A Tribute to Stem Cells on Valentine’s Day

In case you forgot, today is Valentine’s Day. Whether you love, hate, or could care less about this day, you do have one thing in common with our other readers – you’re a fan of stem cells. (If you’re not, then why are you reading this blog??)

As a tribute to how awesome and important stem cell research is, I offer you a special Valentine’s Day-themed interview with the authors of the CIRM Stem Cellar blog.


What’s your favorite type of stem cell and why? 

Kevin: Embryonic stem cells. Without that one cell none of this work, none of us when you come to think of it, would be possible. Whenever I give talks to the public one of the first things I talk about when explaining what stem cells are and how they work is the cartoon from Piraro, the one featuring the snowmen who look up at snowflakes and say “oh look, stem cells”. For me that captures the power and beauty of these cells. Without them the snowmen/women would not exist. With them all is possible.

Karen: Neural stem cells (NSCs) for the win! First off, they created my brain, so I am truly in their debt. Second, NSCs and I have an intimate relationship. I spent eight years of my life (PhD and postdoc) researching these stem cells in the lab on an epic quest to understand what causes Alzheimer’s and Huntington’s disease. As you can see from the subject matter of my latest blogs (here, here, here), I am pretty stoked to write about NSCs any chance I get.

Microscopic image of a mini brain organoid, showing layered neural tissue and different groups of neural stem cells (in blue, red and magenta) giving rise to neurons (green). Image: Novitch laboratory/UCLA

Todd: Induced pluripotent stem cells (iPSCs) rule! They’re my favorite because they allow researchers to study poorly understood human diseases in a way that just wasn’t possible before iPSCs came on the scene in the late 2000’s. For instance, it’s neither practical nor ethical to study autism by taking cell samples out of the brains of affected children. But with iPSC technology, you can recover cells from an autistic child’s baby teeth after they fall out and grow them into nerve cells in the lab to more directly study the cellular causes of the disorder. I also like the fact that iPSCs are the ultimate in personalized medicine in that you could make a stem cell-based therapy from a person’s own cells.


What do you love most about your job at CIRM?

Kevin: That’s hard to say, it’s like asking which is your favorite child? I love getting to work with the team here at CIRM. It’s such an incredible group of individuals who are fiercely committed to this work, but who are also ridiculously smart and funny. It makes for a great work place and one I enjoy coming into every day.

I also love working with patient advocates. Their courage, compassion and commitment to the work that we do at CIRM is inspirational. If ever I think I am having a bad day I simply have to think about what these extraordinary people go through every day and it puts my day in perspective. They are the reason we do this work. They are the reason this work has value and purpose.

Karen: You know how some people have a hard time choosing what flavor of ice cream to get? I have the same issue with science. I enjoyed my time doing stem cell experiments in the lab but at the same time, I was frustrated that my research and communications was so narrowly focused. I joined CIRM because I love educating patients and the public about all types of stem cell research. I also am a self-professed multitasker and love that my job is to find new ways to connect with different audiences through social media, blogging, and whatever I can think of!

I guess if I really had to choose a favorite, it would be managing the SPARK high school educational program. Each year, I get to work with 60 high school students who spend their summers doing stem cell research in labs across California. They are extremely motivated and it’s easy to see by watching their journeys on instagram how these students will be the next generation of talented stem cell scientists.

Todd: My interests have always zig-zagged between the worlds of science and art. I love that my job allows me to embrace both equally. I could be writing a blog about stem cell-derived mini-intestines one moment, then in the next moment I’m editing video footage from an interview with a patient.

Speaking of patients, they’re the other reason I love my job. As a graduate student I worked in a fruit fly lab so it probably doesn’t surprise you that I had virtually no interactions with patients. But as a member of the science communications team at CIRM, I’ve been fortunate to hear firsthand from the patients and their caregivers who show so much courage in the face of their disease. It makes the work we do here all the more motivating.

CIRM communications team: Todd Dubnicoff, Kevin McCormack, Maria Bonneville, Karen Ring


Please share a poem inspired by your love for stem cell research

 Kevin: I’m from Ireland so obviously I wrote a limerick.

There was a young scientist at CIRM

Whose research made some people squirm

He took lots of cells

Fed them proteins and gels

Until they were grown to full-term

 Karen: I wrote a haiku because that was the only type of poem I received a good grade for in elementary school.

Pluripotency

One stem cell to rule them all

Many paths to choose

Todd: Limerick-shimerick, Kevin. Only true poets haiku!

Shape-shifting stem cell

Hero for those who suffer

Repairing lost hope


One year ago…

New Insights into Adult Neurogenesis

To be a successful scientist, you have to expect the unexpected. No biological process or disease mechanism is ever that simple when you peel off its outer layers. Overtime, results that prove a long-believed theory can be overturned by new results that suggest an alternate theory.

UCSF scientist Arturo Alvarez-Buylla is well versed with the concept of unexpected results. His lab’s research is focused on understanding adult neurogenesis – the process of creating new nerve cells (called neurons) from neural stem cells (NSCs).

For a long time, the field of adult neurogenesis has settled on the theory that brain stem cells divide asymmetrically to create two different types of cells: neurons and neural stem cells. In this way, brain stem cells populate the brain with new neurons and they also self-renew to maintain a constant stem cell supply throughout the adult animal’s life.

New Insights into Adult Neurogenesis

Last week, Alvarez-Buylla and his colleagues published new insights on adult neurogenesis in mice in the journal Cell Stem Cell. The study overturns the original theory of asymmetrical neural stem cell division and suggests that neural stem cells divide in a symmetrical fashion that could eventually deplete their stem cell population over the lifetime of the animal.

Arturo Alvarez-Buylla explained the study’s findings in an email interview with the Stem Cellar:

Arturo Alvarez-Bulla

“Our results are not what we expected. Our work shows that postnatal NSCs are not being constantly renewed by splitting them asymmetrically, with one cell remaining as a stem cell and the other as a differentiated cell. Instead, self-renewal and differentiation are decoupled and achieved by symmetric divisions.”

In brief, the study found that neural stem cells (called B1 cells) divide symmetrically in an area of the adult mouse brain called the ventricular-subventricular zone (V-SVZ). Between 70%-80% of those symmetric divisions produced neurons while only 20%-30% created new B1 stem cells. Alvarez-Buylla said that this process would result in the gradual depletion of B1 stem cells over time and seems to be carefully choreographed for the length of the lifespan of a mouse.

What does this mean?

I asked Alvarez-Buylla how his findings in mice will impact the field and whether he expects human adult neurogenesis to follow a similar process. He explained,

“The implications are quite wide, as it changes the way we think about neural stem cell retention and aging. The cells do not seem open ended with unlimited potential to be renewed, which results in a progressive decrease in NSC number and neurogenesis with time.  Understanding the mechanisms regulating proliferation of NSCs and their self-renewal also provides new insights into how the whole process of neurogenesis is choreographed over long periods by suggesting that differentiation (generation of neurons) is regulated separately from renewal.”

He further explained that mice generate new neurons in the V-SVZ brain region throughout their lifetime while humans only appear to generate new neurons during infancy in the equivalent region of the human brain called the SVZ. In humans, he said, it remains unclear where and how many neural stem cells are retained after birth.

I also asked him how these findings will impact the development of neural stem cell-based therapies for neurological or neurodegenerative diseases. Alvarez-Buylla shared interesting insights:

“Our data also indicate that upon a self-renewing division, sibling NSCs may not be equal to each other. While one NSC might stay quiescent [non-dividing] for an extended period of time, its sister cell might become activated earlier on and either undergo another round of self-renewal or differentiate. Thus, for cell-replacement therapies it will be important to understand which kind of neuron the NSC of interest can produce, and when. The use of NSCs for brain repair requires a detailed understanding of which NSC subset will be utilized for treatment and how to induce them to produce progeny. The study also suggests that factors that control NSC renewal may be separate from those that control generation of neurons.”

Scientists developing adult NSC-based therapies will definitely need to take note of Alvarez-Buylla’s findings as some NSC populations might be more successful therapeutically than others.

Neural Stem Cells in the Wild

I’ll conclude with a beautiful image that the study’s first author, Kirsten Obernier, shared with me. It’s shows the V-SVZ of the mouse brain and a neural stem cell in red making contact with a blood vessel in green and neurons in blue.

Image of the mouse brain with a neural stem cell in red. (Credit: Kirsten Obernier, UCSF)

Kirsten described the complex morphology of B1 NSCs in the mouse brain and their dynamic behavior, which Kirsten observed by taking a time lapsed video of NSCs dividing in the mouse V-SVZ. Obernier and Alvarez-Buylla hypothesize that these NSCs could be receiving signals from their surrounding environment that tell them whether to make neurons or to self-renew.

Clearly, further research is necessary to peel back the complex layers of adult neurogenesis. If NSC differentiation is regulated separately from self-renewal, their insights could shed new light on how conditions of unregulated self-renewal like brain tumors develop.

Stem Cell Roundup: Rainbow Sherbet Fruit Fly Brains, a CRISPR/iPSC Mash-up and more

This week’s Round Up is all about the brain with some CRISPR and iPSCs sprinkled in:

Our Cool Stem Cell Image of the Week comes from Columbia University’s Zuckerman Institute:

Mann-SC-Hero-01-19-18

(Credit: Jon Enriquez/Mann Lab/Columbia’s Zuckerman Institute).

This rainbow sherbet-colored scientific art is a microscopy image of a fruit fly nervous system in which brain cells were randomly labeled with different colors. It was a figure in a Neuron study published this week showing how cells derived from the same stem cells can go down very different developmental paths but then later are “reunited” to carry out key functions, such as in this case, the nervous system control of leg movements.


A new therapeutic avenue for Parkinson’s diseaseBuck Institute

Many animal models of Parkinson’s disease are created by mutating specific genes to cause symptoms that mimic this incurable, neurodegenerative disorder. But, by far, most cases of Parkinson’s are idiopathic, a fancy term for spontaneous with no known genetic cause. So, researchers at the Buck Institute took another approach: they generated a mouse model of Parkinson’s disease using the pesticide, paraquat, exposure to which is known to increase the risk of the idiopathic form of Parkinson’s.

Their CIRM-funded study in Cell Reports showed that exposure to paraquat leads to cell senescence – in which cells shut down and stop dividing – particularly in astrocytes, brain cells that support the function of nerve cells. Ridding the mice of these astrocytes relieved some of the Parkinson’s like symptoms. What makes these results so intriguing is the team’s analysis of post-mortem brains from Parkinson’s patients also showed the hallmarks of increased senescence in astrocytes. Perhaps, therapeutic approaches that can remove senescent cells may yield novel Parkinson’s treatments.


Discovery may advance neural stem cell treatments for brain disordersSanford-Burnham Prebys Medical Discovery Institute (via Eureka Alert)

Another CIRM-funded study published this week in Nature Neuroscience may also help pave the way to new treatment strategies for neurologic disorders like Parkinson’s disease. A team at Sanford Burnham Prebys Medical Discovery Institute (SBP) discovered a novel gene regulation system that brain stem cells use to maintain their ability to self-renew.

The study centers around messenger RNA, a molecular courier that transcribes a gene’s DNA code and carries it off to be translated into a protein. The team found that the removal of a chemical tag on mRNA inside mouse brain stem cells caused them to lose their stem cell properties. Instead, too many cells specialized into mature brain cells leading to abnormal brain development in animal studies. Team lead Jing Crystal Zhao, explained how this finding is important for future therapeutic development:

CrystalZhao_headshot

Crystal Zhao

“As NSCs are increasingly explored as a cell replacement therapy for neurological disorders, understanding the basic biology of NSCs–including how they self-renew–is essential to harnessing control of their in vivo functions in the brain.”


Researchers Create First Stem Cells Using CRISPR Genome ActivationThe Gladstone Institutes

Our regular readers are most likely familiar with both CRISPR gene editing and induced pluripotent stem cell (iPSC) technologies. But, in case you missed it late last week, a Cell Stem Cell study out of Sheng Ding’s lab at the Gladstone Institutes, for the first time, combined the two by using CRISPR to make iPSCs. The study got a lot of attention including a review by Paul Knoepfler in his blog The Niche. Check it out for more details!

 

Stem cell stories that caught our eye: the tale of a tail that grows back and Zika’s devious Trojan Horse

The tale of a tail that grows back (Kevin McCormack)

Ask people what they know about geckos and the odds are they’ll tell you geckos have English accents and sell car insurance. Which tells you a lot more about the power of advertising than it does about the level of knowledge about lizards. Which is a shame, because the gecko has some amazing qualities, not the least of which is its ability to re-grow its tail. Now some researchers have discovered how it regenerates its tail, and what they’ve learned could one day help people with spinal cord injuries.

Geckos often detach a bit of their tail when being pursued by a predator, then grow a new one over the course of 30 days. Researchers at the University of Guelph in Canada found that the lizards use a combination of stem cells and proteins to do that.

They found that geckos have stem cells in their tail called radial glias. Normally these cells are dormant but that changes when the lizard loses its tail. As Matthew Vickaryous, lead author of the study, said in a news release:

“But when the tail comes off everything temporarily changes. The cells make different proteins and begin proliferating more in response to the injury. Ultimately, they make a brand new spinal cord. Once the injury is healed and the spinal cord is restored, the cells return to a resting state.”

Vickaryous hopes that understanding how the gecko can repair what is essentially an injury to its spinal cord, we’ll be better able to develop ways to help people with the same kind of injury.

The study is published in the Journal of Comparative Neurology.

Zika virus uses Trojan Horse strategy to infect developing brain
In April 2015, the World Health Organization declared that infection by Zika virus and its connection to severe birth defects was an international public health emergency. The main concern has been the virus’ link to microcephaly, a condition in which abnormal brain development causes a smaller than normal head size at birth. Microcephaly leads to number of problems in these infants including developmental delays, seizures, hearing loss and difficulty swallowing.

A false color micrograph shows microglia cells (green) infected by the Zika virus (blue). Image Muotri lab/UCSD

Since that time, researchers have been racing to better understand how Zika infection affects brain development with the hope of finding treatment strategies. Now, a CIRM-funded study in Human Molecular Genetics reports important new insights about how Zika virus may be transmitted from infected pregnant women to their unborn babies.

The UCSD researchers behind the study chose to focus on microglia cells. In a press release, team leader Alysson Muotri explained their rationale for targeting these cells:

“During embryogenesis — the early stages of prenatal development — cells called microglia form in the yolk sac and then disperse throughout the central nervous system (CNS) of the developing child. Considering the timing of [Zika] transmission, we hypothesized that microglia might be serving as a Trojan horse to transport the virus during invasion of the CNS.”

In the developing brain, microglia continually travel throughout the brain and clear away dead or infected cells. Smuggling itself aboard microglia would give Zika a devious way to slip through the body’s defenses and infect other brain cells. And that’s exactly what Dr. Muotri’s team found.

Using human induced pluripotent stem cells (iPSCs), they generated brain stem cells – the kind found in the developing brain – and in lab dish infected them with Zika virus. When iPSC-derived microglia were added to the infected neural stem cells, the microglia gobbled them up and destroyed them, just as they would do in the brain. But when those microglia were placed next to uninfected brain stem cells, the Zika virus was easily transmitted to those cells. Muotri summed up the results this way:

“Our findings show that the Zika virus can infect these early microglia, sneaking into the brain where they transmit the virus to other brain cells, resulting in the devastating neurological damage we see in some newborns.”

The team went on to show that an FDA-approved drug to treat hepatitis – a liver disease often caused by viral infection – was effective at decreasing the infection of brain stem cells by Zika-carrying microglia. Since these studies were done in petri dishes, more research will be required to confirm that the microglia are a true drug target for stopping the devastating impact of Zika on newborns.

Caught our eye: new Americans 4 Cures video, better mini-brains reveal Zika insights and iPSC recipes go head-to-head

How stem cell research gives patients hope (Karen Ring).
You can learn about the latest stem cell research for a given disease in seconds with a quick google search. You’ll find countless publications, news releases and blogs detailing the latest advancements that are bringing scientists and clinicians closer to understanding why diseases happen and how to treat or cure them.

But one thing these forms of communications lack is the personal aspect. A typical science article explains the research behind the study at the beginning and ends with a concluding statement usually saying how the research could one day lead to a treatment for X disease. It’s interesting, but not always the most inspirational way to learn about science when the formula doesn’t change.

However, I’ve started to notice that more and more, institutes and organizations are creating videos that feature the scientists/doctors that are developing these treatments AND the patients that the treatments could one day help. This is an excellent way to communicate with the public! When you watch and listen to a patient talk about their struggles with their disease and how there aren’t effective treatments at the moment, it becomes clear why funding and advancing research is important.

We have a great example of a patient-focused stem cell video to share with you today thanks to our friends at Americans for Cures, a non-profit organization that advocates for stem cell research. They posted a new video this week in honor of Stem Cell Awareness Day featuring patients and patient advocates responding to the question, “What does stem cell research give you hope for?”. Many of these patients and advocates are CIRM Stem Cell Champions that we’ve featured on our website, blog, and YouTube channel.

Americans for Cures is encouraging viewers to take their own stab at answering this important question by sharing a short message (on their website) or recording a video that they will share with the stem cell community. We hope that you are up for the challenge!

Mini-brains help uncover some of Zika’s secrets (Kevin McCormack).
One of the hardest things about trying to understand how a virus like Zika can damage the brain is that it’s hard to see what’s going on inside a living brain. That’s not surprising. It’s not considered polite to do an autopsy of someone’s brain while they are still using it.

Human organoid_800x533

Microscopic image of a mini brain organoid, showing layered neural tissue and different groups of neural stem cells (in blue, red and magenta) giving rise to neurons (green). Image: Novitch laboratory/UCLA

But now researchers at UCLA have come up with a way to mimic human brains, and that is enabling them to better understand how Zika inflicts damage on a developing fetus.

For years researchers have been using stem cells to help create “mini brain organoids”, essentially clusters of some of the cells found in the brain. They were helpful in studying some aspects of brain behavior but limited because they were very small and didn’t reflect the layered complexity of the brain.

In a study, published in the journal Cell Reports, UCLA researchers showed how they developed a new method of creating mini-brain organoids that better reflected a real brain. For example, the organoids had many of the cells found in the human cortex, the part of the brain that controls thought, speech and decision making. They also found that the different cells could communicate with each other, the way they do in a real brain.

They used these organoids to see how the Zika virus attacks the brain, damaging cells during the earliest stages of brain development.

In a news release, Momoko Watanabe, the study’s first author, says these new organoids can open up a whole new way of looking at the brain:

“While our organoids are in no way close to being fully functional human brains, they mimic the human brain structure much more consistently than other models. Other scientists can use our methods to improve brain research because the data will be more accurate and consistent from experiment to experiment and more comparable to the real human brain.”

iPSC recipes go head-to-head: which one is best?
In the ten years since the induced pluripotent stem cell (iPSC) technique was first reported, many different protocols, or recipes, for reprogramming adult cells, like skin, into iPSCs have been developed. These variations bring up the question of which reprogramming recipe is best. This question isn’t the easiest to answer given the many variables that one needs to test. Due to the cost and complexity of the methods, comparisons of iPSCs generated in different labs are often performed. But one analysis found significant lab-to-lab variability which can really muck up the ability to make a fair comparison.

A Stanford University research team, led by Dr. Joseph Wu, sought to eliminate these confounding variables so that any differences found could be attributed specifically to the recipe. So, they tested six different reprogramming methods in the same lab, using cells from the same female donor. And in turn, these cells were compared to a female source of embryonic stem cells, the gold standard of pluripotent stem cells. They reported their findings this week in Nature Biomedical Engineering.

Previous studies had hinted that the reprogramming protocol could affect the ability to fully specialize iPSCs into a particular cell type. But based on their comparisons, the protocol chosen did not have a significant impact on how well iPSCs can be matured. Differences in gene activity are a key way that researchers do side-by-side comparisons of iPSCs and embryonic stem cells. And based on the results in this study, the reprogramming method itself can influence the differences. A gene activity comparison of all the iPSCs with the embryonic stem cells found the polycomb repressive complex – a set of genes that play an important role in embryonic development and are implicated in cancer – had the biggest difference.

In a “Behind the Paper” report to the journal, first author Jared Churko, says that based on these findings, their lab now mostly uses one reprogramming protocol – which uses the Sendai virus to deliver the reprogramming genes to the cells:

“The majority of our hiPSC lines are now generated using Sendai virus. This is due to the ease in generating hiPSCs using this method as well as the little to no chance of transgene integration [a case in which a reprogramming gene inserts into the cells’ DNA which could lead to cancerous growth].”

Still, he adds a caveat that the virus does tend to linger in the cells which suggests that:

“cell source or reprogramming method utilized, each hiPSC line still requires robust characterization prior to them being used for downstream experimentation or clinical use.”

 

Blocking spike in stem cell growth after brain injury may lessen memory decline, seizures

Survivors of traumatic brain injury (TBI) often suffer from debilitating, life changing symptoms like memory decline and epileptic seizures. Researchers had observed that following TBI, a stem cell-rich area of the brain provides a spike in new nerve cell growth, presumably to help replace damaged or destroyed brain cells. But, like a lot of things in biology, more is not always better. And a new report in Stem Cell Reports provides evidence that this spark of brain cell growth shortly after TBI may actually be responsible for post-injury seizures as well as long-term memory problems for people with this condition.The Rutgers University research team behind the study came to this counterintuitive conclusion by examining brain injury in laboratory rats. They showed that brain cells at the injury site that are known to play a role in memory had doubled in number within three days after injury. But a month later, these brain cells had decreased by more than half the amount seen in rats without injury. Neural stem cells, which develop into the mature cells found in the brain, showed this same up and down pattern, suggesting they were responsible for the loss of the brain cells. Lead scientist, professor Viji Santhakumar, described how these changes in brain cell growth lead to brain injury symptoms:

“There is an initial increase in birth of new neurons after a brain injury but within weeks, there is a dramatic decrease in the normal rate at which neurons are born, depleting brain cells that under normal circumstances should be there to replace damaged cells and repair the brain’s network,” she said in a press release. “The excess new neurons lead to epileptic seizures and could contribute to cognitive decline. It is normal for the birth of new neurons to decline as we age. But what we found in our study was that after a head injury the decline seems to be more rapid.”

The researchers next aimed to slow down this increase in nerve cell growth after injury. To accomplish this goal, they used an anti-cancer drug currently in clinical trials which has been known to block the growth and survival of new nerve cells. Sure enough, the drug blocked this initial, rapid burst in nerve cells in the rats, which prevented the long-term decline in the brain cells that are involved in memory decline. The team also reported that the rats were less vulnerable to seizures when this drug was administered.

“That’s why we believe that limiting this process might be beneficial to stopping seizures after brain injury,” Dr. Santhakumar commented.

Hopefully, these findings will one day help lessen these short- and long-term, life-altering symptoms seen after brain injury.

Taming the Zika virus to kill cancer stem cells that drive lethal brain tumor

An out of control flame can be very dangerous, even life-threatening. But when harnessed, that same flame sustains life in the form of warm air, a source of light, and a means to cook.

A similar duality holds true for viruses. Once it infects the body, a virus can replicate like wildfire and cause serious illness and sometimes death. But in the lab, researchers can manipulate viruses to provide an efficient, harmless method to deliver genetic material into cells, as well as to prime the immune system to protect against future infections.

In a Journal of Experimental Medicine study published this week, researchers from the University of Washington, St. Louis and UC San Diego also show evidence that a virus, in this case the Zika virus, could even be a possible therapy for a hard-to-treat brain cancer called glioblastoma.

Brain cancer stem cells (left) are killed by Zika virus infection (image at right shows cells after Zika treatment). Image: Zhe Zhu, Washington U., St. Louis.

Recent outbreaks of the Zika virus have caused microcephaly during fetal development. Babies born with microcephaly have a much smaller than average head size due to a lack of proper brain development. Children born with this condition suffer a wide range of devastating symptoms like seizures, difficulty learning, and movement problems just to name a few. In the race to understand the outbreak, scientists have learned that the Zika virus induces microcephaly by infecting and killing brain stem cells, called neural progenitors, that are critical for the growth of the developing fetal brain.

Now, glioblastoma tumors contain a small population of cells called glioblastoma stem cells (GSCs) that, like neural progenitors, can lay dormant but also make unlimited copies of themselves.  It’s these properties of glioblastoma stem cells that are thought to allow the glioblastoma tumor to evade treatment and grow back. The research team in this study wondered if the Zika virus, which causes so much damage to neural progenitors in developing babies, could be used for good by infecting and killing cancer stem cells in glioblastoma tumors in adult patients.

To test this idea, the scientists infected glioblastoma brain tumor samples with Zika and showed that the virus spreads through the cells but primarily kills off the glioblastoma stem cells, leaving other cells in the tumor unscathed. Since radiation and chemotherapy are effective at killing most of the tumor but not the cancer stem cells, a combination of Zika and standard cancer therapies could provide a knockout punch to this aggressive brain cancer.

Even though Zika virus is much more destructive to the developing fetal brain than to adult brains, it’s hard to imagine the US Food and Drug Administration ever approving the injection of a dangerous virus into the site of a glioblastoma tumor. So, the scientists genetically modified the Zika virus to make it more sensitive to the immune system’s first line of defense called the innate immunity. With just the right balance of genetic alterations, it might be possible to retain the Zika virus’ ability to kill off cancer stem cells without causing a serious infection.

The results were encouraging though not a closed and shut case: when glioblastoma cancer stem cells were infected with these modified Zika virus strains, the virus’ cancer-killing abilities were weaker than the original Zika strains but still intact. Based on these results, co-senior author and WashU professor, Dr. Michael S. Diamond, plans to make more tweaks to the virus to harness it’s potential to treat the cancer without infecting the entire brain in the process.

“We’re going to introduce additional mutations to sensitize the virus even more to the innate immune response and prevent the infection from spreading,” said Diamond in a press release. “Once we add a few more changes, I think it’s going to be impossible for the virus to overcome them and cause disease.”

 

Brain stem cells unintentionally talk with brain tumors, allowing their spread

A stem cell’s capacity to lay quiet and, when needed, to self-renew plays a key role in restoring and maintaining the health of our organs. Unfortunately, cancer stem cells possess that same property allowing them to evade radiation and chemotherapy treatments which leads to tumor regrowth. And a CIRM-funded study published today in Cell shows the deviousness of these cancer cells goes even further. The Stanford research team behind the study found evidence that brain stem cells, which normally guide brain development and maintenance, unintentionally communicate with brain cancer cells in deadly tumors, called gliomas, providing them a means to invade other parts of the brain. But the silver lining to this scary insight is that it may lead to new treatment options for patients.

High grade gliomas do not end well
The most aggressive forms of glioma are called high grade gliomas and they carry devastating prognoses. For instance, the most common form of these tumors in children has a median survival of just 9 months with a 5-year survival of less than 1%. Surgery or anti-cancer therapies may help for a while but the tumor inevitably grows back.

MRI image of high grade glioma brain tumor (white mass on left). Image: Wikipedia

Researchers have observed that gliomas typically originate in the brain stem and very often invade a brain stem cell-rich area, called the subventrical zone (SVZ), that provides a space for the therapy-resistant cancer stem cells to hole up. This path of tumor spread is associated with a shorter time to relapse and poorer survival but the exact mechanism wasn’t known. The Stanford team hypothesized that SVZ brain stem cells release some factor that attracts the gliomas to preferentially invade that part of the brain.

To test this chemo-attraction idea, they mimicked cancer cell invasion in a specialized, dual compartment petri dish called a Boyden chamber. In the bottom compartment, they placed the liquid food, or media, that SVZ brain stem cells had been grown in. On the upper compartment, they placed the cancerous glioma cells. A porous, gelatin membrane between the two compartments acts as a barrier but allows the cells to receive signals from the lower compartment and migrate down into the media if a chemoattractant is present. And that’s what they saw: a significant glioma cell migration through the gelatin toward the brain stem cell media.

Boyden chamber assay. Image: Integr. Biol., 2009,1, 170-181

Pleiotrophin: an unintentional communicator with brain cancer cells
Something or somethings in the SVZ brain stem cell media had to be attracting the glioma cells. So, the Stanford team analyzed the composition of the media and identified four proteins that, when physically complexed together, had the same chemo-attraction ability as the media. They were pleased to find that one of the four proteins is pleiotrophin which is known to not only play a role in normal brain development and regeneration but also to increase glioma cell migration. And in this study, they showed that higher levels of pleiotrophin are present in the SVZ brain stem cell area compared to other regions of the brain. They went on to show that blocking the production of pleiotrophin in mice reduced the invasion of glioma cells into the SVZ region. This result suggests that blocking the release of pleiotrophin by brain stem cells in the SVZ could help prevent or slow down the spread of glioma in patients’ brains without the need of irradiating this important part of the brain.

The silver lining: hsp90 inhibitors have therapeutic promise

Michelle Monje, MD, PhD

To further explore this potential therapeutic approach, the team examined hsp90, one of the other three proteins complexed with pleiotrophin. Though it doesn’t have chemoattractant properties, it still is a necessary component and may act to stabilize pleiotrophin. It also turns out that inhibitors for hsp90 have already been developed in the clinic for treating various cancers. When the researchers in this study blocked hsp90 production in the SVZ region of mice, they observed a reduced invasion of glioma cells. Though clinical grade hsp90 inhibitors exist, team lead  Michelle Monje, MD, PhD – assistant professor of neurology, Stanford University – tells me that some tweaking of these drugs will be necessary to reach gliomas:

“Our challenge is to find an hsp90 inhibitor that penetrates the brain at effective concentrations.”

Once they find that inhibitor, it could provide new options, and hope, for people diagnosed with this dreadful cancer.

Stem Cell Stories that Caught our Eye: CRISPRing Human Embryos, brain stem cells slow aging & BrainStorm ALS trial joins CIRM Alpha Clinics

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

Scientists claim first CRISPR editing of human embryos in the US.

Here’s the big story this week. Scientists from Portland, Oregon claim they genetically modified human embryos using the CRISPR/Cas9 gene editing technology. While their results have yet to be published in a peer review journal (though the team say they are going to be published in a prominent journal next month), if they prove true, the study will be the first successful attempt to modify human embryos in the US.

A representation of an embryo being fertilized. Scientists can inject CRISPR during fertilization to correct genetic disorders. (Getty Images).

Steve Connor from MIT Technology Review broke the story earlier this week noting that the only reports of human embryo modification were published by Chinese scientists. The China studies revealed troubling findings. CRISPR caused “off-target” effects, a situation where the CRISPR machinery randomly introduces genetic errors in a cell’s DNA, in the embryos. It also caused mosaicism, a condition where the desired DNA sequences aren’t genetically corrected in all the cells of an embryo producing an individual with cells that have different genomes. Putting aside the ethical conundrum of modifying human embryos, these studies suggested that current gene editing technologies weren’t accurate enough to safely modify human embryos.

But a new chapter in human embryo modification is beginning. Shoukhrat Mitalipov (who is a member of CIRM’s Grants Working Group, the panel of scientific experts that reviews our funding applications) and his team from the Oregon Health and Science University said that they have developed a method to successfully modify donated human embryos that avoids the problems experienced by the Chinese scientists. The team found that introducing CRISPR at the same time an embryo was being fertilized led to successful correction of disease-causing mutations while avoiding mosaicism and “off-target” effects. They grew these embryos for a few days to confirm that the genetic modifications had worked before destroying them.

The MIT piece quoted a scientist who knows of Mitalipov’s work,

“It is proof of principle that it can work. They significantly reduced mosaicism. I don’t think it’s the start of clinical trials yet, but it does take it further than anyone has before.”

Does this discovery, if it’s true, open the door further for the creation of designer babies? For discussions about the future scientific and ethical implications of this research, I recommend reading Paul Knoepfler’s blog, this piece by Megan Molteni in Wired Magazine and Jessica Berg’s article in The Conversation.

Brain stem cells slow aging in mice

The quest for eternal youth might be one step closer thanks to a new study published this week in the journal Nature. Scientists from the Albert Einstein College of Medicine in New York discovered that stem cells found in an area of the brain called the hypothalamus can slow the aging process in mice.

The hypothalamus is located smack in the center of your brain near the brain stem. It’s responsible for essential metabolic functions such as making and secreting hormones, managing body temperature and controlling feelings of hunger and thirst. Because the body’s metabolic functions decline with age, scientists have suspected that the hypothalamus plays a role in aging.

The mouse hypothalamus. (NIH, Wikimedia).

In the current study, the team found that stem cells in the hypothalamus gradually disappear as mice age. They were curious whether the disappearance of these stem cells could jump start the aging process. When they removed these stem cells, the mice showed more advanced mental and physical signs of aging compared to untreated mice.

They also conducted the opposite experiment where they transplanted hypothalamic stem cells taken from baby mice (the idea being that these stem cells would exhibit more “youthful” qualities) into the brains of middle-aged mice and saw improvements in mental and physical functions and a 10% increase in lifespan.

So what is it about these specific stem cells that slows down aging? Do they replenish the aging brain with new healthy cells or do they secrete factors that keep the brain healthy? Interestingly, the scientists found that these stem cells secreted vesicles that contained microRNAs, which are molecules that regulate gene expression by turning genes on or off.

They injected these microRNAs into the brains of middle-aged mice and found that they reversed symptoms of aging including cognitive decline and muscle degeneration. Furthermore, when they removed hypothalamic stem cells from middle-aged mice and treated them with the microRNAs, they saw the same anti-aging effects.

In an interview with Nature News, senior author on the study, Dongsheng Cai, commented that hypothalamic stem cells could have multiple ways of regulating aging and that microRNAs are just one of their tools. For this research to translate into an anti-aging therapy, “Cai suspects that anti-ageing therapies targeting the hypothalamus would need to be administered in middle age, before a person’s muscles and metabolism have degenerated beyond a point that could be reversed.”

This study and its “Fountain of Youth” implications has received ample attention from the media. You can read more coverage from The Scientist, GenBio, and the original Albert Einstein press release.

BrainStorm ALS trial joins the CIRM Alpha Clinics

Last month, the CIRM Board approved $15.9 million in funding for BrainStorm Cell Therapeutic’s Phase 3 trial that’s testing a stem cell therapy to treat patients with a devastating neurodegenerative disease called amyotrophic lateral sclerosis or ALS (also known as Lou Gehrig’s disease).

The stem cell therapy, called NurOwn®, is made of mesenchymal stem cells extracted from a patient’s bone marrow. The stem cells are genetically modified to secrete neurotrophic factors that keep neurons in the brain healthy and prevent their destruction by diseases like ALS.

BrainStorm has tested NurOwn in early stage clinical trials in Israel and in a Phase 2 study in the US. These trials revealed that the treatment was “safe and well tolerated” and that “NurOwn also achieved multiple secondary efficacy endpoints, showing clear evidence of a clinically meaningful benefit.  Notably, response rates were higher for NurOwn-treated subjects compared to placebo at all time points in the study out to 24 weeks.”

This week, BrainStorm announced that it will launch its Phase 3 CIRM-funded trial at the UC Irvine (UCI) CIRM Alpha Stem Cell Clinic. The Alpha Clinics are a network of top medical centers in California that specialize in delivering high quality stem cell clinical trials to patients. UCI is one of four medical centers including UCLA, City of Hope, and UCSD, that make up three Alpha Clinics currently supporting 38 stem cell trials in the state.

Along with UCI, BrainStorm’s Phase 3 trial will also be conducted at two other sites in the US: Mass General Hospital in Boston and California Pacific Medical Center in San Francisco. Chaim Lebovits, President and CEO, commented,

“We are privileged to have UCI and Dr. Namita Goyal join our pivotal Phase 3 study of NurOwn. Adding UCI as an enrolling center with Dr. Goyal as Principal Investigator will make the treatment more accessible to patients in California, and we welcome the opportunity to work with this prestigious institution.”

Before the Phase 3 trial can launch at UCI, it needs to be approved by our federal regulatory agency, the Food and Drug Administration (FDA), and an Institutional Review Board (IRB), which is an independent ethics committee that reviews biomedical research on human subjects. Both these steps are required to ensure that a therapy is safe to test in patients.

With promising data from their Phase 1 and 2 trials, BrainStorm’s Phase 3 trial will likely get the green light to move forward. Dr. Goyal, who will lead the trial at the UCI Alpha Clinic, concluded:

“NurOwn is a very promising treatment with compelling Phase 2 data in patients with ALS; we look forward to further advancing it in clinical development and confirming the therapeutic benefit with Brainstorm.”

Harnessing DNA as a programmable instruction kit for stem cell function

DNA is the fundamental molecule to all living things. The genetic sequences embedded in its double-helical structure contain the instructions for producing proteins, the building blocks of our cells. When our cells divide, DNA readily unzips into two strands and makes a copy of itself for each new daughter cell. In a Nature Communications report this week, researchers at Northwestern University describe how they have harnessed DNA’s elegant design, which evolved over a billion years ago, to engineer a programmable set of on/off instructions to mimic the dynamic interactions that cells encounter in the body. This nano-sized toolkit could provide a means to better understand stem cell behavior and to develop regenerative therapies to treat a wide range of disorders.

Stupp

Instructing cells with programmable DNA-protein hybrids: switching bioactivity on and off Image: Stupp lab/Northwestern U.

While cells are what make up the tissues and organs of our bodies, it’s a bit more complicated than that. Cells also secrete proteins and molecules that form a scaffold between cells called the extracellular matrix. Though it was once thought to be merely structural, it’s clear that the matrix also plays a key role in regulating cell function. It provides a means to position multiple cell signaling molecules in just the right spot at the right time to stimulate a particular cell behavior as well as interactions between cells. This physical connection between the matrix, molecules and cells called a “niche” plays an important role for stem cell function.

Since studying cells in the laboratory involves growing them on plastic petri dishes, researchers have devised many methods for mimicking the niche to get a more accurate picture of how cells response to signals in the body. The tricky part has been to capture three main characteristics of the extracellular matrix all in one experiment; that is, the ability to add and then reverse a signal, to precisely position cell signals and to combine signals to manipulate cell function. That’s where the Northwestern team and its DNA toolkit come into the picture.

They first immobilized a single strand of DNA onto the surface of a material where cells are grown. Then they added a hybrid molecule – they call it “P-DNA” – made up of a particular signaling protein attached to a single strand of DNA that pairs with the immobilized DNA. Once those DNA strands zip together, that tethers the signaling protein to the material where the cells encounter it, effectively “switching on” that protein signal. Adding an excess of single-stranded DNA that doesn’t contain the attached protein, pushes out the P-DNA which can be washed away thereby switching off the protein signal. Then the P-DNA can be added back to restart the signal once again.

Because the DNA sequences can be easily synthesized in the lab, it allows the researchers to program many different instructions to the cells. For instance, combinations of different protein signals can be turned on simultaneously and the length of the DNA strands can precisely control the positioning of cell-protein interactions. The researchers used this system to show that spinal cord neural stem cells, which naturally clump together in neurospheres when grown in a dish, can be instructed to spread out on the dish’s surface and begin specializing into mature brain cells. But when that signal is turned off, the cells ball up together again into the neurospheres.

Team lead Samuel Stupp looks to this reversible, on-demand control of cell activity as means to develop patient specific therapies in the future:

stupp-samuel

Samuel Stupp

“People would love to have cell therapies that utilize stem cells derived from their own bodies to regenerate tissue. In principle, this will eventually be possible, but one needs procedures that are effective at expanding and differentiating cells in order to do so. Our technology does that,” he said in a university press release.