell science and matching was through animation.  Stearns, with the help of animator, Kaho Yoshida, was able to reach across to non-medical expert audiences and create digestible and engaging imagery to teach what is usually very complex science.

Animation Still from Mixed Match.

At every screening we also make sure to host a bone marrow registry drive so audiences have the opportunity to sign up.  We have partnered with both the US national registry, Be The Match and Canadian Blood Services’ One Match registry.

Bone marrow drive at a Mixed Match screening in Toronto.

Nearly 8 years and about 40 cities later, Mixed Marrow has managed to spread advocacy for the need for more mixed race donors all over the US and even other countries like Canada, Japan, Korea and Austria all the while being completely volunteer-run.  It is our hope that through social media and film, Mixed Match, we can help share these important stories and save lives.

Further Information