Study shows that COVID-19 vaccine is safe and effective in people with cancer

As we have seen in the US and all around the world, SARS-CoV-2, the virus that causes COVID-19, can cause severe complications and even death in many patients. In the early days of the pandemic, CIRM authorized $5 million in emergency funding for projects targeting the virus. To date CIRM has funded 20 projects related to COVID-19 research, including three clinical studies.

Luckily there have been several vaccines developed that are extremely effective at protecting individuals from the virus. These vaccines work by priming the body’s immune system to produce antibodies that are able to recognize and destroy SARS-CoV-2.

However, one question that remains is if patients with a weakened immune system, such as those receiving active cancer treatment, would be able to produce the antibodies after vaccination. Fortunately, a review of 200 patients with a wide spectrum of cancer diagnoses conducted by researchers at Montefiore Health System and Albert Einstein College of Medicine in the Bronx, NY, found that the COVID-19 vaccine is safe and effective in people with cancer.

The study looked at the rate of seroconversion, which indicates the presence of SARS-CoV-2 antibodies, in patients with solid tumors and blood cancers. The higher the rate of seroconversion, the more protection from COVID the patient has. The results showed that overall 94 percent of patients demonstrated seroconversion. Patients with solid tumors had a higher seroconversion rate compared to patients with blood cancers. Among patients with solid tumors 98 percent showed seroconversion while those with blood cancers showed a seroconversion rate of 85 percent.

The seroconversion rate also varied between those that received different cancer treatments. Those that received therapies for blood cancers that work by killing B cells (such as rituximab or CAR-T therapies) showed seroconversion rates of 70 percent. For those who had recently had bone marrow or stem cell transplants, the success rate was 74 percent. But the researchers stated that those rates were still much higher than expected.

In a news release, Amit Verma, M.B.B.S., senior co-author on the study, stresses the importance of cancer patients getting vaccinated.

“Vaccination among these populations have been lower, even though these groups were hardest hit by the pandemic. It’s important to stress how well these patient populations did with the vaccines.”

The full results of the study were published in Cancer Cell.

CIRM funding helps identify potential COVID-19 treatment

The steps of the virus growth cycle that can be targeted with therapies: The virus enters a host cell (1), the virus’s genetic instructions are released, taking over cellular machinery (2), the virus is replicated within the cell (3) and copies of the virus exit the cell in search of new host cells to infect (4). Drugs like berzosertib might disrupt steps 2 and 3.  Image credit: Marc Roseboro/California NanoSytems Institute at UCLA

During the global pandemic, many researchers have responded to the needs of patients severely afflicted with COVID-19 by repurposing existing therapies being developed to treat patients.  CIRM responded immediately to the pandemic and to researchers wanting to help by providing $5 million in emergency funding for COVID-19 related projects. 

One of these grants ($349,999), awarded to Dr. Vaithilingaraja Arumugaswami at UCLA, has aided a study that has singled out a compound that shows promise for treating SARS-CoV-2, the virus that causes COVID-19.

In the spirit of banding together to help patients severely affected by COVID-19, the project was a collaboration among scientists from UCLA and other universities in California, Delaware and Germany, as well as a German pharmaceutical company.

The compound is named berzosertib and is licensed by the company Merck KGaA in Darmstadt, Germany.  Prior to the pandemic, it was developed for potential use, in combination with chemotherapy, as a possible treatment for small-cell lung cancer, ovarian cancer, and other types of solid tumors.

The team screened 430 drugs from among the approximately 200,000 compounds in CNSI’s Molecular Screening Shared Resource libraries before zeroing in on berzosertib as the most promising candidate.  They limited their search to compounds that either had been approved, or are already in the process of being evaluated, for safety in humans.

In a press release from UCLA, Dr. Arumugawami explains the rationale behind screening a potential drug candidate.

“That way, the compounds have cleared the first regulatory hurdle and could be deployed for further clinical trials on COVID-19 faster than drugs that have not been tested in humans.”

The researchers, led by Dr. Arumugaswami and Dr. Robert Damoiseaux from UCLA, conducted a series of experiments using different cell types in lab dishes to look at how effective the compound was at blocking SARS-CoV-2 from replicating.  Unlike other approaches which attack the virus directly, targeting replication could help better address the ability of the virus to mutate. 

For this study, the team used cells from the kidney, heart and lungs, all of which are organs that the virus is known to attack. The researchers pretreated cells with berzosertib, exposed the cells to SARS-CoV-2, allowed 48 hours for infection to set in, and then evaluated the results.

The team found that the compound consistently stalled SARS-CoV-2 replication without damaging the cells. The scientists also tested the drug against SARS and MERS, both of which are other types of coronaviruses that triggered deadly outbreaks earlier in the 2000s. They found that it was effective in stopping the replication of those viruses as well.

In the same press release from UCLA, Dr. Damoiseaux expressed optimism for what these findings could mean as a potential treatment.

“This is a chance to actually find a drug that might be broader in spectrum, which could also help fight coronaviruses that are yet to come.”

The next steps for this research would be to explore the mechanism through which the compound blocks coronavirus replication.  Understanding this and conducting preclinical studies are both necessary before the compound could be tested in clinical trials for COVID-19.

The full results of this study were published in Cell Reports.

The study’s co-corresponding author is Ulrich Betz of Merck KGaA, Darmstadt, Germany; the company also provided partial funding and clinical-grade berzosertib for the research. Other co-authors are from UCLA, Cedars-Sinai Medical Center, UC Irvine, University of Delaware, the Leibniz Institute for Experimental Virology in Germany, Heidelberg University in Germany and Scripps Research Institute.

In addition to CIRM, the study was also funded by CNSI, the Broad Stem Cell Research Center, the David Geffen School of Medicine at UCLA, the National Eye Institute, and the Bill and Melinda Gates Foundation.

Scientists look at how the lung and brain respond differently to SARS-CoV-2 infection

UC San Diego School of Medicine researchers found approximately 10-fold higher SARS-CoV-2 infection (green) in lung organoids (left), compared to brain organoids (right). Image courtesy of UCSD Health

Since the start of the coronavirus pandemic early last year, scientists all over the world are still trying to better understand SARS-CoV-2, the virus that causes COVID-19. Although the more commonly known symptoms involve respiratory issues, there have been other long term problems observed in recovered patients. These consist of heart issues, fatigue, and neurological issues such as loss of taste and smell and “brain fog”.

To better understand this, Dr. Tariq Rana and a team of researchers at the UC San Diego School of Medicine are using stem cells to create lung and brain organoids to better understand how the virus interacts with the various organ systems and to better develop therapies that block infection. Organoids are 3D models made of cells that can be used to analyze certain features of the human organ being modeled. Although they are far from perfect replicas, they can be used to study physical structure and other characteristics. 

The team’s lung and brain organoids produced molecules ACE2 and TMPRSS2, which sit like doorknobs on the outer surfaces of cells. SARS-CoV-2 is able to use these doorknobs to enter cells and establish infection.

Dr. Rana and his team then developed a pseudovirus, a noninfectious version of SARS-CoV-2, and attached a fluorescent label, allowing them to measure how effectively the virus binds in human lung and brain organoids as well as to evaluate the cells’ response. The team was surprised to see an approximately 10-fold higher SARS-CoV-2 infection in lung organoids compared to brain organoids. Additionally, treatment with TMPRSS2 inhibitors reduced infection levels in both organoids.

Besides differences in infection levels, the lung and brain organoids also differed in their responses to the virus. Infected lung organoids pumped out molecules intended to summon help from the immune system while infected brain organoids upped their production of molecules that plays a fundamental role in pathogen recognition and activation of the body’s own immune defenses.

In a news release from UC San Diego Health, Dr. Rana elaborates on the results of his study.

“We’re finding that SARS-CoV-2 doesn’t infect the entire body in the same way. In different cell types, the virus triggers the expression of different genes, and we see different outcomes.”

The next steps for Rana and his team is to develop SARS-CoV-2 inhibitors and test out how well they work in organoid models derived from people of a variety of racial and ethnic backgrounds that represent California’s diverse population. To carry out this research, CIRM awarded Dr. Rana a grant of $250,000, which is part of the $5 million in emergency funding for COVID-19 research that CIRM authorized at the beginning of the pandemic.

The full results of this study can be found in Stem Cell Reports.

CIRM funded researchers discover link between Alzheimer’s gene and COVID-19

Dr. Yanhong Shi (left) and Dr. Vaithilingaraja Arumugaswami (right)

All this month we are using our blog and social media to highlight a new chapter in CIRM’s life, thanks to the voters approving Proposition 14. We are looking back at what we have done since we were created in 2004, and also looking forward to the future. Today we focus on groundbreaking CIRM funded research related to COVID-19 that was recently published.

It’s been almost a year since the world started hearing about SARS-CoV-2, the virus that causes COVID-19.  In our minds, the pandemic has felt like an eternity, but scientists are still discovering new things about how the virus works and if genetics might play a role in the severity of the virus.  One population study found that people who have ApoE4, a gene type that has been found to increase the risk of developing Alzheimer’s, had higher rates of severe COVID-19 and hospitalizations.

It is this interesting observation that led to important findings of a study funded by two CIRM awards ($7.4M grant and $250K grant) and conducted by Dr. Yanhong Shi at City of Hope and co-led by Dr. Vaithilingaraja Arumugaswami, a member of the UCLA Broad Stem Cell Research Center.  The team found that the same gene that increases the risk for Alzheimer’s disease can increase the susceptibility and severity of COVID-19.

At the beginning of the study, the team was interested in the connection between SARS-CoV-2 and its effect on the brain.  Due to the fact that patients typically lose their sense of taste and smell, the team theorized that there was an underlying neurological effect of the virus.  

The team first created neurons and astrocytes.  Neurons are cells that function as the basic working unit of the brain and astrocytes provide support to them.  The neurons and astrocytes were generated from induced pluripotent stem cells (iPSCs), which are a kind of stem cell that can become virtually any type of cell and can be created by “reprogramming” the skin cells of patients.  The newly created neurons and astrocytes were then infected with SARS-CoV-2 and it was found that they were susceptible to infection.

Next, the team used iPSCs to create brain organoids, which are 3D models that mimic certain features of the human brain.  They were able to create two different organoid models: one that contained astrocytes and one without them.  They infected both brain organoid types with the virus and discovered that those with astrocytes boosted SARS-CoV-2 infection in the brain model. 

The team then decided to further study the effects of ApoE4 on susceptibility to SARS-CoV-2.  They did this by generating neurons from iPSCs “reprogrammed” from the cells of an Alzheimer’s patient.  Because the iPSCs were derived from an Alzheimer’s patient, they contained ApoE4.  Using gene editing, the team modified some of the ApoE4 iPSCs created so that they contained ApoE3, which is a gene type considered neutral.  The ApoE3 and ApoE4 iPSCs were then used to generate neurons and astrocytes.

The results were astounding.  The ApoE4 neurons and astrocytes both showed a higher susceptibility to SARS-CoV-2 infection in comparison to the ApoE3 neurons and astrocytes.  Moreover, while the virus caused damage to both ApoE3 and ApoE4 neurons, it appeared to have a slightly more severe effect on ApoE4 neurons and a much more severe effect on ApoE4 astrocytes compared to ApoE3 neurons and astrocytes. 

“Our study provides a causal link between the Alzheimer’s disease risk factor ApoE4 and COVID-19 and explains why some (e.g. ApoE4 carriers) but not all COVID-19 patients exhibit neurological manifestations” says Dr. Shi. “Understanding how risk factors for neurodegenerative diseases impact COVID-19 susceptibility and severity will help us to better cope with COVID-19 and its potential long-term effects in different patient populations.”

In the last part of the study, the researchers tested to see if the antiviral drug remdesivir inhibits virus infection in neurons and astrocytes.  They discovered that the drug was able to successfully reduce the viral level in astrocytes and prevent cell death.  For neurons, it was able to rescue them from steadily losing their function and even dying. 

The team says that the next steps to build on their findings is to continue studying the effects of the virus and better understand the role of ApoE4 in the brains of people who have COVID-19.  Many people that developed COVID-19 have recovered, but long-term neurological effects such as severe headaches are still being seen months after. 

“COVID-19 is a complex disease, and we are beginning to understand the risk factors involved in the manifestation of the severe form of the disease” says Dr. Arumugaswami.  “Our cell-based study provides possible explanation to why individuals with Alzheimer’s’ disease are at increased risk of developing COVID-19.”

The full results to this study were published in Cell Stem Cell.

Month of CIRM: Battling COVID-19

All this month we are using our blog and social media to highlight a new chapter in CIRM’s life, thanks to the people of California approving Proposition 14. We are looking back at what we have done since we were created in 2004, and also looking forward to the future.

Dr. John Zaia, City of Hope stem cell researcher

The news that effective vaccines have been developed to help fight COVID-19 was a truly bright spot at the end of a very dark year. But it will be months, in some countries years, before we have enough vaccines to protect everyone. That’s why it’s so important to keep pushing for more effective ways to help people who get infected with the virus.

One of those ways is in a clinical study that CIRM is funding with City of Hope’s Dr. John Zaia. Dr. Zaia and his team, in partnership with the Translational Genomics Research Institute (TGen) in Flagstaff, Arizona, are using something called convalescent plasma to try and help people who have contracted the virus. Here’s the website they have created for the study.

Plasma is a part of our blood that carries proteins, called antibodies, that help defend our bodies against viral infections. When a patient recovers from COVID-19, their blood plasma contains antibodies against the virus. The hope is that those antibodies can now be used as a potential treatment for COVID-19 to help people who are newly infected. 

To carry out the study they are using clinical trial sites around California, including some of the CIRM Alpha Stem Cell Network clinics.

For the study to succeed they’ll first need people who have recovered from the virus to donate blood. That’s particularly appropriate in January because this is National Volunteer Blood Donor Month.

The team has three elements to their approach:

  • A rapid-response screening program to screen potential COVID-19 convalescent plasma donors, particularly in underserved communities.
  • A laboratory center that can analyze the anti-SARS-CoV-2 antibodies properties in COVID-19 convalescent plasma.
  • An analysis of the clinical course of the disease in COVID-19 patients to identify whether antibody properties correlate with clinical benefit of COVID-19 convalescent plasma.

There’s reason to believe this approach might work. A study published this week in the New England Journal of Medicine, found that blood plasma from people who have recovered from COVID-19 can help older adults and prevent them from getting seriously ill with the virus if they get the plasma within a few days of becoming infected.

We are used to thinking of blood donations as being used to help people after surgery or who have been in an accident. In this study the donations serve another purpose, but one that is no less important. The World Health Organization describes blood as “the most precious gift that anyone can give to another person — the gift of life. A decision to donate your blood can save a life, or even several if your blood is separated into its components — red cells, platelets and plasma.”

That plasma could help in developing more effective treatments against the virus. Because until we have enough vaccines for everyone, we are still going to need as much help as we can get in fighting COVID-19. The recent surge in cases throughout the US and Europe are a reminder that this virus is far from under control. We have already lost far too many people. So, if you have recently recovered from the virus, or know someone who has, consider donating blood to this study. It could prove to be a lifesaver.

For more information about the study and how you can be part of it, click here.

UCLA scientists discover how SARS-CoV-2 causes multiple organ failure in mice

Heart muscle cells in an uninfected mouse (left) and a mouse infected with SARS-CoV-2 (right) with mitochondria seen in pink. The disorganization of the cells and mitochondria in the image at right is associated with irregular heartbeat and death.
Image credit: UCLA Broad Stem Cell Center

As the worldwide coronavirus pandemic rages on, scientists are trying to better understand SARS-CoV-2, the virus that causes COVID-19, and the effects that it may have beyond those most commonly observed in the lungs. A CIRM-funded project at UCLA, co-led by Vaithilingaraja Arumugaswami, Ph.D. and Arjun Deb, M.D. discovered that SARS-CoV-2 can cause organ failure in the heart, kidney, spleen, and other vital organs of mice.

Mouse models are used to better understand the effects that a disease can have on humans. SARS-CoV-2 relies on a protein named ACE2 to infect humans. However, the virus doesn’t recognize the mouse version of the ACE2 protein, so healthy mice exposed to the SARS-CoV-2 virus don’t get sick.

To address this, past experiments by other research teams have genetically engineered mice to have the human version of the ACE2 protein in their lungs. These teams then infected the mice, through the nose, with the SARS-CoV-2 virus. Although this process led to viral infection in the mice and caused pneumonia, they don’t get as broad a range of other symptoms as humans do.

Previous research in humans has suggested that SARS-CoV-2 can circulate through the bloodstream to reach multiple organs. To evaluate this further, the UCLA researchers genetically engineered mice to have the human version of the ACE2 protein in the heart and other vital organs. They then infected half of the mice by injecting SARS-CoV-2 into their bloodstreams and compared them to mice that were not infected. The UCLA team tracked overall health and analyzed how levels of certain genes and proteins in the mice changed.

Within seven days, all of the mice infected with the virus had stopped eating, were completely inactive, and had lost an average of about 20% of their body weight. The genetically engineered mice that had not been infected with the virus did not lose a significant amount of weight. Furthermore, the infected mice had altered levels of immune cells, swelling of the heart tissue, and deterioration of the spleen. All of these are symptoms that have been observed in people who are critically ill with COVID-19.

What’s even more surprising is that the UCLA team also found that genes that help cells generate energy were shut off in the heart, kidney, spleen and lungs of the infected mice. The study also revealed that some changes were long-lasting throughout the organs in mice with SARS-CoV-2. Not only were genes turned off in some cells, the virus made epigenetic changes, which are chemical alterations to the structure of DNA that can cause more lasting effects. This might help explain why some people that have contracted COVID-19 have symptoms for weeks or months after they no longer have traces of the virus in their body.

In a UCLA press release, Dr. Deb discusses the importance and significance of their findings.

“This mouse model is a really powerful tool for studying SARS-CoV-2 in a living system. Understanding how this virus can hijack our cells might eventually lead to new ways to prevent or treat the organ failure that can accompany COVID-19 in humans.”

The full results of this study were published in JCI Insight.

CIRM-funded study shows how cigarette smoke can worsen COVID-19 infection in the airways

Microscopic images of human stem cell–derived airway tissue models with cell nuclei (blue) and SARS-CoV-2 virus infected cells (green); tissue exposed to cigarette smoke (right) had 2 to 3 times more infected cells than non-exposed tissue (left).
Image Credit: UCLA Broad Stem Cell Research Center/Cell Stem Cell

In the middle of a pandemic, stress can run really high and you might be tempted to light up a cigarette to decompress from the world around you. However, a CIRM-funded study revealed that you might want to think twice before lighting up.

It is already known that cigarette smoke is one of the most common causes of lung diseases, including lung cancer, but Dr. Brigitte Gomperts and Vaithilingaraja Arumugaswami at UCLA have pinpointed how smoking cigarettes may worsen infection by SARS-CoV-2, the virus that causes COVID-19, in the airways of the lungs.

The team used airway stem cells from the lungs of healthy non-smoking donors to create a tissue model that replicates the way that airways behave and function in humans. The researchers then exposed these newly created airways to cigarette smoke to mimic the effects of smoking.

Next, the team infected the airway tissue exposed with cigarette smoke with SARS-CoV-2 and also infected tissue not exposed to cigarette smoke. In the tissue model exposed to smoke, the researchers saw between two and three times more infected cells.

The UCLA team determined that smoking resulted in more severe SARS-CoV-2 infection. This was due to the smoke blocking the activity of immune system messenger proteins called interferons, which play an important role in the body’s early immune response. They trigger infected cells to produce proteins to attack the virus, summon additional support from the immune system, and alert uninfected cells to prepare to fight the virus. Cigarette smoke is known to reduce the interferon response in the airways.

In a UCLA news release, Dr. Gomperts explains the results with a simple analogy.

“If you think of the airways like the high walls that protect a castle, smoking cigarettes is like creating holes in these walls. Smoking reduces the natural defenses and that allows the virus to set in.” 

The hope is that these findings will help researchers better understand COVID-19 risks for smokers and could inform the development of new therapeutic strategies to help reduce smokers’ chances of developing severe disease.


One shot, two benefits!

Doctor preparing an influenza vaccine for a patient.

To try and boost sales during the pandemic many businesses are offering two-for-one deals; buy one product get another free. Well, that might also be the case with a flu shot; get one jab and get protection from two viruses.

A new study offers an intriguing – though not yet certain – suggestion that getting a flu shot could not only reduce your risk of getting the flu, but also help reduce your risk of contracting the coronavirus. If it’s true it would be a wonderful tool for health professionals hoping to head of a twindemic of flu and COVID-19 this winter. It would also be a pretty sweet deal for the rest of us.

Researchers at Radboud University Medical Center in the Netherlands looked through their hospital’s database and compared people who got a flu shot during the previous year with people who didn’t. They found that people who got the vaccine were 39 percent less likely to have tested positive for the coronavirus than people who didn’t get the vaccine.

Now, there are a bunch of caveats about this study (published in the preprint journal MedRxiv) one of which is that it wasn’t peer reviewed. Another is that people who get flu shots might just be more health conscious than people who don’t, which means they might also be more aware of the need to wear a mask, social distance, wash their hands etc.

But that doesn’t mean this study is wrong. Two recent studies (in the journal Vaccines and the Journal of Medical Virology) also found similar findings, that people over the age of 65 who got a flu shot had a lower risk of getting COVID-19. That’s particularly important for that age group as they are the ones most likely to experience life-threatening complications from COVID-19.

But what could explain getting a two-fer from one vaccine? Well, there’s a growing body of research that points to something called “trained innate immunity”. Our bodies have two different kinds of immune system, adaptive and innate. Vaccines activate the adaptive system, causing it to develop antibodies to attack and kill a virus. But there’s also evidence these same vaccines could trigger our innate immune system to help fight off infections. So, a flu vaccine could boost your adaptive immunity against the flu, but also kick in the innate immunity against the coronavirus.

In an article in Scientific American, Ellen Foxman, an immunobiologist and clinical pathologist at the Yale School of Medicine, says that might be the case here: “There is evidence from the literature that trained immunity does exist and can offer broad protection, in unexpected ways, against other pathogens besides what the vaccine was designed against.”

The researchers in the Netherlands wanted to see if there was any evidence that what they saw in their hospital had any basis in fact. So, they devised a simple experiment. They took blood cells from healthy individuals and exposed some of the cells to the flu vaccine. After six days they exposed all the cells to the SARS-CoV-2, the virus that causes COVID-19.

Compared to the untreated cells, the cells that had been exposed to the flu vaccine produced more virus-fighting immune molecules called cytokines. These can attack the virus and help protect people early on, resulting in a milder, less dangerous infection.

All in all it’s encouraging evidence that a flu shot might help protect you against the coronavirus. And at the very least it will reduce your risk of the flu, and if there’s one thing you definitely don’t want this year it’s having to battle two life-threatening viruses at the same time.

‘Mini lung’ model shows scientists early stages of new coronavirus infection

Representative image of three-dimensional human lung alveolar organoid showing alveolar stem cell marker, HTII-280 (red) and SARS-CoV-2 entry protein, ACE2 (green)
Image Credit: Jeonghwan Youk, Taewoo Kim, and Seon Pyo Hong

The development of organoid modeling has significantly expanded our understanding of human organs and the diseases that can affect them. For those unfamiliar with the term, an organoid is a miniaturized, simplified version of an organ produced that is also three dimensional.

Recently, scientists from the University of Cambridge and the Korea Advanced Institute Science and Technology (KAIST) were able to develop ‘mini lungs’ from donated tissue and use them to uncover the mechanisms behind the new coronavirus infection and the early immune response in the lungs.

SARS-CoV-2, the name of the coronavirus that causes COVID-19, first appears in the alveoli, which are tiny air sacs in the lungs that take up the oxygen we breathe and exchange it with carbon dioxide.

To better understand how SARS-CoV-2 infects the lungs and causes COVID-19, the team used donated tissue to extract a specific type of lung cell. They then reprogrammed these cells to an earlier stem cell-like state and used them to grow the lung organoids.

The team then infected the ‘mini lungs’ with a strain of SARS-CoV-2 taken from a patient in South Korea who was diagnosed with COVID-19 after traveling to Wuhan, China.

Within the newly infected lung organoids, the team observed that the virus began to replicate rapidly, reaching full cellular infection in just six hours. Replication allows the virus to spread the infection throughout the body to other cells and tissue. The infected cells also began to produce interferons, which are proteins that act as warning signals to healthy cells, telling them to activate their antiviral defenses. After two days, the interferons triggered an immune response and the cells started fighting back against infection. Two and a half days after infection, some of the alveolar cells began to disintegrate, leading to cell death and damage to the lung tissue.

In a news release, Dr. Joo-Hyeon Lee, co-senior author of this study, elaborates on how he hopes this study can help more vulnerable sections of the population.


The complete study was published in Cell Stem Cell.

CIRM has funded two discovery stage research projects that use lung organoids to look at potential treatments for COVID-19. One is being conducted by Dr. Brigitte Gomperts at UCLA and the other by Dr. Evan Snyder at the Sanford Burnham Prebys Medical Discovery Institute.

An Atlas of the Human Heart that May Guide Development of New Therapies

By Lisa Kadyk, PhD. CIRM Senior Science Officer

Illustration of a man’s heart – Courtesy Science Photo

I love maps; I still have auto club maps of various parts of the country in my car.  But, to tell the truth, those maps just don’t have as much information as I can get by typing in an address on my cell phone.  Technological advances in global positioning systems, cellular service, data gathering and storage, etc. have made my beloved paper maps a bit of a relic.  

Similarly, technological advances have enabled scientists to begin making maps of human tissues and organs at a level of detail that was previously unimaginable.  Hundreds of thousands of single cells can be profiled in parallel, examining expression of RNA and proteins.  These data, in combination with new three-dimensional spatial analysis techniques and sophisticated computational algorithms, allow high resolution mapping of all the cells in a given tissue or organ.

Given these new capabilities, an international “Human Cell Atlas Consortium” published a white paper in 2017 outlining plans and strategies to build comprehensive reference maps of all human cells, organ by organ.  The intent of building such an atlas is to give a much better understanding of the biology and physiology of normal human tissues, as well as to give new insights into the nature of diseases affecting those tissues and to point the way to developing new therapies. 

One example of this new breed of cartography was published September 24 in the journal Nature, in a paper called simply “Cells of the Human Heart”.   This tour-de-force effort was led by scientists from Harvard Medical School, the Wellcome Sanger Institute, the Max Delbruck Center for Molecular Medicine in Berlin and Imperial College, London.  These teams and their collaborators analyzed about 500,000 cells from six different regions of the healthy adult human heart, using post-mortem organs from 14 donors.  They examined RNA and protein expression and mapped the distribution of different types of cells in each region of the heart.  In addition, they made comparisons of male and female hearts, and identified cells expressing genes known to be associated with different types of heart disease.  

One of the take-home messages from this study is that there is a lot of cellular complexity in the heart – with 11 major cell types (examples include atrial and ventricular cardiomyocytes, fibroblasts and smooth muscle cells), as well as multiple subpopulations within each of those types.  Also notable is the different distribution of cells between the atria (which are at the top of the heart and receive the blood) and ventricles (which are on the bottom of the heart and pump blood out): on average, close to half of the cells in the ventricles are cardiomyocytes, whereas only a third of the cells in the atria are cardiomyocytes.  Finally, there is a significantly higher percentage of cardiomyocytes in the ventricles of women (56%) than in the ventricles of men (47%).    The authors speculate that this latter difference might explain the higher volume of blood pumped per beat in women and lower rates of cardiovascular disease.  

The authors gave a few examples of how their data can be used for a better understanding of heart disease.  For example, they identified a specific subpopulation of cardiomyocytes that expresses genes associated with atrial fibrillation, suggesting that the defect may be associated with those cells.   Similarly, they found that a specific neuronal cell type expresses genes that are associated with a particular ventricular dysfunction associated with heart failure.    In addition, the authors identified which cells in the heart express the highest levels of the SARS-CoV-2 receptor, ACE2, including pericytes, fibroblasts and cardiomyocytes.  

Now that these data are accessible for exploration at, I have no doubt that many scientific explorers will begin to navigate to a more complete understanding of both the healthy and diseased heart, and ultimately to new treatments for heart disease.