A better, faster, more effective way to edit genes

Clinical fellow Brian Shy talks with postdoctoral scholar Tori Yamamoto in the Marson Lab at Gladstone Institutes on June 8th, 2022. Photo courtesy Gladstone Institutes.

For years scientists have been touting the potential of CRISPR, a gene editing tool that allows you to target a specific mutation and either cut it out or replace it with the corrected form of the gene. But like all new tools it had its limitations. One important one was the difficult in delivering the corrected gene to mature cells in large numbers.

Scientists at the Gladstone Institutes and U.C. San Francisco say they think they have found a way around that. And the implications for using this technique to develop new therapies for deadly diseases are profound.

In the past scientists used inactivated viruses as a way to deliver corrected copies of the gene to patients. We have blogged about UCLA’s Dr. Don Kohn using this approach to treat children born with SCID, a deadly immune disorder. But that was both time consuming and expensive.

CRISPR, on the other hand, showed that it could be easier to use and less expensive. But getting it to produce enough cells for an effective therapy proved challenging.

The team at Gladstone and UCSF found a way around that by switching from using CRISPR to deliver a double-stranded DNA to correct the gene (which is toxic to cells in large quantities), and instead using CRISPR to deliver a single stranded DNA (you can read the full, very technical description of their approach in the study they published in the journal Nature Biotechnology).

Alex Marson, MD, PhD, director of the Gladstone-UCSF Institute of Genomic Immunology and the senior author of the study, said this more than doubled the efficiency of the process. “One of our goals for many years has been to put lengthy DNA instructions into a targeted site in the genome in a way that doesn’t depend on viral vectors. This is a huge step toward the next generation of safe and effective cell therapies.”

It has another advantage too, according to Gladstone’s Dr. Jonathan Esensten, an author of the study. “This technology has the potential to make new cell and gene therapies faster, better, and less expensive.”

The team has already used this method to generate more than one billion CAR-T cells – specialized immune system cells that can target cancers such as multiple myeloma – and says it could also prove effective in targeting some rare genetic immune diseases.

The California Institute for Regenerative Medicine (CIRM) helped support this research. Authors Brian Shy and David Nguyen were supported by the CIRM:UCSF Alpha Stem Cell Clinic Fellowship program.

How some brilliant research may have uncovered a potential therapy for Alzheimer’s 

Dr. Nicole Koutsodendris, photo courtesy Gladstone Institutes

In the world of scientific research, the people doing clinical trials tend to suck up all the oxygen in the room. They’re the stars, the ones who are bringing potential therapies to patients. However, there’s another group of researchers who toil away in the background, but who are equally deserving of praise and gratitude. 

Dr. Lana Zholudeva, photo courtesy Gladstone Institutes

These are the scientists who do basic or discovery-level research. This is where all great therapies start. This is where a researcher gets an idea and tests it to see if it holds promise. A good idea and a scientist who asks a simple question, “I wonder if…..”  

Dr. Yadong Huang, Photo courtesy Gladstone Institutes

In our latest “Talking ‘Bout (re)Generation” podcast we talk to three researchers who are asking those questions and getting some truly encouraging answers. They are scientists at the Gladstone Institutes in San Francisco: one seasoned scientist and two young post-docs trying to make a name for themselves. And they might just have discovered a therapy that could help people battling Alzheimer’s disease. 

Enjoy the podcast.


  

Newly-developed Organoid Mimics How Gut and Heart Tissues Arise Cooperatively From Stem Cells 

Microscopy image of the new type of organoid created by Todd McDevitt, Ana Silva, and their colleagues in which heart tissue (red, purple, and orange masses) and gut tissue (blue and green masses) are growing together. Captured by Ana Silva.
Microscopy image of the new type of organoid created by Todd McDevitt, Ana Silva, and their colleagues in which heart tissue (red, purple, and orange masses) and gut tissue (blue and green masses) are growing together. Captured by Ana Silva. Image courtesy of Gladstone Institutes.

Scientists at Gladstone Institutes have discovered how to grow a first-of-its-kind organoid—a three-dimensional, organ-like cluster of cells—that mimics how gut and heart tissues arise cooperatively from stem cells.  

The study was supported by a grant from CIRM and the Gladstone BioFulcrum Heart Failure Research Program. 

Gladstone Senior Investigator Todd McDevitt, PhD said this first-of-its-kind organoid could serve as a new tool for laboratory research and improve our understanding of how developing organs and tissues cooperate and instruct each other. 

McDevitt’s team creates heart organoids from human induced pluripotent stem cells, coaxing them into becoming heart cells by growing them in various cocktails of nutrients and other naturally occurring substances. In this case, the scientists tried a different cocktail to potentially allow a greater variety of heart cells to form. 

To their surprise, they found that the new cocktail led to organoids that contained not only heart, but also gut cells. 

“We were intrigued because organoids normally develop into a single type of tissue—for example, heart tissue only,” says Ana Silva, PhD, a postdoctoral scholar in the McDevitt Lab and first author of the new study. “Here, we had both heart and gut tissues growing together in a controlled manner, much as they would in a normal embryo.” 

Shown here is the study’s first author, Ana Silva, a postdoctoral scholar in the McDevitt Lab. Image courtesy of Gladstone Institutes.

The researchers also found that compared to conventional heart organoids, the new organoids resulted in much more complex and mature heart structures—including some resembling more mature-like blood vessels. 

These organoids offer a promising new look into the relationship between developing tissues, which has so far relied on growing single-tissue organoids separately and then attempting to combine them. Not only that, the organoids could help clarify how the process of human development can go wrong and provide insight on congenital disorders like chronic atrial and intestinal dysrhythmias that are known to affect both heart and gut development. 

“Once it became clear that the presence of the gut tissue contributed to the maturity of the heart tissue, we realized we had arrived at something new and special,” says McDevitt. 

Read the official release about this study on Gladstone’s website

The study findings are published in the journal Cell Stem Cell.

Creating a diverse group of future scientists

Students in CIRM’s Bridges program showing posters of their work

If you have read the headlines lately, you’ll know that the COVID-19 pandemic is having a huge impact on the shipping industry. Container vessels are forced to sit out at anchor for a week or more because there just aren’t enough dock workers to unload the boats. It’s a simple rule of economics, you can have all the demand you want but if you don’t have the people to help deliver on the supply side, you are in trouble.

The same is true in regenerative medicine. The field is expanding rapidly and that’s creating a rising demand for skilled workers to help keep up. That doesn’t just mean scientists, but also technicians and other skilled individuals who can ensure that our ability to manufacture and deliver these new therapies is not slowed down.

That’s one of the reasons why CIRM has been a big supporter of training programs ever since we were created by the voters of California when they approved Proposition 71. And now we are kick-starting those programs again to ensure the field has all the talented workers it needs.

Last week the CIRM Board approved 18 programs, investing more than $86 million, as part of the Agency’s Research Training Grants program. The goal of the program is to create a diverse group of scientists with the knowledge and skill to lead effective stem cell research programs.

The awards provide up to $5 million per institution, for a maximum of 20 institutions, over five years, to support the training of predoctoral graduate students, postdoctoral trainees, and/or clinical trainees.

This is a revival of an earlier Research Training program that ran from 2006-2016 and trained 940 “CIRM Scholars” including:

• 321 PhD students
• 453 Postdocs
• 166 MDs

These grants went to academic institutions from UC Davis in Sacramento to UC San Diego down south and everywhere in-between. A 2013 survey of the students found that most went on to careers in the industry.

  • 56% continued to further training
  • 14% advanced to an academic research faculty position
  • 10.5% advanced to a biotech/industry position
  • 12% advanced to a non-research position such as teaching, medical practice, or foundation/government work

The Research Training Grants go to:

AWARDINSTITUTIONTITLEAMOUNT
EDUC4-12751Cedars-SinaiCIRM Training Program in Translational Regenerative Medicine    $4,999,333
EDUC4-12752UC RiversideTRANSCEND – Training Program to Advance Interdisciplinary Stem Cell Research, Education, and Workforce Diversity    $4,993,115
EDUC4-12753UC Los AngelesUCLA Training Program in Stem Cell Biology    $5 million
EDUC4-12756University of Southern CaliforniaTraining Program Bridging Stem Cell Research with Clinical Applications in Regenerative Medicine    $5 million
EDUC4-12759UC Santa CruzCIRM Training Program in Systems Biology of Stem Cells    $4,913,271
EDUC4-12766Gladstone Inst.CIRM Regenerative Medicine Research Training Program    $5 million
EDUC4-12772City of HopeResearch Training Program in Stem Cell Biology and Regenerative Medicine    $4,860,989
EDUC4-12782StanfordCIRM Scholar Training Program    $4,974,073
EDUC4-12790UC BerkeleyTraining the Next Generation of Biologists and Engineers for Regenerative Medicine    $4,954,238
EDUC4-12792UC DavisCIRM Cell and Gene Therapy Training Program 2.0    $4,966,300
EDUC4-12802Children’s Hospital of Los AngelesCIRM Training Program for Stem Cell and Regenerative Medicine Research    $4,999,500
EDUC4-12804UC San DiegoInterdisciplinary Stem Cell Training Grant at UCSD III    $4,992,446
EDUC4-12811ScrippsTraining Scholars in Regenerative Medicine and Stem Cell Research    $4,931,353
EDUC4-12812UC San FranciscoScholars Research Training Program in Regenerative Medicine, Gene Therapy, and Stem Cell Research    $5 million
EDUC4-12813Sanford BurnhamA Multidisciplinary Stem Cell Training Program at Sanford Burnham Prebys Institute, A Critical Component of the La Jolla Mesa Educational Network    $4,915,671  
EDUC4-12821UC Santa BarbaraCIRM Training Program in Stem Cell Biology and Engineering    $1,924,497
EDUC4-12822UC IrvineCIRM Scholars Comprehensive Research Training Program  $5 million
EDUC4-12837Lundquist Institute for Biomedical InnovationStem Cell Training Program at the Lundquist Institute    $4,999,999

These are not the only awards we make to support training the next generation of scientists. We also have our SPARK and Bridges to Stem Cell Research programs. The SPARK awards are for high school students, and the Bridges program for graduate or Master’s level students.

Heads or tails? Stem cells help guide the decision

Two cell embryo

There are many unknown elements for what triggers the cells in an embryo to start dividing and multiplying and becoming every single cell in the body. Now researchers at the Gladstone Institutes in San Francisco have uncovered one of those elements, how embryos determine which cells become the head and which the tail.

In this CIRM-funded study the Gladstone team, led by Dr. Todd McDevitt, discovered almost by chance how the cells align in a heads-to-tail arrangement.

Todd McDevitt

They had created an organoid made from brain cells when they noticed that some of the cells were beginning to gather in an elongated fashion, in the same way that spinal cords do in a developing fetus.

In a news article, Nick Elder, a graduate student at Gladstone and the co-author of the study, published in the journal Development, says this was not what they had anticipated would happen: “Organoids don’t typically have head-tail directionality, and we didn’t originally set out to create an elongating organoid, so the fact that we saw this at all was very surprising.”

Further study enabled the team to identify which molecules were involved in signaling specific genes to switch on and off. These were similar to the process previously identified in developing mouse embryos.

“This is such a critical point in the early development of any organism, so having a new model to observe it and study it in the lab is very exciting,” says McDevitt.

This is not just of academic interest either, it could have real world implications in helping understand what causes miscarriages or birth defects.

“We can use this organoid to get at unresolved human developmental questions in a way that doesn’t involve human embryos,” says Dr. Ashley Libby, another member of the team. “For instance, you could add chemicals or toxins that a pregnant woman might be exposed to, and see how they affect the development of the spinal cord.”

How stem cells play “follow the leader”

Todd McDevitt, PhD., Photo: courtesy Gladstone Institutes

It’s hard enough trying to follow the movements of individuals in a crowd of people but imagine how much harder it is to follow the movements of stem cells, crowded into a tiny petri dish. Well, researchers at the Gladstone Institutes in San Francisco have done just that.

In a CIRM-funded study ($5.85M) Dr. Todd McDevitt and his team created a super smart artificial intelligence way of tracking the movements of hundreds of stem cells growing together in a colony, and even identify “leaders” in the pack.

In our bodies groups of stem cells are able to move in specific ways to form different organs and tissues when exposed to the right environment. Unfortunately, we are still trying to learn what “the right environment” is for different organs.

In a news release, McDevitt, the senior author of the paper published in the journal Stem Cell Reports, says this method of observing cells may help us better understand that.

“If I wanted to make a new human heart right now, I know what types of cells are needed, and I know how to grow them independently in dishes. But we really don’t know how to get those cells to come together to form something as complex as a heart. To accomplish that, we need more insights into how cells work cooperatively to arrange themselves.”

Normally scientists watch cells by tagging them with a fluorescent marker so they can see them under a microscope. But this is slow, painstaking work and not particularly accurate. This new method used a series of what are called “neural networks”, which are artificial intelligence (AI) programs that can detect patterns in the movements of the cells. When combined together the networks proved to be able to track the movement of 95 percent of the cells. Humans by comparison can only manage up to 90 percent. But the nets were not only sharper, they were also faster, much faster, some 500 times faster.

This enhanced ability to watch the cells showed that instead of being static most of the time, as had previously been thought, they were actually on the move a lot of the time. They would move around for 15 minutes and then take a breather for ten minutes (time for the stem cell equivalent of a cup of tea perhaps).  

Some cells moved around a lot in one direction, while others just seemed to shuffle around in the same area. Some cells even seemed to act as “leaders” while other cells appeared to be “followers” and shuffle along behind them.

None of this would have been visible without the power of the AI networks and McDevitt says being able to tap into this could help researchers better understand how to use these complex movements.

“This technique gives us a much more comprehensive view of how cells behave, how they work cooperatively, and how they come together in physical space to form complex organs.

Follow the Leader is not just a kids’ game anymore. Now it’s a scientific undertaking.

Persistence pays off in search for clue to heart defects

A team of scientists led by Benoit Bruneau (left), including Irfan Kathiriya (center) and Kavitha Rao (right), make inroads into understanding what genes are improperly deployed in some cases of congenital heart disease.  Photo courtesy Gladstone Institute

For more than 20 years Dr. Benoit Bruneau has been trying to identify the causes of congenital heart disease, the most common form of birth defect in the U.S. It turns out that it’s not one cause, but many.

Congenital heart disease covers a broad range of defects, some relatively minor and others life-threatening and even fatal. It’s been known that a mutation in a gene called TBX5 is responsible for some of these defects, so, in a CIRM-funded study ($1.56 million), Bruneau zeroed in on this mutation to see if it could help provide some answers.

In the past Bruneau, the director of the Gladstone Institute of Cardiovascular Disease, had worked with a mouse model of TBX5, but this time he used human induced pluripotent stem cells (iPSCs). These are cells that can be manipulated in the lab to become any kind of cell in the human body. In a news release Bruneau says this was an important step forward.

“This is really the first time we’ve been able to study this genetic mutation in a human context. The mouse heart is a good proxy for the human heart, but it’s not exactly the same, so it’s important to be able to carry out these experiments in human cells.”

The team took some iPSCs, changed them into heart cells, and used a gene editing tool called CRISPR-Cas9 to create the kinds of mutations in TBX5 that are seen in people with congenital heart disease. What they found was some genes were affected a lot, some not so much. Which is what you might expect in a condition that causes so many different forms of problems.

“It makes sense that some are more affected than others, but this is the first experimental data in human cells to show that diversity,” says Bruneau.

But they didn’t stop there. Oh no. Then they did a deep dive analysis to understand how the different ways that different cells were impacted related to each other. They found some cells were directly affected by the TBX5 mutation but others were indirectly affected.

The study doesn’t point to a simple way of treating congenital heart disease but Bruneau says it does give us a much better understanding of what’s going wrong, and perhaps will give us better ideas on how to stop that.

“Our new data reveal that the genes are really all part of one network—complex but singular—which needs to stay balanced during heart development. That means if we can figure out a balancing factor that keeps this network functioning, we might be able to help prevent congenital heart defects.”

The study is published in the journal Developmental Cell.

Gladstone scientists respond to coronavirus pandemic

In these uncertain times, we often look to our top scientists for answers as well as potential solutions. But where does one begin to try and solve a problem of this magnitude? The first logical step is building on the supplies currently available, the work already accomplished, and the knowledge acquired.

This is the approach that the Gladstone Institutes in San Francisco is taking. Various scientists at this institution have shifted their current operations towards helping with the current coronavirus pandemic. These efforts have focused on helping with diagnostics, treatment, and prevention of COVID-19.

Diagnostics

Dr. Jennifer Doudna and Dr. Melanie Ott are collaborating in order to develop an effective method to rapidly diagnose those with COVID-19. Dr. Doudna’s work has focused on CRISPR technology, which we have talked about in detail in a previous blog post, while Dr. Ott has focused on studying viruses. By combining their expertises, these two scientists hope to develop a diagnostic tool capable of delivering rapid results and usable in areas such as airports, ports of entry, and remote communities.

Treatment

Dr. Nevan Krogan has discovered all of the human host cell proteins that COVID-19 interacts with to hijack the cell’s machinery. These proteins serve as new targets for potential drug therapies.

Since the high fatality rate of the virus is driven by lung and heart failure, Dr. Ott, Dr. Bruce Conklin, and Dr. Todd McDevitt will test effects of the virus and potential drug therapies in human lung organoids and human heart cells, both developed from human stem cells.

Dr. Warner Greene, who also focuses on the study of viruses, is screening a variety of FDA-approved drugs to identify those that could be rapidly repurposed as a treatment for COVID-19 patients or even as a preventive for high risk-groups.

Prevention

Dr. Leor Weinberger has developed a new approach to fight the spread of viruses. It is called therapeutic interfering particles (TIPs) and could be an alternative to a vaccine. TIPs are defective virus fragments that mimic the virus but are not able to replicate. They combat the virus by hijacking the cell machinery to transform virus-infected cells into factories that produce TIPS, amplifying the effect of TIPs in stopping the spread of virus. TIPs targeting COVID-19 would transmit along the same paths as the virus itself, and thus provide protection to even the most vulnerable populations.

You can read more about these groundbreaking projects in the news release linked here.

When Google turns on you, you know you are in trouble

For years CIRM and others in the stem cell community (hello Paul Knoepfler) have been warning people about the dangers of going to clinics offering unproven and unapproved stem cell therapies. Recently the drum beat of people and organizations coming out in support of that stand has grown louder and louder. Mainstream media – TV and print – have run articles about these predatory clinics. And now, Google has joined those ranks, announcing it will restrict ads promoting these clinics.

“We regularly review and revise our advertising policies. Today, we’re announcing a new Healthcare and medicines policy to prohibit advertising for unproven or experimental medical techniques such as most stem cell therapy, cellular (non-stem) therapy, and gene therapy.”

Deepak Srivastava: Photo courtesy Gladstone Institutes

The president of the International Society for Stem Cell Research (ISSCR) Dr. Deepak Srivastava quickly issued a statement of support, saying:

“Google’s new policy banning advertising for speculative medicines is a much-needed and welcome step to curb the marketing of unscrupulous medical products such as unproven stem cell therapies. While stem cells have great potential to help us understand and treat a wide range of diseases, most stem cell interventions remain experimental and should only be offered to patients through well-regulated clinical trials. The premature marketing and commercialization of unproven stem cell products threatens public health, their confidence in biomedical research, and undermines the development of legitimate new therapies.”

Speaking of Deepak – we can use first names here because we are not only great admirers of him as a physician but also as a researcher, which is why we have funded some of his research – he has just published a wonderfully well written article criticizing these predatory clinics.

The article – in Scientific American – is titled “Don’t Believe Everything You Hear About Stem Cells” and rather than paraphrase his prose, I think it best if you read it yourself. So, here it is.

Enjoy.

Don’t Believe Everything You Hear about Stem Cells

The science is progressing rapidly,but bad actors have co-opted stem cells’ hope and promise by preying on unsuspecting patients and their families

Stem cell science is moving forward rapidly, with potential therapies to treat intractable human diseases on the horizon.Clinical trials are now underway to test the safety and effectiveness of stem cell–based treatments for blindness,spinal cord injury,heart disease,Parkinson’s disease, and more,some with early positive results.A sense of urgency drives the scientific community, and there is tremendous hope to finally cure diseases that, to date, have had no treatment.


But don’t believe everything you hear about stem cells. Advertisements and pseudo news articles promote stem cell treatments for everything from Alzheimer’s disease,autism and ALS, to cerebral palsy and other diseases.The claims simply aren’t true–they’re propagated by people wanting to make money off of a desperate and unsuspecting or unknowing public.Patients and their families can be misled by deceptive marketing from unqualified physicians who often don’t have appropriate medical credentials and offer no scientific evidence of their claims.In many cases, the cells being utilized are not even true stem cells.

Advertisements for stem cell treatments are showing up everywhere, with too-good-to-be-true claims and often a testimonial or two meant to suggest legitimacy or efficacy.Beware of the following:

    •       Claims that stem cell treatments can treat a wide range of diseases using a singular stem cell type. This is unlikely to be true.

    •       Claims that stem cells taken from one area of the body can be used to treat another, unrelated area of the body. This is also unlikely to be true.     •       Patient testimonials used to validate a particular treatment, with no scientific evidence. This is a red flag.

    •       Claims that evidence doesn’t yet exist because the clinic is running a patient-funded trial. This is a red flag; clinical trials rarely require payment for experimental treatment.

    •       Claims that the trial is listed on ClinicalTrials.gov and is therefore NIH-approved. This may not be true. The Web site is simply a listing; not all are legitimate trials.

    •       The bottom line: Does the treatment sound too good to be true? If so, it probably is. Look for concrete evidence that the treatment works and is safe.

Hundreds of clinics offer costly, unapproved and unproven stem cell interventions, and patients may suffer physical and financial harm as a result.A Multi-Pronged Approach to Deal with Bad Actors 

The International Society for Stem Cell Research (ISSCR)has long been concerned that bad actors have co-opted the hope and promise of stem cell science to prey on unsuspecting patients and their families.

We read with sadness and disappointment the many stories of people trying unproven therapies and being harmed, including going blind from injections into the eyes or suffering from a spinal tumor after an injection of stem cells.Patients left financially strapped, with no physical improvement in their condition and no way to reclaim their losses, are an underreported and underappreciated aspect of these treatments.

Since late 2017, the Food and Drug Administration has stepped up its regulatory enforcement of stem cell therapies and provided a framework for regenerative medicine products that provides guidelines for work in this space.The agency has alerted many clinics and centers that they are not in compliance and has pledged to bring additional enforcement action if needed.

A Multi-Pronged Approach to Deal with Bad Actors  The International Society for Stem Cell Research (ISSCR) has long been concerned that bad actors have co-opted the hope and promise of stem cell science to prey on unsuspecting patients and their families.

We read with sadness and disappointment the many stories of people trying unproven therapies and being harmed, including going blind from injections into the eyesor suffering from a spinal tumor after an injection of stem cells.Patients left financially strapped, with no physical improvement in their condition and no way to reclaim their losses, are an underreported and underappreciated aspect of these treatments.

Since late 2017, the Food and Drug Administration has stepped up its regulatory enforcement of stem cell therapies and provided a framework for regenerative medicine products that provides guidelines for work in this space.The agency has alerted many clinics and centers that they are not in compliance and has pledged to bring additional enforcement action if needed.

In recent weeks, a federal judge granted the FDA a permanent injunction against U.S. Stem Cell, Inc. and U.S. Stem Cell Clinic, LLC for adulterating and misbranding its cellular products and operating outside of regulatory authority.We hope this will send a strong message to other clinics misleading patients with unapproved and potentially harmful cell-based products.

The Federal Trade Commission has also helped by identifying and curtailing unsubstantiated medical claims in advertising by several clinics. Late in 2018 the FTC won a $3.3-million judgment against two California-based clinics for deceptive health claims. The Federal Trade Commission has also helped by identifying and curtailing unsubstantiated medical claims in advertising by several clinics. Late in 2018 the FTC won a $3.3-million judgment against two California-based clinics for deceptive health claims.

These and other actions are needed to stem the tide of clinics offering unproved therapies and the people who manage and operate them.

Improving Public Awareness

We’re hopeful that the FDA will help improve public awareness of these issues and curb the abuses on ClinicalTrials.gov,a government-run Web site being misused by rogue clinics looking to legitimize their treatments. They list pay-to-participate clinical trials on the site, often without developing, registering or administering a real clinical trial.

The ISSCR Web site A Closer Look at Stem Cellsincludes patient-focused information about stem cells,with information written and vetted by stem cell scientists.The site includes how and where to report adverse events and false marketing claims by stem cell clinics.I encourage you to visit and learn about what is known and unknown about stem cells and their potential for biomedicine.The views expressed are those of the author(s) and are not necessarily those of Scientific American.

How stem cells know the right way to make a heart . And what goes wrong when they don’t

Gladstone scientists Deepak Srivastava (left), Yvanka De Soysa (center), and Casey Gifford (right) publish a complete catalog of the cells involved in heart development.

The invention of GPS navigation systems has made finding your way around so much easier, providing simple instructions on how to get from point A to point B. Now, a new study shows that our bodies have their own internal navigation system that helps stem cells know where to go, and when, in order to build a human heart. And the study also shows what can go wrong when even a few cells fail to follow directions.

In this CIRM-supported study, a team of researchers at the Gladstone Institutes in San Francisco, used a new technique called single cell RNA sequencing to study what happens in a developing heart. Single cell RNA sequencing basically takes a snapshot photo of all the gene activity in a single cell at one precise moment. Using this the researchers were able to follow the activity of tens of thousands of cells as a human heart was being formed.

In a story in Science and Research Technology News, Casey Gifford, a senior author on the study, said this approach helps pinpoint genetic variants that might be causing problems.

“This sequencing technique allowed us to see all the different types of cells present at various stages of heart development and helped us identify which genes are activated and suppressed along the way. We were not only able to uncover the existence of unknown cell types, but we also gained a better understanding of the function and behavior of individual cells—information we could never access before.”

Then they partnered with a team at Luxembourg Centre for Systems Biomedicine (LCSB) of the University of Luxembourg which ran a computational analysis to identify which genes were involved in creating different cell types. This highlighted one specific gene, called Hand2, that controls the activity of thousands of other genes. They found that a lack of Hand2 in mice led to an inability to form one of the heart’s chambers, which in turn led to impaired blood flow to the lungs. The embryo was creating the cells needed to form the chamber, but not a critical pathway that would allow those cells to get where they were needed when they were needed.

Gifford says this has given us a deeper insight into how cells are formed, knowledge we didn’t have before.

“Single-cell technologies can inform us about how organs form in ways we couldn’t understand before and can provide the underlying cause of disease associated with genetic variations. We revealed subtle differences in very, very small subsets of cells that actually have catastrophic consequences and could easily have been overlooked in the past. This is the first step toward devising new therapies.”

These therapies are needed to help treat congenital heart defects, which are the most common and deadly birth defects. There are more than 2.5 million Americans with these defects. Deepak Srivastava, President of Gladstone and the leader of the study, said the knowledge gained in this study could help developed strategies to help address that.

“We’re beginning to see the long-term consequences in adults, and right now, we don’t really have any way to treat them. My hope is that if we can understand the genetic causes and the cell types affected, we could potentially intervene soon after birth to prevent the worsening of their state over time.

The study is published in the journal Nature.