Faulty fat stem cells & obesity-related diabetes

You see it in the news all the time: more and more people around the world are obese and as a result they’re at a higher risk for diabetes, heart disease and cancer. In fact, 90% of individuals with type 2 diabetes are overweight or obese.

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Fat cells (Image: Wikimedia Commons)

“Healthy” obese individuals protected from diabetes and other complications
A fascinating observation is that despite this tight association between weight and diabetes, some obese people are somehow shielded from the increased risks for diabetes and other associated diseases. Considering these conditions are among the leading causes of preventable death in the U.S., understanding how exactly these “healthy” obese individuals are protected could benefit millions of people.

A new study by researchers at the University of Bristol and Anti-Doping Laboratory Qatar (ADLQ) suggests that fat stem cells may hold the key to unlocking this mystery. Reporting in Diabetologia, the team found that fat stem cells from “healthy” obese people were better at storing fat compared to these same cells in people with increased risk for diabetes.

Belly fat and the development of diabetes
To delve deeper into the study, let’s take a closer look at the cellular biology of obesity and diabetes. The accumulation of fat in obese individuals initially leads to bigger fat cells but eventually causes the recruitment of fat stem cells. These additional fat cells can deposit as so-called visceral fat (aka belly fat) which accumulates within larger organs like the liver, heart and muscle instead of under the skin. Now, when a carbohydrate meal is eaten, the food is broken down into simple sugars which enter the blood. This rise in blood sugar is temporary because our organs like the liver and muscle use the sugar for energy. The blood sugar enters muscle and liver cells with the help of the hormone, insulin. But visceral fat mucks up these organs’ ability to sense insulin – they’re called insulin resistant – and blood sugar levels stay elevated which is the hallmark of type 2 diabetes (in type 1 diabetes the body doesn’t make any insulin).

In the study, the research team collected blood samples and isolated fat stem cells from 57 severely obese individuals undergoing liposuction.  Some of the volunteers were insulin resistant (their organs had a hard time taking up blood sugar despite the presence of insulin) and had obesity-related conditions like diabetes, hypertension and heart disease. The others were insulin sensitive (their organs could take in blood sugar) and had no signs of obesity-related conditions.

Obesity-related complications and faulty fat stem cells
It turned out that the fat stem cells from obese individuals with insulin resistance (increased risk of complications) did not store fat as well as the fat stem cells from the “healthy” obese subjects. It’s this inefficient fat storage that likely leads to the build-up of visceral fat.

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So why the difference? A comparison of various proteins in the blood of the two groups, showed that IL-6 – a protein secreted by the white blood cells of our immune system – was higher in the insulin resistant subjects. Back in the lab, the team found that the elevated IL-6 played a role in the cells’ reduced ability to store fat. Mohamed Elrayess, one of the authors from ADLQ, summarized the results in a press release:

“In this study we have shown that the impaired ability of fat stem cells to store excess fat was partially due to increased levels of the inflammatory marker interleukin-6 in the blood. Indeed, when fat stem cells isolated from healthy obese individuals were exposed to interleukin-6 in the laboratory, they behaved like those obtained from individuals with risk of diabetes.”

With this new piece of the obesity puzzle, the researchers are now focused on how they can make the fat stem cells from at risk individuals better at storing fat as a means to prevent the onset of diabetes.

Beige isn’t bland when it comes to solving the obesity epidemic

Americans spend over $60 billion a year to lose weight and yet two-thirds (that’s more than 200 million) are considered overweight or obese. Losing weight should be easy: just eat less and exercise more, right? But our body’s metabolism is a very complex thing and appears to fight against our best efforts to shed pounds. A recent analysis of clinical trial data and mathematical modeling suggests that over the long haul, none of the various diet strategies lead to meaningful weight loss. Even the contribution of exercise to weight loss has been called into question.

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Lose weight by simply eating less calories than you burn. Easier said than done! (Image credit)

All is not lost. In fact, the fat we carry in our bodies may hold the key to overcoming our obesity woes. A recent CIRM-funded UC Francisco study published in Cell Metabolism finds that harnessing a calorie burning form of fat cells may help guard against the development of obesity.

The Many Hues of Fat
Humans, like other mammals, have two very different types of fat tissue. The more abundant white fat acts to store fat and provides a form of energy to help our body function. An excess of white fat tissue is associated with metabolic diseases including diabetes and obesity. Brown fat tissue, on the other hand, generates heat and is associated with slimness. It was thought that only babies have brown fat which protects them against cold temperatures – they lack the muscle strength for the shivering response – but research in 2009 identified this fat tissue in adults as well.

The UCSF team, led by professor Shingo Kajimura, showed last year that adults actually have so-called beige fat cells that are able to switch from white to brown fat in the presence of colder temperatures and vice versa. This discovery presents the tantalizing potential of promoting weight loss in people by pushing white fat cells toward energy burning brown fat. In that earlier work, the team identified a protein that when inhibited with drugs caused the white fat cells to burn energy like the beige and brown fat. But this effect was short lived and these cells reverted back to the typical features of white fat cells. Kajimura reflected on these previous studies in a university press release:

“Our focus has been on learning to convert white fat into beige fat. Now we’re realizing we also have to think about how to keep it there for longer time.”

In the new study, the team focused on the fact that as beige cells revert back to white cells, their mitochondria – a cell’s energy producing factories – begin to disappear. First author Svetlana Altshuler-Keylin wanted to understand why:

“We knew that the color of brown and beige fat comes from the amount of pigmented mitochondria they contain, so we wondered whether something was going on with the mitochondria when beige fat turns white.”

Stopping cells from eating up too much mitochondria
Examining gene activity as cells went from beige to white implicated a process called autophagy was at play. This house cleaning function of a cell involves the breakdown of its own internal structures that are not functioning properly or aren’t needed. So perhaps stopping the autophagy process from occurring would prevent the energy burning beige cells from eating up their own mitochondria and reverting them back to the energy hoarding white cells.

To test this idea, the team relied on mice lacking genes that play important roles in autophagy. They beefed up their beige fat by subjecting the mice to cold temperatures. But when returned to a normal environment, the mice kept their beige fat and it didn’t convert back to white cells. This change impacted the mice overall health: when place on a fatty diet for two months these mice with the defective autophagy gained less weight. These mice were also able to better regulate blood sugar levels, an indication they there were protected from type 2 diabetes symptoms.

While these results represent very early stage research, Kajimura and his team now have a solid path to travel toward trying to help obese individual burn more calories, especially as they age:

“With age you tend to naturally lose your beige fat, which we think is one of the main drivers of age-related obesity. Your calorie intake stays the same, but you’re not burning as much. Maybe by understanding this process we can help people keep more beige fat, and therefore stay healthier.”

CIRM Board targets diabetes and kidney disease with big stem cell research awards

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A recent study  estimated there may be more than 500 million people worldwide who have diabetes. That’s an astounding figure and makes diabetes one of the largest chronic disease epidemics in human history.

One of the most serious consequences of untreated or uncontrolled diabetes is kidney damage. That can lead to fatigue, weakness, confusion, kidney failure and even death. So two decisions taken by the CIRM Board today were good news for anyone already suffering from either diabetes or kidney disease. Or both.

The Board awarded almost $10 million to Humacyte to run a Phase 3 clinical trial of an artificial vein needed by people undergoing hemodialysis – that’s the most common form of dialysis for people with kidney damage. Hemodialysis helps clean out impurities and toxins from the blood. Without it waste will build up in the kidneys with devastating consequences.

The artificial vein is a kind of bioengineered blood vessel. It is implanted in the individual’s arm and, during dialysis, is connected to a machine to move the blood out of the body, through a filter, and then back into the body. The current synthetic version of the vein is effective but is prone to clotting and infections, and has to be removed regularly. All this puts the patient at risk.

Humacyte’s version – called a human acellular vessel or HAV – uses human cells from donated aortas that are then seeded onto a biodegradable scaffold and grown in the lab to form the artificial vein. When fully developed the structure is then “washed” to remove all the cellular tissue, leaving just a collagen tube. That is then implanted in the patient, and their own stem cells grow onto it, essentially turning it into their own tissue.

In earlier studies Humacyte’s HAV was shown to be safer and last longer than current versions. As our President and CEO, Randy Mills, said in a news release, that’s clearly good news for patients:

“This approach has the potential to dramatically improve our ability to care for people with kidney disease. Being able to reduce infections and clotting, and increase the quality of care the hemodialysis patients get could have a significant impact on not just the quality of their life but also the length of it.”

There are currently almost half a million Americans with kidney disease who are on dialysis. Having something that makes life easier, and hopefully safer, for them is a big plus.

The Humacyte trial is looking to enroll around 350 patients at three sites in California; Sacramento, Long Beach and Irvine.

While not all people with diabetes are on dialysis, they all need help maintaining healthy blood sugar levels, particularly people with type 1 diabetes. That’s where the $3.9 million awarded to ViaCyte comes in.

We’re already funding a clinical trial with ViaCyte  using an implantable delivery system containing stem cell-derived cells that is designed to measure blood flow, detect when blood sugar is low, then secrete insulin to restore it to a healthy level.

This new program uses a similar device, called a PEC-Direct. Unlike the current clinical trial version, the PEC-Direct allows the patient’s blood vessels to directly connect, or vasularize, with the cells inside it. ViaCyte believes this will allow for a more robust engraftment of the stem cell-derived cells inside it and that those cells will be better able to produce the insulin the body needs.

Because it allows direct vascularization it means that people who get the delivery system  will also need to get chronic immune suppression to stop their body’s immune system attacking it. For that reason it will be used to treat patients with type 1 diabetes that are at high risk for acute complications such as severe hypoglycemic (low blood sugar) events associated with hypoglycemia unawareness syndrome.

In a news release Paul Laikind, Ph.D., President and CEO of ViaCyte, said this approach could help patients most at risk.

“This high-risk patient population is the same population that would be eligible for cadaver islet transplants, a procedure that can be highly effective but suffers from a severe lack of donor material. We believe PEC-Direct could overcome the limitations of islet transplant by providing an unlimited supply of cells, manufactured under cGMP conditions, and a safer, more optimal route of administration.”

The Board also approved more than $13.6 million in awards under our Discovery program. You can see the winners here.

 

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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Diabetes’ demise? Master Switch Identified for Turning Stem Cells into Functional Insulin-Producing Cells

It’s been a good week for diabetes researchers and the over one million Americans with type 1 diabetes who are hoping for an eventual stem cell-based treatment for this incurable disease. Published a day apart, two studies reported on achieving an elusive goal for the field: creating functional insulin-producing cells in a lab dish from induced pluripotent stem cells (iPS).

My fellow Stem Cellar blogger, Karen Ring, detailed one of the studies on Tuesday which used cells from human fat tissue (aka “love handles”) to devise a novel, consistent and efficient method for generating iPS-derived insulin-producing cells.

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Salk scientists identified a master switch, ERR-gamma, for making functional beta cells from stem cells. Image: Salk Institute

The other study is a CIRM-funded project by Salk Institute scientists. Reporting in Cell Metabolism, the team compared fetal and adult insulin-producing cells in mice and uncovered a protein “switch” that stimulates human iPS cells to fully mature into insulin-producing cells in a petri dish.

Because a very specific cell type is affected, the pancreatic beta cells, developing a cell therapy for diabetes would seem pretty straight-forward. Simply transplant stem cell-derived pancreatic beta-like cells that naturally release insulin in response to glucose. But over the years, researchers found that it wasn’t so easy to make fully mature stem cell-derived beta-like cells in the lab. The cells often got stuck at an immature stage of development resembling those found in the developing fetus.

The Case of the Missing Regulator of Insulin-Producing Cells
To get past this bottleneck the Salk team studied fetal and adult beta cells in mice in hopes that a comparison would reveal key missing ingredients for making fully functional beta-like cells. In particular, they compared the levels of transcription factors, proteins that turn genes on and off and are known to play important roles in determining the cell fate of stem cells. This analysis identified a transcription factor called ERR-gamma present in higher levels in adult cells compared to the fetal cells.

If this transcription factor is really important then removing it should have a very noticeable impact on maintaining blood glucose level. To test this idea, the team genetically engineered mice that lacked ERR-gamma. Sure enough, they showed that the beta cells of these mice did not release insulin in response to a large injection of glucose.

ERR-gamma: Master Switch for Making iβeta cells
Rather than knocking out ERR-gamma production, the researchers next manipulated human iPS cells to over produce ERR-gamma. When they attempted to mature those cells into beta-like cells, the ERR-gamma worked like a charm and helped generate cells that secrete insulin when glucose was added to the petri dish. To really nail down this result, the team repeated this lab experiment in animals. They transplanted these human iPS-derived beta-like cells, which they dubbed iβeta cells, into diabetic mice. Within days of the transplantation, the mice had normal blood sugar levels.

This compelling result points to ERR-gamma as a master regulator of beta cell development and a possible answer to readily making a cell therapy product. As Evans mentions in a press release, he’s cautiously optimistic about the future:

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Study authors (from left): Michael Downes, Ron Evans and Eiji Yoshihara

“Hopefully, this mirrors what would happen in the clinic—after someone is diagnosed with diabetes they could potentially get this treatment. It’s exciting because it suggests that cells in a dish are ready to go.”

For Your Consideration

And because the cells are derived from human iPS cells, each patient could potentially have beta cells tailor made from their own skin or blood sample. The advantage here is that the transplant is less likely to be rejected by the immune system. But type 1 diabetes is an autoimmune disease in which the immune system attacks the beta cells as if they were foreign to the body. So it’s possible that those transplanted cells would still be vulnerable if the autoimmune environment is still present.

A CIRM-funded clinical trial, sponsored by ViaCyte, Inc., is currently testing an embryonic stem cell-based therapy for type 1 diabetics and gets around this immune system problem by shielding the cell product inside an encapsulation device which is placed under the skin. Also, the ViaCyte product does not use fully mature beta-like cells but instead transplants earlier stage progenitor cells and lets them develop into functioning beta cells inside the patient.

Many Shots on Goal – It’s a Good Thing
Which methods will work? Are “love handle” beta cells better than ERR-gamma ones? Oh, and what about the report in January that reprogrammed skin cells directly into functional beta cells? Is that the way to go? And will the ViaCyte progenitor cells successfully develop and function inside people with diabetes?  Ultimately, only clinical testing will be able to answer these questions. It’s exciting to see so many research teams making progress toward cell therapies for diabetes. As we often say here, the more shots the field takes, the more likely someone will score the game-changing goal of curing diabetes.

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

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.

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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.

Protective cell therapy could mean insulin independence for diabetic patients

This has already been a productive year for diabetes research. Earlier this month, scientists from UCSF and the Gladstone Institutes successfully made functional human pancreatic beta cells from skin, providing a new and robust method for generating large quantities of cells to replace those lost in patients suffering from type 1 diabetes.

Today marks another breakthrough in the development of stem cell therapies for diabetes. Scientists from MIT and the Harvard Stem Cell Institute published a new method in Nature Medicine that encapsulates and protects stem cell-derived pancreatic beta cells in a way that prevents them from being attacked by the immune system after transplantation.

Protecting transplanted cells from the immune system

Stem cell therapy holds promise for diabetes for a number of reasons. First, scientists now have the ability to generate large numbers of insulin producing pancreatic beta cells from human skin and stem cells. This obviates the need for donor beta cells, which are always in short supply and high demand. Second, there’s the issue of the immune system. Transplanting beta cells from a donor into a patient will trigger an immunological reaction, which can only be abated by a lifetime regimen of immunosuppressive drugs.

One way that scientists have addressed the issue of immune rejection is to transplant stem cell-derived beta cells in a protected capsule. A CIRM-funded company called ViaCyte has developed a medical device that acts like a replacement pancreas but is surgically implanted under the skin. It contains human beta cells derived from embryonic stem cells and has a membrane barrier that allows only certain molecules to pass in and out of the device. This way, the foreign pancreatic cells are shielded from the immune system, but they can still respond to changing blood sugar levels in the patient by secreting insulin into the blood stream.

Another way that scientists trick the immune system in diabetes patients uses a similar strategy but instead of a medical device that protects a large population of cells, they encapsulate individual islets (clusters of beta cells) using biomaterials.

However, previous attempts using a biomaterial called alginate to encapsulate islets caused an immune response in the form of fibrosis, or scar tissue, and cell death. Additionally, transplanted alginate microspheres were only able to achieve glycemic control, or control of blood sugar levels, temporarily in animal models.

In the Nature Medicine study, the scientists developed a new method for beta cell encapsulation where they used a chemically modified version of the alginate microspheres – triazole-thiomorpholine dioxide (TMTD) – that didn’t cause an immune reaction and was able to maintain glycemic control in mice that had diabetes.

New protective method makes diabetic mice insulin independent

The scientists tested the conventional alginate microspheres and the modified TMTD-alginate microspheres containing embryonic stem cell-derived human beta islets in diabetic mice.

Encapsulated beta islets were transplanted into diabetic mice. (Nature Medicine)

Encapsulated beta islets were transplanted into diabetic mice. (Nature Medicine)

They found that the conventional smaller alginate microspheres caused fibrosis while larger TMTD-alginate microspheres did not. They observed that the modified TMTD-alginate microspheres were able to achieve glycemic control for over 70 days after transplantation while conventional microspheres didn’t perform as well.

The scientists also looked at the immune response to both types of alginate spheres. They saw lower numbers of immune cells and less fibrosis surrounding the transplanted TMTD microspheres compared to the conventional microspheres.

The final studies were the icing on the cake. The asked whether the modified TMTD microspheres were able to maintain long-term glycemic control or insulin independence, which would mean sustaining blood glucose levels in diabetic mice for over 100 days. They studied diabetic mice that received TMTD microspheres for 174 days. At 150 days, they performed a glucose test and saw that the diabetic mice were just as good at regulating glucose levels as normal mice. Furthermore, after 6 months, these mice showed no build up of fibrotic tissue, indicating that the modified microspheres weren’t causing an immune response and these mice didn’t need immunosuppressive drugs.

What the experts had to say…

This study was picked up by STATnews, which also mentioned another related study published in Nature Biotechnology that tested various alginate derivatives in rodent and monkey models of diabetes.

Julia Greenstein, vice president of discovery research at JDRF, discussed the implications of both studies with STATnews:

“This is really the first demonstration of the ability of these novel materials in combination with a stem-cell derived beta cell to reverse diabetes in an animal model. Our goal is to bring that kind of biological cure across the spectrum of type 1 diabetes.”

First author on both studies, Arturo Vegas, also gave his thoughts and discussed future applications:

Arturo Vegas

Arturo Vegas

“From very early on, we were getting great success. Everything kind of fell into place. You saw less foreign body response. The human beta cells survived exquisitely well. I think we’ve advanced the ball pretty far, almost as far you could get in an academic environment. The talk is shifting toward doing something clinically.”

According to STATnews, Vegas and his team are working on tests now in monkey models. “Vegas said that if the primate studies are successful, the next step will be developing a therapy to be used in people.”


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A Win for Diabetes: Scientists Make Functional Pancreatic Cells From Skin

Today is an exciting day for diabetes research and patients. For the first time, scientists have succeeded in making functional pancreatic beta cells from human skin. This new method for making the insulin-producing cells of the pancreas could produce a new, more effective treatment for patients suffering from diabetes.

Researchers at the Gladstone Institutes and the University of California, San Francisco published these promising findings today in the journal Nature Communications.

Making pancreatic cells from skin

They used a technique called direct reprogramming to turn human skin cells directly into pancreatic beta cells without having to go all the way back to a pluripotent stem cell state. The skin cells were treated with factors used to generate induced pluripotent stem cells (iPSCs) and with pancreatic-specific molecules. This cocktail of factors and molecules shut off the skin genes and turned on genes of the pancreas.

The end product was endoderm progenitor cells, which are like stem cells but can only generate cell types specific to organs derived from the endoderm layer (for example: lungs, thyroid, pancreas). The scientists took these endoderm progenitors and further coaxed them into mature, pancreatic beta cells after treatment with another cocktail of molecules.

Functioning human pancreatic cells after they’ve been transplanted into a mouse. (Image: Saiyong Zhu, Gladstone)

Functioning human pancreatic cells after they’ve been transplanted into a mouse. (Image: Saiyong Zhu, Gladstone)

While the pancreatic cells they made looked and acted like the real thing in a dish (they were able to secrete insulin when exposed to glucose), the authors needed to confirm that they functioned properly in animals. They transplanted the mature beta cells into mice that were engineered to have diabetes, and observed that the human beta cells protected the mice from becoming diabetic by properly regulating their blood glucose levels.

Importantly, none of the mice receiving human cells got tumors, which is always a concern when transplanting reprogrammed cells or cells derived from pluripotent stem cells.

What does this mean?

This study is groundbreaking because it offers a new and more efficient method to make functioning human beta cells in mass quantities.

Dr. Sheng Ding, a CIRM funded senior investigator at the Gladstone and co-senior author, explained in a Gladstone news release:

Sheng Ding

Sheng Ding

“This new cellular reprogramming and expansion paradigm is more sustainable and scalable than previous methods. Using this approach, cell production can be massively increased while maintaining quality control at multiple steps. This development ensures much greater regulation in the manufacturing process of new cells. Now we can generate virtually unlimited numbers of patient-matched insulin-producing pancreatic cells.”

 

Matthias Hebrok, director of the Diabetes Center at UCSF and co-senior author on paper discussed the potential research and clinical applications of their findings:

Mattias Hebrok

Matthias Hebrok

“Our results demonstrate for the first time that human adult skin cells can be used to efficiently and rapidly generate functional pancreatic cells that behave similar to human beta cells. This finding opens up the opportunity for the analysis of patient-specific pancreatic beta cell properties and the optimization of cell therapy approaches.”

 

The study does mention the caveat that their direct reprogramming approach wasn’t able to generate all the cell types of the pancreas. Having these support cells would better recreate the pancreatic environment and likely improve the function of the transplanted beta cells.

Lastly, I find this study exciting because it kills two birds with one stone. Scientists can use this technique to make better cellular models of diabetes to understand why the disease happens, and they could also develop new cell replacement therapies in humans. Already, stem cell derived pancreatic beta cells are being tested in human clinical trials for type 1 diabetes (one of them is a CIRM-funded clinical trial by Viacyte) and it seems likely that beta cells derived from skin will follow suit.


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Type 1 Diabetes Trial Explained Whiteboard Video Style

There’s a saying, a picture is worth a thousand words. With complicated science however, pictures don’t always do these topics justice. Here’s where videos come to the rescue.

Florie Mar, founder of Youreka Science.

Florie Mar, founder of Youreka Science.

Today’s topic is type 1 diabetes and a CIRM-funded clinical trial headed by the San Diego company ViaCyte hoping to develop a cure for patients with this disease. Instead of writing an entire blog about the latest on this clinical trial, we are featuring an excellent video by Youreka Science. This nonprofit organization is the brainchild of former University of California, San Francisco graduate student Florie Mar who has a passion to bring scientific concepts to life to reach both students and the general public.

Youreka’s style uses whiteboard videos to explain disease and basic science research with drawings, words, and lay person-friendly narrative. This particular video, “Progress and Promise of Stem Cell Research: Type 1 Diabetes” was developed in collaboration with Americans for Cures and explains how CIRM-funded stem cell research is “leading to groundbreaking advances in diabetes.”

We are also excited about this ViaCyte trial as it’s being conducted in one of the CIRM Alpha Stem Cell Clinics located at the University of California, San Diego. The goal of the Alpha Clinics is to accelerate the development and delivery of stem cell therapies to patients by providing stem-cell focused clinics for conducting high quality trials.

In brief, the video explains ViaCyte’s stem cell derived therapy that replaces the insulin-producing cells that are lost in type 1 diabetes patients. For more details, check out the video!

 

And to hear from Viacyte’s chief scientific officer as well as two people living with type 1 diabetes, check out a CIRM video we produced a few years ago.


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