National Academy of Medicine honors CIRM Grantees

YOU CAN ALSO LISTEN TO THIS BLOG AS AN AUDIO PODCAST ON SPOTIFY 

As someone who is not always as diligent as he would like to be about sending birthday cards on time, I’m used to sending belated greetings to people. So, I have no shame in sending belated greetings to four CIRM grantees who were inducted into the National Academy of Medicine in 2020.

I say four, but it’s really three and a half. I’ll explain that later.

Being elected to the National Academy of Medicine is, in the NAM’s own modest opinion, “considered one of the highest honors in the fields of health and medicine and recognizes individuals who have demonstrated outstanding professional achievement and commitment to service.”

To be fair, NAM is right. The people elected are among the best and brightest in their field and membership is by election from the other members of NAM, so they are not going to allow any old schmuck into the Academy (which could explain why I am still waiting for my membership).

The CIRM grantees elected last year are:

Dr. Antoni Ribas: Photo courtesy UCLA

Antoni Ribas, MD, PhD, professor of medicine, surgery, and molecular and medical pharmacology, U. C. Los Angeles.

Dr. Ribas is a pioneer in cancer immunology and has devoted his career to developing new treatments for malignant melanoma. When Dr. Ribas first started malignant melanoma was an almost always fatal skin cancer. Today it is one that can be cured.

In a news release Dr. Ribas said it was a privilege to be honored by the Academy: “It speaks to the impact immunotherapy has played in cancer research. When I started treating cases of melanoma that had metastasized to other organs, maybe 1 in 20 responded to treatment. Nobody in their right mind wanted to be a specialist in this field. It was the worst of the worst cancers.”

Looks like he chose his career path wisely.

Dr. Jeffrey Goldberg: Photo courtesy Stanford

Jeffrey Louis Goldberg, MD, PhD, professor and chair of ophthalmology, Stanford University, Palo Alto, Calif.

Dr. Goldberg was honored for his contribution to the understanding of vision loss and ways to reverse it. His lab has developed artificial retinas that transmit images down the optic nerve to the brain through tiny silicon chips implanted in the eye. He has also helped use imaging technology to better improve our ability to detect damage in photoreceptor cells (these are cells in the retina that are responsible for converting light into signals that are sent to the brain and that give us our color vision and night vision)

In a news release he expressed his gratitude saying: “I look forward to serving the goals of the National Academies, and to continuing my collaborative research efforts with my colleagues at the Byers Eye Institute at Stanford and around the world as we further our efforts to combat needless blindness.”

Dr. Mark Anderson; photo courtesy UCSF

Mark S. Anderson, MD, PhD, professor in Diabetes Research, Diabetes Center, U. C. San Francisco.

Dr. Anderson was honored for being a leader in the study of autoimmune diseases such as type 1 diabetes. This focus extends into the lab, where his research examines the genetic control of autoimmune diseases to better understand the mechanisms by which immune tolerance is broken.

Understanding what is happening with the immune system, figuring out why it essentially turns on the body, could one day lead to treatments that can stop that, or even reverse it by boosting immune activity.

Dr. John Dick: Photo courtesy University Health Network, Toronto

Remember at the beginning I said that three and a half CIRM grantees were elected to the Academy, well, Canadian researcher, Dr. John Dick is the half. Why? Well, because the award we funded actually went to UC San Diego’s Dennis Carson but it was part of a Collaborative Funding Partnership Program with Dr. Dick at the University of Toronto. So, we are going to claim him as one of our own.

And he’s a pretty impressive individual to partner with. Dr. Dick is best known for developing a test that led to the discovery of leukemia stem cells. These are cells that can evade surgery, chemotherapy and radiation and which can lead to patients relapsing after treatment. His work helped shape our understanding of cancer and revealed a new strategy for curing it.

Paving the Way

When someone scores a goal in soccer all the attention is lavished on them. Fans chant their name, their teammates pile on top in celebration, their agent starts calling sponsors asking for more money. But there’s often someone else deserving of praise too, that’s the player who provided the assist to make the goal possible in the first place. With that analogy in mind, CIRM just provided a very big assist for a very big goal.

The goal was scored by Jasper Therapeutics. They have just announced data from their Phase 1 clinical trial treating people with Myelodysplastic syndromes (MDS). This is a group of disorders in which immature blood-forming cells in the bone marrow become abnormal and leads to low numbers of normal blood cells, especially red blood cells. In about one in three patients, MDS can progress to acute myeloid leukemia (AML), a rapidly progressing cancer of the bone marrow cells.

The most effective way to treat, and even cure, MDS/AML is with a blood stem cell transplant, but this is often difficult for older patients, because it involves the use of toxic chemotherapy to destroy their existing bone marrow blood stem cells, to make room for the new, healthy ones. Even with a transplant there is often a high rate of relapse, because it’s hard for chemotherapy to kill all the cancer cells.

Jasper has developed a therapy, JSP191, which is a monoclonal antibody, to address this issue. JSP191 helps supplement the current treatment regimen by clearing all the remaining abnormal cells from the bone marrow and preventing relapse. In addition it also means the patients gets smaller doses of chemotherapy with lower levels of toxicity. In this Phase 1 study six patients, between the ages of 65 and 74, were given JSP191 – in combination with low-dose radiation and chemotherapy – prior to getting their transplant. The patients were followed-up at 90 days and five of the six had no detectable levels of MDS/AML, and the sixth patient had reduced levels. None of the patients experienced serious side effects.

Clearly that’s really encouraging news. And while CIRM didn’t fund this clinical trial, it wouldn’t have happened without us paving the way for this research. That’s where the notion of the assist comes in.

CIRM support led to the development of the JSP191 technology at Stanford. Our CIRM funds were used in the preclinical studies that form the scientific basis for using JSP191 in an MDS/AML setting.

Not only that, but this same technique was also used by Stanford’s Dr. Judy Shizuru in a clinical trial for children born with a form of severe combined immunodeficiency, a rare but fatal immune disorder in children. A clinical trial that CIRM funded.

It’s a reminder that therapies developed with one condition in mind can often be adapted to help treat other similar conditions. Jasper is doing just that. It hopes to start clinical trials this year using JSP191 for people getting blood stem cell transplants for severe autoimmune disease, sickle cell disease and Fanconi anemia.

De-stressing stem cells and the Bonnie & Clyde of stem cells

Dr. John Cashman

The cells in our body are constantly signalling with each other, it’s a critical process by which cells communicate not just with other cells but also with elements within themselves. One of the most important signalling pathways is called Wnt. This plays a key role in early embryonic and later development. But when Wnt signalling goes wrong, it can also help spur the growth of cancer.

Researchers at the Human BioMolecular Research Institute (HBRI) and Stanford University, have reported on a compound that can trigger a cascade of events that create stress and ultimately impact Wnt’s ability to control the ability of cells to repair themselves.

In a news release Dr. Mark Mercola, a co-author of a CIRM-funded study – published in the journal Cell Chemical Biology – says this is important: “because it explains why stressed cells cannot regenerate and heal tissue damage. By blocking the ability to respond to Wnt signaling, cellular stress prevents cells from migrating, replicating and differentiating.”

The researchers discovered a compound PAWI-2 that shows promise in blocking the compound that causes this cascade of problems. Co-author Dr. John Cashman says PAWI-2 could lead to treatments in a wide variety of cancers such as pancreatic, breast, prostate and colon cancer.

“As anti-cancer PAWI-2 drug development progresses, we expect PAWI-2 to be less toxic than current therapeutics for pancreatic cancer, and patients will benefit from improved safety, less side effects and possibly with significant cost-savings.”

Dr. Catriona Jamieson: Photo courtesy Moores Cancer Center, UCSD

Speaking of cancer….

Stem cells have many admirable qualities. However, one of their less admirable ones is their ability to occasionally turn into cancer stem cells. Like regular stem cells these have the ability to renew and replicate themselves over time, but as cancer stem cells they use that ability to help fuel the growth and spread of cancer in the body. Now, researchers at U.C. San Diego are trying to better understand how those regular stem cells become cancer stem cells, so they can stop that process.

In a CIRM-funded study Dr. Catriona Jamieson and her team identified two molecules, APOBEC3C and ADAR1, that play a key role in this process.

In a news release Jamieson said: “APOBEC3C and ADAR1 are like the Bonnie and Clyde of pre-cancer stem cells — they drive the cells into malignancy.”

So they studied blood samples from 54 patients with leukemia and 24 without. They found that in response to inflammation, APOBEC3C promotes the rapid production of pre-leukemia stem cells. That in turn enables ADAR1 to go to work, interfering with gene expression in a way that helps those pre-leukemia stem cells turn into leukemia stem cells.

They also found when they blocked the action of ADAR1 or silenced the gene in patient cells in the laboratory, they were able to stop the formation of leukemia stem cells.

The study is published in the journal Cell Reports.

Cures, clinical trials and unmet medical needs

When you have a great story to tell there’s no shame in repeating it as often as you can. After all, not everyone gets to hear first time around. Or second or third time. So that’s why we wanted to give you another opportunity to tune into some of the great presentations and discussions at our recent CIRM Alpha Stem Cell Clinic Network Symposium.

It was a day of fascinating science, heart-warming, and heart-breaking, stories. A day to celebrate the progress being made and to discuss the challenges that still lie ahead.

There is a wide selection of topics from “Driving Towards a Cure” – which looks at some pioneering work being done in research targeting type 1 diabetes and HIV/AIDS – to Cancer Clinical Trials, that looks at therapies for multiple myeloma, brain cancer and leukemia.

The COVID-19 pandemic also proved the background for two detailed discussions on our funding for projects targeting the coronavirus, and for how the lessons learned from the pandemic can help us be more responsive to the needs of underserved communities.

Here’s the agenda for the day and with each topic there’s a link to the video of the presentation and conversation.

Thursday October 8, 2020

View Recording: CIRM Fellows Trainees

9:00am Welcome Mehrdad Abedi, MD, UC Davis Health, ASCC Program Director  

Catriona Jamieson, MD,  View Recording: ASCC Network Value Proposition

9:10am Session I:  Cures for Rare Diseases Innovation in Action 

Moderator: Mark Walters, MD, UCSF, ASCC Program Director 

Don Kohn, MD, UCLA – View Recording: Severe combined immunodeficiency (SCID) 

Mark Walters, MD, UCSF, ASCC Program Director – View Recording: Thalassemia 

Pawash Priyank, View Recording: Patient Experience – SCID

Olivia and Stacy Stahl, View Recording: Patient Experience – Thalassemia

10 minute panel discussion/Q&A 

BREAK

9:55am Session II: Addressing Unmet Medical Needs: Driving Towards a Cure 

Moderator: John Zaia, MD, City of Hope, ASCC Program Direction 

Mehrdad Abedi, MD, UC Davis Health, ASCC Program Director – View Recording: HIV

Manasi Jaiman, MD, MPH, ViaCyte, Vice President, Clinical Development – View Recording: Diabetes

Jeff Taylor, Patient Experience – HIV

10 minute panel discussion/Q&A 

BREAK

10:40am Session III: Cancer Clinical Trials: Networking for Impact 

Moderator: Catriona Jamieson, MD, UC San Diego, ASCC Program Director 

Daniela Bota, MD, PhD, UC Irvine, ASCC Program Director – View Recording:  Glioblastoma 

Michael Choi, MD, UC San Diego – View Recording: Cirmtuzimab

Matthew Spear, MD, Poseida Therapeutics, Chief Medical Officer – View Recording: Multiple Myeloma  

John Lapham, Patient Experience –  View Recording: Chronic lymphocytic leukemia (CLL) 

10 minute panel discussion/Q&A 

BREAK

11:30am Session IV: Responding to COVID-19 and Engaging Communities

Two live “roundtable conversation” sessions, 1 hour each.

Roundtable 1: Moderator Maria Millan, MD, CIRM 

CIRM’s / ASCC Network’s response to COVID-19 Convalescent Plasma, Cell Therapy and Novel Vaccine Approaches

Panelists

Michael Matthay, MD, UC San Francisco: ARDS Program

Rachael Callcut, MD, MSPH, FACS, UC Davis: ARDS Program 

John Zaia, MD, City of Hope: Convalescent Plasma Program 

Daniela Bota, MD, PhD, UC Irvine: Natural Killer Cells as a Treatment Strategy 

Key questions for panelists: 

  • Describe your trial or clinical program?
  • What steps did you take to provide access to disproportionately impacted communities?
  • How is it part of the overall scientific response to COVID-19? 
  • How has the ASCC Network infrastructure accelerated this response? 

Brief Break

Roundtable 2: Moderator Ysabel Duron, The Latino Cancer Institute and Latinas Contra Cancer

View Recording: Roundtable 2

Community Engagement and Lessons Learned from the COVID Programs.  

Panelists

Marsha Treadwell, PhD, UC San Francisco: Community Engagement  

Sheila Young, MD, Charles R. Drew University of Medicine and Science: Convalescent Plasma Program in the community

David Lo, MD, PhD,  UC Riverside: Bringing a public health perspective to clinical interventions

Key questions for panelists: 

  • What were important lessons learned from the COVID programs? 
  • How can CIRM and the ASCC Network achieve equipoise among communities and engender trust in clinical research? 
  • How can CIRM and the ASCC Network address structural barriers (e.g. job constrains, geographic access) that limit opportunities to participate in clinical trials?

Exploring tough questions, looking for answers

COVID-19 and social and racial injustice are two of the biggest challenges facing the US right now. This Thursday, October 8th, we are holding a conversation that explores finding answers to both.

The CIRM Alpha Stem Cell Clinic Network Symposium is going to feature presentations about advances in stem cell and regenerative research, highlighting treatments that are already in the clinic and being offered to patients.

But we’re also going to dive a little deeper into the work we support, and use it to discuss two of the most pressing issues of the day.

One of the topics being featured is research into COVID-19. To date CIRM has funded 17 different projects, including three clinical trials. We’ll talk about how these are trying to find ways to help people infected with the virus, seeing if stem cells can help restore function to organs and tissues damaged by the virus, and if we can use stem cells to help develop safe and effective vaccines.

Immediately after that we are going to use COVID-19 as a way of exploring how the people most at risk of being infected and suffering serious consequences, are also the ones most likely to be left out of the research and have most trouble accessing treatments and vaccines.

Study after study highlights how racial and ethnic minorities are underrepresented in clinical trials and disproportionately affected by debilitating diseases. We have a responsibility to change that, to ensure that the underserved are given the same opportunity to take part in clinical trials as other communities.

How do we do that, how do we change a system that has resisted change for so long, how do we overcome the mistrust that has built up in underserved communities following decades of abuse? We’ll be talking about with experts who are on the front lines of this movement.

It promises to be a lively meeting. We’d love to see you there. It’s virtual – of course – it’s open to everyone, and it’s free.

Here’s where you can register and find out more about the Symposium

Remembering a stem cell pioneer in the fight against HIV/AIDS

Timothy Ray Brown. Photo courtesy Seattle Times

Timothy Ray Brown, a man who was the first person to be cured of HIV, giving hope to millions of people around the world, died at his home in Palm Springs this week. He was just 54 years old.

For years Brown was known simply as “the Berlin patient” because that was where he was living when he made medical history. He was diagnosed with HIV in 1995 and began taking medications to keep the virus under control. He was later also diagnosed with leukemia. He underwent several rounds of treatment for the leukemia, but it kept recurring.

By 2007 Brown’s physician decided the best way to treat the leukemia was with a blood stem cell transplant. But the doctor also wanted to see if using the stem cells from a donor who had a natural immunity to the AIDS virus could help treat Brown’s HIV. While such donors are very rare, the doctor succeeded in finding one whose bone marrow carried the CCR5 gene, a mutation that is believed to provide resistance to HIV. The transplant was a success, putting Brown’s leukemia into remission and eliminating detectable traces of HIV. For the first time in years he was able to stop taking the medications that had helped keep the virus under control.

The procedure quickly garnered world-wide attention. But not everyone was convinced it was real. Some questioned if Brown’s HIV had really been eradicated and speculated that the virus was merely suppressed. But with each passing year, and no signs of the virus recurring, more and more people came to believe it was a cure.

Initially Brown remained in the background, preferring not to be identified. But three years after his transplant he decided he had to come forward and put a face on “the Berlin patient”. In an interview with the website ContagionLive he explained why:

“At some point, I decided I didn’t want to be the only person in the world cured of H.I.V.,” I wanted there to be more. And the way to do that was to show the world who I am and be an advocate for H.I.V.”

He proved to be a powerful advocate, talking at international conferences and serving as living-proof that stem cells could help lead to a cure for HIV.

But while he managed to beat HIV, he could not beat leukemia. He suffered relapses that required another transplant and a difficult recovery. When it returned again this time, there was little physicians could do.

But Timothy Ray Brown did get to see his hope of not being the only patient cured seemingly come true. In September of last year researchers announced they had successfully treated a second person, known as “the London patient” using the same technique that cured Brown.

While it wasn’t the role he would have chosen Brown was a pioneer. His experience showed that a deadly virus could be cured. His courage in not just overcoming the virus but in overcoming his own reluctance to take center stage and becoming a symbol of hope for millions remain and will never die.  

Since Brown’s transplant many other scientists have attempted to replicate the procedure that cured Brown, in the hopes of making it available to many more people.

CIRM has funded three clinical trials targeting HIV, two of which are still active. Dr. Mehrdad Abedi at UC Davis and Dr. John Zaia at City of Hope are both using the patient’s own blood forming stem cells to try and defeat the virus.

If they succeed, some of the credit should go to Timothy Ray Brown, the man who led the way.

Meet the people who are changing the future

Kristin MacDonald

Every so often you hear a story and your first reaction is “oh, I have to share this with someone, anyone, everyone.” That’s what happened to me the other day.

I was talking with Kristin MacDonald, an amazing woman, a fierce patient advocate and someone who took part in a CIRM-funded clinical trial to treat retinitis pigmentosa (RP). The disease had destroyed Kristin’s vision and she was hoping the therapy, pioneered by jCyte, would help her. Kristin, being a bit of a pioneer herself, was the first person to test the therapy in the U.S.

Anyway, Kristin was doing a Zoom presentation and wanted to look her best so she asked a friend to come over and do her hair and makeup. The woman she asked, was Rosie Barrero, another patient in that RP clinical trial. Not so very long ago Rosie was legally blind. Now, here she was helping do her friend’s hair and makeup. And doing it beautifully too.

That’s when you know the treatment works. At least for Rosie.

There are many other stories to be heard – from patients and patient advocates, from researchers who develop therapies to the doctors who deliver them. – at our CIRM 2020 Grantee Meeting on next Monday September 14th Tuesday & September 15th.

It’s two full days of presentations and discussions on everything from heart disease and cancer, to COVID-19, Alzheimer’s, Parkinson’s and spina bifida. Here’s a link to the Eventbrite page where you can find out more about the event and also register to be part of it.

Like pretty much everything these days it’s a virtual event so you’ll be able to join in from the comfort of your kitchen, living room, even the backyard.

And it’s free!

You can join us for all two days or just one session on one day. The choice is yours. And feel free to tell your friends or anyone else you think might be interested.

We hope to see you there.

Stem Cell All-Stars, All For You

goldstein-larry

Dr. Larry Goldstein, UC San Diego

It’s not often you get a chance to hear some of the brightest minds around talk about their stem cell research and what it could mean for you, me and everyone else. That’s why we’re delighted to be bringing some of the sharpest tools in the stem cell shed together in one – virtual – place for our CIRM 2020 Grantee Meeting.

The event is Monday September 14th and Tuesday September 15th. It’s open to anyone who wants to attend and, of course, it’s all being held online so you can watch from the comfort of your own living room, or garden, or wherever you like. And, of course, it’s free.

BotaDaniela2261

Dr. Daniela Bota, UC Irvine

The list of speakers is a Who’s Who of researchers that CIRM has funded and who also happen to be among the leaders in the field. Not surprising as California is a global center for regenerative medicine. And you will of course be able to post questions for them to answer.

srivastava-deepak

Dr. Deepak Srivastava, Gladstone Institutes

The key speakers include:

Larry Goldstein: the founder and director of the UCSD Stem Cell Program talking about Alzheimer’s research

Irv Weissman: Stanford University talking about anti-cancer therapies

Daniela Bota: UC Irvine talking about COVID-19 research

Deepak Srivastava: Gladsone Institutes, talking about heart stem cells

Other topics include the latest stem cell approaches to COVID-19, spinal cord injury, blindness, Parkinson’s disease, immune disorders, spina bifida and other pediatric disorders.

You can choose one topic or come both days for all the sessions. To see the agenda for each day click here. Just one side note, this is still a work in progress so some of the sessions have not been finalized yet.

And when you are ready to register go to our Eventbrite page. It’s simple, it’s fast and it will guarantee you’ll be able to be part of this event.

We look forward to seeing you there.

Perseverance: from theory to therapy. Our story over the last year – and a half

Some of the stars of our Annual Report

It’s been a long time coming. Eighteen months to be precise. Which is a peculiarly long time for an Annual Report. The world is certainly a very different place today than when we started, and yet our core mission hasn’t changed at all, except to spring into action to make our own contribution to fighting the coronavirus.

This latest CIRM Annual Reportcovers 2019 through June 30, 2020. Why? Well, as you probably know we are running out of money and could be funding our last new awards by the end of this year. So, we wanted to produce as complete a picture of our achievements as we could – keeping in mind that we might not be around to produce a report next year.

Dr. Catriona Jamieson, UC San Diego physician and researcher

It’s a pretty jam-packed report. It covers everything from the 14 new clinical trials we have funded this year, including three specifically focused on COVID-19. It looks at the extraordinary researchers that we fund and the progress they have made, and the billions of additional dollars our funding has helped leverage for California. But at the heart of it, and at the heart of everything we do, are the patients. They’re the reason we are here. They are the reason we do what we do.

Byron Jenkins, former Naval fighter pilot who battled back from his own fight with multiple myeloma

There are stories of people like Byron Jenkins who almost died from multiple myeloma but is now back leading a full, active life with his family thanks to a CIRM-funded therapy with Poseida. There is Jordan Janz, a young man who once depended on taking 56 pills a day to keep his rare disease, cystinosis, under control but is now hoping a stem cell therapy developed by Dr. Stephanie Cherqui and her team at UC San Diego will make that something of the past.

Jordan Janz and Dr. Stephanie Cherqui

These individuals are remarkable on so many levels, not the least because they were willing to be among the first people ever to try these therapies. They are pioneers in every sense of the word.

Sneha Santosh, former CIRM Bridges student and now a researcher with Novo Nordisk

There is a lot of information in the report, charting the work we have done over the last 18 months. But it’s also a celebration of everyone who made it possible, and our way of saying thank you to the people of California who gave us this incredible honor and opportunity to do this work.

We hope you enjoy it.

Super charging killer cells to fight leukemia

Colorized scanning electron micrograph of a natural killer cell.
Photo credit: National Institute of Allergy and Infectious Diseases

Racing car drivers are forever tinkering with their cars, trying to streamline them and soup up their engines because while fast is good, faster is better. Researchers do the same things with potential anti-cancer therapies, tinkering with them to make them safer and more readily available to patients while also boosting their ability to fight cancer.

That’s what researchers at the University of California San Diego (UCSD), in a CIRM-funded study, have done. They’ve taken immune system cells – with the already impressive name of ‘natural killer’ (NK) cells – and made them even deadlier to cancers.

These natural killer (NK) cells are considered one of our immune system’s frontline weapons against outside threats to our health, things like viruses and cancer. But sometimes the cancers manage to evade the NKs and spread throughout the body or, in the case of leukemia, throughout the blood.

Lots of researchers are looking at ways of taking a patient’s own NK cells and, in the lab boosting their ability to fight these cancers. However, using a patient’s own cells is both time consuming and very, very expensive.

Dan Kaufman MD

Dr. Dan Kaufman and his team at UCSD decided it would be better to try and develop an off-the-shelf approach, a therapy that could be mass produced from a single batch of NK cells and made available to anyone in need.

Using the iPSC method (which turns tissues like skin or blood into embryonic stem cell-like cells, capable of becoming any other cell in the body) they created a line of NK cells. Then they removed a gene called CISH which slows down the activities of cytokines, acting as a kind of brake or restraint on the immune system.

In a news release, Dr. Kaufman says removing CISH had a dramatic effect, boosting the power of the NK cells.

“We found that CISH-deleted iPSC-derived NK cells were able to effectively cure mice that harbor human leukemia cells, whereas mice treated with the unmodified NK cells died from the leukemia.”

Dr. Kaufman says the next step is to try and develop this approach for testing in people, to see if it can help people whose disease is not responding to conventional therapies.

“Importantly, iPSCs provide a stable platform for gene modification and since NK cells can be used as allogeneic cells (cells that come from donors) that do not need to be matched to individual patients, we can create a line of appropriately modified iPSC-derived NK cells suitable for treating hundreds or thousands of patients as a standardized, ‘off-the-shelf’ therapy.”

The study is published in the journal Cell Stem Cell.