Comparing two cellular reprogramming methods from one donor’s cells yields good news for iPSCs

In 2012, a mere six years after his discovery of induced pluripotent stem cells (iPSCs), Shinya Yamanaka was awarded the Nobel Prize in Medicine. Many Nobel winners aren’t recognized until decades after their initial groundbreaking studies. That goes to show you the importance of Yamanaka’s technique, which can reprogram a person’s cells, for example skin or blood, into embryonic stem cell-like iPSCs by just adding a small set of reprogramming factors.

These iPSCs are pluripotent, meaning they can be specialized, or differentiated, into virtually any cell type in the body. With these cells in hand, researchers have a powerful tool to study human disease and to develop treatments using human cells directly from patients. And at the same time, this cell source helps avoid the ethical concerns related to embryonic stem cells.

iPSC_Wu

Induced pluripotent stem cell (iPSC) colonies.
Image Credit: Joseph Wu

Still, there has been lingering uneasiness about how well iPSCs match up to embryonic stem cells (ESCs), considered the gold-standard of pluripotent stem cells. One source of those concerns is that the iPSC method doesn’t completely reprogram cells and they retain memory of their original cell source, in the form of chemical – also called epigenetic – modifications of the cells’ DNA structure. So, if a researcher were to make, say, heart muscle cells from iPSCs that have an epigenetic memory of its skin cell origins, any resulting conclusions about a given disease study or cell therapy could be less accurate than ESC-related results. But a report published yesterday in PNAS should help relieve these worries.

The CIRM-funded study – a collaboration between the labs of Joseph Wu and Michael Synder at Stanford University and Shoukhrat Mitalipov at Oregon Health & Science University – carried out an exhaustive series of experiments that carefully compared the gene activity and cell functions of iPSC-derived cells with cells derived from embryonic stem cells. The teams sought to compare cells generated from the same person to be sure any differences were not the result of genetics. To make this “apples-to-apples” comparison, they generated embryonic stem cells using another reprogramming technique called somatic cell nuclear transfer (SCNT).

With SCNT, a nucleus from an adult cell is transferred to an egg which has its own nucleus removed. The resulting cell becomes reprogrammed back into an embryo from which embryonic stem cells are generated – the researchers call them NT-ESCs for short. In this study, the skin cell sample used for making the iPSCs and the cell nucleus used for making the NT-ESCs came from the same person. In scientific lingo, the iPSCs and SCNT stem cells are considered isogenic.

Now, it turns out the NT-ESC reprogramming process is more complete and eliminates epigenetic memory of the original cell source. So why even bother with iPSCs if you have NT-ESCs? There are big disadvantages with SCNT: it’s a complex technique – only a limited number of labs pull it off – and it requires donated human eggs which carries ethical issues. So, if a direct comparison iPSCs and SNCT stem cells shows little difference then it would be fair to argue that iPSCs can replace NT-ESCs for deriving patient-specific stem cells.

And that’s exactly what the teams found, as Dr. Wu summarized it to me in an interview:

“Direct comparison between differentiated cells derived from iPSCs and SCNT had never been performed because it had been difficult to generate patient-specific ESCs by the SCNT method. Collaborating with Dr. Shoukhrat Mitalipov at Oregon Health & Science University and Dr. Michael Snyder at Stanford University, we compared patient-specific cardiomocytes (heart muscle cells) and endothelial (blood vessel) cells derived by these two reprogramming methods (SCNT and iPSCs) and found they were relatively equivalent regarding molecular and functional features.”

PSC-ECs2 copy

Blood vessel cells derived by iPSC (left) and SCNT (right) reprogramming methods.
Image credit: Joseph Wu

Because the heart muscle and blood vessel cells were similar regardless of reprogramming method, it suggests that the epigenetic memory that remained in the iPSCs is less of a worry. Dr. Wu explained to me this way:

joewu

Joseph Wu

“If iPSCs carry substantial epigenetic memory of the cell-of-origin, it is unlikely these iPSCs can differentiate to a functional cardiac cell or blood vessel cell. Only the stem cells free of significant epigenetic memory can differentiate into functional cells.”

 

Hopefully these results hold up over time because it will bode well for the countless iPSC-related disease studies as well as the growing number of iPSC-related projects that are nearing clinical trials.

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CIRM-Funded Clinical Trials Targeting the Heart, Pancreas, and Kidneys

This blog is part of our Month of CIRM series, which features our Agency’s progress towards achieving our mission to accelerate stem cell treatments to patients with unmet medical needs.

This week, we’re highlighting CIRM-funded clinical trials to address the growing interest in our rapidly expanding clinical portfolio. Today we are featuring trials in our organ systems portfolio, specifically focusing on diseases of the heart/vasculature system, the pancreas and the kidneys.

CIRM has funded a total of nine trials targeting these disease areas, and eight of these trials are currently active. Check out the infographic below for a list of our currently active trials.

For more details about all CIRM-funded clinical trials, visit our clinical trials page and read our clinical trials brochure which provides brief overviews of each trial.

Attractive new regenerative medicine tool uses magnets to shape and stimulate stem cells

The ultimate goal of tissue engineers who work in the regenerative medicine field is to replace damaged or diseased organs with new ones built from stem cells. To accomplish the feat, these researchers are developing new tools and techniques to manipulate and specialize stem cells into three dimensional structures. Some popular methods – which we’ve blogged about often – include the use of bioscaffolds as well as 3D bioprinting . This week, a research team at the Laboratoire Matière et Systèmes Complexes in France has developed an attractive (pun intended!) new tool that uses magnetized stem cells to both manipulate and stimulate the cells into 3D shapes.

The magnetic stretcher: this all-in-one system can both form and mechanically stimulate an aggregate of magnetized embryonic stem cells. Image: © Claire Wilhelm / Laboratoire Matière et systèmes complexes (CNRS/Université Paris Diderot).

The study, reported on Monday in Nature Communications, used embryonic stem cells which were incubated with magnetic nanoparticles. The cells readily take up the nanoparticles which allowed the scientists to group the individual cells using magnets. But first the team needed to show that the nanoparticles had no negative effects on the cells. Comparing the iron nanoparticle-laden stem cells to iron-free cells showed no difference in the cells’ survival and their ability to divide.

It was also important to make sure the introduction of nanoparticles had no impact on the stem cell’s pluripotency; that is, its ability to maintain its unspecialized state. A visual check of the cells through a microscope showed that they grew together in rounded clumps, a hallmark of undifferentiated, pluripotent cells. In addition, the key genes that bestow pluripotency onto embryonic stem cells were still active after the addition of the nanoparticles.

The stem cells’ ability to mature into various cell types, like heart muscle or nerve, is key to any successful tissue engineering project. So, the next important assessment of these magnetized cells was to make sure their ability to differentiate, or specialize, was still intact. The typical first step to differentiating embryonic stem cells is to form so-called embryoid bodies (EBs), which are 3D groups of pluripotent stem cells which begin differentiating into the three fundamental tissues types: mesoderm (gives rise to muscle, bone, fat), ectoderm (gives rise to nerve, hair, eyes), endoderm (gives rise to intestines, liver). Using a popular technique, called the hanging drop method, the team showed that the presence of the nanoparticles did not negatively affect embryoid body formation.

In fact, the use of magnets to form embryoid bodies provided several advantages over the hanging drop method. The hanging drop technique requires multiple, time-consuming steps and the resulting embryoid bodies tend to be inconsistent in size and shape. Use of the magnets, on the other hand, instantaneously assembled the stem cells into consistently round aggregates. And by precisely adjusting the magnetic force used, the scientists could also vary the size of the embyroid body, which is an important variable to control since the embryoid size can impact its ability to differentiate.

While the magnet used to form the embryoid bodies was kept stable, the researchers included another magnet which they could move. With this setup, the team was able to stretch and shape the group of cells without the need of scaffolds or the need to physically contact the cells. Several previous studies, using flat, 2-dimensional petri dishes, have shown that the stiffness and flexibility of the dish can stimulate gene activity by affecting cell shape. In this study, the researchers found that when the magnet was moved in a cyclical pattern that imitates the rhythm of a heart beat, the embryoid bodies were, if you can believe it, nudged toward a heart muscle fate. A press release by France’s National Center of Scientific Research (CNRS), which funded the study, explained the big picture implications of this new technique:

“This “all-in-one” approach, which makes it possible to build and manipulate tissue within the same system, could thus prove to be a powerful tool both for biophysical studies and tissue engineering.”

Hearts and brains are center stage at CIRM Patient Advocate event

Describing the work of a government agency is not the most exciting of topics. Books on the subject would probably be found in the “Self-help for Insomniacs” section of a good bookstore (there are still some around). But at CIRM we are fortunate. When we talk about what we do, we don’t talk about the mechanics of our work, we talk about our mission: accelerating stem cell therapies to people with unmet medical needs.

Yesterday at the Gladstone Institutes in San Francisco we did just that, talking about the progress being made in stem cell research to an audience of friends, supporters and patient advocates. We had a lot to talk about, including the 35 clinical trials we have funded so far, and our goals and hopes for the future.

We were lucky to have Dr. Deepak Srivastava and Dr. Steve Finkbeiner from Gladstone join us to talk about their work. Some people are good scientists, some are good communicators. Deepak and Steve are great scientists and equally great communicators.

Deepak Srivastava highlighted ongoing stem cell research at the Gladstone
(Photo: Todd Dubnicoff/CIRM)

Deepak is the Director of the Roddenberry Stem Cell Center at Gladstone (and yes, it’s named after Gene Roddenberry of Star Trek fame) and an expert on heart disease. He talked about how advances in research have enabled us to turn heart scar tissue cells into new heart muscle cells, creating the potential to use a person’s own cells to help them recover from a heart attack.

“If you have a heart attack, your heart turns that muscle into scar tissue which affects the heart’s ability to pump blood around the body. We identified a combination of factors that support cells that are already in your heart and we have found a way of converting those scar cells into muscle. This could help repair the heart enough so you may not need a transplant, but you can lead a much more normal life.”

He said this research is now advancing to the point where they hope it could be ready for testing in people in the not too distant future and joked that his father, who has had a heart attack, volunteered to be the second person to try it. “Not the first but definitely the second.”

Steve, who is the Director of the Taube/Koret Center for Neurodegenerative Disease Research, specializes in problems in the brain; everything from Alzheimer’s and Parkinson’s to schizophrenia and ALS (also known as Lou Gehrig’s disease.

He talked about his uncle, who has end stage Parkinson’s disease, and how he sees first-hand how devastating this neurodegenerative disease is, and how that personal connection helps motivate him to work ever harder.

He talked about how so many therapies that look promising in mice fail when they are tested in people:

“A huge motivation for me has been to try and figure out a more reliable way to test these potential therapies and to move discoveries from the lab and into clinical trials in patients.”

Steve is using ordinary skin cells or tissue samples, taken from people with Parkinson’s and Alzheimer’s and other neurological conditions, and using the iPSC technique developed by Shinya Yamanaka (who is a researcher at Gladstone and also Director of CIRA in Japan) turns them into the kinds of cells found in the brain. These cells then enable him to study how these different diseases affect the brain, and come up with ways that might stop their progress.

Steve Finkbeiner is using human stem cells to model brain diseases
(Photo: Todd Dubnicoff/CIRM)

He uses a robotic microscope – developed at Gladstone – that allows his team to study these cells and test different potential therapies 24 hours a day, seven days a week. This round-the-clock approach will hopefully help speed up his ability to find something that help patients.

The CIRM speakers – Dr. Maria Millan, our interim President and CEO – and Sen. Art Torres (ret.) the Vice Chair of our Board and a patient advocate for colorectal cancer – talked about the progress we are making in helping push stem cell research forward.

Dr. Millan focused on our clinical trial work and how our goal is to create a pipeline of promising projects from the work being done by researchers like Deepak and Steve, and move those out of the lab and into clinical trials in people as quickly as possible.

Sen. Art Torres (Ret.)
(Photo: Todd Dubnicoff/CIRM)

Sen. Torres focused on the role of the patient advocate at CIRM and how they help shape and influence everything we do, from the Board’s deciding what projects to support and fund, to our creating Clinical Advisory Panels which involve a patient advocate helping guide clinical trial teams.

The event is one of a series that we hold around the state every year, reporting back to our friends and supporters on the progress being made. We feel, as a state agency, that we owe it to the people of California to let them know how their money is being spent.

We are holding two more of these events in the near future, one at UC Davis in Sacramento on October 10th, and one at Cedars-Sinai Medical Center in Los Angeles on October 30th.

Stem cell stories that caught our eye: bubble baby therapy a go in UK, in-utero stem cell trial and novel heart disease target

There were lots of CIRM mentions in the news this week. Here are two brief recaps written by Karen Ring to get you up to speed. A third story by Todd Dubnicoff summarizes an promising finding related to heart disease by researchers in Singapore.  

CIRM-funded “bubble baby” disease therapy gets special designation by UK.
Orchard Therapeutics, a company based in the UK and the US, is developing a stem cell-based gene therapy called OTL-101 to treat a primary immune disease called adenosine-deaminase deficient severe combined immunodeficiency (ADA-SCID), also known as “bubble baby disease”. CIRM is funding a Phase 1/2 clinical trial led by Don Kohn of UCLA in collaboration with Orchard and the University College in London.

In July, the US Food and Drug Administration (FDA) awarded OTL-101 Rare Pediatric Disease Designation (read more about it here), which makes the therapy eligible for priority review by the FDA, and could give it a faster route to being made more widely available to children in need.

On Tuesday, Orchard announced further good news that OTL-101 received “Promising Innovative Medicine Designation” by the UK’s Medicines and Healthcare Products Regulatory Agency (MHRA). In a news release, the company explained how this designation bodes well for advancing OTL-101 from clinical trials into patients,

“The designation as Promising Innovative Medicine is the first step of a two-step process under which OTL-101 can benefit from the Early Access to Medicine Scheme (“EAMS”). Nicolas Koebel, Senior Vice President for Business Operations at Orchard, added: “With this PIM designation we can potentially make OTL-101 available to UK patients sooner under the Early Access to Medicine Scheme”.

CIRM funded UCSF clinical trial mentioned in SF Business Times
Ron Leuty, reporter at the San Francisco Business Times, published an article about a CIRM-funded trial out of UCSF that is targeting a rare genetic blood disease called alpha thalassemia major, describing it as, “The world’s first in-utero blood stem cell transplant, soon to be performed at the University of California, San Francisco, could point the way toward pre-birth cures for a range of blood diseases, such as sickle cell disease.”

Alpha Thalassemia affects the ability of red blood cells to carry oxygen because of a reduction in a protein called hemoglobin. The UCSF trial, spearheaded by UCSF Pediatric surgeon Dr. Tippi MacKenzie, is hoping to use stem cells from the mother to treat babies in the womb to give them a better chance at surviving after birth.

In an interview with Leuty, Tippi explained,

“Our goal is to put in enough cells so the baby won’t need another transplant. But even if we fall short, if we can just establish 1 percent maternal cells circulating in the child, it will establish tolerance and then they can get the booster transplant.”

She also emphasized the key role that CIRM funded played in the development and launch of this clinical trial.

“CIRM is about more than funding for studies, MacKenzie said. Agency staff has provided advice about how to translate animal studies into work in humans, she said, as well as hiring an FDA consultant, writing an investigational new drug application and setting up a clinical protocol.”

“I’m a clinician, but running a clinical trial is different,” MacKenzie said. “CIRM’s been incredibly helpful in helping me navigate that.”

Heart, heal thyself: the story of Singheart
When you cut your finger or scrape a knee, a scab forms, allowing the skin underneath to regenerate and repair itself. The heart is not so lucky – it has very limited self-healing abilities. Instead, heart muscle cells damaged after a heart attack form scar tissue, making each heart beat less efficient. This condition can lead to chronic heart disease, the number one killer of both men and women in the US.

A mouse heart cell with 2 nuclei (blue) and Singheart RNA labelled by red fluorescent dyes.
Credit: A*STAR’s Genome Institute of Singapore

Research has shown that newborn mice retain the ability to completely regenerate and repair injuries to the heart because their heart muscle cells, or cardiomyocytes, are still able to divide and replenish damaged cells. But by adulthood, the mouse cardiomyocytes lose the ability to stimulate the necessary cell division processes. A research team in Singapore wondered what was preventing cardiomyocytes cell division in adult mice and if there was some way to lift that block.

This week in Nature Communications, they describe the identification of a molecule they call Singheart that may be the answer to their questions. Using tools that allow the analysis of gene activity in single cells revealed that a rare population of diseased cardiomyocytes are able to crank up genes related to cell division. And further analysis showed Singheart, a specialized genetic molecule called a long non-coding RNA, played a role in blocking this cell division gene.

As lead author Dr. Roger Foo, a principal investigator at Genome Institute of Singapore (GIS) and the National University Health System (NUHS), explained in a press release, these findings may lead to new self-healing strategies for heart disease,

“There has always been a suspicion that the heart holds the key to its own healing, regenerative and repair capability. But that ability seems to become blocked as soon as the heart is past its developmental stage. Our findings point to this potential block that when lifted, may allow the heart to heal itself.”

Treatments, cures and clinical trials: an in-person update on CIRM’s progress

Patients and Patient Advocates are at the heart of everything we do at CIRM. That’s why we are holding three free public events in the next few months focused on updating you on the stem cell research we are funding, and our plans for the future.

Right now we have 33 projects that we have funded in clinical trials. Those range from heart disease and stroke, to cancer, diabetes, ALS (Lou Gehrig’s disease), two different forms of vision loss, spinal cord injury and HIV/AIDS. We have also helped cure dozens of children battling deadly immune disorders. But as far as we are concerned we are only just getting started.

Over the course of the next few years, we have a goal of adding dozens more clinical trials to that list, and creating a pipeline of promising therapies for a wide range of diseases and disorders.

That’s why we are holding these free public events – something we try and do every year. We want to let you know what we are doing, what we are funding, how that research is progressing, and to get your thoughts on how we can improve, what else we can do to help meet the needs of the Patient Advocate community. Your voice is important in helping shape everything we do.

The first event is at the Gladstone Institutes in San Francisco on Wednesday, September 6th from noon till 1pm. The doors open at 11am for registration and a light lunch.

Gladstone Institutes

Here’s a link to an Eventbrite page that has all the information about the event, including how you can RSVP to let us know you are coming.

We are fortunate to be joined by two great scientists, and speakers – as well as being CIRM grantees-  from the Gladstone Institutes, Dr. Deepak Srivastava and Dr. Steve Finkbeiner.

Dr. Srivastava is working on regenerating heart muscle after it has been damaged. This research could not only help people recover from a heart attack, but the same principles might also enable us to regenerate other organs damaged by disease. Dr. Finkbeiner is a pioneer in diseases of the brain and has done ground breaking work in both Alzheimer’s and Huntington’s disease.

We have two other free public events coming up in October. The first is at UC Davis in Sacramento on October 10th (noon till 1pm) and the second at Cedars-Sinai in Los Angeles on October 30th (noon till 1pm). We will have more details on these events in the coming weeks.

We look forward to seeing you at one of these events and please feel free to share this information with anyone you think might be interested in attending.

How mice and zebrafish are unlocking clues to repairing damaged hearts

Bee-Gees

The Bee Gees, pioneers in trying to find ways to mend a broken heart. Photograph: Michael Ochs Archives

This may be the first time that the Australian pop group the Bee Gees have ever been featured in a blog about stem cell research, but in this case I think it’s appropriate. One of the Bee Gees biggest hits was “How can you mend a broken heart” and while it was a fine song, Barry and Robin Gibb (who wrote the song) never really came up with a viable answer.

Happily some researchers at the University of Southern California may succeed where Barry and Robin failed. In a study, published in the journal Nature Genetics, the USC team identify a gene that may help regenerate damaged heart tissue after a heart attack.

When babies are born they have a lot of a heart muscle cell called a mononuclear diploid cardiomyocyte or MNDCM for short. This cell type has powerful regenerative properties and so is able to rebuild heart muscle. However, as we get older we have less and less MNDCMs. By the time most of us are at an age where we are most likely to have a heart attack we are also most likely to have very few of these cells, and so have a limited ability to repair the damage.

Michaela Patterson, and her colleagues at USC, set out to find ways to change that. They found that in some adult mice less than 2 percent of their heart cells were MNDCMs, while other mice had a much higher percentage, around 10 percent. Not surprisingly the mice with the higher percentage of MNDCMs were better able to regenerate heart muscle after a heart attack or other injury.

So the USC team – with a little help from CIRM funding – dug a little deeper and did a genome-wide association study of these mice, that’s where they look at all the genetic variants in different individuals to see if they can spot common traits. They found one gene, Tnni3k, that seems to play a key role in generating MNDCMs.

Turning Tnni3K off in mice resulted in higher numbers of MNDCMs, increasing their ability to regenerate heart muscle. But when they activated Tnni3k in zebrafish it reduced the number of MNDCMs and impaired the fish’s ability to repair heart damage.

While it’s a long way from identifying something interesting in mice and zebrafish to seeing if it can be used to help people, Henry Sucov, the senior author on the study, says these findings represent an important first step in that direction:

“The activity of this gene, Tnni3k, can be modulated by small molecules, which could be developed into prescription drugs in the future. These small molecules could change the composition of the heart over time to contain more of these regenerative cells. This could improve the potential for regeneration in adult hearts, as a preventative strategy for those who may be at risk for heart failure.”

 

 

 

Family, faith and funding from CIRM inspire one patient to plan for his future

Caleb Sizemore speaks to the CIRM Board at the June 2017 ICOC meeting.

Having been to many conferences and meetings over the years I have found there is a really simple way to gauge if someone is a good speaker, if they have the attention of people in the room. You just look around and see how many people are on their phones or laptops, checking their email or the latest sports scores.

By that standard Caleb Sizemore is a spellbinding speaker.

Last month Caleb spoke to the CIRM Board about his experiences in a CIRM-funded clinical trial for Duchenne Muscular Dystrophy. As he talked no one in the room was on their phone. Laptops were closed. All eyes and ears were on him.

To say his talk was both deeply moving and inspiring is an understatement. I could go into more detail but it’s so much more powerful to hear it from  Caleb himself. His words are a reminder to everyone at CIRM why we do this work, and why we have to continue to do all that we can to live up to our mission statement and accelerate stem cell treatments to patients with unmet medical needs.

Video produced by Todd Dubnicoff/CIRM


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One day, scientists could grow the human cardiovascular system from stem cells

The human cardiovascular system is an intricate, complex network of blood vessels that include arteries, capillaries and veins. These structures distribute blood from the heart to all parts of the body, from our head to our toes, and back again.

This week, two groups of scientists published studies showing that they can create key components of the human cardiovascular system from human pluripotent stem cells. These technologies will not only be valuable for modeling the cardiovascular system, but also for developing transplantable tissues to treat patients with cardiovascular or vascular diseases.

Growing capillaries using 3D printers

Scientists from Rice University and the Baylor College of Medicine are using 3D printers to make functioning capillaries. These are tiny, thin vessels that transport blood from the arteries to the veins and facilitate the exchange of oxygen, nutrients and waste products between the blood and tissues. Capillaries are made of a single layer of endothelial cells stitched together by cell structures called tight junctions, which create an impenetrable barrier between the blood and the body.

In work published in the journal Biomaterials Science, the scientists discovered two materials that coax human stem cell-derived endothelial cells to develop into capillary-like structures. They found that adding mesenchymal stem cells to the process, improved the ability of the endothelial cells to form into the tube-like structures resembling capillaries. Lead author on the study, Gisele Calderon, explained their initial findings in an interview with Phys.org,

“We’ve confirmed that these cells have the capacity to form capillary-like structures, both in a natural material called fibrin and in a semisynthetic material called gelatin methacrylate, or GelMA. The GelMA finding is particularly interesting because it is something we can readily 3-D print for future tissue-engineering applications.”

Scientists grow capillaries from stem cells using 3D gels. (Image Credit: Jeff Fitlow/Rice University)

The team will use their 3D printing technology to develop more accurate models of human tissues and their vast network of capillaries. Their hope is that these 3D printed tissues could be used for more accurate drug testing and eventually as implantable tissues in the clinic. Co-senior author on the study, Jordan Miller, summarized potential future applications nicely.

“Ultimately, we’d like to 3D print with living cells … to create fully vascularized tissues for therapeutic applications. You could foresee using these 3D printed tissues to provide a more accurate representation of how our bodies will respond to a drug. The potential to build tissue constructs made from a particular patient represents the ultimate test bed for personalized medicine. We could screen dozens of potential drug cocktails on this type of generated tissue sample to identify candidates that will work best for that patient.”

Growing functioning arteries

In a separate study published in the journal PNAS, scientists from the University of Wisconsin-Madison and the Morgridge Institute reported that they can generate functional arterial endothelial cells, which are cells that line the insides of human arteries.

The team used a lab technique called single-cell RNA sequencing to identify important signaling factors that coax human pluripotent stem cells to develop into arterial endothelial cells. The scientists then used the CRISPR/Cas9 gene editing technology to develop arterial “reporter cell lines”, which light up like Christmas trees when candidate factors are successful at coaxing stem cells to develop into arterial endothelial cells.

Arterial endothelial cells derived from human pluripotent stem cells. (The Morgridge Institute for Research)

Using this two-pronged strategy, they generated cells that displayed many of the characteristic functions of arterial endothelial cells found in the body. Furthermore, when they transplanted these cells into mice that suffered a heart attack, the cells helped form new arteries and improved the survival rate of these mice significantly. Mice who received the transplanted cells had an 83% survival rate compared to untreated mice who only had a 33% survival rate.

In an interview with Genetic Engineering & Biotechnology News, senior author on the study James Thomson, explained the significance of their findings,

“Our ultimate goal is to apply this improved cell derivation process to the formation of functional arteries that can be used in cardiovascular surgery. This work provides valuable proof that we can eventually get a reliable source for functional arterial endothelial cells and make arteries that perform and behave like the real thing.”

In the future, the scientists have set their sights on developing a universal donor cell line that can treat large populations of patients without fear of immune rejection. With cardiovascular disease being the leading cause of death around the world, the demand for such a stem cell-based therapy is urgent.

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

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

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

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

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

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

Sekar Kathiresan, Photo: Broad Institute

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

 

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

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

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