Stem cell stories that caught our eye: sickle cell patient data, vaccine link to leukemia protection, faster cell analysis

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.

Good news from sickle cell clinical trial. It is always satisfying to report positive results from human clinical trials using stem cells even when we don’t fund the work. Bluebird Bio released the first data on a patient treated for sickle cell anemia using the same procedure the company had earlier used to get good outcomes for two patients with beta thalassemia.

Both diseases result from defects—though different defects—in the gene for hemoglobin, the protein our red blood cells use to carry needed oxygen. So, in both cases they use a modified, deactivated virus to carry a correct version of the gene into patients’ own blood-forming stem cells in the lab. They then re-infused those cells into the patients to provide a ready supply of cells able to make the needed protein.

In the sickle cell patient, after the transplant a third of his red cells were making the right protein and that was enough to wean him off blood transfusions that had been keeping him alive and prevented any further hospitalizations due to the disease. The company also announced that the two previously reported patients treated for beta thalassemia had continued to improve. Reuters ran a story on the new data.

CIRM funds a similar project about to begin treating patients for sickle cell disease (link to video), also using a viral vector but a somewhat different one, so it is reassuring to see viral gene carriers working without side effects.

Another reason to vaccinate, prevent leukemia. While it has been known for some time that infant vaccination seems to have driven down the rate of childhood leukemia, no one has known why. A CIRM-funded team at the University of California, San Francisco, thinks they have figured it out. Viral infections trigger inflammation and the production of enzymes in cells that cause genetic mutations that lead to the cancer.

They worked with Haemophilus influenza Type b (Hib) vaccine but suggest a similar mechanism probably applies to other viral infections, and correspondingly, protection from other vaccines. The senior author on the paper, Marcus Muschen, explained the process in a university press release posted at Press-News.org

“These experiments help explain why the incidence of leukemia has been dramatically reduced since the advent of regular vaccinations during infancy. Hib and other childhood infections can cause recurrent and vehement immune responses, which we have found could lead to leukemia, but infants that have received vaccines are largely protected and acquire long-term immunity through very mild immune reactions.”

Barcoding individual cells. Our skin cells all pretty much look the same, but in the palm of your hand there are actually several different types of cells, even a tiny scratch of the fingernail. As scientist work to better understand how cells function, and in particular how stem cells mature, they increasingly need to know precisely what genes are turned on in individual cells.

Both techniques use tiny channels to isolate individual cells and introduce beads with "bar codes."

Both techniques use tiny channels to isolate individual cells and introduce beads with “bar codes.”

Until recently, all this type of analysis blended up a bunch of cells and asked what is in the collective soup. And this did not get the fine-tuned answers today’s scientists are seeking. Numerous teams over the past couple years have reported on tools to get down to single-cell gene analysis. Now, two teams at Harvard have independently developed ways to make this easier. They both use a type of DNA barcode on tiny beads that gets incorporated into individual cells before analysis.

Allan Klein, part of one team based at the Harvard Medical School’s main campus, described why the work is needed in a detailed narrative story released by the school:

“Does a population of cells that we initially think is uniform actually have some substructure. What is the nature of an early developing stem cell? . . . How is [a cell’s] fate determined? “

Even Macosko who worked with the other team centered at the Broad Institute of Harvard and MIT, noted the considerable increase in ease and decrease in cost with the new methods compared to some of the early methods of single cell gene analysis:

“If you’re a biologist with an interesting question in mind, this approach could shine a light on the problem without bankrupting you. It finally makes gene expression profiling on a cell-by-cell level tractable and accessible. I think it’s something biologists in a lot of fields will want to use.”

The narrative provides a good example of what we called the “bump rate” when I was at Harvard Med. Good science often moves forward when scientists bump into each other, and with Harvard Medical faculty scattered at 17 affiliated hospitals and research institutes scattered across Boston and Cambridge we were always looking for ways to increase the bump rate with conferences and cross department events. Macosko and Klein found out they were both working on similar systems at a conference.

Brain’s Own Activity Can Fuel Growth of Deadly Brain Tumors, CIRM-Funded Study Finds

Not all brain tumors are created equal—some are far more deadly than others. Among the most deadly is a type of tumor called high-grade glioma or HGG. Most distressingly, HGG’s are the leading cause of brain tumor death in both children and adults. And despite extraordinary progress in cancer research as a whole, survival rates for those diagnosed with an HGG have yet to improve.

shutterstock_30402241

But recent research from Stanford University scientists could one day help move the needle—and give renewed hope to the patients and their families affected by this devastating disease.

The study, published today in the journal Cell, found that one key driver for HGG’s deadly diagnosis is that the tumor can be stimulated to grow by the brain’s own neural activity—specifically the nerve activity in the brain’s cerebral cortex.

Michelle Monje, senior author of the study that was funded in part by two grants from CIRM, was initially surprised by these results, as they run counter to how most types of tumors grow. As she explained in today’s press release:

“We don’t think about bile production promoting liver cancer growth, or breathing promoting the growth of lung cancer. But we’ve shown that brain function is driving these brain cancers.”
 


By analyzing tumor cells extracted from HGG patients, and engrafting it onto mouse models in the lab, the researchers were able to pinpoint how the brain’s own activity was driving tumor growth.

The culprit: a protein called neuroligin-3 that appeared to be calling the shots. There are four distinct types of HGGs that affect the brain in vastly different ways—and have vastly different molecular and genetic characteristics. Interestingly, says Monje, neuroligin-3 played the same role in all of them.

What was so disturbing to the research team, says Monje, is that neuroligin-3 is an essential protein for overall brain development. Specifically, it helps maintain healthy growth and repair of brain tissue over time. In order to grow, HGG tumors hijack this critical protein.

The research team came to this conclusion after a series of experiments that delved deep into the molecular mechanisms that guide both brain activity and brain tumor development. They first employed a technique called optogenetics, whereby scientists use genetic manipulation to insert light-sensitive proteins into the brain cells, or neurons, of interest. This allowed scientists to activate these neurons—or deactivate them—at the ‘flick of a switch.’

When applying this technique to the tumor-engrafted mouse models, the team could then see that tumors grew significantly better when the neurons were switched on. The next step was to narrow it down to why. Additional biochemical analyses and testing on the mouse models confirmed that neuroligin-3 was being hijacked by the tumor to spur growth.

And when they dug deeper into the connection between neuroligin-3 and cancer, they found something even more disturbing. A detailed look at the Cancer Genome Atlas (a large public database of the genetics of human cancers), they found that HGG patients with higher levels of neuroligin-3 in their brain had shorter survival rates than those with lower levels of the same protein.

These results, while highlighting the particularly nefarious nature of this class of brain tumors, also presents enormous opportunity for researchers. Specifically, Monje hopes her team and others can find a way to block or nullify the presence of neuroligin-3 in the regions surrounding the tumor, creating a kind of barrier that can keep the size of the tumor in check. 


Stem Cell Scientists Reconstruct Disease in a Dish; Gain Insight into Deadly Form of Bone Cancer

The life of someone with Li-Fraumeni Syndrome (LFS) is not a pleasant one. A rare genetic disorder that usually runs in families, this syndrome is characterized by heightened risk of developing cancer—multiple types of cancer—at a very young age.

People with LFS, as the syndrome is often called, are especially susceptible to osteosarcoma, a form of bone cancer that most often affects children. Despite numerous research advances, survival rates for this type of cancer have not improved in over 40 years.

shutterstock_142552177 But according to new research from Mount Sinai Hospital and School of Medicine, the prognosis for these patients may not be so dire in a few years.

Reporting today in the journal Cell, researchers describe how they used a revolutionary type of stem cell technology to recreate LFS in a dish and, in so doing, have uncovered the series of molecular triggers that cause people with LFS to have such high incidence of osteosarcoma.

The scientists, led by senior author Ihor Lemischka, utilized induced pluripotent stem cells, or iPSCs, to model LFS—and osteosarcoma—at the cellular level.

Discovered in 2006 by Japanese scientist Shinya Yamanaka, iPSC technology allows scientists to reprogram adult skin cells into embryonic-like stem cells, which can then be turned into virtually any cell in the body. In the case of a genetic disorder, such as LFS, scientists can transform skin cells from someone with the disorder into bone cells and grow them in the lab. These cells will then have the same genetic makeup as that of the original patient, thus creating a ‘disease in a dish.’ We have written often about these models being used for various diseases, particularly neurological ones, but not cancer.

“Our study is among the first to use induced pluripotent stem cells as the foundation of a model for cancer,” said lead author and Mount Sinai postdoctoral fellow Dung-Fang Lee in today’s press release.

The team’s research centered on the protein p53. P53 normally acts as a tumor suppressor, keeping cell divisions in check so as not to divide out of control and morph into early-stage tumors. Previous research had revealed that 70% of people with LFS have a specific mutation in the gene that encodes p53. Using this knowledge and with the help of the iPSC technology, the team shed much-needed light on a molecular link between LFS and bone cancer. According to Lee:

“This model, when combined with a rare genetic disease, revealed for the first time how a protein known to prevent tumor growth in most cases, p53, may instead drive bone cancer when genetic changes cause too much of it to be made in the wrong place.”

Specifically, the team discovered that the ultimate culprit of LFS bone cancer is an overactive p53 gene. Too much p53, it turns out, reduces the amount of another gene, called H19. This then leads to a decrease in the protein decorin. Decorin normally acts to help stem cells mature into healthy, bone-making cells, known as osteoblasts. Without it, the stem cells can’t mature. They instead divide over and over again, out of control, and ultimately cause the growth of dangerous tumors.

But those out of control cells can become a target for therapy, say researchers. In fact, the team found that artificially boosting H19 levels could have a positive effect.

“Our experiments showed that restoring H19 expression hindered by too much p53 restored “protective differentiation” of osteoblasts to counter events of tumor growth early on in bone cancer,” said Lemischka.

And, because mutations in p53 have been linked to other forms of bone cancer, the team is optimistic that these preliminary results will be able to guide treatment for bone cancer patients—whether they have LFS or not. Added Lemischka:

“The work has implications for the future treatment or prevention of LFS-associated osteosarcoma, and possibly for all forms of bone cancer driven by p53 mutations, with H19 and p53 established now as potential targets for future drugs.”

Learn more about how scientists are using stem cell technology to model disease in a dish in our special video series: Stem Cells In Your Face:

Cancer Cells Mimic Blood Vessels to Colonize the Body’s Farthest Reaches

Scientists at Cold Spring Harbor Laboratory have just uncovered the latest dirty trick in the cancer playbook—one that spurs the cancer cells to spread throughout the body and evade treatment. But importantly, they believe they may have found a way to counter it.

Reporting today in the journal Nature, Cold Spring Harbor researchers describe how tumor cells can form tubular networks that mimic blood vessels. It is this mimicry, the team argues, that plays a key role in helping the cancer spread throughout the body—and a significant hurdle to successfully treating the disease.

Two adjacent sections of a mouse breast tumor. Tissue at left is stained so that normal blood vessels can be seen (black arrow). Extending from these vessels are blood filled channels (green arrows). On the right, the tissue is stained for a fluorescent protein expressed by the tumor cells. Here, blood-filled channels are actually formed by tumor cells in a process known as vascular mimicry. [Credit: Hannon Lab, CSHL]

Two adjacent sections of a mouse breast tumor. Tissue at left is stained so that normal blood vessels can be seen (black arrow). Extending from these vessels are blood filled channels (green arrows). On the right, the tissue is stained for a fluorescent protein expressed by the tumor cells. Here, blood-filled channels are actually formed by tumor cells in a process known as vascular mimicry. [Credit: Hannon Lab, CSHL]

Using mouse models of breast cancer, the team—led by Simon Knott—identified this phenomenon, called ‘vascular mimicry,’ and revealed that two genes, called Serpine2 and Slpi, were driving it. Made up of tumor cells literally stacked together, these tubular networks allowed oxygen and other nutrients to reach far-flung tumor cells throughout the body. This kept the tumor cells healthy, and helped them spread.

In today’s press release, Knott explained his initial reactions to this critical discovery:

“It’s very neat to watch and see cells evolve to have these capacities, but on the other hand it’s really scary to think that these cells are sitting there in people doing this.”

In laboratory experiments, the team found that boosting levels of Serpin2 and Slpi boosted the cancer’s ability to build these networks. Conversely, shutting down these two genes appeared to do the opposite. Knott argues that targeting the proteins that these two genes produce, as a way of shutting them off, may be a winning strategy:

“Targeting them might provide therapeutic benefits,” said Knott, “but we’re not sure yet.”

Indeed, research efforts over the past decade or more have tried to curb the production of these tubular networks of tumor cells, but with limited success. These drugs, called angiogenesis inhibitors, may not have worked as well as originally hoped because the underlying mechanism that creates this vascular mimicry—namely the genes Serpin2 and Slpi—was not targeted. Postdoctoral researcher Elvin Wagenblast, the paper’s first author, thinks they might have more success now:

“Maybe by targeting angiogenesis and also vascular mimicry at the same time we might actually have a better benefit in the clinic in the long run.”

This strategy is ultimately the goal of the team, but much work remains. Their most immediate next steps are to understand the process by which tumor cells pass through these tubular networks and infiltrate new areas of the body. But armed with this new-found knowledge of vascular mimicry, these and other researchers may be well on their way to outsmarting cancer, at least some of the time.

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.”

Shape-Shifting Pancreas Cells Set Stage for Development of Deadly Cancer

After being diagnosed with pancreatic cancer, the likely outcome is—in a word—bleak. At a time when cancers can be treated so successfully as to give the patient a good quality of life, pancreatic cancer remains one of the last holdouts. It is the fourth most deadly form of cancer in the United States. One in four patients won’t last a year.

Pancreatic cancer is one of the most deadly forms of cancer.

Pancreatic cancer is one of the most deadly forms of cancer.

One of the main hurdles for successfully treating this type of cancer is how quickly it spreads. Oftentimes, pancreatic cancer is not diagnosed until having spread to such an extent that even the most aggressive treatments can only delay the inevitable.

As a result, the goal of researchers has been to peer back in time to the origins of pancreatic cancer—in the hopes that they can find a way to halt the disease before it begins to wreak irreversible damage on the body. And now, an international team of researchers believes they have identified a gene that could be the key culprit.

Reporting in the latest issue of Nature Communications, a joint team of scientists from the Mayo Clinic and the University of Oslo, Norway, have pinpointed a gene—called PKD1—that causes normal, healthy pancreatic cells to literally morph into a new, duct-like cell structure. And it is this change in shape that can sometimes lead to pancreatic cancer.

“As soon as pancreatic cancer develops, it begins to spread, and PKD1 is key to both processes,” said Peter Storz, one of the study’s lead authors, in a news release. “Given this finding, we are busy developing a PKD1 inhibitor that we can test further.”

The purpose of the inhibitor, says Storz, is to neutralize PKD1—stopping the cancer in its tracks.

Using pancreatic cells derived from mouse models, the research team tested the effects of PKD1 by turning it on and off at specific intervals, similar to flipping a light switch. In the presence of PKD1, the team observed the pancreas cells rapidly changing shape into the more dangerous, duct-like cells. And when they shut off PKD1, the percentage of cells that underwent shape shifting dropped.

The team’s success at developing this model cannot be understated. As Storz explained:

“This model tells us that PKD1 is essential for the initial transformation…to duct-like cells, which can then become cancerous. If we can stop that transformation from happening—or perhaps reverse the process once it occurs—we may be able to block or treat cancer development and its spread.”

Currently, the teams are developing potential PDK1 inhibitors for further testing—and bring some hope that the prognosis for pancreatic cancer may not always be so dire.

Said Storz: “While these are early days, understanding one of the key drivers in this aggressive cancer is a major step in the right direction.”

Clearing up chemobrain: cancer therapy-induced memory problems reversed by stem cells

You’d think receiving a cancer diagnosis and then suffering through chemo and/or radiation therapy would be traumatic enough. But as many as 75% of cancer survivors are afflicted by memory and attention problems long after their cancer therapy.

This condition, often called “chemobrain”, shouldn’t be misunderstood as being confined to cancers of the brain. A 2012 analysis of nearly 200 women who had been treated with chemotherapy for breast cancer showed they had ongoing memory and information processing deficits that persisted more than twenty years after their last round of treatment. And young cancer survivors are particularly vulnerable to reduced IQs, nonsocial behavior and an extremely lowered quality of life.

uci_news_image_limoli

CIRM grantee and UC Irvine professor Charles Limoli, PhD is senior author of this study

Chemotherapy drugs work by killing off cells that are dividing rapidly, a hallmark of cancer cells. But this brute force method also kills other rapidly dividing cells that are critical for normal bodily functions. In the case of chemobrain, it’s thought that damage to newly formed brain cells in the hippocampus, the memory center of the brain, is the culprit. A UC Irvine study published this week in Cancer Research supports that idea in experiments that test the effect of transplanting human nerve stem cells in rats. The research team leader Charles Limoli, a CIRM grantee and UC Irvine professor of radiation oncology, summarized the groundbreaking results in a press release (note: this study is not funded by CIRM):

“Our findings provide the first solid evidence that transplantation of human neural stem cells can be used to reverse chemotherapeutic-induced damage of healthy tissue in the brain.”

The novel place recognition test is evaluate memory function. Animal is initially presented with identical objects (red circles). Then a new object is introduced (blue square). A healthy mouse will investigate the blue square.

The novel place recognition test, one of several tests used in this study to evaluate memory function.  During training setup (left), the rodent is familiarized with identical objects (red circles). Later, rodent returns now in presence of a new object (blue square). A healthy mouse will investigate the new object during testing setup (right). Image credit: KnowingNeurons.com

So how the heck do you observe chemotherapy-induced cognitive problems in a rodent let alone show that stem cells can rescue the damage? In the study, the rats undergo a variety of recognition memory tasks after a typical chemotherapy drug treatment. For instance, in the novel place recognition test, an animal is familiarized with two identical objects inside a test “arena”. Later, the animal is returned to the arena but a new object is swapped in for one of the previous objects. Rats given chemotherapy treatment but no stem cell surgery (they’re implanted with a saline solution instead) do not show a preference for the novel object. But rats given chemotherapy and the human nerve stem cell surgery prefer the novel object. This novel seeking behavior is also seen in control rats given no chemotherapy. So these results demonstrate that the transplanted stem cells rescued normal memory recognition in the chemotherapy-treated rats.

The research team also saw differences within the brains of these groups of rats that match up with these behavioral results. First, they confirmed that the transplanted human stem cells had indeed survived and grafted into the rat brains and had matured into the correct type of brain cells. Next they looked at chemotherapy-induced inflammation of brain tissue. The brains of chemotherapy-treated rats with no stem cell transplantation showed increased number of active immune cells compared to the control and stem cell transplanted animals. In another experiment, a detailed analysis of the structure of individual nerve cells showed extensive damage in the chemotherapy treated rats compared to controls. Again, this damage was reversed in chemotherapy treated rats that also received the stem cell transplant.

Rat nerve cells (black structures) in memory center of the brain are damaged by chemotherapy (left); transplanting human nerve stem cells reverses the damage (right)

Rat nerve cells (black structures) in memory center of the brain are damaged by chemotherapy (left); transplanting human nerve stem cells reverses the damage (right). Image credit: Acharya et al. Cancer Research 75(4) p. 676

As many researchers can tell you, these exciting results in animals don’t guarantee a human therapy is around the corner. But still, says Limoli:

“This research suggests that stem cell therapies may one day be implemented in the clinic to provide relief to patients suffering from cognitive impairments incurred as a result of their cancer treatments. While much work remains, a clinical trial analyzing the safety of such approaches may be possible within a few years.”

For a more details about the role of stem cells in chemobrain, watch this recent presentation to the CIRM Governing Board by CIRM grantee and Stanford professor Michelle Monje.

Combination Cancer Therapy Gives Cells a Knockout Punch

For some forms of cancer, there really is no way to truly eradicate it. Even the most advanced chemotherapy treatments leave behind some straggler cells that can fuel a relapse.

By hitting breast cancer cells with a targeted therapeutic immediately after chemotherapy, researchers were able to target cancer cells during a transitional stage when they were most vulnerable. [Credit: Aaron Goldman]

By hitting breast cancer cells with a targeted therapeutic immediately after chemotherapy, researchers were able to target cancer cells during a transitional stage when they were most vulnerable.
[Credit: Aaron Goldman]

But now, scientists have devised a unique strategy, something they are calling a ‘one-two punch’ that can more effectively wipe out dangerous tumors, and lower the risk of them ever returning for a round two.

Reporting in the latest issue of the journal Nature Communications, bioengineers at Brigham and Women’s Hospital (BWH) in Boston describe how treating breast cancer cells with a targeted drug immediately after chemotherapy was effective at killing the cancer cells and preventing a recurrence. According to lead scientist Shiladitya Sengupta, these findings were wholly unexpected:

“We were studying the fundamentals of how [drug] resistance develops and looking to understand what drives [cancer] relapse. What we found is a new paradigm for thinking about chemotherapy.”

In recent years, many scientists have suggested cancer stem cells are one of the biggest hurdles to curing cancer. Cancer stem cells are proposed to be a subpopulation of cancer cells that are resistant to chemotherapy. As a result, they can propagate the cancer after treatment, leading to a relapse.

In this work, Sengupta and his colleagues treated breast cancer cells with chemotherapy. And here is where things started getting interesting.

After chemotherapy, the breast cancer cells began to morph into cells that bore a close resemblance to cancer stem cells. For a brief period of time after treatment, these cells were neither fully cancer cells, nor fully stem cells. They were in transition.

The team then realized that because these cells were in transition, they may be more vulnerable to attack. Testing this hypothesis in mouse models of breast cancer, the team first zapped the tumors with chemotherapy. And, once the cells began to morph, they then blasted them with a different type of drug. The tumors never grew back, and the mice survived.

Interestingly, the team did not have similar success when they altered the timing of when they administered the therapy. Treating the mice with both types of drugs simultaneously didn’t have the same effect. Neither did increasing the time between treatments. In order to successfully treat the tumor they had a very slim window of opportunity.

“By treating with chemotherapy, we’re driving cells through a transition state and creating vulnerabilities,” said Aaron Goldman, the study’s first author. “This opens up the door: we can then try out different combinations and regimens to find the most effective way to kill the cells and inhibit tumor growth.”

In order to test these combinations, the researchers developed an ‘explant,’ a mini-tumor derived from a patient’s biopsy that can be grown in an environment that closely mimics its natural surroundings. The ultimate goal, says Goldman, is to map the precise order and timing of this treatment regimen in order to move toward clinical trials:

“Our goal is to build a regimen that will be [effective] for clinical trials. Once we’ve understood specific timing, sequence of drug delivery and dosage better, it will be easier to translate these findings clinically.”

Stem cell stories that caught our eye: repairing radiation damage, beta thalassemia clinical trial and disease models

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

Stem cells repair brain damage from radiation therapy. Radiation for brain cancer can be a lifesaver but it can also be a dramatic life changer. If often leaves patients with considerably reduced brain function. Now a team at New York’s Memorial Sloan Kettering Cancer Center has found a way to instruct human stem cells to repair some of that damage—at least in rats.

The damage seems to be to the middle-man or so-called progenitor cells that maintain the myelin cells that insulate the nerves in the brain. When that myelin is damaged by the radiation those progenitor cells are no longer able to make repairs and that results in reduced nerve function. Rats given the stem cells regained both cognitive and motor skills lost after brain radiation.

The team leader, Viviane Taber, noted this work could make radiation therapy even more of a lifesaver. ScienceDaily quoted Tabar from materials provided by Cell Press that published the work:

“This will have to be proven further, but if we can repair the brain effectively, we could be bolder with our radiation dosing, within limits.”

This could be especially important in children, for whom physicians deliberately deliver lower radiation doses.


Stem cell trial for Beta-Thalassemia cleared to begin.
CIRM-grantee Sangamo BioSciences announced this week that the Food and Drug Administration (FDA) had accepted its application to begin a clinical trial using genetically edited stem cells to treat patients with beta-thalassemia. This trial, in patients who require regular blood transfusions to survive, is the ninth CIRM-funded clinical trail to gain clearance from the FDA.

Other clinical trials have used genetically modified stem cells, but they have used various techniques to add a correct gene or silence an unwanted gene. This will be the first clinical trial using one of the newer techniques that actually goes into a person’s genes and edits them to correct a disease. We wrote about this beta-thalassemia project here.

The Sacramento Business Times picked up the company’s press release that quoted Sangamo president Edward Lanphier on the company’s goal, “the aim of providing transfusion-dependent beta-thalassemia patients with a one-time treatment for this devastating disease.”

Disease modeling for science wonks. Vivien Marx wrote a feature article for Nature Methods that provides the most thorough review of the use of reprogramed iPS-type stem cells as disease models that I have read. In particular she discusses the power of using new gene editing tools to modify the cells so that when they mature into adult tissues they will display specific disease traits.

Svendsen hopes to use gene-edited iPS type stem cells to fully understand neurodegenerative diseases

Svendsen hopes to use gene-edited iPS type stem cells to fully understand neurodegenerative diseases

She starts with a narrative about CIRM-grantee Clive Svendsen’s work to understand spinal muscular atropohy (SMA) when he was in Wisconsin and to understand amyotrophic lateral sclerosis (ALS) now at Cedars Sinai in Los Angeles. She goes on to show just how powerful these gene-edited stem cells can be, but also how difficult it is to use the technology in a way that generates useful information. Marx is a strong science journalist, who for many years has shown a skill at explaining complex technologies.

She also discusses the various iPS cell banks developed around the world including CIRM’s cell bank and the value of having non-gene-edited cells from patients that naturally show the disease traits.

Thorough review of changes at CIRM.
Alex Lash at xconomy wrote an in-depth overview of our president Randy Mills’ plans for the next phase of our agency that Randy calls CIRM 2.0. Calling the plans an extensive “renovation” Lash described the portions of the new structure that were already in place and listed the ones set to come online in the next six months.

As a balanced journalist he runs through some of the highs and lows of our public perception during the initial phase of the agency and then discusses the new tone set by Mills:

“CIRM is less a grant-making government agency than a ‘discerning investor’ that’s going to be ‘as creative and innovative’ as possible in getting treatments approved, Mills says. ‘We have no mission above accelerating stem cell therapies to patients.’ ”

In living color: new imaging technique tracks traveling stem cells

Before blood stem cells can mature, before they can grow and multiply into the red blood cells that feed our organs, or the white blood cells that protect us from pathogens, they must go on a journey.

A blood stem cell en route to taking root in a zebrafish. [Credit: Boston Children's Hospital]

A blood stem cell en route to taking root in a zebrafish. [Credit:
Boston Children’s Hospital]

This journey, which takes place in the developing embryo, moves blood stem cells from their place of origin to where they will take root to grow and mature. That this journey happened was well known to scientists, but precisely how it happened remained shrouded in darkness.

But now, for the first time, scientists at Boston Children’s Hospital have literally shone a light on the entire process. In so doing, they have opened the door to improving surgical procedures that also rely on the movement of blood cells—such as bone marrow transplants, which are in essence stem cell transplants.

Reporting in today’s issue of the journal Cell, Boston Children’s senior investigator Leonard Zon and his team developed a way to visually track the trip that blood stem cells take in the developing embryo. As described in today’s news release, the same process that guides blood stem cells to the right place also occurs during a bone marrow transplant. The similarities between the two, therefore, could lead to more successful bone marrow transplants. According to the study’s co-first author Owen Tamplin:

“Stem cell and bone marrow transplants are still very much a black box—cells are introduced into a patient and later on we can measure recovery of the blood system, but what happens in between can’t be seen. Now we have a system where we can actually watch that middle step.”

And in the following video, Zon describes exactly how they did it:

As outlined in the above video, Zon and his team developed a transparent version of the zebrafish, a tiny model organism that is often used by scientists to study embryonic development. They then labeled blood stem cells in this transparent fish with a special fluorescent dye, so that the cells glowed green. And finally, with the help of both confocal and electron microscopy, they sat back and watched the blood stem cell take root in what’s called its niche—in beautiful Technicolor.

“Nobody’s ever visualized live how a stem cell interacts with its niche,” explained Zon. “This is the first time we get a very high-resolution view of the process.”

Further experiments found that the process in zebrafish closely resembled the process in mice—an indication that the same basic system could exist for humans.

With that possibility in mind, Zon and his team already have a lead on a way to improve the success of human bone marrow transplants. In chemical screening experiments, the team identified a chemical compound called lycorine that boosts the interaction between the zebrafish blood stem cell and its niche—thus promoting the number of blood stem cells as the embryo matures.

Does the lycorine compound (or an equivalent) exist to boost blood stem cells in mice? Or even in humans? That remains to be seen. But with the help of the imaging technology used by Zon and the Boston Children’s team—they have a good chance of being able to see it.