CIRM-Funded Scientists Test Recipe for Building New Muscles

When muscles get damaged due to disease or injury, the body activates its reserves—muscle stem cells that head to the injury site and mature into fully functioning muscle cells. But when the reserves are all used up, things get tricky.

Scientists at Sanford-Burnham may have uncovered the key to muscle repair.

Scientists at Sanford-Burnham may have uncovered the key to muscle repair.

This is especially the case for people living with muscle diseases, such as muscular dystrophy, in which the muscle degrades at a far faster rate than average and the body’s reserve stem cell supply becomes exhausted. With no more supply from which to draw new muscle cells, the muscles degrade further, resulting in the disease’s debilitating symptoms, such as progressive difficulty walking, running or speaking.

So, scientists have long tried to find a way to replenish the dwindling supply of muscle stem cells (called ‘satellite cells’), thus slowing—or even halting—muscle decay.

And now, researchers at the Sanford-Burnham Medical Research Institute have found a way to tweak the normal cycle, and boost the production of muscle cells even when supplies appear to be diminished. These findings, reported in the latest issue of Nature Medicine, offer an alternative treatment for the millions of people suffering not only from muscular dystrophy, but also other diseases that result in muscle decay—such as some forms of cancer and age-related diseases.

In this study, Sanford-Burnham researchers found that introducing a particular protein, called a STAT3 inhibitor, into the cycle of muscle-cell regeneration could boost the production of muscle cells—even after multiple rounds of repair that would otherwise render regeneration virtually impossible.

The STAT3 inhibitor, as its name suggests, works by ‘inhibiting,’ or effectively neutralizing, another protein called STAT3. Normally, STAT3 gets switched on in response to muscle injury, setting in motion a series of steps that replenishes muscle cells.

In experiments first in animal models of muscular dystrophy—and next in human cells in a petri dish—the team decided to modify how STAT3 functions. Instead of keeping STAT3 active, as would normally occur, the team introduced the STAT3 inhibitor at specific times during the muscle regeneration process. And in so doing, noticed a significant boost in muscle cell production. As Dr. Alessandra Sacco, the study’s senior author, stated in a news release:

“We’ve discovered that by timing the inhibition of STAT3—like an ‘on/off’ light switch—we can transiently expand the satellite cell population followed by their differentiation into mature cells.”

This approach to spurring muscle regeneration, which was funded in part by a CIRM training grant, is not only innovative, but offers new hope to a disease for which treatments have offered little. As Dr. Vittorio Sartorelli, deputy scientific director of the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), stated:

“Currently, there is no cure to stop or reverse any form of muscle-wasting disorders—only medication and therapy that can slow the process. A treatment approach consisting of cyclic bursts of STAT3 inhibitors could potentially restore muscle mass and function in patients, and this would be a very significant breakthrough.”

Sacco and her colleagues are encouraged by these results, and plan to explore their findings in greater detail—hopefully moving towards clinical trials:

“Our next step is to see how long we can extend the cycling pattern, and test some of the STAT3 inhibitors currently in clinical trials for other indications such as cancer, as this could accelerate testing in humans.”

Body’s own Healing Powers Could be Harnessed to Regrow Muscle, Wake Forest Study Finds

Imagine being able to repair muscle that had been damaged in an injury, not by transplanting new muscle or even by transplanting cells, but rather simply by laying the necessary groundwork—and letting the body do the rest.

The ability for the human body to regenerate tissues lost to injury or disease may still be closer to science fiction than reality, but scientists at the Wake Forest Baptist Medical Center in Winston-Salem, North Carolina, have gotten us one big step closer.

Reporting in the latest issue of the journal Acta Biomaterialia, Dr. Sang Jin Lee and his research team describe their ingenious new method for regrowing damaged muscle tissue in laboratory rodents—by supercharging the body’s own natural restorative abilities. As Lee explained in a news release:

“Working to leverage the body’s own regenerative properties, we designed a muscle-specific scaffolding system that can actively participate in functional tissue regeneration. This is a proof-of-concept study that we hope can one day be applied to human patients.”

Normally, the body’s muscles—as well as the majority of organs—sit atop a biological ‘scaffold’ created by a matrix of molecules secreted by surrounding cells. This scaffold gives the organs and muscle their three-dimensional structure.

Scientists have identified a protein that may help spur 'in body' muscle regeneration.

Scientists have identified a protein that may help spur ‘in body’ muscle regeneration.

As of right now, if doctors want to replace damaged muscle they have one of two options: either surgically transfer a muscle segment from one part of the body to the other, or engineer replacement muscle tissue in the lab from a biopsy. Both methods, while doable, are not ideal. In the first, you are reducing the strength of the donor muscle; in the second, you have the added challenge of standardizing the engineered cells so that they will graft successfully.

So, Lee and his team focused on a third way: coaxing the body’s own supply of adult stem cells—which are tissue specific and normally used for general small-scale maintenance—to rebuild the damaged muscle from within. Said Lee:

“Our aim was to bypass the challenges of both of these techniques and to demonstrate the mobilization of muscle cells to a target-specific site for muscle regeneration.”

In this study, the researchers developed a method to do just that in the laboratory animals. First, they implanted a new cellular scaffold into the rodents’ legs. After several weeks, they removed the scaffold to see whether any cells had latched on of their own accord.

Interestingly, the team found that without any additional manipulation, the scaffold had developed a network of blood vessels within just four weeks after implanting. They also observed the presence of some early-stage muscle cells. What the researchers wanted to do next was find a way to boost what they already observed naturally.

To do so, they tested whether proteins—previously known to be involved in muscle development—could boost the speed and amount of recruitment of muscle stem cells to the scaffold.

After a series of experiments, they found a leading candidate: a protein called insulin-like growth factor 1, or IGF-1. And when they injected IGF-1 into the newly-implanted scaffolds the difference was remarkable. These scaffolds had about four times as many cells when compared to the plain scaffolds. As Lee explained:

“The protein effectively promoted cell recruitment and accelerated muscle regeneration.”

The real work now begins, added Lee, whose team will now take their research to larger animal models, such as pigs, to see whether their technique can work on a far grander scale.

Stem Cell Stories that Caught our Eye: A Zebrafish’s Stripes, Stem Cell Sound Waves and the Dangers of Stem Cell Tourism

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.

The zebrafish (Danio rerio) owes its name to a repeating pattern of blue stripes alternating with golden stripes. [Credit: MPI f. Developmental Biology/ P. Malhawar]

The zebrafish (Danio rerio) owes its name to a repeating pattern of blue stripes alternating with golden stripes. [Credit: MPI f. Developmental Biology/ P. Malhawar]

How the Zebrafish Got its Stripes. Scientists in Germany have identified the different pigment cells that emerge during embryonic development and that determine the signature-striped pattern on the skins of zebrafish—one of science’s most commonly studied model organisms. These results, published this week in the journal Science, will help researchers understand how patterns, from stripes to spots to everything in between, develop.

In the study, scientists at the Max Planck Institute for Developmental Biology mapped how three distinct pigment cells, called black cells, reflective silvery cells, and yellow cells emerge during development and arrange themselves into the characteristic stripes. While researchers knew these three cell types were involved in stripe formation, what they discovered here was that these cells form when the zebrafish is a mere embryo.

“We were surprised to observe such cell behaviors, as these were totally unexpected from what we knew about color pattern formation”, says Prateek Mahalwar, first author of the study, in a news release.

What most surprised the research team, according to the news release, was that the three cell types each travel across the embryo to form the skin from a different direction. According to Dr. Christiane Nüsslein-Volhard, the study’s senior author:

“These findings inform our way of thinking about color pattern formation in other fish, but also in animals which are not accessible to direct observation during development such as peacocks, tigers and zebras.”

Sound Waves Dispense Individual Stem Cells. It happens all the time in the lab: scientists need to isolate and study a single stem cell. The trick is, how best to do it. Many methods have been developed to achieve this goal, but now scientists at the Regenerative Medicine Institute (REMEDI) at NUI Galway and Irish start-up Poly-Pico Technologies Ltd. have pioneered the idea of using sound waves to isolate living stem cells, in this case from bone marrow, with what they call the Poly-Pico micro-drop dispensing device.

Poly-Pico Technologies Ltd., a start-up that was spun out from the University of Limerick in Ireland, has developed a device that uses sound energy to accurately dispense protein, antibodies and DNA at very low volumes. In this study, REMEDI scientists harnessed this same technology to dispense stem cells.

These results, while preliminary, could help improve our understanding of stem cell biology, as well as a number of additional applications. As Poly-Pico CEO Alan Crean commented in a news release:

“We are delighted to see this new technology opportunity emerge at the interface between biology and engineering. There are other exciting applications of Poly-Pico’s unique technology in, for example, drug screening and DNA amplification. Our objective here is to make our technology available to companies, and researchers, and add value to what they are doing. This is one example of such a success.”

The Dangers of Stem Cell Toursim. Finally, a story from ABC News Australia, in which they recount a woman’s terrifying encounter with an unproven stem cell technique.

In this story, Annie Levington, who has suffered from multiple scleoris (MS) since 2007, tells of her journey from Melbourne to Germany. She describes a frightening experience in which she paid $15,000 to have a stem cell transplant. But when she returned home to Australia, she saw no improvement in her MS—a neuroinflammatory disease that causes nerve cells to whither.

“They said I would feel the effects within the next three weeks to a year. And nothing – I had noticed nothing whatsoever. [My neurologist] sent me to a hematologist who checked my bloods and concluded there was no evidence whatsoever that I received a stem cell transplant.”

Sadly, Levington’s story is not unusual, though it is not as dreadful as other instances, in which patients have traveled thousands of miles to have treatments that not only don’t cure they condition—they actually cause deadly harm.

The reason that these unproven techniques are even being administered is based on a medical loophole that allows doctors to treat patients, both in Australia and overseas, with their own stem cells—even if that treatment is unsafe or unproven.

And while there have been some extreme cases of death or severe injury because of these treatments, experts warn that the most likely outcome of these untested treatments is similar to Levington’s—your health won’t improve, but your bank account will have dwindled.

Want to learn more about the dangers of stem cell tourism? Check out our Stem Cell Tourism Fact Sheet.

Disease in a Dish – That’s a Mouthful: Using Human Stem Cells to Find ALS Treatments

Saying “let’s put some shrimp on the barbie” will whet an Australian’s appetite for barbequed prawns but for an American it conjures up an odd image of placing shrimp on a Barbie doll. This sort of word play confusion doesn’t just happen across continents but also between scientists and the public.

Take “disease in a dish” for example. To a stem cell scientist, this phrase right away describes a powerful way to study human disease in the lab using a Nobel Prize winning technique called induced pluripotent stem cells (iPSC). But to a non-scientist it sounds like a scene from some disgusting sci-fi horror cooking show.

Our latest video Disease in a Dish: That’s a Mouthful takes a lighthearted approach to help clear up any head scratching over this phrase. Although it’s injected with humor, the video focuses on a dreadful disease: amyotrophic lateral sclerosis (ALS). Also known as Lou Gehrig’s disease, it’s a disorder in which nerve cells that control muscle movement die. There are no effective treatments and it’s always fatal, usually within 3 to 5 years after diagnosis.

To explain disease in a dish, the video summarizes a Science Translation Medicine publication of CIRM-funded research reported by the laboratory of Robert Baloh, M.D., Ph.D., director of Cedars-Sinai’s multidisciplinary ALS Program. In the study, skin cells from patients with an inherited form of ALS were used to create nerve cells in a petri dish that exhibit the same genetic defects found in the neurons of ALS patients. With this disease in a dish, the team identified a possible cause of the disease: the cells overproduce molecules causing a toxic buildup that affects neuron function. The researchers devised a way to block the toxic buildup, which may point to a new therapeutic strategy.

In a press release, Clive Svendsen, Ph.D., a co-author on the publication and director of the Cedars-Sinai Regenerative Medicine Institute had this perspective on the results:

“ALS may be the cruelest, most severe neurological disease, but I believe the stem cell approach used in this collaborative effort holds the key to unlocking the mysteries of this and other devastating disorders.”

The video is the pilot episode of Stem Cells in Your Face, which we hope will be an ongoing informational series that helps explain the latest advances toward stem cell-based therapies.

For more information about CIRM-funded ALS research, visit our ALS fact sheet.

Revealing the Invisible: Scientists Uncover the Secret Ingredient to Making Blood-Forming Stem Cells

They are among the most versatile types of stem cell types in the body. They live inside bone marrow and in the blood of the umbilical cord. They can be used to treat deadly cancers such as leukemia (Leukemia Fact Sheet) as well as many blood disorders. But no one really understood the details of how they were made.

How are blood stem cells made? Australian scientists have uncovered a missing ingredient.

How are blood stem cells made? Australian scientists have uncovered a missing ingredient.

That is, until scientists at the Australian Regenerative Medicine Institute devised an ingenious way to view the formation of these hematopoetic stem cells (HSC’s) in unprecedented detail. And in so doing, found the missing ingredient that may make it possible to grow fully functioning versions of these cells in the lab—opening the door to treating a wide range of blood and immune disorders. Attempts to grow these in the past have resulted in immature versions more like those found in a fetus than those in an adult.

One of the study’s senior authors, Dr. Peter Currie, even goes so far as to say this discovery represents a ‘Holy Grail’ for the field. As he explained in today’s news release:

“HSCs are one of the best therapeutic tools at our disposal because they can make any blood cell in the body. Potentially we could use these cells in may more ways than current transplantation strategies to treat serious blood disorders and diseases, but only if we can figure out how they are generated in the first place.”

Fortunately, this new study—published today in the journal Nature—brings researchers closer to that goal.

Using high-resolution microscopic imaging techniques, Currie and his team filmed the development of a zebra fish embryo—with a particular focus on HSCs. When they played back the video, the team saw something that no one had noticed before. In order for HSCs to develop properly, they needed a little support from another cell type known as endotomes. As Currie explained:

“Endotome cells act like a comfy sofa for pre-HSCs to snuggle into, helping them progress to become fully fledged [HSCs]. Not only did we identify some of the cells and signals required for HSC formation, we also pinpointed the genes required for endotome formation in the first place.”

It appears that this unique relationship between endotomes and HSCs is key to HSC formation, a process that had for so long evaded researchers. But armed with this newfound knowledge, the team could one day produce different types of blood cells ‘on demand’—and potentially treat many types of blood disorders. This has been such a tough nut to crack with such great potential CIRM convened an international panel of experts to produce a whitepaper on the issue.

The team’s immediate next steps, according to Currie, are to pinpoint the molecular switches themselves (within endotomes and HSCs) that trigger the production of these stem cells. And while these results are preliminary, he is cautiously optimistic about the potential power to treat a variety of illnesses:

“Potentially, it’s imaginable that you could even correct genetic defects in cells and then transplant them back into the body.”

Breast Cancer Commandeers Mammary Stem Cells for Own, Nefarious Purposes

Most instances of breast cancer happen later in life—often after menopause. In many cases, the cancer progresses slowly, over a period of months or even years, often giving physicians precious time to implement a treatment plan, successfully battling that cancer into remission.

A section from a mammary 'outgrowth' harvested at lactation. [Credit: UC San Diego School of Medicine]

A section from a mammary ‘outgrowth’ harvested at lactation. [Credit: UC San Diego School of Medicine]

But there is another far more aggressive form of breast cancer that tends to develop earlier, often immediately following pregnancy. And now, researchers at the University of California, San Diego (UCSD) have discovered how this form of cancer hijacks a woman’s own stem cells to grow quickly and spread throughout the body.

Reporting in the latest issue of the journal Developmental Cell, UCSD stem cell researchers Drs. David Cheresh and Jay Desgrosellier and their teams have found a link between the molecular signaling switches that spur this aggressive, post-pregnancy breast cancer—and mammary stem cells that are normally activated during pregnancy.

These findings, say Cheresh, offer key insight into how scientists may develop better treatments for this form of breast cancer. As he stated in a news release:

“By understanding a fundamental mechanism of mammary gland development during pregnancy, we have gained a rare insight into how aggressive breast cancer might be treated.”

Normally, pregnancy activates a special group of stem cells in the mammary gland. Their job is to ready the expectant mother for feeding the newborn baby. By the time the baby is born, however, these stem cells go back into hibernation.

However, in some women, these mammary stem cells get hijacked by cancer cells. Rather than the mammary stem cells shutting down by the time milk production begins, cancer cells keep them switched on—which then contributes to the progression of cancer.

These findings shed much-needed light on the complex relationship between breast cancer and pregnancy. However, the authors caution that these findings don’t imply that becoming pregnant causes breast cancer. Rather, as Cheresh explained:

“Our work doesn’t speak to the actual cause of cancer. Rather, it explains what can happen once cancer has been initiated.”

Cheresh, who has received CIRM support for related work, has pinpointed a protein called CD61 that may promote the progression of breast cancer. CD61 has already been implicated in cancer metastasis and resistance to cancer drugs, so it makes sense that it would play a role in breast cancer as well.

Importantly, the discovery of a potential connection between CD61 and this form of breast cancer may ultimately open up new avenues for treating this type of cancer more successfully.

“Detecting CD61 might help doctors determine what kind of therapeutic approach to use, knowing that they might be dealing with a more aggressive yet treatable form of breast cancer. For example, there are existing drugs that block CD61 signaling, which might be another potential aspect of treatment.”

Want to learn more about breast cancer and stem cells? Check out our Solid Tumor Fact Sheet.