Stem cell stories that caught our eye: turning on T cells; fixing our brains; progress and trends in stem cells; and one young man’s journey to recover from a devastating injury


A healthy T cell

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

Directing the creation of T cells. To paraphrase the GOP Presidential nominee, any sane person LOVES, LOVES LOVES their T cells, in a HUGE way, so HUGE. They scamper around the body getting rid of viruses and the tiny cancers we all have in us all the time. A CIRM-funded team at CalTech has worked out the steps our genetic machinery must take to make more of them, a first step in letting physicians turn up the action of our immune systems.

We have known for some time the identity of the genetic switch that is the last, critical step in turning blood stem cells into T cells, but nothing in our body is as simple as a single on-off event. The Caltech team isolated four genetic factors in the path leading to that main switch and, somewhat unsuspected, they found out those four steps had to be activated sequentially, not all at the same time. They discovered the path by engineering mouse cells so that the main T cell switch, Bcl11b, glows under a microscope when it is turned on.

“We identify the contributions of four regulators of Bcl11b, which are all needed for its activation but carry out surprisingly different functions in enabling the gene to be turned on,” said Ellen Rothenberg, the senior author in a university press release picked up by Innovations Report. “It’s interesting–the gene still needs the full quorum of transcription factors, but we now find that it also needs them to work in the right order.”

Video primer on stem cells in the brain.  In conjunction with an article in its August issue, Scientific American posted a video from the Brain Forum in Switzerland of Elena Cattaneo of the University of Milan explaining the basics of adult versus pluripotent stem cells, and in particular how we are thinking about using them to repair diseases in the brain.

The 20-minute talk gives a brief review of pioneers who “stood alone in unmarked territory.” She asks how can stem cells be so powerful; and answers by saying they have lots of secrets and those secrets are what stem cell scientist like her are working to unravel.  She notes stem cells have never seen a brain, but if you show them a few factors they can become specialized nerves. After discussing collaborations in Europe to grow replacement dopamine neurons for Parkinson’s disease, she went on to describe her own effort to do the same thing in Huntington’s disease, but in this case create the striatal nerves lost in that disease.

The video closes with a discussion of how basic stem cell research can answer evolutionary questions, in particular how genetic changes allowed higher organisms to develop more complex nervous systems.

kelley and kent

CIRM Science Officers Kelly Shepard and Kent Fitzgerald

A stem cell review that hits close to home.  IEEE Pulse, a publication for scientists who mix engineering and medicine and biology, had one of their reporters interview two of our colleagues on CIRM’s science team. They asked senior science officers Kelly Shepard and Kent Fitzgerald to reflect on how the stem cell field has progressed based on their experience working to attract top researchers to apply for our grants and watching our panel of outside reviewers select the top 20 to 30 percent of each set of applicants.

One of the biggest changes has been a move from animal stem cell models to work with human stem cells, and because of CIRM’s dedicated and sustained funding through the voter initiative Proposition 71, California scientists have led the way in this change. Kelly described examples of how mouse and human systems are different and having data on human cells has been critical to moving toward therapies.

Kelly and Kent address several technology trends. They note how quickly stem cell scientists have wrapped their arms around the new trendy gene editing technology CRISPR and discuss ways it is being used in the field. They also discuss the important role of our recently developed ability to perform single cell analysis and other technologies like using vessels called exosomes that carry some of the same factors as stem cells without having to go through all the issues around transplanting whole cells.

“We’re really looking to move things from discovery to the clinic. CIRM has laid the foundation by establishing a good understanding of mechanistic biology and how stem cells work and is now taking the knowledge and applying it for the benefit of patients,” Kent said toward the end of the interview.

jake and family

Jake Javier and his family

Jake’s story: one young man’s journey to and through a stem cell transplant; As a former TV writer and producer I tend to be quite critical about the way TV news typically covers medical stories. But a recent story on KTVU, the Fox News affiliate here in the San Francisco Bay Area, showed how these stories can be done in a way that balances hope, and accuracy.

Reporter Julie Haener followed the story of Jake Javier – we have blogged about Jake before – a young man who broke his spine and was then given a stem cell transplant as part of the Asterias Biotherapeutics clinical trial that CIRM is funding.

It’s a touching story that highlights the difficulty treating these injuries, but also the hope that stem cell therapies holds out for people like Jake, and of course for his family too.

If you want to see how a TV story can be done well, this is a great example.

Stem cell stories that caught our eye: a surprising benefit of fasting, faster way to make iPSCs, unlocking the secret of leukemia cancer cells

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


Is fasting the fountain of youth?

Among the many insults our bodies endure in old age is a weakened immune system which leaves the elderly more susceptible to infection. Chemotherapy patients also face the same predicament due to the immune suppressing effects of their toxic anticancer treatments. While many researchers aim to develop drugs or cell therapies to protect the immune system, a University of Southern California research report this week suggests an effective alternative intervention that’s startlingly straightforward: fasting for 72 hours.

The study published in Cell Stem Cell showed that cycles of prolonged fasting in older mice led to a decrease in white blood cells which in turn set off a regenerative burst of blood stem cells. This restart of the blood stem cells replenished the immune system with new white blood cells. In a pilot Phase 1 clinical trial, cancer patients who fasted 72 hours before receiving chemotherapy maintained normal levels of white blood cells.

A look at the molecular level of the process pointed to a decrease in the levels of a protein called PKA in stem cells during the fasting period. In a university press release carried by Science Daily, the study leader, Valter Longo, explained the significance of this finding:

“PKA is the key gene that needs to shut down in order for these stem cells to switch into regenerative mode. It gives the ‘okay’ for stem cells to go ahead and begin proliferating and rebuild the entire system. And the good news is that the body got rid of the parts of the system that might be damaged or old, the inefficient parts, during the fasting. Now, if you start with a system heavily damaged by chemotherapy or aging, fasting cycles can generate, literally, a new immune system.”

In additional to necessary follow up studies, the team is looking into whether fasting could benefit other organ systems besides the immune system. If the data holds up, it could be that regular fasting or direct targeting of PKA could put us on the road to a much more graceful and healthier aging process.


Faster, cheaper, safer way to use iPS cells

Science, like traffic in any major city, never moves quite as quickly as you would like, but now Japanese researchers are teaming up to develop a faster, and cheaper way of using iPSC’s , pluripotent stem cells that are reprogrammed from adult cells, for transplants.

Part of the beauty of iPSCs is that because those cells came from the patient themselves, there is less risk of rejection. But there are problems with this method. Taking adult cells and turning them into enough cells to treat someone can take a long time. It’s expensive too.

But now researchers at Kyoto University and three other institutions in Japan have announced they are teaming up to change that. They want to create a stockpile of iPSCs that are resistant to immunological rejection, and are ready to be shipped out to researchers.

Having a stockpile of ready-to-use iPSCs on hand means researchers won’t have to wait months to develop their own, so they can speed up their work.

Shinya Yamanaka, who developed the technique to create iPSCs and won the Nobel prize for his efforts, say there’s another advantage with this collaboration. In a news article on Nikkei’s Asian Review he said these cells will have been screened to make sure they don’t carry any potentially cancer-causing mutations.

“We will take all possible measures to look into the safety in each case, and we’ll give the green light once we’ve determined they are sound scientifically. If there is any concern at all, we will put a stop to it.”

CIRM is already working towards a similar goal with our iPSC Initiative.

Unlocking the secrets of leukemia stem cells


Zombies: courtesy “The Walking Dead”

Any article that has an opening sentence that says “Cancer stem cells are like zombies” has to be worth reading. And a report in ScienceMag  that explains how pre-leukemia white blood cell precursors become leukemia cancer stem cells is definitely worth reading.

The article is about a study in the journal Cell Stem Cell by researchers at UC San Diego. The senior author is Catriona Jamieson:

“In this study, we showed that cancer stem cells co-opt an RNA editing system to clone themselves. What’s more, we found a method to dial it down.”

An enzyme called ADAR1 is known to spur cancer growth by manipulating small pieces of genetic material known as microRNA. Jamieson and her team wanted to track how that was done. They discovered it is a cascade of events, and that once the first step is taken a series of others quickly followed on.

They found that when white blood cells have a genetic mutation that is linked to leukemia, they are prone to inflammation. That inflammation then activates ADAR1, which in turn slows down a segment of microRNA called let-7 resulting in increased cell growth. The end result is that the white blood cells that began this cascade become leukemia stem cells and spread an aggressive and frequently treatment-resistant form of the blood cancer.

Having uncovered how ADAR1 works Jamieson and her team then tried to find a way to stop it. They discovered that by blocking the white blood cells susceptibility to inflammation, they could prevent the cascade from even starting. They also found that by using a compound called 8-Aza they could impede ADAR1’s ability to stimulate cell growth by around 40 percent.


Catriona Jamieson – definitely not a zombie

Jamieson says the findings open up all sorts of possibilities:

“Based on this research, we believe that detecting ADAR1 activity will be important for predicting cancer progression. In addition, inhibiting this enzyme represents a unique therapeutic vulnerability in cancer stem cells with active inflammatory signaling that may respond to pharmacologic inhibitors of inflammation sensitivity or selective ADAR1 inhibitors that are currently being developed.”

This wasn’t a CIRM-funded study but we have supported other projects by Dr. Jamieson that have led to clinical trials.





UCSF study explains how chronic inflammation impairs blood stem cell function

Human blood (red) and immune cells (green) are made from hematopoietic/blood stem cells. Photo credit: ZEISS Microscopy.

Human blood (red) and immune cells (green) are made from hematopoietic/blood stem cells. Photo credit: ZEISS Microscopy.

Inflammation is the immune system’s natural protective response to infection and injury. It involves the activation and mobilization of immune cells that can kill off foreign invaders and help repair damaged tissue. At the heart of the inflammatory response are hematopoietic stem cells (HSCs). These are blood stem cells found in the bone marrow that give rise to all blood cell types.

Under normal conditions, HSCs lie in a dormant state. But in response to inflammation they are triggered to rapidly divide and to differentiate into the immune cells needed. This initial response is beneficial in fighting off infection, however if left on for too long, HSCs lose their ability to self-renew (or make more of themselves) and regenerate a healthy blood system.

IL-1: Good Cop or Bad Cop?

A key player in the immune response to inflammation is a cytokine protein called Interleukin-1 or IL-1. It plays a beneficial role during an initial or acute inflammatory response: IL-1 along with other pro-inflammatory cytokines signals to HSCs that inflammation or infection is occurring and recruits certain immune cells from the blood into the tissue where they are needed.

However, IL-1 can also have negative effects on the immune system and high levels of this cytokine are found in patients with chronic inflammatory diseases such as obesity, diabetes and atherosclerosis. When HSCs are exposed IL-1 for long periods of time, they lose their regenerative abilities and  overproduce specific types of aggressive immune cells called myeloid cells that are needed to fight infection and repair injury but can also cause chronic inflammation and tissue damage. This can create an imbalance of blood cell types that impairs the function of the immune system.

So is IL-1 the good cop or the bad cop when it comes to inflammation and disease? A new CIRM-funded study from the University of California San Francisco (UCSF), published yesterday in Nature Cell Biology, might have the answer.

A double-edged sword

The study was led by first author Dr. Eric Pietras, who is now an Assistant Professor of Hematology at the University of Colorado Anschutz Medical Campus. He along with senior author and UCSF Professor Dr. Emmanuelle Passegue, were interested in understanding whether IL-1 was a bystander or an active player in causing this transformation in HSCs that leads to chronic inflammatory disease.

To answer this question, Pietras and Passegue exposed mouse HSCs to IL-1, both in a cell culture dish and in mice. They found that IL-1 drove HSCs to rapidly differentiate into myeloid cells by activating a molecular circuit directed by the PU.1 gene, which is important for regulating HSC blood production. However, when mice were exposed to IL-1 for an extended period of 70 days – to mimic chronic inflammation – their HSCs were no longer able to do their normal job of regenerating all the cells of the blood and immune system.

I reached out to Dr. Pietras and asked him to explain what new insights his study has produced about the role of IL-1 during inflammation.

Eric Pietras

Eric Pietras

“IL-1 really is a double-edged sword; it’s great for turning on HSCs when you need them to make new first-responder myeloid cells quickly due to an injury or infection, and on the other hand, failure to turn the signal back off severely disrupts the ability of HSCs to make a balanced, healthy blood system, particularly in a regenerative context. I think this provides us with a clearer picture of why the blood system often functions poorly in chronic inflammatory disease patients.”


Negative effects of IL-1 are reversible

There’s good news though. Pietras and his team were able to reverse the negative effects of chronic IL-1 exposure on HSCs by simply removing IL-1. They proved this by transplanting HSCs from mice that were chronically treated with IL-1 and then taken off the treatment for a few weeks into irradiated mice that had no bone marrow and therefore no immune system. The transplanted HSCs were able to repopulate the entire immune system of the irradiated mice and did not show any regenerative dysfunction due to previous IL-1 treatment.

Dr. Pietras commented on the importance of their study:

“An important dimension of our study is to show in principle that HSCs can recover their functionality and return to making a healthy and balanced blood system if you can give them a break from the constant presence of inflammatory signals. This tells us that the negative effects of chronic inflammation on HSCs can be largely reversed if you can provide them with a break from the constant ‘emergency’ state IL-1 makes them think they’re in. This could impact how we treat chronic inflammatory disease.


Blocking IL-1 to treat chronic inflammation

So will drugs that inhibit IL-1 be a future therapy for patients suffering from chronic inflammatory disease? Anti-IL-1 drugs have been around for a while – one example is Kineret, which is an FDA-approved treatment for rheumatoid arthritis. But there are many other diseases caused by chronic inflammation that may or may not benefit from such treatment.

Dr. Passegue, in a UCSF press release, explained that their study’s findings are important for determining how anti-IL-1 therapy could be beneficial for patients.

“Understanding this mechanism helps us understand why these drugs are such promising treatments for patients with chronic inflammation.”

She also hinted that IL-1 could be a double-edged sword in stem cell populations of other tissues and that “reducing chronic IL-1 exposure may be an important approach for improving stem cell health and tissue function in the context of both inflammatory disease and normal aging.”

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Scientists tackle aging by stabilizing defective blood stem cells in mice

Aging is an inevitable process that effects every cell, tissue, and organ in your body. You can live longer by maintaining a healthy, active lifestyle, but there is no magic pill that can prevent your body’s natural processes from slowly breaking down and becoming less efficient. As author Chinua Achebe would say, “Things Fall Apart”.

Adult stem cells are an unfortunate victim of the aging process. They have the important job of replenishing the cells in your body throughout your lifetime. However, as you grow older, adult stem cells lose their regenerative ability and fail to maintain the integrity and function of their tissues and organs. This can happen for a number of reasons, but no matter the cause, dysfunctional stem cells can accelerate aging and contribute to a shortened lifespan.

So to put it simply, aging adult stem cells = decline in stem cell function = shortened lifespan.

Dysfunctional blood stem cells make an unhappy immune system

Human blood (red) and immune cells (green) are made from hematopoietic/blood stem cells. Photo credit: ZEISS Microscopy.

Human blood (red) and immune cells (green) are made from hematopoietic/blood stem cells. Photo credit: ZEISS Microscopy.

A good example of this process is hematopoietic stem cells (HSCs), which are adult stem cells found in bone marrow that make all the cells in our blood and immune system. When HSCs get old, they lose their edge and fail to generate some of the important blood cell types that are crucial for a healthy immune system. This can be life-threatening for elderly people who are at higher risk for infections and disease.

So how can we improve the function of aging HSCs to boost the immune system in older people and potentially extend their healthy years of life? A team of researchers from Germany might have an answer. They’ve identified a genetic switch that revitalizes aged, defective HSCs in mice and prolongs their lifespan. They published their findings this week in Nature Cell Biology.

Identifying the Per-petrator for aging HSCs

The perpetrator in this story is a gene called Per2. The team identified Per2 through a genetic screen of hundreds of potential tumor suppressor genes that could potentially impair the regenerative abilities of HSCs in response to DNA damage caused by aging.

It turns out that the Per2 gene is turned on in a subset of HSCs, called lymphoid-HSCs, that preferentially generate blood cells in the lymphatic system. These include B and T cells, both important parts of our immune system. When Per2 is turned on in lymphoid-HSCs, it activates the DNA damage response pathway. While responding to DNA damage may sound like a good thing, it also slows down the cell division process and prevents lymphoid-HSCs from producing their normal amount of lymphoid cells. Adding insult to injury, Per2 also activates the p53-dependent apoptosis pathway, which causes programmed cell death and further reduces the number of HSCs in reserve.

To address these problems, the team decided to delete the Per2 gene in mice and study the function of their HSCs as they aged. They found that removing Per2 stabilized lymphoid-HSCs and rescued their ability to generate the appropriate number of lymphoid cells. Per2 deletion also boosted their immune system, making the mice less susceptible to infection, and extended their lifespan by as much as 15 percent.

A key finding was that deleting Per2 did not increase the incidence of tumors in the aging mice – a logical concern as Per2 mutations in humans are link to increased cancer risk.

Per2 might not be a Per-fect solution for healthy aging

In summary, getting rid of Per2 in the HSCs of older mice improves their function and the function of their immune system while also extending their lifespan.

Senior author on the study, Karl Lenhard Rudolph, commented about their findings in a news release:

Karl Lenhard Rudolph. Photo: Anne Günther/FSU

Karl Lenhard Rudolph.

“All in all, these results are very promising, but equally surprising. We did not expect such a strong connection between switching off a single gene and improving the immune system so clearly.”



So Per2 may be a good healthy aging target in mice, but the real question is whether these results will translate to humans. Per2 is a circadian rhythm gene and is important for regulating the sleep-wake cycle. Deleting this gene in humans could cause sleep disorders and other unwanted side effects.

Rudolph acknowledges that his team needs to move their focus from mouse to humans.

“It is not yet clear whether this mutation in humans would have a benefit such as improved immune functions in aging — it is of great interest for us to further investigate this question.”

UCLA Scientists Find 3000 New Genes in “Junk DNA” of Immune Stem Cells

Genes and Junk

Do you remember learning about Junk DNA when you took Biology in high school? The term was used to described 98% of the human genome that doesn’t make up its approximately 22,000 genes. We used to think that Junk DNA didn’t serve a purpose, but that was before we discovered special elements called non-coding RNAs that call Junk DNA their home. But we’re getting ahead of ourselves, so let’s take a step back.

Genes are sequences of DNA that contain the blueprints for the proteins that make your cells and organs function. Before a gene can become a protein, its transformed into a molecule called an RNA. RNAs contain messages that tell a cell’s machinery what types of protein to make and how many.

Not Junk After All

Now back to “Junk DNA”… scientists thought that because this mass of DNA sequences was never turned into protein, it served no purpose. It turns out that they couldn’t be farther from the facts.

There are actually sequences of DNA in our genomes that are blueprints for RNAs that never become proteins. Scientists call them “non-coding” RNAs, and they play very important roles in the body such as replicating DNA and regulating gene expression – deciding which genes are turned on and which are turned off.

Another important function that non-coding RNAs control is cell differentiation, or the maturation of immature cells into adult cells. Differentiation is a complicated process, and because non-coding RNAs are relatively new to the scientific world, we haven’t figured out their exact roles in the differentiation of stem cells into adult cells.

Understanding Immune Cell Development

In a study published this week in Nature Immunology, UCLA scientists reported the discovery of 3000 new genes that make a type of non-coding RNA called a long non-coding RNA (lncRNA) that regulates the differentiation of stem cells into mature immune cells like B and T cells, which play a key role in fighting infection. This important study was funded in part by CIRM.

UCLA scientists David Casero and Gay Crooks with the sequencing machine that separated the genetic information within the bone marrow and thymus gland tissue stem cells. (Image credit: Mirabai Vogt-James, UCLA Broad Stem Cell Research Center)

UCLA scientists David Casero and Gay Crooks with the sequencing machine used to identify the 3000 new genes. (Image credit: Mirabai Vogt-James, UCLA Broad Stem Cell Research Center)

Using sequencing technology and bioinformatics, they mapped the RNA landscape (known as the transcriptome) of rare stem cells isolated from human bone marrow (hematopoietic stem cells) and the thymus (lymphoid progenitor cells). They identified over 9000 genes that produced lncRNAs that were important for moderating various stages of immune cell development. Of this number, over 3000 were genes whose lncRNAs hadn’t been found before.

First author, David Casero explained the importance of their discovery in a UCLA press release:

Our findings are exciting because they provide a huge and unique resource for the whole immunology community. We will now be able to drill down on the specific LncRNA genes that seem to be most important at each stage of immune cell development and understand how they function individually and together to control the process.


Co-senior author and UCLA professor Gay Crooks explained that the goal of their work was to gain a better understanding of how the immune system develops in order to battle serious diseases that affect it and open up avenues for generating better cell therapies.

If we can understand how the immune system is generated and maintained during life, we can find ways to improve production of immune cells for potential therapies after chemotherapy, radiation and bone marrow transplant, or for patients with HIV and inherited immune deficiencies. In addition, by understanding the genes that control this process we can better understand how they are changed in cancers like leukemia and lymphoma.


Final Words

While this study focused on the role of lncRNAs in the development of the immune system and the differentiation of immune stem cells, the technology in this study can be used to understand the development of other systems and organs.

Scientists are already publishing papers on the role of lncRNAs in the differentiation of stem cells in the brain and heart, and further work in this field will undoubtedly uncover many new and important lncRNA genes. If the pace keeps up, the term “Junk DNA” will need to be retired to the junk yard.


Image source

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Helping patient’s fight back against deadliest form of skin cancer

Caladrius Biosciences has been funded by CIRM to conduct a Phase 3 clinical trial to treat the most severe form of skin cancer: metastatic melanoma. Metastatic melanoma is a disease with no effective treatment, only around 15 percent of people with it survive five years, and every year it claims an estimated 10,000 lives in the U.S.

The CIRM/Caladrius Clinical Advisory Panel meets to chart future of clinical trial

The CIRM/Caladrius Clinical Advisory Panel meets to chart future of clinical trial

The Caladrius team has developed an innovative cancer treatment that is designed to target the cells responsible for tumor growth and spread. These are called cancer stem cells or tumor-initiating cells. Cancer stem cells can spread in the body because they have the ability to evade the body’s immune defense and survive standard anti-cancer treatments such as chemotherapy. The aim of the Caladrius treatment is to train the body’s immune system to recognize the cancer stem cells and attack them.

Attacking the cancer

The treatment process involves taking a sample of a patient’s own tumor and, in a laboratory, isolating specific cells responsible for tumor growth . Cells from the patient’s blood, called “peripheral blood monocytes,” are also collected. The mononucleocytes are responsible for helping the body’s immune system fight disease. The tumor and blood cells (after maturation into dendritic cells) are then combined and incubated so that the patient’s immune cells become trained to recognize the cancer cells.

After the incubation period, the patient’s immune cells are injected back into their body where they generate an immune response to the cancer cells. The treatment is like a vaccine because it trains the body’s immune system to recognize and rapidly attack the source of disease.

Recruiting the patients

Caladrius has already dosed the first patient in the trial (which is double blinded so no one knows if the patient got the therapy or a placebo) and hopes to recruit 250 patients altogether.

This is the first Phase 3 trial that CIRM has funded so we’re obviously excited about its potential to help people battling this deadly disease.  In a recent news release David J. Mazzo, the CEO of Caladrius echoed this excitement, with a sense of cautious optimism:

“The dosing of the first patient in this Phase 3 trial is an important milestone for our Company and the timing underscores our focus on this program and our commitment to impeccable trial execution. We are delighted by the enthusiasm and productivity of the team at Jefferson University (where the patient was dosed) and other trial sites around the country and look forward to translating that into optimized patient enrollment and a rapid completion of the Phase 3 trial.”

And that’s the key now. They have the science. They have the funding. Now they need the patients. That’s why we are all working together to help Caladrius recruit patients as quickly as possible. Because their work perfectly reflects our mission of accelerating the development of stem cell therapies for patients with unmet medical needs.

You can learn more about what the study involves and who is eligible by clicking here.

Breast Cancer Tumors Recruit Immune Cells to the Dark Side

We rely on our immune system to stave off all classes of disease—but what happens when the very system responsible for keeping us healthy turns to the dark side? In new research published today, scientists uncover new evidence that reveals how breast cancer tumors can actually recruit immune cells to spur the spread of disease.

Some forms of breast cancer tumors can actually turn the body's own immune system against itself.

Some forms of breast cancer tumors can actually turn the body’s own immune system against itself.

Breast cancer is one of the most common cancers, and if caught early, is highly treatable. In fact, the majority of deaths from breast cancer occur because the disease has been caught too late, having already spread to other parts of the body, a process called ‘metastasis.’ Recently, scientists discovered that women who have a heightened number of a particular type of immune cells, called ‘neutrophils,’ in their blood stream have a higher chance of their breast cancer metastasizing to other tissues. But they couldn’t figure out why.

Enter Karin de Visser, and her team at the Netherlands Cancer Institute, who announce today in the journal Nature the precise link between neutrophil immune cells and breast cancer metastasis.

They found that some types of breast tumors are particularly nefarious, sending out signals to the person’s immune system to speed up their production of neutrophils. And then they instruct these newly activated neutrophils to go rogue.

Rather than attack the tumor, these neutrophils turn on the immune system. They especially focus their efforts at blocking T cells—the type of immune cells whose job is normally to target and attack cancer cells. Further examination in mouse models of breast cancer revealed a particular protein, called interleukin 17 (or IL17) played a key role in this process. As Visser explained in today’s news release:

“We saw in our experiments that IL17 is crucial for the increased production of neutrophils. And not only that, it turns out that this is also the molecule that changes the behavior of the neutrophils, causing them to become T cell inhibitory.”

The solution then, was clear: block the connection, or pathway, between IL17 and neutrophils, and you can thwart the tumor’s efforts. And when Visser and her team, including first author and postdoctoral researcher Seth Coffelt, did this they saw a significant improvement. When the IL17-neutrophil pathway was blocked in the mouse models, the tumors failed to spread at the same rate.

“What’s notable is that blocking the IL17-neutrophil route prevented the development of metastases, but did not affect the primary tumor,” Visser added. “So this could be a promising strategy to prevent the tumor from spreading.”

The researchers are cautious about focusing their efforts on blocking neutrophils, however, as these cells are in and of themselves important to stave off infections. A breast cancer patient with neutrophil levels that were too low would be at risk for developing a whole host of infections from dangerous pathogens. As such, the research team argues that focusing on ways to block IL17 is the best option.

Just last month, the FDA approved an anti-IL17 based therapy to treat psoriasis. This therapy, or others like it, could be harnessed to treat aggressive breast cancers. Says Visser:

“It would be very interesting to investigate whether these already existing drugs are beneficial for breast cancer patients. It may be possible to turn these traitors of the immune system back towards the good side and prevent their ability to promote breast cancer metastasis.”

Goodnight, Stem Cells: How Well Rested Cells Keep Us Healthy

Plenty of studies show that a lack of sleep is nothing but bad news and can contribute to a whole host of health problems like heart disease, poor memory, high blood pressure and obesity.


Even stem cells need rest to stay healthy

In a sense, the same holds true for the stem cells in our body. In response to injury, adult stem cells go to work by dividing and specializing into the cells needed to heal specific tissues and organs. But they also need to rest for long-lasting health. Each cell division carries a risk of introducing DNA mutations—and with it, a risk for cancer. Too much cell division can also deplete the stem cell supply, crippling the healing process. So it’s just as important for the stem cells to assume an inactive, or quiescent, state to maintain their ability to mend the body. Blood stem cells for instance are mostly quiescent and only divide about every two months to renew their reserves.

Even though the importance of this balance is well documented, exactly how it’s achieved is not well understood; that is, until now. Earlier this week, a CIRM-funded research team from The Scripps Research Institute (TSRI) reported on the identification of an enzyme that’s key in controlling the work-rest balance in blood stem cells, also called hematopoietic stem cells (HSCs). Their study, published in the journal Blood, could point the way to drugs that treat anemias, blood cancers, and other blood disorders.

Previous studies in other cell types suggested that this key enzyme, called ItpkB, might play a role in promoting a rested state in HSCs. Senior author Karsten Sauer explained their reasoning for focusing on the enzyme in a press release:

“What made ItpkB an attractive protein to study is that it can dampen activating signaling in other cells. We hypothesized that ItpkB might do the same in HSCs to keep them at rest. Moreover, ItpkB is an enzyme whose function can be controlled by small molecules. This might facilitate drug development if our hypothesis were true.”

Senior author Karsten Sauer is an associate professor at The Scripps Research Institute.

Senior author Karsten Sauer is an associate professor at The Scripps Research Institute.

To test their hypothesis, the team studied HSCs in mice that completely lacked ItpkB. Sure enough, without ItpkB the HSCs got stuck in the “on” position and continually multiplied until the supply of HSCs stores in the bone marrow were exhausted. Without these stem cells, the mice could no longer produce red blood cells, which deliver oxygen to the body or white blood cells, which fight off infection. As a result the animals died due to severe anemia and bone marrow failure. Sauer used a great analogy to describe the result:

“It’s like a car—you need to hit the gas pedal to get some activity, but if you hit it too hard, you can crash into a wall. ItpkB is that spring that prevents you from pushing the pedal all the way through.”

With this new understanding of how balancing stem cell activation and deactivation works, Sauer and his team have their sights set on human therapies:

“If we can show that ItpkB also keeps human HSCs healthy, this could open avenues to target ItpkB to improve HSC function in bone marrow failure syndromes and immunodeficiencies or to increase the success rates of HSC transplantation therapies for leukemias and lymphomas.”

Stem Cell Stories that Caught our Eye: Skin Cells to Brain Cells in One Fell Swoop, #WeAreResearch Goes Viral, and Genes Helps Stem Cells Fight Disease

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

Building a Better Brain Cell. Thanks to advances in stem cell biology, scientists have found ways to turn adult cells, such as skin cells, back into cells that closely resemble embryonic stem cells. They can then coax them into becoming virtually any cell in the body.

But scientists have more recently begun to devise ways to change cells from one type into another without first having to go back to a stem cell-like state. And now, a team from Washington University in St. Louis has done exactly that.

As reported this week in New Scientist, researcher Andrew Yoo and his team used microRNAs—a type of ‘signaling molecule’—to reprogram adult human skin cells into medium spiny neurons(MSNs), the type of brain cell involved in the deadly neurodegenerative condition, Huntington’s disease.

“Within four weeks the skin cells had changed into MSNs. When put into the brains of mice, the cells survived for at least six months and made connections with the native tissue,” explained New Scientist’s Clare Wilson.

This process, called ‘transdifferentiation,’ has the potential to serve as a faster, potentially safer alternative to creating stem cells.

#WeAreResearch Puts a Face on Science. The latest research breakthroughs often focus on the science itself, and deservedly so. But exactly who performed that research, the close-knit team who spent many hours at the lab bench and together worked to solve a key scientific problem, can sometimes get lost in the shuffle.

#WeAreResearch submission from The Thomson Lab at the University of California, San Francisco. This lab uses optogenetics, and RNAseq to probe cell fate decisions.

#WeAreResearch submission from The Thomson Lab at the University of California, San Francisco. This lab uses optogenetics, and RNAseq to probe cell fate decisions.

Enter #WeAreResearch, a new campaign led by the American Society for Cell Biology (ASCB) that seeks to show off science’s more ‘human side.’

Many California-based stem cell teams have participated—including CIRM grantee Larry Goldstein and his lab!

Check out the entire collection of submissions and, if you’re a member of a lab, submit your own. Prizes await the best submissions—so now’s your chance to get creative.

New Genes Help Stem Cells Fight Infection. Finally, UCLA scientists have discovered how stem cells ‘team up’ with a newly discovered set of genes in order to stave off infection.

Reporting in the latest issue of the journal Current Biology, and summarized in a UCLA news release, Julian Martinez-Agosto and his team describe how two genes—adorably named Yorkie and Scalloped—set in motion a series of events, a molecular Rube Goldberg device, that transforms stem cells into a type of immune system cell.

Importantly, the team found that without these genes, the wrong kind of cell gets made—meaning that these genes play a central role in the body’s healthy immune response.

Mapping out the complex signaling patterns that exist between genes and cells is crucial as researchers try and find ways to, in this case, improve the body’s immune response by manipulating them.

Harder, Better, Faster, Stronger: Scientists Work to Create Improved Immune System One Cell at a Time

The human immune system is the body’s best defense against invaders. But even our hardy immune systems can sometimes be outpaced by particularly dangerous bacteria, viruses or other pathogens, or even by cancer.

Salk Institute scientists have developed a new cellular reprogramming technique that could one day boost a weakened immune system.

Salk Institute scientists have developed a new cellular reprogramming technique that could one day boost a weakened immune system.

But what if we could give our immune system a boost when it needs it most? Last week scientists at the Salk Institute for Biological Sciences devised a new method of doing just that.

Reporting in the latest issue of the journal Stem Cells, Dr. Juan Carlos Izpisua Belmonte and his team announce a new method of creating—and then transplanting—white blood cells into laboratory mice. This new and improved method could have significant ramifications for how doctors attack the most relentless disease.

The authors achieved this transformation through the reprogramming of skin cells into white blood cells. This process builds on induced pluripotent stem cell, or iPS cell, technology, in which the introduction of a set of genes can effectively turn one cell type into another.

This Nobel prize-winning approach, while revolutionary, is still a many months’ long process. In this study, the Salk team found a way to shorten the cellular ‘reprogramming’ process from several months to just a few weeks.

“The process is quick and safe in mice,” said Izpisua Belmonte in a news release. “It circumvents long-standing obstacles that have plagued the reprogramming of human cells for therapeutic and regenerative purposes.”

Traditional reprogramming methods change one cell type, such as a skin cell, into a different cell type by first taking them back into a stem cell-like, or ‘pluripotent’ state. But here, the research team didn’t take the cells all the way back to pluripotency. Instead, they simply wiped the cell’s memory—and gave it a new one. As first author Dr. Ignacio Sancho-Martinez explained:

“We tell skin cells to forget what they are and become what we tell them to be—in this case, white blood cells. Only two biological molecules are needed to induce such cellular memory loss and to direct a new cell fate.”

This technique, which they dubbed ‘indirect lineage conversion,’ uses the molecule SOX2 to wipe the skin cell’s memory. They then use another molecule called miRNA 125b to reprogram the cell into a white blood cell.

These newly generated cells appear to engraft far better than cells derived from traditional iPS cell technology, opening the door to therapies that more effectively introduce these immune cells into the human body. As Sanchi-Martinez so eloquently stated:

“It is fair to say that the promise of stem cell transplantation is now closer to realization.”