Family ties help drive UCLA’s search for a stem cell treatment for Duchenne muscular dystrophy

Duchenne

April Pyle, Courtney Young and Melissa Spencer: Photo courtesy UCLA Broad Stem Cell Research Center

People get into science for all sorts of different reasons. For Courtney Young the reason was easy; she has a cousin with Duchenne muscular dystrophy.

Now her work as part of a team at UCLA has led to a new approach that could eventually help many of those suffering from Duchenne, the most common fatal childhood genetic disease.

The disease, which usually affects boys, leads to progressive muscle weakness, which means children may lose their ability to walk by age 12 and eventually results in breathing difficulties and heart disease.

Duchenne is caused by a defective gene, which leads to very low levels of a protein called dystrophin – an important element in building strong, healthy muscles. There are many sections of the gene where this defect or mutation can be found, but in 60 percent of cases it occurs within one particular hot spot of DNA. That’s the area that the UCLA team focused on, helped in part by a grant from CIRM.

Skin in the game

First they obtained skin cells from people with Duchenne muscular dystrophy and turned those into iPS cells. Those cells have the ability to become any other cell in the body and, just as importantly for this research, still retain the genetic code from the person they came from. In this case it meant they still had the genetic defect that led to Duchenne muscular dystrophy.

Then the researchers used a gene editing tool called CRISPR (we’ve written about this a lot in the past, you can a couple of those articles  here and here  and here)  to remove the genetic mutations that cause Duchenne. They then turned those iPS cells into skeletal muscle cells and transplanted them into mice that had the genetic mutation that meant they couldn’t produce dystrophin.

To their delight they found that the transplanted cells produced dystrophin in the mice.

Breaking new ground

April Pyle, a co-senior author of the study, which appears in the journal Cell Stem Cell,  said, in a news release, this was the first study to use human iPS cells to correct the problem in muscle tissue caused by Duchenne:

“This work demonstrates the feasibility of using a single gene editing platform, plus the regenerative power of stem cells to correct genetic mutations and restore dystrophin production for 60 percent of Duchenne patients.”

The researchers say this is an important step towards developing a new treatment for Duchenne muscular dystrophy, but caution there are still many years of work before this approach will be ready to test in people.

For Courtney Young advancing the science is not just professionally gratifying, it’s also personally satisfying:

“I already knew I was interested in science, so after my cousin’s diagnosis, I decided to dedicate my career to finding a cure for Duchenne. It makes everything a lot more meaningful, knowing that I’m doing something to help all the boys who will come after my cousin. I feel like I’m contributing and I’m excited because the field of Duchenne research is advancing in a really positive direction.”

 

 

The key to unlocking stem cell’s potential and blocking a deadly threat

A small slice of who you are - brain cells made from embryonic stem cells.

A small slice of who you are – brain cells made from embryonic stem cells.

Our bodies are amazingly complex systems. By some estimates there are more than 37 trillion cells in our bodies.  That’s trillion with a “t”. Each of those cells engages in some form of communication and signaling with other cells which makes our bodies one heck of a busy place to be.

Yet all this activity may owe much of its splendor and complexity to a relatively small number of starting materials. Key among those may be one protein which seems to act like a “master switch” and can determine if a cell changes and multiplies, or just stays the same.

Starting out

But let’s begin at the beginning. We all start out as a single fertilized egg that develops into embryonic stem cells, which in turn become adult stem cells, which then give rise to all the different cells and tissues and structures in our body – such as our bones and brains and blood.

But how do those cells know when to change, what to change into, and when to stop? Change too little and something is undeveloped. Change too much and you risk the kind of explosive uncontrolled multiplication of cells that you see in cancer.

So, clearly, knowing what controls those changes in stem cells, and learning how to use it, could have an enormous impact on our ability to use stem cells to treat a wide range of diseases.

What’s in a name, or a number

Now researchers at Mount Sinai have identified a single protein that appears to play a major role in this control process. The protein is called zinc finger protein 217 (ZFP217) and it controls the actions of genes that in turn control whether a cell changes into another kind of cell and how often it keeps dividing and multiplying.

The study is published in Cell Stem Cell  and there is some pretty complex science involved but ultimately what it boils down to is that ZFP217 has an impact on m6A (scientists really need to start coming up with more imaginative names) which is a protein that helps determine if a gene is turned on or off. If turned on the gene performs one function. If turned off it doesn’t.

By, in effect, blocking the action of m6A, ZFP217 is able to stop the process that would allow stem cells to differentiate, or change, into other cells and also ends their ability to keep renewing themselves.

But wait, there’s more!

One other important role that ZFP217 plays is in helping spur the growth of cancerous tumors. Too much of the protein allows these cells to multiply in an unlimited and uncontrolled fashion, typical of the kind of growth we see in tumors.

The study was done in mice but in a news release  the lead study author, Martin Walsh, PhD, talked about the possible significance of the findings for people:

“The hope is that ZFP217 could be used to maintain supplies of therapeutic stem cells. At the same time, as the human ZPF217 is associated with poor survival in a variety of cancers, understanding how this protein operates in physiological conditions may help to predict cancer risk, achieve earlier diagnosis and provide novel therapeutic approaches.”

Having a deeper understanding of what makes some stem cells multiply and change into other cells could enable researchers to better use stem cells to develop new approaches to treating some of the most intractable diseases of our time.

If that happens then ZFP217 might be a name to remember after all.

Skipping a Step: Turning Brain Cells Directly into Neurons

It was once commonly believed that “what you see is what you get” with the human brain. As in, the brains cells that you are born with are the only ones you’ll have for the rest of your life because they can’t regenerate.

The discovery of brain stem cells in the late 90s disproved this notion and established that the brain can replace old cells and repair damage after injury. The brain’s regenerative capacity is limited, however. Consequently, patients suffering from neurodegenerative diseases like Alzheimer’s and Parkinson’s can’t rely on their brain stem cells to repopulate all of the sick and dying neurons in their brains.

This is where cellular reprogramming technology could come to the rescue. Induced pluripotent stem cells (iPSCs) generated from patient skin cells by cellular reprogramming can be turned into many types of brain cells to study diseases in a petri dish, as well as to test drugs and develop stem cell therapies. Eventually, the hope is to transplant iPSC-derived brain cells back into patient brains to treat or cure degenerative diseases.

Making neurons directly from other brain cells

Another form of cellular reprogramming, offers a more direct approach to generating populations of healthy brain cells. Using a similar technique to iPSCs, scientists can use specific factors to directly reprogram skin cells or other brain cells into neurons without making them go through the pluripotent stem cell state. By skipping a step in the reprogramming process, researchers save time, money, and energy – and it could result in safer cells.

The group used small molecules to directly reprogram human astrocytes into neurons that could be transplanted into mice. (Zhang et al., 2015)

The group used small molecules to directly reprogram human astrocytes into neurons that could be transplanted into mice. (Zhang et al., 2015)

While direct reprogramming of skin and non-neuronal brain cells into neurons has been published before, a study in Cell Stem Cell by a group at Penn State University last week described a new-and-improved method to make properly functioning neurons from brain astrocytes. Astrocytes are a type of glial cell that are abundant in the brain. They provide neurons with support, nutrients, and aid following injury.

Led by senior author Gong Chen, the group bathed human astrocytes in a cocktail of small molecules that turned the astrocytes into neurons in less than 10 days. These neurons survived in a dish for more than 5 months and were able to send electrical signals to each other (a sign that they were functional). Even more exciting was that the directly reprogrammed neurons survived and functioned properly when they were transplanted into the brains of mice.

When they studied the biological mechanism behind their direct reprogramming method, they found that the small molecule cocktail turned off the activity of astrocyte-specific genes in the astrocytes and turned on neuron-specific genes to convert them into neurons.

Human astrocytes (left) were directly reprogrammed into neurons (right). (Zhang et al., 2015)

Human astrocytes (left) were directly reprogrammed into neurons (right). (Zhang et al., 2015)

This discovery is great news for the reprogramming field as using small molecule reprogramming instead of the commonly used transcription-factor based reprogramming (which involves using viruses that can damage or alter the genome) is a more attractive method with broader applications­ for making neurons that can be transplanted into humans.

Direct reprogramming makes new neurons in the brain

But wait, there’s more! An article from TheScientist reported that multiple groups at the Society for Neuroscience (SFN) conference  in Chicago presented results on directly converting glial cells into neurons in mouse brains rather than in a dish.

One group from the Johannes Gutenberg University used two transcription factors, proteins that control which genes are turned on or off in the human genome, to directly reprogram mouse astrocytes into neurons. By producing more of Sox2 and Ascl1 in the cortex of the mouse brain than would normally be found there, they were able to turn 15% of the glial cells in that area into neurons.

The function of these directly reprogrammed neurons remains to be determined, but the lead scientist, Sophie Peron, told TheScientist:

“That’s the next step. Now that we have a system to get these cells converted we are currently studying their connectivity, functionality, and precise characteristics.”

Two other groups also reported similar findings when they worked with a type of glial cell called reactive astrocytes. These cells are specifically activated during injury to jumpstart the healing process. The first group from the University of Texas Southwestern used the factor Sox2 to directly reprogram reactive astrocytes into neurons in mice, while the group from Penn State University – mentioned earlier in this blog – did the same thing, but using a different factor, NeuroD1.

The Penn State group went further to test their direct reprogramming method in a mouse model of stroke and found that NeuroD1-reprogrammed neurons reduced cell death and tissue scarring after stroke.

Lead scientist Yuchen Chen said:

“These findings suggest that direct reprogramming of glial cells into functional neurons may provide a completely new approach for brain repair after stroke. Our next step is to analyze whether the glia-neuron conversion technology can facilitate functional recovery in stroke animals.”


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Happy Stem Cell Awareness Day!

SCAD_Logo_2015I woke up today extra early this morning feeling like a kid at Christmas time because it’s Stem Cell Awareness day!

This exciting day brings together organizations and people around the world working to ensure that we realize the benefits of one of the most promising fields of science in our time. The day is a unique global opportunity to foster greater understanding about stem cell research and the range of potential applications for disease and injury.

For the millions of people around the world who suffer from incurable diseases and injury, Stem Cell Awareness Day is a day to celebrate the scientific advances made to-date and be hopeful of what is yet to come.

Institutions and scientists around the world will be participating in talks and activities that celebrate and also educate the community about stem cell research. For a list of events, check out our Stem Cell Awareness Day webpage. You can also follow other events on twitter by following the hashtags #stemcellday and #astemcellscientistbecause.

In celebration of this exciting day, the Stem Cellar team would like to highlight a few videos and webpages dedicated to stem cell awareness. Enjoy!

Videos:

“A Stem Cell Story” from our friends at EuroStemCell

#AStemCellScientistBecause videos via Cell Stem Cell on twitter

 

Stem Cell Awareness Webpages:

What’s Fat Got to do With Alzheimer’s?

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(Image credit: FineCooking.com)

Diets these days are a dime a dozen, and dietary trends come and go. First eggs were “out” because they contain cholesterol, but now they are back “in” because we now know that some types of cholesterol can be actually good for the body. Then there was the era of “fat-free” or “reduced-fat” foods. This was all the rage in the 90s until scientists realized that eliminating healthy fats from your diet can have negative consequences on your health.

The theories behind different diets evolve constantly much like the theories behind complicated neurodegenerative diseases like Alzheimer’s disease (AD). Alzheimer’s is a debilitating disease that slowly robs patients of their minds, leaving them as shadows of their former selves. AD affects 47.5 million people globally with 7.7 million new patients diagnosed every year, thus making the disease one of the most important unmet medical needs to be addressed.

The causes of AD have eluded scientists for over a century. However, the main theory behind what causes AD involves the buildup of toxic proteins in the brain. These proteins accumulate to form structures called plaques and tangles that impair brain function and kill off brain cells.

Unfortunately, there is no cure for AD or treatments to stop its progression. This sobering fact is not due to a lack of effort by scientists and pharmaceutical companies. Dozens of drug therapies have or are being tested in clinical trials, many of them focusing on the removal of toxic protein levels in people with the disease. While there have been some pretty dramatic failures in these trials, a few are starting to show encouraging results.

Link Between Abnormal Fat Metabolism and Alzheimer’s Disease

Now, a new theory on AD involving the build up of toxic fat molecules in the brains of AD patients has been thrown into the mix. In a study published Thursday in Cell Stem Cell, scientists from Montreal reported the presence of fat droplets in AD patient brains in areas surrounding brain stem cells. Brain stem cells are responsible for growing new brain cells (such as nerves) and maintaining overall brain function and health. The scientists discovered that the fat droplets actually prevented the regenerative abilities of the brain stem cells, leading them to believe that the accumulation of fat droplets in the brain could be a cause of AD.

Fat is used as an energy source by cells and organs in the body in a process called “fatty acid metabolism”. Fat metabolism is very important for proper brain development but also in maintaining brain health and function in adults. Problems with fat metabolism in humans can cause diseases such as obesity, diabetes, and heart disease. So one can imagine that problems with fat metabolism in the brain could also have serious consequences.

In this study, scientists used a genetic mouse model of AD that had a “triple-threat” of genetic mutations that cause AD in humans. They studied the brain stem cells in these mice and found that the support cells surrounding the stem cells were full of fat droplets. They also noticed that when the fat droplets were present, the brain stem cells were not dividing to generate new brain cells (which is a common defect associated with AD). When they looked at brain tissue from nine AD patients, they also observed a similar pattern of an increased concentration of fat droplets surrounding areas of brain stem cells compared to healthy human brain tissue.

fat droplets

AD patient brains (lower panel) have more fat droplets shown in red than normal healthy brains (upper panel). (Hamilton et al., 2015)

Using a fancy science technique called mass spectrometry, the scientists found that the fat droplets were made up of a fat triglyceride called oleic acid, which is a common component of vegetable and animal fats. To prove that oleic acid was bad for brain stem cells, they took normal healthy mice and injected oleic acid into their brains. They observed that adding this fat negatively affected the stem cells’ regenerative ability to divide. Going one step further, the scientists used drugs to block the formation of oleic acid in their AD mouse model, and saw that removing this fat allowed the brain stem cells to divide and function properly.

The major conclusions generated from this study were summarized nicely by senior author Karl Fernandes in a news release:

We discovered that these fatty acids are produced by the brain, that they build up slowly with normal aging, but that the process is accelerated significantly in the presence of genes that predispose to Alzheimer’s disease. In mice predisposed to the disease, we showed that these fatty acids accumulate very early on, at two months of age, which corresponds to the early twenties in humans. Therefore, we think that the build-up of fatty acids is not a consequence but rather a cause or accelerator of the disease.

 

Don’t Count Your Chickens Just Yet

While this study suggests that fat accumulation in the brain is a cause of AD, more research will need to be done to confirm that abnormal fat metabolism is the culprit. Some experiments can be done quickly such as treating their AD mouse model with the drugs that block the formation of the “bad fat” and monitoring them for an extended time period to see if blocking oleic acid accumulation prevents the onset of AD symptoms like memory loss. Other experiments, such as therapeutically targeting abnormal brain fat deposits in human, will be more long term projects with unknown results.

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Dr. Alois Alzheimer

Nontheless, this study nicely ties back to an observation by Dr. Alois Alzheimer who first reported about AD in 1906 . When he dissected the brains of AD patients who had passed away, he found five major pathologies that distinguished their brains from healthy brains. One of these traits was an increased concentration of fat droplets. Thus findings from Fernandes and his group revive a century old notion that fat metabolism could be a cause of AD and open doors for the development of new therapeutic strategies to fight AD.


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Policy Matters: Stem Cells and the Public Interest

Guest Author Geoff Lomax is CIRM’s Senior Officer for Medical and Ethical Standards.

In the spirit of Stem Cell Awareness Day, Cell Stem Cell has compiled a “Public Interest” collection of articles covering ethical, legal, and social implications of stem cell research and made it freely available. The collection may be found here.

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The collection covers issues ranging from research involving human embryos to the use of stem cell therapies in patients. For those of you interested in a good primer on the history of stem cell controversies, Herbert Gottweis provides a detailed review of the federal policy debate in the United States. This debate has resulted in inconsistent policy and disrupted research. Gottweis uses this history to support his message that a “comprehensive, and proactive policy approach in this field beyond the quick legal fix” is needed for patients to ultimately benefit from the science.

What I found most interesting about this collection was the focus on stem cell treatments and “tourism.” A majority of the articles address the use of stem cells in patients. This focus is an indicator of how far the field has progressed. Stem cells clinical trials are now a reality and this results in two separated but related considerations. First, is how to make sure prospective patients are well informed should they participate in a clinical trial. Second, how to avoid stem cell “snake oil” where someone is pitching an unproven procedure. These issues are related by their solution that involves empowerment and education of patients and their support networks.

For example, in Stem Cell Tourism and Public Education: The Missing Elements, Master writes:

“It is important for the scientific, medical, ethics, and policy communities to continue to promote accurate patient and public information on stem cell research and tourism and to ensure that it is effectively disseminated to patients by working alongside patient advocacy groups.”

Master’s team found that groups committed to the advancement of good science, including patient advocates and researchers, often lacked basic information about clinical trials and other options for patients. This lack of information may contribute to patients being wooed by those pitching unproven procedures. Thus, the research community should continue to work with patients and advocacy organizations to identity options for treatment.

Another aspect of patient empowerment is what Insoo Huyn refers to as “therapeutic hope” in his piece: Therapeutic Hope, Spiritual Distress, and the Problem of Stem Cell Tourism. Huyn suggests that a supportive system for delivering cell therapies should includes nurturing hope. He writes, “patients might understand when an intervention’s chances of success are extremely remote at best, but may still want to ‘‘give it a shot’’ as long as a beneficial outcome cannot be ruled out as categorically impossible.” Huyn recognizes that well developed early-stage clinical trials are not expected to provide a benefit to patients (they are designed to evaluate safety), but the nature of the therapeutic (often cells) means there may be some real effect.

A third piece by the ISSCR Ethics Taskforce titled Patients Beware: Commercialized Stem Cell Treatments on the Web presents a guide to evaluating therapies. They present five principles that patients, researchers and advocates can rally around to identify credible interventions. The taskforce states:

The guiding principles for the development of the recommended process were that (1) the standards for identifying and reviewing clinics and suppliers should be objective and clear; (2) the inquiry and review process should be publicly transparent and relatively straight- forward for any clinic or practitioner to comply with; (3) conflicts of interest, if any, of the declarant ought to be disclosed to the ISSCR; (4) there should be no actual or apparent conflicts of interest of staff or others involved in the inquiry or review process for any particular matter; and (5) any findings that a clinic fails to meet standards should be communicated in a specific factual way, rather than with broad conclusions of fraudulent practices.

While the Cell Stem Cell Public Interest series covers a range of issues related to stem cells and society, the emphasis on treatments and patients is a reminder of how far the field has come. There is broad consensus that patients, researchers and advocates have roles to play in advancing safe and effective cell therapies.

Geoff Lomax