Keeping intestinal stem cells in their prime

Gut stem cells (green) in the small intestine of a mouse.

The average length of the human gut is 25 feet long. That’s equivalent to four really tall people or five really short people lined up head to toe. Intestinal stem cells have the fun job of regenerating and replacing ALL the cells that line the gut. Therefore, it’s important for these stem cells to be able to self-renew, a process that replenishes the stem cell population. If this important biological process is disrupted, the intestine is at risk for diseases like inflammatory bowel disease and cancer.

This week, Stanford Medicine researchers published new findings about the biological processes responsible for regulating the regenerative capacity of intestinal stem cells. Their work, which was partially funded by CIRM, was published in the journal Nature.

Priming gut stem cells to self-renew

Scientists know that the self-renewal of intestinal stem cells is very important for a happy, functioning gut, but the nuances of what molecules and signaling pathways regulate this process have yet to be figured out. The Stanford team, led by senior author and Stanford Professor Dr. Calvin Kuo, studied two signaling pathways, Wnt and R-Spondin, that are involved in the self-renewal of intestinal stem cells in mice.

Dr. Calvin Kuo, Stanford Medicine.

“The cascade of events comprising the Wnt signaling pathway is crucial to stem cell self-renewal,” Dr. Kuo explained in an email exchange. “The Wnt pathway can be induced by either hormones classified as “Wnts” or “R-spondins”.  However, it is not known if Wnts or R-spondins cooperate to induce Wnt signaling, and if these Wnts and R-spondins have distinct functions or if they can mutually substitute for each other.   We explored how Wnts and R-spondins might cooperate to regulate intestinal stem cells – which are extremely active and regenerate the 25-foot lining of the human intestine every week.”

The team used different reagents to activate or block Wnt or R-spondin signaling and monitored the effects on intestinal stem cells. They found that both were important for the self-renewal of intestinal stem cells, but that they played different roles.

“Our work revealed that Wnts and R-spondins are not equivalent and that they have very distinct functions even though they both trigger the Wnt signaling cascade,” said Dr. Kuo. “Both Wnts and R-spondins are required to maintain intestinal stem cells.  However, Wnts perform more of a subservient “priming” function, where they prepare intestinal stem cells for the action of R-spondin, which is the active catalyst for inducing intestinal stem cells to divide.”

The authors believe that this multi-step regulation, involving priming and self-renewal factors could apply to stem cell systems in other organs and tissues in the body. Some of the researchers on this study including Dr. Kuo are pursuing this idea through a new company called Surrozen, which produces artificial bioengineered Wnt molecules that don’t require activation like natural Wnt molecules. These Wnt molecules were used in the current study and are explained in more detail in a separate Nature article published at the same time.

The company believes that artificial Wnts will be useful for understanding stem cell biology and potentially for therapeutic applications. Dr. Kuo explained,

“The new surrogate Wnts are easily produced and can circulate in the bloodstream, unlike natural Wnts.  There may be medical applications of these bioengineered Wnt surrogates in stimulating various stem cell compartments of the body, given the wide range of stem cells that are governed by natural Wnts.”

Don’t Be Afraid: High school stem cell researcher on inspiring girls to pursue STEM careers

As part of our CIRM scholar blog series, we’re featuring the research and career accomplishments of CIRM funded students.

Shannon Larsuel

Shannon Larsuel is a high school senior at Mayfield Senior School in Pasadena California. Last summer, she participated in Stanford’s CIRM SPARK high school internship program and did stem cell research in a lab that studies leukemia, a type of blood cancer. Shannon is passionate about helping people through research and medicine and wants to become a pediatric oncologist. She is also dedicated to inspiring young girls to pursue STEM (Science, Technology, Engineering, and Mathematics) careers through a group called the Stem Sisterhood.

I spoke with Shannon to learn more about her involvement in the Stem Sisterhood and her experience in the CIRM SPARK program. Her interview is below.


Q: What is the Stem Sisterhood and how did you get involved?

SL: The Stem Sisterhood is a blog. But for me, it’s more than a blog. It’s a collective of women and scientists that are working to inspire other young scientists who are girls to get involved in the STEM field. I think it’s a wonderful idea because girls are underrepresented in STEM fields, and I think that this needs to change.

I got involved in the Stem Sisterhood because my friend Bridget Garrity is the founder. This past summer when I was at Stanford, I saw that she was doing research at Caltech. I reconnected with her and we started talking about our summer experiences working in labs. Then she asked me if I wanted to be involved in the Stem Sisterhood and be one of the faces on her website. She took an archival photo of Albert Einstein with a group of other scientists that’s on display at Caltech and recreated it with a bunch of young women who were involved in the STEM field. So I said yes to being in the photo, and I’m also in the midst of writing a blog post about my experience at Stanford in the SPARK program.

Members of The Stem Sisterhood

Q: What does the Stem Sisterhood do?

SL: Members of the team go to elementary schools and girl scout troop events and speak about science and STEM to the young girls. The goal is to inspire them to become interested in science and to teach them about different aspects of science that maybe are not that well known.

The Stem Sisterhood is based in Los Angeles. The founder Bridget wants to expand the group, but so far, she has only done local events because she is a senior in high school. The Stem Sisterhood has an Instagram account in addition to their blog. The blog is really interesting and features interviews with women who are in science and STEM careers.

Q: How has the Stem Sisterhood impacted your life?

SL: It has inspired me to reach out to younger girls more about science. It’s something that I am passionate about, and I’d like to pursue a career in the medical field. This group has given me an outlet to share that passion with others and to hopefully change the face of the STEM world.

Q: How did you find out about the CIRM SPARK program?

SL: I knew I wanted to do a science program over the summer, but I wasn’t sure what type. I didn’t know if I wanted to do research or be in a hospital. I googled science programs for high school seniors, and I saw the one at Stanford University. It looked interesting and Stanford is obviously a great institution. Coming from LA, I was nervous that I wouldn’t be able to get in because the program had said it was mostly directed towards students living in the Bay Area. But I got in and I was thrilled. So that’s basically how I heard about it, because I googled and found it.

Q: What was your SPARK experience like?

SL: My program was incredible. I was a little bit nervous and scared going into it because I was the only high school student in my lab. As a high school junior going into senior year, I was worried about being the youngest, and I knew the least about the material that everyone in the lab was researching. But my fears were quickly put aside when I got to the lab. Everyone was kind and helpful, and they were always willing to answer my questions. Overall it was really amazing to have my first lab experience be at Stanford doing research that’s going to potentially change the world.

Shannon working in the lab at Stanford.

I was in a lab that was using stem cells to characterize a type of leukemia. The lab is hoping to study leukemia in vitro and in vivo and potentially create different treatments and cures from this research. It was so cool knowing that I was doing research that was potentially helping to save lives. I also learned how to work with stem cells which was really exciting. Stem cells are a new advancement in the science world, so being able to work with them was incredible to me. So many students will never have that opportunity, and being only 17 at the time, it was amazing that I was working with actual stem cells.

I also liked that the Stanford SPARK program allowed me to see other aspects of the medical world. We did outreach programs in the Stanford community and helped out at the blood drive where we recruited people for the bone marrow registry. I never really knew anything about the registry, but after learning about it, it really interested me. I actually signed up for it when I turned 18. We also met with patients and their families and heard their stories about how stem cell transplants changed their lives. That was so inspiring to me.

Going into the program, I was pretty sure I wanted to be a pediatric oncologist, but after the program, I knew for sure that’s what I wanted to do. I never thought about the research side of pediatric oncology, I only thought about the treatment of patients. So the SPARK program showed me what laboratory research is like, and now that’s something I want to incorporate into my career as a pediatric oncologist.

I learned so much in such a short time period. Through SPARK, I was also able to connect with so many incredible, inspired young people. The students in my program and I still have a group chat, and we text each other about college and what’s new with our lives. It’s nice knowing that there are so many great people out there who share my interests and who are going to change the world.

Stanford SPARK students.

Q: What was your favorite part of the SPARK program?

SL: Being in the lab every day was really incredible to me. It was my first research experience and I was in charge of a semi-independent project where I would do bacterial transformations on my own and run the gels. It was cool that I could do these experiments on my own. I also really loved the end of the summer poster session where all the students from the different SPARK programs came together to present their research. Being in the Stanford program, I only knew the Stanford students, but there were so many other awesome projects that the other SPARK students were doing. I really enjoyed being able to connect with those students as well and learn about their projects.

Q: Why do you want to pursue pediatric oncology?

SL: I’ve always been interested in the medical field but I’ve had a couple of experiences that really inspired me to become a doctor. My friend has a charity that raises money for Children’s Hospital Los Angeles. Every year, we deliver toys to the hospital. The first year I participated, we went to the hospital’s oncology unit and something about it stuck with me. There was one little boy who was getting his chemotherapy treatment. He was probably two years old and he really inspired to create more effective treatments for him and other children.

I also participated in the STEAM Inquiry program at my high school, where I spent two years reading tons of peer reviewed research on immunotherapy for pediatric cancer. Immunotherapy is something that really interests me. It makes sense that since cancer is usually caused by your body’s own mutations, we should be able to use the body’s immune system that normally regulates this to try and cure cancer. This program really inspired me to go into this field to learn more about how we can really tailor the immune system to fight cancer.

Q: What advice do you have for young girls interested in STEM.

SL: My advice is don’t be afraid. I think that sometimes girls are expected to be interested in less intellectual careers. This perception can strike fear into girls and make them think “I won’t be good enough. I’m not smart enough for this.” This kind of thinking is not good at all. So I would say don’t be afraid and be willing to put yourself out there. I know for me, sometimes it’s scary to try something and know you could fail. But that’s the best way to learn. Girls need to know that they are capable of doing anything and if they just try, they will be surprised with what they can do.

Life after SPARK: CIRM high school intern gets prestigious scholarship to Stanford

As part of our CIRM scholar blog series, we’re featuring the research and career accomplishments of CIRM funded students.

Ranya Odeh

Ranya Odeh

Meet Ranya Odeh. She is a senior at Sheldon high school in Elk Grove, California, and a 2016 CIRM SPARK intern. The SPARK program provides stem cell research internships to underprivileged high school students at leading research institutes in California.

This past summer, Ranya worked in Dr. Jan Nolta’s lab at UC Davis improving methods that turn mesenchymal stem cells into bone and fat cells. During her internship, Ranya did an excellent job of documenting her journey in the lab on Instagram and received a social media prize for her efforts.

Ranya is now a senior in high school and was recently accepted into Stanford University through the prestigious QuestBridge scholarship program. She credits the CIRM SPARK internship as one of the main reasons why she was awarded this scholarship, which will pay for all four years of her college.

I reached out to Ranya after I heard about her exciting news and asked her to share her story so that other high school students could learn from her experience and be inspired by her efforts.


How did you learn about the CIRM SPARK program?

At my high school, one of our assignments is to build a website for the Teen Biotech Challenge (TBC) program at UC Davis. I was a sophomore my first year in the program, and I didn’t feel passionate about my project and website. The year after, I saw that some of my friends had done the CIRM SPARK internship after they participated in the TBC program. They posted pictures about their internship on Instagram, and it looked like a really fun and interesting thing to do. So I decided to build another website (one that I was more excited about) in my junior year on synthetic biology. Then I entered my website in the TBC and got first prize in the Nanobiotechnology field. Because I was one of the winners, I got the SPARK internship.

What did you enjoy most about your SPARK experience?

For me, it was seeing that researchers aren’t just scientists in white lab coats. The Nolta lab (where I did my SPARK internship) had a lot of personality that I wasn’t really expecting. Working with stem cells was so cool but it was also nice to see at the same time that people in the lab would joke around and pull pranks on each other. It made me feel that if I wanted to have a future in research, which I do, it wouldn’t be doing all work all the time.

What was it like to do research for the first time?

Ranya taking care of her stem cells!

Ranya taking care of her stem cells!

The SPARK internship was my first introduction to research. During my first experiment, I remember I was changing media and I thought that I was throwing my cells away by mistake. So I freaked out, but then my mentor told me that I hadn’t and everything was ok. That was still a big deal and I learned a lesson to ask more questions and pay more attention to what I was doing.

Did the SPARK program help you when you applied to college?

Yes, I definitely feel like it did. I came into the internship wanting to be a pharmacist. But my research experience working with stem cells made me want to change my career path. Now I’m looking into a bioengineering degree, which has a research aspect to it and I’m excited for that. Having the SPARK internship on my college application definitely helped me out. I also got to have a letter of recommendation from Dr. Nolta, which I think played a big part as well.

Tell us about the scholarship you received!

I got the QuestBridge scholarship, which is a college match scholarship for low income, high achieving students. I found out about this program because my career counselor gave me a brochure. It’s actually a two-part scholarship. The first part was during my junior year of high school and that one didn’t involve a college acceptance. It was an award that included essay coaching and a conference that told you about the next step of the scholarship.

The second part during my senior year was called the national college match scholarship. It’s an application on its own that is basically like a college application. I submitted it and got selected as a finalist. After I was selected, they have partner colleges that offer full scholarships. You rank your choice of colleges and apply to them separately with a common application. If any of those colleges want to match you and agree to pay for all four years of your college, then you will get matched to your top choice. There’s a possibility that more than one college would want to match you, but you will only get matched with the one that you rank the highest. That was Stanford for me, and I am very happy about that.

Why did you pick Stanford as your top choice?

It’s the closest university to where I grew up that is very prestigious. It was also one of the only colleges I’ve visited. When I was walking around on campus, I felt I could see myself there as a student and with the Stanford community. Also, it will be really nice to be close to my family.

What do you do in your free time?

I don’t have a lot of free time because I’m in Academic Decathalon and I spend most of my time doing that. When I do have free time, I like to watch Netflix, blogs on YouTube, and I try to go to the gym [laughs].

Did you enjoy posting about your SPARK internship on Instagram?

I had a lot of fun posting pictures of me in the lab on Instagram. It was also nice during the summer to see other SPARK students in different programs talk about the same things. We shared jokes about micropipettes and culturing stem cells. It was really cool to see that you’re not the only one posting nerdy science pictures. I also felt a part of a larger community outside of the SPARK program. Even people at my school were seeing and commenting on what I was doing.

UC Davis CIRM SPARK program 2016

UC Davis CIRM SPARK program 2016

I also liked that I got feedback about what I was doing in the lab from other SPARK students. When I posted pictures during my internship, I talked about working with mesenchymal stem cells. Because we all post to the same #CIRMSPARKlab hashtag, I saw students from CalTech commenting that they worked with those stem cells too. That motivated me to work harder and accomplish more in my project. Instagram also helped me with my college application process. I saw that there were other students in the same position as me that were feeling stressed out. We also gave each other feedback on college essays and having advice about what I was doing really helped me out.

Do you think it’s important for students to be on social media?

Yes, I think it’s important with boundaries of course. There are probably some people who are on social media too often, and you should have a balance. But it’s nice to see what other students are doing to prepare for college and to let loose and catch up with your friends.

What advice would you give to younger high school students about pursuing science?

I feel like students can’t expect things to be brought to them. If they are interested in science, they need to take the initiative to find something that they are going to want to do. The CIRM internship was brought to my attention. But I have friends that were interested in medicine and they found their own internships and ways to learn more about what they wanted to do. So my advice is to take initiative and not be scared of rejection, because if you’re scared of rejection you’re not going to do anything.

To hear more about Ranya’s SPARK internship experience, read her blog “Here’s what you missed this summer on the show coats.” You can also follow her on Instagram and Twitter. For more information about the CIRM SPARK internship program, please visit the CIRM website.


Related Links:

New approach could help turn back the clock and reverse damage for stroke patients

stroke

Stroke: courtesy WebMD

Stroke is the leading cause of serious, long-term disability in the US. Every year almost 800,000 people suffer from a stroke. The impact on their lives, and the lives of those around them can be devastating.

Right now the only treatment approved by the US Food and Drug Administration (FDA) is tissue plasminogen activator or tPA. This helps dissolve the blood clot causing most strokes and restores blood flow to the brain. However, to be fully effective this has to be administered within about 3-4 hours after the stroke. Many people are unable to get to the hospital in time and as a result suffer long-term damage, damage that for most people has been permanent.

But now a new study in Nature Medicine shows that might not be the case, and that this damage could even be reversible.

The research, done by a team at the University of Southern California (USC) uses a one-two punch combination of stem cells and a protein that helps those cells turn into neurons, the cells in the brain damaged by a stroke.

First, the researchers induced a stroke in mice and then transplanted human neural stem cells alongside the damaged brain tissue. They then added in a dose of the protein 3K3A-APC or a placebo.

hey found that mice treated with 3K3A-APC had 16 times more human stem-cell derived neurons than the mice treated with the placebo. Those neurons weren’t just sitting around doing nothing. USC’s Berislav Zlokovic, senior author of the paper, says they were actively repairing the stroke-induced damage.

“We showed that 3K3A-APC helps the grafted stem cells convert into neurons and make structural and functional connections with the host’s nervous system. No one in the stroke field has ever shown this, so I believe this is going to be the gold standard for future studies. Functional deficits after five weeks of stroke were minimized, and the mice were almost back to normal in terms of motor and sensorimotor functions. Synapses formed between transplanted cells and host cells, so there is functional activation and cooperation of transplanted cells in the host circuitry.”

The researchers wanted to make sure the transplanted cell-3K3A-ACP combination was really the cause of the improvement in the mice so they then used what’s called an “assassin toxin” to kill the neurons they had created. That reversed the improvements in the treated mice, leaving them comparable to the untreated mice. All this suggests the neurons had become an integral part of the mouse’s brain.

So how might this benefit people? You may remember that earlier this summer Stanford researchers produced a paper showing they had helped some 18 stroke patients, by injecting stem cells from donor bone marrow into their brain. The improvements were significant, including in at least one case regaining the ability to walk. We blogged about that work here

In that study, however, the cells did not become neurons nor did they seem to remain in the brain for an extended period. It’s hoped this new work can build on that by giving researchers an additional tool, the 3K3A-ACP protein, to help the transplanted cells convert to neurons and become integrated into the brain.

One of the other advantages of using this protein is that it has already been approved by the FDA for use in people who have experienced an ischemic stroke, which accounts for about 87 percent of all strokes.

The USC team now hope to get approval from the FDA to see if they can replicate their experiences in mice in people, through a Phase 2 clinical trial.

 

 

 

 

 

 

 

Why TED Talks are ChildX’s Play

When the TED (Technology, Entertainment, Design) talks began in 1984 they were intended to be a one-off event. So much for that idea! Today they are a global event, with TED-sponsored conferences held everywhere from Scotland to Tanzania and India. They have also spawned a mini-industry of copycat events. Well, their slogan is “Ideas Worth Spreading” so in a way they only have themselves to blame for having such a great idea.

Dr. Maria Grazia Roncarolo

Dr. Maria Grazia Roncarolo

The latest place for that idea to take root is Stanford, which is holding a TED-style event focused on critical issues facing child and maternal health. The event – April 2nd and 3rd at Stanford – is called ChildX where x = medicine + technology + innovative treatment + wellbeing. ChildX will bring together some of the leading experts in the field for a series of thoughtful, powerful presentations on the biggest problems facing child and maternal health, and the most exciting research aimed at resolving those problems. One of the main tracks during the two-day event is a section on stem cell and gene therapy. It will raise a number of key questions including:

  • What advances have occurred to enable these therapies to move from science fiction less than a decade ago to the promise of next generation transformative therapeutics?
  • In coming years, how will these therapies allow children with presently incurable diseases to become children living free of disease and reaching their maximum potential?

The moderator for that discussion is Dr. Maria Grazia Roncarolo, and you can hear her talking about the most recent advances in the clinical use of stem cell and gene therapies on this podcast. Anytime you get a chance to hear some of the most compelling speakers in their field talk about exciting innovations that could shape the future, it’s worth taking the time to listen.

Extending the Lease: Stanford Scientists Turn Back Clock on Aging Cells

In the end, all living things—even the cells in our bodies—must die. But what if we could delay the inevitable, even just for a bit? What new scientific advances could come as a result?

Stanford scientists have found a way to temporarily extend the life of an aging cell.

Stanford scientists have found a way to temporarily extend the life of an aging cell.

In research published this week in the FASEB Journal, scientists at the Stanford University School of Medicine have devised a new method that gives aging DNA a molecular facelift.

The procedure, developed by Stanford Stem Cell Scientist Helen Blau and her team at the Baxter Laboratory for Stem Cell Biology, physically lengthens the telomeres—the caps on the ends of chromosomes that protect the cell from the effects of aging.

When born, all cells contain chromosomes capped with telomeres. But during each round of cell division, those telomeres shrink. Eventually, the telomeres shorten to such an extent that the chromosomes can no longer replicate at the rate they once could. For the cell, this is the beginning of the end.

The link between telomeres and cellular aging has been an intense focus in recent years, including the subject of the 2009 Nobel Prize in Physiology or Medicine. Extending the lifespan of cells by preventing—or reversing— the shortening of telomeres can not only boost cell division during laboratory studies, but can also lead to new therapeutic strategies to treat age-related diseases.

“Now we have found a way to lengthen human telomeres… turning back the internal clock in these cells by the equivalent of many years of human life,” explained Blau in a press release. “This greatly increases the number of cells available for studies such as drug testing or disease modeling.”

The method Blau and her team describe involves the use of a modified bit of RNA that boosts the production of the protein telomerase. Telomerase is normally present in high levels in stem cells, but drops off once the cells mature. Blau’s modified RNA gives the aging cells a shot of telomerase, after which they begin behaving like cells half their age. But only for about 48 hours, after which they begin to degrade again.

The temporary nature of this change, say the researchers, offers significant advantages. On the biological level, it means that the treated cells won’t begin dividing out of control indefinitely, minimizing the risk of tumor formation. The study’s first author John Ramunas offers up some additional pluses to their method:

“Existing methods of extending telomeres act slowly, whereas our method acts over just a few days to reverse telomere shortening that occurs over more than a decade of normal aging. This suggests that a treatment using our method could be brief and infrequent.”

Indeed, the genetic disease Duchenne muscular dystrophy is in part characterized by abnormally short telomeres. Blau reasons that their discovery could lead to better treatments for this disease. Their immediate future steps involve testing their method in a variety of cell types. Said Blau:

“We’re working to understand more about the differences among cell types, and how we can overcome those differences to allow this approach to be more universally successful.”

Hear more about stem cells and muscular dystrophy in our recent Spotlight on Disease featuring Helen Blau:

Stem Cells become Tool to Screen for Drugs; Fight Dangerous Heart Infections.

A Stanford study adds a powerful example to our growing list of diseases that have yielded their secrets to iPS-type stem cells grown in a dish. These “disease-in-a-dish” models have become one of the most rapidly growing areas of stem cell science. But this time they did not start with skin from a patient with a genetic disease and see how that genetic defect manifests in cells in a dish. Instead they started with normal tissue and looked at how the resulting cells reacted to viral infection.

They were looking at a nasty heart infection called viral myocarditis, which can begin to cause damage to heart muscle within hours and often leads to death. Existing antiviral drugs have only a modest impact on reducing these infections. So even though there is an urgent need to find better drugs, animal models have not proven very useful and there is no ready supply of human heart tissue for lab study.

To create a ready supply of human heart tissue Joseph Wu’s CIRM-funded team at Stanford started with skin samples from three healthy donors, reprogrammed them into iPS cells and then matured those into heart muscle tissue. Then they took one of the main culprits of this infection, coxsackievirus, and labeled it with a fluorescent marker so they could track its activity in the heart cells.

They were able to verify that the virus infected the cells in a dish just as they do in normal heart tissue. And when they tried treating the cells with four existing antiviral drugs they saw the same modest decrease in the rate of infected cells seen in patients. For one of the drugs that had been shown to cause some heart toxicity, they also saw some damage to the cells in the dish.

They propose that their model can now be used to screen thousands of compounds for potentially more effective and safer drugs. They published their results in Circulation Research July 15.