muscle

Repairing damaged muscles

/ Kevin McCormack / 3 Comments
Close-up of the arm of a 70-year-old male patient with a torn biceps muscle as a result of a bowling injury; Photo courtesy Science Photo Library

In the time of coronavirus an awful lot of people are not just working from home they’re also working out at home. That’s a good thing; exercise is a great way to boost the immune system, stay healthy and deal with stress. But for people used to more structured workouts at the gym it can come with a downside. Trying new routines at home that look easy on YouTube, but are harder in practice could potentially increase the risk of injury.

A new study from Japan looks at what happens when you damage a muscle. It won’t help it heal faster, but it will at least let you understand what is happening inside your body as you sit there with ice on your arm and ibuprofen in your hand.

The researchers found that when you damage a muscle, for example by trying to lift too much weight or doing too many repetitions of one exercise, the damaged muscle fibers leak substances that activate nearby “satellite” stem cells. These satellite cells then flock to the site of the injury and help repair the muscle.

The team, from Kumamoto University and Nagasaki University in Japan, named the leaking substances “Damaged myofiber-derived factors” (DMDFs) – personally I think “Substances Leaked by Injured Muscles (SLIM) would be a much cooler acronym, but that’s just me. Gaining a deeper understanding of how DMDFs work might help lead to therapies for older people who have fewer satellite muscle cells, and also for conditions like muscular dystrophy and age-related muscular fragility (sarcopenia), where the number and function of satellite cells decreases.

In an article in Science Daily, Professor Yusuke Ono, the leader of the study, says it’s possible that DMDFs play an even greater role in the body:

“In this study, we proposed a new muscle injury-regeneration model. However, the detailed molecular mechanism of how DMDFs activate satellite cells remains an unclear issue for future research. In addition to satellite cell activation, DMDF moonlighting functions are expected to be diverse. Recent studies have shown that skeletal muscle secretes various factors that affect other organs and tissues, such as the brain and fat, into the bloodstream, so it may be possible that DMDFs are involved in the linkage between injured muscle and other organs via blood circulation. We believe that further elucidation of the functions of DMDFs could clarify the pathologies of some muscle diseases and help in the development of new drugs.”

The study appears in the journal Stem Cell Reports.

From organs to muscle tissue: how stem cells are being used in 3D

/ Yimy Villa / Leave a comment
A Sunday Afternoon on the Island of La Grande Jatte by Georges-Pierre Seurat

When most people think of stem cells, they might conjure up an image of small dots under a microscope. It is hard to imagine these small specs being applied to three-dimensional structures. But like a pointillism painting, such as A Sunday Afternoon on the Island of La Grande Jatte by Georges-Pierre Seurat, stem cells can be used to help build things never thought possible. Two studies demonstrate this concept in very different ways.

MIT engineers have designed coiled “nanoyarn,” shown as an artist’s interpretation here. The twisted fibers are lined with living cells and may be used to repair injured muscles and tendons while maintaining their flexibility. Image by Felice Frankel

A study at MIT used nanofiber coated with muscle stem cells and mesenchymal stem cells in an effort to provide a flexible range of motion for these stem cells. Hundreds of thousands of nanofibers were twisted, resembling yarn and rope, in order to mimic the pattern found in tendons and muscle tissue throughout the body. The researchers at MIT found that the yarn like structure of the nanofibers keep the stem cells alive and growing, even as the team stretched and bent the fibers multiple times.

Normally, when a person injures these types of tissues, particularly around a major joint such as the shoulder or knee, it require surgery and weeks of limited mobility to heal properly. The MIT team hopes that their technology could be applied toward treating the site of injury while maintaining range of motion as the newly applied stem cells continue to grow to replace the injured tissue.

In an article, Dr. Ming Guo, assistant professor of mechanical engineering at MIT and one of the authors of the study, was quoted as saying,

“When you repair muscle or tendon, you really have to fix their movement for a period of time, by wearing a boot, for example. With this nanofiber yarn, the hope is, you won’t have to wearing anything like that.”

Their complete findings were published in the Proceedings of the National Academy of Sciences (PNAS).

Researchers in Germany have created transparent human organs using a new technology that could pave the way to print three-dimensional body parts such as kidneys for transplants. Above, Dr. Ali Ertuerk inspects a transparent human brain.
Photo courtesy of Reuters.

In a separate study, researchers in Germany have successfully created transparent human organs, paving the way to print three-dimensional body parts. Dr. Ali Erturk at Ludwig Maximilians University in Munich, with a team of scientists, developed a technique to create a detailed blueprint of organs, including blood vessels and every single cell in its specific location. These directions were then used to print a scaffold of the organ. With the help of a 3D printer, stem cells, acting like ink in a printer, were injected into the correct positions to make the organ functional.

Previously, 3D-printed organs lacked detailed cellular structures because they were based on crude images from computer tomography or MRI machines. This technology has now changed that.

In an article, Dr. Erturk is quoted as saying,

“We can see where every single cell is located in transparent human organs. And then we can actually replicate exactly the same, using 3D bioprinting technology to make a real functional organ. Therefore, I believe we are much closer to a real human organ for the first time now.”

Have scientists discovered a natural way to boost muscle regeneration?

/ Karen Ring / 4 Comments

Painkillers like ibuprofen and aspirin are often a part of an athlete’s post-exercise regimen after intense workouts. Sore muscles, aches and stiffness can be more manageable by taking these drugs – collectively called non-steroidal anti-inflammatory drugs, or NSAIDS – to reduce inflammation and pain. But research suggests that the anti-inflammatory effects of these painkillers might cause more harm than good by preventing muscle repair and regeneration after injury or exercise.

A new study out of Stanford Medicine supports these findings and proposes that a component of the inflammatory process is necessary to promote muscle regeneration. Their study was funded in part by a CIRM grant and was published this week in the Proceedings of the National Academy of Sciences.

Muscle stem cells are scattered throughout skeletal muscle tissue and remain inactive until they are stimulated to divide. When muscles are damaged or injured, an inflammatory response involving a cascade of immune cells, molecules and growth factors activates these stem cells, prompting them to regenerate muscle tissue.

Andrew Ho, Helen Blau and Adelaida Palla led a study that found drugs like aspirin and ibuprofen can inhibit the ability of muscle tissue to repair itself in mice. (Image credit: Scott Reiff)

The Stanford team discovered that a molecule called Prostaglandin E2 or PGE2 is released during the inflammatory response and stimulates muscle repair by directly targeting the EP4 receptor on the surface of muscle stem cells. The interaction between PGE2 and EP4 causes muscle stem cells to divide and robustly regenerate muscle tissue.

Senior author on the study, Dr. Helen Blau, explained her team’s interest in PGE2-mediated muscle repair in a news release,

“Traditionally, inflammation has been considered a natural, but sometimes harmful, response to injury. But we wondered whether there might be a component in the pro-inflammatory signaling cascade that also stimulated muscle repair. We found that a single exposure to prostaglandin E2 has a profound effect on the proliferation of muscle stem cells in living animals. We postulated that we could enhance muscle regeneration by simply augmenting this natural physiological process in existing stem cells already located along the muscle fiber.”

Further studies in mice revealed that injury increased PGE2 levels in muscle tissue and increased expression of the EP4 receptor on muscle stem cells. This gave the authors the idea that treating mice with a pulse of PGE2 could stimulate their muscle stem cells to regenerate muscle tissue.

Their hunch turned out to be right. Co-first author Dr. Adelaida Palla explained,

“When we gave mice a single shot of PGE2 directly to the muscle, it robustly affected muscle regeneration and even increased strength. Conversely, if we inhibited the ability of the muscle stem cells to respond to naturally produced PGE2 by blocking the expression of EP4 or by giving them a single dose of a nonsteroidal anti-inflammatory drug to suppress PGE2 production, the acquisition of strength was impeded.”

Their research not only adds more evidence against the using NSAID painkillers like ibuprofen and aspirin to treat sore muscles, but also suggests that PGE2 could be a natural therapeutic strategy to boost muscle regeneration.

This cross-section of regenerated muscle shows muscle stem cells (red) in their niche along the muscle fibers (green). (Photo courtesy of Blau lab)

PGE2 is already approved by the US Food and Drug Administration (FDA) to induce labor in pregnant women, and Dr. Blau hopes that further research in her lab will pave the way for repurposing PGE2 to treat muscle injury and other conditions.

“Our goal has always been to find regulators of human muscle stem cells that can be useful in regenerative medicine. It might be possible to repurpose this already FDA-approved drug for use in muscle. This could be a novel way to target existing stem cells in their native environment to help people with muscle injury or trauma, or even to combat natural aging.”

Stem Cell Stories That Caught our Eye: Making blood and muscle from stem cells and helping students realize their “pluripotential”

/ Karen Ring / Leave a comment

Stem cells offer new drug for blood diseases. A new treatment for blood disorders might be in the works thanks to a stem cell-based study out of Harvard Medical School and Boston Children’s hospital. Their study was published in the journal Science Translational Medicine.

The teams made induced pluripotent stem cells (iPSCs) from the skin of patients with a rare blood disorder called Diamond-Blackfan anemia (DBA) – a bone marrow disease that prevents new blood cells from forming. iPSCs from DBA patients were then specialized into blood progenitor cells, the precursors to blood cells. However, these precursor cells were incapable of forming red blood cells in a dish like normal precursors do.

Red blood cells were successfully made via induced pluripotent stem cells from a Diamond-Blackfan anemia patient. Image: Daley lab, Boston Children’s

Red blood cells were successfully made via induced pluripotent stem cells from a Diamond-Blackfan anemia patient. Image: Daley lab, Boston Children’s

The blood progenitor cells from DBA patients were then used to screen a library of compounds to identify drugs that could get the DBA progenitor cells to develop into red blood cells. They found a compound called SMER28 that had this very effect on progenitor cells in a dish. When the compound was tested in zebrafish and mouse models of DBA, the researchers observed an increase in red blood cell production and a reduction of anemia symptoms.

Getting pluripotent stem cells like iPSCs to turn into blood progenitor cells and expand these cells into a population large enough for drug screening has not been an easy task for stem cell researchers.

Co-first author on the study, Sergei Doulatov, explained in a press release, “iPS cells have been hard to instruct when it comes to making blood. This is the first time iPS cells have been used to identify a drug to treat a blood disorder.”

In the future, the researchers will pursue the questions of why and how SMER28 boosts red blood cell generation. Further work will be done to determine whether this drug will be a useful treatment for DBA patients and other blood disorders.

 

Students realize their “pluripotential”. In last week’s stem cell stories, I gave a preview about an exciting stem cell “Day of Discovery” hosted by USC Stem Cell in southern California. The event happened this past Saturday. Over 500 local middle and high school students attended the event and participated in lab tours, poster sessions, and a career resource fair. Throughout the day, they were engaged by scientists and educators about stem cell science through interactive games, including the stem cell edition of Family Feud and a stem cell smartphone videogame developed by USC graduate students.

In a USC press release, Rohit Varma, dean of the Keck School of Medicine of USC, emphasized the importance of exposing young students to research and scientific careers.

“It was a true joy to welcome the middle and high school students from our neighboring communities in Boyle Heights, El Sereno, Lincoln Heights, the San Gabriel Valley and throughout Los Angeles. This bright young generation brings tremendous potential to their future pursuits in biotechnology and beyond.”

Maria Elena Kennedy, a consultant to the Bassett Unified School District, added, “The exposure to the Keck School of Medicine of USC is invaluable for the students. Our students come from a Title I School District, and they don’t often have the opportunity to come to a campus like the Keck School of Medicine.”

The day was a huge success with students posting photos of their experiences on social media and enthusiastically writing messages like “stem cells are our future” and “USC is my goal”. One high school student acknowledged the opportunity that this day offers to students, “California currently has biotechnology as the biggest growing sector. Right now, it’s really important that students are visiting labs and learning more about the industry, so they can potentially see where they’re going with their lives and careers.”

You can read more about USC’s Stem Cell Day of Discovery here. Below are a few pictures from the event courtesy of David Sprague and USC.

Students have fun with robots representing osteoblast and osteoclast cells at the Stem Cell Day of Discovery event held at the USC Health Sciences Campus in Los Angeles, CA. February 4th, 2017. The event encourages students to learn more about STEM opportunities, including stem cell study and biotech, and helps demystify the fields and encourage student engagement. Photo by David Sprague

Students have fun with robots representing osteoblast and osteoclast cells at the USC Stem Cell Day of Discovery. Photo by David Sprague

Dr. Francesca Mariana shows off a mouse skeleton that has been dyed to show bones and cartilage at the Stem Cell Day of Discovery event held at the USC Health Sciences Campus in Los Angeles, CA. February 4th, 2017. The event encourages students to learn more about STEM opportunities, including stem cell study and biotech, and helps demystify the fields and encourage student engagement. Photo by David Sprague

Dr. Francesca Mariana shows off a mouse skeleton that has been dyed to show bones and cartilage. Photo by David Sprague

USC masters student Shantae Thornton shows students how cells are held in long term cold storage tanks at -195 celsius at the Stem Cell Day of Discovery event held at the USC Health Sciences Campus in Los Angeles, CA. February 4th, 2017. The event encourages students to learn more about STEM opportunities, including stem cell study and biotech, and helps demystify the fields and encourage student engagement. Photo by David Sprague

USC masters student Shantae Thornton shows students how cells are held in long term cold storage tanks at -195 celsius. Photo by David Sprague

Genesis Archila, left, and Jasmine Archila get their picture taken at the Stem Cell Day of Discovery event held at the USC Health Sciences Campus in Los Angeles, CA. February 4th, 2017. The event encourages students to learn more about STEM opportunities, including stem cell study and biotech, and helps demystify the fields and encourage student engagement. Photo by David Sprague

Genesis Archila, left, and Jasmine Archila get their picture taken at the USC Stem Cell Day of Discovery. Photo by David Sprague

New stem cell recipes for making muscle: new inroads to study muscular dystrophy (Todd Dubnicoff)

Embryonic stem cells are amazing because scientists can change or specialize them into virtually any cell type. But it’s a lot easier said than done. Researchers essentially need to mimic the process of embryo development in a petri dish by adding the right combination of factors to the stem cells in just the right order at just the right time to obtain a desired type of cell.

Making human muscle tissue from embryonic stem cells has proven to be a challenge. The development of muscle, as well as cartilage and bone, are well characterized and known to form from an embryonic structure called a somite. Researches have even been successful working out the conditions for making somites from animal stem cells. But those recipes didn’t work well with human stem cells.

Now, a team of researchers at the Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research at UCLA has overcome this roadblock by carrying out a systematic approach using human tissue. As described in Cell Reports, the scientists isolated somites from early human embryos and studied their gene activity. By comparing somites that were just beginning to emerge with fully formed somites, the researchers pinpointed differences in gene activity patterns. With this data in hand, the team added factors to the cells that were known to affect the activity of those genes. Through some trial and error, they produced a recipe – different than those used in animal cells – that could convert 90 percent of the human stem cells into somites in only four days. Those somites could then readily transform into muscle or bone or cartilage.

This new method for making human muscle will be critical for the lab’s goal to develop therapies for Duchenne muscular dystrophy, an incurable muscle wasting disease that strikes young boys and is usually fatal by their 20’s.

The new protocol turned 90 percent of human pluripotent stem cells into somite cells in just four days; those somite cells then generated (left to right) cartilage, bone and muscle cells. Image: April Pyle Lab/UCLA

The new protocol turned 90 percent of human pluripotent stem cells into somite cells in just four days; those somite cells then generated (left to right) cartilage, bone and muscle cells. Image: April Pyle Lab/UCLA

Young man with spinal cord injury regains use of hands and arms after stem cell therapy

/ Kevin McCormack / 26 Comments

kris-boesen

Kris Boesen – Photo courtesy USC

Hope is such a fragile thing. We cling to it in bad times. It offers us a sense that we can bear whatever hardships we are facing today, and that tomorrow will be better.

Kris Boesen knows all about holding on to hope during bad times. On March 6th of this year he was left paralyzed from the neck down after a car accident. Kris and his parents were warned the damage might be permanent.

Kris says at that point, life was pretty bleak:

“I couldn’t drink, couldn’t feed myself, couldn’t text or pretty much do anything, I was basically just existing. I wasn’t living my life, I was existing.”

For Kris and his family hope came in the form of a stem cell clinical trial, run by Asterias Biotherapeutics and funded by CIRM. The Asterias team had already enrolled three patients in the trial, each of whom had 2 million cells transplanted into their necks, primarily to test for safety. In early April Kris became the first patient in the trial to get a transplant of 10 million stem cells.

Within two weeks he began to show signs of improvement, regaining movement and strength in his arms and hands:

“Now I have grip strength and do things like open a bottle of soda and feed myself. Whereas before I was relying on my parents, now after the stem cell therapy I am able to live my life.”

The therapy involves human embryonic stem cells that have been differentiated, or converted, into cells called oligodendrocyte progenitors. These are capable of becoming the kind of cells which help protect nerve cells in the central nervous system, the area damaged in spinal cord injury.

The surgery was performed by Keck Medicine of USC’s Dr. Charles Liu. In a news release about the procedure, he says improvements of the kind Kris has experienced can make a huge difference in someone’s life:

dr-liu

Dr. Charles Liu, Keck School of Medicine: Photo courtesy USC

“As of 90 days post-treatment, Kris has gained significant improvement in his motor function, up to two spinal cord levels. In Kris’ case, two spinal cord levels means the difference between using your hands to brush your teeth, operate a computer or do other things you wouldn’t otherwise be able to do, so having this level of functional independence cannot be overstated.”

We blogged about this work as recently as last week, when Asterias announced that the trial had passed two important safety hurdles.  But Kris’ story is the first to suggest this treatment might actually be working.

Randy Mills, CIRM’s President & CEO, says:

 “With each patient treated in this clinical trial we learn.  We gain more experience, all of which helps us put into better context the significance of this type of event for all people afflicted with debilitating spinal cord injuries. But let us not lose sight of the individual here.  While each participant in a clinical trial is part of the group, for them success is binary.  They either improve or they do not.  Kris bravely and selflessly volunteered for this clinical trial so that others may benefit from what we learn.  So it is fitting that today we celebrate Kris’ improvements and stop to thank all those participating in clinical trials for their selfless efforts.”

For patient advocates like Roman Reed, this was a moment to celebrate. Roman has been championing stem cell research for years and through his Roman Reed Foundation helped lay the groundwork for the research that led to this clinical trial:

“This is clear affirmative affirmation that we are making Medical History!  We were able to give a paralyzed quadriplegic patient back the use of his hands! With only half a clinical dosage. Now this person may hold and grasp his loved ones hands in his own hands because of the actions of our last two decades for medical research for paralysis CURE! CARPE DIEM!”

It’s not unheard of for people with the kind of injury Kris had to make a partial recovery, to regain some use of their arms and hands, so it’s impossible to know right now if the stem cell transplant was the deciding factor.

kris-2

Kris at home: photo courtesy USC

Kris’ dad, Rodney, says he doesn’t care how it happened, he’s just delighted it did:

“He’s going to have a life, even if (the progress) stops just this second, and this is what he has, he’s going to have a better life than he would have definitely had before, because there are so many things that this opens up the world for him, he’s going to be able to use his hands.”

Related Articles:

Scientists find new stem cell target for regenerating aging muscles

/ Karen Ring / Leave a comment

Young Arnold (wiki)

Young Arnold (wiki)

Today I’m going to use our former governor Arnold Schwarzenegger as an example of what happens to our muscles when we age.

One of Arnold’s many talents when he was younger was being a professional bodybuilder. As you can see in this photo, Arnold worked hard to generate an impressive amount of muscle that landed him lead roles in movies Conan the Barbarian and The Terminator.

Older Arnold

Older Arnold

If you look at pictures of Arnold now (who is now 68), while still being an impressively large human being, it’s obvious that much of his muscular bulk has diminished. That’s because as humans age, so do their muscles.

Muscles shrink with age

As muscles age, they slowly lose mass and shrink (a condition called sarcopenia) because of a number of reasons – one of them being their inability to regenerate new muscle tissue efficiently. The adult stem cells responsible for muscle regeneration are called satellite cells. When muscles are injured, satellite cells are activated to divide and generate new muscle fibers that can repair injury and also improve muscle function.

However, satellite cells become less efficient at doing their job over time because of environmental and internal reasons, and scientists are looking for new targets that can restore and promote the regenerative abilities of muscle stem cells for human therapeutic applications.

A study published earlier this week in Nature Medicine, identified a potential new target that could boost muscle stem cell regeneration and improved muscle function in a mouse model of Duchenne muscular dystrophy.

β1-integrin is important for muscle regeneration

Scientists from the Carnegie Institute of Washington found that β1-integrin is important for maintaining the homeostasis (or balance) of the muscle stem cell environment. If β1-integrin is doing its job properly, muscle stem cells are able to go about their regular routine of being dormant, activating in response to injury, dividing to create new muscle tissue, and then going back to sleep.

When the scientists studied the function of β1-integrin in the muscles of aged mice, they found that the integrin wasn’t functioning properly. Without β1-integrin, mouse satellite cells spontaneously turned into muscle tissue and were unable to maintain their regenerative capacity following muscle injury.

Upon further inspection, they found that β1-integrin interacts with a growth factor called fibroblast growth factor 2 (Fgf2) and this relationship was essential for promoting muscle regeneration following injury. When β1-integrin function deteriorates as in the muscles of aged mice, the mice lose sensitivity to the regenerative capacity of Fgf2.

Restoring muscle function in mice with muscular dystrophy

By using an antibody to artificially activate β1-integrin function in the muscles of aged mice, they were able to restore Fgf2 responsiveness and boosted muscle regeneration after injury. When a similar technique was used in mice with Duchenne muscular dystrophy, they observed muscle regeneration and improved muscle function.

Muscle loss seen in muscular dystrophy mice (left). Treatment with beta1 intern boosts muscle regeneration in the same mice (right). (Nature Medicine)

Muscle loss seen in muscular dystrophy mice (left). Treatment with B1-integrin boosts muscle regeneration in the same mice (right). (Nature Medicine)

The authors believe that β1-integrin acts as a sensor of the muscle stem cell environment that it maintains a balance between a dormant and a regenerative stem cell state. They conclude in their publication:

“β1-integrin senses the SC [satellite cell] niche to maintain responsiveness to Fgf2, and this integrin represents a potential therapeutic target for pathological conditions of the muscle in which the stem cell niche is compromised.”

Co-author on the study Dr. Chen-Ming Fan also spoke to the clinical relevance of their findings in a piece by GenBio:

“Inefficient muscular healing in the elderly is a significant clinical problem and therapeutic approaches are much needed, especially given the aging population. Finding a way to target muscle stem cells could greatly improve muscle renewal in older individuals.”

Does this mean anyone can be a body builder?

So does this study mean that one day we can prevent muscle loss in the elderly and all be body builders like Arnold? I highly doubt that. It’s important to remember these are preclinical studies done in mouse models and much work needs to be done to test whether β1-integrin is an appropriate therapeutic target in humans.

However, I do think this study sheds new light on the inner workings of the muscle stem cell environment. Finding out more clues about how to promote the health and regenerative function of this environment will bring the field closer to generating new treatments for patients suffering from muscle wasting diseases like muscular dystrophy.

Stem cell stories that caught our eye: sexual identity of organs, upping the game of muscle stem cells, mini guts produce insulin

/ Don Gibbons / 1 Comment

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.

A new sexual identity crisis—in our organs. With the transition from Mr. to Ms. Jenner and other transsexual news this year, it seems inevitable that a research paper would come out suggesting we may all have some mosaic sexual identity. A team in the U.K. found that the stem cells that develop our organs can have varying sexual identities and that can impact the function of the organ.

The organ in question in this case, intestines in fruit flies, is smaller in males than in females. By turning on and off certain genes the researchers at the Medical Research Council’s Clinical Science Centre found that making stem cells in the gut more masculine reduced their ability to multiply and produced smaller intestines. They also found that female intestines were more prone to tumors, just as many diseases are more common in one sex than the other.

In an interview with Medical News Today, Bruno Hudry, the first author on the paper, which is published in Nature, talked about the likelihood that we all have some adult cells in us with genes of the opposite sex.

 “This study shows that there is a wider spectrum than just two sexes. You can be chromosomally, hormonally or phenotypically female but still having some specific adult stem cells (here the stem cells of the intestine) acting like male. So it is hard to say if someone is “really” male or female. Some people are simply a mosaic of male and female cells within a phenotypically ‘male’ or ‘female’ body.”

Hurdry speculated that if the results are duplicated in humans it could provide a window into other sex-linked differences in diseases and could be a matching factor added to the standard protocol for blood and organ donations.

 

Reprogramming stomach to produce insulin.  The stem cells in our gut show an efficiency not seen in most of our organs. They produce a new lining for our stomach and intestine every few days. On the opposite end of the spectrum, the insulin-producing cells in our pancreas rank poorly in self renewal. So, what if you could get some of those vigorous gut stem cells to make insulin producing beta cells? Turns out you can and they can produce enough insulin to allow a diabetic mouse to survive.

mini stomach

A mini-gut with insulin-producing cells (red) and stem cells (green).

A team at the Harvard Stem Cell Institute manipulated three genes known to be associated with beta cell development and tested the ability of many different tissues—from tail to snout—to produce beta cells. A portion of the stomach near the intestine, which naturally produces other hormones, easily reprogrammed into insulin producing cells. More important, if the first batch of those cells was destroyed by the team, the remaining stem cells in the tissue quickly regenerated more beta cells. Since a misbehaving immune system causes type 1 diabetes, this renewal ability could be key to preventing a return of the disease after a transplant of these cells.

In the lab the researchers pushed the tissue from the pylorous region of the stomach to self-organize into mini-stomachs along with the three genetic factors that drive beta cell production.  When transplanted under the skin of mice that had previously had their beta cells destroyed, the mice survived. The genetic manipulations used in this research could not be used in people, but the team is working on a system that could.

 “What is potentially really great about this approach is that one can biopsy from an individual person, grow the cells in vitro and reprogram them to beta cells, and then transplant them to create a patient-specific therapy,” said Qiao Zhou, the senior author. “That’s what we’re working on now. We’re very excited.”

Medicalxpress ran a story about the work published in Cell Stem Cell.

 

muscle stem cells

Muscle stem cells generate new muscle (green) in a mouse.

Better way to build muscle.  Stem cells behave differently depending on what environment they find themselves in, but they are not passive about their environment. They can actively change it. A CIRM-funded team at Sanford Burnham Prebys Medical Discovery Institute (SBP) found that fetal muscle stem cells and adult muscle stem cells make very different changes in the micro-environment around them.

Fetal muscle stem cells become very good at generating large quantities of new muscle, while the adult stem cells take the role of maintaining themselves for emergencies. As a result, when major repair is needed like in muscular dystrophies and aging, they easily get overwhelmed. So the SBP team looked for ways to make the adult stem cells behave more like their fetal predecessors.

 “We found that fetal MuSCs remodel their microenvironment by secreting specific proteins, and then examined whether that same microenvironment can encourage adult MuSCs to more efficiently generate new muscle. It does, which means that how adult MuSCs normally support muscle growth is not an intrinsic characteristic, but can be changed,” said Matthew Tierney, first author of the study in an institute press release distributed by Newswise.

The results point to paths for developing therapies for a number of muscle wasting conditions.

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

/ cirmweb / Leave a comment

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.