Headline: Stem Cell Roundup: Here are some stem cell stories that caught our eye this past week.

In search of a miracle

Jordan and mother

Luane Beck holds Jordan in the emergency room while he suffers a prolonged seizure. Jordan’s seizures sometimes occur one after another with no break, and they can be deadly without emergency care. Photo courtesy San Francisco Chronicle’s Kim Clark

One of the toughest parts of my job is getting daily calls and emails from people desperate for a stem cell treatment or cure for themselves or a loved one and having to tell them that I don’t know of any. You can hear in their voice, read it in their emails, how hard it is for them to see someone they love in pain or distress and not be able to help them.

I know that many of those people may think about turning to one of the many stem cell clinics, here in the US and in Mexico and other countries, that are offering unproven and unapproved therapies. These clinics are offering desperate people a sense of hope, even if there is no evidence that the therapies they provide are either safe or effective.

And these “therapies” come with a big cost, both emotional and financial.

The San Francisco Chronicle this week launched the first in a series of stories they are doing about stem cells and stem cell research, the progress being made and the problems the field still faces.

One of the biggest problems, are clinics that offer hope, at a steep price, but no evidence to show that hope is justified. The first piece in the Chronicle series is a powerful, heart breaking story of one mother’s love for her son and her determination to do all she can to help him, and the difficult, almost impossible choices she has to make along the way.

It’s called: In search of a miracle.

A little turbulence, and a French press-like device, can help boost blood platelet production

Every year more than 21 million units of blood are transfused into people in the US. It’s a simple, life-saving procedure. One of the most important elements in transfusions are  platelets, the cells that stop bleeding and have other healing properties. Platelets, however, have a very short shelf life and so there is a constant need to get more from donors. Now a new study from Japan may help fix that problem.

Platelets are small cells that break off much larger cells called megakaryocytes. Scientists at the Center for iPS Cell Research and Application (CiRA) created billions of megakaryocytes using iPS technology (which turns ordinary cells into any other kind of cell in the body) and then placed them in a bioreactor. The bioreactor then pushed the cells up and down – much like you push down on a French press coffee maker – which helped promote the generation of platelets.

In their study, published in the journal Cell, they report they were able to generate 100 billion platelets, enough to be able to treat patients.

In a news release, CiRA Professor Koji Eto said they have shown this works in mice and now they want to see if it also works in people:

“Our goal is to produce platelets in the lab to replace human donors.”

Stem Cell Photo of the Week 

Photo Jul 11, 6 00 19 PM

Students at the CIRM Bridges program practice their “elevator pitch”. Photo Kyle Chesser

This week we held our annual CIRM Bridges to Stem Cell Research conference in Newport Beach. The Bridges program provides paid internships for undergraduate and masters-level students, a chance to work in a world-class stem cell research facility and get the experience needed to pursue a career in science. The program is training the next generation of stem cell scientists to fill jobs in California’s growing stem cell research sector.

This year we got the students to practice an “elevator Pitch”, a 30 second explanation, in plain English, of what they do, why they do it and why people should care. It’s a fun exercise but also an important one. We want scientists to be able to explain to the public what they are doing and why it’s important. After all, the people of California are supporting this work so they have a right to know, in language they can understand, how their money is changing the face of medicine.

For the first time, scientists entirely reprogram human skin cells to iPSCs using CRISPR

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CRISPR iPSC colony of human skin cells showing expression of SOX2 and TRA-1-60, markers of human embryonic pluripotent stem cells

Back in 2012, Shinya Yamanaka was awarded the Nobel Prize in Physiology or Medicine for his group’s identification of “Yamanaka Factors,” a group of genes that are capable of turning ordinary skin cells into induced pluripotentent stem cells (iPSCs) which have the ability to become any type of cell within the body. Discovery of iPSCs was, and has been, groundbreaking because it not only allows for unprecedented avenues to study human disease, but also has implications for using a patient’s own cells to treat a wide variety of diseases.

Recently, Timo Otonkoski’s group at the University of Helsinki along with Juha Kere’s group at the Karolinska Institutet and King’s College, London have found a way to program iPSCs from skin cells using CRISPR, a gene editing technology. Their approach allows for the induction, or turning on of iPSCs using the cells own DNA, instead of introducing the previously identified Yamanka Factors into cells of interest.

As detailed in their study, published in the journal Nature Communications, this is the first instance of mature human cells being completely reprogrammed into pluripotent cells using only CRISPR. Instead of using the canonical CRISPR system that allows the CAS9 protein (an enzyme that is able to cut DNA, thus rendering a gene of interest dysfunctional) to mutate any gene of interest, this group used a modified version of the CAS9 protein, which allows them to turn on or off the gene that CAS9 is targeted to.

The robustness of their approach lies in the researcher’s identification of a DNA sequence that is commonly found near genes involved in embryonic development. As CAS9 needs to be guided to genes of interest to do its job, identification of this common motif allows multiple genes associated with pluripotency to be activated in mature human skin cells, and greatly increased the efficiency and effectiveness of this approach.

In a press release, Dr. Otonkoski further highlights the novelty and viability of this approach:

“…Reprogramming based on activation of endogenous genes rather than overexpression of transgenes is…theoretically a more physiological way of controlling cell fate and may result in more normal cells…”

 

Friday Stem Cell Roundup: Making Nerves from Blood; New Clues to Treating Parkinson’s

Stanford lab develops method to make nerve cells from blood.

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Induced neuronal (iN) cells derived from adult human blood cells. Credit: Marius Wernig, Stanford University.

Back in 2010, Stanford Professor Marius Wernig and his team devised a method to directly convert skin cells into neurons, a nerve cell. This so-called transdifferentiation technique leapfrogs over the need to first reprogram the skin cells into induced pluripotent stem cells. This breakthrough provided a more efficient path to studying how genetics plays a role in various mental disorders, like autism or schizophrenia, using patient-derived cells. But these types of genetic analyses require data from many patients and obtaining patient skin samples hampered progress because it’s not only an invasive, somewhat painful procedure but it also takes time and money to prepare the tissue sample for the transdifferentiation method.

This week, the Wernig lab reported on a solution to this bottleneck in the journal, PNAS. The study, funded in part by CIRM, describes a variation on their transdifferentiation method which converts T cells from the immune system, instead of skin cells, into neurons. The huge advantage with T cells is that they can be isolated from readily available blood samples, both fresh or frozen. In a press release, Wernig explains this unexpected but very welcomed result:

“It’s kind of shocking how simple it is to convert T cells into functional neurons in just a few days. T cells are very specialized immune cells with a simple round shape, so the rapid transformation is somewhat mind-boggling. We now have a way to directly study the neuronal function of, in principle, hundreds of people with schizophrenia and autism. For decades we’ve had very few clues about the origins of these disorders or how to treat them. Now we can start to answer so many questions.”

Two studies targeting Parkinson’s offer new clues to treating the disease (Kevin McCormack)
Despite decades of study, Parkinson’s disease remains something of a mystery. We know many of the symptoms – trembling hands and legs, stiff muscles – are triggered by the loss of dopamine producing cells in the brain, but we are not sure what causes those cells to die. Despite that lack of certainty researchers in Germany may have found a way to treat the disease.

Mitochondria

Simple diagram of a mitochondria.

They took skin cells from people with Parkinson’s and turned them into the kinds of nerve cell destroyed by the disease. They found the cells had defective mitochondria, which help produce energy for the cells. Then they added a form of vitamin B3, called nicotinamide, which helped create new, healthy mitochondria.

In an article in Science & Technology Research News Dr. Michela Deleidi, the lead researcher on the team, said this could offer new pathways to treat Parkinson’s:

“This substance stimulates the faulty energy metabolism in the affected nerve cells and protects them from dying off. Our results suggest that the loss of mitochondria does indeed play a significant role in the genesis of Parkinson’s disease. Administering nicotinamide riboside may be a new starting-point for treatment.”

The study is published in the journal Cell Reports.

While movement disorders are a well-recognized feature of Parkinson’s another problem people with the condition suffer is sleep disturbances. Many people with Parkinson’s have trouble falling asleep or remaining asleep resulting in insomnia and daytime sleepiness. Now researchers in Belgium may have uncovered the cause.

Working with fruit flies that had been genetically modified to have Parkinson’s symptoms, the researchers discovered problems with neuropeptidergic neurons, the type of brain cell that helps regulate sleep patterns. Those cells seemed to lack a lipid, a fat-like substance, called phosphatidylserine.

In a news release Jorge Valadas, one of the lead researchers, said replacing the missing lipid produced promising results:

“When we model Parkinson’s disease in fruit flies, we find that they have fragmented sleep patterns and difficulties in knowing when to go to sleep or when to wake up. But when we feed them phosphatidylserine–the lipid that is depleted in the neuropeptidergic neurons–we see an improvement in a matter of days.”

Next, the team wants to see if the same lipids are low in people with Parkinson’s and if they are, look into phosphatidylserine – which is already approved in supplement form – as a means to help ease sleep problems.

Coming up with a stem cell FIX for a life-threatening blood disorder

Hemophilia

A promising new treatment option for hemophiliacs is in the works at the Salk Institute for Biological Sciences. Patients with Hemophilia B experience uncontrolled, and sometimes life threatening, bleeding due to loss or improper function of Factor IX (FIX), a protein involved in blood clotting. There is no cure for the disease and patients rely on routine infusions of FIX to prevent excessive blood loss. As you can imagine, this treatment regimen is both time consuming and expensive, while also becoming less effective over time.

Salk researchers, partially funded by CIRM, aimed to develop a more long-term solution for this devastating disease by using the body’s own cells to fix the problem.

In the study, published in the journal Cell Reports, They harvested blood cells from hemophiliacs and turned them into iPSCs (induced pluripotent stem cells), which are able to turn into any cell type. Using gene editing, they repaired the iPSCs so they could produce FIX and then turned the iPSCs into liver cells, the cell type that naturally produces FIX in healthy individuals.

One step therapy

To test whether these FIX-producing liver cells were able to reduce excess blood loss, the scientists injected the repaired human cells into a hemophiliac mouse. The results were very encouraging; they saw a greater than two-fold increase in clotting efficiency in the mice, reaching about a quarter of normal activity. This is particularly promising because other studies showed that increasing FIX activity to this level in hemophiliac humans significantly reduces bleeding rates. On top of that they also observed that these cells were able to survive and produce FIX for up to a year in the mice.

In a news release Suvasini Ramaswamy, the first author of the paper, said this method could eliminate the need for multiple treatments, as well as avoiding the immunosuppressive therapy that would be required for a whole liver transplant.

“The appeal of a cell-based approach is that you minimize the number of treatments that a patient needs. Rather than constant injections, you can do this in one shot.”

While these results provide an exciting new avenue in hemophilia treatment, there is still much more work that needs to be done before this type of treatment can be used in humans. This approach, however, is particularly exciting because it provides an important proof of principle that combining stem cell reprogramming with genetic engineering can lead to life-changing breakthroughs for treating genetic diseases that are not currently curable.

 

 

Stem Cell Roundup: The brain & obesity; iPSCs & sex chromosomes; modeling mental illness

Stem Cell Image of the Week:
Obesity-in-a-dish reveals mutations and abnormal function in nerve cells

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Image shows two types of hypothalamic neurons (in magenta and cyan) that were derived from human induced pluripotent stem cells.
Credit: Cedars-Sinai Board of Governors Regenerative Medicine Institute

Our stem cell image of the week looks like the work of a pre-historic cave dweller who got their hands on some DayGlo paint. But, in fact, it’s a fluorescence microscopy image of stem cell-derived brain cells from the lab of Dhruv Sareen, PhD, at Cedars-Sinai Medical Center. Sareen’s team is investigating the role of the brain in obesity. Since the brain is a not readily accessible organ, the team reprogrammed skin and blood cell samples from severely obese and normal weight individuals into induced pluripotent stem cells (iPSCs). These iPSCs were then matured into nerve cells found in the hypothalamus, an area of the brain that regulates hunger and other functions.

A comparative analysis showed that the nerve cells derived from the obese individuals had several genetic mutations and had an abnormal response to hormones that play a role in telling our brains that we are hungry or full. The Cedars-Sinai team is excited to use this obesity-in-a-dish system to further explore the underlying cellular changes that lead to excessive weight gain. Ultimately, these studies may reveal ways to combat the ever-growing obesity epidemic, as Dr. Sareen states in a press release:

“We are paving the way for personalized medicine, in which drugs could be customized for obese patients with different genetic backgrounds and disease statuses.”

The study was published in Cell Stem Cell

Differences found in stem cells derived from male vs female.

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Microscope picture of a colony of iPS cells. Credit: Vincent Pasque

Scientists at UCLA and KU Leuven University in Belgium carried out a study to better understand the molecular mechanisms that control the process of reprogramming adult cells back into the embryonic stem cell-like state of induced pluripotent stem cells (iPSCs). Previous studies have shown that female vs male embryonic stem cells have different patterns of gene regulation. So, in the current study, male and female cells were analyzed side-by-side during the reprogramming process.  First author Victor Pasquale explained in a press release that the underlying differences stemmed from the sex chromosomes:

In a normal situation, one of the two X chromosomes in female cells is inactive. But when these cells are reprogrammed into iPS cells, the inactive X becomes active. So, the female iPS cells now have two active X chromosomes, while males have only one. Our results show that studying male and female cells separately is key to a better understanding of how iPS cells are made. And we really need to understand the process if we want to create better disease models and to help the millions of patients waiting for more effective treatments.”

The CIRM-funded study was published in Stem Cell Reports.

Using mini-brains and CRISPR to study genetic linkage of schizophrenia, depression and bipolar disorder.

If you haven’t already picked up on a common thread in this week’s stories, this last entry should make it apparent: iPSC cells are the go-to method to gain insight in the underlying mechanisms of a wide range of biology topics. In this case, researchers at Brigham and Women’s Hospital at Harvard Medical School were interested in understanding how mutations in a gene called DISC1 were linked to several mental illnesses including schizophrenia, bipolar disorder and severe depression. While much has been gleaned from animal models, there’s limited knowledge of how DISC1 affects the development of the human brain.

The team used human iPSCs to grow cerebral organoids, also called mini-brains, which are three-dimensional balls of cells that mimic particular parts of the brain’s anatomy. Using CRISPR-Cas9 gene-editing technology – another very popular research tool – the team introduced DISC1 mutations found in families suffering from these mental disorders.

Compared to cells with normal copies of the DISC1 gene, the mutant organoids showed abnormal structure and excessive cell signaling. When an inhibitor of that cell signaling was added to the growing mutant organoids, the irregular structures did not develop.

These studies using human cells provide an important system for gaining a better understanding of, and potentially treating, mental illnesses that victimize generations of families.

The study was published in Translation Psychiatry and picked up by Eureka Alert.

Building a better brain organoid

One of the reasons why it’s so hard to develop treatments for problems in the brain – things like Alzheimer’s, autism and schizophrenia – is that you can’t do an autopsy of a living brain to see what’s going wrong. People tend to object. To get around that, scientists have used stem cells to create models of what’s happening inside the brain. They’re good, but they have their limitations. Now a team at the Salk Institute for Biological Studies has found a way to create a better brain model, and hopefully a faster route to developing new treatments.

For a few years now, scientists have been able to take skin cells from patients with neurodegenerative disorders and turn them into neurons, the kind of brain cell affected by these different diseases. They grow these cells in the lab and turn them into clusters of cells, so-called brain “organoids”, to help us better understand what’s happening inside the brain and even allow us to test medications on them to see if those treatments can help ease some symptoms.

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Human organoid tissue (green) grafted into mouse tissue. Neurons are labeled with red. Credit: Salk Institute

But those models don’t really capture the complexity of our brains – how could they – and so only offer a glimpse into what’s happening inside our skulls.

Now the team at Salk have developed a way of transplanting these organoids into mouse brains, giving them access to oxygen and nutrients that can help them not only survive longer but also display more of the characteristics found in the human brain.

In a news release, CIRM Grantee and professor at Salk’s Laboratory of Genetics, Rusty Gage said this new approach gives researchers a powerful new tool:

“This work brings us one step closer to a more faithful, functional representation of the human brain and could help us design better therapies for neurological and psychiatric diseases.”

The transplanted human brain organoids showed plenty of signs that they were becoming engrafted in the mouse brain:

  • They had blood vessels form in them and blood flowing through them
  • They formed neurons
  • They formed other brain support cells called astrocytes

They also used a series of imaging techniques to confirm that the neurons in the organoid were not just connecting but also sending signals, in essence, communicating with each other.

Abed AlFattah Mansour, a Salk research associate and the paper’s first author, says this is a big accomplishment.

“We saw infiltration of blood vessels into the organoid and supplying it with blood, which was exciting because it’s perhaps the ticket for organoids’ long-term survival. This indicates that the increased blood supply not only helped the organoid to stay healthy longer, but also enabled it to achieve a level of neurological complexity that will help us better understand brain disease.”

A better understanding of what’s going wrong is a key step in being able to develop new treatments to fix the problem.

The study is published in the journal Nature Biotechnology.

CIRM has a double reason to celebrate this work. Not only is the team leader, Rusty Gage, a CIRM grantee but one of the Salk team, Sarah Fernandes, is a former intern in the CIRM Bridges to Stem Cell Research program.

Gage-Natbiotech-press-release

From left: Sarah Fernandes, Daphne Quang, Stephen Johnston, Sarah Parylak, Rusty Gage, Abed AlFattah Mansour, Hao Li Credit: Salk Institute

Celebrating Exciting CIRM-Funded Discovery Research on World Parkinson’s Day

April 11th is World Parkinson’s Disease Awareness Day. To mark the occasion, we’re featuring the work of CIRM-funded researchers who are pursuing new, promising ideas to treat patients with this debilitating neurodegenerative disease.


Birgitt Schuele, Parkinson’s Institute

CIRM Grant: Quest Award – Discovery Stage Research

Research: Birgitt and her team at the Parkinson’s Institute in Sunnyvale, California, are using CRISPR gene editing technology to reduce the levels of a toxic protein called alpha synuclein, which builds up in the dopaminergic brain cells affected by Parkinson’s disease.

Birgitt Schuele

“My hope is that I can contribute to stopping disease progression in Parkinson’s. If we can develop a drug that can get rid of accumulated protein in someone’s brain that should stop the cells from dying. If someone has early onset PD and a slight tremor and minor walking problems, stopping the disease and having a low dose of dopamine therapy to control symptoms is almost a cure.”

Parkinson’s disease in a dish. Dopaminergic neurons made from Parkinson’s patient induced pluripotent stem cells. (Image credit: Birgitt Schuele)


Jeanne Loring, Scripps Research Institute

CIRM Grant: Quest Award – Discovery Stage Research

Research: Jeanne Loring and her team at the Scripps Research Institute in La Jolla, California, are deriving dopaminergic neurons from the iPSCs of Parkinson’s patients. Their goal is to develop a personalized, stem cell-based therapy for PD.

Jeanne Loring

“We are working toward a patient-specific neuron replacement therapy for Parkinson’s disease.  By the time PD is diagnosed, people have lost more than half of their dopamine neurons in a specific part of the brain, and loss continues over time.  No drug can stop the loss or restore the neurons’ function, so the best possible option for long term relief of symptoms is to replace the dopamine neurons that have died.  We do this by making induced pluripotent stem cells from individual PD patients and turning them into the exact type of dopamine neuron that has been lost.  By transplanting a patient’s own cells, we will not need to use potentially dangerous immunosuppressive drugs.  We plan to begin treating patients in a year to two years, after we are granted FDA approval for the clinical therapy.”

Skin cells from a Parkinson’s patient (left) were reprogrammed into induced pluripotent stem cells (center) that were matured into dopaminergic neurons (right) to model Parkinson’s disease. (Image credit: Jeanne Loring)


Justin Cooper-White, Scaled BioLabs Inc.

CIRM Grant: Quest Award – Discovery Stage Research

Research: Justin Cooper-White and his team at Scaled Biolabs in San Francisco are developing a tool that will make clinical-grade dopaminergic neurons from the iPSCs of PD patients in a rapid and cost-effective manner.

Justin Cooper-White

“Treating Parkinson’s disease with iPSC-derived dopaminergic neuron transplantation has a strong scientific and clinical rationale. Even the best protocols are long and complex and generally have highly variable quality and yield of dopaminergic neurons. Scaled Biolabs has developed a technology platform based on high throughput microfluidics, automation, and deep data which can optimize and simplify the road from iPSC to dopaminergic neuron, making it more efficient and allowing a rapid transition to GMP-grade derivation of these cells.  In our first 6 months of CIRM-funded work, we believe we have already accelerated and simplified the production of a key intermediate progenitor population, increasing the purity from the currently reported 40-60% to more than 90%. The ultimate goal of this work is to get dopaminergic neurons to the clinic in a robust and economical manner and accelerate treatment for Parkinson’s patients.”

High throughput differentiation of dopaminergic neuron progenitors in  microbioreactor chambers in Scaled Biolabs’ cell optimization platform. Different chambers receive different differentiation factors, so that optimal treatments for conversion to dual-positive cells can be determined (blue: nuclei, red: FOXA2, green: LMX1A).


Xinnan Wang, Stanford University

CIRM Grant: Basic Biology V

Research: Xinnan Wang and her team at Stanford University are studying the role of mitochondrial dysfunction in the brain cells affected in Parkinson’s disease.

Xinnan Wang

“Mitochondria are a cell’s power plants that provide almost all the energy a cell needs. When these cellular power plants are damaged by stressful factors present in aging neurons, they release toxins (reactive oxygen species) to the rest of the neuron that can cause neuronal cell death (neurodegeneration).  We hypothesized that in Parkinson’s mutant neurons, mitochondrial quality control is impaired thereby leading to neurodegeneration. We aimed to test this hypothesis using neurons directly derived from Parkinson’s patients (induced pluripotent stem cell-derived neurons).”

Dopaminergic neurons derived from human iPSCs shown in green, yellow and red. (Image credit: Atossa Shaltouki, Stanford)


Related Blogs:

Gladstone researchers tame toxic protein that carries increased Alzheimer’s risk

With a clinical trial failure rate of 99% over the past 15 years or so, the path to a cure for Alzheimer’s disease is riddled with disappointment. In many cases, candidate therapies looked very promising in pre-clinical animal studies, only to flop when tested in people. Now, a CIRM-funded Nature Medicine study by researchers at the Gladstone Institutes sheds some light on a source of this discrepancy. And more importantly, the study points to a potential treatment strategy that can remove the hallmarks of Alzheimer’s in human brain cells.

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Build up of tau protein (blue) and amyloid-beta (yellow) in and around neurons are hallmarks of the damage caused by Alzheimer’s disease. 
Image courtesy of the National Institute on Aging/National Institutes of Health.

For several decades, researchers have known the ApoE gene can influence the risk for an Alzheimer’s diagnosis in individuals 65 years and older. The gene comes in a few flavors with ApoE3 and ApoE4 differing in only one spot in their DNA sequences. Though nearly identical, the resulting ApoE3 and E4 proteins have very different shapes with differing function. In fact, people who inherit two copies of the ApoE4 gene have a twelve times higher risk for Alzheimer’s compared to those with the more common ApoE3.

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Yadong Huang

To better understand what’s happening at the cellular level, Yadong Huang, PhD and his team at the Gladstone Institutes obtained skin samples from Alzheimer’s donors carrying two copies of the ApoE4 gene and healthy donors with two copies of ApoE3. The skin cells were reprogrammed into induced pluripotent stem cells (iPSCs) and then matured into nerve cells, or neurons.

Compared to ApoE3 cells, the researchers observed that the ApoE4 neurons accumulated higher levels of proteins called p-tau and amyloid beta, which are hallmarks of Alzheimer’s disease. Repeating this same experiment in iPSC-derived mouse neurons showed no difference in the production of amyloid beta levels between the ApoE3 and E4 neurons. This result points to the importance of studying human disease in human cells, as first author Chengzhong Wang, PhD, points out in a press release:

“There’s an important species difference in the effect of apoE4 on amyloid beta. Increased amyloid beta production is not seen in mouse neurons and could potentially explain some of the discrepancies between mice and humans regarding drug efficacy. This will be very important information for future drug development.”

Further experiments aimed to answer a long sought-after question: is it the absence of ApoE3 or the presence of ApoE4 that causes the damaging effects on neurons? Using gene-editing techniques, the team removed both ApoE forms from the donor-derived neurons. The resulting cells appeared healthy but when ApoE4 was added back in, Alzheimer’s-associated problems emerged. This finding points to the toxicity of ApoE4 to neurons.

With this new insight in hand, the team examined what would happen if they converted the ApoE4 form into the ApoE3 form. The team had previously designed molecules, they dubbed “structure correctors”, that physically interact with the ApoE4 protein and cause it to take on the shape of the ApoE3 form found in healthy individuals. When these correctors were added to the ApoE4 neurons, it brought back normal function to the cells.

Given that the structure corrector is a chemical compound that works in human brain cells, it’s tantalizing to think about its possible use as a novel Alzheimer’s drug. And you can bet Dr. Huang and his group are eagerly embarking on that new path.

Stem Cell Roundup: watching brain cells in real time, building better heart cells, and the plot thickens on the adult neurogenesis debate

Here are the stem cell stories that caught our eye this week.

Watching brain cells in real time

This illustration depicts a new method that enables scientists to see an astrocyte (green) physically interacting with a neuronal synapse (red) in real time, and producing an optical signal (yellow). (Khakh Lab, UCLA Health)

Our stem cell photo of the week is brought to you by the Khakh lab at UCLA Health. The lab developed a new method that allows scientists to watch brain cells interact in real time. Using a technique called fluorescence resonance energy-transfer (FRET) microscopy, the team can visualize how astrocytes (key support cells in our central nervous system) and brain cells called neurons form connections in the mouse brain and how these connections are affected by diseases like Alzheimer’s and ALS.

Baljit Khakh, the study’s first author, explained the importance of their findings in a news release:

“This new tool makes possible experiments that we have been wanting to perform for many years. For example, we can now observe how brain damage alters the way that astrocytes interact with neurons and develop strategies to address these changes.”

The study was published this week in the journal Neuron.


Turn up the power: How to build a better heart cell (Todd Dubnicoff)

For years now, researchers have had the know-how to reprogram a donor’s skin cells into induced pluripotent stem cells (iPSCs) and then specialize them into heart muscle cells called cardiomyocytes. The intervening years have focused on optimizing this method to accurately model the biology of the adult human heart as a means to test drug toxicity and ultimately develop therapies for heart disease. Reporting this week in Nature, scientists at Columbia University report an important step toward those goals.

The muscle contractions of a beating heart occur through natural electrical impulses generated by pacemaker cells. In the case of lab-grown cardiomyocytes, introducing mechanical and electrical stimulation is required to reliably generate these cells. In the current study, the research team showed that the timing and amount of stimulation is a critical aspect to the procedure.

The iPS-derived cardiomyocytes have formed heart tissue that closely mimics human heart functionality at over four weeks of maturation. Credit: Gordana Vunjak-Novakovic/Columbia University.

The team tested three scenarios on iPSC-derived cardiomyocytes (iPSC-CMs): no electrical stimulation for 3 weeks, constant stimulation for 3 weeks, and finally, two weeks of increasingly higher stimulation followed by a week of constant stimulation. This third setup mimics the changes that occur in a baby’s heart just before and just after birth.

These scenarios were tested in 12 day-old and 28 day-old iPSC-CMs. The results show that only the 12 day-old cells subjected to the increasing amounts of stimulation gave rise to fully mature heart muscle cells. On top of that, it only took four weeks to make those cells. Seila Selimovic, Ph.D., an expert at the National Institutes of Health who was not involved in the study, explained the importance of these findings in a press release:

“The resulting engineered tissue is truly unprecedented in its similarity to functioning human tissue. The ability to develop mature cardiac tissue in such a short time is an important step in moving us closer to having reliable human tissue models for drug testing.”

Read more at: https://phys.org/news/2018-04-early-bioengineered-human-heart-cells.html#jCp


Yes we do, no we don’t. More confusion over growing new brain cells as we grow older (Kevin McCormack)

First we didn’t, then we did, then we didn’t again, now we do again. Or maybe we do again.

The debate over whether we are able to continue making new neurons as we get older took another twist this week. Scientists at Columbia University said their research shows we do make new neurons in our brain, even as we age.

This image shows what scientists say is a new neuron in the brain of an older human. A new study suggests that humans continue to make new neurons throughout their lives. (Columbia University Irving Medical Center)

In the study, published in the journal Cell Stem Cell, the researchers examined the brains of 28 deceased donors aged 14 to 79. They found similar numbers of precursor and immature neurons in all the brains, suggesting we continue to develop new brain cells as we age.

This contrasts with a UCSF study published just last month which came to the opposite conclusion, that there was no evidence we make new brain cells as we age.

In an interview in the LA Times, Dr. Maura Boldrini, the lead author on the new study, says they looked at a whole section of the brain rather than the thin tissues slices the UCSF team used:

“In science, the absence of evidence is not evidence of absence. If you can’t find something it doesn’t mean that it is not there 100%.”

Well, that resolves that debate. At least until the next study.

UC Davis researchers make stem cell-derived mini-brains that contain blood vessels

Growing neurons on a flat petri dish is a great way to study the inner workings of nerve signals in the brain. But I think it’s safe to argue that a two-dimensional lawn of cells doesn’t capture all the complexity of our intricate, cauliflower-shaped brains. Then again, cracking open the skulls of living patients is also not a viable path for fully understanding the molecular basis of brain disorders.

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Brain organoids (two white balls) growing in petri dish.
Image: Pasca Lab, Stanford University.

The recent emergence of stem cell-derived mini-brains, or brain organoids, as a research tool is bridging this impasse. With induced pluripotent stem cells (iPSCs) derived from a readily-accessible skin sample from patients, it’s possible to generate three-dimensional balls of cells that mimic particular parts of the brain’s anatomy. These mini-brains have the expected type of neurons, as well as other cells that support neuron function. We’ve written many blogs, most recently in January, on the applications of this cutting-edge tool.

With any new technology, there is always room for improvement. One thing that most mini-brains lack is their own system of blood vessels, or vasculature. That’s where Dr. Ben Waldau, a vascular neurosurgeon at UC Davis Medical Center, and his lab come into the picture. Last week, their published work in NeuroReport showed that incorporating blood vessels into a brain organoid is possible.

UCDavisorganoid

A stained cross-section of a brain organoid showing that blood vessels (in red) have penetrated both the outer, more organized layers and the inner core. Image: UC Davis Institute for Regenerative Cures

Using iPSCs from one patient, the Waldau team separately generated brain organoids and blood vessels cells, also called endothelial cells. After growing each for about a month, the organoids were embedded in a gelatin containing the endothelial cells. In an excellent Wired article, writer Megan Molteni explains what happened next:

“After incubating for three weeks, they took a single organoid and transplanted it into a tiny cavity carefully carved into a mouse’s brain. Two weeks later the organoid was alive, well—and, critically, had grown capillaries that penetrated all the way to its inner layers.”

Every tissue relies on nutrients and oxygen from the blood. As Molteni suggests, being able to incorporate blood vessels and brain organoids from the same patient’s cells may make it possible to grow and study even more complex brain structures without the need of a mouse using fluidic pumps.

As Waldau explains in the Wired article, this vascularized brain organoid system also adds promise to the ultimate goal of repairing damaged brain tissue:

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Ben Waldau

“The whole idea with these organoids is to one day be able to develop a brain structure the patient has lost made with the patient’s own cells. We see the injuries still there on the CT scans, but there’s nothing we can do. So many of them are left behind with permanent neural deficits—paralysis, numbness, weakness—even after surgery and physical therapy.”