CIRM weekly stem cell roundup: minibrain model of childhood disease; new immune insights; patient throws out 1st pitch

New human Mini-brain model of devastating childhood disease.
The eradication of Aicardi-Goutieres Syndrome (AGS) can’t come soon enough. This rare but terrible inherited disease causes the immune system to attack the brain. The condition leads to microcephaly (an abnormal small head and brain size), muscle spasms, vision problems and joint stiffness during infancy. Death or a persistent comatose state is common by early childhood. There is no cure.

Though animal models that mimic AGS symptoms are helpful, they don’t reflect the human disease closely enough to provide researchers with a deeper understanding of the mechanisms of the disease. But CIRM-funded research published this week may be a game changer for opening up new therapeutic strategies for the children and their families that are suffering from AGS.

Organoid mini-brains are clusters of cultured cells self-organized into miniature replicas of organs. Image courtesy of Cleber A. Trujillo, UC San Diego.

To get a clearer human picture of the disease, Dr. Alysson Muotri of UC San Diego and his team generated AGS patient-derived induced pluripotent stem cells (iPSCs). These iPSCs were then grown into “mini-brains” in a lab dish. As described in Cell Stem Cell, their examination of the mini-brains revealed an excess of chromosomal DNA in the cells. This abnormal build up causes various toxic effects on the nerve cells in the mini-brains which, according to Muotri, had the hallmarks of AGS in patients:

“These models seemed to mirror the development and progression of AGS in a developing fetus,” said Muotri in a press release. “It was cell death and reduction when neural development should be rising.”

In turns out that the excess DNA wasn’t just a bunch of random sequences but instead most came from so-called LINE1 (L1) retroelements. These repetitive DNA sequences can “jump” in and out of DNA chromosomes and are thought to be remnants of ancient viruses in the human genome. And it turns out the cell death in the mini-brains was caused by the immune system’s anti-viral response to these L1 retroelements. First author Charles Thomas explained why researchers may have missed this in their mouse models:

“We uncovered a novel and fundamental mechanism, where chronic response to L1 elements can negatively impact human neurodevelopment. This mechanism seems human-specific. We don’t see this in the mouse.”

The team went on to test the anti-retroviral effects of HIV drugs on their AGS models. Sure enough, the drugs decreased the amount of L1 DNA and cell growth rebounded in the mini-brains. The beauty of using already approved drugs is that the route to clinical trials is much faster and in fact a European trial is currently underway.

For more details, watch this video interview with Dr. Muotri:

New findings about immune cell development may open door to new cancer treatments
For those of you who suffer with seasonal allergies, you can blame your sniffling and sneezing on an overreaction by mast cells. These white blood cells help jump start the immune system by releasing histamines which makes blood vessels leaky allowing other immune cells to join the battle to fight disease or infection. Certain harmless allergens like pollen are mistaken as dangerous and can also cause histamine release which triggers tearing and sneezing.

Mast cells in lab dish. Image: Wikipedia.

Dysfunction of mast cells are also involved in some blood cancers. And up until now, it was thought a protein called stem cell factor played the key role in the development of blood stem cells into mast cells. But research reported this week by researchers at Karolinska Institute and Uppsala University found cracks in that previous hypothesis. Their findings published in Blood could open the door to new cancer therapies.

The researchers examine the effects of the anticancer drug Glivec – which blocks the function of stem cell factor – on mast cells in patients with a form of leukemia. Although the number of mature mast cells were reduced by the drug, the number of progenitor mast cells were not. The progenitors are akin to teenagers in that they’re at an intermediate stage of development, more specialized than stem cells but not quite mast cells. The team went on to confirm that stem cell factor was not required for the mast cell progenitors to survive, multiply and mature. Instead, their work identified two other growth factors, interleukin 3 and 6, as important for mast cell development.

In a press release, lead author Joakim Dahlin, explained how these new insights could lead to new therapies:

“The study increases our understanding of how mast cells are formed and could be important in the development of new therapies, for example for mastocytosis for which treatment with imatinib/Glivec is not effective. One hypothesis that we will now test is whether interleukin 3 can be a new target in the treatment of mast cell-driven diseases.”

Patient in CIRM-funded trial regains use of arms, hands and fingers will throw 1st pitch in MLB game.
We end this week with some heart-warming news from Asterias Biotherapeutics. You avid Stem Cellar readers will remember our story about Lucas Lindner several weeks back. Lucas was paralyzed from the neck down after a terrible car accident. Shortly after the accident, in June of 2016, he enrolled in Asterias’ CIRM-funded trial testing an embryonic stem cell-based therapy to treat his injury. And this Sunday, August 13th, we’re excited to report that due to regaining the use of his arms, hands and fingers since the treatment, he will throw out the first pitch of a Major League Baseball game in Milwaukee. Congrats to Lucas!

For more about Lucas’ story, watch this video produced by Asterias Biotherapeutics:

Making brain stem cells act more like salmon than bloodhounds

Like salmon swimming against a river current, brain stem cells can travel against their normal migration stream with the help of electrical stimuli, so says CIRM-funded research published this week in Stem Cell Reports. The research, carried out by a team of UC Davis scientists, could one day provide a means for guiding brain stem cells, or neural stem cells (NSCs), to sites of disease or injury in the brain.

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Human neural stem cells (green) guided by electrical stimulation migrated to and colonized the subventricular zone of rats’ brains. This image was taken three weeks after stimulation. Image: Jun-Feng Feng/UC DAVIS, Sacramento and Ren Ji Hospital, Shanghai.

NSCs are a key ingredient in the development of therapies that aim to repair damaged areas of the brain. Given the incredibly intricate structure of nerve connections, targeting these stem cells to their intended location is a big challenge for therapy development. One obstacle is mobility. Although resident NSCs can travel long distances within the brain, the navigation abilities of transplanted NSCs gets disrupted and becomes very limited.

In earlier work, the research team had shown that electrical currents could nudge NSCs to move in a petri dish (watch team lead Dr. Min Zhao describe this earlier work in the 30 second video below) so they wanted to see if this technique was possible within the brains of living rats. By nature, NSCs are more like bloodhounds than salmon, moving from one location to another by sensing an increasing gradient of chemicals within the brain. In this study, the researchers transplanted human NSCs in the middle of such a such gradient, called the rostral migration stream, that normally guides the cells to the olfactory bulb, the area responsible for our sense of smell.

Electrodes were implanted into the brains of the rats and an electrical current flowing in the opposite direction of the rostral migration stream was applied. This stimulus caused the NSCs to march in the direction of the electrical current. Even at three and four weeks after the stimulation, the altered movement of the NSCs continued. And there was indication that the cells were specializing into various types of brain cells, an important observation for any cell therapy meant to replace diseased cells.

The Scientist interviewed Dr. Alan Trounson, of the Hudson Institute of Australia, who was not involved in study, to get his take on the results:

“This is the first study I’ve seen where stimulation is done with electrodes in the brain and has been convincing about changing the natural flow of cells so they move in the opposite direction. The technique has strong possibilities for applications because the team has shown you can move cells, and you could potentially move them into seriously affected brain areas.”

Though it’s an intriguing proof-of-concept, much works remains to show this technique is plausible in the clinic. Toward that goal, the team has plans to repeat the studies in primates using a less invasive method that transmits the electrical signals through the skull.

Scientist grow diseased brain cells in bulk to study Alzheimer’s and Parkinson’s disease

Daily trips to the local grocery store have become a thing of the past for many with the rise of wholesale stores like Costco and online giants like Amazon. Buying in bulk is attractive for people who lead busy lives, have large families, or just love having endless pairs of clean socks.

Scientists who study neurodegenerative diseases like Alzheimer’s and Parkinson’s use disease-in-a-dish models that are much like the daily visits to the nearby Safeway. They can make diseased brain cells, or neurons, from human pluripotent stem cells and study them in the lab. But often, they can’t generate large enough quantities of cells to do important experiments like test new drugs or develop diagnostic platforms to identify disease at an earlier age.

What scientists need is a Costco for brain cells, a source that can make diseased brain cells in bulk. Such a method would open a new avenue of research into what causes neurodegeneration and how the aging process affects its progression.

This week, this need was answered. A team of researchers from Lund University in Sweden developed a method that can efficiently generate neurons from patients with a range of neurodegenerative diseases including Parkinson’s, Huntington’s and Alzheimer’s disease. The study was published in EMBO Molecular Medicine and was led by senior author Dr. Malin Parmar.

Diseased neurons made by the Lund University team. (Photo, Kennet Ruona)

Parmar and her team took an alternative approach to making their neurons. Their technology involves converting human skin cells into neurons without reprogramming the skin cells back to a pluripotent stem cell state first. This process is called “direct conversion” and is considered an effective shortcut for generating mature cells like neurons in a dish. Direct conversion of skin cells into neurons was first published by Dr. Marius Wernig, a CIRM-grantee and professor at Stanford University.

There is also scientific evidence suggesting that reprogramming patient cells back to a pluripotent state wipes out the effects of aging in those cells and has a Benjamin Button-like effect on the resulting neurons. By directly converting patient skin cells into neurons, many of these aging “signatures” are retained and the resulting neurons are more representative of the aging brain.

So how did they make brain cells in bulk? Parmar explained their method in a Lund University news release,

Malin Parmar

“Primarily, we inhibited a protein, REST, involved in establishing identity in cells that are not nerve cells. After limiting this protein’s impact in the cells during the conversion process, we’ve seen completely different results.”

 

Besides blocking REST, the team also turned on the production of two proteins, Ascl1 and Brn2, that are important for the development of neurons. This combination of activating pro-neural genes and silencing anti-neural genes was successful at converting skin cells into neurons on a large scale. Parmar further explained,

“We’ve been playing around with changing the dosage of the other components in the previous method, which also proved effective. Overall, the efficiency is remarkable. We can now generate almost unlimited amounts of neurons from one skin biopsy.”

As mentioned previously, this technology is valuable because it provides better brain disease models for scientists to study and to screen for new drugs that could treat or delay disease onset. Additionally, scientists can study the effects of the aging in the brain at different stages of neurodegeneration. Aging is a well-known risk factor for many neurodegenerative diseases, especially Alzheimer’s, so the ability to make large quantities of brain cells from elderly Alzheimer’s patients will unlock new clues into how age influences disease.

Co-author Dr. Johan Jakobsson concluded,

Johan Jakobsson

“This takes us one step closer to reality, as we can now look inside the human neurons and see what goes on inside the cell in these diseases. If all goes well, this could fundamentally change the field of research, as it helps us better understand the real mechanisms of the disease. We believe that many laboratories around the world would like to start testing on these cells to get closer to the diseases.”

For more on this study, check out this short video provided by Lund University.

Stories that caught our eye: An antibody that could make stem cell research safer; scientists prepare for clinical trial for Parkinson’s disease; and the stem cell scientist running for Congress

Antibody to make stem cells safer:

There is an old Chinese proverb that states: ‘What seems like a blessing could be a curse’. In some ways that proverb could apply to stem cells. For example, pluripotent stem cells have the extraordinary ability to turn into many other kinds of cells, giving researchers a tool to repair damaged organs and tissues. But that same ability to turn into other kinds of cells means that a pluripotent stem cell could also turn into a cancerous one, endangering someone’s life.

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Researchers at the A*STAR Bioprocessing Technology Institute: Photo courtesy A*STAR

Now researchers at the Agency for Science, Technology and Research (A*STAR) in Singapore may have found a way to stop that happening.

When you change, or differentiate, stem cells into other kinds of cells there will always be some of the original material that didn’t make the transformation. Those cells could turn into tumors called teratomas. Scientists have long sought for a way to identify pluripotent cells that haven’t differentiated, without harming the ones that have.

The team at A*STAR injected mice with embryonic stem cells to generate antibodies. They then tested the ability of the different antibodies to destroy pluripotent stem cells. They found one, they called A1, that did just that; killing pluripotent cells but leaving other cells unharmed.

Further study showed that A1 worked by attaching itself to specific molecules that are only found on the surface of pluripotent cells.

In an article on Phys.Org Andre Choo, the leader of the team, says this gives them a tool to get rid of the undifferentiated cells that could potentially cause problems:

“That was quite exciting because it now gives us a view of the mechanism that is responsible for the cell-killing effect.”

Reviving hope for Parkinson’s patients:

In the 1980’s and 1990’s scientists transplanted fetal tissue into the brains of people with Parkinson’s disease. They hoped the cells in the tissue would replace the dopamine-producing cells destroyed by Parkinson’s, and stop the progression of the disease.

For some patients the transplants worked well. For some they produced unwanted side effects. But for most they had little discernible effect. The disappointing results pretty much brought the field to a halt for more than a decade.

But now researchers are getting ready to try again, and a news story on NPR explained why they think things could turn out differently this time.

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Viviane Tabar, MD; Photo courtesy Memorial Sloan Kettering Cancer Center

Viviane Tabar, a stem cell researcher at Memorial Sloan Kettering Cancer Center in New York, says in the past the transplanted tissue contained a mixture of cells:

“What you were placing in the patient was just a soup of brain. It did not have only the dopamine neurons, which exist in the tissue, but also several different types of cells.”

This time Tabar and her husband, Lorenz Studer, are using only cells that have been turned into the kind of cell destroyed by the disease. She says that will, hopefully, make all the difference:

“So you are confident that everything you are putting in the patient’s brain will consist of  the right type of cell.”

Tabar and Studer are now ready to apply to the Food and Drug Administration (FDA) for permission to try their approach out in a clinical trial. They hope that could start as early as next year.

Hans runs for Congress:

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Hans Keirstead: Photo courtesy Orange County Register

Hans Keirstead is a name familiar to many in the stem cell field. Now it could become familiar to a lot of people in the political arena too, because Keirstead has announced he’s planning to run for Congress.

Keirstead is considered by some to be a pioneer in stem cell research. A CIRM grant helped him develop a treatment for spinal cord injury.  That work is now in a clinical trial being run by Asterias. We reported on encouraging results from that trial earlier this week.

Over the years the companies he has founded – focused on ovarian, skin and brain cancer – have made him millions of dollars.

Now he says it’s time to turn his sights to a different stage, Congress. Keirstead has announced he is going to challenge 18-term Orange County Republican Dana Rohrabacher.

In an article in the Los Angeles Times, Keirstead says his science and business acumen will prove important assets in his bid for the seat:

“I’ve come to realize more acutely than ever before the deficits in Congress and how my profile can actually benefit Congress. I’d like to do what I’m doing but on a larger stage — and I think Congress provides that, provides a forum for doing the greater good.”

Stem cell repair of birth defect during pregnancy possible, rodent study shows

As far-fetched as it may sound, performing prenatal surgery on a fetus still growing inside its mother’s womb is actually possible. This specialized procedure is done to repair birth defects like spina bifida, in which a baby’s back bones don’t form properly around the spinal cord. This opening in the spine that leads to excess spinal fluid and leaves spinal cord nerve cells unprotected from the surrounding tissue.  These abnormalities can lead to brain damage, paralysis and loss of bladder control.

Although prenatal surgery to close up the defect can reduce future neurological problems in the child’s life, there is an increased danger of significant complications including preterm birth, separation of the placenta from the uterus and premature breaking on the amniotic membrane (ie breaking the mother’s water).

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Microscopy image of iSkin, three-dimensional cultured skin derived from human iPSCs. Credit: Kazuhiro Kajiwara.

A research team at Japan’s National Research Institute for Child Health and Development is trying to overcome these problems by developing a less invasive prenatal therapy for spina bifida using stem cells. And this week, they published a Stem Cell Reports study that shows encouraging preclinical results in rodents.

The most severe and common form of spina bifida called myelomeningocele usually leads to the formation of a fluid-filled bulge protruding from a newborn’s back. The team’s therapeutic approach is to graft 3D layers of stem cell-derived skin early in the pregnancy to prevent the bulge from forming in the first place. This minimally invasive procedure would hopefully be less risky than the surgical approach.

To demonstrate a proof of concept for this approach, skin graft experiments were performed on fetal rats that had myelomeningocele-like symptoms induced by the hormone retinoic acid. Human amniotic fluid cells collected from two pregnancies with severe fetal defects were used to derived human iPSCs which were then specialized into skin cells. Over a 14-week period – a timeline short enough to allow the eventual human procedure to be performed within the 28th to 29th week of pregnancy – the cells were grown into 3D layers they call, “iSkin”.

The iSkin grafts were transplanted in 20 fetal rats through a small cut into the wall of the uterus. At birth, the myelomeningocele defect in four rats was completely covered and partially covered in another eight rats. It’s encouraging to note that no tumors formed from the skin transplants, a concern when dealing with iPSC-derived cell therapies. In press release, team lead Dr. Akihiro Umezawa spoke about the promise of this approach but also the work that still lies ahead:

“We are encouraged by our results and believe that our fetal stem cell therapy has great potential to become a novel treatment for myelomeningocele. However, additional studies in larger animals are needed to demonstrate that our fetal stem cell therapy safely promotes long-term skin regeneration and neurological improvement.”

New stem cell technique gives brain support cells a starring role

Gage et al

The Salk team. From left: Krishna Vadodaria, Lynne Moore, Carol Marchetto, Arianna Mei, Fred H. Gage, Callie Fredlender, Ruth Keithley, Ana Diniz Mendes. Photo courtesy Salk Institute

Astrocytes are some of the most common cells in the brain and central nervous system but they often get overlooked because they play a supporting role to the more glamorous neurons (even though they outnumber them around 50 to 1). But a new way of growing those astrocytes outside the brain could help pave the way for improved treatments for stroke, Alzheimer’s and other neurological problems.

Astrocytes – which get their name because of their star shape (Astron – Greek for “star” and “kyttaron” meaning cell) – have a number of key functions in the brain. They provide physical and metabolic support for neurons; they help supply energy and fuel to neurons; and they help with detoxification and injury repair, particularly in terms of reducing inflammation.

Studying these astrocytes in the lab has not been easy, however, because existing methods of producing them have been slow, cumbersome and not altogether effective at replicating their many functions.

Finding a better way

Now a team at the Salk Institute, led by CIRM-funded Professor Fred “Rusty” Gage, has developed a way of using stem cells to create astrocytes that is faster and more effective.

Their work is published in the journal Stem Cell Reports. In a news release, Gage says this is an important discovery:

“This work represents a big leap forward in our ability to model neurological disorders in a dish. Because inflammation is the common denominator in many brain disorders, better understanding astrocytes and their interactions with other cell types in the brain could provide important clues into what goes wrong in disease.”

Stylized microscopy image of an astrocyte (red) and neuron (green). (Salk Institute)

In a step by step process the Salk team used a series of chemicals, called growth factors, to help coax stem cells into becoming, first, generic brain cells, and ultimately astrocytes. These astrocytes not only behaved like the ones in our brain do, but they also have a particularly sensitive response to inflammation. This gives the team a powerful tool in helping develop new treatment to disorders of the brain.

But wait, there’s more!

As if that wasn’t enough, the researchers then used the same technique to create astrocytes from induced pluripotent stem cells (iPSCs) – adult cells, such as skin, that have been re-engineered to have the ability to turn into any other kind of cell in the body. Those man-made astrocytes also showed the same characteristics as natural ones do.

Krishna Vadodaria, one of the lead authors on the paper, says having these iPSC-created astrocytes gives them a completely new tool to help explore brain development and disease, and hopefully develop new treatments for those diseases.

“The exciting thing about using iPSCs is that if we get tissue samples from people with diseases like multiple sclerosis, Alzheimer’s or depression, we will be able to study how their astrocytes behave, and how they interact with neurons.”

Stem cell stories that caught our eye: brains, brains and more brains!

This week we bring you three separate stories about the brain. Two are exciting new advances that use stem cells to understand the brain and the third is plain creepy.

Bioengineering better brains. Lab grown mini-brains got an upgrade thanks to a study published this week in Nature Biotechnology. Mini-brains are tiny 3D organs that harbor similar cell types and structures found in the human brain. They are made from pluripotent stem cells cultured in laboratory bioreactors that allow these cells to mature into brain tissue in the span of a month.

The brain organoid technology was first published back in 2013 by Austrian scientists Jürgen Knoblich and Madeline Lancaster. They used mini-brains to study human brain development and a model a birth defect called microcephaly, which causes abnormally small heads in babies. Mini-brains filled a void for scientists desperate for better, more relevant models of human brain development. But the technology had issues with consistency and produced organoids that varied in size, structure and cell type.

Cross-section of a mini-brain. (Madeline Lancaster/MRC-LMB)

Fast forward four years and the same team of scientists has improved upon their original method by adding a bioengineering technique that will generate more consistent mini-brains. Instead of relying on the stem cells to organize themselves into the proper structures in the brain, the team developed a biological scaffold made of microfilaments that guides the growth and development of stem cells into organoids. They called these “engineered cerebral organoids” or enCORs for short.

In a news feature on IMBA, Jürgen Knoblich explained that enCORs are more reproducible and representative of the brain’s architecture, thus making them more effective models for neurological and neurodevelopmental disorders.

“An important hallmark of the bioengineered organoids is their increased surface to volume ratio. Because of their improved tissue architecture, enCORs can allow for the study of a broader array of neurological diseases where neuronal positioning is thought to be affected, including lissencephaly (smooth brain), epilepsy, and even autism and schizophrenia.”

Salk team finds genetic links between brain’s immune cells and neurological disorders. (Todd Dubnicoff)

Dysfunction of brain cells called microglia have been implicated in a wide range of neurologic disorders like Alzheimer’s, Parkinson’s, Huntington’s, autism and schizophrenia. But a detailed examination of these cells has proved difficult because they don’t grow well in lab dishes. And attempts to grow microglia from stem cells is hampered by the fact that the cell type hasn’t been characterized enough for researchers to know how to distinguish it from related cell types found in the blood.

By performing an extensive analysis of microglia gene activity, Salk Institute scientists have now pinpointed genetic links between these cells and neurological disease. These discoveries also demonstrate the importance of the microglia’s environment within the brain to maintain its identity. The study results were reported in Science.

Microglia are important immune cells in the brain. They are related to macrophages which are white blood cells that roam through the body via the circulatory system and gobble up damaged or dying cells as well as foreign invaders. Microglia also perform those duties in the brain and use their eating function to trim away faulty or damage nerve connections.

To study a direct source of microglia, the team worked with neurosurgeons to obtain small samples of brain tissue from patients undergoing surgery for epilepsy, a tumor or stroke. Microglia were isolated from healthy regions of brain tissue that were incidentally removed along with damaged or diseased brain tissue.

Salk and UC San Diego scientists conducted a vast survey of microglia (pictured here), revealing links to neurodegenerative diseases and psychiatric illnesses. (Image: Nicole Coufal)

A portion of the isolated microglia were immediately processed to take a snap shot of gene activity. The researchers found that hundreds of genes in the microglia had much higher activities compared to those same genes in macrophages. But when the microglia were transferred to petri dishes, gene activity in general dropped. In fact, within six hours of tissue collection, the activity of over 2000 genes in the cells had dropped significantly. This result suggests the microglial rely on signals in the brain to stimulate their gene activity and may explain why they don’t grow well once removed from that environment into lab dishes.

Of the hundreds of genes whose activity were boosted in microglia, the researchers tracked down several that were linked to several neurological disorders. Dr. Nicole Coufal summarized these results and their implications in a Salk press release:

“A really high proportion of genes linked to multiple sclerosis, Parkinson’s and schizophrenia are much more highly expressed in microglia than the rest of the brain. That suggests there’s some kind of link between microglia and the diseases.”

Future studies are needed to explain the exact nature of this link. But with these molecular descriptions of microglia gene activity now in hand, the researchers are in a better position to study microglia’s role in disease.

A stem cell trial to bring back the dead, brain-dead that is. A somewhat creepy stem cell story resurfaced in the news this week. A company called Bioquark in Philadelphia is attempting to bring brain-dead patients back to life by injecting adult stem cells into their spinal cords in combination with other treatments that include protein blend injections, electrical nerve stimulation and laser therapy. The hope is that this combination stem cell therapy will generate new neurons that can reestablish lost connections in the brain and bring it back to life.

Abstract image of a neuron. (Dom Smith/STAT)

You might wonder why the company is trying multiple different treatments simultaneously. In a conversation with STAT news, Bioquark CEO Ira Pastor explained,

“It’s our contention that there’s no single magic bullet for this, so to start with a single magic bullet makes no sense. Hence why we have to take a different approach.”

Bioquark is planning to relaunch a clinical trial testing its combination therapy in Latin America sometime this year. The company previously attempted to launch its first trial in India back in April of 2016, but it never got off the ground because it failed to get clearance from India’s Drug Controller General.

STATnews staff writer Kate Sheridan called the trial “controversial” and raised questions about how it would impact patients and their families.

“How do researchers complete trial paperwork when the person participating is, legally, dead? If the person did regain brain activity, what kind of functional abilities would he or she have? Are families getting their hopes up for an incredibly long-shot cure?”

Scientists also have questions mainly about whether this treatment will actually work or is just a shot in the dark. Adding to the uncertainty is the fact that Bioquark has no preclinical evidence that its combination treatment is effective in animal models. The STAT piece details how the treatments have been tested individually for other conditions such as stroke and coma, but not in brain-dead patients. To further complicate things, there is no consensus on how to define brain death in patients, so patient improvements observed during the trial could be unrelated to the treatment.

STAT asked expert doctors in the field whether Bioquark’s strategy was feasible. Orthopedic surgeon Dr. Ed Cooper said that there’s no way electric stimulation would work, pointing out that the technique requires a functioning brain stem which brain-dead patients don’t have. Pediatric surgeon Dr. Charles Cox, who works on a stem cell treatment for traumatic brain injury and is unrelated to Bioquark, commented, “it’s not the absolute craziest thing I’ve ever heard, but I think the probability of that working is next to zero.”

But Pastor seems immune to the skepticism and naysayers.

“I give us a pretty good chance. I just think it’s a matter of putting it all together and getting the right people and the right minds on it.”

Stem cell stories that caught our eye: update on Capricor’s heart attack trial; lithium on the brain; and how stem cells do math

Capricor ALLSTARToday our partners Capricor Therapeutics announced that its stem cell therapy for patients who have experienced a large heart attack is unlikely to meet one of its key goals, namely reducing the scar size in the heart 12 months after treatment.

The news came after analyzing results from patients at the halfway point of the trial, six months after their treatment in the Phase 2 ALLSTAR clinical trial which CIRM was funding. They found that there was no significant difference in the reduction in scarring on the heart for patients treated with donor heart-derived stem cells, compared to patients given a placebo.

Obviously this is disappointing news for everyone involved, but we know that not all clinical trials are going to be successful. CIRM supported this research because it clearly addressed an unmet medical need and because an earlier Phase 1 study had showed promise in helping prevent decline in heart function after a heart attack.

Yet even with this failure to repeat that promise in this trial,  we learned valuable lessons.

In a news release, Dr. Tim Henry, Director of the Division of Interventional Technologies in the Heart Institute at Cedars-Sinai Medical Center and a Co-Principal Investigator on the trial said:

“We are encouraged to see reductions in left ventricular volume measures in the CAP-1002 treated patients, an important indicator of reverse remodeling of the heart. These findings support the biological activity of CAP-1002.”

Capricor still has a clinical trial using CAP-1002 to treat boys and young men developing heart failure due to Duchenne Muscular Dystrophy (DMD).

Lithium gives up its mood stabilizing secrets

As far back as the late 1800s, doctors have recognized that lithium can help people with mood disorders. For decades, this inexpensive drug has been an effective first line of treatment for bipolar disorder, a condition that causes extreme mood swings. And yet, scientists have never had a good handle on how it works. That is, until this week.

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Evan Snyder

Reporting in the Proceedings of the National Academy of Sciences (PNAS), a research team at Sanford Burnham Prebys Medical Discovery Institute have identified the molecular basis of the lithium’s benefit to bipolar patients.  Team lead Dr. Evan Snyder explained in a press release why his group’s discovery is so important for patients:

“Lithium has been used to treat bipolar disorder for generations, but up until now our lack of knowledge about why the therapy does or does not work for a particular patient led to unnecessary dosing and delayed finding an effective treatment. Further, its side effects are intolerable for many patients, limiting its use and creating an urgent need for more targeted drugs with minimal risks.”

The study, funded in part by CIRM, attempted to understand lithium’s beneficial effects by comparing cells from patient who respond to those who don’t (only about a third of patients are responders). Induced pluripotent stem cells (iPSCs) were generated from both groups of patients and then the cells were specialized into nerve cells that play a role in bipolar disorder. The team took an unbiased approach by looking for differences in proteins between the two sets of cells.

The team zeroed in on a protein called CRMP2 that was much less functional in the cells from the lithium-responsive patients. When lithium was added to these cells the disruption in CRMP2’s activity was fixed. Now that the team has identified the molecular location of lithium’s effects, they can now search for new drugs that do the same thing more effectively and with fewer side effects.

The stem cell: a biological calculator?

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Can stem cells do math?

Stem cells are pretty amazing critters but can they do math? The answer appears to be yes according to a fascinating study published this week in PNAS Proceedings of the National Academy of Sciences.

Stem cells, like all cells, process information from the outside through different receptors that stick out from the cells’ outer membranes like a satellite TV dish. Protein growth factors bind those receptors which trigger a domino effect of protein activity inside the cell, called cell signaling, that transfers the initial receptor signal from one protein to another. Ultimately that cascade leads to the accumulation of specific proteins in the nucleus where they either turn on or off specific genes.

Intuition would tell you that the amount of gene activity in response to the cell signaling should correspond to the amount of protein that gets into the nucleus. And that’s been the prevailing view of scientists. But the current study by a Caltech research team debunks this idea. Using real-time video microscopy filming, the team captured cell signaling in individual cells; in this case they used an immature muscle cell called a myoblast.

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Behavior of cells over time after they have received a Tgf-beta signal. The brightness of the nuclei (circled in red) indicates how much Smad protein is present. This brightness varies from cell to cell, but the ratio of brightness after the signal to before the signal is about the same. Image: Goentoro lab, CalTech.

To their surprise the same amount of growth factor given to different myoblasts cells led to the accumulation of very different amounts of a protein called Smad3 in the cells’ nuclei, as much as a 40-fold difference across the cells. But after some number crunching, they discovered that dividing the amount of Smad3 after growth factor stimulation by the Smad3 amount before growth stimulation was similar in all the cells.

As team lead Dr. Lea Goentoro mentions in a press release, this result has some very important implications for studying human disease:

“Prior to this work, researchers trying to characterize the properties of a tumor might take a slice from it and measure the total amount of Smad in cells. Our results show that to understand these cells one must instead measure the change in Smad over time.”

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Marius Wernig
Photo: Steve Fisch

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

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

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

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