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.

BloodBrainBarrier

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.”

 

 

Pleasant surprise reveals molecular insights about graying and balding hair

A lesson that every lab researcher learns early in their career is that experiments often don’t give you the results you expect. But that’s not always a bad thing. Sometimes surprising results can lead to new insights or can even steer your research in completely new, exciting directions.

That’s what happened to scientists at the University of Texas Southwestern Medical Center. What started out as a project to better understand a genetic disorder – called neurofibromatosis – that causes benign tumor growth on nerve cells, turned into new discoveries about the cellular basis for graying and balding hair – at least in mice.

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Starting at 30 days after birth (P30, upper right picture), mouse lacking the SCF gene (top mouse in each picture) gradually loses hair pigment while hair color of control mouse remains unchanged. Photo: Fig 1A, Genes Dev. 2017 May 2.

The team was studying neurofibromatosis in mouse cells that produce Krox20, a protein which plays a role in the development of nerve cells. Krox20, in turn, stimulates the production of another protein called Stem Cell Factor (SCF). With some genetic engineering tricks, a mouse strain lacking SCF specifically in these Krox20-producing cells was bred to uncover SCF’s impact on neurofibromatosis.

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Hair production and pigmentation occurs in hair follicle. Image: Shutterstock

But the researchers couldn’t help noticing something else: as reported in Genes and Development, just a month after birth, all 20 mice had graying fur and by nine months, their fur was completely white. Another set of mice was bred to lack Krox20-producing cells. The resulting animals completely lacked hair. Further experiments determined that the Krox20-producing cells in the hair follicle were stem cell-like progenitor cells that give rise to the cells responsible for hair production and pigmentation.

Piecing the data together, the researchers created a visual model of the hair follicle in which the progenitor cells maintain a steady supply of hair-producing cells with Krox20 playing a critical role. And the SCF produced by those cells allows the uptake of hair pigment called melanin, from nearby melanocyte cells also found in the hair follicle.

This model suggests that as we age, something causes a reduction in SCF in the hair follicle which leads to graying hair. The model also suggests that thinning hair, which is quite common in both men and women, is triggered by a reduction in the number of progenitor cells in the follicle.

Given that the treatment of hair loss and graying are multi-billion dollar industries, it’s no surprise that this story got a lot of attention in the press. Based on the titles of some of those news articles, you’d think new, game-changing hair products are just around the corner. In reality, this research is at a very early stage and will require many years of follow up experiments to figure out if and how commercialization of the technology is possible.

Still, as lead scientist Dr. Lu Le explains in a press release, the team has a vision for what their ultimate goal might look like:

“With this knowledge, we hope in the future to create a topical compound or to safely deliver the necessary gene to hair follicles to correct these cosmetic problems.”

 

Stem cell stories that caught our eye: better ovarian cancer drugs, creating inner ear tissue, small fish big splash

Two drugs are better than one for ovarian cancer (Karen Ring). Earlier this week, scientists from UCLA reported that a combination drug therapy could be an effective treatment for 50% of aggressive ovarian cancers. The study was published in the journal Precision Oncology and was led by Dr. Sanaz Memarzadeh.

Women with high-grade ovarian tumors have an 85% chance of tumor recurrence after treatment with a common chemotherapy drug called carboplatin. The UCLA team found in a previous study that ovarian cancer stem cells are to blame because they are resistant to carboplatin. It’s because these stem cells have an abundance of proteins called cIAPs, which prevent cell death from chemotherapy.

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Ovarian cancer cells (blue) expressing cIAP protein (red) on the left are more sensitive to a combination therapy than cancer cells that don’t express the protein on the right. (UCLA Broad Stem Cell Research Center/Precision Oncology)

Memarzadeh discovered that an experimental drug called birinapant made some ovarian cancer tumors more sensitive to chemotherapy treatment by breaking down cIAPs. This gave her the idea that combining the two drugs, birinapant and carboplatin, might be a more effective strategy for treating aggressive ovarian tumors.

By treating with the two drugs simultaneously, the scientists improved the survival rate of mice with ovarian cancer. They also tested this combo drug treatment on 23 ovarian cancer cell lines derived from women with highly aggressive tumors. The treatment killed off half of the cell lines indicating that some forms of this cancer are resistant to the combination treatment.

When they measured the levels of cIAPs in the human ovarian cancer cell lines, they found that high levels of the proteins were associated with ovarian tumor cells that responded well to the combination treatment. This is exciting because it means that clinicians can analyze tumor biopsies for cIAP levels to determine whether certain ovarian tumors would respond well to combination therapy.

Memarzadeh shared her plans for future research in a UCLA news release,

“I believe that our research potentially points to a new treatment option. In the near future, I hope to initiate a phase 1/2 clinical trial for women with ovarian cancer tumors predicted to benefit from this combination therapy.”

In a first, researchers create inner ear tissue. From heart muscle to brain cells to insulin-producing cells, researchers have figured out how to make a long list of different human cell types using induced pluripotent stem cells (iPSCs) – cells taken from the body and reprogrammed into a stem cell-like state.

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Human inner ear organoid with sensory hair cells (cyan) and sensory neurons (yellow). An antibody for the protein CTBP2 reveals cell nuclei as well as synapses between hair cells and neurons (magenta). | Photo: Karl Koehler

This week, a research group at the Indiana University School of Medicine successfully added inner ear cells to that list. This feat, published in Nature Biotechnology, is especially important given the fact that the inner ear is one of the few parts of the body that cannot be biopsied for further examination. With these cells in hands, new insights into the causes of hearing loss and balance disorders may be on the horizon.

The inner ear contains 75,000 sensory hair cells that convert sound waves into electrical signals to the brain. Loud noises, drug toxicity, and genetic mutations can permanently damage the hair cells leading to hearing loss and dizziness. Over 15%  of the U.S. population have some form of hearing loss and that number swells to 67% for people over 75.

Due to the complex shape of the inner ear, the team grew the iPSCs into three dimensional balls of cells rather than growing them as a flat layer of cells on a petri dish. With educated guesses sprinkled in with some trial and error, the scientists, for the time, identified a recipe of proteins that stimulated the iPSCs to transform into inner ear tissue. And like any great recipe, it wasn’t so much the ingredient list but the timing that was key:

“If you apply these signals at the wrong time you can potentially generate a brain instead of an inner ear,” first author Dr. Karl Koehler said in an interview with Gizmodo. “The real breakthrough is that we figured out the exact timing to do each one of these [protein] treatments.”

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Senior author, Eri Hashino, Ph.D., and first author, Karl R. Koehler, Ph.D. Photo: Indiana University

Careful examination shows that the tissue, referred to as organoids, not only contained the sensory hair cells of the inner ear cell but also nerve cells, or neurons, that are responsible for relaying the sound waves to the brain. Koehler explained the importance of this result in a press release:

“We also found neurons, like those that transmit signals from the ear to the brain, forming connections with sensory cells. This is an exciting feature of these organoids because both cell types are critical for proper hearing and balance.”

Though it’s still early days, these iPSC-derived inner ear organoids are a key step toward the ultimate goal of repairing hearing loss. Senior author, Dr. Eri Hashino, talked about the team’s approach to reach that goal:

“Up until now, potential drugs or therapies have been tested on animal cells, which often behave differently from human cells. We hope to discover new drugs capable of helping regenerate the sound-sending hair cells in the inner ear of those who have severe hearing problems.”

This man’s research is no fish tale
And finally, we leave you this week with a cool article and video by STAT. It features Dr. Leonard Zon of Harvard University and his many, many tanks full of zebrafish. This little fish has made a huge splash in understanding human development and disease. But don’t take my word for it, watch the video!

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Stem cell stories that caught our eye: spinal cord injury trial keeps pace; SMART cells make cartilage and drugs

CIRM-funded spinal cord injury trial keeping a steady pace

Taking an idea for a stem cell treatment and developing it into a Food and Drug Administration-approved cell therapy is like running the Boston Marathon because it requires incremental progress rather than a quick sprint. Asterias Biotherapeutics continues to keep a steady pace and to hit the proper milestones in its race to develop a stem cell-based treatment for acute spinal cord injury.


Just this week in fact, the company announced an important safety milestone for its CIRM-funded SciStar clinical trial. This trial is testing the safety and effectiveness of AST-OPC1, a human embryonic stem cell-derived cell therapy that aims to regenerate some of the lost movement and feeling resulting from spinal cord injuries to the neck.

Periodically, an independent safety review board called the Data Monitoring Committee (DMC) reviews the clinical trial data to make sure the treatment is safe in patients. That’s exactly what the DMC concluded as its latest review. They recommended that treatments with 10 and 20 million cell doses should continue as planned with newly enrolled clinical trial participants.

About a month ago, Asterias reported that six of the six participants who had received a 10 million cell dose – which is transplanted directly into the spinal cord at the site of injury – have shown improvement in arm, hand and finger function nine months after the treatment. These outcomes are better than what would be expected by spontaneous recovery often observed in patients without stem cell treatment. So, 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 the 20 million cell dose.

It’s a two-fer: SMART cells that make cartilage and release anti-inflammation drug
“It’s a floor wax!”….“No, it’s a dessert topping!”
“Hey, hey calm down you two. New Shimmer is a floor wax and a dessert topping!”

Those are a few lines from the classic Saturday Night Live skit that I was reminded of when reading about research published yesterday in Stem Cell Reports. The clever study generated stem cells that not only specialize into cartilage tissue that could help repair arthritic joints but the cells also act as a drug dispenser that triggers the release of a protein that dampens inflammation.

Using CRISPR technology, a team of researchers led by Farshid Guilak, PhD, at Washington University School of Medicine in St. Louis, rewired stem cells’ genetic circuits to produce an anti-inflammatory arthritis drug when the cells encounter inflammation. The technique eventually could act as a vaccine for arthritis and other chronic conditions. Image: ELLA MARUSHCHENKO

The cells were devised by a research team at Washington University School of Medicine in St. Louis. They started out with skin cells collected from the tails of mice. Using the induced pluripotent stem cell technique, the skin cells were reprogrammed into an embryonic stem cell-like state. Then came the ingenious steps. The team used the CRISPR gene-editing method to create a negative feedback loop in the cells’ inflammation response. They removed a gene that is activated by the potent inflammatory protein, TNF-alpha and replaced it with a gene that blocks TNF-alpha. Analogous experiments were carried out with another protein called IL-1.

Rheumatoid arthritis often affects the small joints causing painful swelling and disfigurement. Image: Wikipedia

Now, TNF-alpha plays a key role in triggering inflammation in arthritic joints. But this engineered cell, in the presence of TNF-alpha, activates the production of a protein that inhibits the actions of TNF-alpha. Then the team converted these stem cells into cartilage tissue and they went on to show that the cartilage was indeed resistant to inflammation. Pretty smart, huh? In fact, the researchers called them SMART cells for “Stem cells Modified for Autonomous Regenerative Therapy.” First author Dr. Jonathan Brunger summed up the approach succinctly in a press release:

“We hijacked an inflammatory pathway to create cells that produced a protective drug.”

This type of targeted treatment of arthritis would have a huge advantage over current anti-TNF-alpha therapies. Arthritis drugs like Enbrel, Humira and Remicade are very effective but they block the immune response throughout the body which carries an increased risk for serious infections and even cancer.

The team is now testing the cells in animal models of rheumatoid arthritis as well as other inflammation disorders. Those results will be important to determine whether or not this approach can work in a living animal. But senior Dr. Farshid Guilak also has an eye on future applications of SMART cells:

“We believe this strategy also may work for other systems that depend on a feedback loop. In diabetes, for example, it’s possible we could make stem cells that would sense glucose and turn on insulin in response. We are using pluripotent stem cells, so we can make them into any cell type, and with CRISPR, we can remove or insert genes that have the potential to treat many types of disorders.”

Knocking out sexually transmitted disease with stem cells and CRISPR gene editing

When used in tandem, stem cells and gene editing make a powerful pair in the development of cell therapies for genetic diseases like sickle cell anemia and bubble baby disease. But the applications of these cutting-edge technologies go well beyond cell therapies.

This week, researchers at the Wellcome Trust Sanger Institute in the UK and the University of British Columbia (UBC) in Canada, report their use of induced pluripotent stem cells (iPSCs) and the CRISPR gene editing to better understand chlamydia, a very common sexually transmitted disease. And in the process, the researchers gained insights for developing new drug treatments.

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Human macrophage, a type of white blood cell, interacting with a Chlamydia trachomatis bacteria cell. Image: Sanger Institute / Genome Research Limited

Chlamydia is caused by infection with the bacteria Chlamydia trachomatis. According to the Centers for Disease Control (CDC), there were over 1.5 million cases of Chlamydia reported in the U.S. in 2015. And there are thought to be almost 3 million new cases each year. Men with Chlamydia usually do not face many health issues. Women, on the other hand, can suffer serious health complications like pelvic inflammatory disease and infertility.

Although it’s easily treatable with antibiotics, the disease often goes unnoticed because infected people may not show symptoms. And because of the rising fear of antibiotic-resistant bacteria, there’s a need to develop new types of drugs to treat Chlamydia.

To tackle this challenge, the research teams focused first on better understanding how the bacteria infects the human immune system. As first author Dr. Amy Yeung from the Wellcome Trust Sanger Institute explained in a press release, researchers knew they were up against difficult to treat foe:

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Amy Yeung

“Chlamydia is tricky to study because it can permeate and hide in macrophages [a type of white blood cell] where it is difficult to reach with antibiotics. Inside the macrophage, one or two chlamydia cells can replicate into hundreds in just a day or two, before bursting out to spread the infection.”

In the study, published in Nature Communications, the teams chose to examine human macrophages derived from iPSCs. This decision had a few advantages over previous studies.  Most Chlamydia studies up until this point had either used macrophages from mice, which don’t always accurately reflect what’s going on in the human immune system, or human macrophage cell lines, which have genetic abnormalities that allow them to divide indefinitely.

With these human iPSC-derived macrophages, the team then used CRISPR gene editing technology to systematically delete, or “knockout”, genes that may play a role in Chlamydia infection. Lead author Dr. Robert Hancock from UBC described the power of this approach:

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Robert Hancock

“We can knock out specific genes in stem cells and look at how the gene editing influences the resulting macrophages and their interaction with chlamydia. We’re effectively sieving through the genome to find key players and can now easily see genes that weren’t previously thought to be involved in fighting the infection.”

In fact, they found two genes that appear to play an important role in Chlamydia infection. When they knocked out either the IRF5 or IL-10RA gene, the macrophages were much more vulnerable to infection. The team is now eager to examine these two genes as possible targets for novel Chlamyia drug treatments. But as Dr. Gordon Dougan –the senior author from the Sanger Institute – explains, these studies could be far-reaching:

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Gordon Dougan

“This system can be extended to study other pathogens and advance our understanding of the interactions between human hosts and infections. We are starting to unravel the role our genetics play in battling infections, such as chlamydia, and these results could go towards designing more effective treatments in the future.”

Could revving up stem cells help senior citizens heal as fast as high school seniors?

All physicians, especially surgeons, sport medicine doctors, and military medical corps share a similar wish: to able to speed up the healing process for their patients’ incisions and injuries. Data published this week in Cell Reports may one day fulfill that wish. The study – reported by a Stanford University research team – pinpoints a single protein that revs up stem cells in the body, enabling them to repair tissue at a quicker rate.

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Muscle fibers (dark areas surrounding by green circles) are larger in mice injected with HGFA protein (right panel) compared to untreated mice (left panel), an indication of faster healing after muscle injury.
(Image: Cell Reports 19 (3) p. 479-486, fig 3C)

Most of the time, adult stem cells in the body keep to themselves and rarely divide. This calmness helps preserve this important, small pool of cells and avoids unnecessary mutations that may happen whenever DNA is copied during cell division.

To respond to injury, stem cells must be primed by dividing one time, which is a very slow process and can take several days. Once in this “alert” state, the stem cells are poised to start dividing much faster and help repair damaged tissue. The Stanford team, led by Dr. Thomas Rando, aimed to track down the signals that are responsible for this priming process with the hope of developing drugs that could help jump-start the healing process.

Super healing serum: it’s not just in video games
The team collected blood serum from mice two days after the animals had been subjected to a muscle injury (the mice were placed under anesthesia during the procedure and given pain medication afterwards). When that “injured” blood was injected into a different set of mice, their muscle stem cells became primed much faster than mice injected with “uninjured” blood.

“Clearly, blood from the injured animal contains a factor that alerts the stem cells,” said Rando in a press release. “We wanted to know, what is it in the blood that is doing this?”

 

A deeper examination of the priming process zeroed in on a muscle stem cell signal that is turned on by a protein in the blood called hepatocyte growth factor (HGF). So, it seemed likely that HGF was the protein that they had been looking for. But, to their surprise, there were no differences in the amount of HGF found in blood from injured and uninjured mice.

HGFA: the holy grail of healing?
It turns out, though, that HGF must first be chopped in two by an enzyme called HGFA to become active. When the team went back and examined the injured and uninjured blood, they found that it was HGFA which showed a difference: it was more active in the injured blood.

To show that HGFA was directly involved in stimulating tissue repair, the team injected mice with the enzyme two days before the muscle injury procedure. Twenty days post injury, the mice injected with HGFA had regenerated larger muscle fibers compared to untreated mice. Even more telling, nine days after the HGFA treatment, the mice had better recovery in terms of their wheel running activity compared to untreated mice.

To mimic tissue repair after a surgery incision, the team also looked at the impact of HGFA on skin wound healing. Like the muscle injury results, injecting animals with HGFA two days before creating a skin injury led to better wound healing compared to untreated mice. Even the hair that had been shaved at the surgical site grew back faster. First author Dr. Joseph Rodgers, now at USC, summed up the clinical implications of these results :

“Our research shows that by priming the body before an injury you can speed the process of tissue repair and recovery, similar to how a vaccine prepares the body to fight infection. We believe this could be a therapeutic approach to improve recovery in situations where injuries can be anticipated, such as surgery, combat or sports.”

Could we help senior citizens heal as fast as high school seniors?
Another application for this therapeutic approach may be for the elderly. Lots of things slow down when you get older including your body’s ability to heal itself. This observation sparks an intriguing question for Rando:

“Stem cell activity diminishes with advancing age, and older people heal more slowly and less effectively than younger people. Might it be possible to restore youthful healing by activating this [HGFA] pathway? We’d love to find out.”

I bet a lot of people would love for you to find out, too.

A life-threatening childhood disease and the CIRM-funded team seeking a stem cell cure featured in new video

“My hope for Brooke is she can one day look back and we have to remind her of the disease she once had.”

That’s Clay Emerson’s biggest hope for his young daughter Brooke, who has cystinosis, a life-threatening genetic disease that appears by the age of two and over time causes damage to many organs, especially the kidneys and eyes but also the liver, muscle, brain, pancreas and other tissues. The Emersons and other families affected by the disease are featured in a recent video produced by the Cystinosis Research Foundation.

I doubt many can watch the seven-minute piece without getting a lump in their throat or watery eyes. One of many heart wrenching scene shows Brooke’s mother, Jill Emerson, preparing a day’s worth of medicine that she administers through a tube connected to Brook’s stomach.

“Brooke takes about 20 doses of medication a day and that’s throughout the 24hr period in a day. The poor kid hasn’t had a full night’s sleep ever in her entire life because I have to wake her up to take her life-saving medicine.”

Jill Emerson prepares a day’s worth of medicine for her daughter Brooke. Unfortunately, the treatments only slow the progression of cystinosis but don’t cure it. (Video Still: Cystinosis Research Foundation)

But these treatments only slow down the progression of this incurable disease. Even perfect compliance with taking the medicine doesn’t stop severe complications of the disease including kidney failure, diabetes, muscle weakness, and difficulty swallowing just to name a few. Cystinosis also shorten life spans. Natalie, the video’s narrator, a young woman with cystinosis wonders how much time she has left:

“There are people in their 20s who have recently died from cystinosis. I am 25 years old and I often think about how long I have to live. I’m praying for a cure for all of us.”

Her prayers may be answered in the form of a stem cell gene therapy treatment. UCSD researcher Dr. Stephanie Cherqui, who is also featured in the video, received $5 million in CIRM funding to bring her team’s therapy to clinical trials in people.

At a cellular level, cystinosis is caused by mutations in a gene called CTNS which lead to an accumulation of the amino acid cysteine. The excess cysteine eventually forms crystals causing devastating damage to cells throughout the body. Cherqui’s treatment strategy is to take blood stem cells from affected individuals, insert a good copy of the CTNS gene using genome editing into the cells’ DNA, and then transplant the cells back into the patient.

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Dr. Stephanie Cherqui and her team are working hard to bring a stem cell gene therapy treatment for cystinosis to clinical trials. (Video Still: Cystinosis Research Foundation)

Her team has preliminary evidence that the strategy works in mice. Now, they will use the CIRM grant to complete these pre-clinical studies and prepare the genetically engineered blood stem cells for use in patients. These steps are necessary to get the green light from the Food and Drug Administration (FDA) to begin clinical trials, hopefully some time this year.

Cherqui says that if all goes well, the treatment approach may have benefits beyond cystinosis:

“If we can bring this to the finish line, we can then show the way to maybe hundreds, maybe thousands of other genetic diseases. So this could be a real benefit to mankind.”

Fantastic Voyage: using stem cells to build live 3D maps of our cells

From the 1966 sci-fi action thriller Fantastic Voyage to the recent, hilarious cartoon, Phineas and Ferb, TV and film have often depicted the idea of people miniaturizing themselves and traveling into the microscopic world of the human body. Now, that journey is a reality for you and me.

Well, sort of.

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Traveling inside the human body is a popular story plot.

This week, the Allen Institute for Cell Science launched the Allen Cell Explorer, an online portal to some very cool 3D (and equally cool 2D) microscopic images and movies of human induced pluripotent stem cells (iPSCs)-derived cells which users can manipulate. Seattle Times science reporter Sandi Doughton explains further in her April 5th article:

“Users can rotate the images on their computer screens and zoom in on structures tagged with glowing, fluorescent dyes. Time-lapse movies on the site show how cells interact and change over time.”

The project was made possible by a $100 million grant by Paul Allen, who co-founded Microsoft along with Bill Gates. With that kind of money, the website is not just for “ooo-ing” and “ahhh-ing” at the beautiful microscopy. It also has ambitious scientific research goals such as using the cell imagery for building predictive computer models of cell behavior. Watch this excellent introduction video produced by the institute:

With iPSCs as their source material, researchers will have the ability to examine nearly any cell type of their choosing with the Allen Cell Explorer. University of Washington biologist Benjamin Freedman, who uses iPS cells to study kidney disease, spoke to Doughton about the importance of this large-scale effort to map out the inner workings of cell.

“We need to understand what’s happening in these diseases at the cellular level and how that affects the tissue if we’re ever going to be able to treat the root cause of the disease and not just the symptoms.”

You can visit the portal at: http://www.allencell.org/. Though it’s pretty technical now, the creators plan to add educational tools in the future to make it more user friendly for students and the general public.