Salk Scientists Unlock New Secrets of Autism Using Human Stem Cells

Autism is a complex neurodevelopmental disorder whose mental, physical, social and emotional symptoms are highly variable from person to person. Because individuals exhibit different combinations and severities of symptoms, the concept of autism spectrum disorder (ASD) is now used to define the range of conditions.

There are many hypotheses for why autism occurs in humans (which some estimates suggest now affects around 3.5 million people in the US). Some of the disorders are thought to be at the cellular level, where nerve cells do not develop normally and organize properly in the brain, and some are thought to be at the molecular level where the building blocks in cells don’t function properly. Scientists have found these clues by using tools such as studying human genetics and animal models, imaging the brains of ASD patients, and looking at the pathology of ASD brains to see what has gone wrong to cause the disease.

Unfortunately, these tools alone are not sufficient to recreate all aspects of ASD. This is where cellular models have stepped in to help. Scientists are now developing human stem cell derived models of ASD to create “autism in a dish” and are finding that the nerve cells in these models show characteristics of these disorders.

Stem cell models of autism and ASD

We’ve reported on some of these studies in previous blogs. A group from UCSD lead by CIRM grantee Alysson Muotri used induced pluripotent stem cells or iPS cells to model non-syndromic autism (where autism is the primary diagnosis). The work has been dubbed the “Tooth Fairy Project” – parents can send in their children’s recently lost baby teeth which contain cells that can be reprogrammed into iPS cells that can then be turned into brain cells that exhibit symptoms of autism. By studying iPS cells from individuals with non-syndromic autism, the team found a mutation in the TRPC6 gene that was linked to abnormal brain cell development and function and is also linked to Rett syndrome – a rare form of autism predominantly seen in females.

Another group from Yale generated “mini-brains” or organoids derived from the iPS cells of ASD patients. They specifically found that ASD mini-brains had an increased number of a type of nerve cell called inhibitory neurons and that blocking the production of a protein called FOXG1 returned these nerve cells back to their normal population count.

Last week, a group from the Salk Institute in collaboration with scientists at UC San Diego published findings about another stem cell model for ASD that offers new clues into the early neurodevelopmental defects seen in ASD patients.  This CIRM-funded study was led by senior author Rusty Gage and was published last week in the Nature journal Molecular Psychiatry.

Unlocking clues to autism using patient stem cells

Gage and his team were fascinated by the fact that as many as 30 percent of people with ASD experience excessive brain growth during early in development. The brains of these patients have more nerve cells than healthy individuals of the same age, and these extra nerve cells fail to organize properly and in some cases form too many nerve connections that impairs their overall function.

To understand what is going wrong in early stages of ASD, Gage generated iPS cells from ASD individuals who experienced abnormal brain growth at an early age (their brains had grown up to 23 percent faster when they were toddlers compared to normal toddlers). They closely studied how these ASD iPS cells developed into brain stem cells and then into nerve cells in a dish and compared their developmental progression to that of healthy iPS cells from normal individuals.

Neurons derived from people with ASD (bottom) form fewer inhibitory connections (red) compared to those derived from healthy individuals (top panel). (Salk Institute)

Neurons derived from people with ASD (bottom) form fewer inhibitory connections (red) compared to those derived from healthy individuals (top panel). (Salk Institute)

They quickly observed a problem with neurogenesis – a term used to describe how brain stem cells multiply and create new nerve cells in the brain. Brain stem cells derived from ASD iPS cells displayed more neurogenesis than normal brain stem cells, and thus were creating an excess amount of nerve cells. The scientists also found that the extra nerve cells failed to form as many synaptic connections with each other, an essential process that allows nerve cells to send signals and form a functional network of communication, and also behaved abnormally and overall had less activity compared to healthy neurons. Interestingly, they saw fewer inhibitory neuron connections in ASD neurons which is contrary to what the Yale study found.

The abnormal activity observed in ASD neurons was partially corrected when they treated the nerve cells with a drug called IGF-1, which is currently being tested in clinical trials as a possible treatment for autism. According to a Salk news release, “the group plans to use the patient cells to investigate the molecular mechanisms behind IGF-1’s effects, in particular probing for changes in gene expression with treatment.”

Will stem cells be the key to understanding autism?

It’s clear that human iPS cell models of ASD are valuable in helping tease apart some of the mechanisms behind this very complicated group of disorders. Gage’s opinion is that:

“This technology allows us to generate views of neuron development that have historically been intractable. We’re excited by the possibility of using stem cell methods to unravel the biology of autism and to possibly screen for new drug treatments for this debilitating disorder.”

However, to me it’s also clear that different autism stem cell models yield different results, but these differences are likely due to which populations the iPS cells are derived from. Creating more cell lines from different ASD subpopulations will surely answer more questions about the developmental differences and differences in brain function seen in adults.

Lastly, one of the co-authors on the study, Carolina Marchetto, made a great point in the Salk news release by acknowledging that their findings are based on studying cells in a dish, not actual patient’s brains. However, Marchetto believes that these cells are useful tools for studying autism:

“It never fails to amaze me when we can see similarities between the characteristics of the cells in the dish and the human disease.”

Rusty Gage and Carolina Marchetto. (Salk Institute)

Rusty Gage and Carolina Marchetto. (Salk Institute)


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The Spanish Inquisition and a tale of two stem cell agencies

Monty

Monty Python’s Spanish Inquisition sketch: Photo courtesy Daily Mail UK

It’s not often an article on stem cell research brings the old, but still much loved, British comedy series Monty Python into the discussion but a new study in the journal Cell Stem Cell does just that, comparing the impact of CIRM and the UK’s Regenerative Medicine Platform (UKRMP).

The article, written by Fiona Watt of King’s College London and Stanford’s Irv Weissman (a CIRM grantee – you can see his impressive research record here) looks at CIRM and UKRMP’s success in translating stem cell research into clinical applications in people.

It begins by saying that in research, as in real estate, location is key:

“One thing that is heavily influenced by location, however, is our source of funding. This in turn depends on the political climate of the country in which we work, as exemplified by research on stem cells.”

And, as Weissman and Watt note, political climate can have a big impact on that funding. CIRM was created by the voters of California in 2004, largely in response to President George W. Bush’s restrictions on the use of federal funds for embryonic stem cell research. UKRMP, in contrast was created by the UK government in 2013 and designed to help strengthen the UK’s translational research sector. CIRM was given $3 billion to do its work. UKRMP has approximately $38 million.

Inevitably the two agencies took very different approaches to funding, shaped in part by the circumstances of their birth – one as a largely independent state agency, the other created as a tool of national government.

CIRM, by virtue of its much larger funding was able to create world-class research facilities, attract top scientists to California and train a whole new generation of scientists. It has also been able to help some of the most promising projects get into clinical trials. UKRMP has used its more limited funding to create research hubs, focusing on areas such as cell behavior, differentiation and manufacturing, and safety and effectiveness. Those hubs are encouraged to work collaboratively, sharing their expertise and best practices.

Weissman and Watt touch on the problems both agencies ran into, including the difficulty of moving even the best research out of the lab and into clinical trials:

“Although CIRM has moved over 20 projects into clinical trials most are a long way from becoming standard therapies. This is not unexpected, as the interval between discovery and FDA approved therapeutic via clinical trials is in excess of 10 years minimum.”

 

And here is where Monty Python enters the picture. The authors quote one of the most famous lines from the series: “Nobody expects the Spanish Inquisition – because our chief weapon is surprise.”

They use that to highlight the surprises and uncertainty that stem cell research has gone through in the more than ten years since CIRM was created. They point out that a whole category of cells, induced pluripotent stem (iPS) cells, didn’t exist until 2006; and that few would have predicted the use of gene/stem cell therapy combinations. The recent development of the CRISPR/Cas9 gene-editing technology shows the field is progressing at a rate and in directions that are hard to predict; a reminder that that researchers and funding agencies should continue to expect the unexpected.

With two such different agencies the authors wisely resist the temptation to make any direct comparisons as to their success but instead conclude:

“…both CIRM and UKRMP have similar goals but different routes (and funding) to achieving them. Connecting people to work together to move regenerative medicine into the clinic is an over-arching objective and one that, we hope, will benefit patients regardless of where they live.”

Spotlight on CIRM Grantee Joe Wu: Clinical Trials for Heart Disease in a Dish?

It’s always exciting to read a science article featuring a talented scientist who is breaking boundaries in the field of regenerative medicine. It’s especially exciting to us at CIRM when the scientist is a CIRM grantee.

Last week, OZY published a fun and inspiring piece on Stanford scientist Joe Wu. Dr. Wu is the Director of the Stanford Cardiovascular Institute and his lab studies how stem cells (both adult and pluripotent) function and how they can be used to model heart diseases and screen for new drug therapies. He also is a CIRM grantee and has a Disease Team Therapy Development grant that aims to clinically test human embryonic stem cell-derived cardiomyocytes (heart cells) in end stage heart failure patients.

Dr. Joe Wu. (Image Source: Sean Culligan/OZY)

Dr. Joe Wu. (Image Source: Sean Culligan/OZY)

The OZY piece does a great job of highlighting Dr. Wu’s recent efforts to use human induced pluripotent stem cells (iPS cells) to make heart tissue in a dish and model cardiovascular disease. And without getting too technical, the article explains Dr. Wu’s larger mission to combine precision medicine and stem cell research to identify drugs that would be best suited for specific patient populations.

The article commented,

“He envisions treatments based on an individual’s own iPS cells. For example, a popular breast cancer drug has an 8 percent chance of giving patients heart failure. In Wu’s world, we’d test the drug on stem cells first, and if a patient lands in that 8 percent, begin treatment for the side effects preemptively or avoiding the drug totally and avoiding heart failure, too.”

Basically, Dr. Wu sees the future of clinical trials in a dish using human stem cells. “His goal is to take these stem cells from thousands of patients to create a genetically diverse enough bank that will allow for “clinical trials in a dish” — Wu’s go-to phrase.”

Instead of following the traditional drug development paradigm that takes more than 10 years, billions of dollars, and unfortunately usually ends in failure, Dr. Wu wants to follow an accelerated path where stem cells are used for drug toxicity and efficacy testing.

This alternative path could improve overall drug development and approval by the FDA. The article explained,

“Testing drugs on stem cells will give big pharma and the FDA vastly improved heads up for toxic complications. Stem cells are “absolutely” the best avenue going forward, says Norman Stockbridge, director of the division of cardiovascular and renal products at the FDA’s Center for Drug Evaluation and Research.”

Not everyone is on the same page with Dr. Wu’s bold vision of the future of precision medicine, stem cells, and treatments for heart disease. Some believe he is overly ambitious, however top scientists in the stem cell field have praised Dr. Wu’s “systematic approach” to research and how he doesn’t stop at data discovery, he focuses on the big picture and how his work can ultimately help patients.

You can read more about Dr. Wu’s research on his lab website and I highly encourage you to check out the OZY article which is a great example of science communication for the general public.


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Stem cell stories that caught our eye: a surprising benefit of fasting, faster way to make iPSCs, unlocking the secret of leukemia cancer cells

Here are some stem cell stories that caught our eye this past week. Some are groundbreaking science, others are of personal interest to us, and still others are just fun.

Fasting

Is fasting the fountain of youth?

Among the many insults our bodies endure in old age is a weakened immune system which leaves the elderly more susceptible to infection. Chemotherapy patients also face the same predicament due to the immune suppressing effects of their toxic anticancer treatments. While many researchers aim to develop drugs or cell therapies to protect the immune system, a University of Southern California research report this week suggests an effective alternative intervention that’s startlingly straightforward: fasting for 72 hours.

The study published in Cell Stem Cell showed that cycles of prolonged fasting in older mice led to a decrease in white blood cells which in turn set off a regenerative burst of blood stem cells. This restart of the blood stem cells replenished the immune system with new white blood cells. In a pilot Phase 1 clinical trial, cancer patients who fasted 72 hours before receiving chemotherapy maintained normal levels of white blood cells.

A look at the molecular level of the process pointed to a decrease in the levels of a protein called PKA in stem cells during the fasting period. In a university press release carried by Science Daily, the study leader, Valter Longo, explained the significance of this finding:

“PKA is the key gene that needs to shut down in order for these stem cells to switch into regenerative mode. It gives the ‘okay’ for stem cells to go ahead and begin proliferating and rebuild the entire system. And the good news is that the body got rid of the parts of the system that might be damaged or old, the inefficient parts, during the fasting. Now, if you start with a system heavily damaged by chemotherapy or aging, fasting cycles can generate, literally, a new immune system.”

In additional to necessary follow up studies, the team is looking into whether fasting could benefit other organ systems besides the immune system. If the data holds up, it could be that regular fasting or direct targeting of PKA could put us on the road to a much more graceful and healthier aging process.

4955224186_31f969e6fd_m

Faster, cheaper, safer way to use iPS cells

Science, like traffic in any major city, never moves quite as quickly as you would like, but now Japanese researchers are teaming up to develop a faster, and cheaper way of using iPSC’s , pluripotent stem cells that are reprogrammed from adult cells, for transplants.

Part of the beauty of iPSCs is that because those cells came from the patient themselves, there is less risk of rejection. But there are problems with this method. Taking adult cells and turning them into enough cells to treat someone can take a long time. It’s expensive too.

But now researchers at Kyoto University and three other institutions in Japan have announced they are teaming up to change that. They want to create a stockpile of iPSCs that are resistant to immunological rejection, and are ready to be shipped out to researchers.

Having a stockpile of ready-to-use iPSCs on hand means researchers won’t have to wait months to develop their own, so they can speed up their work.

Shinya Yamanaka, who developed the technique to create iPSCs and won the Nobel prize for his efforts, say there’s another advantage with this collaboration. In a news article on Nikkei’s Asian Review he said these cells will have been screened to make sure they don’t carry any potentially cancer-causing mutations.

“We will take all possible measures to look into the safety in each case, and we’ll give the green light once we’ve determined they are sound scientifically. If there is any concern at all, we will put a stop to it.”

CIRM is already working towards a similar goal with our iPSC Initiative.

Unlocking the secrets of leukemia stem cells

the-walking-dead-season-6-zombies

Zombies: courtesy “The Walking Dead”

Any article that has an opening sentence that says “Cancer stem cells are like zombies” has to be worth reading. And a report in ScienceMag  that explains how pre-leukemia white blood cell precursors become leukemia cancer stem cells is definitely worth reading.

The article is about a study in the journal Cell Stem Cell by researchers at UC San Diego. The senior author is Catriona Jamieson:

“In this study, we showed that cancer stem cells co-opt an RNA editing system to clone themselves. What’s more, we found a method to dial it down.”

An enzyme called ADAR1 is known to spur cancer growth by manipulating small pieces of genetic material known as microRNA. Jamieson and her team wanted to track how that was done. They discovered it is a cascade of events, and that once the first step is taken a series of others quickly followed on.

They found that when white blood cells have a genetic mutation that is linked to leukemia, they are prone to inflammation. That inflammation then activates ADAR1, which in turn slows down a segment of microRNA called let-7 resulting in increased cell growth. The end result is that the white blood cells that began this cascade become leukemia stem cells and spread an aggressive and frequently treatment-resistant form of the blood cancer.

Having uncovered how ADAR1 works Jamieson and her team then tried to find a way to stop it. They discovered that by blocking the white blood cells susceptibility to inflammation, they could prevent the cascade from even starting. They also found that by using a compound called 8-Aza they could impede ADAR1’s ability to stimulate cell growth by around 40 percent.

Jamieson

Catriona Jamieson – definitely not a zombie

Jamieson says the findings open up all sorts of possibilities:

“Based on this research, we believe that detecting ADAR1 activity will be important for predicting cancer progression. In addition, inhibiting this enzyme represents a unique therapeutic vulnerability in cancer stem cells with active inflammatory signaling that may respond to pharmacologic inhibitors of inflammation sensitivity or selective ADAR1 inhibitors that are currently being developed.”

This wasn’t a CIRM-funded study but we have supported other projects by Dr. Jamieson that have led to clinical trials.

 

 

 

 

What’s the big idea? Or in this case, what’s the 19 big ideas?

supermarket magazineHave you ever stood in line in a supermarket checkout line and browsed through the magazines stacked conveniently at eye level? (of course you have, we all have). They are always filled with attention-grabbing headlines like “5 Ways to a Slimmer You by Christmas” or “Ten Tips for Rock Hard Abs” (that one doesn’t work by the way).

So with those headlines in mind I was tempted to headline our latest Board meeting as: “19 Big Stem Cell Ideas That Could Change Your Life!”. And in truth, some of them might.

The Board voted to invest more than $4 million in funding for 19 big ideas as part of CIRM’s Discovery Inception program. The goal of Inception is to provide seed funding for great, early-stage ideas that may impact the field of human stem cell research but need a little support to test if they work. If they do work out, the money will also enable the researchers to gather the data they’ll need to apply for larger funding opportunities, from CIRM and other institutions, in the future

The applicants were told they didn’t have to have any data to support their belief that the idea would work, but they did have to have a strong scientific rational for why it might

As our President and CEO Randy Mills said in a news release, this is a program that encourages innovative ideas.

Randy Mills, Stem Cell Agency President & CEO

Randy Mills, CIRM President & CEO

“This is a program supporting early stage ideas that have the potential to be ground breaking. We asked scientists to pitch us their best new ideas, things they want to test but that are hard to get funding for. We know not all of these will pan out, but those that do succeed have the potential to advance our understanding of stem cells and hopefully lead to treatments in the future.”

So what are some of these “big” ideas? (Here’s where you can find the full list of those approved for funding and descriptions of what they involve). But here are some highlights.

Alysson Muotri at UC San Diego has identified some anti-retroviral drugs – already approved by the Food and Drug Administration (FDA) – that could help stop inflammation in the brain. This kind of inflammation is an important component in several diseases such as Alzheimer’s, autism, Parkinson’s, Lupus and Multiple Sclerosis. Alysson wants to find out why and how these drugs helps reduce inflammation and how it works. If he is successful it is possible that patients suffering from brain inflammation could immediately benefit from some already available anti-retroviral drugs.

Stanley Carmichael at UC Los Angeles wants to use induced pluripotent stem (iPS) cells – these are adult cells that have been genetically re-programmed so they are capable of becoming any cell in the body – to see if they can help repair the damage caused by a stroke. With stroke the leading cause of adult disability in the US, there is clearly a big need for this kind of big idea.

Holger Willenbring at UC San Francisco wants to use stem cells to create a kind of mini liver, one that can help patients whose own liver is being destroyed by disease. The mini livers could, theoretically, help stabilize a person’s own liver function until a transplant donor becomes available or even help them avoid the need for liver transplantation in the first place. Considering that every year, one in five patients on the US transplant waiting list will die or become too sick for transplantation, this kind of research could have enormous life-saving implications.

We know not all of these ideas will work out. But all of them will help deepen our understanding of how stem cells work and what they can, and can’t, do. Even the best ideas start out small. Our funding gives them a chance to become something truly big.


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Adding new stem cell tools to the Parkinson’s disease toolbox

Understanding a complicated neurodegenerative disorder like Parkinson’s disease (PD) is no easy task. While there are known genetic risk factors that cause PD, only about 10 percent of cases are linked to a genetic cause. The majority of patients suffer from the sporadic form of PD, where the causes are unknown but thought to be a combination of environmental, lifestyle and genetic factors.

Unfortunately, there is no cure for PD, and current treatments only help PD patients manage the symptoms of their disease and inevitably lose their effectiveness over time. Another troubling issue is that doctors and scientists don’t have good ways to predict who is at risk for PD, which closes an important window of opportunity for delaying the onset of this devastating disease.

Scientists have long sought relevant disease models that mimic the complicated pathological processes that occur in PD. Current animal models have failed to truly represent what is going on in PD patients. But the field of Parkinson’s research is not giving up, and scientists continue to develop new and improved tools, many of them based on human stem cells, to study how and why this disease happens.

New Stem Cell Tools for Parkinson’s

Speaking of new tools, scientists from the Buck Institute for Research on Aging published a study that generated 10 induced pluripotent stem cell (iPS cell) lines derived from PD patients carrying well known genetic mutations linked to PD. These patient cell lines will be a useful resource for studying the underlying causes of PD and for potentially identifying therapeutics that prevent or treat this disorder. The study was partly funded by CIRM and was published today in the journal PLOS ONE.

Dr. Xianmin Zeng, the senior author on the study and Associate Professor at Buck Institute, developed these disease cell lines as tools for the larger research community to use. She explained in a news release:

Xianmin Zeng, Buck Institute

Xianmin Zeng, Buck Institute

“We think this is the largest collection of patient-derived lines generated at an academic institute. We believe the [iPS cell] lines and the datasets we have generated from them will be a valuable resource for use in modeling PD and for the development of new therapeutics.”

 

The datasets she mentions are part of a large genomic analysis that was conducted on the 10 patient stem cell lines carrying common PD mutations in the SNCA, PARK2, LRRK2, or GBA genes as well as control stem cell lines derived from healthy patients of the same age. Their goal was to identify changes in gene expression in the Parkinson’s stem cell lines as they matured into the disease-affected nerve cells of the brain that could yield clues into how PD develops at the molecular level.

Using previous methods developed in her lab, Dr. Zeng coaxed the iPS cell lines into neural stem cells (brain stem cells) and then further into dopaminergic neurons – the nerve cells that are specifically affected and die off in Parkinson’s patients. Eight of the ten patient lines were able to generate neural stem cells, and all of the neural stem cell lines could be coaxed into dopaminergic neurons – however, some lines were better at making dopaminergic neurons than others.

Dopaminergic neurons derived from induced pluripotent stem cells. (Xianmin Zeng, Buck Institute)

Dopaminergic neurons derived from induced pluripotent stem cells. (Xianmin Zeng, Buck Institute)

When they analyzed these lines, surprisingly they found that the overall gene expression patterns were similar between diseased and healthy cell lines no matter what cell stage they were at (iPS cells, neural stem cells, and neurons). They next stressed the cells by treating them with a drug called MPTP that is known to cause Parkinson’s like symptoms in humans. MPTP treatment of dopaminergic neurons derived from PD patient iPS cell lines did cause changes in gene expression specifically related to mitochondrial function and death, but these changes were also seen in the healthy dopaminergic neurons.

Parkinson’s, It’s complicated…

These interesting findings led the authors to conclude that while their new stem cell tools certainly display some features of PD, individually they are not sufficient to truly model all aspects of PD because they represent a monogenic (caused by a single mutation) form of the disease.

They explain in their conclusion that the power of their PD patient iPS cell lines will be achieved when combined with additional patient lines, better controls, and more focused data analysis:

“Our studies suggest that using single iPSC lines for drug screens in a monogenic disorder with a well-characterized phenotype may not be sufficient to determine causality and mechanism of action due to the inherent variability of biological systems. Developing a database to increase the number of [iPS cell] lines, stressing the system, using isogenic controls [meaning the lines have identical genes], and using more focused strategies for analyzing large scale data sets would reduce the impact of line-to-line variations and may provide important clues to the etiology of PD.”

Brian Kennedy, Buck Institute President and CEO, also pointed out the larger implications of this study by commenting on how these stem cell tools could be used to identify potential drugs that specifically target certain Parkinson’s mutations:

Brian Kennedy, Buck Institute

Brian Kennedy, Buck Institute

“This work combined with dozens of other control, isogenic and reporter iPSC lines developed by Dr. Zeng will enable researchers to model PD in a dish. Her work, which we are extremely proud of, will help researchers dissect how genes interact with each other to cause PD, and assist scientists to better understand what experimental drugs are doing at the molecular level to decide what drugs to use based on mutations.”

Overall, what inspires me about this study is the author’s mission to provide a substantial number of PD patient stem cell lines and genomic analysis data to the research community. Hopefully their efforts will inspire other scientists to add more stem cell tools to the Parkinson’s tool box. As the saying goes, “it takes an army to move a mountain”, in the case of curing PD, the mountain seems more like Everest, and we need all the tools we can get.


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Scientists Make Insulin-Secreting Cells from Stem Cells of Type 1 Diabetes Patients

Stem cell research for diabetes is in a Golden Age. In the past few years, scientists have developed methods to generate insulin-secreting pancreatic beta cell-like cells from embryonic stem cells, induced pluripotent stem cells (iPS cells), and even directly from human skin. We’ve covered a number of recent studies in this area on our blog, and you can read more about them here.

Patients with type 1 diabetes (T1D) suffer from an autoimmune response that attacks and kills the beta cells in their pancreas. Without these important cells, patients can no longer secrete insulin in response to increased glucose or sugar levels in the blood. Cell replacement is evolving into an attractive therapeutic option for patients with T1D. Replacing lost beta cells in the pancreas is a more permanent and less burdensome solution than the daily insulin shots that many T1D patients currently take.

Cell replacement therapy for type 1 diabetes

Stem cells are the latest strategy that scientists are pursuing for T1D cell replacement therapy. The strategy involves generating beta cells from pluripotent stem cells, either embryonic or iPS cells, that function similarly to beta cells found in a healthy human pancreas. Making beta cells from a patient’s own iPS cells is the ideal way to go because this autologous form (self to self) of transplantation would reduce the chances  of transplant rejection because a patient’s own cells would be put back into their body.

Scientists have generated beta cell-like cells from iPS cells derived from T1D patients previously, but the biological nature and function of these cells wasn’t up to snuff in a side by side comparison with beta cells from non-diabetic patients. They didn’t express the appropriate beta cell markers and failed to secrete the appropriate levels of insulin when challenged in a dish and when transplanted into animal models.

However, a new study published yesterday in Nature Communications has overcome this hurdle. Teams from the Washington University School of Medicine in St. Louis and the Harvard Stem Cell Institute have developed a method that makes beta cells from T1D patient iPS cells that behave very similarly to true beta cells. This discovery has the potential to offer personalized stem cell treatments for patients with T1D in the near future.

These beta cells could be the real deal

Their current work is based off of an earlier 2014 study – from the lab of Douglas Melton at Harvard – that generated functional human beta cells from both embryonic and iPS cells of non-diabetic patients. In the current study, the authors were interested in learning whether it was possible to generate functional beta cells from T1D patients and whether these cells would be useful for transplantation given that they could potentially be less functional than non-diabetic beta cells.

The study’s first author, Professor Jeffrey Millman from the Washington University School of Medicine, explained:

Jeffrey Millman

Jeffrey Millman

“There had been questions about whether we could make these cells from people with type 1 diabetes. Some scientists thought that because the tissue would be coming from diabetes patients, there might be defects to prevent us from helping the stem cells differentiate into beta cells. It turns out that’s not the case.”

After generating beta cells from T1D iPS cells, Millman and colleagues conducted a series of experiments to test the beta cells both in a dish and in mice. They found that the T1D-derived beta cells expressed the appropriate beta cell markers, secreted insulin in the presence of glucose, and responded well to anti-diabetic drugs that stimulated the beta cells to secrete even more insulin.

When T1D beta cells were transplanted into mice that lacked an immune system, they survived and functioned similarly to transplanted non-diabetic beta cells. When the mice were treated with a drug that killed off their mouse beta cells, the surviving human T1D beta cells were successful in regulating the blood glucose levels in the mice and kept them alive.

Beta cells derived from type 1 diabetes patient stem cells (top) express the same beta cell markers as beta cells derived from non-diabetic (ND) patients.

Beta cells derived from type 1 diabetes patient stem cells (top) express the same beta cell markers as beta cells derived from non-diabetic (ND) patients. (Nature Communications)

Big Picture

The authors concluded that the beta cells they generated from T1D iPS cells were indistinguishable from healthy beta cells derived from non-diabetic patients. In a news release, Millman commented on the big picture of their study:

“In theory, if we could replace the damaged cells in these individuals with new pancreatic beta cells — whose primary function is to store and release insulin to control blood glucose — patients with type 1 diabetes wouldn’t need insulin shots anymore. The cells we’ve manufactured sense the presence of glucose and secrete insulin in response. And beta cells do a much better job controlling blood sugar than diabetic patients can.”

He further commented that the T1D- derived beta cells “could be ready for human research in three to five years. At that time, Millman expects the cells would be implanted under the skin of diabetes patients in a minimally invasive surgical procedure that would allow the beta cells access to a patient’s blood supply.”

“What we’re envisioning is an outpatient procedure in which some sort of device filled with the cells would be placed just beneath the skin,” he said.

In fact, such devices already exist. CIRM is funding a type 1 diabetes clinical trial sponsored by the San Diego based company ViaCyte. They are currently testing a combination drug delivery system that implants a medical device capsule containing pancreatic progenitor cells derived from human embryonic stem cells. Once implanted, the progenitor cells are expected to specialize into mature pancreatic cells including beta cells that secrete insulin.


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New study says stem cells derived from older people may have more problems than we thought.

heart muscle from iPS

iPS-generated heart muscle cells

Ever since 2006 when Japanese researcher Shinya Yamanaka showed that you could take an adult cell, such as those in your skin, and reprogram it to act like an embryonic stem cell, the scientific world has looked at these induced pluripotent stem (iPS) cells as a potential game changer. They had the ability to convert a person’s own cells into any other kind of cell in the body, potentially offering a way of creating personalized treatments for a wide variety of diseases.

Fears that this reprogramming method might create some cancer-causing genetic mutations seemed to have been eased when two recent studies suggested this approach is relatively safe and unlikely to lead to any tumors in patients. We funded one of those studies and blogged about it.

Reason for caution

But now a new study in the journal Cell Stem Cell  says “not so fast”. The study says the older the person is, the greater the chance that any iPS cells derived from their tissue could contain potentially harmful mutations, but not in the places you would normally think.

A team at Oregon Health and Science University, led by renowned scientist Shoukhrat Mitalipov, took skin and blood samples from a 72-year-old man. The scientists examined the DNA from those samples, then reprogrammed those cells into iPS cells, and examined the DNA from the new stem cells.

Mitalipov-2

Shoukhrat Mitalipov: photo courtesy Oregon Health and Science University

When they looked at the cells collectively the levels of mutations in the new iPS cells appeared to be quite low. But when they looked at individual cells, they noticed a wide variety of mutations in the mitochondria in those cells.

Now, mitochondria play an important role in the life of a cell. They act as a kind of battery, providing the power a cell needs to perform a variety of functions such as signaling and cell growth. But while they are part of the cell, mitochondria have their own genomes. It was here that the researchers found the mutations that raised questions.

Older cells have more problems

Next they repeated the experiment but this time took skin and blood samples from 14 people between the ages of 24 and 72. They found that  older people had more genetic mutations in their mitochondrial DNA that were then transferred to the iPS cells derived from those people. In some cases up to 80 percent of the iPS cell lines generated showed mitochondrial mutations. That’s really important because the greater the amount of mutated mitochondrial DNA in a cell, the more its ability to function is compromised.

In a news release, Mitalipov says this should cause people to pause before using iPS cells derived from an older person for therapeutic purposes:

“Pathogenic mutations in our mitochondrial DNA have long been thought to be a driving force in aging and age-related diseases, though clear evidence was missing. Now with that evidence at hand, we know that we must screen stem cells for mutations or collect them at younger age to ensure their mitochondrial genes are healthy. This foundational knowledge of how cells are damaged in the natural process of aging may help to illuminate the role of mutated mitochondria in degenerative disease.”

To be clear, the researchers are not saying these iPS cells from older people should never be used, only that they need to be carefully screened to ensure they are not seriously damaged before being transplanted into a patient.

A possible solution

Mitalipov suggests a simple way around the problem would be to identify the iPS cell with the best mitochondria, and then use that as the basis for a new cell line that could then be used to create a new therapy.

Taosheng Huang, a researcher at the Mitochondrial Disorders Program at Cincinnati Children’s Hospital Medical Center, is quoted in the news release saying the lesson is clear:

“If you want to use iPS cells in a human, you must check for mutations in the mitochondrial genome. Every single cell can be different. Two cells next to each other could have different mutations or different percentages of mutations.”

Stem cells from “love-handles” could help diabetes patients

Love handles usually get a bad rap, but this week, a study from Switzerland claims that stem cells taken from the fat tissue of “love handles” could one day benefit diabetes patients.

An islet of a mouse pancreas containing beta cells shown in green. (wikipedia)

An islet of a mouse pancreas containing beta cells shown in green. (wikipedia)

The study, which was published in Nature Communications, generated the much coveted insulin-secreting pancreatic beta cells from human induced pluripotent stem cells (iPS cells) in a dish. When exposed to glucose (sugar), beta cells secrete the hormone insulin, which can tell muscle and fat tissue to absorb excess glucose if there is too much around. Without these important cells, your body wouldn’t be able to regulate the sugar levels in your blood, and you would be at high risk for getting diabetes.

Diabetic patients can take daily shots of insulin to manage their disease, but scientists are looking to stem cells for a more permanent solution. Their goal is to make bonafide beta cells from human pluripotent stem cells in a dish that behave exactly the same as ones living in a normal human pancreas. Current methods to make beta cells from stem cells are complex, too often yield inconsistent results and generate multiple other cell types.

Turning fat tissue into pancreatic cells

The Switzerland study developed a novel method for making beta cells from iPS cells that is efficient and gives more consistent results. The iPS cells were genetically reprogrammed from mesenchymal stem cells that had been extracted from the fat tissue of a 50-year old woman. To create insulin-secreting beta cells, the group developed a synthetic control network that directed the iPS cells step by step down the path towards becoming pancreatic beta cells.

The synthetic control network coordinated the expression of genes called transcription factors that are important for pancreatic development. The network could be thought of as an orchestra. At the start of a symphony, the conductor signals to different instrument groups to begin and then directs the tempo and sound of the performance, making sure each instrument plays at the right time.

In the case of this study, the synthetic gene network coordinates expression of three pancreatic transcription factors: Ngn2, Pdx1, and MafA. When the expression of these genes was coordinated in a precise way that mimicked natural beta cell development, the pancreatic progenitor cells developed into functioning beta-like cells that secreted insulin in the presence of glucose.

The diagram shows the dynamics of the most important growth factors during differentiation of human induced pluripotent stem cell to beta-like cells. Credit: ETH Zurich

The diagram shows the dynamics of the most important transcription factors during differentiation of human induced pluripotent stem cell to beta-like cells. Credit: ETH Zurich

Pros of love handle-derived beta cells

This technology has advantages over current stem cell-derived beta cell generating methods, which typically use combinations of genetic reprogramming factors, chemicals, or proteins. Senior author on the study, Martin Fussenegger, explained in a news release that his study’s method has more control over the timing of pancreatic gene expression and as a result is more efficient, having the ability to turn three out of four fat stem cells into functioning beta cells.

Another benefit to this technology is the potential for making personalized stem cell treatments for diabetes sufferers. Patient-specific beta cells derived from iPS cells can be transplanted without fear of immune rejection (it’s what’s called an autologous stem cell therapy). Some diabetes patients have received pancreatic tissue transplants from donors, but they have to take immunosuppressive drugs and even then, there is no guarantee that the transplant will survive and work properly for an extended period of time.

Fussenegger commented:

“With our beta cells, there would likely be no need for this action, since we can make them using endogenous cell material taken from the patient’s own body. This is why our work is of such interest in the treatment of diabetes.”

More work to do

While these findings are definitely exciting, there is still a long road ahead. The authors found that their beta cells did not perform at the same level as natural beta cells. When exposed to glucose, the stem cell-derived beta cells failed to secrete the same amount of insulin. So it sounds like the group needs to do some tweaking with their method in order to generate more mature beta cells.

Lastly, it’s definitely worth looking at the big picture. This study was done in a culture dish, and the beta cells they generated were not tested in animals or humans. Such transplantation experiments are necessary to determine whether love-handle derived beta cells will be an appropriate and effective treatment for diabetes patients.

A CIRM funded team at San Diego-based company ViaCyte seems to have successfully gotten around the issue of maturing beta cells from stem cells and is already testing their therapy in clinical trials. Their study involves transplanting so-called pancreatic progenitor cells (derived from embryonic stem cells) that are only part way down the path to becoming beta cells. They transplant these cells in an encapsulated medical device placed under the skin where they receive natural cues from the surrounding tissue that direct their growth into mature beta cells. Several patients have been transplanted with these cells in a CIRM funded Phase 1/2 clinical trial, but no data have been released as yet.


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New stem cell could offer new ways to study birth defects

tony-parenti-stem-cell-2

Tony Parenti, MSU Ph.D student in cell and molecular biology

You never know what you are going to find in the trash. For a group of intrepid researchers at Michigan State University their discovery could lead to new ways of studying birth defects and other reproductive problems. Because what they found in what’s normally considered cellular trash was a new kind of stem cell.

The cell is called an induced extraembryonic endoderm stem (iXEN) cell. The team’s findings are reported in the journal Stem Cell Reports and here’s how lead author Tony Parenti described what they found:

“Other scientists may have seen these cells before, but they were considered to be defective, or cancer-like. Rather than ignore these cells that have been mislabeled as waste byproducts, we found gold in the garbage.”

Here’s the backstory to this discovery. For years researchers have considered embryonic stem cells as the “gold standard” for pluripotent cells, the kind that can be differentiated, or changed, into all kinds of cell in the body.

But studies in mice show that in addition to creating these pluripotent stem cells, the mouse embryo also produces extraembryonic endoderm or XEN cells. For a long time it was believed the gene expression of XEN cells affected the pluripotent stem cells, but the XEN cells were usually thought to be cancer-like, something that occurred as a byproduct of the developing embryo.

Searching through the trash

And that’s how things stayed until the research team at MSU noticed a bunch of XEN-like cells showing up every time they created induced pluripotent stem (iPS) cells – a kind of man-made equivalent of embryonic cells with the ability to turn into any other kind of cell but derived in a different way, reprogrammed from adult cells.

So they set out to see how important these, what they called induced or iXEN, cells were to the development of iPS cells. The researchers took  adult mouse cells and reprogrammed them into iPS cells and noticed colonies of iXEN cells in these cultures.

The first goal was to make sure these iXEN cells weren’t cancer-causing, as many researchers believed. This took six months but at the end of it not only were they able to demonstrate that the cells aren’t cancer-causing in a cell culture dish, but that they are a new type of stem cell.

Next step was to see how important endodermal genes are in the formation of iXEN cells. They found that decreasing endodermal gene expression led to a two-fold decrease in the number of iXEN cells and a significant increase in the number of iPS cells.

Competitors not collaborators

They concluded that the parallel pathways that generate pluripotent and XEN cells are in competition with each other and not in support of each other during reprogramming. By suppressing one they were able to boost the other. To their delight they had stumbled on a more efficient way of creating iPS cells.

While the discovery of a new kind of stem cell is always exciting there’s a catch to this; we still don’t know if XEN cells are found in humans. But this discovery gives the researchers additional tools to try and find the answer to that question.

Amy Ralston, a co-author of the study, said in a news release:

“It’s a missing tool that we don’t have yet. It’s true that XEN cells have characteristics that pluripotent stem cells do not have. Because of those traits, iXEN cells can shed light on reproductive diseases. If we can continue to unlock the secrets of iXEN cells, we may be able to improve induced pluripotent stem cell quality and lay the groundwork for future research on tissues that protect and nourish the human embryo.”

Normally the discovery of anything new, particularly when it over turns a long-held belief, is met with a degree of healthy skepticism at first. In science that’s a good thing. We all remember the eager way that STAP stem cells were hailed by many as a new way to create pluripotent stem cells until the research was discredited. But so far the Twitterverse and media outlets seems to share in the excitement about this discovery.