Month: May 2017

Stem cell study shows how smoking attacks the developing liver in unborn babies

/ Kevin McCormack / Leave a comment

smoking mom

It’s no secret that smoking kills. According to the Centers for Disease Control and Prevention (CDC) smoking is responsible for around 480,000 deaths a year in the US, including more than 41,000 due to second hand smoke. Now a new study says that damage can begin in utero long before the child is born.

Previous studies had suggested that smoking could pose a serious risk to a fetus but those studies were done in petri dishes in the lab or using animals so the results were difficult to extrapolate to humans.

Researchers at the University of Edinburgh in Scotland got around that problem by using embryonic stem cells to explore how the chemicals in tobacco can affect the developing fetus. They used the embryonic stem cells to develop fetal liver tissue cells and then exposed those cells to a cocktail of chemicals known to be found in the developing fetus of mothers who smoke.

Dangerous cocktail

They found that this chemical cocktail proved far more potent, and damaged the liver far more, than individual chemicals. They also found it damaged the liver of males and females in different ways.  In males the chemicals caused scarring, in females it was more likely to negatively affect cell metabolism.

There are some 7,000 chemicals found in cigarette smoke including tar, carbon monoxide, hydrogen cyanide, ammonia, and radioactive compounds. Many of these are known to be harmful by themselves. This study highlights the even greater impact they have when combined.

Long term damage

The consequences of exposing a developing fetus to this toxic cocktail can be profound, including impaired growth, premature birth, hormonal imbalances, increased predisposition to metabolic syndrome, liver disease and even death.

The study is published in the Archives of Toxicology.

In a news release Dr. David Hay, one of the lead authors, said this result highlights yet again the dangers posed to the fetus by women smoking while pregnant or being exposed to secondhand smoke :

“Cigarette smoke is known to have damaging effects on the foetus, yet we lack appropriate tools to study this in a very detailed way. This new approach means that we now have sources of renewable tissue that will enable us to understand the cellular effect of cigarettes on the unborn foetus.”

“A limitless future”: young crash victim regains hand, finger movement after CIRM-funded trial

/ Todd Dubnicoff / 3 Comments

Back in March, we reported on Asterias Biotherapeutics’ exciting press release stating that its CIRM-funded stem cell-based therapy for spinal cord injury had shown improvement in six out of the six clinical trial patients receiving a ten million cell dose. What’s even more exciting is hearing stories about the positive impact of that data on specific people’s lives. People like Lucas Lindner of Eden, Wisconsin.

Lucas Lindner was left paralyzed below the chin after a truck accident last May. Photo: Fox6Now, Milwaukee

Just over a year ago, Lucas headed out in his truck on a Sunday morning to pick up some doughnuts for his grandmother. Along the way, he suddenly saw a deer in the road and, in swerving to avoid hitting the animal, Lucas’ truck flipped over. He was thrown through the window and suffered a severe spinal cord injury leaving him without the use of his arms and legs.

Linder was the 2nd person to receive a 10 million dose of Asterias’ CIRM-funded stem cell-based therapy for spinal cord injury. Video still: Fox6Now, Milwaukee

Earlier this month, Lucas was featured in a local Milwaukee TV news report that highlights his incredible recovery since participating in the Asterias trial shortly after his accident. Surgeons at Medical College of Wisconsin – one of the clinical trial sites – injected 10 million AST-OPC1 cells into the site of the spinal cord injury a few inches below his skull. The AST-OPC1 product contains oligodendrocyte progenitor cells, which when fully matured are thought to help restore nerve signaling in the frayed spinal cord nerve cells.

Lucas was just the second person nationally to receive the 10 million cell dose, and since that time, he’s regained movement in his arms, hands and fingers. This improvement may seem moderate to an outside observer, but for Lucas, it’s life changing because it gives him the independence to pursue his dreams of working in the IT and electronics fields:

“Now that I have near 100% full range on all of my fingers, that pretty much brings everything I ever wanted to do back. It lets you contribute to society. Words can’t express how amazing it feels…The future really is limitless,” he said during the TV new segment.

While regaining movement spontaneously without a stem cell treatment is not unheard of, the fact that all six of the trial participants receiving 10 million cells had improvements suggests the stem cell-based therapy is having a positive impact. We’re hopeful for further good news later this year when Asterias expects to provide more safety and efficacy data on participants given the 10 million cell dose as well as others who received the maximum 20 million cell dose.

Stem cell stories that caught our eye: new baldness treatments?, novel lung stem cells, and giraffe stem cells

/ Todd Dubnicoff / Leave a comment

Novel immune system/stem cell interaction may lead to better treatments for baldness. When one thinks of the immune system it’s usually in terms of the body’s ability to fight off a bad cold or flu virus. But a team of UCSF researchers this week report in Cell that a particular cell of the immune system is key to instructing stem cells to maintain hair growth. Their results suggest that the loss of these immune cells, called regulatory T cells (Tregs for short), may be the cause of baldness seen in alopecia areata, a common autoimmune disorder and may even play a role in male pattern baldness.

Alopecia, a common autoimmune disorder that causes baldness. Image: Shutterstock

While most cells of the immune system recognize and kill foreign or dysfunctional cells in our bodies, Tregs act to subdue those cells to avoid collateral damage to perfectly healthy cells. If Tregs become impaired, it can lead to autoimmune disorders in which the body attacks itself.

The UCSF team had previously shown that Tregs allow microorganisms that are beneficial to skin health in mice to avoid the grasp of the immune system. In follow up studies they intended to examine what happens to skin health when Treg cells were inhibited in the skin of the mice. The procedure required shaving away small patches of hair to allow observation of the skin. Over the course of the experiment, the scientists notice something very curious. Team lead Dr. Michael Rosenblum recalled what they saw in a UCSF press release:

“We quickly noticed that the shaved patches of hair never grew back, and we thought, ‘Hmm, now that’s interesting. We realized we had to delve into this further.”

That delving showed that Tregs are located next to hair follicle stem cells. And during the hair growth, the Tregs grow in number and surround the stem cells. Further examination, found that Tregs trigger the stem cells through direct cell to cell interactions. These mechanisms are different than those used for their immune system-inhibiting function.

With these new insights, Dr. Rosenblum hopes this new-found role for Tregs in hair growth may lead to better treatments for Alopecia, one of the most common forms of autoimmune disease.

Novel lung stem cells bring new insights into poorly understood chronic lung disease. Pulmonary fibrosis is a chronic lung disease that’s characterized by scarring and changes in the structure of tiny blood vessels, or microvessels, within lungs. This so-called “remodeling” of lung tissue hampers the transfer of oxygen from the lung to the blood leading to dangerous symptoms like shortness of breath. Unfortunately, the cause of most cases of pulmonary fibrosis is not understood.

This week, Vanderbilt University Medical Center researchers report in the Journal of Clinical Investigation the identification of a new type of lung stem cell that may play a role in lung remodeling.

Susan Majka and Christa Gaskill, and colleagues are studying certain lung stem cells that likely contribute to the pathobiology of chronic lung diseases.  Photo by: Susan Urmy

Up until now, the cells that make up the microvessels were thought to contribute to the detrimental changes to lung tissue in pulmonary fibrosis or other chronic lung diseases. But the Vanderbilt team wasn’t convinced since these microvessel cells were already fully matured and wouldn’t have the ability to carry out the lung remodeling functions.

They had previously isolated stem cells from both mouse and human lung tissue located near microvessels. In this study, they tracked these mesenchymal progenitor cells (MPCs) in normal and disease inducing scenarios. The team’s leader, Dr. Susan Majka, summarized the results of this part of the study in a press release:

“When these cells are abnormal, animals develop vasculopathy — a loss of structure in the microvessels and subsequently the lung. They lose the surfaces for gas exchange.”

The team went on to find differences in gene activity in MPCs from healthy versus diseased lungs. They hope to exploit these differences to identify molecules that would provide early warnings of the disease. Dr. Majka explains the importance of these “biomarkers”:

“With pulmonary vascular diseases, by the time a patient has symptoms, there’s already major damage to the microvasculature. Using new biomarkers to detect the disease before symptoms arise would allow for earlier treatment, which could be effective at decreasing progression or even reversing the disease process.”

The happy stem cell story of Mahali the giraffe. We leave you this week with a feel-good story about Mahali, a 14-year old giraffe at the Cheyenne Mountain Zoo in Colorado. Mahali had suffered from chronic arthritis in his front left leg. As a result, he could not move well and was kept isolated from his herd.

Giraffes at Cheyenne Mountain Zoo. Photo: Denver Post

The zoo’s head veterinarian, Dr. Liza Dadone, decided to try a stem cell therapy procedure to bring Mahali some relief and a better quality of life. It’s the first time such a treatment would be performed on a giraffe. With the help of doctors at Colorado State University’s James L. Voss Veterinary Teaching Hospital, 100 million stem cells grown from Mahali’s blood were injected into his arthritic leg.

Before treatment, thermograph shows inflammation (red/yellow) in Mahali’s left front foot (seen at far right of each image); after treatment inflammation resolved (blue/green). Photos: Cheyenne Mountain Zoo

In a written statement to the Colorado Gazette, Dr. Dadone summarized the positive outcome:

“Prior to the procedure, he was favoring his left front leg and would lift that foot off the ground almost once per minute. Since then, Mahali is no longer constantly lifting his left front leg off the ground and has resumed cooperating for hoof care. A few weeks ago, he returned to life with his herd, including yard access. On the thermogram, the marked inflammation up the leg has mostly resolved.”

Now, Dr. Dadone made sure to state that other treatments and medicine were given to Mahali in addition to the stem cell therapy. So, it’s not totally clear to what extent the stem cells contributed to Mahali’s recovery. Maybe future patients will receive stem cells alone to be sure. But for now, we’re just happy for Mahali’s new lease on life.

New target for defeating breast cancer stem cells uncovered

/ Todd Dubnicoff / 2 Comments

Stashed away in most of your tissues and organs lie small populations of adult stem cells. They help keep our bodies functioning properly by replenishing dying or damaged cells. Their ability to make more copies of themselves, as needed, ensures that there’s always an adequate supply set aside. But this very same self-renewing, life-sustaining property of adult stem cells is deadly in the hands of cancer stem cells. Also called tumor-initiating cells, cancer stem cells sustain tumor growth even after chemotherapy and are thought to be a primary cause of cancer relapse.

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Microscopic image of normal mouse mammary ducts. Mammary stem cells are found among basal cells (green). Image courtesy of Toni Celià-Terrassa and Yibin Kang, Princeton University

By studying adult and cancer stem cells side-by-side, Princeton researchers report this week in Nature Cell Biology that they’ve uncovered a common function in both cells types that not only helps explain an adult stem cell’s self-renewing ability but also points to new therapeutic approaches to targeting breast cancer stem cells.

Both adult and cancer stem cells continually resist signals from their environment that encourage them to specialize, or differentiate, into a particular cell type. Once specialized, the cells lose their ability to self-renew and will eventually die off. Now, if all the adult stem cells in an organ followed that instruction, they would eventually become depleted and the organ would lose the ability to repair itself. The same holds true for cancer stem cells which actually would be a good thing since it would lead to the tumor’s death.

The Princeton team first identified a molecule called miR-199a that allows mammary (breast) stem cells to resist differentiation signals by directly blocking the production of a protein called LCOR. Artificially boosting the amount of miR-199a led to a decrease in LCOR levels and an increase in stem cell function. But when LCOR levels were increased, mammary stem cell function was restricted.

The researchers then turned their attention to breast cancer stem cells and found the same miR-199a/LCOR function at work. In a similar fashion, boosting miR-199a levels enhanced cancer stem cell function and increased tumor formation while increasing LCOR restricted the tumor-forming ability of the breast cancer stem cells.

These lab results also matched up with tissue samples taken from breast cancer patients. High miR-199a levels in the samples correlated with low patient survival rates. But those with high levels of LCOR showed a better prognosis.

It turns out that cells in our immune system are responsible for boosting LCOR in mammary and breast cancer stem cells by releasing a protein called interferon alpha. So the presence of interferon alpha nudges mammary stem cells to mature into mammary gland cells and inhibits breast cancer stems from forming tumors. But in the presence of elevated miR-199a levels, mammary and breast cancer stem cells are protected and maintain their numbers by deactivating the interferon alpha/LCOR signal.

If you’re still with me, these results point to miR-199a as a promising target for restoring interferon-alpha’s cancer interfering properties. Team leader Dr. Yibin Kang highlighted this possibility in a Princeton University press release:

“Interferons have been widely used for the treatment of multiple cancer types. These treatments might become more effective if the interferon-resistant cancer stem cells can be rendered sensitive by targeting the miR-199a-LCOR pathway.”

ViaCyte Advances Cell Replacement Therapy for High Risk Type 1 Diabetes

/ Karen Ring / Leave a comment

San Diego regenerative medicine company ViaCyte announced this week that the Food and Drug Administration (FDA) approved their Investigational New Drug (IND) Application for PEC-Direct, a cell-based therapy to treat patients at risk for severe complications caused by type 1 diabetes. In the US, IND approval is the final regulatory step required before a therapy can be tested in clinical trials.

PEC-Direct is a combination therapy consisting of cells encapsulated in a device that aims to replace the insulin-producing islet cells of the pancreas destroyed in patients with type 1 diabetes. The device contains human stem cell-derived pancreatic progenitor cells that develop into insulin-secreting cells when the device is placed under the patient’s skin. Ports on the surface of the device allow blood vessels from the host to directly contact the cells within, allowing for engraftment of the transplanted cells and for their maturation into islet cells.  These cells can sense and regulate blood glucose levels by secreting the hormones found in islets, including insulin.

ViaCyte’s PEC-Direct device allows a patient’s blood vessels to integrate and make contact with the transplanted cells.

Because PEC-Direct allows for “direct vascularization”, in effect connecting the device to the blood system, patients will need to take immunosuppressive drugs to prevent rejection of the donor cells. ViaCyte is therefore testing this therapy in patients who are at risk for serious complications associated with type 1 diabetes like severe hypoglycemia where a patient’s blood sugar is so low they need immediate medical assistance.

Severe hypoglycemia can occur because people with diabetes must inject insulin to control elevated blood sugar, but the injections can exceed the patients’ needs. The resulting low blood sugar can lead to dizziness, irregular heartbeat, and unconsciousness, even death. In some cases, sufferers are not aware of their hypoglycemia symptoms, putting them at increased risk of these life-threatening complications.

ViaCyte’s President and CEO, Dr. Paul Laikind, explained in a news release,

Paul Laikind

“While insulin therapy transformed type 1 diabetes from a death sentence to a chronic illness, it is far from a cure. Type 1 diabetes patients continue to deal with the daily impact of the disease and remain at risk for often severe long-term complications.  This is especially true for the patients with high-risk type 1 diabetes, who face challenges such as hypoglycemia unawareness and life-threatening severe hypoglycemic episodes.  These patients have a particularly urgent unmet medical need and could benefit greatly from cell replacement therapy.”

Approximately 140,000 people in the US and Canada suffer from this form of high-risk diabetes. These patients qualify for islet transplants from donated cadaver tissue. But because donor islets are in limited supply, ViaCyte Clinical Advisor, Dr. James Shapiro at the University of Alberta, believes PEC-Direct will address this issue by providing an unlimited supply of cells.

“Islet transplants from scarce organ donors have offered great promise for those with unstable, high-risk type 1 diabetes, but the procedure has many limitations.  With an unlimited supply of new islets that the stem cell-derived therapy promises, we have real potential to benefit far more patients with islet cell replacement.”

The company’s preclinical research on PEC-Direct, leading up to the FDA’s IND approval, was funded by a CIRM late stage preclinical grant. ViaCyte now plans to launch a clinical trial this year that will evaluate the safety and efficacy of PEC-Direct in the US and Canada. They will enroll approximately 40 patients at multiple clinical trial centers including the University of Alberta in Edmonton, the University of Minnesota, and UC San Diego. The trial will test whether the device is safe and whether the transplanted cells can produce enough insulin to relieve patients of insulin injections and hypoglycemic events.

ViaCyte has another product called PEC-Encap, a different implantable device that contains the same cells but protects these cells from the patient’s immune system. The device is being tested in a CIRM-funded Phase 1/2a trial, and ViaCyte is currently collaborating with W. L. Gore & Associates to improve the design of PEC-Encap to improve consistency of engraftment in patients.

Advocating for Huntington’s Disease: Daniel Medina’s Journey

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Daniel Medina

In honor of Huntington’s Disease (HD) Awareness Month, we’re featuring a guest blog by HD patient advocate Daniel Medina. Daniel became actively involved in the HD community when he learned that his younger brother was at risk for inheriting this devastating neurodegenerative disease. Since then he has been a champion for HD awareness by organizing HD patient support groups and walks in southern California and serving on the Board of HD Care, UC Irvine’s non-profit HD support group. 

Guest Blog by Daniel Medina

A visit to a care home back in April of 2012 changed my life forever. It all started when my mother took my 14-year-old half-brother to meet his grandfather for the very first time. My brother’s aunt led the way to what seemed to be an emotional, long overdue family encounter.  As they walked into his room they were impacted by what they saw.

They saw an elderly, bedridden gentleman that suffered from uncontrollable body movements. He was unable to communicate and was totally dependent on others. As the tears flowed, so did my mom’s sense of urgency to find out the name of his affliction. That’s when the words “Huntington’s disease” were uttered by my brother’s aunt. Her knowledge was limited to sharing that it was a genetic disease.

I immediately began my own research as the details of this encounter were relayed to me. My curiosity soon turned into despair and anguish as I learned that my brother was at risk of being a carrier of this horrible neurodegenerative disease.  I felt empowered as I began attending HD fundraising events. There I met so many courageous families that clung to the hope of a better tomorrow.  This hope came through the possibility of scientists working towards finding a treatment or a cure through stem cell research.

As of 2013 my role had evolved from an event attendee to a patient advocate. It became clear to me that there was an immediate need to fill voids that were unattended. In 2014, I started an HD support group in my area in order to tend to the needs of the HD community. The appreciation and gratitude I felt made every second I invested very much worthwhile.

In the last three years, we have seen the tremendous impact and growth HD organizations like Help4HD International, HD CARE and WeHaveAFace, have had on a local and global scale. It has been such an honor and a privilege to work alongside them. Our collaborative efforts have had a ripple effect of amazing results. The success of one is the success of all.

At the beginning of 2015, I was introduced to Americans for Cures. Working to promote and educate the public about the benefits of stem cell stem research was a perfect fit. Meeting advocates from other disease communities has educated me and taught me how our common goals towards finding cures unites us.

My HD Advocacy journey began with a simple visit to a care home. In a matter of a few years, it has transformed into a life mission to help those suffering the effects of this terrible disease.

2016 HD-CARE Conference. Patient Advocates Ron Shapiro, Adrienne Shapiro, David Saldana, Frances Saldana, Daniel Medina with Karen Ring from CIRM.

Texas tries to go it alone in offering unproven stem cell therapies to patients

/ Kevin McCormack / 5 Comments

Texas Capitol. (Shutterstock)

One of the most hotly debated topics in stem cell research is whether patients should be able to have easier access to unproven therapies using their own stem cells, at their own risk, and their own cost. It’s a debate that is dividing patients and physicians, researchers and lawmakers.

In California, a bill working its way through the state legislature wants to have warning signs posted in clinics offering unproven stem cell therapies, letting patients know they are potentially putting themselves at risk.

Texas is taking a very different approach. A series of bills under consideration would make it easier for clinics to offer unproven treatments; make it easier for patients with chronic illnesses to use the “right to try” law to take part in early-stage clinical trials (in the past, it was only patients with a terminal illness who could do that); and allow these clinics to charge patients for these unproven stem cell therapies.

Not surprisingly, the Texas bills are attracting some widely divergent views. Many stem cell researchers and some patient advocates are opposed to them, saying they prey on the needs of vulnerable people, offering them treatments – often costing thousands, even tens of thousands of dollars – that have little or no chance of success.

In an article on STATnews, Sean Morrison, a stem cell researcher at the University of Texas Southwestern Medical Center, in Dallas, said the Texas bills would be bad for patients:

“When patients get desperate, they have a capacity to suspend disbelief. When offered the opportunity of a therapy they believe in, even without data and if the chances of benefit are low, they’ll fight for access to that therapy. The problem is there are fraudulent stem cell clinics that have sprung up to exploit that.”

Patients like Jennifer Ziegler disagree with that completely. Ziegler has multiple sclerosis and has undergone three separate stem cell treatments – two in the US and one in Panama – to help treat her condition. She is also a founding member of Patients For Stem Cells (PFSC):

Jennifer Ziegler

“PFSC does not believe our cells are drugs. We consider the lack of access to adult stem cells an overreach by the federal government into our medical freedoms. My cells are not mass produced, and they do not cross state lines. An adult stem cell treatment is a medical procedure, between me, a fully educated patient, and my fully competent doctor.”

The issue is further complicated because the US Food and Drug Administration (FDA) – which has regulatory authority over stem cell treatments – considers the kinds of therapies these clinics offer to be a technical violation of the law. So even if Texas passes these three bills, they could still be in violation of federal law. However, a recent study in Cell Stem Cell showed that there are some 570 clinics around the US offering these unproven therapies, and to date the FDA has shown little inclination to enforce the law and shut those clinics down.

UC Davis stem cell researcher – and CIRM grantee – Paul Knoepfler is one of the co-authors of the study detailing how many clinics there are in the US. On his blog – The Niche – he recently expressed grave concerns about the Texas bills:

Paul Knoepfler

“The Texas Legislature is considering three risky bills that would give free rein to stem cell clinics to profit big time off of patients by selling unproven and unapproved “stem cell treatments” that have little if any science behind them. I call one of these bills “Right to Profit” for clinics, which if these became law could get millions from vulnerable patients and potentially block patient rights.”

Ziegler counters that patients have the right to try and save their own lives, saying if the Texas bills pass: “chronically ill, no option patients in the US, will have the opportunity to seek treatment without having to leave the country.”

It’s a debate we are all too familiar with at CIRM. Every day we get emails and phone calls from people asking for help in finding a treatment, for them or a loved one, suffering from a life-threatening or life-altering disease or disorder. It’s incredibly difficult having to tell them there is nothing that would help them currently being tested in a clinical trial.

Inevitably they ask about treatments they have seen online, offered by clinics using the patient’s own stem cells to treat them. At that point, it is no longer an academic debate about proven or unproven therapies, it has become personal; one person asking another for help, to find something, anything, to save their life.

Barring a dramatic change of policy at the FDA. these clinics are not going to go away. Nor will the need of patients who have run out of options and are willing to try anything to ease their pain or delay death. We need to find another way, one that brings these clinics into the fold and makes the treatments they offer part of the clinical trial process.

There are no easy answers, no simple solutions. But standing on either side of the divide, saying those on the other side are either “heartless” or “foolish” serves no one, helps no one. We need to figure out another way.

Stem cell stories that caught our eye: lab-grown blood stem cells and puffer fish have the same teeth stem cells as humans

/ Karen Ring / Leave a 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.

Scientists finally grow blood stem cells in the lab!

Two exciting stem cell studies broke through the politics-dominated headlines this week. Both studies, published in the journal Nature, demonstrated that human hematopoietic or blood stem cells can be grown in the lab.

This news is a big deal because scientists have yet to make bonafide blood stem cells from pluripotent stem cells or other human cells. These stem cells not only create all the cells in our blood and immune systems, but also can be used to develop therapies for patients with blood cancers and genetic blood disorders.

But to do these experiments, you need a substantial source of blood stem cells – something that has eluded scientists for decades. That’s where these two studies come to the rescue. One study was spearheaded by George Daley at the Boston Children’s Hospital in Massachusetts and the other was led by Shahin Rafii at the Weill Cornell Medical College in New York City.

Researchers have made blood stem cells and progenitor cells from pluripotent stem cells. Credit: Steve Gschmeissner Getty Images

George Daley and his team developed a strategy that matured human induced pluripotent stem cells (iPS cells) into blood-forming stem and progenitor cells. It’s a two-step process that first uses a cocktail of chemicals to make hemogenic endothelium, the embryonic tissue that generates blood stem cells. The second step involved treating these intermediate cells with a combination of seven transcription factors that directed them towards a blood stem cell fate.

These modified human blood stem cells were then transplanted into mice where they developed into blood stem cells that produced blood and immune cells. First author on the study, Ryohichi Sugimura, explained the applications that their technology could be used for in a Boston Children’s Hospital news release,

“This step opens up an opportunity to take cells from patients with genetic blood disorders, use gene editing to correct their genetic defect and make functional blood cells. This also gives us the potential to have a limitless supply of blood stem cells and blood by taking cells from universal donors. This could potentially augment the blood supply for patients who need transfusions.”

The second study by Shahin Rafii and his team at Cornell used a different strategy to generate blood-forming stem cells. Instead of genetically manipulating iPS cells, they selected a more mature cell type to directly reprogram into blood stem cells. Using four transcription factors, they successfully reprogrammed mouse endothelial cells, which line the insides of blood vessels, into blood-forming stem cells that repopulated the blood and immune systems of irradiated mice.

Raffii believe his method is simpler and more efficient than Daley’s. In coverage by Nature News, he commented,

“Using the most efficient method to generate stem cells matters because every time a gene is added to a batch of cells, a large portion of the batch fails to incorporate it and must be thrown out. There is also a risk that some cells will mutate after they are modified in the lab, and could form tumors if they are implanted into people.”

To play devil’s advocate, Daley’s technique might appeal more to some because the starting source of iPS cells is much easier to obtain and culture in the lab than endothelial cells that have to be extracted from the blood vessels of animals or people. Furthermore, Daley argued that his team’s method could “be made more efficient, and [is] less likely to spur tumor growth and other abnormalities in modified cells.”

The Nature News article compares the achievements of both studies and concluded,

“Time will determine which approach succeeds. But the latest advances have buoyed the spirits of researchers who have been frustrated by their inability to generate blood stem cells from iPS cells.”

 

Humans and puffer fish have the same tooth-making stem cells.

Here’s a fun fact for your next blind date: humans and puffer fish share the same genes that are responsible for making teeth. Scientists from the University of Sheffield in England discovered that the stem cells that make teeth in puffer fish are the same stem cells that make the pearly whites in humans. Their work was published in the journal PNAS earlier this week.

Puffer fish. Photo by pingpogz on Flickr.

But if you look at this puffer fish, you’ll see a dramatic difference between its smile and ours – their teeth look more like a beak. Research has shown that the tooth-forming stem cells in puffer fish produce tooth plates that form a beak-like structure, which helps them crush and consume their prey.

So why is this shared evolution between humans and puffer fish important when our teeth look and function so differently? The scientists behind this research believe that studying the pufferfish could unearth answers about tooth loss in humans. The lead author on the study, Dr. Gareth Fraser, concluded in coverage by Phys.org,

“Our study questioned how pufferfish make a beak and now we’ve discovered the stem cells responsible and the genes that govern this process of continuous regeneration. These are also involved in general vertebrate tooth regeneration, including in humans. The fact that all vertebrates regenerate their teeth in the same way with a set of conserved stem cells means that we can use these studies in more obscure fishes to provide clues to how we can address questions of tooth loss in humans.”

Stem cell-derived blood-brain barrier gives more complete picture of Huntington’s disease

/ Todd Dubnicoff / Leave a comment

Like a sophisticated security fence, our bodies have evolved a barrier that protects the brain from potentially harmful substances in the blood but still allows the entry of essential molecules like blood sugar and oxygen. Just like in other parts of the body, the blood vessels and capillaries in the brain are lined with endothelial cells. But in the brain, these cells form extremely tight connections with each other making it nearly impossible for most things to passively squeeze through the blood vessel wall and into the brain fluid.

BloodBrainBarrier

Compared to blood vessels in other parts of the body, brain blood vessels form a much tighter seal to protect the brain.
Image source: Dana and Chris Reeve Foundation

Recent studies have shown defects in the brain-blood barrier are associated with neurodegenerative disorders like Huntington’s disease and as a result becomes leakier. Although the debilitating symptoms of Huntington’s disease – which include involuntary movements, severe mood swings and difficulty swallowing – are primarily due to the gradual death of specific nerve cells, this breakdown in the blood-brain barrier most likely contributes to the deterioration of the Huntington’s brain.

What hasn’t been clear is if mutations in Huntingtin, the gene that is linked to Huntington’s disease, directly impact the specialized endothelial cells within the blood-brain barrier or if these specialized cells are just innocent bystanders of the destruction that occurs as Huntington’s progresses. It’s an important question to answer. If the mutations in Huntingtin directly affect the blood-brain barrier then it could provide a bigger picture of how this incurable, fatal disease works. More importantly, it may provide new avenues for therapy development.

A UC Irvine research team got to the bottom of this question with the help of induced pluripotent stem cells (iPSCs) derived from the skin cells of individuals with Huntington’s disease. Their CIRM-funded study was published this week in Cell Reports.

In a first for a neurodegenerative disease, the researchers coaxed the Huntington’s disease iPSCs in a lab dish to become brain microvascular endothelial cells (BMECs), the specialized cells responsible for forming the blood-brain barrier. The researchers found that the Huntington’s BMECs themselves were indeed dysfunctional. Compared to BMECs derived from unaffected individuals, the Huntington’s BMECs weren’t as good at making new blood vessels, and the vessels they did make were leakier. So the Huntingtin mutation in these BMECs appears to be directly responsible for the faulty blood-brain barrier.

The team dug deeper into this new insight by looking for possible differences in gene activity between the healthy and Huntington’s BMECs. They found that the Wnt group of genes, which plays an important role in the development of the blood-brain barrier, are over active in the Huntington’s BMECs. This altered Wnt activity can explain the leaky defects. In fact, the use of a drug inhibitor of Wnt fixed the defects. Dr. Leslie Thompson, the team lead, described the significance of this finding in a press release:

“Now we know there are internal problems with blood vessels in the brain. This discovery can be used for possible future treatments to seal the leaky blood vessels themselves and to evaluate drug delivery to patients with HD.”

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Study leader, Leslie Thompson. Steve Zylius / UCI

A companion Cell Stem Cell report, also published this week, used the same iPSC-derived blood-brain barrier system. In that study, researchers at Cedars-Sinai pinpointed BMEC defects as the underlying cause of Allan-Herndon-Dudley syndrome, another neurologic condition that causes mental deficits and movement problems. Together these results really drive home the importance of studying the blood-brain barrier function in neurodegenerative disease.

Dr. Ryan Lim, the first author on the UC Irvine study, also points to a larger perspective on the implications of this work:

“These studies together demonstrate the incredible power of iPSCs to help us more fully understand human disease and identify the underlying causes of cellular processes that are altered.”

Bridging the Gap: Regenerating Injured Bones with Stem Cells and Gene Therapy

/ Karen Ring / Leave a comment

Scientists from Cedars-Sinai Medical Center have developed a new stem cell-based technology in animals that mends broken bones that can’t regenerate on their own. Their research was published today in the journal Science Translational Medicine and was funded in part by a CIRM Early Translational Award.

Over two million bone grafts are conducted every year to treat bone fractures caused by accidents, trauma, cancer and disease. In cases where the fractures are small, bone can repair itself and heal the injury. In other cases, the fractures are too wide and grafts are required to replace the missing bone.

It sounds simple, but the bone grafting procedure is far from it and can cause serious problems including graft failure and infection. People that opt to use their own bone (usually from their pelvis) to repair a bone injury can experience intense pain, prolonged recovery time and are at risk for nerve injury and bone instability.

The Cedars-Sinai team is attempting to “bridge the gap” for people with severe bone injuries with an alternative technology that could replace the need for bone grafts. Their strategy combines “an engineering approach with a biological approach to advance regenerative engineering” explained co-senior author Dr. Dan Gazit in a news release.

Gazit’s team developed a biological scaffold composed of a protein called collagen, which is a major component of bone. They implanted these scaffolds into pigs with fractured leg bones by inserting the collagen into the gap created by the bone fracture. Over a two-week period, mesenchymal stem cells from the animal were recruited into the collagen scaffolds.

To ensure that these stem cells generated new bone, the team used a combination of ultrasound and gene therapy to stimulate the stem cells in the collagen scaffolds to repair the bone fractures. Ultrasound pulses, or high frequency sound waves undetectable by the human ear, temporarily created small holes in the cell membranes allowing the delivery of the gene therapy-containing microbubbles into the stem cells.

Image courtesy of Gazit Group/Cedars-Sinai.

Animals that received the collagen transplant and ultrasound gene therapy repaired their fractured leg bones within two months. The strength of the newly regenerated bone was comparable to successfully transplanted bone grafts.

Dr. Gadi Pelled, the other senior author on this study, explained the significance of their research findings for treating bone injuries in humans,

“This study is the first to demonstrate that ultrasound-mediated gene delivery to an animal’s own stem cells can effectively be used to treat non-healing bone fractures. It addresses a major orthopedic unmet need and offers new possibilities for clinical translation.”

You can learn more about this study by watching this research video provided by the Gazit Group at Cedars-Sinai.

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