Stories that caught our eye: Spinal cord injury trial milestone, iPS for early cancer diagnosis, and storing videos in DNA

Spinal cord injury clinical trial hits another milestone (Kevin McCormack)
We began the week with good news about our CIRM-funded clinical trial with Asterias for spinal cord injury, and so it’s nice to end the week with more good news from that same trial. On Wednesday, Asterias announced it had completed enrolling and dosing patients in their AIS-B 10 million cell group.

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People with AIS-B spinal cord injuries have some level of sensation and feeling but very little, if any, movement below the site of injury site. So for example, spinal cord injuries at the neck, would lead to very limited movement in their arms and hands. As a result, they face a challenging life and may be dependent on help in performing most daily functions, from getting out of bed to eating.astopc1

In another branch of the Asterias trial, people with even more serious AIS-A injuries – in which no feeling or movement remains below the site of spinal cord injury – experienced improvements after being treated with Asterias’ AST-OPC1 stem cell therapy. In some cases the improvements were quite dramatic. We blogged about those here.

In a news release Dr. Ed Wirth, Asterias’ Chief Medical Officer, said they hope that the five people treated in the AIS-B portion of the trial will experience similar improvements as the AIS-A group.

“Completing enrollment and dosing of the first cohort of AIS-B patients marks another important milestone for our AST-OPC1 program. We have already reported meaningful improvements in arm, hand and finger function for AIS-A patients dosed with 10 million AST-OPC1 cells and we are looking forward to reporting initial efficacy and safety data for this cohort early in 2018.”

Asterias is already treating some AIS-A patients with 20 million cells and hopes to start enrolling AIS-B patients for the 20 million cell therapy later this summer.

Earlier diagnosis of pancreatic cancer using induced pluripotent stem cells Reprogramming adult cells to an embryonic stem cell-like state is as common in research laboratories as hammers and nails are on a construction site. But a research article in this week’s edition of Science Translational Medicine used this induced pluripotent stem cell (iPSC) toolbox in a way I had never read about before. And the results of the study may lead to earlier detection of pancreatic cancer, the fourth leading cause of cancer death in the U.S.

Zaret STM pancreatic cancer tissue July 17

A pancreatic ductal adenocarcinoma
Credit: The lab of Ken Zaret, Perelman School of Medicine, University of Pennsylvania

We’ve summarized countless iPSCs studies over the years. For example, skin or blood samples from people with Parkinson’s disease can be converted to iPSCs and then specialized into brain cells to provide a means to examine the disease in a lab dish. The starting material – the skin or blood sample – typically has no connection to the disease so for all intents and purposes, it’s a healthy cell. It’s only after specializing it into a nerve cell that the disease reveals itself.

But the current study by researchers at the University of Pennsylvania used late stage pancreatic cancer cells as their iPSC cell source. One of the reasons pancreatic cancer is thought to be so deadly is because it’s usually diagnosed very late when standard treatments are less effective. So, this team aimed to reprogram the cancer cells back into an earlier stage of the cancer to hopefully find proteins or molecules that could act as early warning signals, or biomarkers, of pancreatic cancer.

Their “early-stage-cancer-in-a-dish” model strategy was a success. The team identified a protein called thrombospodin-2 (THBS2) as a new candidate biomarker. As team lead, Dr. Ken Zaret, described in a press release, measuring blood levels of THBS2 along with a late-stage cancer biomarker called CA19-9 beat out current detection tests:

“Positive results for THBS2 or CA19-9 concentrations in the blood consistently and correctly identified all stages of the cancer. Notably, THBS2 concentrations combined with CA19-9 identified early stages better than any other known method.”

DNA: the ultimate film archive device?
This last story for the week isn’t directly related to stem cells but is too cool to ignore. For the first time ever, researchers at Harvard report in Nature that they have converted a video into a DNA sequence which was then inserted into bacteria. As Gina Kolata states in her New York Times article about the research, the study represents the ultimate data archive system which can “be retrieved at will and multiplied indefinitely as the host [bacteria] divides and grows.”

A video file is nothing but a collection of “1s” and “0s” of binary code which describe the makeup of each pixel in each frame of a movie. The researchers used the genetic code within DNA to describe each pixel in a short clip of one of the world’s first motion pictures: a galloping horse captured by Eadward Muybridge in 1878.

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The resulting DNA sequence was then inserted into the chromosome of E.Coli., a common bacteria that lives in your intestines, using the CRISPR gene editing method. The video code was still retrievable after the bacteria was allowed to multiply.

The Harvard team envisions applications well beyond a mere biological hard drive. Dr. Seth Shipman, an author of the study, told Paul Rincon of BBC news that he thinks this cell system could be placed in various parts of the body to analyze cell function and “encode information about what’s going on in the cell and what’s going on in the cell environment by writing that information into their own genome”.

Perhaps then it could be used to monitor the real-time activity of stem cell therapies inside the body. For now, I’ll wait to hear about that in some upcoming science fiction film.

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.”

New stem cell technique gives brain support cells a starring role

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The Salk team. From left: Krishna Vadodaria, Lynne Moore, Carol Marchetto, Arianna Mei, Fred H. Gage, Callie Fredlender, Ruth Keithley, Ana Diniz Mendes. Photo courtesy Salk Institute

Astrocytes are some of the most common cells in the brain and central nervous system but they often get overlooked because they play a supporting role to the more glamorous neurons (even though they outnumber them around 50 to 1). But a new way of growing those astrocytes outside the brain could help pave the way for improved treatments for stroke, Alzheimer’s and other neurological problems.

Astrocytes – which get their name because of their star shape (Astron – Greek for “star” and “kyttaron” meaning cell) – have a number of key functions in the brain. They provide physical and metabolic support for neurons; they help supply energy and fuel to neurons; and they help with detoxification and injury repair, particularly in terms of reducing inflammation.

Studying these astrocytes in the lab has not been easy, however, because existing methods of producing them have been slow, cumbersome and not altogether effective at replicating their many functions.

Finding a better way

Now a team at the Salk Institute, led by CIRM-funded Professor Fred “Rusty” Gage, has developed a way of using stem cells to create astrocytes that is faster and more effective.

Their work is published in the journal Stem Cell Reports. In a news release, Gage says this is an important discovery:

“This work represents a big leap forward in our ability to model neurological disorders in a dish. Because inflammation is the common denominator in many brain disorders, better understanding astrocytes and their interactions with other cell types in the brain could provide important clues into what goes wrong in disease.”

Stylized microscopy image of an astrocyte (red) and neuron (green). (Salk Institute)

In a step by step process the Salk team used a series of chemicals, called growth factors, to help coax stem cells into becoming, first, generic brain cells, and ultimately astrocytes. These astrocytes not only behaved like the ones in our brain do, but they also have a particularly sensitive response to inflammation. This gives the team a powerful tool in helping develop new treatment to disorders of the brain.

But wait, there’s more!

As if that wasn’t enough, the researchers then used the same technique to create astrocytes from induced pluripotent stem cells (iPSCs) – adult cells, such as skin, that have been re-engineered to have the ability to turn into any other kind of cell in the body. Those man-made astrocytes also showed the same characteristics as natural ones do.

Krishna Vadodaria, one of the lead authors on the paper, says having these iPSC-created astrocytes gives them a completely new tool to help explore brain development and disease, and hopefully develop new treatments for those diseases.

“The exciting thing about using iPSCs is that if we get tissue samples from people with diseases like multiple sclerosis, Alzheimer’s or depression, we will be able to study how their astrocytes behave, and how they interact with neurons.”

Stem cell stories that caught our eye: lab-grown blood stem cells and puffer fish have the same teeth stem cells as humans

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.

Scientists finally grow blood stem cells in the lab!

Two exciting stem cell studies broke through the politics-dominated headlines this week. Both studies, published in the journal Nature, demonstrated that human hematopoietic or blood stem cells can be grown in the lab.

This news is a big deal because scientists have yet to make bonafide blood stem cells from pluripotent stem cells or other human cells. These stem cells not only create all the cells in our blood and immune systems, but also can be used to develop therapies for patients with blood cancers and genetic blood disorders.

But to do these experiments, you need a substantial source of blood stem cells – something that has eluded scientists for decades. That’s where these two studies come to the rescue. One study was spearheaded by George Daley at the Boston Children’s Hospital in Massachusetts and the other was led by Shahin Rafii at the Weill Cornell Medical College in New York City.

Researchers have made blood stem cells and progenitor cells from pluripotent stem cells. Credit: Steve Gschmeissner Getty Images

George Daley and his team developed a strategy that matured human induced pluripotent stem cells (iPS cells) into blood-forming stem and progenitor cells. It’s a two-step process that first uses a cocktail of chemicals to make hemogenic endothelium, the embryonic tissue that generates blood stem cells. The second step involved treating these intermediate cells with a combination of seven transcription factors that directed them towards a blood stem cell fate.

These modified human blood stem cells were then transplanted into mice where they developed into blood stem cells that produced blood and immune cells. First author on the study, Ryohichi Sugimura, explained the applications that their technology could be used for in a Boston Children’s Hospital news release,

“This step opens up an opportunity to take cells from patients with genetic blood disorders, use gene editing to correct their genetic defect and make functional blood cells. This also gives us the potential to have a limitless supply of blood stem cells and blood by taking cells from universal donors. This could potentially augment the blood supply for patients who need transfusions.”

The second study by Shahin Rafii and his team at Cornell used a different strategy to generate blood-forming stem cells. Instead of genetically manipulating iPS cells, they selected a more mature cell type to directly reprogram into blood stem cells. Using four transcription factors, they successfully reprogrammed mouse endothelial cells, which line the insides of blood vessels, into blood-forming stem cells that repopulated the blood and immune systems of irradiated mice.

Raffii believe his method is simpler and more efficient than Daley’s. In coverage by Nature News, he commented,

“Using the most efficient method to generate stem cells matters because every time a gene is added to a batch of cells, a large portion of the batch fails to incorporate it and must be thrown out. There is also a risk that some cells will mutate after they are modified in the lab, and could form tumors if they are implanted into people.”

To play devil’s advocate, Daley’s technique might appeal more to some because the starting source of iPS cells is much easier to obtain and culture in the lab than endothelial cells that have to be extracted from the blood vessels of animals or people. Furthermore, Daley argued that his team’s method could “be made more efficient, and [is] less likely to spur tumor growth and other abnormalities in modified cells.”

The Nature News article compares the achievements of both studies and concluded,

“Time will determine which approach succeeds. But the latest advances have buoyed the spirits of researchers who have been frustrated by their inability to generate blood stem cells from iPS cells.”

 

Humans and puffer fish have the same tooth-making stem cells.

Here’s a fun fact for your next blind date: humans and puffer fish share the same genes that are responsible for making teeth. Scientists from the University of Sheffield in England discovered that the stem cells that make teeth in puffer fish are the same stem cells that make the pearly whites in humans. Their work was published in the journal PNAS earlier this week.

Puffer fish. Photo by pingpogz on Flickr.

But if you look at this puffer fish, you’ll see a dramatic difference between its smile and ours – their teeth look more like a beak. Research has shown that the tooth-forming stem cells in puffer fish produce tooth plates that form a beak-like structure, which helps them crush and consume their prey.

So why is this shared evolution between humans and puffer fish important when our teeth look and function so differently? The scientists behind this research believe that studying the pufferfish could unearth answers about tooth loss in humans. The lead author on the study, Dr. Gareth Fraser, concluded in coverage by Phys.org,

“Our study questioned how pufferfish make a beak and now we’ve discovered the stem cells responsible and the genes that govern this process of continuous regeneration. These are also involved in general vertebrate tooth regeneration, including in humans. The fact that all vertebrates regenerate their teeth in the same way with a set of conserved stem cells means that we can use these studies in more obscure fishes to provide clues to how we can address questions of tooth loss in humans.”

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.”

Stem cell stories that caught our eye: update on Capricor’s heart attack trial; lithium on the brain; and how stem cells do math

Capricor ALLSTARToday our partners Capricor Therapeutics announced that its stem cell therapy for patients who have experienced a large heart attack is unlikely to meet one of its key goals, namely reducing the scar size in the heart 12 months after treatment.

The news came after analyzing results from patients at the halfway point of the trial, six months after their treatment in the Phase 2 ALLSTAR clinical trial which CIRM was funding. They found that there was no significant difference in the reduction in scarring on the heart for patients treated with donor heart-derived stem cells, compared to patients given a placebo.

Obviously this is disappointing news for everyone involved, but we know that not all clinical trials are going to be successful. CIRM supported this research because it clearly addressed an unmet medical need and because an earlier Phase 1 study had showed promise in helping prevent decline in heart function after a heart attack.

Yet even with this failure to repeat that promise in this trial,  we learned valuable lessons.

In a news release, Dr. Tim Henry, Director of the Division of Interventional Technologies in the Heart Institute at Cedars-Sinai Medical Center and a Co-Principal Investigator on the trial said:

“We are encouraged to see reductions in left ventricular volume measures in the CAP-1002 treated patients, an important indicator of reverse remodeling of the heart. These findings support the biological activity of CAP-1002.”

Capricor still has a clinical trial using CAP-1002 to treat boys and young men developing heart failure due to Duchenne Muscular Dystrophy (DMD).

Lithium gives up its mood stabilizing secrets

As far back as the late 1800s, doctors have recognized that lithium can help people with mood disorders. For decades, this inexpensive drug has been an effective first line of treatment for bipolar disorder, a condition that causes extreme mood swings. And yet, scientists have never had a good handle on how it works. That is, until this week.

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Evan Snyder

Reporting in the Proceedings of the National Academy of Sciences (PNAS), a research team at Sanford Burnham Prebys Medical Discovery Institute have identified the molecular basis of the lithium’s benefit to bipolar patients.  Team lead Dr. Evan Snyder explained in a press release why his group’s discovery is so important for patients:

“Lithium has been used to treat bipolar disorder for generations, but up until now our lack of knowledge about why the therapy does or does not work for a particular patient led to unnecessary dosing and delayed finding an effective treatment. Further, its side effects are intolerable for many patients, limiting its use and creating an urgent need for more targeted drugs with minimal risks.”

The study, funded in part by CIRM, attempted to understand lithium’s beneficial effects by comparing cells from patient who respond to those who don’t (only about a third of patients are responders). Induced pluripotent stem cells (iPSCs) were generated from both groups of patients and then the cells were specialized into nerve cells that play a role in bipolar disorder. The team took an unbiased approach by looking for differences in proteins between the two sets of cells.

The team zeroed in on a protein called CRMP2 that was much less functional in the cells from the lithium-responsive patients. When lithium was added to these cells the disruption in CRMP2’s activity was fixed. Now that the team has identified the molecular location of lithium’s effects, they can now search for new drugs that do the same thing more effectively and with fewer side effects.

The stem cell: a biological calculator?

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Can stem cells do math?

Stem cells are pretty amazing critters but can they do math? The answer appears to be yes according to a fascinating study published this week in PNAS Proceedings of the National Academy of Sciences.

Stem cells, like all cells, process information from the outside through different receptors that stick out from the cells’ outer membranes like a satellite TV dish. Protein growth factors bind those receptors which trigger a domino effect of protein activity inside the cell, called cell signaling, that transfers the initial receptor signal from one protein to another. Ultimately that cascade leads to the accumulation of specific proteins in the nucleus where they either turn on or off specific genes.

Intuition would tell you that the amount of gene activity in response to the cell signaling should correspond to the amount of protein that gets into the nucleus. And that’s been the prevailing view of scientists. But the current study by a Caltech research team debunks this idea. Using real-time video microscopy filming, the team captured cell signaling in individual cells; in this case they used an immature muscle cell called a myoblast.

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Behavior of cells over time after they have received a Tgf-beta signal. The brightness of the nuclei (circled in red) indicates how much Smad protein is present. This brightness varies from cell to cell, but the ratio of brightness after the signal to before the signal is about the same. Image: Goentoro lab, CalTech.

To their surprise the same amount of growth factor given to different myoblasts cells led to the accumulation of very different amounts of a protein called Smad3 in the cells’ nuclei, as much as a 40-fold difference across the cells. But after some number crunching, they discovered that dividing the amount of Smad3 after growth factor stimulation by the Smad3 amount before growth stimulation was similar in all the cells.

As team lead Dr. Lea Goentoro mentions in a press release, this result has some very important implications for studying human disease:

“Prior to this work, researchers trying to characterize the properties of a tumor might take a slice from it and measure the total amount of Smad in cells. Our results show that to understand these cells one must instead measure the change in Smad over time.”

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.

BodyChlamydia

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.”