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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Telomere length matters: scientists find shorter telomeres may cause aging-related disease

Aging is inevitable no matter how much you exercise, sleep or eat healthy. There is no magic pill or supplement that can thwart growing older. However, preventing certain age-related diseases is a different story. Genetic mutations can raise the risk of acquiring age-related diseases like heart disease, diabetes, cancer and dementia. And scientists are on the hunt for treatments that target these mutations in hopes of preventing these diseases from happening.

Telomeres shown in white act as protective caps at the ends of chromosomes.

Another genetic component that can accelerate diseases of aging are telomeres. These are caps made up of repeat sequences of DNA that sit at the ends of chromosomes and prevent the loss of important genetic material housed within chromosomes. Healthy cells have long telomeres, and ascells divide these telomeres begin to shorten. If telomere shortening is left unchecked, cells become unhealthy and either stop growing or self-destruct.

Cells have machinery to regrow their telomeres, but in most cases, the machinery isn’t activated and over time, the resulting shortened telomeres can lead to problems like an impaired immune system and organ degeneration. Shortened telomeres are associated with age-related diseases, but the reasons why have remained elusive until recently.

Scientists from the Gladstone Institutes have found a clue to this telomere puzzle that they shared in a study published yesterday in the Journal of Clinical Investigation. This research was funded in part by a CIRM Discovery stage award.

In their study, the team found that mice with a mutation that causes a heart condition known as calcific aortic valve disease (CAVD) were more likely to get the disease if they had short telomeres. CAVD causes the heart valves and vessels to turn hard as rock due to a buildup of calcium. It’s the third leading cause of heart disease and the only effective treatment requires surgery to replace the calcified parts of the heart.

Old age and mutations in one of the copies of the NOTCH1 gene can cause CAVD in humans. However, attempts to model CAVD in mice using the same NOTCH1 mutation have failed to produce symptoms of the disease. The team at Gladstone knew that mice inherently have longer telomeres than humans and hypothesized that these longer telomeres could protect mice with the NOTCH1 mutation from getting CAVD.

They decided to study NOTCH1 mutant mice that had short telomeres and found that these mice had symptoms of CAVD including hardened arteries. Furthermore, mice that had the shortest telomeres had the most severe heart-related symptoms.

First author on the study Christina Theodoris, explained in a Gladstone news release how telomere length matters in animal models of age-related diseases:

“Our findings reveal a critical role for telomere length in a mouse model of age-dependent human disease. This model provides a unique opportunity to dissect the mechanisms by which telomeres affect age-dependent disease and also a system to test novel therapeutics for aortic valve disease.”

Deepak Srivastava and Christina Theodoris created mouse models of CAVD that may be used to test drug therapies for the disease. (Photo: Chris Goodfellow, Gladstone Institutes)

The team believes that there is a direct relationship between short telomeres and CAVD, likely through alterations in the activity of gene networks related to CAVD. They also propose that telomere length could influence how severe the symptoms of this disease manifest in humans.

This study is important to the field because it offers a new strategy to study age-related diseases in animal models. Senior author on the study, Dr. Deepak Srivastava, elaborated on this concept:

Deepak Srivastava, Gladstone Institutes

“Historically, we have had trouble modeling human diseases caused by mutation of just one copy of a gene in mice, which impedes research on complex conditions and limits our discovery of therapeutics. Progressive shortening of longer telomeres that are protective in mice not only reproduced the clinical disease caused by NOTCH1 mutation, it also recapitulated the spectrum of disease severity we see in humans.”

Going forward, the Gladstone team will use their new mouse model of CAVD to test drug candidates that have the potential to treat CAVD in humans. If you want to learn more about this study, watch this Gladstone video featuring an interview of Dr. Srivastava about this publication.

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.

Stories that caught our eye: frail bones in diabetics, ethics of future IVF, Alzheimer’s

The connection between diabetes and frail bones uncovered
Fundamentally, diabetes is defined by abnormally high blood sugar levels. But that one defect over time carries an increased risk for a wide range of severe health problems. For instance, compared to healthy individuals, type 2 diabetics are more prone to poorly healing bone fractures – a condition that can dramatically lower one’s quality of life.

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Bones of the healthy animals (top) form larger calluses during healing which lead to stronger repaired bones. Bones of the diabetic mice (bottom) have smaller calluses and the healed bones are more brittle. Image: Stanford University

To help these people, researchers are trying to tease out how diabetes impacts bone health. But it’s been a complicated challenge since there are many factors at play. Is it from potential side effects of diabetes drugs? Or is the increased body weight associated with type 2 diabetes leading to decreased bone density? This week a CIRM-funded team at Stanford pinpointed skeletal stem cells, a type of adult stem cell that goes on to make all the building blocks of the bone, as important pieces to this scientific puzzle.

Reporting in Science Translational Medicine, the team, led by Michael Longaker – co-director of Stanford’s Institute for Stem Cell Biology and Regenerative Medicine – found that, compared to healthy animals, type 2 diabetic mice have a reduced number of skeletal stem cells after bone fracture. A study of the local cellular “neighborhood” of these stem cells showed that the diabetic mice also had a reduction in the levels of a protein called hedgehog. Blocking hedgehog activity in healthy mice led to the slow bone healing seen in the diabetic mice. More importantly, boosting hedgehog levels near the site of the fracture in diabetic mice lead to bone healing that was just as good as in the healthy mice.

To see if this result might hold up in humans, the team analyzed hedgehog levels in bone samples retrieved from diabetics and non-diabetics undergoing joint replacement surgeries. Sure enough, hedgehog was depleted in the diabetic bone exactly reflecting the mouse results.

Though more studies will be needed to develop a hedgehog-based treatment in humans, Longaker talked about the exciting big picture implications of this result in a press release:

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Michael Longaker

“We’ve uncovered the reason why some patients with diabetes don’t heal well from fractures, and we’ve come up with a solution that can be locally applied during surgery to repair the break. Diabetes is rampant worldwide, and any improvement in the ability of affected people to heal from fractures could have an enormously positive effect on their quality of life.”

 

Getting the ethics ahead of the next generation of fertility treatments
The Business Insider ran an article this week with a provocative title, “Now is the time to talk about creating humans from stem cells.” I initially read too much into that title because I thought the article was advocating the need to start the push for the cloning of people. Instead, author Rafi Letzter was driving at the importance for concrete, ethical discussion right now about stem cell technologies for fertility treatments that may not be too far off.

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These mice were born from artificial eggs that were made from stem cells in a dish.
It’s great news for infertility specialist but carries many ethical dilemmas. 
(Image: K. Hayashi, Kyushu University)

In particular, he alludes to a paper from October (read our blog about it) that reported the creation of female mouse eggs from stem cells. These eggs were fertilized, implanted into the mother and successfully developed into living mice. What’s more, one set of stem cells were derived from mouse skin samples via the induced pluripotent stem cell method. This breakthrough could one day make it possible for an infertile woman to simply go through a small skin biopsy or mouth swab to generate an unlimited number of eggs for in vitro fertilization (IVF). Just imagine how much more efficient, less invasive and less costly this procedure could be compared to current IVF methods that require multiple hormone injections and retrieval of eggs from a woman’s ovaries.

But along with that hope for couples who have trouble conceiving a child comes a whole host of ethical issues. Here, Letzter refers to a perspective letter published on Wednesday in Science Translation Medicine by scientists and ethicists about this looming challenge for researchers and policymakers.

It’s an important read that lays out the current science, the clinical possibilities and regulatory and ethical questions that must be addressed sooner than later. In an interview with Letzter, co-author Eli Adashi, from the Alpert Medical School at Brown University, warned against waiting too long to heed this call to action:

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Eli Adashi

“Let’s start the [ethical] conversation now. Like all conversations it will be time consuming. And depending how well we do it, and we’ve got to do it well, it will be demanding. It will not be wise to have that conversation when you’re seeing a paper in Science or Nature reporting the complete process in a human. That would not be wise on our collective part. We should be as much as possible ready for that.”

 

 

Tackling Frontotemporal dementia and Alzheimer’s by hitting the same target.
To develop new disease therapies, you usually need to understand what is going wrong at a cellular level. In some cases, that approach leads to the identification of a specific protein that is either missing or in short supply. But this initial step is just half the battle because it may not be practical to make a drug out of the protein itself. So researchers instead search for other proteins or small molecules that lead to an increase in the level of the protein.

A CIRM-funded project at the Gladstone Institutes has done just that for the protein called progranulin. People lacking one copy of the progranulin gene carry an increased risk for  frontotemporal dementia (FTD), a degenerative disease of the brain that is the most common cause of dementia in people under 60 years of age. FTD symptoms are often mistaken for Alzheimer’s. In fact, mutations in progranulin are also associated with Alzheimer’s.

Previous studies have shown that increasing levels of progranulin in animals with diseases that mimic FTP and Alzheimer’s symptoms can reverse symptoms. But little was known how progranulin protein levels were regulated in the cells. Amanda Mason, the lead author on the Journal of Biological Chemistry report, explained in a press release how they tackled this challenge:

“We wanted to know what might regulate the levels of progranulin. Many processes in biology are controlled by adding or removing a small chemical group called phosphate, so we started there.”

These phosphate groups hold a lot of energy in their chemical bonds and can be harnessed to activate or turn off the function of proteins and DNA. The team systematically observed the effects of enzymes that add and remove phosphate groups and zeroed in on one called Ripk1 that leads to increases in progranulin levels. Now the team has set their sights on Ripk1 as another potential target for developing a therapeutic that could be effective against both FTP and Alzheimer’s. Steve Finkbeiner, the team lead, gave a big picture perspective on these promising results:

finkbeiner-profile

Steve Finkbeiner

“This is an exciting finding. Alzheimer’s disease was discovered over 100 years ago, and we have essentially no drugs to treat it. To find a possible new way to treat one disease is wonderful. To find a way that might treat two diseases is amazing.”

 

Using stem cells to fix bad behavior in the brain

 

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Gladstone Institutes Steven Finkbeiner and Gaia Skibinski: Photo courtesy Chris Goodfellow, Gladstone Institutes

Diseases of the brain have many different names, from Alzheimer’s and Parkinson’s to ALS and Huntington’s, but they often have similar causes. Researchers at the Gladstone Institutes in San Francisco are using that knowledge to try and find an approach that might be effective against all of these diseases. In a new CIRM-funded study, they have identified one protein that could help do just that.

Many neurodegenerative diseases are caused by faulty proteins, which start to pile up and cause damage to neurons, the brain cells that are responsible for processing and transmitting information. Ultimately, the misbehaving proteins cause those cells to die.

The researchers at the Gladstone found a way to counter this destructive process by using a protein called Nrf2. They used neurons from humans (made from induced pluripotent stem cells – iPSCs – hence the stem cell connection here) and rats. They then tested these cells in neurons that were engineered to have two different kinds of mutations found in  Parkinson’s disease (PD) plus the Nrf2 protein.

Using a unique microscope they designed especially for this study, they were able to track those transplanted neurons and monitor what happened to them over the course of a week.

The neurons that expressed Nrf2 were able to render one of those PD-causing proteins harmless, and remove the other two mutant proteins from the brain cells.

In a news release to accompany the study in The Proceedings of the National Academy of Sciences, first author Gaia Skibinski, said Nrf2 acts like a house-cleaner brought in to tidy up a mess:

“Nrf2 coordinates a whole program of gene expression, but we didn’t know how important it was for regulating protein levels until now. Over-expressing Nrf2 in cellular models of Parkinson’s disease resulted in a huge effect. In fact, it protects cells against the disease better than anything else we’ve found.”

Steven Finkbeiner, the senior author on the study and a Gladstone professor, said this model doesn’t just hold out hope for treating Parkinson’s disease but for treating a number of other neurodegenerative problems:

“I am very enthusiastic about this strategy for treating neurodegenerative diseases. We’ve tested Nrf2 in models of Huntington’s disease, Parkinson’s disease, and ALS, and it is the most protective thing we’ve ever found. Based on the magnitude and the breadth of the effect, we really want to understand Nrf2 and its role in protein regulation better.”

The next step is to use this deeper understanding to identify other proteins that interact with Nrf2, and potentially find ways to harness that knowledge for new therapies for neurodegenerative disorders.

Understanding two heart problems by studying the domino effect of one gene network

Although heart muscle cells, or cardiomyocytes, are specialized to help pump blood to the organs, they nonetheless carry all the genetic instructions for becoming a nerve cell, an intestinal cell, a liver or any cell type in the body. But at the moment in time that the fetal heart begins to develop, master switch proteins, called transcription factors, act like the first tile in an extremely complex pattern of dominos and set off a chain of events which lead to the activation of heart muscle specific genes in cardiomyocytes as well as the silencing of genes important for the development other cells types.

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cardiomyocytes

It’s truly amazing that this process comes together to create functioning hearts in the about 355,000 babies that are born in the world each day. But it isn’t always flawless as heart defects occur in about 1% of all live births. By studying a family with a history of heart defects, scientists at the Gladstone Institutes have gained a deeper understanding of how gene networks go awry,  causing heart defects as well as heart disease later in life. This CIRM-funded work was published today in Cell.

Half the children in the family studied by the Gladstone team were born with a hole in the wall between the two chambers of the heart. Back in 2003, the family approached Deepak Srivastava, head of the cardiovascular institute at Gladstone, for help. A genetic analysis by Srivastava’s team found that all of the affected children carried a mutation in the GATA4 gene, which encodes a heart specific transcription factor protein. Seven years later the children developed heart disease that led to weaker heart pumping. Although the two heart problems were not related, they suspected both were caused by the GATA4 mutation and sought to understand how that could be the case.

Srivastava’s team sought to understand how the GATA4 mutation could be causing both health problems. They collected skin samples from the affected children and generated cardiomyocytes using the induced pluripotent stem cell technique. Cells were also collected from the children’s healthy siblings. In the laboratory, the cells were analyzed for how well they functioned, such as their ability to contract. All of these tests showed that the cells carrying the GATA4 mutation had impaired function compared to the healthy cells. These findings provide a basis for the heart disease found in the children during their teens.

In terms of the heart wall defect, the team examined the GATA4 protein’s interaction with the protein TBX5, another transcription factor that is also mutated in cases of this defect. Both proteins regulate genes by directly binding to DNA as well as interacting with each other. In cells with the defective GATA4, the research discovered TBX5 did not bind well to the DNA. The lack of TBX5 led to a disruption in the activation of genes that play a role in the development of the heart wall.

TBX5 and GATA4 also work together in cardiomyocytes to silence genes that play a role in other cell types. But the scientists found that the because the GATA4 mutation hindered its interaction with TBX5, those non-heart specific genes we’re no longer repressed causing further disruption to proper cardiomyocyte development. Srivastava summed up these results in an institute press release:

srivastava-profile

Deepak Srivastava

“By studying the patients’ heart cells in a dish, we were able to figure out why their hearts were not pumping properly. Investigating their genetic mutation revealed a whole network of genes that went awry, first causing septal [heart wall] defects and then the heart muscle dysfunction.”

Now, because GATA4 and TBX5 are those first domino tiles in very intricate networks of genes, targeting those proteins for future therapy development wouldn’t be wise. Their effects are so widespread that blocking their actions would do more harm than good. But finding drugs that might affect only a branch of GATA4/TBX5 actions could result in new therapy approaches to heart defects and disease.

deepak-yen-sin-22 Deepak Srivastava and Yen-Sin Ang [Photo: Chris Goodfellow, Gladstone Institutes]

Yen-Sin Ang, the first author on the report, thinks these finding could prove fruitful for other diseases as well:

“It’s amazing that by studying genes in a two-dimensional cluster of heart cells, we were able to discover insights into a disease that affects a complicated three-dimensional organ. We think this conceptual framework could be used to study other diseases caused by mutations in proteins that serve as master regulators of whole gene networks.”

Translating great stem cell ideas into effective therapies

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CIRM funds research trying to solve the Alzheimer’s puzzle

In science, there are a lot of terms that could easily mystify people without a research background; “translational” is not one of them. Translational research simply means to take findings from basic research and advance them into something that is ready to be tested in people in a clinical trial.

Yesterday our Governing Board approved $15 million in funding for four projects as part of our Translational Awards program, giving them the funding and support that we hope will ultimately result in them being tested in people.

Those projects use a variety of different approaches in tackling some very different diseases. For example, researchers at the Gladstone Institutes in San Francisco received $5.9 million to develop a new way to help the more than five million Americans battling Alzheimer’s disease. They want to generate brain cells to replace those damaged by Alzheimer’s, using induced pluripotent stem cells (iPSCs) – an adult cell that has been changed or reprogrammed so that it can then be changed into virtually any other cell in the body.

CIRM’s mission is to accelerate stem cell treatments to patients with unmet medical needs and Alzheimer’s – which has no cure and no effective long-term treatments – clearly represents an unmet medical need.

Another project approved by the Board is run by a team at Children’s Hospital Oakland Research Institute (CHORI). They got almost $4.5 million for their research helping people with sickle cell anemia, an inherited blood disorder that causes intense pain, and can result in strokes and organ damage. Sickle cell affects around 100,000 people in the US, mostly African Americans.

The CHORI team wants to use a new gene-editing tool called CRISPR-Cas9 to develop a method of editing the defective gene that causes Sickle Cell, creating a healthy, sickle-free blood supply for patients.

Right now, the only effective long-term treatment for sickle cell disease is a bone marrow transplant, but that requires a patient to have a matched donor – something that is hard to find. Even with a perfect donor the procedure can be risky, carrying with it potentially life-threatening complications. Using the patient’s own blood stem cells to create a therapy would remove those complications and even make it possible to talk about curing the disease.

While damaged cartilage isn’t life-threatening it does have huge quality of life implications for millions of people. Untreated cartilage damage can, over time lead to the degeneration of the joint, arthritis and chronic pain. Researchers at the University of Southern California (USC) were awarded $2.5 million to develop an off-the-shelf stem cell product that could be used to repair the damage.

The fourth and final award ($2.09 million) went to Ankasa Regenerative Therapeutics, which hopes to create a stem cell therapy for osteonecrosis. This is a painful, progressive disease caused by insufficient blood flow to the bones. Eventually the bones start to rot and die.

As Jonathan Thomas, Chair of the CIRM Board, said in a news release, we are hoping this is just the next step for these programs on their way to helping patients:

“These Translational Awards highlight our goal of creating a pipeline of projects, moving through different stages of research with an ultimate goal of a successful treatment. We are hopeful these projects will be able to use our newly created Stem Cell Center to speed up their progress and pave the way for approval by the FDA for a clinical trial in the next few years.”

A new and improved method for making healthy heart tissue is here

Scientists from the Gladstone Institutes have done it again. They’ve made a better and faster way of generating healthy heart tissue in mice with damaged hearts. With further advancements, their findings could potentially be translated into a new way of treating heart failure in patients.

Previously, the Gladstone team discovered that they could transform scar tissue in the damaged hearts of mice into healthy, beating heart muscle cells by a process called direct reprogramming. The team found that turning on three transcription factors, Gata4, Mef2c and Tbx5 (collectively called GMT), in the damaged hearts of mice activated heart genes that turned scar tissue cells, also known as cardiac fibroblasts, into beating heart cells or cardiomyocytes.

Their GMT direct cardiac reprogramming technology was only able to turn 10 percent of cardiac fibroblasts into cardiomyocytes in mice over the period of six to eight week. In their new CIRM-funded study published in Circulation, they improved upon their original reprogramming method by identifying two chemicals that improved the efficiency of making new heart cells. Not only were they able to create eight times the number of beating cardiomyocytes from mouse cardiac fibroblasts, but they were also able to speed up the reprogramming process to a period of just one week.

To find these chemicals, they screened a library of 5,500 small molecules. The chemicals that looked most promising for cardiac reprogramming were inhibitors of the TGF-β and WNT signaling pathways. The importance of these chemicals was explained in a Gladstone news release:

“The first chemical inhibits a growth factor that helps cells grow and divide and is important for repairing tissue after injury. The second chemical inhibits an important pathway that regulates heart development. By combining the two chemicals with GMT, the researchers successfully regenerated heart muscle and greatly improved heart function in mice that had suffered a heart attack.”

Senior author on the study, Deepak Srivastava, further explained:

“While our original process for direct cardiac reprogramming with GMT has been promising, it could be more efficient. With our screen, we discovered that chemically inhibiting two biological pathways active in embryonic formation improves the speed, quantity, and quality of the heart cells produced from our original process.”

Encouraged by their studies in mice, the scientists also tested their new and improved direct reprogramming method on human cells. Previously they found that while the same GMT transcription factors could reprogram human cardiac fibroblasts into cardiomyocytes, a combination of seven factors was required to make quality cardiomyocytes comparable to those seen in mice. But with the addition of the two inhibitors, they were able to reduce the number of reprogramming factors from seven to four, which included the GMT factors and one additional factor called Myocardin. These four factors plus the two chemical inhibitors were capable of reprograming human cardiac fibroblasts into beating heart cells.

With heart failure affecting more than 20 million people globally, the need for new therapies that can regenerate the heart is pressing. The Gladstone team is hoping to advance their research to a point where it could be tested in human patients with heart failure. First author on the study, Tamer Mohamed, concluded:

“Heart failure afflicts many people worldwide, and we still do not have an effective treatment for patients suffering from this disease. With our enhanced method of direct cardiac reprogramming, we hope to combine gene therapy with drugs to create better treatments for patients suffering from this devastating disease.”

Tamer Mohamed and Deepak Srivastava, Gladstone Institutes

Tamer Mohamed and Deepak Srivastava. Photo courtesy of Chris Goodfellow, Gladstone Institutes


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Throwback Thursday: Progress to a Cure for Type 1 Diabetes

Welcome back to our “Throwback Thursday” series on the Stem Cellar. Over the years, we’ve accumulated an arsenal of valuable stem cell stories on our blog. Some of these stories represent crucial advances towards stem cell-based cures for serious diseases and deserve a second look.

novemberawarenessmonthThis week in honor of Diabetes Awareness Month, we are featuring type 1 diabetes (T1D), a chronic disease that destroys the insulin-producing beta cells in your pancreas. Without these important cells, patients cannot maintain the proper levels of glucose, a fancy name for sugar, in their blood and are at risk for many complications including heart disease, blindness, and even death.

Cell replacement therapy is evolving into an attractive option for patients with T1D. Replacing lost beta cells in the pancreas is a more permanent and less burdensome solution than the daily insulin shots (or insulin pumps) that many T1D patients currently take.

So let’s take a look at the past year’s advances in stem cell research for diabetes.

Making Insulin-Producing Cells from Stem Cells and Skin

This year, there were a lot of exciting studies that improved upon previous methods for generating pancreatic beta cells in a dish. Here’s a brief recap of a few of the studies we covered on our blog:

  • Make pancreatic cells from stem cells. Scientists from the Washington University School of Medicine in St. Louis and the Harvard Stem Cell Institute developed a method that makes beta cells from T1D patient-derived induced pluripotent stem cells (iPSCs) that behave very similarly to true beta cells both in a dish and when transplanted into diabetic mice. Their discovery has the potential to offer personalized stem cell treatments for patients with T1D in the near future and the authors of the study predicted that their technology could be ready to test in humans in the next three to five years.
  • Making functional pancreatic cells from skin. Scientists from the Gladstone Institutes used a technique called direct reprogramming to turn human skin cells directly into pancreatic beta cells without having to go all the way back to a pluripotent stem cell state. The pancreatic cells looked and acted like the real thing in a dish (they were able to secrete insulin when exposed to glucose), and they functioned normally when transplanted into diabetic mice. This study is exciting because it offers a new and more efficient method to make functioning human beta cells in mass quantities.

    Functioning human pancreatic cells after they’ve been transplanted into a mouse. (Image: Saiyong Zhu, Gladstone)

    Functioning human pancreatic cells after they’ve been transplanted into a mouse. (Image: Saiyong Zhu, Gladstone)

  • Challenges of stem cell-derived diabetes treatments. At this year’s Ogawa-Yamanaka Stem Cell Award ceremony Douglas Melton, a well-renowned diabetes researcher from Harvard, spoke about the main challenges for developing stem cell-derived diabetes treatments. The first is the need for better control over the methods that make beta cells from stem cells. The second was finding ways to make large quantities of beta cells for human transplantation. The last was finding ways to prevent a patient’s immune system from rejecting transplanted beta cells. Melton and other scientists are already working on improving techniques to make more beta cells from stem cells. As for preventing transplanted beta cells from being attacked by the patient’s immune system, Melton described two possibilities: using an encapsulation device or biological protection to mask the transplanted cells from an attack.

Progress to a Cure: Clinical Trials for Type 1 Diabetes

Speaking of encapsulation devices, CIRM is funding a Phase I clinical trial sponsored by a San Diego-based company called ViaCyte that’s hoping to develop a stem cell-based cure for patients with T1D. The treatment involves placing a small encapsulated device containing stem cell-derived pancreatic precursor cells under the skin of T1D patients. Once implanted, these precursor cells should develop into pancreatic beta cells that can secrete insulin into the patient’s blood stream. The goal of this trial is first to make sure the treatment is safe for patients and second to see if it’s effective in improving a patient’s ability to regulate their blood sugar levels.

To learn more about this exciting clinical trial, watch this fun video made by Youreka Science.

ViaCyte is still waiting on results for their Phase 1 clinical trial, but in the meantime, they are developing a modified version of their original device for T1D called PEC-Direct. This device also contains pancreatic precursor cells but it’s been designed in a way that allows the patient’s blood vessels to make direct connections to the cells inside the device. This vascularization process hopefully will improve the survival and function of the insulin producing beta cells inside the device. This study, which is in the last stage of research before clinical trials, is also being funded by CIRM, and we are excited to hear news about its progress next year.

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

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


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How research on a rare disease turned into a faster way to make stem cells

Forest Gump. (Paramount Pictures)

Forest Gump. (Paramount Pictures)

If Forest Gump were a scientist, I’d like to think he would have said his iconic line a little differently. Dr. Gump would have said, “scientific research is like a box of chocolates – you never know what you’re gonna get.”

A new CIRM-funded study coming out of the Gladstone Institutes certainly proves this point. Published yesterday in the Proceedings of the National Academy of Sciences, the study found that a specific genetic mutation known to cause a rare disease called fibrodysplasia ossificans progressiva (FOP) makes it easier to reprogram adult skin cells into induced pluripotent stem cells (iPSCs).

Shinya Yamanaka received the Nobel Prize in medicine in 2012 for his seminal discovery of the iPSC technology, which enabled scientists to generate patient specific pluripotent stem cell lines from adult cells like skin and blood. These iPSC lines are useful for modeling disease in a dish, identifying new therapeutic drugs, and potentially for clinical applications in patients. However, one of the rate-limiting steps to this technology is the inefficient process of making iPSCs.

Yamanaka, a senior investigator at Gladstone, knows this problem all too well. In a Gladstone news release he commented, “inefficiency in creating iPSCs is a major roadblock toward applying this technology to biomedicine. Our study identified a surprising way to increase the number of iPSCs that we can generate.”

So how did Yamanaka and his colleagues discover this new trick for making iPSCs more efficiently? Originally, their intentions were to model a rare genetic disease called FOP. It’s commonly known as “stone man syndrome” because the disease converts normal muscle and connective tissue into bone either spontaneously or spurred by injury. Bone growth begins at a young age starting at the neck and progressively moving down the body. Because there is no treatment or cure, patients typically have a lifespan of only 40 years.

The Gladstone team wanted to understand this rare disease better by modeling it in a dish using iPSCs generated from patients with FOP. These patients had a genetic mutation in the ACVR1 gene, which plays an important role in the development of the embryo. FOP patients have a mutant form of ACVR1 that overstimulates this developmental pathway and boosts the activity of a protein called BMP (bone morphogenic protein). When BMP signaling is ramped up, they discovered that they could produce significantly more iPSCs from the skin cells of FOP patients compared to normal, healthy skin cells.

First author on the study, Yohei Hayashi, explained their hypothesis for why this mutation makes it easier to generate iPSCs:

“Originally, we wanted to establish a disease model for FOP that might help us understand how specific gene mutations affect bone formation. We were surprised to learn that cells from patients with FOP reprogrammed much more efficiently than cells from healthy patients. We think this may be because the same pathway that causes bone cells to proliferate also helps stem cells to regenerate.”

To be sure that enhanced BMP signaling caused by the ACVR1 mutation was the key to generating more iPSCs, they blocked this signal and discovered that much fewer iPSCs were made from FOP patient skin cells.

Senior Investigator Bruce Conklin, who was a co-author on this study, succinctly summarized the importance of their findings:

“This is the first reported case showing that a naturally occurring genetic mutation improves the efficiency of iPSC generation. Creating iPSCs from patient cells carrying genetic mutations is not only useful for disease modeling, but can also offer new insights into the reprogramming process.”

Gladstone investigators Bruce Conklin and Shinya Yamanaka. (Photo courtesy of Chris Goodfellow, Gladstone Institutes)

Gladstone investigators Bruce Conklin and Shinya Yamanaka. (Photo courtesy of Chris Goodfellow, Gladstone Institutes)