Why the future of regenerative medicine depends on students getting a living wage

The headline in the journal Nature was intended to grab attention and it definitely did that. It read: ‘The scandal of researchers paid less than a living wage’ The rest of the article built on that saying “The cost-of-living crisis is a fundamental threat for PhD scholars and early-career researchers. They need to be paid properly.”

So, just how poorly are these researchers – PhD candidates and postdoctoral students – paid? Well, according to one survey salaries for PhD students in the biological sciences are below the cost of living at almost every institution in the United States. And imagine trying to live on a sub-standard income in a state as expensive as California?

The outrage is fueled by a survey of more than 3,200 students, three quarters of whom are PhD candidates. Around 85% of the students said inflation is making things even worse and almost half said it was making it hard to complete their courses.

The situation isn’t any better in other countries. In the UK, PhD students often get the equivalent of just $20,400, and that’s after getting a recent big boost of more than $2,000 per year. It’s no wonder English students organized protests calling for better funding. Students in Ireland also staged protests, saying the money they get simply isn’t enough.

The Nature Editorial said this isn’t just a matter of inconvenience for the students, it’s a threat to the future of science: “If students don’t have the resources to support themselves, they can’t put their full efforts into their training and development. And if their stipends aren’t keeping pace with rising rents and the cost of groceries and fuel, any gaps will only grow with time — with devastating results for the ability of research to attract the best talent.”

That’s one of the reasons the California Institute for Regenerative Medicine (CIRM) tries to make sure all the students in its internship programs have enough money to live on. We know it’s hard to focus on work if you are hungry or worried that you don’t have enough money to pay your bills.

When our Board approved a new internship program, called COMPASS (Creating Opportunities through Mentorship and Partnership Across Stem Cell Science) they made sure that enough money was included to cover students living expenses, course fees and even travel to scientific conferences. The Board allocated more than $58,000 a year to support each students, many of whom will come from poor or low-income communities and might not otherwise be able to afford to stay in school.

For our Bridges students, many of whom are also from low-income communities or are the first in their family to attend college, the Board allocated each one around $72,000 worth of support per year.

We know that the future of regenerative medicine in California depends on having a skilled, well-trained, diverse workforce. That doesn’t just mean PhDs doing the research, it also means the technicians and support staff that can help with manufacturing etc. Without a living wage that makes this possible many students will drop out and the field as a whole will struggle. Those most affected will be students from poor backgrounds or from disadvantaged and historically marginalized communities.

We need to support these students in every way we can. If we don’t provide enough financial support for these students to succeed, the field as a whole will be a lot poorer.

Researchers discover how to steer stem cells to regenerate cartilage in joints

Dr. Charles K.F. Chan (Left) and Dr. Michael Longaker (right), Stanford University

Cartilage is a flexible, connective tissue in our joints that is important for cushioning our bones against impacts. This cartilage deteriorates as we age due to normal wear and tear and in some instances excessive damage or a deteriorating disease. The deterioration of cartilage is also the primary cause of joint pain and arthritis, which affects more than 55 million Americans.

It was generally assumed that adult cartilage could not be regenerated after damage. Fortunately, a CIRM funded project by Dr. Charles K.F. Chan, Dr. Michael Longaker, and Dr. Matthew Murphy at Stanford University found a way to use chemical signals to steer skeletal stem cells, which are responsible for the production of bone and cartilage, to regrow cartilage in joints.

Damaged cartilage is currently treated with a technique known as microfracture. Tiny holes are drilled into the surface of a joint, which activates the body’s skeletal stem cells to create fibrocartilage in the joint. Unfortunately, this newly created tissue lacks the flexible properties and cushion of normal cartilage.

The team theorized that there might be a way to influence skeletal stem cells to produce normal cartilage after microfracture. In a mouse model, the researchers used a molecule called BMP2 to initiate bone formation after microfracture. Next, they stopped the bone formation process midway with another molecule called VEGF. The result of this process was the generation of cartilage that had the same important properties as natural cartilage.

In a Stanford press release, Dr. Chan elaborated on these findings.

“What we ended up with was cartilage that is made of the same sort of cells as natural cartilage with comparable mechanical properties, unlike the fibrocartilage that we usually get. It also restored mobility to osteoarthritic mice and significantly reduced their pain.”

To show that this process could work in humans, the team then transferred human tissue into special mice that wouldn’t reject the tissue. They showed that human skeletal stem cells could be steered toward bone development but stopped at the cartilage stage.

The next stage for this research is to conduct experiments in larger animals before eventually starting human clinical trials. The ultimate goal of this treatment would be to help prevent arthritis by rejuvenating cartilage in the joints before it is badly degraded.

In the same press release, Dr. Longaker discusses the advantages of using BMP2 and VEGF for this process.

“BMP2 has already been approved for helping bone heal, and VEGF inhibitors are already used as anti-cancer therapies. This would help speed the approval of any therapy we develop.”

The full results of this study were published in Nature.

Scientists develop immune evading pancreas organoids to treat type 1 diabetes

By Stephen Lin, PhD., CIRM Senior Science Officer

A diabetic child is checking her blood sugar level (self glycaemia).

Type 1 diabetes affects millions of people.  It is a disease where beta islet cells in the pancreas are targeted by the body’s own immune system, destroying the ability to produce insulin.  Without insulin, the body cannot break down sugars from the bloodstream that produce energy for organs and that can lead to many significant health problems including damage to the eyes, nerves, and kidneys.  It is a life-long condition, most commonly triggered in children and teenagers.  However, type 1 diabetes can manifest at any time.  I have a family member who developed type 1 diabetes well into adulthood and had to dramatically alter his lifestyle to live with it. 

Fortunately most people can now live with the disease.  There was a time, dating back to ancient civilizations when getting type 1 diabetes meant early death.  Thankfully, over the past hundred years, treatments have been developed to address the disease.  The first widespread treatment developed in the 1920s was injections of animal insulin isolated from pancreatic islets in cattle and pigs.  Over 50 years later the first genetically engineered human insulin was produced using E. coli bacteria, and variations of this are still used today. However, the disease is still very challenging to manage.  My family member constantly monitors his blood sugar and gives himself injections of insulin to regulate his blood sugar. 

A therapy that can self-regulate blood sugar levels for diabetes would greatly improve the lives of millions of people that deal with the disease.  Pancreatic islet cells transplanted into patients can act as a natural rheostat to continually control blood sugar levels.  Pancreas organ transplantation and islet cell transplantation are treatment options that will accomplish this.  Both options are limited in supply and patients must be kept on life-long immunosuppression so the body does not reject the transplant.  Pancreatic beta cells are also being developed from pluripotent stem cells (these are cells that have the ability to be turned into almost any other kind of cell in the body). 

Now in an advance using pluripotent stem cells, Dr. Ronald Evans and his team at the Salk Institute have created cell clusters called organoids that mimic several properties of the pancreas.  Previously, in work supported by CIRM, the team discovered that a genetic switch called ERR-gamma caused the cells to both produce insulin and be functional to respond to sugar levels in the bloodstream.  They incorporated these findings to create their functional islet clusters that they term “human islet-like islet organoids” (HILOs).  Knowing that the immune system is a major barrier for long term cell replacement therapy, Dr. Evans’ team engineered the HILOs, in work also funded by CIRM, to be resistant to immune cells by expressing the checkpoint protein PD-L1.   PD-L1 is a major target for immunotherapies whose discovery led to a Nobel Prize in 2018.  Expressing PD-L1 acts as an immune blocker.  

When the PD-L1 engineered HILOs were transplanted into diabetic mice with functioning immune systems, they were able to sustain blood glucose control for time periods up to 50 days.  The researchers also saw significantly less mobilization of immune cells after transplantation.  The hope is that these engineered HILOs can eventually be developed as a long term therapy for type 1 diabetes patients without the need for lifelong immunosuppression. 

In a press release, the Salk researchers acknowledge that more research needs to be done before this system can be advanced to clinical trials.  For example, the transplanted organoids need to be tested in mice for longer periods of time to confirm that their effects are long-lasting. More work needs to be done to ensure they would be safe to use in humans, as well. However, the proof of concept has now been established to move forward with these efforts.  Concludes Dr. Evan’s in the announcement, “We now have a product that could potentially be used in patients without requiring any kind of device.”

The full study was published in Nature.

The growth of virtual clinical trials during COVID-19

A participant in a virtual study run by the California firm Science 37 receives materials at home. Credit: Christian Alexander

In the midst of the coronavirus pandemic, there has been a desire to continue to conduct ongoing clinical trials while maintaining social distancing as much as possible. Clinical trial participants have been hesitant to attend routine check-ups and monitoring due to the risk of exposure and health-care workers are stretched beyond their capacity treating COVID-19 patients. As a result of this, many clinical trials have been put on hold.

Since the coronavirus began to spread, Science 37, a company that supports virtual clinical trials conducted mostly online, began to receive hundreds of inquiries every week from pharmaceutical companies, medical centers, and individual investigators. These inquiries revolve around how best to transition to a virtual clinical trial structure, where consultations are performed online and paperwork and data are collected remotely as much as possible.

In an article published in the journal Nature, Jonathan Cotliar, chief medical officer of Science 37, discusses the impact that COVID-19 has had on the company.

“It’s exponentially accelerated the adoption curve of what we were already doing. That’s been a bit surreal.”

One example of a virtual clinical trial was conducted at the University of Minnesota in Minneapolis by Dr. David Boulware and his colleagues. They conducted a randomized, controlled, virtual trial of the malaria drug hydroxychloroquine to find out if it was effective at protecting people from COVID-19 (the results found that it was not). The trial included more than 800 participants and sent them medicine by FedEx delivery while monitoring their health via virtual appointments.

It is anticipated that even as the coronavirus pandemic and social distancing measures come to an end, virtual clinical trials will continue to be used in the future. Patient advocates have long pushed for these kinds of trials to ease the burden of clinical trial participation, which tends to be more challenging for underrepresented and underserved communities. As a result of the increase in virtual trials, the FDA has released guidelines for conducting virtual trials in order to streamline the process. It is possible that virtual trials might speed up enrollment of participants, which could help speed up the drug-development process while still maintaining rigorous standards.

How quitting smoking helps your lungs regenerate; a discovery could lead to new ways to repair damaged lungs; and encouraging news in a stroke recovery trial

Photo courtesy Lindsay Fox

Smoking is one of the leading causes of preventable death not just in the US, but worldwide. According to the US Centers for Disease Control and Prevention tobacco causes an estimated seven million deaths around the world, every single year. And for every person who dies, another 30 live with a serious smoking-related illness. Clearly quitting is a good idea. Now a new study adds even more incentive to do just that.

Scientists at the Welcome Trust Sanger Institute and University College London in the UK, found that quitting smoking did more than just stop further damage to the lungs. They found that cells in the lining of the lungs that were able to avoid being damaged, were able to regrow and repopulate the lung, helping repair damaged areas.

In an article in Science Daily Dr Peter Campbell, a joint senior author of the study, said: “People who have smoked heavily for 30, 40 or more years often say to me that it’s too late to stop smoking — the damage is already done. What is so exciting about our study is that it shows that it’s never too late to quit — some of the people in our study had smoked more than 15,000 packs of cigarettes over their life, but within a few years of quitting many of the cells lining their airways showed no evidence of damage from tobacco.”

The study is published in the journal Nature.

Researchers at UCLA have also made a discovery that could help people with lung disease.

They examined the lungs of people with cancer and compared them to the lungs of healthy people. They were able to identify a group of molecules, called the Wnt/beta-catenin signaling pathway, that appear to influence the activity of stem cells that are key to maintaining healthy lungs. Too much activity can tilt the balance away from healthy lungs to ones with mutations that are more prone to developing tumors.

In a news release Dr. Brigitte Gomperts, the lead author of the study, says although this work has only been done in mice so far it has tremendous potential: “We think this could help us develop a new therapy that promotes airway health. This could not only inform the treatment of lung cancer, but help prevent its progression in the first place.”

The study is published in the journal Cell Reports.

CIRM has funded some of Dr. Gomperts earlier work in this area.

And there’s encouraging news for people trying to recover from a stroke. Results from ReNeuron’s Phase 2 clinical trial show the therapy appears to help people who have experienced some level of disability following a stroke.

ReNeuron says its CTX therapy – made from neural stem cells – was given to 23 people who had moderate to severe disability resulting from an ischemic stroke. The patients were, on average, seven months post stroke.

In the study, published in the Journal of Neurology, Neurosurgery & Psychiatry, researchers used the Modified Rankin Scale (mRS), a measure of disability and dependence to assess the impact of the therapy. The biggest improvements were seen in a group of 14 patients who had limited movement of one arm.

  • 38.5% experienced at least a one-point improvement on mRS six months after being treated.
  • 50% experienced a one-point improvement 12 months after being treated.

If that doesn’t seem like a big improvement, then consider this. Moving from an mRS 3 to 2 means that a person with a stroke regains their ability to live independently.

The therapy is now being tested in a larger patient group in the PISCES III clinical trial.

Breakthrough image could lead to better therapies

Image of a blood stem cell in its natural environment: Photo courtesy UC Merced

When it comes to using stem cells for therapy you don’t just need to understand what kinds of cell to use, you also need to understand the environment that is best for them. Trying to get stem cells to grow in the wrong environment would be like trying to breed sheep in a pond. It won’t end well.

But for years scientists struggled to understand how to create the right environment, or niche, for these cells. The niche provides a very specific micro-environment for stem cells, protecting them and enabling them to self-renew over long periods of time, helping repair damaged tissues and organs in the body.

But different stem cells need different niches, and those involve both physical and chemical properties, and getting that mixture right has been challenging. That in turn has slowed down our ability to use those cells to develop new therapies.

UC Merced’s Joel Spencer in the lab: Photo courtesy UC Merced

Now UC Merced’s Professor Joel Spencer and his team have developed a way of capturing an image of hematopoietic or blood stem cells (HSCs), inside their niche in the bone marrow. In an article on UC Merced News, he says this could be a big step forward.

“Everyone knew black holes existed, but it took until last year to directly capture an image of one due to the complexity of their environment. It’s analogous with stem cells in the bone marrow. Until now, our understanding of HSCs has been limited by the inability to directly visualize them in their native environment.

“This work brings an advancement that will open doors to understanding how these cells work which may lead to better therapeutics for hematologic disorders including cancer.”

In the past, studying HSCs involved transplanting them into a mouse or other animal that had undergone radiation to kill off its own bone marrow cells. It enabled researchers to track the HSCs but clearly the new environment was very different than the original, natural one. So, Spencer and his team developed new microscopes and imaging techniques to study cells and tissues in their natural environment.  

In the study, published in the journal Nature, Spencer says all this is only possible because of recent technological breakthroughs.

“My lab is seeking to answer biological questions that were impossible until the advancements in technology we have seen in the past couple decades. You need to be able to peer inside an organ, inside a live animal and see what’s happening as it happens.”

Being able to see how these cells behave in their natural environment may help researchers learn how to recreate that environment in the lab, and help them develop new and more effective ways of using those cells to repair damaged tissues and organs.

Two CIRM supported studies highlighted in Nature as promising approaches for blood disorders

Blood stem cells (blue) are cleared from the bone marrow (purple) before new stem cells can be transplanted.Credit: Dennis Kunkel Microscopy/SPL

Problems with blood stem cells, a type of stem cell in your bone marrow that gives rise to various kinds of blood cells, can sometimes result in blood cancer as well as genetic and autoimmune diseases.

It is because of this that researchers have looked towards blood stem cell transplants, which involves replacing a person’s defective blood stem cells with healthy ones take from either a donor or the patient themselves.

However, before this can be done, the existing population of defective stem cells must be eradicated in order to allow the transplanted blood stem cells to properly anchor themselves into the bone marrow. Current options for this include full-body radiation or chemotherapy, but these approaches are extremely toxic.

But what if there was a way to selectively target these blood stem cells in order to make the transplants much safer?

An article published in Nature highlights the advancements made in the field of blood stem cell transplantation, some of which is work that is funded by yours truly.

One of the approaches highlighted involves the work that we funded related to Forty Seven and an antibody created that inhibits a protein called CD47.

The article discusses how Forty Seven tested two antibodies in monkeys. One antibody blocks the activity of a molecule called c-Kit, which is found on blood stem cells. The other is the antibody that blocks CD47, which is found on some immune cells. Inhibiting CD47 allows those immune cells to sweep up the stem cells that were targeted by the c-Kit antibody, thereby boosting its effectiveness. In early tests, the two antibodies used together reduced the number of blood stem cells in bone marrow. The next step for this team is to demonstrate that the treatment clears out the old supply of stem cells well enough to allow transplanted cells to flourish.

You can read more about the CD47 antibody in a previous blog post.

Another notable segment of this article is the CIRM funded trial that is being conducted by Dr. Judith Shizuru at Stanford University. This clinical trial also uses an antibody that targets c-Kit found on blood stem cells.

The purpose of this trial is to wipe out the problematic blood stem cells in infants with X-linked Severe combined immunodeficiency (SCID), a rare fatal genetic disorder that leaves infants without a functional immune system, in order to introduce properly functioning blood stem cells. Dr. Shizuru and her team found that transplanted blood stem cells, in this case from donors who did not have the disease, successfully took hold in the bone marrow of four out of six of the babies.

You can read more about Dr. Shizuru’s work in a previous blog post as well.

Newly discovered “don’t eat me” signal shows potential for ovarian and triple-negative breast cancer treatment

Stanford researchers have found that cancer cells have a protein called CD24 on their surface that enables them to protect themselves against the body’s immune cells.
Courtesy of Shutterstock

Getting a breast cancer diagnosis is devastating news in and of itself. Currently, there are treatment options that target three different types of receptors, which are named hormone epidermal growth factor receptor 2 (HER-2), estrogen receptors (ER), and progesterone receptors (PR), commonly found in breast cancer cells, . Unfortunately, in triple-negative breast cancer, which occurs in 10-20% of breast cancer cases, all three receptors are absent, making this form of breast cancer very aggressive and difficult to treat.

In recent years, researchers have discovered that proteins on the cell surface can tell macrophages, an immune cell designed to detect and engulf foreign or abnormal cells, not to eat and destroy them. This can be useful to help normal cells keep the immune system from attacking them, but cancer cells can also use these “don’t eat me” signals to hide from the immune system. 

An illustration of a macrophage, a vital part of the immune system, engulfing and destroying a cancer cell. Antibody 5F9 blocks a “don’t eat me” signal emitted from cancer cells. Courtesy of Forty Seven, Inc.

In fact, because of this concept, a CIRM-funded clinical trial is being conducted that uses an antibody called 5F9 to block a “don’t eat me” signal known as CD47 that is found in cancer cells. The results of this trial, which have been announced in a previous blog post, are very promising.

Further building on this concept, a CIRM-funded study has now discovered a potential new target for triple-negative breast cancer as well as ovarian cancer. Dr. Irv Weissman and a team of researchers at Stanford University have discovered an additional “don’t eat me” signal called CD24 that cancers seem to use to evade detection and destruction by the immune system.

In a press release, Dr. Weissman talks about his work with CD47 and states that,

“Finding that not all patients responded to anti-CD47 antibodies helped fuel our research at Stanford to test whether non-responder cells and patients might have alternative ‘don’t eat me’ signals.” 

The scientists began by looking for signals that were produced more highly in cancers than in the tissues from which the cancers arose. It is here that they discovered CD24 and then proceeded to implant human breast cancer cells in mice for testing. When the CD24 signaling was blocked, the mice’s immune system attacked the cancer cells.

An important discovery was that ovarian and triple-negative breast cancer were highly affected by blocking of CD24 signaling. The other interesting discovery was that the effectiveness of CD24 blockage seems to be complementary to CD47 blockage. In other words, some cancers, like blood cancers, seem to be highly susceptible to blocking CD47, but not to CD24 blockage. For other cancers, like ovarian cancer, the opposite is true. This could suggest that most cancers will be susceptible to the immune system by blocking the CD24 or CD47 signal, and that cancers may be even more vulnerable when more than one “don’t eat me” signal is blocked.

Dr. Weissman and his team are now hopeful that potential therapies to block CD24 signaling will follow in the footsteps of the clinical trials related to CD47.

The full results to the study were published in Nature.

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.

CIRM funded study identifies potential drug target for deadly heart condition

Joseph Wu is co-senior author of a study that demonstrates how patient-derived heart cells can help scientists better study the heart and screen potential therapies. Photo courtesy of Steve Fisch

Heart disease continues to be the number one cause of death in the United States. An estimated 375,000 people have a genetic form of heart disease known as familial dilated cardiomyopathy. This occurs when the heart muscle becomes weakened in one chamber in the heart, causing the open area of the chamber to become enlarged or dilated. As a result of this, the heart can no longer beat regularly, causing shortness of breath, chest pain and, in severe cases, sudden and deadly cardiac arrest.

A diagram of a normal heart compared to one with the dilated cardiomyopathy

A CIRM funded study by a team of researchers at Stanford University looked further into this form of genetic heart disease by taking a patient’s skin cells and converting them into stem cells known as induced pluripotent stem cells (iPSCs), which can become any type of cell in the body. These iPSCs were then converted into heart muscle cells that pulse just as they do in the body. These newly made heart muscle cells beat irregularly, similar to what is observed in the genetic heart condition.

Upon further analysis, the researchers linked a receptor called PGDF to cause various genes to be more highly activated in the mutated heart cells compared to normal ones. Two drugs, crenolanib and sunitinib, interfere with the PGDF receptor. After treating the abnormal heart cells, they began beating more regularly, and their gene-activation patterns more closely matched those of cells from healthy donors.

These two drugs are already FDA-approved for treating various cancers, but previous work shows that the drugs may damage the heart at high doses. The next step would be determining the right dose of the drug. The current study is part of a broader effort by the researchers to use these patient-derived cells-in-a-dish to screen for and discover new drugs.

Dr. Joseph Wu, co-senior author of this study, and his team have generated heart muscle cells from over 1,000 patients, including those of Dr. Wu, his son, and his daughter. In addition to using skin cells, the same technique to create heart cells from patients can also be done with 10 milliliters of blood — roughly two teaspoons.

In a news release, Dr. Wu is quoted as saying,

“With 10 milliliters of blood, we can make clinically usable amounts of your beating heart cells in a dish…Our postdocs have taken my blood and differentiated my pluripotent stem cells into my brain cells, heart cells and liver cells. I’m asking them to test some of the medications that I might need to take in the future.”

The full results of this study were published in Nature.