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.
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
Dr. Vaithi Arumugaswami: Photo courtesy UCLA
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
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
If someone told you they were working on lungs in a dish you might be forgiven for thinking that’s the worst idea for a new recipe you have ever heard of. But in the case of Dr. Evan Snyder and his team at Sanford Burnham Prebys Medical Discovery Institute it could be a recipe for a powerful new tool against COVID-19.
Earlier this month the CIRM Board approved almost $250,000 for Dr. Snyder and his team to use human induced pluripotent stem cells (hiPSCs), a type of stem cell that can be created by reprogramming skin or blood cells, to create any other cell in the body, including lung cells.
These cells will then be engineered to become 3D lung organoids or “mini lungs in a dish”. The importance of this is that these cells resemble human lungs in a way animal models do not. They have the same kinds of cells, structures and even blood vessels that lungs do.
These cells will then be infected with the coronavirus and then be used to test two drugs to see if those drugs are effective against the virus.
In a news release Dr. Snyder says these cells have some big advantages over animal models, the normal method for early stage testing of new therapies.
“Mini lungs will also help us answer why some people with COVID-19 fare worse than others. Because they are made from hiPSCs, which come from patients and retain most of the characteristics of those patients, we can make ‘patient-specific’ mini lungs. We can compare the drug responses of mini lungs created from Caucasian, African American, and Latino men and women, as well as patients with a reduced capacity to fight infection to make sure that therapies work effectively in all patients. If not, we can adjust the dose or drug regime to help make the treatment more effective.
“We can also use the mini lungs experimentally to evaluate the effects of environmental toxins that come from cigarette smoking or vaping to make sure the drugs are still effective; and emulate the microenvironmental conditions in the lungs of patients with co-morbidities such as diabetes, and heart or kidney disease.”
To date CIRM has funded 15 projects targeting COVID-19, including three that are in clinical trials.
The Stem Cellar 