Cancer-causing mutations in blood stem cells may also link to heart disease

Whether we read about it in the news or hear it from our doctor, when we think about the causes of heart disease it’s usually some combination of inheriting bad genes from our parents and making poor life style choices like smoking or eating a diet high in fat and cholesterol. But in a fascinating research published yesterday in the New England Journal of Medicine, scientists show evidence that in some people, heart disease may develop much in the same way that a blood cancer does; that is, through a gradual, lifetime accumulation of mutations in hematopoietic cells, or blood stem cells.

This surprising discovery began as a project, published in 2014, aimed at early detection of blood cancers in the general population. This earlier study focused on the line of evidence that cells don’t become cancerous overnight but rather progress slowly as we age. So, in the case of a blood cancer, or leukemia, a blood stem cell can acquire a mutation that transforms the cell into a pre-cancerous state. When that stem cell multiplies it creates “clones” of the blood stem cell that had the cancer-initiating mutation. It’s only after additional genetic insults that these stem cells become full blown cancers.

The research team, composed of scientists from Brigham and Women’s Hospital as well as the Broad Institute of Harvard and MIT, examined DNA sequences from blood samples of over 17,000 people who didn’t have blood cancer. They analyzed these samples, specifically looking at 160 genes that are often mutated in blood cancer. The results from the 2014 study showed that mutations in these genes in people 40 years and under were few and far between. Interestingly, the frequency noticeably increased in older folks with those 10% over 70 years of age carrying the mutations.

Most of these so-called “clonal hematopoiesis of indeterminate potential”, or CHIP, mutations occurred in three genes called DNMT3A, TET2, and ASXL1. While these mutations were indeed associated with a 10-fold higher risk of blood cancer, the team also saw an unexpected correlation: people with these mutations had a 40% higher overall risk of dying due to other causes compared to those who did not carry the mutations. They pinpointed heart disease as one primary cause of the increased mortality risk.

The current follow-up study not only sought to confirm this correlation between the mutations and heart disease but also show the mutations cause the increased risk. This time around, the team looked for the mutations in a group of four different populations totaling over 8000 people. Again, they saw a correlation between the mutations and the risk of heart disease or a heart attack later in life. One of the team leads, Dr. Sekar Kathiresan from the Broad Institute, talked about his team’s reaction to these results in a Time Magazine interview:

Sekar Kathiresan, Photo: Broad Institute

“We were fully expecting not to find anything here. But the odds of having an early heart attack are four-fold higher among younger people with CHIP mutations.”

 

To show a causal link, they turned to mouse studies. They collected bone marrow stem cells from mice engineered to lack Tet2, one of the three genes that when mutated had been associated with increased risk of heart disease. The bone marrow cells were then transplanted into mice which are prone to have increased blood cholesterol and symptoms of heart disease. The presence of these cells that lacked Tet2 led to increased hardening of major arteries – a precursor to clogged blood vessels, heart disease and heart attacks – compared to mice that received normal bone marrow cells.

Though more work remains, Kathiresan thinks these current results offer some tantalizing therapeutic possibilities:

“This is a totally different type of risk factor than hypertension or hypercholestserolemia [high blood cholesterol] or smoking. And since it’s a totally different risk factor that works through a different mechanism, it may lead to new treatment opportunities very different from the ones we have for heart disease at present.”

4 things to know about stem cell clinical trials [Video]

Every day, we receive phone calls and emails from people who are desperately seeking our help. Sometimes they reach out on their own behalf, though often it’s for a family member or close friend. In every case, someone is suffering or dying from a disorder that has no available cure or effective treatment and they look to stem cell treatments as their only hope.

It’s heartbreaking to hear these personal stories that are unfolding in real time. Though they contact us from a wide range of places about a wide range of disorders, their initial set of questions are often similar and go something like this:

  • “Where can I find stem cell clinical trial for my condition?”
  • “What are my chances of being cured?”
  • “How much does it cost to be in a clinical trial?”
  • “How can I be sure it’s safe?”

We think anyone thinking about taking part in a clinical trial should consider these important questions. So, in addition to providing answers as we receive them through phone calls and emails, we wanted to find a way to reach out to as many people as possible. The result? The four-minute animation video you can watch below:

As mentioned in the video, the answers to these questions are only the tip of the iceberg for finding out if a particular clinical trial is right for you. The website, A Closer Look at Stem Cells, produced by the International Society for Stem Cell Research (ISSCR), is an excellent source for more advice on what things you should know before participating in a stem cell clinical trial or any experimental stem cell treatment.

And visit the Patient Resources section of our website for even more practical information including our growing list of CIRM-funded clinical trials as well as trials supported by our Alpha Stem Cell Clinic Network.

Nine months in, stem cell-based therapy for spinal cord injury continues to improve paralyzed patients’ lives

If you’ve been following the Stem Cellar blog this year, then you must be as encouraged as we are with Asterias Biotherapeutics’ CIRM-funded clinical trial, which is testing an embryonic stem cell-based therapy for spinal cord injury.

astopc1Over many months, we’ve covered the company’s string of positive announcements that their cell therapy product – called AST-OPC1 – appears safe, is doing what is it’s supposed to after injection into the damaged spinal cord, and shows signs of restoring upper body function at 3 and 6 months after treatment. We’ve also written about first-hand accounts from some of the clinical trial participants who describe their remarkable recoveries.

That streak of good news continues today with Asterias’ early morning press release. The announcement summarizes 9-month results for a group of six patients who received an injection of 10 million AST-OPC1 cells 2 to 4 weeks after their injury (this particular trial is not testing the therapy on those with less recent injuries). In a nut shell, their improvements in arm, hand and finger movement seen at the earlier time points have persisted and even gotten better at 9 months.

Two motors levels = a higher quality of life
These participants sustained severe spinal cord injuries in the neck, leading to a loss of feeling and movement in their body from the neck down. To quantify the results of the cell therapy, researchers refer to “motor levels” of improvement. These levels correspond to an increasing number of motor, or movement, abilities. For a spinal cord injury victim paralyzed from the neck down, recovering two motor levels of function can mean the difference between needing 24-hour a day home care versus dressing, feeding and bathing themselves. The impact of this level of improvement cannot be overstated. As mentioned in the press release, regaining these abilities, “can result in lower healthcare costs, significant improvements in quality of life, increased ability to engage in activities of daily living, and increased independence.”

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9-month follow-up results of Asterias’ spinal cord injury trial. Patients treated with stem cell-based therapy (green line) have greater movement recovery compared to historical data from 62 untreated patients (Blue dotted line). Image: Asterias Biotherapeutics.

With the new 9-month follow-up data, the clinical researchers have confirmed that 3 out of the 6 (50%) patients show two motor levels of improvement. This result is up from 2 of 6 patients at the earlier time points. And all six patients have at least one motor level of improvement up through 9 months post-treatment. Now, make no mistake, spontaneous recovery from spinal cord injuries does occur. But historical data collected from 62 untreated patients show that only 29% reached two motor levels of improvement after 12-months.

As you can imagine, the Asterias team is optimistic about these latest results. Here’s what Chief Medical Officer, Dr. Edward Wirth had to say:

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Edward Wirth
Photo: Asterias

“The new efficacy results show that previously reported meaningful improvements in arm, hand and finger function in the 10 million cell cohort treated with AST-OPC1 cells have been maintained and in some patients have been further enhanced even 9 months following dosing. We are increasingly encouraged by these continued positive results, which are remarkable compared with spontaneous recovery rates observed in a closely matched untreated patient population.”

Equally encouraging is the therapy’s steady safety profile with no serious adverse events reported through the 9-month follow up.

Looking ahead
Dr. Jane Lebkowski, Asterias’ President of R&D and Chief Scientific Officer, will be presenting these data today during the International Society for Stem Cell Research (ISSCR) 2017 Annual Meeting held in Boston. Asterias expects to share more results later this fall after all six patients complete their 12-month follow-up visit.

The clinical trial is also treating another group of patients with a maximum dose of 20 million cells. The hope is that this cohort will show even more effectiveness.

For the sake of the more than 17,000 people who are incapacitated by a severe spinal cord injury each year, let’s hope the streak of good news continues.

Stories that caught our eye: color me stem cells, delivering cell therapy with nanomagnets, and stem cell decisions

Nanomagnets: the future of targeted stem cell therapies? Your blood vessels are made up of tightly-packed endothelial cells. This barrier poses some big challenges for the delivery of drugs via the blood. While small molecules are able make their way through the small gaps in the blood vessel walls, larger drug molecules, including proteins and cells, are not able to penetrate the vessel to get therapies to diseased areas.

This week, researchers at Rice University report in Nature Communications on an ingenious technique using tiny magnets that may overcome this drug delivery problem.

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At left, the nanoparticles are evenly distributed among the microtubules that help give the cells their shape. At right, after a magnetic field is applied, the nanoparticles are pulled toward one end of the cells and change their shapes. Credit: Laboratory of Biomolecular Engineering and Nanomedicine/Rice University

Initial studies showed that adding magnetic nanoparticles to the endothelial cells and then applying a magnetic field affected the cells’ internal scaffolding, called microtubules. These structures are responsible for maintaining the tight cell to cell connections. The team took the studies a step further by growing the cells in specialized petri dishes containing tiny, tube-shaped channels. Applying a magnetic field to the cells caused the cell-cell junctions to form gaps, making the blood vessel structures leaky. Simply turning off the magnetic field closed up the gaps within a few hours.

Though a lot of research remains, the team aims to apply this on-demand induction of cell leakiness along with adding the magnetic nanoparticles to stem cell therapy products to help target the treatment to specific area. In a press release, team leader Dr. Gang Bao spoke about possible applications to arthritis therapy:

“The problem is how to accumulate therapeutic stem cells around the knee and keep them there. After injecting the nanoparticle-infused cells, we want to put an array of magnets around the knee to attract them.”

To differentiate or not differentiate: new insights During the body’s development, stem cells must differentiate, or specialize, into functional cells – like liver, heart, brain. But once that specialization occurs, the cells lose their pluripotency, or the ability to become any type of cell. So, stem cells must balance the need to differentiate with the need to make copies of itself to maintain an adequate supply of stem cells to complete the development process. And even after a fully formed baby is born, it’s still critical for adult stem cells to balance the need to regenerate damaged tissue versus stashing away a pool of stem cells in various organs for future regeneration and replacement of damaged or diseased tissues.

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Visualizing activation of Nanog gene activity (bright green spot) within cell nucleus. 
Image: Courtesy of Bony De Kumar, Ph.D., and Robb Krumlauf, Ph.D., Stowers Institute for Medical Research

A report this week in the Proceedings of the National Academy of Sciences finds evidence that the two separate processes – differentiation and pluripotency – directly communicate with each other as way to ensure a proper balance between the two states.

The study, carried out by researchers at Stowers Institute for Medical Research in Kansas City, Missouri, focused on the regulation of two genes: Nanog and Hox. Nanog is critical for maintaining a stem cell’s ability to become a specialized cell type. In fact, it’s one of the four genes initially used to reprogram adult cells back into induced pluripotent stem cells. The Hox gene family is responsible for generating a blueprint of the body plan in a developing embryo. Basically, the pattern of Hox gene activity helps generate the body plan, basically predetermining where the various body parts and organs will form.

Now, both Nanog and Hox proteins act by binding to DNA and turning on a cascade of other genes that ultimately maintain pluripotency or promote differentiation. By examining these other genes, the researchers were surprised to find that both Nanog and Hox were bound to both the pluripotency and differentiation genes. They also found that Nanog and Hox can directly inhibit each other. Taken together, these results suggest that exquisite control of both processes occurs cross regulation of gene activity.

Dr. Robb Krumlauf one of authors on the paper talked about the significance of the result in a press release:

“Over the past 10 to 20 years, biologists have shown that cells are actively assessing their environment, and that they have many fates they can choose. The regulatory loops we’ve found show how the dynamic nature of cells is being maintained.”

Color me stem cells Looking to improve your life and the life of those around you? Then we highly recommend you pay a visit to today’s issue of Right Turn, a regular Friday feature of  Signals, the official blog of CCRM, Canada’s public-private consortium supporting the development of regenerative medicine technologies.

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Collage sample of CCRM’s new coloring sheets. Image: copyright CCRM 2017

As part of an public outreach effort they have created four new coloring sheets that depict stem cells among other sciency topics. They’ve set up a DropBox link to download the pictures so you can get started right away.

Adult coloring has swept the nation as the hippest new pastime. And it’s not just a frivolous activity, as coloring has been shown to have many healthy benefits like reducing stressed and increasing creativity. Just watch any kid who colors. In fact, share these sheet with them, it’s intended for children too.

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

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

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

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

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

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

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

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

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

“A limitless future”: young crash victim regains hand, finger movement after CIRM-funded trial

Back in March, we reported on Asterias Biotherapeutics’ exciting press release stating that its CIRM-funded stem cell-based therapy for spinal cord injury had shown improvement in six out of the six clinical trial patients receiving a ten million cell dose. What’s even more exciting is hearing stories about the positive impact of that data on specific people’s lives. People like Lucas Lindner of Eden, Wisconsin.

Lucas Lindner was left paralyzed below the chin after a truck accident last May. Photo: Fox6Now, Milwaukee

Just over a year ago, Lucas headed out in his truck on a Sunday morning to pick up some doughnuts for his grandmother. Along the way, he suddenly saw a deer in the road and, in swerving to avoid hitting the animal, Lucas’ truck flipped over. He was thrown through the window and suffered a severe spinal cord injury leaving him without the use of his arms and legs.

Linder was the 2nd person to receive a 10 million dose of Asterias’ CIRM-funded stem cell-based therapy for spinal cord injury. Video still: Fox6Now, Milwaukee

Earlier this month, Lucas was featured in a local Milwaukee TV news report that highlights his incredible recovery since participating in the Asterias trial shortly after his accident. Surgeons at Medical College of Wisconsin – one of the clinical trial sites – injected 10 million AST-OPC1 cells into the site of the spinal cord injury a few inches below his skull. The AST-OPC1 product contains oligodendrocyte progenitor cells, which when fully matured are thought to help restore nerve signaling in the frayed spinal cord nerve cells.

Lucas was just the second person nationally to receive the 10 million cell dose, and since that time, he’s regained movement in his arms, hands and fingers. This improvement may seem moderate to an outside observer, but for Lucas, it’s life changing because it gives him the independence to pursue his dreams of working in the IT and electronics fields:

“Now that I have near 100% full range on all of my fingers, that pretty much brings everything I ever wanted to do back. It lets you contribute to society. Words can’t express how amazing it feels…The future really is limitless,” he said during the TV new segment.

While regaining movement spontaneously without a stem cell treatment is not unheard of, the fact that all six of the trial participants receiving 10 million cells had improvements suggests the stem cell-based therapy is having a positive impact. We’re hopeful for further good news later this year when Asterias expects to provide more safety and efficacy data on participants given the 10 million cell dose as well as others who received the maximum 20 million cell dose.

Stem cell stories that caught our eye: new baldness treatments?, novel lung stem cells, and giraffe stem cells

Novel immune system/stem cell interaction may lead to better treatments for baldness. When one thinks of the immune system it’s usually in terms of the body’s ability to fight off a bad cold or flu virus. But a team of UCSF researchers this week report in Cell that a particular cell of the immune system is key to instructing stem cells to maintain hair growth. Their results suggest that the loss of these immune cells, called regulatory T cells (Tregs for short), may be the cause of baldness seen in alopecia areata, a common autoimmune disorder and may even play a role in male pattern baldness.

Alopecia, a common autoimmune disorder that causes baldness. Image: Shutterstock

While most cells of the immune system recognize and kill foreign or dysfunctional cells in our bodies, Tregs act to subdue those cells to avoid collateral damage to perfectly healthy cells. If Tregs become impaired, it can lead to autoimmune disorders in which the body attacks itself.

The UCSF team had previously shown that Tregs allow microorganisms that are beneficial to skin health in mice to avoid the grasp of the immune system. In follow up studies they intended to examine what happens to skin health when Treg cells were inhibited in the skin of the mice. The procedure required shaving away small patches of hair to allow observation of the skin. Over the course of the experiment, the scientists notice something very curious. Team lead Dr. Michael Rosenblum recalled what they saw in a UCSF press release:

“We quickly noticed that the shaved patches of hair never grew back, and we thought, ‘Hmm, now that’s interesting. We realized we had to delve into this further.”

That delving showed that Tregs are located next to hair follicle stem cells. And during the hair growth, the Tregs grow in number and surround the stem cells. Further examination, found that Tregs trigger the stem cells through direct cell to cell interactions. These mechanisms are different than those used for their immune system-inhibiting function.

With these new insights, Dr. Rosenblum hopes this new-found role for Tregs in hair growth may lead to better treatments for Alopecia, one of the most common forms of autoimmune disease.

Novel lung stem cells bring new insights into poorly understood chronic lung disease. Pulmonary fibrosis is a chronic lung disease that’s characterized by scarring and changes in the structure of tiny blood vessels, or microvessels, within lungs. This so-called “remodeling” of lung tissue hampers the transfer of oxygen from the lung to the blood leading to dangerous symptoms like shortness of breath. Unfortunately, the cause of most cases of pulmonary fibrosis is not understood.

This week, Vanderbilt University Medical Center researchers report in the Journal of Clinical Investigation the identification of a new type of lung stem cell that may play a role in lung remodeling.

Susan Majka and Christa Gaskill, and colleagues are studying certain lung stem cells that likely contribute to the pathobiology of chronic lung diseases.  Photo by: Susan Urmy

Up until now, the cells that make up the microvessels were thought to contribute to the detrimental changes to lung tissue in pulmonary fibrosis or other chronic lung diseases. But the Vanderbilt team wasn’t convinced since these microvessel cells were already fully matured and wouldn’t have the ability to carry out the lung remodeling functions.

They had previously isolated stem cells from both mouse and human lung tissue located near microvessels. In this study, they tracked these mesenchymal progenitor cells (MPCs) in normal and disease inducing scenarios. The team’s leader, Dr. Susan Majka, summarized the results of this part of the study in a press release:

“When these cells are abnormal, animals develop vasculopathy — a loss of structure in the microvessels and subsequently the lung. They lose the surfaces for gas exchange.”

The team went on to find differences in gene activity in MPCs from healthy versus diseased lungs. They hope to exploit these differences to identify molecules that would provide early warnings of the disease. Dr. Majka explains the importance of these “biomarkers”:

“With pulmonary vascular diseases, by the time a patient has symptoms, there’s already major damage to the microvasculature. Using new biomarkers to detect the disease before symptoms arise would allow for earlier treatment, which could be effective at decreasing progression or even reversing the disease process.”

The happy stem cell story of Mahali the giraffe. We leave you this week with a feel-good story about Mahali, a 14-year old giraffe at the Cheyenne Mountain Zoo in Colorado. Mahali had suffered from chronic arthritis in his front left leg. As a result, he could not move well and was kept isolated from his herd.

Giraffes at Cheyenne Mountain Zoo. Photo: Denver Post

The zoo’s head veterinarian, Dr. Liza Dadone, decided to try a stem cell therapy procedure to bring Mahali some relief and a better quality of life. It’s the first time such a treatment would be performed on a giraffe. With the help of doctors at Colorado State University’s James L. Voss Veterinary Teaching Hospital, 100 million stem cells grown from Mahali’s blood were injected into his arthritic leg.

Before treatment, thermograph shows inflammation (red/yellow) in Mahali’s left front foot (seen at far right of each image); after treatment inflammation resolved (blue/green). Photos: Cheyenne Mountain Zoo

In a written statement to the Colorado Gazette, Dr. Dadone summarized the positive outcome:

“Prior to the procedure, he was favoring his left front leg and would lift that foot off the ground almost once per minute. Since then, Mahali is no longer constantly lifting his left front leg off the ground and has resumed cooperating for hoof care. A few weeks ago, he returned to life with his herd, including yard access. On the thermogram, the marked inflammation up the leg has mostly resolved.”

Now, Dr. Dadone made sure to state that other treatments and medicine were given to Mahali in addition to the stem cell therapy. So, it’s not totally clear to what extent the stem cells contributed to Mahali’s recovery. Maybe future patients will receive stem cells alone to be sure. But for now, we’re just happy for Mahali’s new lease on life.

New target for defeating breast cancer stem cells uncovered

Stashed away in most of your tissues and organs lie small populations of adult stem cells. They help keep our bodies functioning properly by replenishing dying or damaged cells. Their ability to make more copies of themselves, as needed, ensures that there’s always an adequate supply set aside. But this very same self-renewing, life-sustaining property of adult stem cells is deadly in the hands of cancer stem cells. Also called tumor-initiating cells, cancer stem cells sustain tumor growth even after chemotherapy and are thought to be a primary cause of cancer relapse.

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Microscopic image of normal mouse mammary ducts. Mammary stem cells are found among basal cells (green). Image courtesy of Toni Celià-Terrassa and Yibin Kang, Princeton University

By studying adult and cancer stem cells side-by-side, Princeton researchers report this week in Nature Cell Biology that they’ve uncovered a common function in both cells types that not only helps explain an adult stem cell’s self-renewing ability but also points to new therapeutic approaches to targeting breast cancer stem cells.

Both adult and cancer stem cells continually resist signals from their environment that encourage them to specialize, or differentiate, into a particular cell type. Once specialized, the cells lose their ability to self-renew and will eventually die off. Now, if all the adult stem cells in an organ followed that instruction, they would eventually become depleted and the organ would lose the ability to repair itself. The same holds true for cancer stem cells which actually would be a good thing since it would lead to the tumor’s death.

The Princeton team first identified a molecule called miR-199a that allows mammary (breast) stem cells to resist differentiation signals by directly blocking the production of a protein called LCOR. Artificially boosting the amount of miR-199a led to a decrease in LCOR levels and an increase in stem cell function. But when LCOR levels were increased, mammary stem cell function was restricted.

The researchers then turned their attention to breast cancer stem cells and found the same miR-199a/LCOR function at work. In a similar fashion, boosting miR-199a levels enhanced cancer stem cell function and increased tumor formation while increasing LCOR restricted the tumor-forming ability of the breast cancer stem cells.

These lab results also matched up with tissue samples taken from breast cancer patients. High miR-199a levels in the samples correlated with low patient survival rates. But those with high levels of LCOR showed a better prognosis.

It turns out that cells in our immune system are responsible for boosting LCOR in mammary and breast cancer stem cells by releasing a protein called interferon alpha. So the presence of interferon alpha nudges mammary stem cells to mature into mammary gland cells and inhibits breast cancer stems from forming tumors. But in the presence of elevated miR-199a levels, mammary and breast cancer stem cells are protected and maintain their numbers by deactivating the interferon alpha/LCOR signal.

If you’re still with me, these results point to miR-199a as a promising target for restoring interferon-alpha’s cancer interfering properties. Team leader Dr. Yibin Kang highlighted this possibility in a Princeton University press release:

“Interferons have been widely used for the treatment of multiple cancer types. These treatments might become more effective if the interferon-resistant cancer stem cells can be rendered sensitive by targeting the miR-199a-LCOR pathway.”

Stem cell-derived blood-brain barrier gives more complete picture of Huntington’s disease

Like a sophisticated security fence, our bodies have evolved a barrier that protects the brain from potentially harmful substances in the blood but still allows the entry of essential molecules like blood sugar and oxygen. Just like in other parts of the body, the blood vessels and capillaries in the brain are lined with endothelial cells. But in the brain, these cells form extremely tight connections with each other making it nearly impossible for most things to passively squeeze through the blood vessel wall and into the brain fluid.

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Compared to blood vessels in other parts of the body, brain blood vessels form a much tighter seal to protect the brain.
Image source: Dana and Chris Reeve Foundation

Recent studies have shown defects in the brain-blood barrier are associated with neurodegenerative disorders like Huntington’s disease and as a result becomes leakier. Although the debilitating symptoms of Huntington’s disease – which include involuntary movements, severe mood swings and difficulty swallowing – are primarily due to the gradual death of specific nerve cells, this breakdown in the blood-brain barrier most likely contributes to the deterioration of the Huntington’s brain.

What hasn’t been clear is if mutations in Huntingtin, the gene that is linked to Huntington’s disease, directly impact the specialized endothelial cells within the blood-brain barrier or if these specialized cells are just innocent bystanders of the destruction that occurs as Huntington’s progresses. It’s an important question to answer. If the mutations in Huntingtin directly affect the blood-brain barrier then it could provide a bigger picture of how this incurable, fatal disease works. More importantly, it may provide new avenues for therapy development.

A UC Irvine research team got to the bottom of this question with the help of induced pluripotent stem cells (iPSCs) derived from the skin cells of individuals with Huntington’s disease. Their CIRM-funded study was published this week in Cell Reports.

In a first for a neurodegenerative disease, the researchers coaxed the Huntington’s disease iPSCs in a lab dish to become brain microvascular endothelial cells (BMECs), the specialized cells responsible for forming the blood-brain barrier. The researchers found that the Huntington’s BMECs themselves were indeed dysfunctional. Compared to BMECs derived from unaffected individuals, the Huntington’s BMECs weren’t as good at making new blood vessels, and the vessels they did make were leakier. So the Huntingtin mutation in these BMECs appears to be directly responsible for the faulty blood-brain barrier.

The team dug deeper into this new insight by looking for possible differences in gene activity between the healthy and Huntington’s BMECs. They found that the Wnt group of genes, which plays an important role in the development of the blood-brain barrier, are over active in the Huntington’s BMECs. This altered Wnt activity can explain the leaky defects. In fact, the use of a drug inhibitor of Wnt fixed the defects. Dr. Leslie Thompson, the team lead, described the significance of this finding in a press release:

“Now we know there are internal problems with blood vessels in the brain. This discovery can be used for possible future treatments to seal the leaky blood vessels themselves and to evaluate drug delivery to patients with HD.”

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Study leader, Leslie Thompson. Steve Zylius / UCI

A companion Cell Stem Cell report, also published this week, used the same iPSC-derived blood-brain barrier system. In that study, researchers at Cedars-Sinai pinpointed BMEC defects as the underlying cause of Allan-Herndon-Dudley syndrome, another neurologic condition that causes mental deficits and movement problems. Together these results really drive home the importance of studying the blood-brain barrier function in neurodegenerative disease.

Dr. Ryan Lim, the first author on the UC Irvine study, also points to a larger perspective on the implications of this work:

“These studies together demonstrate the incredible power of iPSCs to help us more fully understand human disease and identify the underlying causes of cellular processes that are altered.”

UCSD scientists devise tiny sensors that detect forces at cellular level

A big focus of stem cell research is trying to figure how to make a stem cell specialize, or differentiate, into a desired cell type like muscle, liver or bone. When we write about these efforts in the Stem Cellar, it’s usually in terms of researchers identifying proteins that bind to a stem cell’s surface and trigger changes in gene activity inside the cell that ultimately leads to a specific cell fate.

But, that’s not the only game in town. As incredible as it sounds, affecting a cell’s shape through mechanical forces also plays a profound role in gene activity and determining a cell’s fate. In one study, mesenchymal stem cells would specialize into fat cells or bone-forming cells depending on how much the MSCs were stretched out on a petri dish.

An artist’s illustration of nano optical fibers detecting the minuscule forces produced by swimming bacteria. Credit: Rhett S. Miller/UC Regents

Since we’re talking about individual cells, the strength of these mechanical forces is tiny, making measurements nearly impossible. But now, a research team at UC San Diego has engineered a device 100 times thinner than a human hair that can detect these miniscule forces. The study, funded in part by CIRM, was reported yesterday in Nature Photonics.

The device is made of a very thin optical fiber that’s coated with a resin which contains gold particles. The fiber is placed directly into the liquid that cells are grown in and then hit with a beam of light. The light is scattered by the gold particles and measured with a conventional light microscope. Forces and even sound waves caused by cells in the petri dish change the intensity of the light scattering which is detected by the microscope.

Donald Sirbuly,
team lead

In this study, the researchers measured astonishingly small forces (0.0000000000001 pound of force, to be exact!) in a culture of gut bacteria which swim around in the solution with the help of their whip-like flagella. The team also detected the sound of beating heart muscle cells at a level that’s a thousand times below the range of human hearing.

Dr. Donald Sirbuly, the team lead and a professor at UCSD’s Jacobs School of Engineering is excited about the research possibilities with this device:

“This work could open up new doors to track small interactions and changes that couldn’t be tracked before,” he said in a press release.

Bradley Fikes, the biotechnology reporter for the San Diego Union Tribune, reached out to others in the field to get their take on potential applications of this nanofiber device. Dr. John Marohn at Columbia University told Fikes in a news article (subscription is needed to access) that it could help stem cell scientists’ fully understand all of the intricacies of cell fate:

“So one of the cues that cells get, and they listen to these cues to decide how to change how to evolve, are just outside forces. This would give a way to kind of feel the outside forces that the cells feel, in a noninvasive way.”

And Eli Rothenberg at NYU School of Medicine, also not part of the study, summed up the device’s novelty, power and ease of use in an interview with Fikes:

“One of the main challenges in measuring things in biology is forces. We have no idea what’s going on in terms of forces in cells, in term of motion of molecules, the forces they interact with. But these sensors, you can put anywhere. They’re tiny, you can place them on the cells. If a cancer cell’s surface is moving, you can measure the forces…The fabrication of this device is quite straightforward. So, the simplicity of having this device and what you can measure with it, that’s kind of striking.”