The world of stem cell research lost a good friend this weekend. Eli Broad, a generous supporter of science, education and the arts, passed away at the age of 87.
Eli came from humble origins, born in the Bronx to an immigrant father who worked as a house painter and a mother who was a seamstress. He went to Michigan State University, working a number of jobs to pay his way, including selling women’s shoes, working as a door-to-door salesman for garbage disposal units, and delivering rolls of film to be developed. He graduated in three years and then became the youngest person ever to pass the CPA exam in Michigan.
He started out as an accountant but quickly switched to housing and development and was a millionaire by the time he was 30. As his wealth grew so did his interest in using that money to support causes dear to him and his wife Edythe.
With the passage of Proposition 71 in 2004 Broad put up money to help create the Broad Stem Cell Centers at UCLA, UC San Francisco and the University of Southern California. Those three institutions became powerhouses in stem cell research and the work they do is a lasting legacy to the generosity of the Broads.
“Science has lost one of its greatest philanthropic supporters,” says Jonathan Thomas, PhD, JD, Chair of the CIRM Board. ” Eli and Edye Broad set the table for decades of transformative work in stem cell and gene therapy through their enthusiastic support for Proposition 71 and funding at a critical time in the early days of regenerative medicine. Their recent additional generous contributions to USC, UCLA and UCSF helped to further advance that work. Eli and Edye understood the critical role of science in making the world a better place. Through these gifts and their enabling support of the Broad Institute with Harvard and MIT, they have left a lasting legacy in the advancement of medicine that cannot be overstated.”
“As a businessman Eli saw around corners, as a philanthropist he saw the problems in the world and tried to fix them, as a citizen he saw the possibility in our shared community, and as a husband, father, mentor and friend he saw the potential in each of us.”
The University of California, San Francisco (UCSF), in collaboration with UC Berkeley (UCB) and UC Los Angeles (UCLA), have been given permission by the US Food and Drug Administration (FDA) to launch a first-in-human clinical trial using CRISPR technology as a gene-editing technique to cure Sickle Cell Disease.
This research has been funded by CIRM from the early stages and, in a co-funding partnership with theNational Heart, Lung, and Blood Institute under the Cure Sickle Cell initiatve, CIRM supported the work that allowed this program to gain FDA permission to proceed into clinical trials.
Sickle Cell Disease is a blood disorder that affects around 100,000 people, mostly Black and Latinx people in the US. It is caused by a single genetic mutation that results in the production of “sickle” shaped red blood cells. Normal red blood cells are round and smooth and flow easily through blood vessels. But the sickle-shaped ones are rigid and brittle and clump together, clogging vessels and causing painful crisis episodes, recurrent hospitalization, multi-organ damage and mini-strokes.
The three UC’s have combined their respective expertise to bring this program forward.
The CRISPR-Cas9 technology was developed by UC Berkeley’s Nobel laureate Jennifer Doudna, PhD. UCLA is a collaborating site, with expertise in genetic analysis and cell manufacturing and UCSF Benioff Children’s Hospital Oakland is the lead clinical center, leveraging its renowned expertise in cord blood and marrow transplantation and in gene therapy for sickle cell disease.
The approach involves retrieving blood stem cells from the patient and, using a technique involving electrical pulses, these cells are treated to correct the mutation using CRISPR technology. The corrected cells will then be transplanted back into the patient.
In a news release, UCSF’s Dr. Mark Walters, the principal investigator of the project, says using this new gene-editing approach could be a game-changer. “This therapy has the potential to transform sickle cell disease care by producing an accessible, curative treatment that is safer than the current therapy of stem cell transplant from a healthy bone marrow donor. If this is successfully applied in young patients, it has the potential to prevent irreversible complications of the disease. Based on our experience with bone marrow transplants, we predict that correcting 20% of the genes should be sufficient to out-compete the native sickle cells and have a strong clinical benefit.”
Dr. Maria T. Millan, President & CEO of CIRM, said this collaborative approach can be a model for tackling other diseases. “When we entered into our partnership with the NHLBI we hoped that combining our resources and expertise could accelerate the development of cell and gene therapies for SCD. And now to see these three UC institutions collaborating on bringing this therapy to patients is truly exciting and highlights how working together we can achieve far more than just operating individually.”
The 4-year study will include six adults and three adolescents with severe sickle cell disease. It is planned to begin this summer in Oakland and Los Angeles.
The three UCs combined to produce a video to accompany news about the trial. Here it is:
Last November Marissa Cors, a patient advocate in the fight against Sickle Cell Disease (SCD), told the Stem Cellar “A stem cell cure will end generations of guilt, suffering, pain and early death. It will give SCD families relief from the financial, emotional and spiritual burden of caring someone living with SCD. It will give all of us an opportunity to have a normal life. Go to school, go to work, live with confidence.” With each passing month it seems we are getting closer to that day.
CIRM is funding four clinical trials targeting SCD and another project we are supporting has just been given the green light by the Food and Drug Administration to start a clinical trial. Clearly progress is being made.
Yesterday we got a chance to see that progress. We held a Zoom event featuring Marissa Cors and other key figures in the fight against SCD, CIRM Science Officer Dr. Ingrid Caras and Evie Junior. Evie is a pioneer in this struggle, having lived with sickle cell all his life but now hoping to live his life free of the disease. He is five months past a treatment that holds out the hope of eradicating the distorted blood cells that cause such devastation to people with the disease.
You can listen to his story, and hear about the other progress being made. Here’s a recording of the Zoom event.
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.
When people ask me what I do at CIRM I sometimes half-jokingly tell them that I’m the official translator: I take complex science and turn it into everyday English. That’s important. The taxpayers of California have a right to know how their money is being spent and how it might benefit them. But that message can be even more effective when it comes from the scientists themselves.
Recently we asked some of the scientists we are funding to do research into COVID-19 to record what’s called an “elevator pitch”. This is where they prepare an explanation of their work that is in ordinary English and is quite short, short enough to say it to someone as you ride in an elevator. Hence the name.
It sounds easy enough. But it’s not. When you are used to talking in the language of science day in and day out, suddenly switching codes to talk about your work in plain English can take some practice. Also, you have spent years, often decades, on this work and to have to explain it in around one minute is no easy thing.
But our researchers rose to the challenge. Here’s some examples of just how well they did.
What are the latest advances in stem cell research targeting cancer? Can stem cells help people battling COVID-19 or even help develop a vaccine to stop the virus? What are researchers and the scientific community doing to help address the unmet medical needs of underserved communities? Those are just a few of the topics being discussed at the Annual CIRM Alpha Stem Cell Clinic Network Symposium on Thursday, October 8th from 9am to 1.30pm PDT.
Like pretty nearly everything these days the symposium is going to be a virtual event, so you can watch it from the comfort of your own home on a phone or laptop. And it’s free.
The CIRM Alpha Clinics are a network of leading medical centers here in California. They specialize in delivering stem cell and gene therapies to patients. So, while many conferences look at the promise of stem cell therapies, here we deal with the reality; what’s in the clinic, what’s working, what do we need to do to help get these therapies to patients in need?
It’s a relatively short meeting, with short presentations, but that doesn’t mean it will be short on content. Some of the best stem cell researchers in the U.S. are taking part so you’ll learn an awful lot in a short time.
We’ll hear what’s being done to find therapies for
Rare diseases that affect children
Type 1 diabetes
We’ll discuss how to create a patient navigation system that can address social and economic determinants that impact patient participation? And we’ll look at ways that the Alpha Clinic Network can partner with community care givers around California to increase patient access to the latest therapies.
It’s going to be a fascinating day. And did I mention it’s free!
Too many acronyms? Not to worry. It is all perfectly clear in the news release we just sent out about this.
A new collaboration between the California Institute for Regenerative Medicine (CIRM) and the Chan Zuckerberg Initiative (CZI) will advance scientific efforts to respond to the COVID-19 pandemic by collaborating on disseminating single-cell research that scientists can use to better understand the SARS-CoV-2 virus and help develop treatments and cures.
CIRM and CZI have signed a Memorandum of Understanding (MOU) that will combine CIRM’s infrastructure and data collection and analysis tools with CZI’s technology expertise. It will enable CIRM researchers studying COVID-19 to easily share their data with the broader research community via CZI’s cellxgene tool, which allows scientists to explore and visualize measurements of how the virus impacts cell function at a single-cell level. CZI recently launched a new version of cellxgene and is supporting the single-cell biology community by sharing COVID-19 data, compiled by the global Human Cell Atlas effort and other related efforts, in an interactive and scalable way.
“We are pleased to be able to enter into this partnership with CZI,” said Dr. Maria T. Millan, CIRM’s President & CEO. “This MOU will allow us to leverage our respective investments in genomics science in the fight against COVID-19. CIRM has a long-standing commitment to generation and sharing of sequencing and genomic data from a wide variety of projects. That’s why we created the CIRM genomics award and invested in the Stem Cell Hub at the University of California, Santa Cruz, which will process the large complex datasets in this collaboration.”
“Quickly sharing scientific data about COVID-19 is vital for researchers to build on each other’s work and accelerate progress towards understanding and treating a complex disease,” said CZI Single-Cell Biology Program Officer Jonah Cool. “We’re excited to partner with CIRM to help more researchers efficiently share and analyze single-cell data through CZI’s cellxgene platform.”
In March 2020, the CIRM Board approved $5 million in emergency funding to target COVID-19. To date, CIRM has funded 17 projects, some of which are studying how the SARS-CoV-2 virus impacts cell function at the single-cell level.
Three of CIRM’s early-stage COVID-19 research projects will plan to participate in this collaborative partnership by sharing data and analysis on cellxgene.
Dr. Evan Snyder and his team at Sanford Burnham Prebys Medical Discovery Institute are using induced pluripotent stem cells (iPSCs), a type of stem cell that can be created by reprogramming skin or blood cells, to create lung organoids. These lung organoids will then be infected with the novel coronavirus in order to test two drug candidates for treating the virus.
Dr. Brigitte Gomperts at UCLA is studying a lung organoid model made from human stem cells in order to identify drugs that can reduce the number of infected cells and prevent damage in the lungs of patients with COVID-19.
Dr. Justin Ichida at the University of Southern California is trying to determine if a drug called a kinase inhibitor can protect stem cells in the lungs and other organs, which the novel coronavirus selectively infects and kills.
“Cumulative data into how SARS-CoV-2 affects people is so powerful to fight the COVID-19 pandemic,” said Stephen Lin, PhD, the Senior CIRM Science Officer who helped develop the MOU. “We are grateful that the researchers are committed to sharing their genomic data with other researchers to help advance the field and improve our understanding of the virus.”
CZI also supports five distinct projects studying how COVID-19 progresses in patients at the level of individual cells and tissues. This work will generate some of the first single-cell biology datasets from donors infected by SARS-CoV-2 and provide critical insights into how the virus infects humans, which cell types are involved, and how the disease progresses. All data generated by these grants will quickly be made available to the scientific community via open access datasets and portals, including CZI’s cellxgene tool.
Don’t you love it when someone does your job for you and does it so well you have no need to add anything to it! Doesn’t happen very often – sad to say – but this week our friends at UCLA wrote a great article describing the work they are doing to target COVID-19. Best of all, all the work described is funded by CIRM. So read, and enjoy.
Two scientists in a lab at the UCLA Broad Stem Cell Research Center
By Tiare Dunlap, UCLA
As the COVID-19 pandemic rages on, UCLA researchers are rising to the occasion by channeling their specialized expertise to seek new and creative ways to reduce the spread of the virus and save lives. Using years’ — or even decades’ — worth of knowledge they’ve acquired studying other diseases and biological processes, many of them have shifted their focus to the novel coronavirus, and they’re collaborating across disciplines as they work toward new diagnostic tests, treatments and vaccines.
“As a result of the pandemic, everyone on campus is committed to finding ways that their unique expertise can help out,” said Dr. Brigitte Gomperts, professor and vice chair of research in pediatric hematology-oncology and pulmonary medicine at the David Geffen School of Medicine at UCLA and a member of the UCLA Children’s Discovery and Innovation Institute. “So many of my colleagues have repurposed their labs to work on the virus. It’s very seldom that you have one thing that everybody’s working on, and it has been truly inspiring to see how everyone has come together to try and solve this.”
Here’s a look at five projects in which UCLA scientists are using stem cells — which can self-replicate and give rise to all cell types — to take on COVID-19.
Using lung organoids as models to test possible treatments
Dr. Brigitte Gomperts
Gomperts has spent years perfecting methods for creating stem cell–derived three-dimensional lung organoids. Now, she’s using those organoids to study how SARS-CoV-2, the virus that causes COVID-19, affects lung tissue and to rapidly screen thousands of prospective treatments. Because the organoids are grown from human cells and reflect the cell types and architecture of the lungs, they can offer unprecedented insights into how the virus infects and damages the organ.
Gomperts is collaborating with UCLA colleagues Vaithilingaraja Arumugaswami, a virologist, and Robert Damoiseaux, an expert in molecular screening. Their goal is to find an existing therapy that could be used to reduce the spread of infection and associated damage in the lungs.
“We’re starting with drugs that have already been tested in humans because our goal is to find a therapy that can treat patients with COVID-19 as soon as possible,” Gomperts said. Read more.
Repurposing a cancer therapy
Vaithilingaraja Arumugaswami, associate professor of molecular and medical pharmacology at the Geffen School of Medicine
In addition to collaborating with Gomperts, Arumugaswami and Damoiseaux identified the cancer drug Berzosertib as a possible treatment for COVID-19 after screening 430 drug candidates. The drug, which is currently being tested in clinical trials for cancer, works by blocking a DNA repair process that is exploited by solid cancers and the SARS-CoV-2 virus, and the UCLA scientists found that it is very effective at limiting viral replication and cell death.
“Clinical trials have shown that Berzosertib blocks the DNA repair pathway in cancer cells, but has no effects on normal, healthy cells,” Arumugaswami said.
Now, Arumugaswami and Gustavo Garcia Jr., a staff research associate, are testing Berzosertib and additional drug combinations on lung organoids developed in Gomperts’ lab and stem cell–derived heart cells infected with SARS-CoV-2. They suspect that if the drug is administered soon after diagnosis, it could limit the spread of infection and prevent complications. Read more.
Studying the immune response to the virus
Dr. Gay Crooks, professor of pathology and laboratory medicine and of pediatrics at the Geffen School of Medicine, and co-director of the Broad Stem Cell Research Center; and Dr. Christopher Seet,
assistant professor of hematology-oncology at the Geffen School of Medicine
Crooks and Seet are using stem cells to model how immune cells recognize and fight the virus in a lab dish. To do that, they’re infecting blood-forming stem cells — which can give rise to all blood and immune cells — from healthy donors with parts of the SARS-CoV-2 virus and then coaxing the stem cells to produce immune cells called dendritic cells. Dendritic cells devour viral proteins, chop them up into pieces and then present those pieces to other immune cells called T cells to provoke a response.
By studying that process, Crooks and Seet hope to identify which parts of the virus provoke the strongest T-cell responses. Developing an effective vaccine for SARS-CoV-2 will require a deep understanding of how the immune system responds to the virus, and this work could be an important step in that direction, giving researchers and clinicians a way to gauge the effectiveness of possible vaccines.
“When we started developing this project some years ago, we had no idea it would be so useful for studying a viral infection — any viral infection,” Crooks said. “It was only because we already had these tools in place that we could spring into action so fast.” Read more.
Developing a booster that could help a vaccine last longer
A COVID-19 vaccine will need to provide long-term protection from infection. But how long a vaccine protects from infection isn’t solely dependent on the vaccine.
The human body relies on long-living immune cells called T memory stem cells that guard against pathogens such as viruses and bacteria that the body has encountered before. Unfortunately, the body’s capacity to form T memory stem cells decreases with age. So no matter how well designed a vaccine is, older adults who don’t have enough of a response from T memory stem cells will not be protected long-term.
To address that issue, Li is developing an injectable biomaterial vaccine booster that will stimulate the formation of T memory stem cells. The booster is made up of engineered materials that release chemical messengers to stimulate the production of T memory stem cells. When combined with an eventual SARS-CoV-2 vaccine, they would prompt the body to produce immune cells primed to recognize and eliminate the virus over the long term.
“I consider it my responsibility as a scientist and an engineer to translate scientific findings into applications to help people and the community,” Li said. Read more.
Invariant natural killer T cells, or iNKT cells, are the special forces of the immune system. They’re extremely powerful and can immediately recognize and respond to many different intruders, from infections to cancer.
Yang is testing whether iNKT cells would make a particularly effective treatment for COVID-19 because they have the capacity to kill virally infected cells, offer protection from reinfection and rein in the excessive inflammation caused by a hyperactive immune response to the virus, which is thought to be a major cause of tissue damage and death in people with the disease.
One catch, though, is that iNKT cells are incredibly scarce: One drop of human blood contains around 10 million blood cells but only around 10 iNKT cells. That’s where Yang’s research comes in. Over the past several years, she has developed a method for generating large numbers of iNKT cells from blood-forming stem cells. While that work was aimed at creating a treatment for cancer, Yang’s lab has adapted its work over the past few months to test how effective stem cell–derived iNKT cells could be in fighting COVID-19. With her colleagues, she has been studying how the cells work in fighting the disease in models of SARS-CoV-2 infection that are grown from human kidney and lung cells.
“My lab has been developing an iNKT cell therapy for cancer for years,” Yang said. “This means a big part of the work is already done. We are repurposing a potential therapy that is very far along in development to treat COVID-19.” Read more.
“Our center is proud to join CIRM in supporting these researchers as they adapt projects that have spent years in development to meet the urgent need for therapies and vaccines for COVID-19,” said Dr. Owen Witte, founding director of the UCLA Broad Stem Cell Research Center. “This moment highlights the importance of funding scientific research so that we may have the foundational knowledge to meet new challenges as they arise.” Crooks, Gomperts, Seet and Yang are all members of the UCLA Jonsson Comprehensive Cancer Center. Damoiseaux is a professor of molecular and medical pharmacology and director of the Molecular Shared Resource Center at the California NanoSystems Institute at UCLA
There is still a lot that we don’t understand about SARS-CoV-2 (COVID-19), the new coronavirus that has caused a worldwide pandemic. Some patients that contract the virus experiences heart problems, but the reasons are not entirely clear. Pre-existing heart conditions or inflammation and oxygen deprivation that result from COVID-19 have all been implicated but more evidence needs to be collected.
To evaluate this, a joint study between Cedars-Sinai Board of Governors Regenerative Medicine Institute and the UCLA Broad Stem Cell Research Center used human induced pluripotent stem cells (iPSCs), a kind of stem cell that can become any kind of cell in the body and is usually made from skin cells. The iPSCS were converted into heart cells and infected with COVID-19 in order to study the effects of the virus.
The results of this study showed that the iPSC-derived heart cells are susceptible to COVID-19 infection and that the virus can quickly divide inside the heart cells. Furthermore, the infected heart cells showed changes in their ability to beat 72 hours after infection.
In a press release, Dr. Clive Svendsen, senior and co-corresponding author of the study and director of the Cedars-Sinai Board of Governors Regenerative Medicine Institute, elaborated on the results.
“This viral pandemic is predominately defined by respiratory symptoms, but there are also cardiac complications, including arrhythmias, heart failure and viral myocarditis. While this could be the result of massive inflammation in response to the virus, our data suggest that the heart could also be directly affected by the virus in COVID-19.”
Although this study does not perfectly replicate the conditions inside the human body, the iPSC heart cells may also help identify and screen new potential drugs that could alleviate viral infection of the heart.
The research team has already found that treatment with an antibody called ACE2 was able to decrease viral replication on the iPSC heart cells.
In the same press release Dr. Arun Sharma, first author and another co-corresponding author of the study and a research fellow at the Cedars-Sinai Board of Governors Regenerative Medicine Institute, had this to say about the ACE2 antibody.
“By blocking the ACE2 protein with an antibody, the virus is not as easily able to bind to the ACE2 protein, and thus cannot easily enter the cell. This not only helps us understand the mechanisms of how this virus functions, but also suggests therapeutic approaches that could be used as a potential treatment for SARS-CoV-2 infection.”
The study’s third co-corresponding author was Dr. Vaithilingaraja Arumugaswami, an associate professor of molecular and medical pharmacology at the David Geffen School of Medicine at UCLA and member of the Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research.
The full results of this study were published in Cell Reports Medicine.
In late March the CIRM Board approved $5 million in emergency funding for COVID-19 research. The idea was to support great ideas from California’s researchers, some of which had already been tested for different conditions, and see if they could help in finding treatments or a vaccine for the coronavirus.
Less than a month later we were funding a clinical trial and two other projects, one that targeted a special kind of immune system cell that has the potential to fight the virus.
Researchers use stem cells to model the immune response to COVID-19
By Tiare Dunlap
Cities across the United States are opening back up, but we’re still a long way from making the COVID-19 pandemic history. To truly accomplish that, we need to have a vaccine that can stop the spread of infection.
But to develop an effective vaccine, we need to understand how the immune system responds to SARS-CoV-2, the virus that causes COVID-19.
Vaccines work by imitating infection. They expose a person’s immune system to a weakened version or component of the virus they are intended to protect against. This essentially prepares the immune system to fight the virus ahead of time, so that if a person is exposed to the real virus, their immune system can quickly recognize the enemy and fight the infection. Vaccines need to contain the right parts of the virus to provoke a strong immune response and create long-term protection.
Most of the vaccines in development for SARS CoV-2 are using part of the virus to provoke the immune system to produce proteins called antibodies that neutralize the virus. Another way a vaccine could create protection against the virus is by activating the T cells of the immune system.
T cells specifically “recognize” virus-infected cells, and these kinds of responses may be especially important for providing long-term protection against the virus. One challenge for researchers is that they have only had a few months to study how the immune system protects against SARS CoV-2, and in particular, which parts of the virus provoke the best T-cell responses.
For years, they have been perfecting an innovative technology that uses blood-forming stem cells — which can give rise to all types of blood and immune cells — to produce a rare and powerful subset of immune cells called type 1 dendritic cells. Type 1 dendritic cells play an essential role in the immune response by devouring foreign proteins, termed antigens, from virus-infected cells and then chopping them into fragments. Dendritic cells then use these protein fragments to trigger T cells to mount an immune response.
Using this technology, Crooks and Seet are working to pinpoint which specific parts of the SARS-CoV-2 virus provoke the strongest T-cell responses.
Building long-lasting immunity
“We know from a lot of research into other viral infections and also in cancer immunotherapy, that T-cell responses are really important for long-lasting immunity,” said Seet, an assistant professor of hematology-oncology at the David Geffen School of Medicine at UCLA. “And so this approach will allow us to better characterize the T-cell response to SARS-CoV-2 and focus vaccine and therapeutic development on those parts of the virus that induce strong T-cell immunity.”
Crooks’ and Seet’s project uses blood-forming stem cells taken from healthy donors and infected with a virus containing antigens from SARS-CoV-2. They then direct these stem cells to produce large numbers of type 1 dendritic cells using a new method developed by Seet and Suwen Li, a graduate student in Crooks’ lab. Both Seet and Li are graduates of the UCLA Broad Stem Cell Research Center’s training program.
“The dendritic cells we are able to make using this process are really good at chopping up viral antigens and eliciting strong immune responses from T cells,” said Crooks, a professor of pathology and laboratory medicine and of pediatrics at the medical school and co-director of the UCLA Broad Stem Cell Research Center.
When type 1 dendritic cells chop up viral antigens into fragments, they present these fragments on their cell surfaces to T cells. Our bodies produce millions and millions of T cells each day, each with its own unique antigen receptor, however only a few will have a receptor capable of recognizing a specific antigen from a virus.
When a T cell with the right receptor recognizes a viral antigen on a dendritic cell as foreign and dangerous, it sets off a chain of events that activates multiple parts of the immune system to attack cells infected with the virus. This includes clonal expansion, the process by which each responding T cell produces a large number of identical cells, called clones, which are all capable of recognizing the antigen.
“Most of those T cells will go off and fight the infection by killing cells infected with the virus,” said Seet, who, like Crooks, is also a member of the UCLA Jonsson Comprehensive Cancer Center. “However, a small subset of those cells become memory T cells — long-lived T cells that remain in the body for years and protect from future infection by rapidly generating a robust T-cell response if the virus returns. It’s immune memory.”
Producing extremely rare immune cells
This process has historically been particularly challenging to model in the lab, because type 1 dendritic cells are extremely rare — they make up less than 0.1% of cells found in the blood. Now, with this new stem cell technology, Crooks and Seet can produce large numbers of these dendritic cells from blood stem cells donated by healthy people, introduce them to parts of the virus, then see how T cells taken from the blood can respond in the lab. This process can be repeated over and over using cells taken from a wide range of healthy people.
“The benefit is we can do this very quickly without the need for an actual vaccine trial, so we can very rapidly figure out in the lab which parts of the virus induce the best T-cell responses across many individuals,” Seet said.
The resulting data could be used to inform the development of new vaccines for COVID-19 that improve T-cell responses. And the data about which viral antigens are most important to the T cells could also be used to monitor the effectiveness of existing vaccine candidates, and an individual’s immune status to the virus.
“There are dozens of vaccine candidates in development right now, with three or four of them already in clinical trials,” Seet said. “We all hope one or more will be effective at producing immediate and long-lasting immunity. But as there is so much we don’t know about this new virus, we’re still going to need to really dig in to understand how our immune systems can best protect us from infection.”
Supporting basic research into our body’s own processes that can inform new strategies to fight disease is central to the mission of the Broad Stem Cell Research Center.
“When we started developing this project some years ago, we had no idea it would be so useful for studying a viral infection, any viral infection,” Crooks said. “And it was only because we already had these tools in place that we could spring into action so fast.”